Final Report Summary - SMARTERSHIELD (Smart erosion shield for electro-mechanical de-icers)
Executive Summary:
Ice accumulation on aircrafts' wings generates severe problems in the vehicle performance mainly due to the combination of weight increase and lift reduction which in turn implies an increase on the energy consumption. This problem is faced nowadays by methods that vary from energetically evaporative anti-ice systems (prevention) to de-icing systems (corrective). The use of evaporative anti-ice systems is hampered nowadays due to the design of new fuel-efficient engines that limit the available amount of bleed air. As a result, more electric aircrafts using large generators to replace bleed air as an energy source have been developed. However, the amount of power that permits a full evaporative anti-icing electrically powered system is still out-of-availability of the current generators. In addition, in the green electric rotorcrafts no bleed air will be available, and therefore electric systems will have to be used. Therefore, spending research efforts in electrically efficient de-icing systems seems to be a good alternative. As regards the known de-icing systems, they are mainly divided into electro-thermal (thermal-based de-icers) and electro-mechanical (deformations-based de-icers) systems While the electro-thermal systems present several disadvantages in terms power needs and secondary effects in the de-icing process among others, the electro-mechanical systems are very well valued for their low power needs (in fact that they are "single points" actuators) and more important, they are non-intrusive to flow. In order to develop more efficient electro-mechanical de-icing systems, innovative technologies and concepts have to be investigated.
The SMARTERSHIELD project has contributed to this investigation by implementing a highly efficient new smart erosion shield. In order to do so, the following main objectives have been undertaken:
1.To investigate propose and review technical concepts and technologies and determine the best design concepts.
2.To find the key parameters and elementary design structure patterns.
3.To maximize the deformations with minimum energy and provide a high control capacity of the deformations.
4.To determine the best design concept.
5.To evolve the best design concept to achieve a highly optimized detail design of a erosion shield prototype.
6.Validate the proposed new design concepts and the prototypes design by means of FEA simulations and the necessary correlation process.
7.To manufacture and assembly erosion shield mock-ups.
8.To manufacture and assembly the testing bench for the mock-ups.
9.To test and validate the mock-ups.
10.To manufacture and assembly the erosion shield prototype.
11.To manufacture and assembly the testing bench for the prototype.
12.To test and validate the erosion shield prototype.
As a summary, the de-icing SMARTSHIELD system has been designed by means of engineering tools such as FEA and prototype design and validated by full-scale experimental tests. In order to maximize the deformations and its control and at the same time minimize the energy spent in the de-icing process, an investigation on the actuator technologies and materials design has been proposed as well.
Project Context and Objectives:
The SMARTERSHIELD project has contributed to this investigation by implementing a highly efficient new smart erosion shield. In order to do so, the following main objectives have been undertaken:
1.To investigate propose and review technical concepts and technologies and determine the best design concepts.
2.To find the key parameters and elementary design structure patterns.
3.To maximize the deformations with minimum energy and provide a high control capacity of the deformations.
4.To determine the best design concept.
5.To evolve the best design concept to achieve a highly optimized detail design of a erosion shield prototype.
6.Validate the proposed new design concepts and the prototypes design by means of FEA simulations and the necessary correlation process.
7.To manufacture and assembly erosion shield mock-ups.
8.To manufacture and assembly the testing bench for the mock-ups.
9.To test and validate the mock-ups.
10.To manufacture and assembly the erosion shield prototype.
11.To manufacture and assembly the testing bench for the prototype.
12.To test and validate the erosion shield prototype.
As a summary, the de-icing SMARTSHIELD system has been designed by means of engineering tools such as FEA and prototype design and validated by full-scale experimental tests. In order to maximize the deformations and its control and at the same time minimize the energy spent in the de-icing process, an investigation on the actuator technologies and materials design has been proposed as well.
Project Results:
The work performed to date since the beginning of the project has been summarized in the documents D1 "New concepts review", D2 "Design and evaluation of new concepts", D3 “Detail design and optimization” and D4 “Erosion shield prototype” that have been delivered.
Regarding the first deliverable, its main objective was to describe the evaluation of the proposed concepts as well as providing a selection that had to be analysed. Firstly, the detailed specifications were established. Parameters such as dimensions, applied boundaries, safety and environmental design criteria and manufacturing possibilities, were considered for the design and development of the erosion shield. Secondly, and in-depth state of the art was performed regarding the de-icing mechanisms. After recollecting all the previous information, the key concepts that would lead to an optimal erosion shield design were listed. Then, the indicators that would give an overall idea about the performance of the erosion shield were determined. After the inputs of the analysis were set, a list of concepts was evaluated through numerical analysis. The results indicated that three concepts were suitable for obtaining good performance of the erosion shield to be designed: anisotropic behaviour, vibration modes and buckling. For all the concepts, the varying parameters that would lead to an optimized erosion shield were, in general, geometrical (thickness, stiffeners) location of the actuators and fixation points, actuation sequence and manufacturing materials. Regarding the most relevant optimization field, it was concluded that the actuation sequence was the most influent parameter.
In relation to the second deliverable, its main objective is to evaluate and optimize the 3 best concepts by FEA, the selection of the best design solution, the development and implementation of the testing bench for mock-ups tests, the results of the experimental tests and the Finite Element model correlation. All these tasks have been carried out, and in addition to the evaluation of the concepts under efficiency (detached area/energy) and weight points of view, safety/controllability, complexity and material costs have been taken into account at the time of defining the best concept for the erosion shield design. According to the evaluation of all results the best concept has been found to be the anisotropic behaviour. Regarding the materials selection, for the already selected concept, it has been seen that the two best options are the aluminium plate with triangular stiffeners and the CFRP plate. In relation to the mock-ups testing and numerical simulation, the tests were successfully carried out. Nonetheless, the correlation of the experimental data and the numerical results did not give the expected level of accuracy. According to the boundaries of the problem and the manufactured samples, the problem must be attributed either to an erroneous manufacturing of the coupons or to a bad estimation of the properties of the CFRP used in the simulations.
Referring to the third deliverable, its main objective is to determine an optimized final design of an erosion shield in comparison to a non optimized design with quasi-static deformation ice detachment capability. In order to fulfil this global objective, some partial goals have been undertaken: Discriminate the most suitable stringers-panel configuration, evaluate the performance of the chosen configurations when actuated either by two or by four application points, determine the best value of all input parameters for an optimal behaviour in terms of overall performance, especially when detaching ice and energy cost, evaluate the validity of the numerical models and asses the structural integrity of the final design. The optimization carried out was performed in terms of detached area, applied energy, mass and maximum VM stress. Next, two candidate points have been selected as optimum cases. These cases have been tested to structural integrity verification. Lastly, one of the optimal cases has been rejected and a panel with curved stringers and two actuators has been selected as a final optimal case.
Regarding to the last deliverable, its main objective is to design a test to check the panel proposed in the previous deliverable. In order to fulfil this global objective, some partial goals have been undertaken: To design a test bench to achieve the boundary conditions (BC) simulated, to test the erosion shield proposed in the previous deliverable and to validate the followed methodology and the results obtained by the virtual tests. A non direct correlation with the erosion shield prototype and the virtual test computed has been observed. However, the work methodology is robust and can be used in the futures projects. The possible interpretations for the non direct correlation real-virtual test are: The creation of the regular ice layer is difficult and this affects to the stiffness of the ice and the interaction of the surface-ice is not well defined.
Progress Summary by Workpackages- Main tasks and S & T results/foregrounds
WP1-EROSION SHIELD DESIGN
Task 1.1. Establishment of detailed specifications:
LEITAT and TRC together with the SGO member have established the detailed mechanical, functional, aeronautical and environmental criteria and specifications as well as wing integration requirements that the erosion shield system have to fulfil. The complete expertise of LEITAT in automation and materials and structures mechanics (including composite materials and Finite Element Analysis) and of TRC in design and manufacturing of aero-structures (including aircraft wings) has been a key factor to successfully accomplish this task. The SGO member has provided the following inputs:
• Erosion shield sizing for final prototype such as surface (length, width...).
• Imposed erosion shield fixations such as boundary edges freedom or fixity and minimum distance between fixation points (the fixation points location remains an open parameter).
• Required materials for lightning strike protection.
• Environmental conditions specification such as temperature range, vibration levels, lightning strike, bird strike, altitude (pressure range).
• Allowable deformation (maximum displacement normal to erosion shield surface).
• Optimization criteria.
This task was completed and reported in D1.1 deliverable (pp. 4-6) on 31-07-2014. The mentioned specifications were particularly related to mechanical, dimensional, safety, environmental and assembly issues.
Task 1.2. New concepts review:
In a first design stage, from the specifications established in Task 1.1 - Establishment of detailed specifications-, and taking advantage of the deep knowledge of LEITAT in automation and materials and structures mechanics, LEITAT has proposed, designed and investigated new concepts of erosion shield systems, including the study of materials, structures, mechanical behaviour (under static and dynamic loads), actuation sequences and mechanical phenomenology (e.g. buckling or twisting), with the main objective of to maximize the deformations, by minimizing the efforts generated by the actuators and by providing at the same time a high control capacity of the deformations. To carry out the designs of the new concepts, LEITAT has made use of CAD-3D design tools. LEITAT and TRC have made use of his deep knowledge in mechanical and aeronautical engineering to carry out a first evaluation of the proposed technologies and concepts to select the most suitable ones for the erosion shield, which has been analyzed in more detail in subsequent design stages.
This task was completed and reported in D1.1 document (pp. 15-26) on 31-07-2014. A brain storming for concepts proposal and investigation of suitability was properly done. The initial concepts were anisotropic behaviour, vibration modes, buckling, scale, meso-structures and lever effect.
Task 1.3. Design and evaluation of new concepts:
In a second design stage, LEITAT has analysed and optimized the previously selected technologies and concepts in Task 1.2 - New concepts review -. LEITAT has simulated and analyse each proposed concept to predict and evaluate its mechanical efficiency and performance (including qualitative analysis of the de-icing capacity and efficiency between designs) by the level 1 simulations carried out in Task 2.2 - Level 1 simulations -. In this way, the best design concepts has been determined (2 or 3 design solutions), which has been manufactured as a mock-ups in Task 3.1 - Manufacturing and assembly of erosion shield mock-ups -. From the experimental tests of mock-ups carried out in the concept validation in Task 3.2 - Concept validation -, LEITAT has determined the best design concept.
This task was completed and reported in D1.1 document (pp. 46-48) on 31-07-2014. All concepts were properly analysed and evaluated. Effectively, the choice of the three best concepts was properly done, and the choice of the best design concept has been presented in the deliverable D1.2 on 31-05-2014.
Task 1.4. Design optimization:
LEITAT has accurately optimized the concept designs in the detail design in Task 1.4 - Detail design -, including materials, material configuration in the case of composite materials, geometries, thicknesses, stiffeners, fixation zones, actuation points, actuation sequences etc., making use of the Design of Experiments technique (DOE), parametric Finite Element models and optimization algorithms such as genetic algorithms, as well as of the level 1 and 2 simulations carried out in Task 2.2 - Level 1 simulations - and Task 2.3 - Level 2 simulations - respectively, evolving the best concept design to a detail design with the main objective of to maximize the deformations by minimizing the efforts generated by the actuators and by providing at the same time a high control capacity of the deformations, as well as to minimize the system weight. In this way, LEITAT has found the key parameters and elementary design structure patterns able to maximize the expected deformations. LEITAT has determined the optimization key parameters and has evaluated their impact on erosion shield performance.
In this task, LEITAT has made use of his deep knowledge on automation and on materials and structures mechanics to assess the mechanical, functional and environmental specifications as well as wing integration requirements considering static and fatigue cases.
This part is the next step after D1.2 is delivered. The best concept design has been defined and the design optimization approach has been done. Delivered in D1.3 document on 15-06-2015.
Task 1.5. Detail design:
In a third design stage, LEITAT has evolved the best concept design determined in Task 1.3 - Design and evaluation of new concepts - to a prototype scale detail design by using CAD-3D tools, determining the more suitable materials, material configuration in the case of composite materials, geometries, thicknesses, stiffeners, fixation zones, actuation points, actuation sequences etc. to ensure the functionality, manufacturability and assembly of the new erosion shield system, and carrying out all the necessary 3D and 2D documentation to manufacture and assembly the prototype in Task 3.4 - Manufacturing and assembly of erosion shield prototype -. LEITAT has accurately optimized the detail design (Task 1.4 - Design optimization -) with the main objective of to maximize the deformations by minimizing the efforts generated by the actuators and by providing at the same time a high control capacity of the deformations, as well as to minimize the system weight.
TRC has made use of his high knowledge in aeronautics and in manufacturing and assembly of aero structures to ensure that the detail design was manufacturable and assemblable and that it fulfilled the aeronautical specifications, by considering the appropriate manufacturing, assembly and aeronautical criteria.
Regarding this task, the initial approach has been done. The detail design is the next step after D1.2 is delivered. Delivered in D1.3 document on 15-06-2015.
Significant Results:
1-Definition of the most suitable optimization parameters.
2-Election of the three best concepts based on complex numerical models.
3-Election of the best design concept in terms of efficiency weight and complexity, controllability and costs.
4-Definition of the materials to be used.
5-Good initial results of the mock-ups testing and validation even though the CFRP mock-ups showed bad correlation to the numerical results. Proposals for improving this correlation have been done.
6-Approach for detail design well defined based on prior results.
WP2-STRUCTURAL SIMULATION AND MODEL CORRELATION
Progress Summary
Task 2.1. Modelling of erosion shield designs:
LEITAT has carried out Finite Element (FE) models for the design concepts and of the prototype scale design as well. LEITAT has generated and configure parametric models including geometry, mesh, materials, contacts, joints, boundary conditions, loads, solver etc. LEITAT has made use of his complete expertise in structural simulation of aeronautical and automotive components, including static/dynamic analysis in implicit/explicit code, buckling and post-buckling analysis and considering different types of nonlinearities such as material, contact or geometrical.
Regarding this task, all concepts have been simulated by means of FEA (D1.1 pp. 18-26). The prototypes have been simulated as well (still to be delivered in D1.2 pp. 31-33). Concepts simulated and delivered on 31-07-2013. Mock-ups simulated and to be delivered on 31-05-2014.
Task 2.2. Level 1 simulations:
LEITAT has used failure criteria for laminate materials (such as Ye's failure criterion for interlaminar damage (delamination) or LaRC failure criterion for intralaminar damage) to accurately analyse how the de-icing mechanism is working in each design concept, to numerically predict the de-icing hot-spots and to qualitatively evaluate and compare the efficiency of the designs to shed the accreted ice. To carry out these simulations, LEITAT has made use of the FE models carried out in Task 2.1 - Modelling of erosion shield designs -. The results of these simulations have been used as an input for Task 1.4 - Design optimization - and Task 2.4 - Model correlation
This task has been properly done and it has been presented in D1.2 (pp. 5-28) on 31-05-2014.
Task 2.3. Level 2 simulations:
The first idea was that LEITAT assess fatigue failure making use of the most suitable approaches depending on the materials of each design, such as S-N curves (load versus number of cycles to failure) and mean stress correction criteria (e.g. Goodman or Soderberg) for metallic materials, or direct cyclic approach and interlaminar damage models (e.g. VCCT technique or the damage model) for composite materials.
Finally this task (mainly fatigue assessment) was not considered needed because the material chosen did not need this kind of analysis.
Task 2.4. Model correlation:
From the simulation results in Task 2.2 - Level 1 simulations - and the experimental results in Task 3.2 - Testing and validation of concept designs -, LEITAT has correlated and adjusted the Finite Element model to maximize its accuracy and reliability. In this way, reliable models have been available to design, optimize and validate the prototype scale erosion shield. LEITAT has evaluated and verified the reliability of the Finite Element model by correlating it from the simulation results in Task 2.3 - Level 2 simulations -, and the experimental results in Task 3.4 - Testing and validation of erosion shield prototype -. The main parameters that have correlated have been the strains on the erosion shield and the loads produced by the actuators. LEITAT has made use of his deep knowledge in materials and structures mechanics and structural simulation of aeronautic and automotive components.
As regards to this task, the mock-ups are not fully correlated. Aluminium gave good results while CFRP did not show a good correlation. The erosion shield model is done and presented in D1.3 on 15-06-2015. On the other hand, the next Task 3.4. – Testing and validation of erosion shield prototype – has demonstrated that the interface interaction parameter is not well defined (because it is a very difficult parameter to define). The method is well defined, but the lack of this parameter has generated an accumulative error. It does not ensure that the virtual optimum design is the real optimum.
Significant Results:
1-Positive results in the simulation of the three selected concepts and in the Aluminium mock-ups. Models are ready to evaluate the optimization detail design.
2-Good prediction of the detached area by means of the Ye's failure criterion.
3-Good correlation of the numerical simulation of the Aluminium mock-ups.
WP 3: MANUFACTURING, TESTING AND VALIDATION
Progress Summary
Task 3.1. Manufacturing and assembly of erosion shield mock-ups:
TRC and LEITAT have acquired the necessary raw materials and components to fabricate and assembly the erosion shield mock-ups allowing its functionality, as well as to manufacture and assembly the testing bench including its implementation with sensors, actuators and data acquisition systems.
TRC has manufactured and assembled mock-ups of the best design concepts (2 or 3 design solutions) determined in the second design stage in Task 1.3 - Design and evaluation of new concepts -. TRC disposes of two autoclaves (2,5 m diam. x 5 m long. and 0,8 m diam. and 2,2 m long.), a CNC fabric cutter, a 5 axis CNC router, CAD-3D design software and a metrology area with metrology equipment such as a metrology table, a metrology arm or a laser tracker.
LEITAT has manufactured and assembled the testing bench for the mock-ups, including its implementation with all the required sensors (such as strain gauges, load cells or electrical energy consumption modules), actuators (such as solenoid actuators) and data acquisition systems. LEITAT disposes of a SDM (Selective Deposition Method) Additive Manufacturing machine, as well as an industrial area with a complete set of tools including a CNC machining centre.
Regarding this task, the testing bench has been manufactured as well. This progress has been presented in D1.2 (pp. 30) on 31-05-2014.
Task 3.2. Testing and validation of design concepts:
LEITAT has tested and validated the best design concepts determined in the second design stage in Task 1.3 - Design and evaluation of new concepts -, making use of the mock-ups and testing bench manufactured and assembled in Task 3.1. LEITAT has monitored and analysed all the available information from the sensors to determine the best design solution (Task 1.3) that has been finally developed as a prototype, as well as to correlate the Finite Element model in Task 2.4 - Model correlation.
TRC has made use of his high knowledge in aeronautics and his complete expertise in manufacturing and assembly of aero-structures to analyse in detail the concept mock-ups and to determine the final manufacture, assembly and aeronautical criteria and specifications to take into account in the prototype detail design.
Regarding this task, the mock-ups have been tested and partially successfully validated. In the case of CFRP mock-ups a bad correlation was obtained. To be presented in D1.2 (pp. 31-33) on 31-05-2014.
Task 3.3. Manufacturing and assembly of erosion shield prototype:
TRC and LEITAT have acquired the necessary raw materials and components to fabricate each part and to assembly the erosion shield prototype allowing its functionality, as well as to manufacture and assembly the testing bench including its implementation with sensors, actuators and data acquisition systems.
TRC has manufactured and assembled the erosion shield prototype determined in the second design stage (Task 1.5 - Detail design -), including the lightning strike protection materials. TRC disposes of two autoclaves (2,5 m diam. x 5 m long. and 0,8 m diam. and 2,2 m long.), a CNC fabric cutter, a 5 axis CNC router, CAD-3D design software and a metrology area with metrology equipment such as a metrology table, a metrology arm or a laser tracker.
LEITAT has manufactured and assembled the testing bench for the erosion shield prototype, including its implementation with all the required sensors (such as strain gauges, load cells or electrical energy consumption modules), actuators (such as solenoid actuators) and data acquisition systems. LEITAT disposes of a SDM (Selective Deposition Method) Additive Manufacturing machine, as well as an industrial area with a complete set of tools including a CNC machining centre.
This task has been properly done and it has been presented in D3.4 (pp. 4-6) on 31-07-2015.
Task 3.4. Testing and validation of erosion shield prototype
LEITAT has tested and validated the prototype fabricated in Task 3.3 making use of the testing bench manufactured and assembled in said task. LEITAT has monitored and analysed all the available information from the sensors to accurately study and validate its behaviour and efficiency.
Finally, this task demonstrates that there is no quantitative correlation between the model and the demonstrator prototype. In a possible future projects, the interface interaction parameter should be studied in depth. This task has been properly done and it has been presented in D3.4 (pp. 7-11) on 31-07-2015.
Significant Results:
1- Mock-ups were manufactured on time even though they showed a non expected curvature in the in-plane direction.
2- Experimental and numerical results were achieved. The correlation of the CFRP mock-ups were under the acceptable limits and it should be considered the possibility of repeating this step.
3- The work methodology is robust and can be used in the futures projects
4- The creation of the regular ice layer is difficult and this affects to the stiffness of the ice.
5- The interaction of the surface-ice is not well defined.
Potential Impact:
This project was aimed to design a new smart erosion shield that addresses all the challenges associated with this development and proposes innovative solutions. Various aspects on how to achieve the best erosion shield in terms of efficiency, cost, reliability, design and functionality have been investigated. SMARTERSHIELD solutions include:
i.The utilization of a number of actuators based on piezoelectric, solenoid or wire technology.
ii.Using innovative materials and structural solutions such as mesostructures and biomaterials to induce controlled deformations without actuators.
iii.Numerical calculations and simulations to optimize the design of the new erosion shield.
iv.Icing and de-icing experimental tests.
The development of the smart erosion shield solutions in terms of environmental, economical and social impacts have been carried out.
In terms of environment, aviation contributes approximately 2% of the total man made CO2, and the EU has set the target to reduce emissions by 85-90% below 1990 levels by 2050. This includes a reduction of at least 60% of greenhouse gasses (GHG). Even though this project does not directly tackle this issue, it contributes to the reduction of emissions. The aerodynamic design of the aircraft has direct contribution to fuel efficiency and consequently the amount of emission. The new erosion shield developed within the SMARTERSHIELD project has contributed to the reduction of emissions.
Moreover, SMARTERSHIELD contributes to the European transport policy which is in line with the Euro 2020 initiative in working towards “resource efficient Europe”. This is achieved by facilitating economic progress, enhancing competitiveness and offering high quality mobility while using resources more efficiently. In addition, the project is geared towards developing solutions to reduce cost by using new methods for more efficient systems that require minimal maintenance and replacement. These new methods contribute in a more efficient use of energy.
In terms of socio-economics, SMARTERSHILED has enhanced European competitiveness and facilitate economic progress. The European Air Transport sector has an annual turnover of more than € 95 billion and employs over half a million people directly with another 2.6 million indirect jobs. The participation of local partners such as TR COMPOSITES to this project is profitable to gain high added value from the development of the new erosion shield in terms increased revenue, sales, new market opportunities and job creation. SMARTERSHIELD results have also contributed to enhancing the safety of aircrafts with new safer and more efficient technologies. Other markets that could take profit of the new solutions developed in the SMARTERSHIELD project are the wind turbines (WT) sectors.
WT operating in cold regions or at high altitudes are frequently facing icing conditions during winter operation, and at the same time, the best sites for wind farm installation are located at higher altitudes, as wind speed generally increases by 0.1m/s per 100m of altitude for the first 1000m. Therefore, wind farms installed in some of the best wind sites around the world are facing possible icing events. SMARTERSHIELD project has been useful to explore how this technology can be used in other systems and sectors as well. The application of the new erosion shield could be transferred for instance to Rotorcraft industry to produce energetic efficient de-icing systems for helicopter blades. In terms of aircraft safety, Europe has a good record, and it aims to be the safest region in aviation.
List of Websites:
http://ipo.leitat.org/smartershield/
Ice accumulation on aircrafts' wings generates severe problems in the vehicle performance mainly due to the combination of weight increase and lift reduction which in turn implies an increase on the energy consumption. This problem is faced nowadays by methods that vary from energetically evaporative anti-ice systems (prevention) to de-icing systems (corrective). The use of evaporative anti-ice systems is hampered nowadays due to the design of new fuel-efficient engines that limit the available amount of bleed air. As a result, more electric aircrafts using large generators to replace bleed air as an energy source have been developed. However, the amount of power that permits a full evaporative anti-icing electrically powered system is still out-of-availability of the current generators. In addition, in the green electric rotorcrafts no bleed air will be available, and therefore electric systems will have to be used. Therefore, spending research efforts in electrically efficient de-icing systems seems to be a good alternative. As regards the known de-icing systems, they are mainly divided into electro-thermal (thermal-based de-icers) and electro-mechanical (deformations-based de-icers) systems While the electro-thermal systems present several disadvantages in terms power needs and secondary effects in the de-icing process among others, the electro-mechanical systems are very well valued for their low power needs (in fact that they are "single points" actuators) and more important, they are non-intrusive to flow. In order to develop more efficient electro-mechanical de-icing systems, innovative technologies and concepts have to be investigated.
The SMARTERSHIELD project has contributed to this investigation by implementing a highly efficient new smart erosion shield. In order to do so, the following main objectives have been undertaken:
1.To investigate propose and review technical concepts and technologies and determine the best design concepts.
2.To find the key parameters and elementary design structure patterns.
3.To maximize the deformations with minimum energy and provide a high control capacity of the deformations.
4.To determine the best design concept.
5.To evolve the best design concept to achieve a highly optimized detail design of a erosion shield prototype.
6.Validate the proposed new design concepts and the prototypes design by means of FEA simulations and the necessary correlation process.
7.To manufacture and assembly erosion shield mock-ups.
8.To manufacture and assembly the testing bench for the mock-ups.
9.To test and validate the mock-ups.
10.To manufacture and assembly the erosion shield prototype.
11.To manufacture and assembly the testing bench for the prototype.
12.To test and validate the erosion shield prototype.
As a summary, the de-icing SMARTSHIELD system has been designed by means of engineering tools such as FEA and prototype design and validated by full-scale experimental tests. In order to maximize the deformations and its control and at the same time minimize the energy spent in the de-icing process, an investigation on the actuator technologies and materials design has been proposed as well.
Project Context and Objectives:
The SMARTERSHIELD project has contributed to this investigation by implementing a highly efficient new smart erosion shield. In order to do so, the following main objectives have been undertaken:
1.To investigate propose and review technical concepts and technologies and determine the best design concepts.
2.To find the key parameters and elementary design structure patterns.
3.To maximize the deformations with minimum energy and provide a high control capacity of the deformations.
4.To determine the best design concept.
5.To evolve the best design concept to achieve a highly optimized detail design of a erosion shield prototype.
6.Validate the proposed new design concepts and the prototypes design by means of FEA simulations and the necessary correlation process.
7.To manufacture and assembly erosion shield mock-ups.
8.To manufacture and assembly the testing bench for the mock-ups.
9.To test and validate the mock-ups.
10.To manufacture and assembly the erosion shield prototype.
11.To manufacture and assembly the testing bench for the prototype.
12.To test and validate the erosion shield prototype.
As a summary, the de-icing SMARTSHIELD system has been designed by means of engineering tools such as FEA and prototype design and validated by full-scale experimental tests. In order to maximize the deformations and its control and at the same time minimize the energy spent in the de-icing process, an investigation on the actuator technologies and materials design has been proposed as well.
Project Results:
The work performed to date since the beginning of the project has been summarized in the documents D1 "New concepts review", D2 "Design and evaluation of new concepts", D3 “Detail design and optimization” and D4 “Erosion shield prototype” that have been delivered.
Regarding the first deliverable, its main objective was to describe the evaluation of the proposed concepts as well as providing a selection that had to be analysed. Firstly, the detailed specifications were established. Parameters such as dimensions, applied boundaries, safety and environmental design criteria and manufacturing possibilities, were considered for the design and development of the erosion shield. Secondly, and in-depth state of the art was performed regarding the de-icing mechanisms. After recollecting all the previous information, the key concepts that would lead to an optimal erosion shield design were listed. Then, the indicators that would give an overall idea about the performance of the erosion shield were determined. After the inputs of the analysis were set, a list of concepts was evaluated through numerical analysis. The results indicated that three concepts were suitable for obtaining good performance of the erosion shield to be designed: anisotropic behaviour, vibration modes and buckling. For all the concepts, the varying parameters that would lead to an optimized erosion shield were, in general, geometrical (thickness, stiffeners) location of the actuators and fixation points, actuation sequence and manufacturing materials. Regarding the most relevant optimization field, it was concluded that the actuation sequence was the most influent parameter.
In relation to the second deliverable, its main objective is to evaluate and optimize the 3 best concepts by FEA, the selection of the best design solution, the development and implementation of the testing bench for mock-ups tests, the results of the experimental tests and the Finite Element model correlation. All these tasks have been carried out, and in addition to the evaluation of the concepts under efficiency (detached area/energy) and weight points of view, safety/controllability, complexity and material costs have been taken into account at the time of defining the best concept for the erosion shield design. According to the evaluation of all results the best concept has been found to be the anisotropic behaviour. Regarding the materials selection, for the already selected concept, it has been seen that the two best options are the aluminium plate with triangular stiffeners and the CFRP plate. In relation to the mock-ups testing and numerical simulation, the tests were successfully carried out. Nonetheless, the correlation of the experimental data and the numerical results did not give the expected level of accuracy. According to the boundaries of the problem and the manufactured samples, the problem must be attributed either to an erroneous manufacturing of the coupons or to a bad estimation of the properties of the CFRP used in the simulations.
Referring to the third deliverable, its main objective is to determine an optimized final design of an erosion shield in comparison to a non optimized design with quasi-static deformation ice detachment capability. In order to fulfil this global objective, some partial goals have been undertaken: Discriminate the most suitable stringers-panel configuration, evaluate the performance of the chosen configurations when actuated either by two or by four application points, determine the best value of all input parameters for an optimal behaviour in terms of overall performance, especially when detaching ice and energy cost, evaluate the validity of the numerical models and asses the structural integrity of the final design. The optimization carried out was performed in terms of detached area, applied energy, mass and maximum VM stress. Next, two candidate points have been selected as optimum cases. These cases have been tested to structural integrity verification. Lastly, one of the optimal cases has been rejected and a panel with curved stringers and two actuators has been selected as a final optimal case.
Regarding to the last deliverable, its main objective is to design a test to check the panel proposed in the previous deliverable. In order to fulfil this global objective, some partial goals have been undertaken: To design a test bench to achieve the boundary conditions (BC) simulated, to test the erosion shield proposed in the previous deliverable and to validate the followed methodology and the results obtained by the virtual tests. A non direct correlation with the erosion shield prototype and the virtual test computed has been observed. However, the work methodology is robust and can be used in the futures projects. The possible interpretations for the non direct correlation real-virtual test are: The creation of the regular ice layer is difficult and this affects to the stiffness of the ice and the interaction of the surface-ice is not well defined.
Progress Summary by Workpackages- Main tasks and S & T results/foregrounds
WP1-EROSION SHIELD DESIGN
Task 1.1. Establishment of detailed specifications:
LEITAT and TRC together with the SGO member have established the detailed mechanical, functional, aeronautical and environmental criteria and specifications as well as wing integration requirements that the erosion shield system have to fulfil. The complete expertise of LEITAT in automation and materials and structures mechanics (including composite materials and Finite Element Analysis) and of TRC in design and manufacturing of aero-structures (including aircraft wings) has been a key factor to successfully accomplish this task. The SGO member has provided the following inputs:
• Erosion shield sizing for final prototype such as surface (length, width...).
• Imposed erosion shield fixations such as boundary edges freedom or fixity and minimum distance between fixation points (the fixation points location remains an open parameter).
• Required materials for lightning strike protection.
• Environmental conditions specification such as temperature range, vibration levels, lightning strike, bird strike, altitude (pressure range).
• Allowable deformation (maximum displacement normal to erosion shield surface).
• Optimization criteria.
This task was completed and reported in D1.1 deliverable (pp. 4-6) on 31-07-2014. The mentioned specifications were particularly related to mechanical, dimensional, safety, environmental and assembly issues.
Task 1.2. New concepts review:
In a first design stage, from the specifications established in Task 1.1 - Establishment of detailed specifications-, and taking advantage of the deep knowledge of LEITAT in automation and materials and structures mechanics, LEITAT has proposed, designed and investigated new concepts of erosion shield systems, including the study of materials, structures, mechanical behaviour (under static and dynamic loads), actuation sequences and mechanical phenomenology (e.g. buckling or twisting), with the main objective of to maximize the deformations, by minimizing the efforts generated by the actuators and by providing at the same time a high control capacity of the deformations. To carry out the designs of the new concepts, LEITAT has made use of CAD-3D design tools. LEITAT and TRC have made use of his deep knowledge in mechanical and aeronautical engineering to carry out a first evaluation of the proposed technologies and concepts to select the most suitable ones for the erosion shield, which has been analyzed in more detail in subsequent design stages.
This task was completed and reported in D1.1 document (pp. 15-26) on 31-07-2014. A brain storming for concepts proposal and investigation of suitability was properly done. The initial concepts were anisotropic behaviour, vibration modes, buckling, scale, meso-structures and lever effect.
Task 1.3. Design and evaluation of new concepts:
In a second design stage, LEITAT has analysed and optimized the previously selected technologies and concepts in Task 1.2 - New concepts review -. LEITAT has simulated and analyse each proposed concept to predict and evaluate its mechanical efficiency and performance (including qualitative analysis of the de-icing capacity and efficiency between designs) by the level 1 simulations carried out in Task 2.2 - Level 1 simulations -. In this way, the best design concepts has been determined (2 or 3 design solutions), which has been manufactured as a mock-ups in Task 3.1 - Manufacturing and assembly of erosion shield mock-ups -. From the experimental tests of mock-ups carried out in the concept validation in Task 3.2 - Concept validation -, LEITAT has determined the best design concept.
This task was completed and reported in D1.1 document (pp. 46-48) on 31-07-2014. All concepts were properly analysed and evaluated. Effectively, the choice of the three best concepts was properly done, and the choice of the best design concept has been presented in the deliverable D1.2 on 31-05-2014.
Task 1.4. Design optimization:
LEITAT has accurately optimized the concept designs in the detail design in Task 1.4 - Detail design -, including materials, material configuration in the case of composite materials, geometries, thicknesses, stiffeners, fixation zones, actuation points, actuation sequences etc., making use of the Design of Experiments technique (DOE), parametric Finite Element models and optimization algorithms such as genetic algorithms, as well as of the level 1 and 2 simulations carried out in Task 2.2 - Level 1 simulations - and Task 2.3 - Level 2 simulations - respectively, evolving the best concept design to a detail design with the main objective of to maximize the deformations by minimizing the efforts generated by the actuators and by providing at the same time a high control capacity of the deformations, as well as to minimize the system weight. In this way, LEITAT has found the key parameters and elementary design structure patterns able to maximize the expected deformations. LEITAT has determined the optimization key parameters and has evaluated their impact on erosion shield performance.
In this task, LEITAT has made use of his deep knowledge on automation and on materials and structures mechanics to assess the mechanical, functional and environmental specifications as well as wing integration requirements considering static and fatigue cases.
This part is the next step after D1.2 is delivered. The best concept design has been defined and the design optimization approach has been done. Delivered in D1.3 document on 15-06-2015.
Task 1.5. Detail design:
In a third design stage, LEITAT has evolved the best concept design determined in Task 1.3 - Design and evaluation of new concepts - to a prototype scale detail design by using CAD-3D tools, determining the more suitable materials, material configuration in the case of composite materials, geometries, thicknesses, stiffeners, fixation zones, actuation points, actuation sequences etc. to ensure the functionality, manufacturability and assembly of the new erosion shield system, and carrying out all the necessary 3D and 2D documentation to manufacture and assembly the prototype in Task 3.4 - Manufacturing and assembly of erosion shield prototype -. LEITAT has accurately optimized the detail design (Task 1.4 - Design optimization -) with the main objective of to maximize the deformations by minimizing the efforts generated by the actuators and by providing at the same time a high control capacity of the deformations, as well as to minimize the system weight.
TRC has made use of his high knowledge in aeronautics and in manufacturing and assembly of aero structures to ensure that the detail design was manufacturable and assemblable and that it fulfilled the aeronautical specifications, by considering the appropriate manufacturing, assembly and aeronautical criteria.
Regarding this task, the initial approach has been done. The detail design is the next step after D1.2 is delivered. Delivered in D1.3 document on 15-06-2015.
Significant Results:
1-Definition of the most suitable optimization parameters.
2-Election of the three best concepts based on complex numerical models.
3-Election of the best design concept in terms of efficiency weight and complexity, controllability and costs.
4-Definition of the materials to be used.
5-Good initial results of the mock-ups testing and validation even though the CFRP mock-ups showed bad correlation to the numerical results. Proposals for improving this correlation have been done.
6-Approach for detail design well defined based on prior results.
WP2-STRUCTURAL SIMULATION AND MODEL CORRELATION
Progress Summary
Task 2.1. Modelling of erosion shield designs:
LEITAT has carried out Finite Element (FE) models for the design concepts and of the prototype scale design as well. LEITAT has generated and configure parametric models including geometry, mesh, materials, contacts, joints, boundary conditions, loads, solver etc. LEITAT has made use of his complete expertise in structural simulation of aeronautical and automotive components, including static/dynamic analysis in implicit/explicit code, buckling and post-buckling analysis and considering different types of nonlinearities such as material, contact or geometrical.
Regarding this task, all concepts have been simulated by means of FEA (D1.1 pp. 18-26). The prototypes have been simulated as well (still to be delivered in D1.2 pp. 31-33). Concepts simulated and delivered on 31-07-2013. Mock-ups simulated and to be delivered on 31-05-2014.
Task 2.2. Level 1 simulations:
LEITAT has used failure criteria for laminate materials (such as Ye's failure criterion for interlaminar damage (delamination) or LaRC failure criterion for intralaminar damage) to accurately analyse how the de-icing mechanism is working in each design concept, to numerically predict the de-icing hot-spots and to qualitatively evaluate and compare the efficiency of the designs to shed the accreted ice. To carry out these simulations, LEITAT has made use of the FE models carried out in Task 2.1 - Modelling of erosion shield designs -. The results of these simulations have been used as an input for Task 1.4 - Design optimization - and Task 2.4 - Model correlation
This task has been properly done and it has been presented in D1.2 (pp. 5-28) on 31-05-2014.
Task 2.3. Level 2 simulations:
The first idea was that LEITAT assess fatigue failure making use of the most suitable approaches depending on the materials of each design, such as S-N curves (load versus number of cycles to failure) and mean stress correction criteria (e.g. Goodman or Soderberg) for metallic materials, or direct cyclic approach and interlaminar damage models (e.g. VCCT technique or the damage model) for composite materials.
Finally this task (mainly fatigue assessment) was not considered needed because the material chosen did not need this kind of analysis.
Task 2.4. Model correlation:
From the simulation results in Task 2.2 - Level 1 simulations - and the experimental results in Task 3.2 - Testing and validation of concept designs -, LEITAT has correlated and adjusted the Finite Element model to maximize its accuracy and reliability. In this way, reliable models have been available to design, optimize and validate the prototype scale erosion shield. LEITAT has evaluated and verified the reliability of the Finite Element model by correlating it from the simulation results in Task 2.3 - Level 2 simulations -, and the experimental results in Task 3.4 - Testing and validation of erosion shield prototype -. The main parameters that have correlated have been the strains on the erosion shield and the loads produced by the actuators. LEITAT has made use of his deep knowledge in materials and structures mechanics and structural simulation of aeronautic and automotive components.
As regards to this task, the mock-ups are not fully correlated. Aluminium gave good results while CFRP did not show a good correlation. The erosion shield model is done and presented in D1.3 on 15-06-2015. On the other hand, the next Task 3.4. – Testing and validation of erosion shield prototype – has demonstrated that the interface interaction parameter is not well defined (because it is a very difficult parameter to define). The method is well defined, but the lack of this parameter has generated an accumulative error. It does not ensure that the virtual optimum design is the real optimum.
Significant Results:
1-Positive results in the simulation of the three selected concepts and in the Aluminium mock-ups. Models are ready to evaluate the optimization detail design.
2-Good prediction of the detached area by means of the Ye's failure criterion.
3-Good correlation of the numerical simulation of the Aluminium mock-ups.
WP 3: MANUFACTURING, TESTING AND VALIDATION
Progress Summary
Task 3.1. Manufacturing and assembly of erosion shield mock-ups:
TRC and LEITAT have acquired the necessary raw materials and components to fabricate and assembly the erosion shield mock-ups allowing its functionality, as well as to manufacture and assembly the testing bench including its implementation with sensors, actuators and data acquisition systems.
TRC has manufactured and assembled mock-ups of the best design concepts (2 or 3 design solutions) determined in the second design stage in Task 1.3 - Design and evaluation of new concepts -. TRC disposes of two autoclaves (2,5 m diam. x 5 m long. and 0,8 m diam. and 2,2 m long.), a CNC fabric cutter, a 5 axis CNC router, CAD-3D design software and a metrology area with metrology equipment such as a metrology table, a metrology arm or a laser tracker.
LEITAT has manufactured and assembled the testing bench for the mock-ups, including its implementation with all the required sensors (such as strain gauges, load cells or electrical energy consumption modules), actuators (such as solenoid actuators) and data acquisition systems. LEITAT disposes of a SDM (Selective Deposition Method) Additive Manufacturing machine, as well as an industrial area with a complete set of tools including a CNC machining centre.
Regarding this task, the testing bench has been manufactured as well. This progress has been presented in D1.2 (pp. 30) on 31-05-2014.
Task 3.2. Testing and validation of design concepts:
LEITAT has tested and validated the best design concepts determined in the second design stage in Task 1.3 - Design and evaluation of new concepts -, making use of the mock-ups and testing bench manufactured and assembled in Task 3.1. LEITAT has monitored and analysed all the available information from the sensors to determine the best design solution (Task 1.3) that has been finally developed as a prototype, as well as to correlate the Finite Element model in Task 2.4 - Model correlation.
TRC has made use of his high knowledge in aeronautics and his complete expertise in manufacturing and assembly of aero-structures to analyse in detail the concept mock-ups and to determine the final manufacture, assembly and aeronautical criteria and specifications to take into account in the prototype detail design.
Regarding this task, the mock-ups have been tested and partially successfully validated. In the case of CFRP mock-ups a bad correlation was obtained. To be presented in D1.2 (pp. 31-33) on 31-05-2014.
Task 3.3. Manufacturing and assembly of erosion shield prototype:
TRC and LEITAT have acquired the necessary raw materials and components to fabricate each part and to assembly the erosion shield prototype allowing its functionality, as well as to manufacture and assembly the testing bench including its implementation with sensors, actuators and data acquisition systems.
TRC has manufactured and assembled the erosion shield prototype determined in the second design stage (Task 1.5 - Detail design -), including the lightning strike protection materials. TRC disposes of two autoclaves (2,5 m diam. x 5 m long. and 0,8 m diam. and 2,2 m long.), a CNC fabric cutter, a 5 axis CNC router, CAD-3D design software and a metrology area with metrology equipment such as a metrology table, a metrology arm or a laser tracker.
LEITAT has manufactured and assembled the testing bench for the erosion shield prototype, including its implementation with all the required sensors (such as strain gauges, load cells or electrical energy consumption modules), actuators (such as solenoid actuators) and data acquisition systems. LEITAT disposes of a SDM (Selective Deposition Method) Additive Manufacturing machine, as well as an industrial area with a complete set of tools including a CNC machining centre.
This task has been properly done and it has been presented in D3.4 (pp. 4-6) on 31-07-2015.
Task 3.4. Testing and validation of erosion shield prototype
LEITAT has tested and validated the prototype fabricated in Task 3.3 making use of the testing bench manufactured and assembled in said task. LEITAT has monitored and analysed all the available information from the sensors to accurately study and validate its behaviour and efficiency.
Finally, this task demonstrates that there is no quantitative correlation between the model and the demonstrator prototype. In a possible future projects, the interface interaction parameter should be studied in depth. This task has been properly done and it has been presented in D3.4 (pp. 7-11) on 31-07-2015.
Significant Results:
1- Mock-ups were manufactured on time even though they showed a non expected curvature in the in-plane direction.
2- Experimental and numerical results were achieved. The correlation of the CFRP mock-ups were under the acceptable limits and it should be considered the possibility of repeating this step.
3- The work methodology is robust and can be used in the futures projects
4- The creation of the regular ice layer is difficult and this affects to the stiffness of the ice.
5- The interaction of the surface-ice is not well defined.
Potential Impact:
This project was aimed to design a new smart erosion shield that addresses all the challenges associated with this development and proposes innovative solutions. Various aspects on how to achieve the best erosion shield in terms of efficiency, cost, reliability, design and functionality have been investigated. SMARTERSHIELD solutions include:
i.The utilization of a number of actuators based on piezoelectric, solenoid or wire technology.
ii.Using innovative materials and structural solutions such as mesostructures and biomaterials to induce controlled deformations without actuators.
iii.Numerical calculations and simulations to optimize the design of the new erosion shield.
iv.Icing and de-icing experimental tests.
The development of the smart erosion shield solutions in terms of environmental, economical and social impacts have been carried out.
In terms of environment, aviation contributes approximately 2% of the total man made CO2, and the EU has set the target to reduce emissions by 85-90% below 1990 levels by 2050. This includes a reduction of at least 60% of greenhouse gasses (GHG). Even though this project does not directly tackle this issue, it contributes to the reduction of emissions. The aerodynamic design of the aircraft has direct contribution to fuel efficiency and consequently the amount of emission. The new erosion shield developed within the SMARTERSHIELD project has contributed to the reduction of emissions.
Moreover, SMARTERSHIELD contributes to the European transport policy which is in line with the Euro 2020 initiative in working towards “resource efficient Europe”. This is achieved by facilitating economic progress, enhancing competitiveness and offering high quality mobility while using resources more efficiently. In addition, the project is geared towards developing solutions to reduce cost by using new methods for more efficient systems that require minimal maintenance and replacement. These new methods contribute in a more efficient use of energy.
In terms of socio-economics, SMARTERSHILED has enhanced European competitiveness and facilitate economic progress. The European Air Transport sector has an annual turnover of more than € 95 billion and employs over half a million people directly with another 2.6 million indirect jobs. The participation of local partners such as TR COMPOSITES to this project is profitable to gain high added value from the development of the new erosion shield in terms increased revenue, sales, new market opportunities and job creation. SMARTERSHIELD results have also contributed to enhancing the safety of aircrafts with new safer and more efficient technologies. Other markets that could take profit of the new solutions developed in the SMARTERSHIELD project are the wind turbines (WT) sectors.
WT operating in cold regions or at high altitudes are frequently facing icing conditions during winter operation, and at the same time, the best sites for wind farm installation are located at higher altitudes, as wind speed generally increases by 0.1m/s per 100m of altitude for the first 1000m. Therefore, wind farms installed in some of the best wind sites around the world are facing possible icing events. SMARTERSHIELD project has been useful to explore how this technology can be used in other systems and sectors as well. The application of the new erosion shield could be transferred for instance to Rotorcraft industry to produce energetic efficient de-icing systems for helicopter blades. In terms of aircraft safety, Europe has a good record, and it aims to be the safest region in aviation.
List of Websites:
http://ipo.leitat.org/smartershield/
