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Advanced Simulation of Aircraft Mechanisms

Final Report Summary - ASAM (Advanced Simulation of Aircraft Mechanisms)

Executive Summary:
The ASAM research project has investigated advanced design and simulation methods for load control and alleviation devices and high lift devices. The research focussed on novel methods for modelling of aerodynamic loads on flexible bodies, modelling of actuators and methods for concept configuration. Also a method for sizing of composite structures has been established. Therefore multi-body simulation tools have been extended and a composite structural sizing method has been developed.
The novel methods have been evaluated by preliminary and detailed conceptual design studies of 3 mechanisms, Krueger Flap, Single Slotted flap and load control and alleviation devices, for a Geared Turbo Fan regional aircraft. The load control and alleviation devices were a split aileron and mini-tabs at trailing edge of the Single Slotted flaps. For each of these mechanisms, a preliminary design study and a detailed design has been performed. The preliminary design study performed the definition of the mechanism and actuation kinematics. The detailed design included the structural sizing of the flaps in unidirectional composite materials and sizing of other metal parts such as hinges, actuator supports and flap tracks. Integration of the mechanisms in the wing structure was also considered.
The design of the Single Slotted flaps of the Turbo-Prop aircraft was not performed due to unavailability of the required input data.

Project Context and Objectives:
The ASAM research project has investigated advanced design and simulation methods for Load control and alleviation devices and high lift devices. The research has focussed on novel methods for modelling of aerodynamic loads on flexible bodies, modelling of actuators and methods for concept configuration. Also a method for sizing of composite structures has been established. The novel methods will be evaluated in context of preliminary and detailed design studies of 4 mechanisms as specified in the call.
Therefore the objective of the project is to perform the detailed conceptual design of the following mechanisms:
1. Krueger Flap (GTF)
2. Single Slotted Flap (GTF)
3. LC&A devices (GTF)
4. Single Slotted Flap (TP)
For each mechanism, the design is divided in 2 phases:
• Preliminary design studies which will be the responsibility of NOVOTECH.
• detailed conceptual designs which will be the responsibility of LMS
For each mechanism, one deliverable is planned for Folwer design and one for the detailed conceptual design. LMS had an additional deliverable regarding the investigation of the improved simulation methods for modelling of aerodynamic loads on flexible bodies, modelling of actuators and methods for concept configuration. Furthermore, a specific deliverable was defined regarding the dissemination and knowledge transfer to the topic manager.
This resulted in the following 10 deliverables:
1. D1.1 Preliminary design studies of Krueger Flap for GTF
2. D1.2 Preliminary design studies of Single Slotted Flap for GTF
3. D1.3 Preliminary design studies of LC&A devices for GTF
4. D1.4 Preliminary design studies of Single Slotted Flap for TP
5. D2.1 Improved simulation methods
6. D2.2 Detailed design studies of Krueger Flap for GTF
7. D2.3 Detailed design studies of Single Slotted Flap for GTF
8. D2.4 Detailed design studies of LC&A devices for GTF
9. D2.5 Detailed design studies of Single Slotted Flap for TP
10. D3.1 Knowledge transfer and dissemination
A milestone will be reached when the preliminary design studies for all mechanisms are completed. A second milestone will be reached when the detailed conceptual designs will be completed for all mechanisms. A final milestone will be reached with all dissemination and knowledge transfer has been completed.

Project Results:
a. Modelling of aerodynamic loads
Current situation to include aero-elastic effects in mechanism simulation in a multi-body simulation:
- Define additional aerodynamic mesh
- Define multi-point constraints (MPCs) between aerodynamic mesh and structural mesh
- Define vector forces for every aerodynamic mesh
- Define look-up tables that are linked with vector force elements
- Consequence: a lot of manual work by the user resulting in a complex simulation model
Aim of this task: Investigate the use of the modal-force approach to define aerodynamic loads on a linear flexible structure
Advantages:
- The user only needs to add 1 element to apply the aerodynamic force.
- The aerodynamic force is descripted in a simple text file.
- The aerodynamic force can be described as either a list of nodal forces or modal Aerodynamic Influence Coefficients that can be obtained directly from an Doublet Lattice analysis (E.g. Nastran SOL 144)
A demonstrator element has been deleveloped and validated that confirms that:
- Only 1 element in GUI to define a distrbuted force
- No need of additonal RBE2/3 in FE model
- Rigid and flexible forces can be applied separately which is useful for aeroelastic simulations
- In order to obtain the correct deformation and reaction loads, a Craig-Bampton mode set should be used. This mode set contains both the normal modes and static constraint modes.

b. Modelling of actuators
Different modelling techniques have been studied for modelling each part of electro-mechanical actuators and electro-hydrostatic actuators. The advantages and disadvantages of different modelling techniques for the following parts:
- Controllers
- Electrical system
o Tabulated model
o Physical models
- Hydraulic system
o Ideal Hydraulic blocks
o Hydraulic Component Design
- Mechanical system
o Input functions
o 2D mechanical library
o 3D dynamic multi-body simulation
The LMS software, LMS Imagine.Lab Amesim, it is suited for modelling of Electro-Mechanical and Electro-Hydrostatic actuators since these systems consist of multiple physical domains and the model fidelity can easily be scaled from system level to component level.
Therefore the recommended modelling approach for the ASAM project is identified as follows:
- Controller: LMS Imagine.Lab AMESim signal and control library covers all requirements.
- Electrical system: Physical Models if relevant parameters are available otherwise Tabulated Models will be sufficient
- Hydraulic system: Ideal Components for system behaviour, perhaps detailed model for the hydraulic jack.
- Mechanical system: loads obtained with LMS Virtual.Lab Motion as input data function.

c. Methods for configuration of concept simulation models
Current modelling approach: one analysis document containing the complete mechanism to be simulated.
Aim of this task: investigate methodologies for configuration management: complex mechanisms are created by combining different subsystems. By splitting the mechanism into several submechanisms, each submechanism can be included or excluded from the simulation, allowing to rapidly test different configurations.
This modelling approach has several advantages:
- Modularity: subsystems that are used multiple times but have to be modelled only once. E.g. an actuator.
- Scalability: models of different fidelity could be used depending on the simulation needs. E.g. Rigid representation can be used during preliminary design, while flexible representation can be used during detailed design
A simple ‘Vertical’, based on the LMS Virtual.Lab Composer framework, has been created for the ASAM project that demonstrates the possibility to use one submechanism at different locations of the mechanism, showing the modularity principle. This research focused on the duplication of a complete submechanism and methodology of deducting the correct connection between the different mechanisms.
The following investigations have been performed:
- Creation of a preliminary model of an actuation system that can be reused in modular and scale manner in a multi-body simulation model of a complete system.
- Methodology to properly handle published axis systems such that the geometry is correctly aligned.
A demonstrator has been created for a ‘Vertical’ for aircraft control surfaces based on the Virtual.Lab Composer to streamline and automate the modelling process for rapidly combining different submechanisms to simulate different configurations

d. Method for sizing of composite structures
Based on literature review and additional research, a structural sizing procedure for unidirectional composite flap as required in the ASAM project has been established. This procedure is summarised as follows:
1. Calculation of equivalent aerodynamic pressure distribution
2. Calculate equivalent quasi-isotropic stiffness using the given ply properties
3. Perform static FEA of all load cases with quasi-isotropic material with equivalent stiffness
4. Calculate the composite ply lay-up
5. Validate static stress analysis, if failed change the ply lay-up
6. Validate buckling behaviour, if failed change the ply lay-up or add stringers
This procedure was used to identify the optimal ply layup for the stars, ribs and skin of the flaps for high lift and LC&A devices.

e. Preliminary design of Krueger Flap for GTF
The report “WP1. Detailed conceptual design – Krueger Flaps (GTF)” (D1.1) describes the process and results of the detailed preliminary design of the Krueger flap for the geared turbo fan (GTF) regional aircraft that is being developed in the Green Regional Aircraft (GRA) project of the JTI Clean Sky European research programme. The design is based on the CAD and the aerodynamic specifications data that has been provided by the Topic Manager. The main objective of the preliminary design was to identify the mechanism and actuation kinematics of the leading edge device and fix the main design parameters.

f. Preliminary design of Single Slotted Flap for GTF
The report “WP1. Detailed conceptual design – Fowler Flaps (GTF)” (D1.2) describes the process and results of the detailed preliminary design of the Fowler flap for the geared turbo fan (GTF) regional aircraft that is being developed in the Green Regional Aircraft (GRA) project of the JTI Clean Sky European research programme. The design is based on the CAD and the aerodynamic specifications data that has been provided by the Topic Manager. The main objective of the preliminary design was to identify the mechanism and actuation kinematics of the trailing edge device and fix the main design parameters.

g. Preliminary design of LC&A devices for GTF
The report “WP1. Detailed conceptual design – LC&A devices Flaps (GTF)” (D1.3) describes the process and results of the detailed preliminary design of the Fowler flap for the geared turbo fan (GTF) regional aircraft that is being developed in the Green Regional Aircraft (GRA) project of the JTI Clean Sky European research programme. The design is based on the CAD and the aerodynamic specifications data that has been provided by the Topic Manager. The main objective of the preliminary design was to identify the mechanism and actuation kinematics of the LC&A devices and fix the main design parameters.

h. Structural sizing of Krueger Flap for GTF
The report “WP2. Detailed conceptual design – Krueger Flaps (GTF)” (D2.2) describes the process and results of the detailed conceptual design of the Krueger flap for the geared turbo fan (GTF) regional aircraft that is being developed in the Green Regional Aircraft (GRA) project of the JTI Clean Sky European research programme. The design is according to the CAD and the aerodynamic specifications data that has been provided by the Topic Manager. Furthermore, the design is based on the preliminary design studies from NOVOTECH that has been reported in the Deliverable D1.1.
The main objective of the detailed conceptual design was to perform the structural sizing of the main load bearing components of the Krueger flap mechanisms. Hence it identified the general geometry of these components and the required structural design. Moreover, it identified the integration of the mechanism in the aircraft wing. The design does not consider detailed manufacturing and installation issues.

i. Structural sizing of Single Slotted Flap for GTF
The report “WP2. Detailed conceptual design – Fowler Flaps (GTF)” (D2.3) describes the process and results of the detailed conceptual design of the Fowler flap for the geared turbo fan (GTF) regional aircraft that is being developed in the Green Regional Aircraft (GRA) project of the JTI Clean Sky European research programme. The design is according to the CAD and the aerodynamic specifications data that has been provided by the Topic Manager. Furthermore, the design is based on the preliminary design studies from NOVOTECH that has been reported in the Deliverable D1.1.
The main objective of the detailed conceptual design was to perform the structural sizing of the main load bearing components of the Fowler flap mechanisms, in particular the flap itself and the tracks. Hence it identified the general geometry of these components and the required structural design. Moreover, it identified the integration of the mechanism in the aircraft wing and the integration of the mini-flaps in the flap. The design did not consider detailed manufacturing issues.

j. Structural sizing of LC&A devices for GTF
The report “WP2. Detailed conceptual design – LC&A devices (GTF)” (D2.4) describes the process and results of the detailed conceptual design of the load control and alleviation (LC&A) devices for the geared turbo fan (GTF) regional aircraft that is being developed in the Green Regional Aircraft (GRA) project of the JTI Clean Sky European research programme. The design is according to the CAD, aerodynamic and actuator specifications data that has been provided by the Topic Manager. Furthermore, the design is based on the preliminary design studies from NOVOTECH that has been reported in the Deliverable D1.3. The main objective of the detailed conceptual design was to perform the structural sizing of the load bearing components of the two split aileron and mini-tab mechanisms. Hence it identified the general geometry of these components and the required structural design. Moreover, it identified the integration of the mechanism in the aircraft wing. The design did not consider manufacturing and installation issues.

Potential Impact:
a. Impact
The first strategic aim of this project was that its outcome is fully aligned with the research objectives that were defined in the related Call for Proposal and as a result, this project will contribute directly to the technology demonstration activities in the Clean Sky Green Regional Aircraft project. This aim has been achieved with the proposed design solutions for the high lift devices and load control and alleviation devices. Consequently, the project will support the evaluation of the feasibility of the technologies that are being developed in the Clean Sky Green Regional Aircraft programme
Additional, the project aimed to address important research topics about the modelling and simulation of the LC&A and high lift devices. The outcome will enable a faster and more accurate simulation of the respective mechanisms and hence will results in shorter development time of aircraft. This will contribute towards the specific objective to “Significantly decreased development cost” defined in the vision for the European aviation sector in 2050 set out by the European Commission. This has also been achieved the improved simulation methods that that have been developed for modelling of aerodynamic loads in mechanism simulation, modelling methods for actuators, methods for configuration management in mechanism models and a methodology for structural sizing of composite flaps.

b. Dissemination activities
Dissemination activities as foreseen in WP3 of the project have been completed. This ensured transfer of all knowledge and information for the consortium partners to the topic manager. These activities included a number of meetings and a software training.
The first public dissemination is planned as a presentation on the results of the ASAM project by Prof. Lecce of Novotech at the Siemens PLM aerospace conference. This is a public conference and presentation will be made available to the public.
Additional conference presentations are anticipated on the results of the ASAM project but are not confirmed yet.

c. Exploitation of the results
As described by the impact of the project, first of all, the Topic Manager will use the results of the project to evaluate some of the technologies that investigated by the Clean Sky Green Regional Aircraft programme. Secondly, the knowledge generated will help the TM and other European manufacturers of high lift and LC&A devices to improve their design process.
Secondly, the improved simulation methods that have been developed will be incorporated in new releases of the LMS simulation software and potentially also in other simulation software. This will result in a competitive advantage of the LMS software and other software that will also exploit the research results.

List of Websites:
Contact person:
Dr Yves Lemmens
yves.lemmens@siemens.com
Interleuvenlaan 68
3001 Leuven
Belgium