Community Research and Development Information Service - CORDIS


BLADEOUT Report Summary

Project ID: 686813
Funded under: H2020-EU.

Periodic Reporting for period 1 - BLADEOUT (CROR Blade-Out Impact Simulations and Sample Manufacturing)

Reporting period: 2016-01-01 to 2016-12-31

Summary of the context and overall objectives of the project

The development of counter rotating open-rotor (CROR) aircraft engines is a key objective of the CleanSky program. Significant fuel saving can be achieved by CROR engines compared to modern turbofans because of the ultra-high bypass ratios, and the elimination of aerodynamic drag and weight related to large nacelles. However throughout the life cycle of an aircraft, an uncontained blade-out failure is likely to be encountered due to probable malfunction or blade failure, inadequate rotor design, fatigue, material imperfections, assembly errors and foreign object impact damage. Unlike a typical engine configuration where blade loss is mitigated with fan case containment, an uncontained CROR blade failure can lead to high energy blade impact on the fuselage and catastrophic failure. The faced challenge for the CROR concept is to maintain the current level of safety mandated by aviation and certification regulations and to provide blade impact mitigation at the airframe level without resulting in a large weight penalty. This leads to a demanding impact analysis and design problem of two complex composite structures, the CROR blade or fragment structure (impactor) and the fuselage structure (target), which should be designed to withstand a high-energy impact at minimum weight penalty to the aircraft.

Undoubtedly, the adequacy and safety of a shielding structure will be finally demonstrated through experimental procedures. However, a financially sustainable and time efficient design procedure requires the development of advanced numerical analysis models, which are rather complex due to the high velocity and complex impactor (blade) geometry, and which can be used to design and simulate the impact of both the shielding and the blade structure.

The main goal of the proposed research is to develop a robust, computationally efficient, multi-scale numerical simulation model, based on ABAQUS EXPLICIT FE solver, for the virtual-testing of partial (sectioned blades) and scaled CROR blade impacts. The envisioned modelling tool should address issues rising during the design and simulation of CROR blade impact and the airframe shielding. Following common practice, a building block approach will be employed to validate its predictive capabilities with respect to impact behaviour for both the blade and the shielding structure. Thus, the objectives of the project can be outlined as:

Obj. 1: Design of Representative Blade Specimens (85% Complete). Partial composite blade sections were designed and full CROR composite blades is work in progress. The selection of composite materials is also a current activity in order to design internal blade structures for optimal conformation to project requirements and certification procedures.

Obj. 2: Development of Multi-Scale explicit impact Finite Element Models (85%). Based on previous experience of Consortium and findings for current designs, computationally efficient explicit FEA models are being developed for the simulation of CROR composite blade impacts.

Obj. 3: Manufacturing of Representative Specimens (10%). The preparation of RTM mold and system for composite plates fabrication (specimens for characterization and low level impact testing) was completed. Upon completion of the previous objectives, a series of representative specimens will be manufactured using RTM process based on a building-block approach; i.e. ranging from simple characterization specimens to representative scaled blade components.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Conclusions for the First Reporting Period

The project is underway and initial blade design and impact scenarios have been performed. The analytical and FE models of the blade, with its initial layup design, show good correlation with Airbus requirements. Initial impact models have been developed for both plate, scaled blade and full scale blade model.

For the Initial Blade Design, three admissible material and lamination scenarios have been determined, in compliance with requirements set by Airbus. These scenarios include the following conceptual cases: (1) single material & uniform section layup, (2) multiple materials & uniform section layup, and (3) multiple materials & stiffened sections. One of the scenarios with both fabric and unidirectional materials was chosen as the best candidate from meeting the requirements better.

The material was numerically characterized using IM7/RTM-6 laminates with (0/90W) & (±45W) layups were successfully characterized as were unidirectional IM7/RTM-6 properties. Methodology and theory was also discussed in deliverable reports.

The blade design was enhanced with additional reinforcement layers on the FE model and Rohacell HT71 foam inside the blade and was shown to meet all stiffness requirements for flapping, lead-lag, tension, and torsion.

Impact simulation of impactors on blade and plate models with different laminates have been performed. Lessons will be carried forward onto blade impact models on curved panel structures.

The project with continue with impact simulation of the full and scaled FE models for design refinement and impact assessment. Specimens will be manufactured and tested for further characterization. Several slightly scaled Blades and ten (10) Partial Blade components sections from root, mid, and tip, will be manufactured and delivered to Airbus Defense and Space.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The BLADEOUT Project was inspired to have a major effect on the development of CROR engines. The CROR concept is very promising because of the fuel efficiency aspect, however hazards related to possible blade impact scenarios can reduce the global economic efficiency of the entire aircraft due to additional weight needed for shielding purposes. The envisioned methodology is targeting three major directives: Performance, Efficiency and Safety.
Upon completion, the proposed impact investigation approach will enable realistic simulations of blade impact events. The methodology is robust in terms of internal section geometries, laminations architectures (UD, stitched, woven, braided), fibre/resin material combinations, and considers damage and fracture behaviour, thus making this methodology suitable for design purposes of both the blade and shielding structures.

The activities performed so far are in the direction of accomplishing the envisioned impacts:
• The lamination design (material and selection and layup) is compatible with current performance requirements, while being efficient in terms of strength, cost and weight.
• The proposed approach based on numerical simulations instead of a massive experimental campaign, enables an economical and efficient CROR blade design process, potentially leading to lower product development turn-around-time, and better products in terms of performance over weight ratios due to in-depth knowledge of the energy absorption and damage/fracture mechanisms.
• Planned investigations of impact of CROR blade fragments will further assist towards the development of lighter airworthy blade/airframe shielding systems.
• The use of validated RTM manufacturing methodologies ensures low manufacturing costs, high-production rates and repeatable net-finish quality.
• An innovative set of impact scaling laws are being developed that will help predict full scale model impact behavior (impact damage and damage mechanisms) when only a scaled model can be tested. This can be utilized to save time and money when certifying blade for impact requirements.
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