The DeMAnD project has been set up to carry out a mechanical material characterization program to deliver a dynamic material property data base for typical aircraft materials, with a special focus on seat and crash absorbing structures of small aircraft. This dynamic material characterization will be carried out over a wide range of strain rates, ranging from quasi-static loading up to high strain rates of 500 s-1. For the various strain rate regimes, the best suitable test equipment has been identified and is available within the consortium. This will ensure the determination of high quality material data and complete stress-strain curves from static up to high strain rate loading, allowing the derivation of the strain rate dependent material behavior for all material properties needed for predictive crashworthiness simulations.
The DeMAnD project is carried out in context of the Transverse Activity (TA) “Small Air Transport (SAT)” and ITD Systems under Work Package WP 7.5 – Comfortable and safe cabin for small aircraft, more specifically: WP 7.5.2 – Advanced structural design of crashworthy configurable seats. As outlined in the CS2 work plan, “systems and equipment have to increase their intrinsic performance to meet new aircraft needs without a corresponding increase in weight and volume.” By understanding the material behaviour of the structural materials used in aircraft seats and its respective crash absorbing structures from static to high strain rate loading up to strain rates of 500 s-1, and by providing the needed material data input for FE-simulations, the aircraft seat structure design can be optimised in the following sense:
- A better material data input enables a better prediction of the structural response under dynamic loading. In this way the design can be optimised via simulation and expensive and time consuming structural tests can be minimised.
- The materials used in the aircraft seat structure can be tailored to the applied dynamic load, resulting in a more efficient material selection and exploitation. Consequently in an improved safety for flight personal and likely in a reduction of structural weight. This in turn leads to significant fuel savings and thus a beneficial environmental impact. This project mainly contributes to reach the TA WP 7 high level objective: “Safety and Security”.
The overall and specific objectives of the DeMAnD project are as follows:
1. Determination of strain rate dependent material behaviour for typical structural aircraft seat and crash absorber materials (metal alloys, fiber-reinforced polymer composites, foams).
2. Efficient, yet complete coverage of strain rate regimes ranging from quasi-static loading up to strain rates of 500 s-1.
3. Development of new specimen geometries and methodologies, most suitable for the dynamic loading of the materials selected in the project.
4. Determination of the complete stress-strain response for the materials and strain rate regimes selected in the project.
5. Determination of strain rate trends for relevant material properties (e.g. modulus, strength and failure strain, if applicable).
