HICAS: High velocity impact of composite aircraft structures

• Forschungsstelle: EU FRP
• Projektnummer: 97.0467
• Projekttitel Englisch: HICAS: High velocity impact of composite aircraft structures

Schlüsselwörter (Englisch)

Composites; high-velocity impact; damage models; finite elements

Alternative Projektnummern (Englisch)

EU project number: CT97-0543

Forschungsprogramme (Englisch)

EU-programme: 4. Frame Research Programme - 2.1 Industrial and materials technologies

Kurzbeschreibung (Englisch)

See abstract

Partner und Internationale Organisationen (Englisch)

DLR, Stuttgart (Coordinator)

Abstract (Englisch)

The HICAS project is concerned with developing a design methodology for predicting the high-velocity impact response of composite aircraft structures. This is urgently required by the European aircraft industry since fibre reinforced composite materials are now being used increasingly in primary aircraft structures such as wings and aero-engines, where high-velocity impact such as bird strike or foreign objects can pose a serious risk to aircraft safety. Validated simulation tools are essential for the industry to reduce development costs, since impact tests on large aircraft structures are becoming too expensive to carry out at the development stage.
SMR has developed the numerical algorithms for the material models developed by the University of Linkoping and the DLR. These algorithms have been implemented in the finite element program B2000. The code was then released to the NLR for validation and simulation of specimen and impact tests. With the Linkoping UD material model, using the material parameters provided by U. Edlund (LINK), specimen tests and gelatine impact have been simulated by SMR/NLR using the B2000 code. A new gelatine model has been implemented by SMR for this purpose.
The results of these simulations were promising, but demonstrated the difficulty of obtaining the proper material parameters for both the UD damage model and the gelatine. To that end, an innovative idea has been proposed to use optimisation techniques combined with explicit dynamic simulations to match experimental and numerical results. The optimisation module of the B2000 code has been extended to include the analysis of the explicit dynamic simulations. This allowes the user to use material parameters as desging variables. In order to obtain the proper material parameters of complex material models, like the Linkoping UD damage model, the difference between the measured and numerial results of a (set of) material tests can be optimised. The proof-of-concept demonstrated the viability of this approach, but it will need further development outside the HICAS project.
For exploitation, SMR has been asked to help with the creation of some scientific papers by the University of Oxford and of Linkoping. It will also use the large-scale impact simulation as a benchmark abd demonstration of the capabilities of the code. Part of the finencial investment will be returned by increased sale of the B2000 finite element environement. Currently the DLR Stuttgart in in the process of aquireing a license, while the University of Oxford and of Linkoping have also shown interest.
The mesh of a uni-directional 90° ply specimen model, as used in the specimen tests is displayed in Figure 1, which also shows displacement solution. Figure 2 depicts the corresponding force on the output bar. The simulation produced results which corresponded reasonably with the experimental results. The optimisation technique described above is needed to improve these results. To illustrate the dynamic process, a snapshot during the simulation of gelatine impacting and penetrating the composite structure is displayed in Figure 3. This simulation corresponds to actual impact tests performed by the University of Oxford.
A more detailed synthesis of the result of this project can be found in the Synthesis Report published by the HICAS consortium. A copy of this report has been delivered together with this document

Datenbankreferenzen (Englisch)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 97.0467