↓ Crash-Simulation

↓ Impact-Simulation

Crash-Simulation

In order to increase the safety in case of crash loads energy absorption elements are applied in a structure. The aerospace and automotive industry commonly uses metallic structures with high plasticization energy absorption potential for these structural elements. A further approach offers the implementation of fiber composite materials. Due to the progressive failure behavior they have clearly higher relative density values than metallic structures.

For the methodical design of these structures the IFB develops numerical approaches in PAM-CRASH and NASTRAN as well as corresponding test methods. While for an impact defect the delamination leads to a reduction of the residual strength, for axial crushing the progressive failure behavior of fibers and matrix fracture is used to absorb the energy.
The figure on the right hand side shows an example of a drop tower test with a composite part.

For a detailed demonstration of the energy absorption behavior a calculation methods for meso-models which describe the important failures like fiber fracture, matrix failure and delaminations is created. With a test rig developed by the IFB models are calibrated in order to describe the tests at the component level.
The figure shows the numerical analysis of the drop tower test with a corresponding meso-model.

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Impact-Simulation

Besides the energy absorption the structural behavior due to perpendicular impacts is of importance. Abrupt loads can lead to separation of individual layers. These delaminations can have a considerable influence to the residual strength. In order to have efficient applications for composite structures in a crash structure both load cases have to be considered and represented virtually.

Impact on sandwich structures must be recognized more critical than impact on monolithic structures. On the one hand is the wall thickness of the face sheets usually smaller than the wall thickness of monolithic structures. On the other hand the bonding of face sheets onto the core is a weak point. And failure of the bonding can cause catastrophic damage. The impact performance of sandwich structures with foldcores is therefore tested in gas-gun tests. A modelling method for simulation of these tests is developed in parallel. An example for execution and simulation of these tests is shown in the figure on the right hand.

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