NUMERICAL-SIMULATION OF A HIGH-VELOCITY IMPACT ON FIBER-REINFORCED MATERIALS

Whereas the calculation of a high velocity impact on isotropical mater ials can be done on a routine basis, the simulation of the impact and penetration process into nonisotropical materials such as reinforced c oncrete or fiber reinforced materials still is a research task. We pre sent the calculation of an impact of a metallic fragment on a modern p rotective wall structure. Such lightweight protective walls typically consist of two layers, a first outer layer made out of a material with high hardness and a backing layer. The materials for the backing laye r are preferably fiber reinforced materials. Such types of walls offer a protection against fragments in a wide velocity range. For our calc ulations we used a non-linear finite element Lagrange code with explic it time integration. To be able to simulate the high velocity penetrat ion process with a continuous erosion of the impacting metallic fragme nt, we used our newly developed contact algorithm with eroding surface s. This contact algorithm is vectorized to a high degree and especiall y robust as it was developed to work for a wide range of contact-impac t problems. To model the behavior of the fiber reinforced material und er the highly dynamic loads, we present a material model which initial ly was developed to calculate the crash behavior (automotive applicati ons) of modern high strength fiber-matrix systems. The model can descr ibe the failure and the postfailure behavior up to complete material c rushing. A detailed simulation shows the impact of a metallic fragment with a velocity of 750 m s-1 on a protective wall with two layers, th e deformation and erosion of fragment and wall material and the failur e of the fiber reinforced material.