Simulation Analysis Of Frontal Collision Failure Of Automotive Plastic Water Tank Support Based On CrachFEM

With the development of materials technology and automotive lightweighting,short fiber reinforced composites are gradually being used in the automotive industry and the use is increasing year by year.The researches on the mechanical properties of short fiber reinforced composites are mainly based on experiments.The simulations are mainly to establish a micro-single-cell structure model with single-fiber or multi-fiber to study the forces transfer between fibers and matrix and the influence on fibers.while for short fiber reinforced composites There are few simulation studies on the macroscopic mechanical properties of materials.Using the constitutive models of materials existing in LS-DYNA,the constitutive models can not fully consider the mechanical properties of the material,such as the anisotropic,viscoelastic,dynamic strain rate of short fiber reinforced composites.LS-DYNA's 22# Materials can only consider anisotropy and dynamic strain rate.In order to comprehensively simulate the mechanical properties of the materials,this paper studies the mechanical properties of short fiber reinforced composites with fracture failure based on the CrachFEM failure model of German MATFEM.Based on the CrachFEM failure model theory,the uniaxial tensile tests of different fiber directions and different strain rates are carried out to study the anisotropy,viscoelasticity and dynamic strain rate effects of materials.At the same time,various fracture failure tests are carried out to study the fracture failure of materials.According to the uniaxial tensile test datas and the existing theories,the elastoplastic mechanical performance parameters of the material are fitted.According to the fracture failure test data and the CrachFEM failure model,the material ductile normal failure limit curves are fitted,and the short fiber reinforced composite material(PP+GF30)simulation card is edited.At the same time,the finite element model of uniaxial tensile test is established,and the uniaxial tensile test force and displacement curves of different fiber directions and different strain rate are simulated.Verify the material card's accuracy for the anisotropy,viscoelasticity and dynamic strain rate of short fiber reinforced composites.A finite element model of three-point bending and erichsen test are established,and the simulations of the force and displacement curves of the fracture failure test are performed.The fitting accuracy of the CrachFEM failure models to the fracture failure of short fiber reinforced composites is proved.The material card developed is a good description of the mechanical properties of the material.Based on the national standard GB 11551-2014 and GB/T 20913-2007,the finite element model of the 100% overlapping rigid wall crash and the frontal 40% overlapping deformable barrier crash finite element model are established.The material simulation cards of CrachFEM failure model,Constant strain failure model and GISSMO failure model are used to simulate the crash of the short fiber reinforced composite water tank bracket and analyze the fracture failure behavior of the water tank bracket.By analyzing the acceleration of the B-pillars and deformation of A-pillars,it can be seen that the short-fiber reinforced composite water tank brackets meet the requirements of the enterprise for the crash safety of the whole vehicle.