Abstract
Commercial headlamp outer lens is made of polycarbonate material which is inexpensive, provide necessary optical and mechanical properties and is chemically stable. During head-form impacts, the headlamp lens is observed to fracture in a near-brittle manner unlike the parent polycarbonate (PC) which is known to exhibit significant ductility. The headlamp housing on the other hand is injection molded using talc-filled polypropylene-polyethylene copolymer (PP) which has different failure properties. Capturing deformation and fracture behavior accurately in CAE is a prime requirement to give accurate engineering solutions to the designer. Although the traditional MAT024 model is a robust and computationally efficient, it assumes Von Mises yield criteria which is an incomplete way of representing pressure sensitive materials like polycarbonate and polypropylene. In the present work, LS DYNA advanced material MAT_SAMP is defined by characterizing the chosen materials in tension, compression and shear using standard methods at different strain rates. A realistic yield surface for the polymers is generated and incorporated in the material model to represent the headlamp components facing complex stress states. Validation of the CAE model is done comparing the CAE results with those from test and good correlation is reported. A test rig is designed which has the flexibility to simulate different boundary conditions for headlamps belonging to different vehicle programs.