Development Of High-precision Numerical Algorithms For The Impact Fracture Analysis Of Automotive Windshield Glass And The Related Engineering Applications

Automotive laminated glass is normally sandwiched by two soda-lime glass layers and one polyvinyl butyral(PVB)layer under high temperature and pressure.Because of loading capacity,energy absorption,and good optical properties,laminated glass has been widely used in vehicles as windshield glazings.The pedestrian-vehicle accidents are increasing along with the rise of vehicle number.Therefore,it is of vital importance to investigate the effects of impact damage of windshield glass on the safety of pedestrians and drivers.With the rapid development of computer technology,the numerical simulation methods have found wide applications in the study of the impact failure of automobile windshield.The so-called cohesive zone models are attractive for crack simulations.At present,many commercial codes,such as LS-DYNA,have incorporated intrinsic cohesive zone models.The intrinsic cohesive elements are inserted into the common surface between two solids or common edge between two shells prior to simulations,thereby greatly increasing the computational cost and storage.In view of this,we propose a cohesive shell model,where cohesive elements are adaptively inserted into the finite element(FE)model along with crack growth,to describe impact failure of automotive windshield.First,a HLSR shell element is developed.A cohesive shell element that calculates cohesive forces via a virtual cohesive face is proposed to simulate the failure between shell elements.During simulation,the cohesive elements are adaptively inserted into FE model.A new topological data structure is developed based on the so-called Tops data structure by introducing a concept of edge status.The proposed data structure is compared with the Tops in terms of storage and computational efficiency.Finally,the effectiveness of the proposed cohesive shell model is validated by means of several representative numerical examples,such as three point bend of a glass plate,concrete crushing,and tearing of an aluminum plate.Then,an edge-edge contact approach is developed to properly describe the interaction between glass cracks.A single surface contact algorithm is developed for the interaction between impactor and glass fracture based on the conventional single surface contact algorithm.The bonding between glass and PVB is described via a developed tied contact method,which cannot be described by the conventional tied contact algorithm due to the adaptive duplication of nodes.An improved tie-break algorithm is developed to model the delamination between glass and PVB.Several simple examples are performed to validate the effectiveness of the proposed contact algorithms.Finally,the developed numerical framework is implemented in the open source code,DYNA3 D,by using Fortran77 language.The numerical framework is applied to the impact fracture simulations of a laminated glass plate and a windshield glazing subjected to an impactor and a headform,respectively.The simulation results are found to be in good agreement with the experimental ones,which validates the capacity of the computational framework in impact fracture analysis of laminated glass and windshield glass.Furthermore,the failure mechanism of laminated glass plate and the impact failure characteristics of windshield glazing are analyzed.The effects of the meshes,impact velocity,impact angle,constraints,and impact points on the impact fracture behavior of automotive windshield are numerically investigated.