Search

Abstract: During automotive related accidents, PVB plays an important role in both pedestrian and passenger protection as an interlayer of automotive windshield. In this paper, dynamic constitutive behavior of PVB material is thoroughly studied. Firstly, a set of dynamic compression impact experiments on PVB specimens using SHPB (Split Hopkinson Pressure Bar) method are conducted at strain rates from 700/s to 4500/s. Details of the constitutive response is analyzed based on the validation of experiment data. Stress-strain curve of PVB is then divided into two parts, i.e., “Compaction Stage” and “Hardening Stage”. Dislocations and entanglements among molecules are major reasons for the two-stage phenomena. Constitutive behaviors are different in low and high speed impacts, leading to three times more energy absorption ability of PVB in high speed impact scenario. Further, data fitting models based on both Mooney–Rivlin and Ogden Model are studied and then compared. Mooney–Rivlin Model is found to be more appropriate to describe PVB material. Moreover, PVB is proved to be a rate-dependent material with the failure strength intensify factor β ≈ 4. PVB material shows little viscoelasticity after comparison of the both models with and without the viscoelasticity part. Results offer critical experimental data, constitutive models and analysis of PVB material to further study of automotive crashworthiness and pedestrian/passenger protection. [ABSTRACT FROM AUTHOR]

Abstract: Windshield glass crack characteristics are of great interest to vehicle manufacturers, safety engineers, and accident investigators, because they contain important information on energy mitigation, pedestrian protection, and accident reconstruction. We use the extended finite element method (XFEM) to analyze the model problem of low-speed head impact on a windshield plate. Both the radial crack and circumferential crack propagations are characterized. A parametric study is carried out to investigate the effects of impact speed, head mass, initial material flaw, material fracture criterion, etc., and correlate them with the crack direction and length. It is found that the critical accident information, such as the impact speed or damage stress, can be deduced from the crack pattern characteristics. A qualitative bridge can be established between numerical simulation result and real-world accident via the crack growth mechanism. Our study shows that XFEM is a useful tool for simulating several types of cracks that appear during quasi-static indentation or low-speed impact of foreign objects on windshield materials. [Copyright &y& Elsevier]