Search

The mechanical behavior of polyvinyl butyral (PVB) significantly influences crashworthiness and energy mitigation abilities of windshields in terms of pedestrian safety. In this article, mechanical characteristics of PVB are experimentally studied. First, tension and compression experiments on PVB specimen are carried out under various quasi-static loading rates. Fundamental mechanism of rate-dependent behavior is investigated. Besides, dynamic tension and compression experimental data are compared to investigate the mechanical behavior of PVB in a whole strain rate region and it is found that PVB behaves as a viscoelastic material under compressive loadings in both quasi-static and dynamic situations; however, intension experiments, stress-strain curves of PVB under dynamic loadings are elastoplastic while those under quasi-static loadings are viscoelastic. Considering all the unique characteristics of PVB's behavior, constitutive models are then established based on Zhu-Wang-Tang model mathematically. Further, unit volume energy absorption of every experiment in quasi-static tension and compression are calculated as well as the stress intensify factor. In addition, visco-elasticity part in the constitutive model is employed. Results may offer useful experiment data and important constitutive characteristics of PVB material to further studies of automotive crashworthiness and pedestrian protection. POLYM. ENG. SCI., 52:1137-1147, 2012. © 2012 Society of Plastics Engineers, INTRODUCTION PVB, the abbreviation of polyvinyl butyral, is a polymer material with excellent adhesive property, optical clarity, toughness and flexibility [1]. Nowadays, PVB becomes the prior choice of the interlayer [...]

A numerical strategy, based on continuum damage mechanics and the failure envelope method, is proposed for failure prediction of composite multi-bolt joints. First, the design parameters of the failure envelope are determined by virtual tests of simple structures. Then, a modified failure envelope incorporating the bending effect is constructed. Finally, different bearing-to-bypass stress ratios and the influence of bolt rows on the bending effect are discussed. It is shown that the failure envelope with constant bearing-to-bypass stress ratio, obtained by assuming uniform bolt load distribution, is recommended. And the bending effect of single-lap, composite multi-bolt joints is alleviated by the introduction of more bolt rows. These results indicate that failure prediction of composite multi-bolt joints, using the proposed numerical strategy, exhibits excellent agreement with the experimental outcomes. This demonstrates that the numerical strategy is feasible. [ABSTRACT FROM AUTHOR]