Determining Material Response for Polyvinyl Butyral (PVB) in Blast Loading Situations

Protecting structures from the effect of blast loads requires the careful design of all building components. In this context, the mechanical properties of Polyvinyl Butyral (PVB) are of interest to designers as the membrane behaviour will affect the performance of laminated glass glazing when loaded by explosion pressure waves. This polymer behaves in a complex manner and is difficult to model over the wide range of strain rates relevant to blast analysis. In this study, data from experimental tests conducted at strain rates from 0.01 s−1 to 400 s−1 were used to develop material models accounting for the rate dependency of the material. Firstly, two models were derived assuming Prony series formulations. A reduced polynomial spring and a spring derived from the model proposed by Hoo Fatt and Ouyang were used. Two fits were produced for each of these models, one for low rate cases, up to 8 s−1, and one for high rate cases, from 20 s−1. Afterwards, a single model representing all rates was produced using a finite deformation viscoelastic model. This assumed two hyperelastic springs in parallel, one of which was in series with a non-linear damper. The results were compared with the experimental results, assessing the quality of the fits in the strain range of interest for blast loading situations. This should provide designers with the information to choose between the available models depending on their design needs

A Three-Dimensional Constitutive Model for the Dynamic Response of Rubber3

The development of a constitutive model to describe the dynamic response of a filled rubber compound is presented in this paper. A series of cyclic tension tests were done on the rubber compound with mean strains ranging from 0.2 to 0.5, strain amplitudes ranging from 0.05 to 0.2, and strain rates ranging from 0.1 to 10 s−1. The cyclic strain-controlled test results showed material rate dependence and hysteresis, and this motivated the development of a phenomenological-based, hyper-viscoelastic constitutive model. A Zener model, i.e., a spring in parallel with a Maxwell element, was assumed. The total stress was decomposed into a rate-independent equilibrium stress and a rate-dependent overstress. The springs were modeled as neo-Hookean, while the damper was defined by a nonlinear viscosity function. Material constants for the constitutive model were calculated from the cyclic tension test results. Cyclic tension tests were also performed on a sheet with central hole to check the accuracy of the constitutive model. The constitutive model was implemented into ABAQUS Standard with a user-defined material subroutine. The finite element analysis simulation of the rubber sheet with a central hole demonstrated relatively good agreement with the experimental data