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The present paper investigates the effect of temperature of unplasticized polyvinyl chloride (UPVC) under tension. UPVC specimens were tensile tested across a range of temperatures (from À20 C to 60 C). The UPVC, like other polymers, was strongly affected by temperature. Those below room temperature were more fragile but had greater tensile strength and stiffness. When room temperature is exceeded, the UPVC test specimens became softer, with lower strength and stiffness. Considering the results, an analytical expression to predict the mechanical behavior of UPVC in tensile tests at different temperatures-more specifically a description of the experimental tensile stress-strain curves by an algebraic equation is proposed. A reasonable approximation of the stress-strain curve was possible to obtain with a minimum of three tests performed at different temperatures. The analytical results were in good agreement with experimental ones.

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Two mechanical models have been presented in this paper for structural failure prediction of piping systems conveying liquids subjected to pressure transients. One model takes into account the axial fluid–structure interaction (FSI) phenomenon between fluid and pipe motion, whereas the other refers to an extension of the well‐known waterhammer formulation. Both models are described by a system of non‐linear hyperbolic equations which are solved by using a numerical procedure based upon the operator splitting technique and Glimm's scheme. To implement Glimm's method, it is presented the solution of a 4×4 Riemann problem with discontinuous coefficients. Numerical predictions of both models are presented and compared, so that the influence of the FSI term on the failure analysis is focused on. © 1998 John Wiley & Sons, Ltd.

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