Lifetime assessment of load-bearing polymer glasses : an analytical framework for ductile failure

The most widespread application of polymers in structural applications is their useas pipe material for e.g. gas distribution systems. Pipes have a design lifetime oftypically 50 years, which rules out real-time lifetime assessment methods. Here, anengineering approach is presented, whichmakes it possible to predict long-term ductilefailure of loaded glassy polymers based on short-term tests. The approach is basedupon the hypothesis that failure is governed by accumulation of plastic deformation upto a critical strain. A pressure-modified Eyring relation is employed to calculate theaccumulation of plastic strain for any simple loading geometry. It is demonstrated that the approach can produce accurate quantitative time-to-failure predictions for loadedPC specimens and uPVC pipe segments.