Recent developments in stress relaxation methodologies within Europe

This paper sets out some of the findings arising from a recent programme of work investigating stress relaxation testing. It reviews current standards and examines the equipment capabilities necessary for successful testing. Inter and intra laboratory variability of data is examined, as is the impact of influences such as loading methods. A means of re-starting previously tested testpieces is described and validated. The need for modulus determinations is explored and a model is used to assess extensometer performance requirements. Recommendations are made as to improvements to the stress relaxation test; these will form the basis of a new Euronorm to address stress relaxation testing.