The time-dependent mechanical properties of fibre reinforced polymers

Abstract

1. General Progress The six months from April to September 1969 have been spent mainly in consolidating the work of the previous eighteen months. Firstly, due to major servicing problems, it became necessary to redesign the resin impregnating head of the filament winding machine. By the removal of all moving parts from the vicinity. of the resin, these servicing problems have been completely overcome. Using the redesigned machine many sheets of high quality glass reinforced epoxy resin have been produced. A sophisticated version of the spring mounted lateral extensometer described in Progress Report No. 3 has been designed and tested. Six of these have now been produced and are now in service yielding satisfactory results. The majority of the period has been spent in setting up the tensile creep testing machines. This has been necessitated by the discovery that errors of up to 10% in creep compliance have been obtained through misalignments of the loading linkages of the order of .01 inch. All the apparatus is now functioning correctly and more creep results for uni- and bi-directionally reinforced specimens are being obtained. Included in these current creep results are not only values for creep compliances but also for the creep contraction of these specimens.