Mechanical Performance of Fiber-reinforced Polymer Composites under Concurrent Hygrothermo-mechanical Loading

摘要

Fiber-reinforced polymer composites are used in a variety of engineeringrnstructures, where they may be subject to service conditions with concurrent static andrnfatigue mechanical loading, thermal fluctuations, moisture in water or service fluids.rnPredicting the durability of such materials in service conditions is critical to ensurernthat the appropriate condition-based maintenance routines are carried out, withrnconsequences on structural safety. In this work, sandwich composite samples arernmanufactured with unidirectional T700/vinylester skins and polyvinyl chloride (PVC)rnfoam core, using a conventional out-of-autoclave Vacuum Assisted Resin TransferrnMolding. The skin orientation selected for this study is 90 deg., to trigger a polymerdrivenrnresponse. Polymeric foam samples and sandwich composite samples wererntested under concurrent hygrothermo-mechanical loading in a custom-made testingrnapparatus, where displacements are obtained from resistance changes, which can bernmonitored continuously by digital multimeters. Specimens are immersed in deionizedrnwater at room temperature while being concurrently loaded in three-point bending, atrnset percentages of their dry ultimate static load. After immersion, the specimens arerntested to failure. A multi-scale model incorporating the time-dependent responses ofrnthe polymers in the sandwich skins and core is used to investigate the experimentalrnresults of this study. The multi-scale model consists of a micromechanics model forrnthe fiber-reinforced polymeric skins and layered beam elements, in order to predict therndeformations of sandwich composites under coupled mechanical and non-mechanicalrneffects.