MECHANICAL BEHAVIOR OF WOVEN THERMOPLASTICCOMPOSITES UNDER VARYING STRAIN RATES

摘要

Composite materials are increasingly replacing conventional materials in aerospace, marine, civiland automotive industries as a result of their high specific stiffness, strength, superior corrosionresistance and low coefficient of thermal expansion. To further increase their use, it is importantto have a deeper understanding of their mechanical response under varying strain rates. In thispaper a study of the mechanical behavior of thermoplastic woven composites was conductedunder varying strain rates ranging from 5.0 × 10~(-5) s-1 to 5.0 × 10~(-2) s-1 using a universal testingmachine. Comprehensive tensile testing was performed on samples with 50/50 fiber volumefractions in the warp and fill directions. Furthermore, fiber angles of 0° and 90° were used tohave a deeper understanding of the effect of fiber orientation and architecture in their mechanicalresponse under high loading rates. During tensile testing, a high resolution state of the art noncontactstrain measurement system was used to monitor real time-specimen deformation, strainevolution and distribution at varying strain rates. Experimental results provided stress vs. straincurves over the full range of loading rates highlighting the strain rate sensitivity exhibited by thethermoplastic composites. Furthermore, the non-contact strain measurement system revealed theeffect of fiber angle and woven architecture on the mechanical behavior of thermoplastic wovencomposites. A clear formation of strain concentrations was identified and a deeper insight in tothe global and local strain evolution and distributions within these woven composites wasachieved.