Shear Lag in High-Throughput Testing of Thin-Ply Composites

High throughput testing methods have significant potential to reduce experimental efforts in determining mechanical, time-dependent, and multifunctional properties with reduced time and cost. Imposing a known stress gradient on the gauge length of the test coupon is one of the most recent test methodologies. The stress gradient based high throughput testing scheme is well proven for low density polymers and the off-axis unidirectional composite laminates. However, the shear lag due to interfacial interaction between the loaded and the unloaded fibers in 0°UD composite laminates is still a challenge, which limits the scope of high throughput testing. Based on our previous experimental learnings, this paper is an analytical and computational attempt to circumvent the shear lag that varies from the boundary to the middle region of geometrically tailored test specimen. The study shows that the shear lag in trapezoidal specimen with an imposed stress gradient could be restricted to the boundary only, thereby holding a uniaxial state of stress in the middle zone for high throughput data extraction.