Strain rate dependent multiaxial characterization of long fiber reinforced plastic

The Effects of Strain Rates on Mechanical Properties and Failure Behavior of Long Glass Fiber Reinforced Thermoplastic Composites

“…Since there is not yet a valid standard for the execution of the high-speed tensile tests for polymers or polymer matrix composites, the dimensions of the dynamic tensile specimen (named Type HS) were designed with reference to the ISO 26203-2 and ISO 527-2 norms. The Type HS specimen size was to achieve higher strain rates with the testing machine [1,22,25]. Both of the specimen thicknesses were 4 mm.…”

“…The specimen strains were determined using DIC and the evaluated strain values were obtained from the fracture strain of P 0 [25,34]. According to the true stress-strain curves of LGFRPPs, as presented in Figure 6, the LGFRPPs were strongly sensitive to the strain rates.…”

“…Since the interfacial debonding was the main micro-damage mode before specimen failure, the change of stress-strain response was mainly caused by strain rate sensitive failure behavior of interface properties which was attributed to the strain rate sensitivity of the fiber and matrix [39,40]. The specimen strains were determined using DIC and the evaluated strain values were obtained from the fracture strain of P0 [25,34]. According to the true stress-strain curves of LGFRPPs, as presented in Figure 6, the LGFRPPs were strongly sensitive to the strain rates.…”

“…The fiber orientation distributions due to the injection molding process determined the anisotropy of the material. The sandwich structure might have a certain influence on the mechanical behavior of LGFRPPs [25]. The typical fracture surface images of LGFRPPs under low, medium, and high strain rates are shown in Figure 12.…”

“…It could be seen from the white sphere that, at high strain rates, the PP matrix underwent local melting due to local adiabatic heating, which resulted in better interfacial bonding between the matrix and fibers. Simultaneously, the adiabatic temperature rise enlarged the deformation zone, impeded strain localization, and led to higher energy absorption at higher strain rates [25]. Thus, the positive strain rate sensitivity of the interface between the matrix and fiber might be caused by the interfacial bonding properties and enhanced the energy absorption capacity.…”