Influence of loading rate on dynamic fracture behavior of fiber-reinforced composites

Abstract

The effect of loading rate on the dynamic fracture properties and the failure mechanisms of glass fiber-reinforced composite materials under mode I fracture is studied. Dynamic reflective caustic experiments are carried out for two loading rates. By measuring the characteristic dimensions of the shadow spots during the caustic experiments, the dynamic SIFs are calculated for different loading rates. The experimental results indicate that the dynamic fracture toughness K Id increases remarkably with increasing loading rate, and the crack grows faster under the high-velocity impact. Moreover, by examining the crack growth routes and the fracture surfaces, it is shown that the loading rate also greatly affects the failure mechanisms at micro-scale.

Dynamic Fracture Toughness: Critical Review of Materials and Developments

“…Syn [42] used four point bending specimens with a precrack, loaded dynamically at high rates to investigate loading rate and surface topography effects on energy dissipation during dynamic fracture of an aluminum/epoxy interface. Gong [43][44] applied Caustics method technique in FM to resolve dynamic fracture problems in orthotropic composites because of its high sensitivity to stress gradients. Crack onset time, DFT and crack growth velocity of orthotropic composite are determined with the help of shadow spot patterns.…”

Recent application of caustics on experimental dynamic fracture studies

“…investigated the dynamic fracture toughness and the crack growth velocity of polypropylene/nylon‐6 (PP/PA6) blends with different weight fractions and different compatibilizers by means of the reflected dynamic caustic experiments. Gong et al 37–39 . studied dynamic mode I and mixed‐mode fracture problems of typical glass fibre‐reinforced composites using the caustics, which indicated that the arrangement of fibre has a larger influence on the fracture process than the volume ratio of fibres.…”

“…studied the dynamic fracture toughness of six modified cement rock specimens by means of reflective dynamic caustics, which indicated that the fibre reinforcement is an effective way to improve the impact resistance of cement rocks. In Refs [36, 37 and 40], was applied to calculate the stress intensity factor at the crack tip. But cannot reflect the influences of the anisotropy term in composite materials.…”

“…But cannot reflect the influences of the anisotropy term in composite materials. So those results were approximate solution in Refs [36,37 and 40]. In order to solve complex caustic equations of composite materials, both the characteristic size and its relevant angles were introduced to obtain the stress intensity factor in Ref.…”

“…Li et al 36 investigated the dynamic fracture toughness and the crack growth velocity of polypropylene/nylon-6 (PP/PA6) blends with different weight fractions and different compatibilizers by means of the reflected dynamic caustic experiments. Gong et al [37][38][39] studied dynamic mode I and mixed-mode fracture problems of typical glass fibre-reinforced composites using the caustics, which indicated that the arrangement of fibre has a larger influence on the fracture process than the volume ratio of fibres. Wang et al 40 studied the dynamic fracture toughness of six modified cement rock specimens by means of reflective dynamic caustics, which indicated that the fibre reinforcement is an effective way to improve the impact resistance of cement rocks.…”