Effect of loading rate on dynamic fracture initiation toughness of brittle materials

Abstract

Numerical simulation is carried out to investigate the effect of loading rate on dynamic fracture initiation toughness including the crack-tip constraint. Finite element analyses are performed for a single edge cracked plate whose crack surface is subjected to uniform pressure with various loading rate. The first three terms in the Williams' asymptotic series solution is utilized to characterize the crack-tip stress field under dynamic loads. The coefficient of the third term in Williams' solution, A 3 , was utilized as a crack tip constraint parameter. Numerical results demonstrate that (a) the dynamic crack tip opening stress field is well represented by the three term solution at various loading rate, (b) the loading rate can be reflected by the constraint, and (c) the constraint A 3 decreases with increasing loading rate. To predict the dynamic fracture initiation toughness, a failure criterion based on the attainment of a critical opening stress at a critical distance ahead of the crack tip is assumed. Using this failure criterion with the constraint parameter, A 3 , fracture initiation toughness is determined and in agreement with available experimental data for Homalite-100 material at various loading rate.

Quasi-static and dynamic fracture behaviour of rock materials: phenomena and mechanisms

“…Thus, the observed increase in crack initiation toughness is attributed to the time required to reach a critical stress state ahead of the crack tip over a critical distance. The similar investigations on the effect of loading rate were conducted by Kalthoff (1986) who predicted the existence of an incubation time for crack initiation and by Kim and Chao (2007) who proposed a crack-tip constraint model. Liu et al (1998) analytically modelled the experimental measurements of Ravi-Chandar and Knauss (1984a) for Homalite-100 material by estimating the critical SIF on the basis of different critical distance δ.…”

A combined experimental–numerical investigation of fracture of polycrystalline cubic boron nitride

“…Both Belenky et al [17] and Kim and Chao [19] reported significant increases in fracture toughness at increased loading rates for monolithic ceramics.…”

The effect of a pre‐existing crack on a running crack in brittle material under dynamic loads

“…Fracture behavior of brittle material with innate flaws has attracted much attention recently. Extensive researches on crack initiation, propagation and coalescence have been conducted by using the specimens containing single flaw or multiple flaws in either artificial materials or real rocks under static loads, 1-6 impact loads [7][8][9][10][11][12][13][14][15][16] or blasting loads. 17 Classical fracture mechanics has gone so far as to answer a large number of questions about fracture behavior under various kinds of loads, but for the issue of a running crack approaching a pre-existing crack, there still remain a multitude of unanswered or partially unanswered aspects, such as how the pre-existing crack would affect the running crack?…”