Dynamic fracture phenomena in high-strength steels

Abstract

Brittle metals subjected to blast loads shatter into a large number of very small particles, the number and size of which are well characterized by the semiempirical cumulative distribution function of Mott. This function, however, contains no information regarding either the manner of breakup or the reason for a particular distribution. An earlier analytical study of the phenomenology of brittle fragmentation used statistical arguments to establish relationships between the energies associated with crack branching and the Mott parameters that characterize the particle distribution. That model predicts that the average mass of a particle from the shattered body is proportional to the fourth power of the crack-branching stress-intensity factor. In the present work on hypereutectoid steels, the ratio (KH/KIC)3.4 was experimentally determined to be linearly related to the average particle mass in reasonably good agreement with the model prediction, where KH is the dynamic stress intensity factor for incipient microbranching (hackle), and KIC is the plane-strain fracture toughness.

A Tensile Origin for Fault Rock Pulverization

“…Our data sit about a line of not far from the average strength to fracture toughness ratio extracted from our data (i.e., with K IC = 1.79 MPa m 1/2 and the mean value of σ * ≈ 61 MPa, ), showing remarkably good agreement with theory. It is interesting to note that the experimental data of Weimer and Rogers () sits in the kinetic energy‐dominant realm, which may provide an explanation for the surprising result obtained by Glenn and Chudnovsky (). The success of GC in describing our experimental observations is reinforced in Figure b, where we compare the fragment size of each our experiments with predictions from equations and , as well as the Grady () model (equation ).…”

“…The agreement between GC and both experimental and numerical fragmentation data has been mixed. Glenn and Chudnovsky () compared the predictions of the full solution, equation , and the endmembers, equations and , to fragment size data from explosive fragmentation of brittle tool steel (Weimer & Rogers, ), and they found that the experiments were best fit by equation . In explaining this surprising result, Glenn and Chudnovsky () concluded that strain energy was essentially decoupled from the fragmentation process.…”

Mechanics of crack curving and branching ? a dynamic fracture analysis

“…The precise ultrasonic ripple marking technique used by Kerkhoff [36] also showed that the crack velocity decreased about 10 percent in glass immediately after branching, whereas Schardin [45] and Acloque [46] observed no change in crack velocities during branching in plate glass and a 6 percent change in pre-stressed glass, respectively. Crack branching velocities in various steels reported by Carlsson [47][48][49], Irwin [50], Hahn et al [51], Congelton et al [33][34][35], and Weimer and Rogers [52,53] were less than C/C1 = 0.25. A.S. Kobayashi et al [31,54,55], and Dally et al [8,32,56] studied crack branching using dynamic photoelasticity.…”

Crack Branching Characteristics at Different Propagation Speeds: From Quasi-Static to Supersonic Regime

“…However, many experiment works [4][5][6][7][8][9][10][11][12][13][14] on different materials indicate that the crack propagation speed observed is difficult to reach the limiting propagation velocity predicted by theory. Besides, numerical simulations, such as molecular dynamics (MD) [15,16], finite element method (FEM) [17,18], and extended finite element method (XFEM) [19], predict the similar phenom ena.…”