Elastic-Plastic Deformation in Surface-Cracked Plates: Experiment and Numerical Analysis

Abstract

Detailed three-dimensional nonlinear finite element (FE) analyses and experimental moire studies are performed on a plate containing a moderately deep part-through surface crack to establish limits of HRR-dominance. The plate is subjected to predominantly far-field tensile loading. The material under investigation is ASTM A710 steel, which was constitutively modeled by large deformation J2 flow theory of plasticity. The FE mesh was carefully constructed to resolve both crack front fields (such as J-integral and CTOD) and global fields (such as surface displacements, strains). By comparing the J-integral and CTOD results with an earlier HRR-dominance study using (small strain) deformation theory of plasticity, we found little effect of the different formulations on the crack front fields. The global deformation fields from the numerical simulation are in good agreement with our experimental results. The eventual loss of HRR-dominance is intimately related to the interaction of the global plastic flow fields with those of the crack front.

Investigation of crack-tip plasticity in high volume fraction particulate metal matrix composites

“…This confirms an earlier review by Parks [28] and agrees with the results discussed in [20,30,31] where FE analyses were compared with CTOA or CTOD measurements.…”

“…Indeed, it has been increasingly understood in the past decade that surface measurements are affected by 3-D effects [28][29][30], and that caution must be exercised in analysis of experimental data. For instance, it has been shown that plane-stress approximations are not sufficient to fit experimental measures such as the crack-tip opening angle (CTOA) or the crack-tip opening displacement (CTOD) (which are the surface measurements of crack-tip loading that are the most commonly performed), whereas 3-D analyses yield much better agreement [20,[30][31][32].…”

“…To the best of our knowledge, such comparisons between elastic-plastic strain fields observed by experiment and numerically computed have rarely been performed. Three-dimensional constraint effects have, rather, been assessed by correlating numerical computations with other measurements, which are more directly accessible such as the CTOA, the CTOD or load-displacement curves [20,[31][32][33][34][35][36]. A second goal of this investigation is therefore to evaluate the significance of three-dimensional ''constraint'' effects with these half-metal/half-ceramic composite materials.…”

“…In order to obtain the total elastic-plastic strain field (and, in turn, the boundary with the crack-tip plastic zone) in elastoplastic materials other techniques are generally used, such as stereoimaging [18], Moire interferometry [19,20], or laser-speckle interferometry [21][22][23]. By contrast, because photoelasticity provides only the elastic strain fields in the birefringent coating, it is mainly used to determine experimentally stress intensity factors for complex loading modes in components where the fields are predominantly linear elastic [24][25][26][27].…”

Investigation of crack-tip plasticity in high volume fraction particulate metal matrix composites

“…In order to obtain the total elastic-plastic strain field (and, in turn, the boundary with the crack-tip plastic zone) in elastoplastic materials other techniques are generally used, such as stereoimaging [18], Moir e interferometry [19,20], or laser-speckle interferometry [21][22][23]. By contrast, because photoelasticity provides only the elastic strain fields in the birefringent coating, it is mainly used to determine experimentally stress intensity factors for complex loading modes in components where the fields are predominantly linear elastic [24][25][26][27].…”