Finite Fracture Mechanics crack initiation from a circular hole

Abstract

The brittle crack initiation from a circular hole in an infinite slab under uniaxial remote tensile load is investigated. The analysis consists of two parts. The former is focused on the difference between symmetric and asymmetric crack propagation. Different criteria in the framework of the Theory of Critical Distances are implemented, and the potentiality of coupled Finite Fracture Mechanics (FFM) approaches is highlighted from a theoretical point of view. The latter presents the experimental results obtained by carrying out ad‐hoc tensile tests on polymethyl‐methacrylate (PMMA) and general‐purpose polystyrene (GPPS) notched samples and the related FFM investigation. It is shown that FFM predictions are in very good agreement with the experimental results for both tested materials.

On the energetics of dynamic cohesive crack formation

“…2b and Fig. 3) where crack growth after initiation is unstable [2], the CZM simulations predict a continuous crack acceleration towards the Rayleigh wave speed (Fig. However of greater interest here shall be the subsequent fracture process which is represented in Fig.…”

“…2a) and tension (Fig. Further crack propagation is then identified as stable in case of compression and unstable in case on tension [2]. For both loading cases, FFM predicts the spontaneous formation of a finite crack increment ∆a from the quasi-static energy balance being satisfied in the mean over the fracture process.…”

“…For both loading cases, FFM predicts the spontaneous formation of a finite crack increment ∆a from the quasi-static energy balance being satisfied in the mean over the fracture process. In the following, length parameters are normalised utilising Irwin's characteristic material length l c := (K Ic /σ c ) 2 with K Ic = √ G c E as suggested in [2]. The notion of "spontaneous finite crack formation", inherent to FFM, is to be analysed here by solving the same boundary value problem by means of finite elements accounting for inertia effects as well as cohesive fracture.…”

“…Further crack propagation is then identified as stable in case of compression and unstable in case on tension [2]. The size effect of the fracture initiation load σ 0 , being a function of the hole radius, is known to be well captured by FFM [2]. A linear traction separation law is used for the CZM, analogous to that in Fig.…”

“…In the following, length parameters are normalised utilising Irwin's characteristic material length l c := (K Ic /σ c ) 2 with K Ic = √ G c E as suggested in [2]. The size effect of the fracture initiation load σ 0 , being a function of the hole radius, is known to be well captured by FFM [2]. Fig.…”