Modern topics and challenges in dynamic fracture

Cox, Brian N.; Gao, Huajian; Groß, Dietmar; Rittel, D.

doi:10.1016/j.jmps.2004.09.002

Cited by 113 publications

(47 citation statements)

References 162 publications

(150 reference statements)

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“…The normalized crack velocity, v/c R , vs. crack position is shown in Figure 2. 3 At the lower loading of G/G Ic = 1.27, dynamic cracks encountering the more-brittle materials (G Ie /G Ic = 1.72, 2.10, 2.53) grow dynamically into the second material while remaining atomically sharp, although the steady-state velocity may change. The velocity decreases with increasing G Ie , echoing previous findings that cracks in "softer," longerrange potentials typically attain lower steady-state velocities [15,46].…”

Section: Dynamic Cleavage In 2dmentioning

confidence: 99%

“…Cracks initiate in the brittle phase and should be arrested when they encounter the ductile phase. Since such cracks run dynamically in the brittle phase after initiating from pre-existing flaws, the dynamic response of the system may govern the macroscopic "quasi-static" toughness [2,3]. One important example is mild steel, where cracks develop within grain boundary carbides and propagate dynamically toward the primary α-ferrite grains.…”

Section: Introductionmentioning

confidence: 99%

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Crack tip blunting and cleavage under dynamic conditions

Rajan

2016

Journal of the Mechanics and Physics of Solids

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In structural materials with both brittle and ductile phases, cracks often initiate within the brittle phase and propagate dynamically towards the ductile phase. The macroscale, quasistatic toughness of the material thus depends on the outcome of this microscale, dynamic process. Indeed, dynamics has been hypothesized to suppress dislocation emission, which may explain the occurrence of brittle transgranular fracture in mild steels at low temperatures [1]. Here, crack tip blunting and cleavage under dynamic conditions is explored using continuum mechanics and molecular dynamics simulations. The focus is on two questions: 1) whether dynamics can affect the energy barriers for dislocation emission and cleavage, and 2) what happens in the dynamic "overloaded" situation, in which both processes are energetically possible. In either case, dynamics may shift the balance between brittle cleavage and ductile blunting, thereby affecting the intrinsic ductility of the material. To explore these effects in simulation, a novel interatomic potential is used for which the intrinsic ductility is tunable, and a novel simulation technique is employed, termed a "dynamic cleavage test," in which cracks can be run dynamically at a prescribed energy release rate into a material. Both theory and simulation reveal, however, that the intrinsic ductility of a material is unaffected by dynamics. The energy barrier to dislocation emission appears to be identical in quasi-static and dynamic conditions, and, in the overloaded situation, dislocation emission is kinetically preferred. Thus, dynamics cannot embrittle a ductile material, and the origin of brittle failure in certain alloys (e.g., mild steels) appears to be unrelated to dynamic effects at the crack tip.

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Section: Dynamic Cleavage In 2dmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Crack tip blunting and cleavage under dynamic conditions

Rajan

2016

Journal of the Mechanics and Physics of Solids

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“…Moreover, the branching angle computed with MD (see Zhou et al 1996) is greater than 90°, whereas experiments show much smaller crack branching angles (Ramulu and Kobayashi 1985). One may ask whether quantum mechanical calculations are needed to predict the phenomenon of dynamic fracture in brittle materials (see Cox et al 2005) which is one of the great challenges in dynamic fracture. One likely reason for MD simulations' failure to correctly predict dynamic fracture is that, for example, crack branching events are controlled by the interaction and wave reflections from the boundaries (Ravi-Chandar 1998).…”

Section: Literature Review Of Dynamic Crack Propagationmentioning

confidence: 99%

Studies of dynamic crack propagation and crack branching with peridynamics

Ha¹,

Bobaru²

2010

IUTAM Symposium on Dynamic Fracture and Fragmentation

129

218

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In this paper we discuss the peridynamic analysis of dynamic crack branching in brittle materials and show results of convergence studies under uniform grid refinement (m-convergence) and under decreasing the peridynamic horizon (δ-convergence). Comparisons with experimentally obtained values are made for the crack-tip propagation speed with three different peridynamic horizons. We also analyze the influence of the particular shape of the micro-modulus function and of different materials (Duran 50 glass and soda-lime glass) on the crack propagation behavior. We show that the peridynamic solution for this problem captures all the main features, observed experimentally, of dynamic crack propagation and branching, as well as it obtains crack propagation speeds that compare well, qualitatively and quantitatively, with experimental results published in the literature. The branching patterns also correlate remarkably well with tests published in the literature that show several branching levels at higher stress levels reached when the initial notch starts propagating. We notice the strong influence reflecting stress waves from the boundaries have on the shape and structure of the crack paths in dynamic fracture. All these computational solutions are obtained by using the minimum amount of input information: density, elastic stiffness, and constant fracture energy. No special criteria for crack propagation, crack curving, or crack branching are used: dynamic crack propagation is obtained here as part of the solution. We conclude that peridynamics is a reliable formulation for modeling dynamic crack propagation.

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“…However, this is clearly insufficient to estimate the integrity and residual bearing capacity of concrete structures where cracking usually spreads over an area much bigger than the crater. Thus, simulating crack initiation, development and branching is essential for a proper representation of dynamic damage development in concrete [1].…”

Section: Introductionmentioning

confidence: 99%

Simulation of dynamic behavior of quasi-brittle materials with new rate dependent damage model

Pereira

Weerheijm²,

Sluijs³

2016

Proceedings of the 9th International Conference on Fracture Mechanics of Concrete and Concrete Structures

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Abstract. In concrete often complex fracture and fragmentation patterns develop when subjected to high straining loads. The proper simulation of the dynamic cracking process in concrete is crucial for good predictions of the residual bearing capacity of structures in the risk of being exposed to extraordinary events like explosions, high velocity impacts or earthquakes.As it is well known, concrete is a highly rate dependent material. Experimental and numerical studies indicate that the evolution of damage is governed by complex phenomena taking place simultaneously at different material scales, i.e. micro, meso and macro-scales. Therefore, the constitutive law, and its rate dependency, must be adjusted to the level of representation. For a proper phenomenological (macroscopic) representation of the reality, the constitutive law has to explicitly describe all phenomena taking place at the lower material scales. Macro-scale inertia effects are implicitly simulated by the equation of motion.In the current paper, dynamic crack propagation and branching is studied with a new rate-dependent stress-based nonlocal damage model. The definition of rate in the constitutive law is changed to account for the inherent meso-scale structural inertia effects. This is accomplished by a new concept of effective rate which governs the dynamic delayed response of the material to variations of the deformation (strain) rate, usually described as micro-inertia effects. The proposed model realistically simulates dynamic crack propagation and crack branching phenomena in concrete.

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Modern topics and challenges in dynamic fracture

Cited by 113 publications

References 162 publications

Crack tip blunting and cleavage under dynamic conditions

Crack tip blunting and cleavage under dynamic conditions

Studies of dynamic crack propagation and crack branching with peridynamics

Simulation of dynamic behavior of quasi-brittle materials with new rate dependent damage model

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