Topic
Crack closure
About: Crack closure is a research topic. Over the lifetime, 28157 publications have been published within this topic receiving 588158 citations.
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TL;DR: In this paper, a model of crack growth in an elastic-plastic solid is studied by a computational model, in which a cohesive zone model is used to characterize the fracture process and an effect of plastic straining, reducing the peak stress for separation, is incorporated.
198 citations
TL;DR: In this paper, a method is described to study subcritical crack growth in ceramic materials and large macroscopic size cracks were used and quantitative crack velocity measurements were made on glass and sapphire as a function of applied force, temperature and environment.
Abstract: A method is described to study subcritical crack growth in ceramic materials. Large, macroscopic size cracks were used and quantitative crack velocity measurements were made on glass and sapphire as a function of applied force, temperature and environment. The measured crack velocity was a complex function of stress and water vapor concentration in the environment and portions of the data could be adequately explained by the stress corrosion theory of Charles and Hillig.
198 citations
TL;DR: In this paper, the first measurements of self-healing polymers with embedded shape-memory alloy (SMA) wires were reported, which showed improvements of healed peak fracture loads by up to a factor of 1.6, approaching the performance of the virgin material.
Abstract: We report the first measurements of self-healing polymers with embedded shape-memory alloy (SMA) wires. The addition of SMA wires shows improvements of healed peak fracture loads by up to a factor of 1.6, approaching the performance of the virgin material. Moreover, the repairs can be achieved with reduced amounts of healing agent. The improvements in performance are due to two main effects: (i) crack closure, which reduces the total crack volume and increases the crack fill factor for a given amount of healing agent and (ii) heating of the healing agent during polymerization, which increases the degree of cure of the polymerized healing agent.
198 citations
TL;DR: In this article, the authors extended the cohesive crack model to mixed mode propagation and an experimental confirmation is provided by testing four-point shear specimens of concrete, where a constant crack mouth sliding displacement rate is imposed, so that is is possible to control and detect the snapback load vs deflection branches.
197 citations
25 Nov 2004-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, a convergent lens is used to deliver 1.2-J, 8-ns laser pulses by a Q-switch Nd:YAG laser, operating at 10-Hz.
Abstract: Laser shock processing (LSP) or laser shock peening is a new technique for strengthening metals. This process induces a compressive residual stress field which increases fatigue crack initiation life and reduces fatigue crack growth rate. Specimens of 6061-T6 aluminum alloy are used in this investigation. A convergent lens is used to deliver 1.2 J, 8 ns laser pulses by a Q-switch Nd:YAG laser, operating at 10 Hz. The pulses are focused to a diameter of 1.5 mm onto a water-immersed type aluminum samples. Effect of pulse density in the residual stress field is evaluated. Residual stress distribution as a function of depth is assessed by the hole drilling method. It is observed that the higher the pulse density the larger the zone size with compressive residual stress. Densities of 900, 1350 and 2500 pulses/cm 2 with infrared (1064 nm) radiation are used. Pre-cracked compact tension specimens were subjected to LSP process and then tested under cyclic loading with R = 0.1. Fatigue crack growth rate is determined and the effect of LSP process parameters is evaluated. Fatigue crack growth rate is compared in specimens with and without LSP process. In addition fracture toughness is determined in specimens with and without LSP treatment. It is observed that LSP reduces fatigue crack growth and increases fracture toughness in the 6061-T6 aluminum alloy.
197 citations