Papers by Keyword: Damage Zone

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Authors: Xiao Lei Li, Xiao Jing Li, Jian Bing Sang, Yan Hui Qie, Yao Ping Tu, Cheng Bo Zhang
Abstract: Studying the deformation and fracture properties of soft materials can not only provide insight into the physical mechanisms underlying their superior properties and functions but also benefit the design and fabrication of rubberlike materials. In this paper, an application of the experimental digital moire method to determine the damage zone around crack tip for rubberlike material is presented. The measurement principles and the basic procedures of the method are explained in detail. The in-plane defomation distributions of crack tip fields under Mode I fracture condition are measured. In addition, the deformation of crack tip fields in the damage zones is also analyzed using the sector division mode. Finally, an analysis of the damage zone is proposed to describe crack-tip fields in rubber-like materials with large deformation.
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Authors: Xiao Lei Li, Xiao Jing Li, Jian Bing Sang, Yan Hui Qie, Yao Ping Tu, Cheng Bo Zhang
Abstract: Studying the deformation and fracture properties of soft materials can not only provide insight into the physical mechanisms underlying their superior properties and functions but also benefit the design and fabrication of rubberlike materials. In this paper, an application of the experimental digital moire method to determine the damage zone around crack tip for rubberlike material is presented. The measurement principles and the basic procedures of the method are explained in detail. The deformation of crack tip fields in the damage zones is analyzed using the sector division mode. Finally, an analysis of the damage zone is proposed to describe crack-tip fields in rubber-like materials with large deformation.
283
Authors: Mitsugu Todo, Yoshihiro Fukuya, Seiya Hagihara, Kazuo Arakawa
Abstract: Microscopic studies on the toughening mechanism of rubber-toughened PMMA (RTPMMA) were carried out using a polarizing optical microscope (POM) and a transmission electron microscope (TEM). POM result showed that in a typical RT-PMMA, a damage zone was developed in the vicinity of crack-tip, and therefore, it was considered that energy dissipation due to the damage zone development was the primary toughening mechanism. TEM result exhibited that the damage zone was a crowd of micro-crazes generated around rubber particles in the vicinity of notch-tip. Finite element analysis was then performed to simulate such damage formations in crack-tip region. Macro-scale and micro-scale models were developed to simulate damage zone formation and micro-crazing, respectively, with use of a damage model. It was shown that the damage model introduced was successfully applied to predict such kind of macro-damage and micro-craze formations.
1019
Authors: Bustami Syam, Hiroomi Homma, Kohji Nakazato
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Authors: Sang Yeob Oh, Hyung Seop Shin, Chang Min Suh
Abstract: In order to investigate the effect of a confinement condition on the damage induced by a spherical impact, an experimental setup that can impact contact pressure to the specimen through a pressing die was composed. The steel and the WC balls in 3mm diameter impacted to the soda-lime glass specimen with dimension of 33×33×8m in the impact velocity range of 30m/s to 200m/s. Three different conditions are given for the impact damage investigation, which are the case without a pressing die and the cases of p=0MPa and p=200MPa with a pressing die. The stress distribution in the glass specimen by impacting the particle was also evaluated using MARC s/w system. The particle impact produced various kinds of the damage such as the ring and the cone cracks, the radial cracks and the craters. The contact pressure applied to the specimen changed stress fields in the specimen. The damage zones of the specimen without a pressing die increased as the impact velocity increased. The damage extents in the specimen with the contact pressure of 200MPa were reduced as compared with the case of those without a pressing die.
1315
Authors: David Taylor
Abstract: The work described below investigates, for the first time, the link between microstructural parameters such as grain size and the length constant L which is known as the critical distance. L is frequently used in the prediction of failure processes such as brittle fracture and fatigue, initiated at stress concentration features such as notches. Values of L were calculated using data from the literature on the effect of short cracks and notches in steels and ceramics. In some cases, simple relationships could be established between L and the grain size, or other microstructural features. Sometimes L was found to be much larger than anything in the microstructure and appeared to be related to the size of the damage zone at failure.
23
Authors: M. Chabaat, S. Djouder, M. Touati
Abstract: In this study, interaction of a main crack with its surrounding damage, which consists of continuous lines of discontinuities, is analysed. To solve this complex problem, a Semi-Empirical Approach (SEA), which relies on experimentally measured crack opening displacements as the solution to this multiple crack interaction problem is suggested. The solution procedure is illustrated, first, for a particular case of the interaction of an array of horizontal and vertical crazes with a main crack, and second, for the generalized case to include the whole damage of crazing patterns surrounding the main crack. The results show that the crack Damage Zone (DZ) or the socalled Process Zone (PZ) interaction may either amplify or suppress the resulting stress field depending on the crack damage configuration. Green’s function for the Stress Intensity Factor (SIF) is employed to quantify the effects on a crack of the damage of continuous patterns of discontinuities. It follows from the analysis that an increase in the number of crazing patterns will amplify the stress at the main crack. It is also shown throughout this study that the overall effect of the damage is identified, as being an amplifying one and that the resulting local stress field would direct the propagation of the main crack since there is no toughening.
243
Authors: Shirley Savet Lana, Hiroomi Homma, Kohji Nakazato
Abstract: The dynamic fracture tests were carried out for a glass fiber reinforced plastic specimen with a crack and dynamic fracture toughness was evaluated by examination of cracking at an initial slit root. Before the crack initiated at the slit root, a whitened damage zone was created surrounding the slit tip. The damage zone consists of micro cracking in the matrix, debonding between a fiber and the matrix, and fracture of the fiber. The comparison of the dynamic fracture toughness and the static fracture toughness value shows that the former is around 12 MPa√m and apparently higher than the later, which is 7 MPa√m. To understand those experimental results and mechanics of the damage zone, a dynamic debonding test was carried out and dynamic bonding strength was estimated as around 70 MPa.
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