The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform
D Chakraborty - One of the best experts on this subject based on the ideXlab platform.
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Fracture Toughness of structural ceramics
Ceramics International, 1999Co-Authors: Anoop Kumar Mukhopadhyay, S. K. Datta, D ChakrabortyAbstract:Abstract A comparative study of Fracture Toughness evaluation at room temperature of three different structural ceramics viz. sintered alumina, silicon carbide and silicon nitride is reported. Four methods of Fracture Toughness evaluation such as the single edge notched beam (SENB) technique, chevron notched beam (CNB) technique, indentation Fracture (IF) technique and fractographic methods (FM) were compared. In addition, for a given method, the influence of several experimental parameters, e.g. blade width, notch tip radius, normalised notch length and the loading rate on the measured value of Fracture Toughness was investigated in the cases of the aforesaid materials.
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Fracture Toughness of structural ceramics
Ceramics International, 1999Co-Authors: Anoop Kumar Mukhopadhyay, S. K. Datta, D ChakrabortyAbstract:Abstract A comparative study of Fracture Toughness evaluation at room temperature of three different structural ceramics viz. sintered alumina, silicon carbide and silicon nitride is reported. Four methods of Fracture Toughness evaluation such as the single edge notched beam (SENB) technique, chevron notched beam (CNB) technique, indentation Fracture (IF) technique and fractographic methods (FM) were compared. In addition, for a given method, the influence of several experimental parameters, e.g. blade width, notch tip radius, normalised notch length and the loading rate on the measured value of Fracture Toughness was investigated in the cases of the aforesaid materials.
Tomasz Sadowski - One of the best experts on this subject based on the ideXlab platform.
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Refinements on Fracture Toughness of PUR foams
Engineering Fracture Mechanics, 2014Co-Authors: Liviu Marsavina, Emanoil Linul, Dan Mihai Constantinescu, Dragos-alexandru Apostol, Tudor Voiconi, Tomasz SadowskiAbstract:Many efforts have been made in recent years to determine the Fracture Toughness of different types of foams in static and dynamic loading conditions. Taking into account that there is no standard method for the experimental determination of the Fracture Toughness of plastic foams different procedures and specimens were used. This paper presents the polyurethane foam Fracture Toughness results obtained for different foam densities. Two types of specimens were used for determining Fracture Toughness in modes I, II and a mixed one, and also the size effect, loading speed and loading direction were investigated. The paper proposed correlations for density, cell orientation and mixed mode loading based on the experimental testing results.
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On Fracture Toughness of polyurethane foams
2013Co-Authors: Liviu Marsavina, Tomasz Sadowski, Emanoil Linul, Dan Mihai Constantinescu, Marcin Kneć, Dragos-alexandru ApostolAbstract:Polyurethane (PUR) foam materials are widely used as cores in sandwich composites, for packing and cushioning. They are made of interconnected networks of solid struts and cell walls incorporating voids with entrapped gas, Fig. 1. Of particular interest is the Fracture Toughness of such foams because foam failure weakens the structure's capacity for carrying loads. Many efforts have been made in recent years to determine the Fracture Toughness of different types of foams in static and dynamic loading conditions. Micromechanical models and experimental investigations were used for estimating the Fracture Toughness. This paper presents the polyurethane foam Fracture Toughness results obtained for different foam densities. Single edge notch bend specimens were tested at room temperature and with different loading speeds. Our results are presented together with other experimental results and correlations related to micromechanical models are made. Introduction The main characteristics of PUR foams are lightweight, high porosity and good energy absorption capacity, [1]. Foam materials crush in compression, while in tension they fail by propagation of a single crack, [2]. Most of the rigid polymer foams have a linear – elastic behaviour in tension up to Fracture, with a brittle type of failure. So, they can be treated using the Fracture concepts of Linear Elastic Fracture Mechanics (LEFM). Many attempts were carried on in order to predict the Fracture Toughness of foam materials using analytical – micromechanical models [1,3,4,5,6,7,8]. On the other hand, Fracture Toughness tests were performed to find the Fracture Toughness of cellular materials. The first correlation between Fracture Toughness of PUR foams and density (< 200 kg/m 3 ) was proposed by McIntyre and Anderson [9] in a linear form. The same behaviour was observed by Danielsson [10] on PVC Divinycell foams and Viana and Carlsson on Diab H foams [11]. Brittle Fracture without yielding produced in Mode I was observed in experiments. A correlation between the static Fracture Toughness and relative density */s was proposed in [1]. Kabir et al. [12] used the procedure described by ASTM D5045 [13] for determining the Fracture Toughness of polyvinyl chloride (PVC) and polyurethane (PUR) foams. They investigated the effect of density, effect of specimen size, effect of loading rate and effect of cell orientation. Density has a significant effect on Fracture Toughness, which increases more than 7 times when the foam density increases 3.5 times. Burman [14] presented Fracture Toughness results for two commercial foams Rohacell WF51 (density 52 kg/m 3 ) and Divinycell H100 (density 100 kg/m 3 ). The mode I Fracture Toughness KIc was obtained on SENB specimens and has values 0.08 MPa m 0.5 for WF51, respectively 0.21 MPa m 0.5 for H100. He also determined the Mode II Fracture Toughness using End-Notch Flexure (ENF) specimen with values of 0.13 MPa m 0.5 for WF51, respectively 0.21 MPa m 0.5 for H100. This paper presents the experimental results for the Fracture Toughness of PUR foams and comparison with the main micromechanical models from literature. Micromechanical models for prediction of Fracture Toughness of cellular materials Micromechanical analysis allows predicting the mechanical properties of cellular materials based on cell structures. Extensive studies of micromechanical models for cellular materials are presented by Gibson and Ashby [1], Marsavina [2], Mills [3]. Here only the main formulations relating to prediction of Fracture mechanics for plastic foams will be presented. Micromechanical models relate the Fracture Toughness of the foam KIc to the tensile strength of the cell walls fs, cell dimension l and the relative density s. Gibson and Ashby [1] assumed that the crack tip is located at half-edge length and considered an elastic mode I stress field at the crack tip. They start from the stress singularity at the tip of a crack of length 2a and normal to remote loading in an elastic continuum solid, at distance r (on a direction = 0) from crack tip. They considered only the singular term in the Irwin’s stress field solution, and the bending of struts. The proposed relation is:
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Dynamic Fracture Toughness of polyurethane foam
Polymer Testing, 2008Co-Authors: Liviu Marsavina, Tomasz SadowskiAbstract:This paper is a first attempt to determine the dynamic Fracture Toughness of polyurethane foam and to study the effect of impregnation on the Fracture Toughness. Instrumented impact tests were performed using notched specimens. In order to study the effect of impregnation on the impact properties two different resins were used. The obtained results show that the impregnation increases the dynamic Fracture Toughness by 27%.
Srivastava A. - One of the best experts on this subject based on the ideXlab platform.
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High Fracture Toughness micro-architectured materials
'Elsevier BV', 2022Co-Authors: Liu Y., St-pierre L., Fleck N. A., Deshpande V. S., Srivastava A.Abstract:We investigate the possibility of achieving high Fracture Toughness and high strength by the design of lightweight (density below water) metallic micro-architectured materials. The micro-architectured materials were manufactured by drilling a hexagonal array of holes in plates of an aluminum alloy, and the Fracture Toughness was evaluated via three-point bend tests of single-edge notch specimens. The results show that the Fracture Toughness of micro-architectured materials increases with increasing relative density and remarkably, a micro-architectured material can be 50% lighter than the parent material but maintain the same Fracture Toughness. Additional tests on geometrically similar specimens revealed that the Fracture Toughness increases linearly with the square-root of the cell size. The experiments are complemented by finite element calculations of ductile Fracture. In the calculations, the Fracture Toughness of single-edge notch specimens subjected to three-point bending are evaluated using both, a procedure similar to the experiments and direct computation of the J-contour integral. The Fracture Toughness as calculated by both methods are consistent with the experimental results. In addition, the calculations are also carried out for single-edge notch specimens subjected to tensile loading, confirming the validity of the measured Fracture Toughness as a useful material property independent of specimen geometry.Peer reviewe
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High Fracture Toughness micro-architectured materials
'Elsevier BV', 2020Co-Authors: Liu Y., St-pierre L., Na Fleck, Vs Deshpande, Srivastava A.Abstract:© 2020 We investigate the possibility of achieving high Fracture Toughness and high strength by the design of lightweight (density below water) metallic micro-architectured materials. The micro-architectured materials were manufactured by drilling a hexagonal array of holes in plates of an aluminum alloy, and the Fracture Toughness was evaluated via three-point bend tests of single-edge notch specimens. The results show that the Fracture Toughness of micro-architectured materials increases with increasing relative density and remarkably, a micro-architectured material can be 50% lighter than the parent material but maintain the same Fracture Toughness. Additional tests on geometrically similar specimens revealed that the Fracture Toughness increases linearly with the square-root of the cell size. The experiments are complemented by finite element calculations of ductile Fracture. In the calculations, the Fracture Toughness of single-edge notch specimens subjected to three-point bending are evaluated using both, a procedure similar to the experiments and direct computation of the J-contour integral. The Fracture Toughness as calculated by both methods are consistent with the experimental results. In addition, the calculations are also carried out for single-edge notch specimens subjected to tensile loading, confirming the validity of the measured Fracture Toughness as a useful material property independent of specimen geometry
Anoop Kumar Mukhopadhyay - One of the best experts on this subject based on the ideXlab platform.
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Fracture Toughness of structural ceramics
Ceramics International, 1999Co-Authors: Anoop Kumar Mukhopadhyay, S. K. Datta, D ChakrabortyAbstract:Abstract A comparative study of Fracture Toughness evaluation at room temperature of three different structural ceramics viz. sintered alumina, silicon carbide and silicon nitride is reported. Four methods of Fracture Toughness evaluation such as the single edge notched beam (SENB) technique, chevron notched beam (CNB) technique, indentation Fracture (IF) technique and fractographic methods (FM) were compared. In addition, for a given method, the influence of several experimental parameters, e.g. blade width, notch tip radius, normalised notch length and the loading rate on the measured value of Fracture Toughness was investigated in the cases of the aforesaid materials.
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Fracture Toughness of structural ceramics
Ceramics International, 1999Co-Authors: Anoop Kumar Mukhopadhyay, S. K. Datta, D ChakrabortyAbstract:Abstract A comparative study of Fracture Toughness evaluation at room temperature of three different structural ceramics viz. sintered alumina, silicon carbide and silicon nitride is reported. Four methods of Fracture Toughness evaluation such as the single edge notched beam (SENB) technique, chevron notched beam (CNB) technique, indentation Fracture (IF) technique and fractographic methods (FM) were compared. In addition, for a given method, the influence of several experimental parameters, e.g. blade width, notch tip radius, normalised notch length and the loading rate on the measured value of Fracture Toughness was investigated in the cases of the aforesaid materials.
Fang Daining - One of the best experts on this subject based on the ideXlab platform.
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Dynamic Fracture Toughness of Piezoelectric Ceramics
Journal of the American Ceramic Society, 2013Co-Authors: Chen Hao-sen, Yu Xia, Guo Ya-zhou, Fang DainingAbstract:Both dynamic and static three-point bending Fracture testings of 32 piezoelectric ceramic samples were performed in four different poling directions. A modified split Hopkinson pressure bar method with a polyvinylidene fluoride (PVDF)-based gauge was utilized for the dynamic experiments. The loading rate greatly influenced the Fracture Toughness in two ways: the dynamic Fracture Toughness values were much higher than those of the static Fracture Toughness, and unlike the static Fracture Toughness, the influence of poling direction on the dynamic Fracture Toughness was not obvious.
