The Experts below are selected from a list of 132 Experts worldwide ranked by ideXlab platform
Chaoshui Xu - One of the best experts on this subject based on the ideXlab platform.
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on the Critical Failure Mode transition depth for rock cutting with different back rake angles
Tunnelling and Underground Space Technology, 2017Co-Authors: Xianqun He, Chaoshui Xu, Kang Peng, Gun HuangAbstract:Abstract The Failure Mode of rock under cutting exhibits a ductile-brittle transition as the depth of cut increases. The Critical transition depth, beyond which energy consumed in brittle fracturing surpasses the energy consumed in plastic flow, is the key to differentiating between the ductile and brittle cutting Modes and therefore is an important parameter to optimise tool design and operational parameters to meet specific application requirements. This Critical Failure Mode transition depth depends not only on rock properties but also on cutting operational parameters, in particular, the back rake angle. In this work, a series of rock cutting tests were performed to investigate the influence of back rake angle on the Critical Failure Mode transition depth. Size effect law is employed first to identify the Critical transition depths, which are then compared with values derived from the analysis of specific cutting energy. It is found that the Critical Failure Mode transition depth increases with the back rake angle. This suggests that the brittle fracture Failure induced at large depth of cut can be inhibited by increasing the back rake angle. Cutting at a small back rake angle, on the other hand, is desirable if minimisation of the cutting energy is required in the application.
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Specific Energy as an Index to Identify the Critical Failure Mode Transition Depth in Rock Cutting
Rock Mechanics and Rock Engineering, 2016Co-Authors: Xianqun He, Chaoshui XuAbstract:Rock cutting typically involves driving a rigid cutter across the rock surface at certain depth of cut and is used to remove rock material in various engineering applications. It has been established that there exist two distinct Failure Modes in rock cutting, i.e. ductile Mode and brittle Mode. The ductile Mode takes precedence when the cut is shallow and the increase in the depth of cut leads to rock Failure gradually shifted to brittle-dominant Mode. The threshold depth or the Critical transition depth, at which rock Failure under cutting changes from the ductile to the brittle Mode, is associated with not only the rock properties but also the cutting operational parameters and the understanding of this threshold is important to optimise the tool design and operational parameters. In this study, a new method termed the specific cutting energy transition Model is proposed from an energy perspective which is demonstrated to be much more effective in identifying the Critical transition depth compared with existing approaches. In the ductile Failure cutting Mode, the specific cutting energy is found to be independent of the depth of cut; but in the brittle Failure cutting Mode, the specific cutting energy is found to be dependent on the depth of cut following a power-law relationship. The Critical transition depth is identified as the intersection point between these two relationships. Experimental tests on two types of rocks with different combinations of cutting velocity, depth of cut and back rake angle are conducted and the application of the proposed Model on these cutting datasets has demonstrated that the Model can provide a very effective tool to analyse the cutting mechanism and to identify the Critical transition depth.
Xianqun He - One of the best experts on this subject based on the ideXlab platform.
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on the Critical Failure Mode transition depth for rock cutting with different back rake angles
Tunnelling and Underground Space Technology, 2017Co-Authors: Xianqun He, Chaoshui Xu, Kang Peng, Gun HuangAbstract:Abstract The Failure Mode of rock under cutting exhibits a ductile-brittle transition as the depth of cut increases. The Critical transition depth, beyond which energy consumed in brittle fracturing surpasses the energy consumed in plastic flow, is the key to differentiating between the ductile and brittle cutting Modes and therefore is an important parameter to optimise tool design and operational parameters to meet specific application requirements. This Critical Failure Mode transition depth depends not only on rock properties but also on cutting operational parameters, in particular, the back rake angle. In this work, a series of rock cutting tests were performed to investigate the influence of back rake angle on the Critical Failure Mode transition depth. Size effect law is employed first to identify the Critical transition depths, which are then compared with values derived from the analysis of specific cutting energy. It is found that the Critical Failure Mode transition depth increases with the back rake angle. This suggests that the brittle fracture Failure induced at large depth of cut can be inhibited by increasing the back rake angle. Cutting at a small back rake angle, on the other hand, is desirable if minimisation of the cutting energy is required in the application.
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Specific Energy as an Index to Identify the Critical Failure Mode Transition Depth in Rock Cutting
Rock Mechanics and Rock Engineering, 2016Co-Authors: Xianqun He, Chaoshui XuAbstract:Rock cutting typically involves driving a rigid cutter across the rock surface at certain depth of cut and is used to remove rock material in various engineering applications. It has been established that there exist two distinct Failure Modes in rock cutting, i.e. ductile Mode and brittle Mode. The ductile Mode takes precedence when the cut is shallow and the increase in the depth of cut leads to rock Failure gradually shifted to brittle-dominant Mode. The threshold depth or the Critical transition depth, at which rock Failure under cutting changes from the ductile to the brittle Mode, is associated with not only the rock properties but also the cutting operational parameters and the understanding of this threshold is important to optimise the tool design and operational parameters. In this study, a new method termed the specific cutting energy transition Model is proposed from an energy perspective which is demonstrated to be much more effective in identifying the Critical transition depth compared with existing approaches. In the ductile Failure cutting Mode, the specific cutting energy is found to be independent of the depth of cut; but in the brittle Failure cutting Mode, the specific cutting energy is found to be dependent on the depth of cut following a power-law relationship. The Critical transition depth is identified as the intersection point between these two relationships. Experimental tests on two types of rocks with different combinations of cutting velocity, depth of cut and back rake angle are conducted and the application of the proposed Model on these cutting datasets has demonstrated that the Model can provide a very effective tool to analyse the cutting mechanism and to identify the Critical transition depth.
Yaneng Zhou - One of the best experts on this subject based on the ideXlab platform.
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on the Critical Failure Mode transition depth for rock cutting
International Journal of Rock Mechanics and Mining Sciences, 2013Co-Authors: Yaneng ZhouAbstract:Abstract It has been established that, in rock cutting as well as in indentation, there exist two Failure Modes. In the case of rock cutting, when the depth of cut is shallow the rock fails in ductile Mode, and as the depth of cut increases the Failure shifts to brittle Mode. The Critical depth, at which the Failure Mode transition sharpens, is proportional to some material characteristic length. This study explored the means by which this Critical transition depth could be obtained. Considering the depth of cut as a measure of size and treating rock cutting to be similar in geometry, this study first demonstrated that Bažant's simple size effect equation for quasibrittle material fit rock-cutting data very well. This led to a further exploration of a characteristic length measure that has been widely used in concrete fracture research. With the aid of finite element analysis and few test data points, the Critical depth was expressed in terms of the rock characteristic length. Aided by empirical relationships, the Critical depth was also shown to be a function of rock uniaxial compressive strength.
Gun Huang - One of the best experts on this subject based on the ideXlab platform.
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on the Critical Failure Mode transition depth for rock cutting with different back rake angles
Tunnelling and Underground Space Technology, 2017Co-Authors: Xianqun He, Chaoshui Xu, Kang Peng, Gun HuangAbstract:Abstract The Failure Mode of rock under cutting exhibits a ductile-brittle transition as the depth of cut increases. The Critical transition depth, beyond which energy consumed in brittle fracturing surpasses the energy consumed in plastic flow, is the key to differentiating between the ductile and brittle cutting Modes and therefore is an important parameter to optimise tool design and operational parameters to meet specific application requirements. This Critical Failure Mode transition depth depends not only on rock properties but also on cutting operational parameters, in particular, the back rake angle. In this work, a series of rock cutting tests were performed to investigate the influence of back rake angle on the Critical Failure Mode transition depth. Size effect law is employed first to identify the Critical transition depths, which are then compared with values derived from the analysis of specific cutting energy. It is found that the Critical Failure Mode transition depth increases with the back rake angle. This suggests that the brittle fracture Failure induced at large depth of cut can be inhibited by increasing the back rake angle. Cutting at a small back rake angle, on the other hand, is desirable if minimisation of the cutting energy is required in the application.
David W Alldridge - One of the best experts on this subject based on the ideXlab platform.
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Critical Failure Mode analysis of the petite amateur navy satellite pansat
1995Co-Authors: David W AlldridgeAbstract:Abstract : System reliability analysis is an essential element is the design process. A reliability study should proceed from system inception through final deployment. As the PANSAT project approaches the final design stage and begins initial flight production, the absence of any significant reliability analysis becomes increasingly troubling. This thesis initiates the program's reliability analysis obligation by investigating spacecraft Failure Modes. Typically referenced as Critical Failure Modes, these events will cause complete and permanent system Failure. A reliability analysis tool, called Fault Tree Analysis (FTA), is used to conduct a systematic review of current hardware design architecture to expose potential Critical Failure points or weak links. The analytical result is a Boolean logic tree that describes Critical Failure events and all the potential causes. This causal output relationship describes each component Failure (i.e., single point Failures), or component Failure combinations (i.e., multi-point Failures), which could cause the undesirable Failure event, or Top Event. The fault tree will provide design engineers and management personnel with an effective tool and reference point from which to implement design modifications to circumvent potential problems.