髓内钉固定骨折面是治疗髋关节骨折的主要方法,髓内固定系统的力学可靠性是确保治疗成功的关键.针对股骨转子间骨折,构建了计及股骨层状结构特点和肌肉力作用的髓内固定系统有限元模型,模拟分析了缓步行走条件下固定系统的力学响应.为...髓内钉固定骨折面是治疗髋关节骨折的主要方法,髓内固定系统的力学可靠性是确保治疗成功的关键.针对股骨转子间骨折,构建了计及股骨层状结构特点和肌肉力作用的髓内固定系统有限元模型,模拟分析了缓步行走条件下固定系统的力学响应.为定量化评估髓内固定系统的力学可靠性,提出安全因数的概念,并基于这一概念定量化考察了头钉定位参数对固定系统力学可靠性的影响.研究表明,固定系统在股骨与头钉、主钉与头钉,以及主钉与锁钉的接触区存在明显的应力集中,是评估髓内固定系统力学可靠性的关键区域.研究还表明,髓内固定系统具有良好的力学可靠性,降低头钉高度有利于提高髓内固定系统的力学可靠性,而头钉近端钉角(proximal nail angle)对固定系统可靠性的影响可以忽略.展开更多
In order to improve the strength and stiffness of shield cutterhead, the method of fuzzy mathematics theory in combination with the finite element analysis is adopted. An optimal design model of structural parameters ...In order to improve the strength and stiffness of shield cutterhead, the method of fuzzy mathematics theory in combination with the finite element analysis is adopted. An optimal design model of structural parameters for shield cutterhead is formulated,based on the complex engineering technical requirements. In the model, as the objective function of the model is a composite function of the strength and stiffness, the response surface method is applied to formulate the approximate function of objective function in order to reduce the solution scale of optimal problem. A multi-objective genetic algorithm is used to solve the cutterhead structure design problem and the change rule of the stress-strain with various structural parameters as well as their optimal values were researched under specific geological conditions. The results show that compared with original cutterhead structure scheme, the obtained optimal scheme of the cutterhead structure can greatly improve the strength and stiffness of the cutterhead, which can be seen from the reduction of its maximum equivalent stress by 21.2%, that of its maximum deformation by 0.75%, and that of its mass by 1.04%.展开更多
For the safety protection of passengers when train crashes occur, special structures are crucially needed as a kind of indispensable energy absorbing device. With the help of the structures, crash kinetic-energy can b...For the safety protection of passengers when train crashes occur, special structures are crucially needed as a kind of indispensable energy absorbing device. With the help of the structures, crash kinetic-energy can be completely absorbed or dissipated for the aim of safety. Two composite structures(circumscribed circle structure and inscribed circle structure) were constructed. In addition, comparison and optimization of the crashworthy characteristic of the two structures were carried out based on the method of explicit finite element analysis(FEA) and Kriging surrogate model. According to the result of Kriging surrogate model, conclusions can be safely drawn that the specific energy absorption(SEA) and ratio of specific energy absorption to initial peak force(REAF) of circumscribed circle structure are lager than those of inscribed circle structure under the same design parameters. In other words, circumscribed circle structure has better performances with higher energy-absorbing ability and lower initial peak force. Besides, error analysis was adopted and the result of which indicates that the Kriging surrogate model has high nonlinear fitting precision. What is more, the SEA and REAF optimum values of the two structures have been obtained through analysis, and the crushing results have been illustrated when the two structures reach optimum SEA and REAF.展开更多
文摘髓内钉固定骨折面是治疗髋关节骨折的主要方法,髓内固定系统的力学可靠性是确保治疗成功的关键.针对股骨转子间骨折,构建了计及股骨层状结构特点和肌肉力作用的髓内固定系统有限元模型,模拟分析了缓步行走条件下固定系统的力学响应.为定量化评估髓内固定系统的力学可靠性,提出安全因数的概念,并基于这一概念定量化考察了头钉定位参数对固定系统力学可靠性的影响.研究表明,固定系统在股骨与头钉、主钉与头钉,以及主钉与锁钉的接触区存在明显的应力集中,是评估髓内固定系统力学可靠性的关键区域.研究还表明,髓内固定系统具有良好的力学可靠性,降低头钉高度有利于提高髓内固定系统的力学可靠性,而头钉近端钉角(proximal nail angle)对固定系统可靠性的影响可以忽略.
基金Project(51074180) supported by the National Natural Science Foundation of ChinaProject(2012AA041801) supported by the National High Technology Research and Development Program of China+2 种基金Project(2007CB714002) supported by the National Basic Research Program of ChinaProject(2013GK3003) supported by the Technology Support Plan of Hunan Province,ChinaProject(2010FJ1002) supported by Hunan Science and Technology Major Program,China
文摘In order to improve the strength and stiffness of shield cutterhead, the method of fuzzy mathematics theory in combination with the finite element analysis is adopted. An optimal design model of structural parameters for shield cutterhead is formulated,based on the complex engineering technical requirements. In the model, as the objective function of the model is a composite function of the strength and stiffness, the response surface method is applied to formulate the approximate function of objective function in order to reduce the solution scale of optimal problem. A multi-objective genetic algorithm is used to solve the cutterhead structure design problem and the change rule of the stress-strain with various structural parameters as well as their optimal values were researched under specific geological conditions. The results show that compared with original cutterhead structure scheme, the obtained optimal scheme of the cutterhead structure can greatly improve the strength and stiffness of the cutterhead, which can be seen from the reduction of its maximum equivalent stress by 21.2%, that of its maximum deformation by 0.75%, and that of its mass by 1.04%.
基金Projects(51405516,U1334208)supported by the National Natural Science Foundation of ChinaProject(2013GK2001)supported by the Science and Technology Program for Hunan Provincial Science and Technology Department,ChinaProject(2013zzts040)supported by the Graduate Degree Thesis Innovation Foundation of Central South University,China
文摘For the safety protection of passengers when train crashes occur, special structures are crucially needed as a kind of indispensable energy absorbing device. With the help of the structures, crash kinetic-energy can be completely absorbed or dissipated for the aim of safety. Two composite structures(circumscribed circle structure and inscribed circle structure) were constructed. In addition, comparison and optimization of the crashworthy characteristic of the two structures were carried out based on the method of explicit finite element analysis(FEA) and Kriging surrogate model. According to the result of Kriging surrogate model, conclusions can be safely drawn that the specific energy absorption(SEA) and ratio of specific energy absorption to initial peak force(REAF) of circumscribed circle structure are lager than those of inscribed circle structure under the same design parameters. In other words, circumscribed circle structure has better performances with higher energy-absorbing ability and lower initial peak force. Besides, error analysis was adopted and the result of which indicates that the Kriging surrogate model has high nonlinear fitting precision. What is more, the SEA and REAF optimum values of the two structures have been obtained through analysis, and the crushing results have been illustrated when the two structures reach optimum SEA and REAF.
