Two parameters,block spectrum intensity Seq and spectrum shape factor a,which describe the characteristics of the loading block spectrum are defined,and the relationship between the parameters and fatigue crack propag...Two parameters,block spectrum intensity Seq and spectrum shape factor a,which describe the characteristics of the loading block spectrum are defined,and the relationship between the parameters and fatigue crack propagation behaviours is investigated.It is shown that the spectrum intensity is an 'average drive force' of fatigue crack propagation,and the variance of fatigue crack size at a given fatigue life is closely related to the spectrum shape factor α.展开更多
A probabilistic method based on principle of maximum entropy was employed to analyze the randomness of contact force between geomembrane and granular material.The contact force distribution is exponential according to...A probabilistic method based on principle of maximum entropy was employed to analyze the randomness of contact force between geomembrane and granular material.The contact force distribution is exponential according to the proposed method and the grain size is the most important factor that affects the distribution of contact force.The proposed method is then verified by a series of laboratory experiments using glass beads and cobbles as granular material and a very thin pressure,indicating that film is firstly used in these experiments which give a reliable method to measure the contact force at each contact point.展开更多
The effects of stochastic characteristics of materials on the reliability of ship hulls made of composite materials under longitudinal moment were extensively studied using reliability and sensitivity calculations of ...The effects of stochastic characteristics of materials on the reliability of ship hulls made of composite materials under longitudinal moment were extensively studied using reliability and sensitivity calculations of a composite ship hull which was sagging.The reliability indices and failure probabilities of the ship in three kinds of failure modes (buckling,material failure,and ultimate collapse) were calculated by the surface response method and JC method.The importance factors of random variables in stochastic models,such as the model errors in predicting the ultimate longitudinal strength of ship and the longitudinal bending moment that the ship withstands,as well as the stochastic characteristics of materials in the models used,were calculated.Then,the effects of these random variables,including the stochastic characteristics of materials on the reliability index and the failure probability of ships which were sagging,were discussed with their importance factors.The results show that the effects of stochastic characteristics of materials on the reliability of ship hulls made of composite materials should be considered during the reliability assessment of composite ships.Finally,some conclusions and recommendations were given for high-speed ship design and safety assessment.展开更多
Unlike nonspecific adhesion of conventional hard materials in engineering commonly described by JKR and DMT type models,the molecular adhesion via specific receptor-ligand bonds is stochastic by nature and has the fea...Unlike nonspecific adhesion of conventional hard materials in engineering commonly described by JKR and DMT type models,the molecular adhesion via specific receptor-ligand bonds is stochastic by nature and has the feature that its strength strongly depends on the medium stiffness surrounding the adhesion.In this paper,we demonstrate in a stochastic-elasticity framework that a type of materials with linearly graded elastic modulus can be designed to achieve "equal load sharing" and enhanced cooperative rebinding among interfacial molecular bonds.Upon modulus gradation,multiple molecular bonds can be elastically decoupled but statistically cooperative.In general,uniform molecular adhesion can be accomplished by two strategies:homogeneous materials with sufficient stiffness higher than a threshold or heterogeneous materials satisfying the criterion on modulus gradation.These results not only provide a theoretical principle for possible applications of functionally graded materials in quantitatively controlling cell-matrix adhesion,but also have general implications on adhesion between soft materials mediated by specific molecular binding.展开更多
文摘Two parameters,block spectrum intensity Seq and spectrum shape factor a,which describe the characteristics of the loading block spectrum are defined,and the relationship between the parameters and fatigue crack propagation behaviours is investigated.It is shown that the spectrum intensity is an 'average drive force' of fatigue crack propagation,and the variance of fatigue crack size at a given fatigue life is closely related to the spectrum shape factor α.
基金Project(51079047)supported by the National Natural Science Foundation of ChinaProject Funded by the Priority Academic Program of Jiangsu Higher Education Institutions,China
文摘A probabilistic method based on principle of maximum entropy was employed to analyze the randomness of contact force between geomembrane and granular material.The contact force distribution is exponential according to the proposed method and the grain size is the most important factor that affects the distribution of contact force.The proposed method is then verified by a series of laboratory experiments using glass beads and cobbles as granular material and a very thin pressure,indicating that film is firstly used in these experiments which give a reliable method to measure the contact force at each contact point.
文摘The effects of stochastic characteristics of materials on the reliability of ship hulls made of composite materials under longitudinal moment were extensively studied using reliability and sensitivity calculations of a composite ship hull which was sagging.The reliability indices and failure probabilities of the ship in three kinds of failure modes (buckling,material failure,and ultimate collapse) were calculated by the surface response method and JC method.The importance factors of random variables in stochastic models,such as the model errors in predicting the ultimate longitudinal strength of ship and the longitudinal bending moment that the ship withstands,as well as the stochastic characteristics of materials in the models used,were calculated.Then,the effects of these random variables,including the stochastic characteristics of materials on the reliability index and the failure probability of ships which were sagging,were discussed with their importance factors.The results show that the effects of stochastic characteristics of materials on the reliability of ship hulls made of composite materials should be considered during the reliability assessment of composite ships.Finally,some conclusions and recommendations were given for high-speed ship design and safety assessment.
基金supported by the Start-up Funding from Young Thousand-Talent Program of Chinathe Fundamental Research Funds for Central Universities (Grant No. 2011XZZX002)the National Natural Science Foundation of China (Grant No. 11072273)
文摘Unlike nonspecific adhesion of conventional hard materials in engineering commonly described by JKR and DMT type models,the molecular adhesion via specific receptor-ligand bonds is stochastic by nature and has the feature that its strength strongly depends on the medium stiffness surrounding the adhesion.In this paper,we demonstrate in a stochastic-elasticity framework that a type of materials with linearly graded elastic modulus can be designed to achieve "equal load sharing" and enhanced cooperative rebinding among interfacial molecular bonds.Upon modulus gradation,multiple molecular bonds can be elastically decoupled but statistically cooperative.In general,uniform molecular adhesion can be accomplished by two strategies:homogeneous materials with sufficient stiffness higher than a threshold or heterogeneous materials satisfying the criterion on modulus gradation.These results not only provide a theoretical principle for possible applications of functionally graded materials in quantitatively controlling cell-matrix adhesion,but also have general implications on adhesion between soft materials mediated by specific molecular binding.
