According to the concept of critical plane, a life prediction approach forrandom multiaxial fatigue is presented. First, the critical plane under the multiaxial randomloading is determined based on the concept of the ...According to the concept of critical plane, a life prediction approach forrandom multiaxial fatigue is presented. First, the critical plane under the multiaxial randomloading is determined based on the concept of the weight-averaged maximum shear strain direction.Then the shear and normal strain histories on the determined critical plane are calculated and takenas the subject of multiaxial load simplifying and multiaxial cycle counting. Furthermore, amultiaxial fatigue life prediction model including the parameters resulted from multiaxial cyclecounting is presented and applied to calculating the fatigue damage generated from each cycle.Finally, the cumulative damage is added up using Miner's linear rule, and the fatigue predictionlife is given. The experiments under multiaxial loading blocks are used for the verification of theproposed method. The prediction has a good correction with the experimental results.展开更多
A promising approach on the search for geometric constraint of directionalgraph in off-line parametric design has been put forward. The method for representation of thedirectional graph is given firstly, then the cons...A promising approach on the search for geometric constraint of directionalgraph in off-line parametric design has been put forward. The method for representation of thedirectional graph is given firstly, then the constraint model for every geometry element is putforward. By the search of geometric constraint, it sets up the topology constraint relation on thedifferent element objects, which are not related in geometry data base, and achieves the identifyfor the directional graph. The algorithm of recognizing geometric constraint is described in detail,in the meantime, the application example in off-line parametric design on dimension-driven isgiven.展开更多
Experimental studies on load decay and leak rate of O-rings made of two kindsof silicone rubber are conducted. The results show that the characteristic of load decay isrelative to the material and temperature of O-rin...Experimental studies on load decay and leak rate of O-rings made of two kindsof silicone rubber are conducted. The results show that the characteristic of load decay isrelative to the material and temperature of O-rings; the rate of load decay increases with the riseof temperature; the effects of load decay on leak rate of O-rings are negligible at roomtemperature, but they are notable at high temperature, and they are related to the material ofO-rings. On the basis of study on the theory of load decay and analysis to the results ofexperiments, a theoretical model is developed to describe the load decay characteristic of O-rings,and it matches the experimental data very well. By the study of time-temperature equivalence of loaddecay, the interconvertting equation of test data of load decay at different temperatures isobtained.展开更多
A novel construction algorithm is presented to generate a conforming Voronoi mesh for any planar straight line graph (PSLG). It is also extended to tesselate multiple-intersected PSLGs. All the algorithms are guarante...A novel construction algorithm is presented to generate a conforming Voronoi mesh for any planar straight line graph (PSLG). It is also extended to tesselate multiple-intersected PSLGs. All the algorithms are guaranteed to converge. Examples are given to illustrate its efficiency.展开更多
A new method as a post-processing step is presented to improve the shape quality of triangular meshes, which uses a topological clean up procedure and discrete smoothing interpolate (DSI) algorithm together. T...A new method as a post-processing step is presented to improve the shape quality of triangular meshes, which uses a topological clean up procedure and discrete smoothing interpolate (DSI) algorithm together. This method can improve the angle distribution of mesh element. while keeping the resulting meshes conform to the predefined constraints which are inputted as a PSLG.展开更多
As-cast AM60 magnesium alloy ingot with grains coarser than those of as-extruded AZ series is more liable to produce cracks under ECAD with severe shear strain. A feasible scheme of equal channel angular deformation (...As-cast AM60 magnesium alloy ingot with grains coarser than those of as-extruded AZ series is more liable to produce cracks under ECAD with severe shear strain. A feasible scheme of equal channel angular deformation (ECAD) for as-cast AM60 magnesium alloy ingot was proposed in this paper. The tests were conducted on Instron machine with hydraulic back-force machine. Through analysing load us displacement curves, the effects of ECAD processing conditions on deformability and microstructure of as-cast magnesium AM60 billets were discussed. During testing, the back-force employment was helpful to keep ECAD processing more stable. And with back-force, it was observed that the number of ECAD passes in different routes could tremendously affect the deformability and microstructure of magnesium specimens. It was concluded that ECAD processing is entirely feasible for as-cast magnesium AM60 alloy under severe shear strain, and back-force employment, multi-passes deformation and lubrication of graphite paper are the factors primarily beneficial to improvement of deformability and refinement of grained structure. This work provides a way to produce magnesium alloy with fine-grained structure directly from casting ingot by ECAD technique.展开更多
We develop a neuro-knowledge-based expert system (NKBES) frame in this work. The system mainly concerns with decision of gating system and die casting machine based on a neuro-inference engine launched under the MATLA...We develop a neuro-knowledge-based expert system (NKBES) frame in this work. The system mainly concerns with decision of gating system and die casting machine based on a neuro-inference engine launched under the MATLAB software environment. For enhancement of reasoning agility, an error back-propagation neural network was applied. A rapidly convergent adaptive learning rate (ALR) and a momentum-based error back-propagation algorithm was used to conduct neuro-reasoning. The working effect of the system was compared to a conventional expert system that is based on a two-way (forward and backward) chaining inference mechanism. As the reference, the present paper provided the neural networks sum-squared error (S5E) and ALR vs iterative epoch curves of process planning case mentioned above. The study suggests that the neuro-modeling optimization application to die casting process design has good feasibility, and based on that a novel and effective intelligent expert system can be launched at low cost.展开更多
A multidisciplinary approach to the fabrication of biologically based magnetic monomers for biolimited forming is described. Rod-like Bacilli cereus about 0.5 mm in diameter and 3—5 mm in length, were used as templat...A multidisciplinary approach to the fabrication of biologically based magnetic monomers for biolimited forming is described. Rod-like Bacilli cereus about 0.5 mm in diameter and 3—5 mm in length, were used as templates on which the ferromagnetic material was deposited by an elec-troless deposition method. Different electroless plating solu-tions were compared in detail and CoNiP solution was se-lected. During the deposition process, both dispersant and mechanical stirring were used to solve the problem of ag-gregation of bacterial cells so as to obtain a uniform plating layer. The CoNiP film on Bacilli cereus was a mixture of crystalline and non-crystalline in the phase structure and showed a good magnetism. The magnetic metallized bacte-rial cells could be manipulated with a magnetic field. Parallel arrays of these micro magnetic particles were achieved and they could rotate along with the magnetic field.展开更多
基金This project is supported by National Natural Science Foundation of China (No.59775030).
文摘According to the concept of critical plane, a life prediction approach forrandom multiaxial fatigue is presented. First, the critical plane under the multiaxial randomloading is determined based on the concept of the weight-averaged maximum shear strain direction.Then the shear and normal strain histories on the determined critical plane are calculated and takenas the subject of multiaxial load simplifying and multiaxial cycle counting. Furthermore, amultiaxial fatigue life prediction model including the parameters resulted from multiaxial cyclecounting is presented and applied to calculating the fatigue damage generated from each cycle.Finally, the cumulative damage is added up using Miner's linear rule, and the fatigue predictionlife is given. The experiments under multiaxial loading blocks are used for the verification of theproposed method. The prediction has a good correction with the experimental results.
基金This project is supported by National 863/C1MS Plan(No.863-511-507) Provincial Natural Science Foundation of Anhui, China (No.01042209).
文摘A promising approach on the search for geometric constraint of directionalgraph in off-line parametric design has been put forward. The method for representation of thedirectional graph is given firstly, then the constraint model for every geometry element is putforward. By the search of geometric constraint, it sets up the topology constraint relation on thedifferent element objects, which are not related in geometry data base, and achieves the identifyfor the directional graph. The algorithm of recognizing geometric constraint is described in detail,in the meantime, the application example in off-line parametric design on dimension-driven isgiven.
基金This project is supported by 863 Program of China (No. 863-2-4-4-7).
文摘Experimental studies on load decay and leak rate of O-rings made of two kindsof silicone rubber are conducted. The results show that the characteristic of load decay isrelative to the material and temperature of O-rings; the rate of load decay increases with the riseof temperature; the effects of load decay on leak rate of O-rings are negligible at roomtemperature, but they are notable at high temperature, and they are related to the material ofO-rings. On the basis of study on the theory of load decay and analysis to the results ofexperiments, a theoretical model is developed to describe the load decay characteristic of O-rings,and it matches the experimental data very well. By the study of time-temperature equivalence of loaddecay, the interconvertting equation of test data of load decay at different temperatures isobtained.
基金Supported by the Science Technology Development Program of Beijing Municipal Education Commission (KM200510011004)
文摘A novel construction algorithm is presented to generate a conforming Voronoi mesh for any planar straight line graph (PSLG). It is also extended to tesselate multiple-intersected PSLGs. All the algorithms are guaranteed to converge. Examples are given to illustrate its efficiency.
文摘A new method as a post-processing step is presented to improve the shape quality of triangular meshes, which uses a topological clean up procedure and discrete smoothing interpolate (DSI) algorithm together. This method can improve the angle distribution of mesh element. while keeping the resulting meshes conform to the predefined constraints which are inputted as a PSLG.
基金This work was supported,in part,by the China Scholarship Council under grant number 21852035in part,was supported by the Australia Research Council.
文摘As-cast AM60 magnesium alloy ingot with grains coarser than those of as-extruded AZ series is more liable to produce cracks under ECAD with severe shear strain. A feasible scheme of equal channel angular deformation (ECAD) for as-cast AM60 magnesium alloy ingot was proposed in this paper. The tests were conducted on Instron machine with hydraulic back-force machine. Through analysing load us displacement curves, the effects of ECAD processing conditions on deformability and microstructure of as-cast magnesium AM60 billets were discussed. During testing, the back-force employment was helpful to keep ECAD processing more stable. And with back-force, it was observed that the number of ECAD passes in different routes could tremendously affect the deformability and microstructure of magnesium specimens. It was concluded that ECAD processing is entirely feasible for as-cast magnesium AM60 alloy under severe shear strain, and back-force employment, multi-passes deformation and lubrication of graphite paper are the factors primarily beneficial to improvement of deformability and refinement of grained structure. This work provides a way to produce magnesium alloy with fine-grained structure directly from casting ingot by ECAD technique.
文摘We develop a neuro-knowledge-based expert system (NKBES) frame in this work. The system mainly concerns with decision of gating system and die casting machine based on a neuro-inference engine launched under the MATLAB software environment. For enhancement of reasoning agility, an error back-propagation neural network was applied. A rapidly convergent adaptive learning rate (ALR) and a momentum-based error back-propagation algorithm was used to conduct neuro-reasoning. The working effect of the system was compared to a conventional expert system that is based on a two-way (forward and backward) chaining inference mechanism. As the reference, the present paper provided the neural networks sum-squared error (S5E) and ALR vs iterative epoch curves of process planning case mentioned above. The study suggests that the neuro-modeling optimization application to die casting process design has good feasibility, and based on that a novel and effective intelligent expert system can be launched at low cost.
基金This work was supported by the National Hi-Techno-logy Research and Development Program of China (Grant No. 2001AA421120) and the National Natural Science Foundation of China (Grant No. 59975007).
文摘A multidisciplinary approach to the fabrication of biologically based magnetic monomers for biolimited forming is described. Rod-like Bacilli cereus about 0.5 mm in diameter and 3—5 mm in length, were used as templates on which the ferromagnetic material was deposited by an elec-troless deposition method. Different electroless plating solu-tions were compared in detail and CoNiP solution was se-lected. During the deposition process, both dispersant and mechanical stirring were used to solve the problem of ag-gregation of bacterial cells so as to obtain a uniform plating layer. The CoNiP film on Bacilli cereus was a mixture of crystalline and non-crystalline in the phase structure and showed a good magnetism. The magnetic metallized bacte-rial cells could be manipulated with a magnetic field. Parallel arrays of these micro magnetic particles were achieved and they could rotate along with the magnetic field.
