The deformation characteristic in the forming process of aluminum alloy 7075 cross valve under multi-way loading was investigated by numerical simulation method. The results indicate that there exist 4 deformation pat...The deformation characteristic in the forming process of aluminum alloy 7075 cross valve under multi-way loading was investigated by numerical simulation method. The results indicate that there exist 4 deformation patterns in the multi-way loading forming process of cross valve, such as forward extrusion, backward extrusion, forward-lateral extrusion and backward-lateral extrusion; one or several patterns occur at different forming stages depending on loading path. In general, the main deformation pattern is forward extrusion or backward extrusion at the initial stage; the main deformation pattern is backward extrusion at the intermediate stage, and the backward extrusion and forward-lateral extrusion occur at the final stage. In order to improve the cavity fill and reduce the forming defects, the lateral extrusion deformation should be increased at the initial and intermediate stages, and the forward extrusion deformation at the final forging stage should be reduced or avoided.展开更多
Deformation behavior,temperature evolution and coupled effects have a significant influence on forming process and quality of component formed,which are very complex in forming process of aluminum alloy 7075 cross val...Deformation behavior,temperature evolution and coupled effects have a significant influence on forming process and quality of component formed,which are very complex in forming process of aluminum alloy 7075 cross valve under multi-way loading due to the complexity of loading path and the multiplicity of associated processing parameters.A model of the process was developed under DFEORM-3D environment based on the coupled thermo-mechanical finite element method.The comparison between two process models,the conventional isothermal process model and the non-isothermal process model developed in this study,was carried out,and the results indicate that the thermal events play an important role in the aluminum alloy forming process under multi-way loading.The distributions and evolutions of the temperature field and strain filed are obtained by non-isothermal process simulation.The plastic zone and its extension in forming process of cross valve were analyzed.The results may provide guidelines for the determination of multi-way loading forming scheme and loading conditions of the forming cross valve components.展开更多
A sequential injection analysis (SIA) system based on polydimethylsiloxane (PDMS) chip with integrated pneumatic-actuated valves was developed. A novel SIA operation mode using multiphase laminar flow effect and pneum...A sequential injection analysis (SIA) system based on polydimethylsiloxane (PDMS) chip with integrated pneumatic-actuated valves was developed. A novel SIA operation mode using multiphase laminar flow effect and pneumatic microvalve control was proposed. The sample and reagent solutions were synchronously loaded and injected in the chip-based sample injection module instead of multi-step sequential injection by a multiposition valve and a reciprocating pump as in conventional SIA system. The sample and reagent injection volumes were reduced to ca. 1.1 nL. The present system has the advantages of simple structure, fast and convenient operation, low sample and reagent consumption, and high degree of integration and automation. The system operation conditions were optimized using fluorescein as model sample. Its feasibility in biological analysis was preliminarily demonstrated in enzyme inhibition assay.展开更多
基金Project(2011ZX04016-081)supported by the National Science and Technology Major Project of China
文摘The deformation characteristic in the forming process of aluminum alloy 7075 cross valve under multi-way loading was investigated by numerical simulation method. The results indicate that there exist 4 deformation patterns in the multi-way loading forming process of cross valve, such as forward extrusion, backward extrusion, forward-lateral extrusion and backward-lateral extrusion; one or several patterns occur at different forming stages depending on loading path. In general, the main deformation pattern is forward extrusion or backward extrusion at the initial stage; the main deformation pattern is backward extrusion at the intermediate stage, and the backward extrusion and forward-lateral extrusion occur at the final stage. In order to improve the cavity fill and reduce the forming defects, the lateral extrusion deformation should be increased at the initial and intermediate stages, and the forward extrusion deformation at the final forging stage should be reduced or avoided.
基金Project(50735005) supported by the National Natural Science Foundation for Key Program of ChinaProject(2006AA04Z135) supported by the National High-tech Research and Development Program of China+1 种基金Project supported by the Foundational Research Program of National Defence, ChinaProject supported by Northwestern Polytechnical University Foundation for Fundamental Research, China
文摘Deformation behavior,temperature evolution and coupled effects have a significant influence on forming process and quality of component formed,which are very complex in forming process of aluminum alloy 7075 cross valve under multi-way loading due to the complexity of loading path and the multiplicity of associated processing parameters.A model of the process was developed under DFEORM-3D environment based on the coupled thermo-mechanical finite element method.The comparison between two process models,the conventional isothermal process model and the non-isothermal process model developed in this study,was carried out,and the results indicate that the thermal events play an important role in the aluminum alloy forming process under multi-way loading.The distributions and evolutions of the temperature field and strain filed are obtained by non-isothermal process simulation.The plastic zone and its extension in forming process of cross valve were analyzed.The results may provide guidelines for the determination of multi-way loading forming scheme and loading conditions of the forming cross valve components.
基金supported by the National Natural Science Foundation of China (20825517, 20890020)Ministry of Science and Technology of China (2007CB714503)
文摘A sequential injection analysis (SIA) system based on polydimethylsiloxane (PDMS) chip with integrated pneumatic-actuated valves was developed. A novel SIA operation mode using multiphase laminar flow effect and pneumatic microvalve control was proposed. The sample and reagent solutions were synchronously loaded and injected in the chip-based sample injection module instead of multi-step sequential injection by a multiposition valve and a reciprocating pump as in conventional SIA system. The sample and reagent injection volumes were reduced to ca. 1.1 nL. The present system has the advantages of simple structure, fast and convenient operation, low sample and reagent consumption, and high degree of integration and automation. The system operation conditions were optimized using fluorescein as model sample. Its feasibility in biological analysis was preliminarily demonstrated in enzyme inhibition assay.
