In the aerospace industry,integrated aluminium alloy plates and stiffened panels with high accuracy and performance attract significant interest.To manufacture these panels as integrity with high accuracy,multiple pro...In the aerospace industry,integrated aluminium alloy plates and stiffened panels with high accuracy and performance attract significant interest.To manufacture these panels as integrity with high accuracy,multiple processes need to be utilised,such as machining,welding and forming.During the whole manufacturing chain,residual stresses can be generated and redistributed in the components among different processes.The residual stress would significantly affect the shapes and properties of the final products.Currently,these great effects are not well considered in the design and manufacturing processes.This paper aims to draw a general understanding of the residual stress generated in the pre-manufacturing processes and its effects on subsequent manufacturing processes.The mechanisms and distributions of residual stresses generated in typical premanufacturing processes of structural panels,including machining,welding and additive manufacturing(AM),are firstly summarised.The detailed effects of generated residual stresses on distortion and application properties in subsequent manufacturing processes are then concluded.In addition,current methods developed for the investigation of residual stress effect in multi-processes manufacturing are critically reviewed,including experimental,analytical,finite element(FE)and machine learning methods.Furthermore,the future development trend of methods for residual stress consideration and control in the design of manufacturing processes is summarised,providing comprehensive guidance to achieve the high accurate manufacturing of aluminium alloy structural components.展开更多
The quantitative evaluation of multi-process collaborative operation is of great significance for the improvement of production planning and scheduling in steelmaking–continuous casting sections(SCCSs). However, this...The quantitative evaluation of multi-process collaborative operation is of great significance for the improvement of production planning and scheduling in steelmaking–continuous casting sections(SCCSs). However, this evaluation is difficult since it relies on an in-depth understanding of the operating mechanism of SCCSs, and few existing methods can be used to conduct the evaluation, due to the lack of full-scale consideration of the multiple factors related to the production operation. In this study, three quantitative models were developed, and the multiprocess collaborative operation level was evaluated through the laminar-flow operation degree, the process matching degree, and the scheduling strategy availability degree. Based on the evaluation models for the laminar-flow operation and process matching levels, this study investigated the production status of two steelmaking plants, plants A and B, based on actual production data. The average laminar-flow operation(process matching) degrees of SCCSs were obtained as 0.638(0.610) and 1.000(0.759) for plants A and B, respectively, for the period of April to July 2019. Then, a scheduling strategy based on the optimization of the furnace-caster coordinating mode was suggested for plant A. Simulation experiments showed higher availability than the greedy-based and manual strategies. After the proposed scheduling strategy was applied,the average process matching degree of the SCCS of plant A increased by 4.6% for the period of September to November 2019. The multi-process collaborative operation level was improved with fewer adjustments and interruptions in casting.展开更多
Simulating charged particle motion through the elements is necessary to understand modern particle accelerators. The particle numbers and the circling turns in a synchrotron are huge, and a simulation can be timeconsu...Simulating charged particle motion through the elements is necessary to understand modern particle accelerators. The particle numbers and the circling turns in a synchrotron are huge, and a simulation can be timeconsuming. Open multi-processing(Open MP) is a convenient method to speed up the computing of multi-cores for computers based on share memory model. Using message passing interface(MPI) which is based on nonuniform memory access architecture, a coarse grain parallel algorithm is set up for the Accelerator Toolbox(AT)for dynamic tracking processes. The computing speedup of the tracking process is 3.77 times with a quad-core CPU computer and the speed almost grows linearly with the number of CPU.展开更多
聚醚醚酮(polyetheretherketone,PEEK)材料作为典型的轻质高性能聚合物材料,在医疗航空航天等领域获得了大量应用,PEEK材料的增材制造技术可以实现复杂零部件的结构功能一体化制造。针对聚醚醚酮粉末床熔融(powder bed fusion,PBF)系统...聚醚醚酮(polyetheretherketone,PEEK)材料作为典型的轻质高性能聚合物材料,在医疗航空航天等领域获得了大量应用,PEEK材料的增材制造技术可以实现复杂零部件的结构功能一体化制造。针对聚醚醚酮粉末床熔融(powder bed fusion,PBF)系统加工温度高、易翘曲的难题,开展了聚醚醚酮粉末床熔融系统多工艺参数优化与成形性能研究,通过工艺成形过程模拟仿真,揭示了激光功率等核心参数对温度场的影响规律。在成形工艺仿真基础上,开展了成形工艺参数优化试验,建立了工艺参数与拉伸力学性能以及翘曲率的对应关系,获得了拉伸强度86 MPa,断裂伸长率3.7%的优异力学性能,并最终实现了颅骨植入物的高精度增材制造。展开更多
Microbially induced calcite precipitation(MICP)and Enzyme induced calcite precipitation(EICP)techniques were implemented to reinforce the large-scale calcareous sand in this study.Then a coupled numerical model to pre...Microbially induced calcite precipitation(MICP)and Enzyme induced calcite precipitation(EICP)techniques were implemented to reinforce the large-scale calcareous sand in this study.Then a coupled numerical model to predict the biochemical reactions and hydraulic characteristics of MICP and EICP reactions was proposed and verified by physical experiments.Results showed that:This model could describe the variations of bacteria,calcium,calcite,permeability over time reasonably.It is necessary to consider the influence of the calculation domain scale when simulating the convection-diffusionreaction in the multi-process of MICP and EICP reactions.The numerical and experimental values of calcite content are 0.841 g/cm^(3) and 0.861 g/cm^(3) for MICP-reinforced sand,0.263 g/cm^(3) and 0.227 g/cm^(3) for EICP-reinforced sand after 192 h of reaction.The reaction rate k_(rea) is an important parameter to control the calcite content.Accordingly,the permeability coefficient of MICP and EICP reinforced calcareous sand decreases by 32%and 18%.Due to the influence of substance transportation and calcite precipitation,the calcite shows a trend of decreasing firstly and then increasing with the enhancing of the initial permeability coefficient in biochemical reactions.The optimal injecting ratio q11:q12 in this study is 100:300 mL/min.The process for the application of MICP and EICP coupled numerical model is also recommended,which provides reference for engineering projects in ground improvement.展开更多
基金co-supported by the National Natural Science Foundation of China(No.52005020)Guangdong Basic and Applied Basic Research Foundation(No.2019A1515110851).
文摘In the aerospace industry,integrated aluminium alloy plates and stiffened panels with high accuracy and performance attract significant interest.To manufacture these panels as integrity with high accuracy,multiple processes need to be utilised,such as machining,welding and forming.During the whole manufacturing chain,residual stresses can be generated and redistributed in the components among different processes.The residual stress would significantly affect the shapes and properties of the final products.Currently,these great effects are not well considered in the design and manufacturing processes.This paper aims to draw a general understanding of the residual stress generated in the pre-manufacturing processes and its effects on subsequent manufacturing processes.The mechanisms and distributions of residual stresses generated in typical premanufacturing processes of structural panels,including machining,welding and additive manufacturing(AM),are firstly summarised.The detailed effects of generated residual stresses on distortion and application properties in subsequent manufacturing processes are then concluded.In addition,current methods developed for the investigation of residual stress effect in multi-processes manufacturing are critically reviewed,including experimental,analytical,finite element(FE)and machine learning methods.Furthermore,the future development trend of methods for residual stress consideration and control in the design of manufacturing processes is summarised,providing comprehensive guidance to achieve the high accurate manufacturing of aluminium alloy structural components.
基金financially supported by the National Natural Science Foundation of China (Nos.50874014 and 51974023)the Fundamental Research Funds for Central Universities (No.FRF-BR-17-029A)。
文摘The quantitative evaluation of multi-process collaborative operation is of great significance for the improvement of production planning and scheduling in steelmaking–continuous casting sections(SCCSs). However, this evaluation is difficult since it relies on an in-depth understanding of the operating mechanism of SCCSs, and few existing methods can be used to conduct the evaluation, due to the lack of full-scale consideration of the multiple factors related to the production operation. In this study, three quantitative models were developed, and the multiprocess collaborative operation level was evaluated through the laminar-flow operation degree, the process matching degree, and the scheduling strategy availability degree. Based on the evaluation models for the laminar-flow operation and process matching levels, this study investigated the production status of two steelmaking plants, plants A and B, based on actual production data. The average laminar-flow operation(process matching) degrees of SCCSs were obtained as 0.638(0.610) and 1.000(0.759) for plants A and B, respectively, for the period of April to July 2019. Then, a scheduling strategy based on the optimization of the furnace-caster coordinating mode was suggested for plant A. Simulation experiments showed higher availability than the greedy-based and manual strategies. After the proposed scheduling strategy was applied,the average process matching degree of the SCCS of plant A increased by 4.6% for the period of September to November 2019. The multi-process collaborative operation level was improved with fewer adjustments and interruptions in casting.
基金Supported by the National Natural Science Foundation of China(No11105214)
文摘Simulating charged particle motion through the elements is necessary to understand modern particle accelerators. The particle numbers and the circling turns in a synchrotron are huge, and a simulation can be timeconsuming. Open multi-processing(Open MP) is a convenient method to speed up the computing of multi-cores for computers based on share memory model. Using message passing interface(MPI) which is based on nonuniform memory access architecture, a coarse grain parallel algorithm is set up for the Accelerator Toolbox(AT)for dynamic tracking processes. The computing speedup of the tracking process is 3.77 times with a quad-core CPU computer and the speed almost grows linearly with the number of CPU.
文摘聚醚醚酮(polyetheretherketone,PEEK)材料作为典型的轻质高性能聚合物材料,在医疗航空航天等领域获得了大量应用,PEEK材料的增材制造技术可以实现复杂零部件的结构功能一体化制造。针对聚醚醚酮粉末床熔融(powder bed fusion,PBF)系统加工温度高、易翘曲的难题,开展了聚醚醚酮粉末床熔融系统多工艺参数优化与成形性能研究,通过工艺成形过程模拟仿真,揭示了激光功率等核心参数对温度场的影响规律。在成形工艺仿真基础上,开展了成形工艺参数优化试验,建立了工艺参数与拉伸力学性能以及翘曲率的对应关系,获得了拉伸强度86 MPa,断裂伸长率3.7%的优异力学性能,并最终实现了颅骨植入物的高精度增材制造。
基金supports from the National Key R&D Program of China(Grant No.2023YFB4203301)National Natural Science Foundation of China(Grant No.52238008)Postdoctoral Fellowship Program of CPSF(Grant No.GZC20241516).
文摘Microbially induced calcite precipitation(MICP)and Enzyme induced calcite precipitation(EICP)techniques were implemented to reinforce the large-scale calcareous sand in this study.Then a coupled numerical model to predict the biochemical reactions and hydraulic characteristics of MICP and EICP reactions was proposed and verified by physical experiments.Results showed that:This model could describe the variations of bacteria,calcium,calcite,permeability over time reasonably.It is necessary to consider the influence of the calculation domain scale when simulating the convection-diffusionreaction in the multi-process of MICP and EICP reactions.The numerical and experimental values of calcite content are 0.841 g/cm^(3) and 0.861 g/cm^(3) for MICP-reinforced sand,0.263 g/cm^(3) and 0.227 g/cm^(3) for EICP-reinforced sand after 192 h of reaction.The reaction rate k_(rea) is an important parameter to control the calcite content.Accordingly,the permeability coefficient of MICP and EICP reinforced calcareous sand decreases by 32%and 18%.Due to the influence of substance transportation and calcite precipitation,the calcite shows a trend of decreasing firstly and then increasing with the enhancing of the initial permeability coefficient in biochemical reactions.The optimal injecting ratio q11:q12 in this study is 100:300 mL/min.The process for the application of MICP and EICP coupled numerical model is also recommended,which provides reference for engineering projects in ground improvement.
