For optimal design of mechanical clinching steel-aluminum joints,the back propagation(BP)neural network is used to research the mapping relationship between joining technique parameters including sheet thickness,sheet...For optimal design of mechanical clinching steel-aluminum joints,the back propagation(BP)neural network is used to research the mapping relationship between joining technique parameters including sheet thickness,sheet hardness,joint bottom diameter etc.,and mechanical properties of shearing and peeling in order to investigate joining technology between various material plates in the steel-aluminum hybrid structure car body.Genetic algorithm(GA)is adopted to optimize the back-propagation neural network connection weights.The training and validating samples are made by the BTM Tog-L-Loc system with different technologic parameters.The training samples'parameters and the corresponding joints'mechanical properties are supplied to the artificial neural network(ANN)for training.The validating samples'experimental data is used for checking up the prediction outputs.The calculation results show that GA can improve the model's prediction precision and generalization ability of BP neural network.The comparative analysis between the experimental data and the prediction outputs shows that ANN prediction models after training can effectively predict the mechanical properties of mechanical clinching joints and prove the feasibility and reliability of the intelligent neural networks system when used in the mechanical properties prediction of mechanical clinching joints.The prediction results can be used for a reference in the design of mechanical clinching steel-aluminum joints.展开更多
As one of the advanced and efficient means of joining,the clinching process is capable of joining sheets with different materials or different sheet thicknesses.In this article,a novel modified clinching process,i.e.,...As one of the advanced and efficient means of joining,the clinching process is capable of joining sheets with different materials or different sheet thicknesses.In this article,a novel modified clinching process,i.e.,the dieless clinching process,was executed to join AA6061 aluminum alloy with sheet thicknesses of 1.5,2.0,2.5 and 3.0 mm according to different sheet stack-ups.The geometrical characteristics,microhardness distribution,failure behavior,static strength,absorbed energy and instantaneous stiffness of the novel dieless joint were gotten and investigated.The results indicated that the sheet thickness ratio has a notable effect on the failure behavior and mechanical properties of the novel dieless clinched joint,and a relatively large sheet thickness ratio can improve the joint performance when joining sheets with different sheet thicknesses.展开更多
Clinching is a convenient and efficient cold forming process that can join two sheets without any additional part. This study establishes an intelligent system for optimizing the clinched joint. Firstly, a mathematica...Clinching is a convenient and efficient cold forming process that can join two sheets without any additional part. This study establishes an intelligent system for optimizing the clinched joint. Firstly, a mathematical model which introduces the ductile damage constraint to prevent cracking during clinching process is proposed.Meanwhile, an optimization methodology and its corresponding computer program are developed by integrated finite element model(FEM) and genetic algorithm(GA) approach. Secondly, Al6061-T4 alloy sheets with a thickness of 1.4 mm are used to verify this optimization system. The optimization program automatically acquires the largest axial strength which is approximately equal to 872 N. Finally, sensitivity analysis is implemented, in which the influence of geometrical parameters of clinching tools on final joint strength is analyzed. The sensitivity analysis indicates the main parameters to influence joint strength, which is essential from an industrial point of view.展开更多
To realize good point connection between high-strength steel and aluminum alloy,a process of drawing-upsetting-extrusion-clinching was proposed.First,the sheets were drawn;then,the bottom of the protrusion part was ex...To realize good point connection between high-strength steel and aluminum alloy,a process of drawing-upsetting-extrusion-clinching was proposed.First,the sheets were drawn;then,the bottom of the protrusion part was extruded,forming the necessary initial interlock;and finally,the protrusion part was reverse press clinched,forming a certain height of the clinched head.Taking DP980 high-strength steel and A15083 aluminum alloy as the connection objects and using the method of numerical simulation combined with experimental test,the mold was made,and the experiment was carried out on the basis of numerical simulation.The experimental results proved the feasibility of the process and the effectiveness of the numerical model.The simulation and experimental results show that the necessary interlock in the drawing-upsetting-extrusion stage is the premise of effective connection.The relative protrusion height should be around 55.6%after reverse-press-clinching.The best comprehensive mechanical properties measured by strength test were shear resistance of 2644 N,fatigue life of 24,535 times and peel resistance of 1522 N.Through failure analysis,the relationship between the interlock Tu and the neck thickness Tn of the joint with the best comprehensive mechanical properties was established as Tu=0.35Tn.The design method of die and process parameters when the sheet thickness changes was researched by numerical simulation.The results show that the clearance between the punch and the die and the bottom thickness are directly proportional to the sheet thickness,and the drawing depth is directly proportional to the punch radius.展开更多
China National Offshore Oil Co. (CNOOC) and two other companies had jointly signed two new production-sharing contracts to explore offshore oil and natural gas fields in Myanmar. CNOOCs Myanmar Ltd., China Huanqiu ...China National Offshore Oil Co. (CNOOC) and two other companies had jointly signed two new production-sharing contracts to explore offshore oil and natural gas fields in Myanmar. CNOOCs Myanmar Ltd., China Huanqiu Contracting and Engineering Corp. and Golden Aaron Pte. Ltd. of Singapore had signed contracts with展开更多
Numerical mechanical models used for design of structures and processes are very complex and high-dimensionally parametrised.The understanding of the model characteristics is of interest for engineering tasks and subs...Numerical mechanical models used for design of structures and processes are very complex and high-dimensionally parametrised.The understanding of the model characteristics is of interest for engineering tasks and subsequently for an efficient design.Multiple analysis methods are known and available to gain insight into existing models.In this contribution,selected methods from various fields are applied to a real world mechanical engineering example of a currently developed clinching process.The selection of introduced methods comprises techniques of machine learning and data mining,in which the utilization is aiming at a decreased numerical effort.The methods of choice are basically discussed and references are given as well as challenges in the context of meta-modelling and sensitivities are shown.An incremental knowledge gain is provided by a step-bystep application of the numerical methods,whereas resulting consequences for further applications are highlighted.Furthermore,a visualisation method aiming at an easy design guideline is proposed.These visual decision maps incorporate the uncertainty coming from the reduction of dimensionality and can be applied in early stage of design.展开更多
ZTE Corporation,the leading global provider of telecommunications equipment and network solutions,has announced the signing of its first commercial contract in Georgia for construction of a CDMA WLL network on May 23,
Clinching can be used for effective joining of different metallic materials, e.g., different grades of carbon and alloy steels, aluminum and its alloys and others. This is an alternative joining method to traditional ...Clinching can be used for effective joining of different metallic materials, e.g., different grades of carbon and alloy steels, aluminum and its alloys and others. This is an alternative joining method to traditional methods involving screws, rivets or welding. Clinching is applied in many fields of manufacturing industry. Future applications of clinch joining require advances in quality and among others things, combination with other processes, e.g., hybrid joining by clinching and adhesive bonding. Although the static strength of clinched joints is lower than that of the others joints （e.g., pressure welded joints）, the fatigue strength is comparable. But there is a lack of information about fatigue strength of clinched joints. The static and low cyclic fatigue strengths of mechanically clinched joints were determined experimentally. The load-displacement curves of static strength were compared with low cyclic fatigue strength curves. It was observed the effect of strain hardening for clinched joint of low carbon steels （DC4） under cyclic loading.展开更多
The final fight to pick the ultimate champibn of Senegalese wrestling, initially scheduled for January 13 at Pikine's National Wrestling Arena, finally took place at the Leopold Sedar Seng-hor Stadium Dakar.The wr...The final fight to pick the ultimate champibn of Senegalese wrestling, initially scheduled for January 13 at Pikine's National Wrestling Arena, finally took place at the Leopold Sedar Seng-hor Stadium Dakar.The wrestling match was moved from one venue to another to allow more spectators to enjoy the legendary fight between Balla Gaye 2 and Modou Lo,according to Gaston Mbengue,the fight's promoter.It took a lot of negotiations for this change of venue to be approved,he said.展开更多
Traditional manufacturing processes for bending and combining the upper and lower heat insulation plates for a car catalytic converter need two kinds of bending dies. This study was carried out to develop a single-act...Traditional manufacturing processes for bending and combining the upper and lower heat insulation plates for a car catalytic converter need two kinds of bending dies. This study was carried out to develop a single-action, two-step clinching system for clinching heat insulation plates. To design the operating mechanism for this clinching system, finite element analysis was used to estimate the bending load needed and to predict the bent shape of the heat insulation plate. Then a recovery and cushioning system was designed for the bending die. It is expected that this new process will improve the manufacturing quality of heat insulation plates and will reduce manufacturing cost. And a higher value-added technique for mold and pressing systems was introduced.展开更多
In numerical simulations of mechanical joining processes,such as clinching,modeling of material behavior is of decisive importance.In addition to the correct representation of plasticity and damage mechanisms,this pri...In numerical simulations of mechanical joining processes,such as clinching,modeling of material behavior is of decisive importance.In addition to the correct representation of plasticity and damage mechanisms,this primarily includes modeling of the friction behavior between the parts to be joined.This paper presents a method for experimental characterization and numerical modelling of friction behavior in mechanical joining processes like clinching.An axial torsion test was used to generate surface conditions on technological specimens,which also occur in the joined parts during the clinching process.This method also enables the independent investigation of friction-relevant parameters,such as relative velocity and contact pressure.The experimental datasets using aluminum material were transferred into an analytical approach.Combined with a modifiable user subroutine,it has been implemented into the finite element(FE)modeling using LS-Dyna.Validation was performed by numerically modeling the axial torsion test and comparing experimental and numerical results.Finally,the clinching process is simulated with the developed friction model and a standard friction model,and the results are compared.展开更多
The flat clinching process is attracting a growing attention in the joining field of lightweight materials because it avoids the geometric protrusion that appears in the conventional clinching process. In this paper, ...The flat clinching process is attracting a growing attention in the joining field of lightweight materials because it avoids the geometric protrusion that appears in the conventional clinching process. In this paper, the effects of sheet thickness and material on the mechanical properties of the clinched joint were studied. Al1060 and Al2024 sheets with 2 mm thickness were employed to develop the clinched joint by using different material configurations, and Al1060 sheets with 2.5- and 1.5-mm thicknesses were used to produce the clinched joint by using different thickness configurations. The clinched joints using various sheet configurations were sectioned, and dimensional analysis was conducted. Cross-tensile and shearing tests were carried out to analyze the mechanical properties of the clinched joint, including tensile strength, shearing strength, and absorbed energy. In addition, the failure modes of the clinched joints were discussed. Results indicated that the clinched joint with a stiff top sheet had increased static strength regardless of the test type. The clinched joint with a thick top sheet demonstrated lower static strength than the joint with a thick bottom sheet in the cross-tensile test. However, this result was reversed in the shearing tests. The flat clinching process has a great potential in joining dissimilar and various thickness materials.展开更多
The clinch–adhesive process,which combines mechanical clinching and adhesive bonding,is one of the most applied pro-cesses for joining aluminum alloy and steel in the manufacturing of vehicle bodies.In this hybrid pr...The clinch–adhesive process,which combines mechanical clinching and adhesive bonding,is one of the most applied pro-cesses for joining aluminum alloy and steel in the manufacturing of vehicle bodies.In this hybrid process,the clinching joints and adhesive bonds are coupled and influenced by each other,posing challenges to the process design and joining strength evaluation.To understand the influence of the clinching process on the performance of the adhesive layer,this study analyzes the mechanical behavior of clinch–adhesive joints between high-strength steel JSC780 and aluminum alloy A5052-H34 with different stack-up orientations and varying numbers of clinching points.The results reveal that,under the steel-on-top condition,the clinching process causes a discontinuous distribution of the adhesive layer,which significantly decreased the bonding strength.In contrast,under the aluminum-on-top condition,the clinching process has a lesser impact on the distribution of the adhesive layer,resulting in much higher strength than the steel-on-top condition.Simulation mod-els are constructed to quantify the effect of clinching points on the performance of the adhesive layer.The results highlight the need to consider diverse cohesive zone model parameters for the different stack orientations and clinching points in the design of clinch–adhesive aluminum alloy/steel structures.展开更多
基金supported by Guangdong Provincial Technology Planning of China(Grant No.2007B010400052)State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body of China(Grant No.30715006)Guangdong Provincial Key Laboratory of Automotive Engineering,China(Grant No.2007A03012)
文摘For optimal design of mechanical clinching steel-aluminum joints,the back propagation(BP)neural network is used to research the mapping relationship between joining technique parameters including sheet thickness,sheet hardness,joint bottom diameter etc.,and mechanical properties of shearing and peeling in order to investigate joining technology between various material plates in the steel-aluminum hybrid structure car body.Genetic algorithm(GA)is adopted to optimize the back-propagation neural network connection weights.The training and validating samples are made by the BTM Tog-L-Loc system with different technologic parameters.The training samples'parameters and the corresponding joints'mechanical properties are supplied to the artificial neural network(ANN)for training.The validating samples'experimental data is used for checking up the prediction outputs.The calculation results show that GA can improve the model's prediction precision and generalization ability of BP neural network.The comparative analysis between the experimental data and the prediction outputs shows that ANN prediction models after training can effectively predict the mechanical properties of mechanical clinching joints and prove the feasibility and reliability of the intelligent neural networks system when used in the mechanical properties prediction of mechanical clinching joints.The prediction results can be used for a reference in the design of mechanical clinching steel-aluminum joints.
基金Project(51805416) supported by the National Natural Science Foundation of ChinaProject(2019QNRC001) supported by the Young Elite Scientists Sponsorship Program by CAST,China+1 种基金Project(2021JJ20059) supported by the Hunan Provincial Natural Science Foundation for Excellent Young Scholars,ChinaProject(2019RS1002) supported by the Huxiang High-Level Talent Gathering Project of Hunan Province,China。
文摘As one of the advanced and efficient means of joining,the clinching process is capable of joining sheets with different materials or different sheet thicknesses.In this article,a novel modified clinching process,i.e.,the dieless clinching process,was executed to join AA6061 aluminum alloy with sheet thicknesses of 1.5,2.0,2.5 and 3.0 mm according to different sheet stack-ups.The geometrical characteristics,microhardness distribution,failure behavior,static strength,absorbed energy and instantaneous stiffness of the novel dieless joint were gotten and investigated.The results indicated that the sheet thickness ratio has a notable effect on the failure behavior and mechanical properties of the novel dieless clinched joint,and a relatively large sheet thickness ratio can improve the joint performance when joining sheets with different sheet thicknesses.
基金the Fundamental Research Funds for the Central Universities of China(No.CDJZR14130006)
文摘Clinching is a convenient and efficient cold forming process that can join two sheets without any additional part. This study establishes an intelligent system for optimizing the clinched joint. Firstly, a mathematical model which introduces the ductile damage constraint to prevent cracking during clinching process is proposed.Meanwhile, an optimization methodology and its corresponding computer program are developed by integrated finite element model(FEM) and genetic algorithm(GA) approach. Secondly, Al6061-T4 alloy sheets with a thickness of 1.4 mm are used to verify this optimization system. The optimization program automatically acquires the largest axial strength which is approximately equal to 872 N. Finally, sensitivity analysis is implemented, in which the influence of geometrical parameters of clinching tools on final joint strength is analyzed. The sensitivity analysis indicates the main parameters to influence joint strength, which is essential from an industrial point of view.
文摘To realize good point connection between high-strength steel and aluminum alloy,a process of drawing-upsetting-extrusion-clinching was proposed.First,the sheets were drawn;then,the bottom of the protrusion part was extruded,forming the necessary initial interlock;and finally,the protrusion part was reverse press clinched,forming a certain height of the clinched head.Taking DP980 high-strength steel and A15083 aluminum alloy as the connection objects and using the method of numerical simulation combined with experimental test,the mold was made,and the experiment was carried out on the basis of numerical simulation.The experimental results proved the feasibility of the process and the effectiveness of the numerical model.The simulation and experimental results show that the necessary interlock in the drawing-upsetting-extrusion stage is the premise of effective connection.The relative protrusion height should be around 55.6%after reverse-press-clinching.The best comprehensive mechanical properties measured by strength test were shear resistance of 2644 N,fatigue life of 24,535 times and peel resistance of 1522 N.Through failure analysis,the relationship between the interlock Tu and the neck thickness Tn of the joint with the best comprehensive mechanical properties was established as Tu=0.35Tn.The design method of die and process parameters when the sheet thickness changes was researched by numerical simulation.The results show that the clearance between the punch and the die and the bottom thickness are directly proportional to the sheet thickness,and the drawing depth is directly proportional to the punch radius.
文摘China National Offshore Oil Co. (CNOOC) and two other companies had jointly signed two new production-sharing contracts to explore offshore oil and natural gas fields in Myanmar. CNOOCs Myanmar Ltd., China Huanqiu Contracting and Engineering Corp. and Golden Aaron Pte. Ltd. of Singapore had signed contracts with
文摘Numerical mechanical models used for design of structures and processes are very complex and high-dimensionally parametrised.The understanding of the model characteristics is of interest for engineering tasks and subsequently for an efficient design.Multiple analysis methods are known and available to gain insight into existing models.In this contribution,selected methods from various fields are applied to a real world mechanical engineering example of a currently developed clinching process.The selection of introduced methods comprises techniques of machine learning and data mining,in which the utilization is aiming at a decreased numerical effort.The methods of choice are basically discussed and references are given as well as challenges in the context of meta-modelling and sensitivities are shown.An incremental knowledge gain is provided by a step-bystep application of the numerical methods,whereas resulting consequences for further applications are highlighted.Furthermore,a visualisation method aiming at an easy design guideline is proposed.These visual decision maps incorporate the uncertainty coming from the reduction of dimensionality and can be applied in early stage of design.
文摘ZTE Corporation,the leading global provider of telecommunications equipment and network solutions,has announced the signing of its first commercial contract in Georgia for construction of a CDMA WLL network on May 23,
文摘Clinching can be used for effective joining of different metallic materials, e.g., different grades of carbon and alloy steels, aluminum and its alloys and others. This is an alternative joining method to traditional methods involving screws, rivets or welding. Clinching is applied in many fields of manufacturing industry. Future applications of clinch joining require advances in quality and among others things, combination with other processes, e.g., hybrid joining by clinching and adhesive bonding. Although the static strength of clinched joints is lower than that of the others joints （e.g., pressure welded joints）, the fatigue strength is comparable. But there is a lack of information about fatigue strength of clinched joints. The static and low cyclic fatigue strengths of mechanically clinched joints were determined experimentally. The load-displacement curves of static strength were compared with low cyclic fatigue strength curves. It was observed the effect of strain hardening for clinched joint of low carbon steels （DC4） under cyclic loading.
文摘The final fight to pick the ultimate champibn of Senegalese wrestling, initially scheduled for January 13 at Pikine's National Wrestling Arena, finally took place at the Leopold Sedar Seng-hor Stadium Dakar.The wrestling match was moved from one venue to another to allow more spectators to enjoy the legendary fight between Balla Gaye 2 and Modou Lo,according to Gaston Mbengue,the fight's promoter.It took a lot of negotiations for this change of venue to be approved,he said.
基金supported by research funds from Dong-A University
文摘Traditional manufacturing processes for bending and combining the upper and lower heat insulation plates for a car catalytic converter need two kinds of bending dies. This study was carried out to develop a single-action, two-step clinching system for clinching heat insulation plates. To design the operating mechanism for this clinching system, finite element analysis was used to estimate the bending load needed and to predict the bent shape of the heat insulation plate. Then a recovery and cushioning system was designed for the bending die. It is expected that this new process will improve the manufacturing quality of heat insulation plates and will reduce manufacturing cost. And a higher value-added technique for mold and pressing systems was introduced.
基金funded by the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)-TRR 285/2-Project-ID 418701707.
文摘In numerical simulations of mechanical joining processes,such as clinching,modeling of material behavior is of decisive importance.In addition to the correct representation of plasticity and damage mechanisms,this primarily includes modeling of the friction behavior between the parts to be joined.This paper presents a method for experimental characterization and numerical modelling of friction behavior in mechanical joining processes like clinching.An axial torsion test was used to generate surface conditions on technological specimens,which also occur in the joined parts during the clinching process.This method also enables the independent investigation of friction-relevant parameters,such as relative velocity and contact pressure.The experimental datasets using aluminum material were transferred into an analytical approach.Combined with a modifiable user subroutine,it has been implemented into the finite element(FE)modeling using LS-Dyna.Validation was performed by numerically modeling the axial torsion test and comparing experimental and numerical results.Finally,the clinching process is simulated with the developed friction model and a standard friction model,and the results are compared.
基金This research work was supported by the National Natural Science Foundation of China(Grant No.51805416)the Young Elite Scientists Sponsorship Program by CAST,the Natural Science Foundation of Hunan Province,China(Grant No.2020JJ5716)+2 种基金the Natural Science Basic Research Plan in Shaanxi Province of China(Grant No.2019JQ-372)the Research Fund of State Key Laboratory of High Performance Complex Manufacturing(Grant No.ZZYJKT2019-01)the Huxiang High-Level Talent Gathering Project of Hunan Province,China(Grant No.2019RS1002).
文摘The flat clinching process is attracting a growing attention in the joining field of lightweight materials because it avoids the geometric protrusion that appears in the conventional clinching process. In this paper, the effects of sheet thickness and material on the mechanical properties of the clinched joint were studied. Al1060 and Al2024 sheets with 2 mm thickness were employed to develop the clinched joint by using different material configurations, and Al1060 sheets with 2.5- and 1.5-mm thicknesses were used to produce the clinched joint by using different thickness configurations. The clinched joints using various sheet configurations were sectioned, and dimensional analysis was conducted. Cross-tensile and shearing tests were carried out to analyze the mechanical properties of the clinched joint, including tensile strength, shearing strength, and absorbed energy. In addition, the failure modes of the clinched joints were discussed. Results indicated that the clinched joint with a stiff top sheet had increased static strength regardless of the test type. The clinched joint with a thick top sheet demonstrated lower static strength than the joint with a thick bottom sheet in the cross-tensile test. However, this result was reversed in the shearing tests. The flat clinching process has a great potential in joining dissimilar and various thickness materials.
基金supports of the National Key Research and Development Program of China(2022YFB3402200)Young Elite Scientists Sponsorship Program by CAST(2022-2024QNRC001)Shanghai Pujiang Program(22PJ1407200)。
文摘The clinch–adhesive process,which combines mechanical clinching and adhesive bonding,is one of the most applied pro-cesses for joining aluminum alloy and steel in the manufacturing of vehicle bodies.In this hybrid process,the clinching joints and adhesive bonds are coupled and influenced by each other,posing challenges to the process design and joining strength evaluation.To understand the influence of the clinching process on the performance of the adhesive layer,this study analyzes the mechanical behavior of clinch–adhesive joints between high-strength steel JSC780 and aluminum alloy A5052-H34 with different stack-up orientations and varying numbers of clinching points.The results reveal that,under the steel-on-top condition,the clinching process causes a discontinuous distribution of the adhesive layer,which significantly decreased the bonding strength.In contrast,under the aluminum-on-top condition,the clinching process has a lesser impact on the distribution of the adhesive layer,resulting in much higher strength than the steel-on-top condition.Simulation mod-els are constructed to quantify the effect of clinching points on the performance of the adhesive layer.The results highlight the need to consider diverse cohesive zone model parameters for the different stack orientations and clinching points in the design of clinch–adhesive aluminum alloy/steel structures.
