Mechanical Properties Prediction of the Mechanical Clinching Joints Based on Genetic Algorithm and BP Neural Network

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.

Data Mining and Machine Learning Methods Applied to A Numerical Clinching Model

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.

Clinching Victory

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.

Drawing-upsetting-extrusion-clinching of high-strength steel and aluminum alloy

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.

Optimization of Clinching Tools by Integrated Finite Element Model and Genetic Algorithm Approach

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.

铝车身自动冷连接技术的柔性应用

目前市面上针对铝车身的连接工艺,有自冲铆接、流钻螺钉拧紧、无钉铆接等,在工艺及设备成熟应用的基础上,探究不同工艺的互换性,满足各大主机厂对铝连接技术的柔性需求。主要介绍在已建立的铝连接试验阵地中,通过对介质、设备接口的快速通断,将自冲铆接设备、流钻螺钉拧紧设备、无钉铆接设备实现在同一台机器人上进行柔性切换的目的。

Failure behavior and mechanical properties of novel dieless clinched joints with different sheet thickness ratios

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.

Low Fatigue Strength of Clinch Joints

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.

Microstructure evolution of AA5052 joint failure process and mechanical performance after reconditioning with tubular rivet

To extend the service life of the clinched joint,a reconditioning process conducted with an additional tubular rivet was proposed in this work.Different reconditioning forces were employed to produce dissimilar reconditioned joints by experimental method.The experimental results indicated that the neck fracture was the common failure mode of both original clinched and reconditioned joints.Compared with the original clinched joint,the shearing strength of the reconditioned joint produced by a reconditioning force of 40 kN increased from 1810.5 to 1986.47 N,and the energy absorption increased from 2.34 to 3.46 J.The range of effective reconditioning force was from 35 to 40 kN and 40 kN was the best choice for reconditioning the AA5052 failed joints.The mechanical properties of the reconditioned joints are obviously better than those of the original clinched joints,which fully demonstrates that the reconditioning method proposed in this work has a broad prospect of industrial application.

Oils Firms Clinch Large Overseas Deals

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

ZTE Clinches First CDMA Contract with Georgia's UTG

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,

试制阶段冲铆工艺参数开发及质量监控方法

汽车车身中新材料、新工艺的应用越来越广泛。例如:0.5mm钢板的使用,铸铝零件、铝冲压件的使用,SRP、FDS等连接工艺的应用。新材料的性能、新工艺的参数在试制阶段的充分验证,不仅可以减小后期项目阶段的风险而且可以加快项目进度。TOX Clinch一般用在厚度差异较大钢板的冷连接上,本文介绍了在试制阶段如何选择TOX Clinch的模具型号,如何确定压力参数,进行质量监控的方法等。该方法同样适用于其他新型连接工艺关键参数的确定过程。

Mechanical Performance Evaluation of Multi‑Point Clinch–Adhesive Joints of Aluminum Alloy A5052‑H34 and High‑Strength Steel JSC780

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.

Effects of sheet thickness and material on the mechanical properties of flat clinched joint

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.

车身Clinch工艺的返修方法研究

1 Clinch连接方式及优点分析传统点焊在钢板连接方面暴露出来的问题较多,譬如,连接可靠性差,很难连接多层板件及有镀层的板件或铝、铜及不锈钢板件;无法连接喷漆板件、不同标准的板件、厚度差异大的板件及有中间夹层的板件;