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81.
Thermal effects on welded joints between fiber-reinforced thermoplastics (FRTPs) and metals have been investigated theoretically and experimentally. Because FRTPs use thermoplastics as the matrix resin, they have advantages over fiber-reinforced thermoset plastics (FRPs or FRSPs), including the ability to be welded. When dissimilar materials are welded together, however, thermal stress occurs due to the different thermal expansions of the materials and affects the energy release rate of the joint. Therefore, a method for evaluating the true energy release rate, including the effect of thermal stress, is necessary for strength evaluation tests. Although several theories that compensate for the thermal stress and evaluate the true energy release rate have already been proposed, they require parameters that are difficult to measure. Therefore, it is difficult to apply them in experimental investigations. In this article, a theoretical method with easily measurable parameters is proposed to calculate the energy release rate of welded double cantilever beam (DCB) joints. The effect of the thermal stress on the critical energy release rate is discussed in terms of the experimental results of a welded DCB specimen composed of a FRTP and an aluminum alloy. 相似文献
82.
83.
Yu. N. Saraev V. P. Bezborodov S. V. Gladkovskiy N. I. Golikov 《Welding International》2017,31(8):631-636
The concept of investigations carried out to increase the reliability of metallic structures designed for operation in the conditions of low climatic temperatures is described. The worldwide tendencies in the investigation of the processes of the formation and fracture of materials and components at low climatic temperatures are analysed. The main methodological approaches, directed at ensuring high parameters of the service reliability of structures in low carbon, low alloy steels are outlined. The experimental data obtained in this area are analysed. The directions for further experimental and theoretical studies are indicated. 相似文献
84.
A study of port plug distortion resulting from narrow gap combined GTAW & SMAW and Electron Beam Welding was carried out. Thermomechanical finite element analysis of port plug becomes virtually impossible because of the requirement of huge number of nodes and elements. Hence an analysis method based on the concept of inherent strain was used in this work. The computational time required was about 40-50 min only in a Core (TM) 2 Duo, 2.66 GHz computer with 2 GB RAM, which otherwise was not possible with other conventional computation techniques. As was expected the overall distortion due to EB welding was found to be less compared to that of narrow gap GTAW & SMAW. 相似文献
85.
针对受损的水轮机叶片等具有空间复杂曲面结构,在其安装位置直接进行修复工作,设计了一种基于移动平台的焊接机器人虚拟样机。为确定焊枪末端与机器人6个关节之间的运动关系,建立虚拟样机DH坐标系,借助Matlab软件得到运动学方程正、逆解。将在Solid Works软件中建立的焊接机器人三维模型,导入ADAMS仿真软件进行运动学分析。仿真结果表明:机器人在狭窄空间启动时,由滑动、转动关节运动引起的焊枪末端空间位移变化小,速度、加速度曲线变化平缓,无任何突变,证明了该虚拟样机设计的有效性,满足基坑内的焊接工作要求。 相似文献
86.
87.
在白车身工艺规划过程中,积累了大量车身焊接工艺数据。为了提取这些知识采用数据挖掘方法发现其中所需的工艺规则。首先采用粗糙集对工艺属性进行约简,删除对工艺决策没有影响的属性;然后采用关联规则挖掘对焊接方法有影响的工艺规则;最后用实例验证了该方法的有效性。 相似文献
88.
Alejandro García Rodríguez Jorge V. Miguel Oria Alexis Delgado Gómez 《Welding International》2016,30(7):527-534
The present work is based on an assessment of experimentally obtained results from the application of different methods of evaluation, reported in the specialised literature, of the electrical charge transference stability in the arc. A simple factorial design, taking the welding current as independent variable, was applied to the process with an AWS A5.1 E6013 electrode. The welds were carried out in the flat position by a gravity device. It was possible to obtain criteria to classify the electrical charge transference stability of the process by digital signal processing and a statistical technique. The outcome was based on visual inspection and morphologic studies. It was concluded that amongst the considered parameters, the average value of the arc conductivity during reignition peaks and the quantity of reignition peaks are the more representative indices, both from statistics and from phenomenological points of view. This finding is validated by the fact that the bead morphology and the stability analysis of the electrical charge transference process coincides with the fact that the 160 A (for 4 mm-diameter electrodes) is the most stable regime. 相似文献
89.
The methods of welding marine titanium alloys do not differ greatly from the commercial methods of welding titanium ensuring reliable protection against the environment. Welding is carried out either in inert gases or in vacuum. Nevertheless, there are a number of technological and constructional special features of welded joints associated with the working conditions of marine structures in the actual service conditions which are discussed in this article. 相似文献
90.
针对矿用液压支架油缸内壁局部缺陷修复,设计一种能深入液压支架油缸筒内进行内壁修复的焊接机械臂。基于改进D-H参数建模方法,对设计的内表面修复焊接机械臂进行运动学建模,并求解了内表面修复焊接机械臂的正、逆运动学。借助MATLAB软件,采用蒙特卡洛法,对该焊接机械臂的有效工作空间进行了仿真分析,利用Robotics Toolbox工具箱对油缸内壁缺陷修复机械臂进行关节轨迹规划,通过仿真得到各关节的角位移、角速度、角加速度曲线。仿真结果表明:该机械臂运行平稳,轨迹连续,满足运动学要求。 相似文献