复合材料T型接头力学性能分析及优化研究

T型接头作为常见的复合材料结构连接型式,其力学性能直接关系到结构的安全性。建立了考虑胶层的复合材料T型接头有限元模型,将仿真结果与试验图像进行对比,其变形形式和破坏模式与试验吻合较好。研究表明,在垂向载荷作用下,T型接头呈现"S"型弯曲;在蒙皮折角处以及端部胶接处出现应力集中;胶层剪应力两端大,中间出现低应力槽型区,弯曲正应力、等效应力呈现出双峰值特征;T型接头最有可能出现的破坏形式为胶层与蒙皮之间剥离,而芯材则由于应力集中引起剪切破坏或拉伸破坏。在折角处倒圆、在胶接处光滑过渡可以明显消除应力集中。     

铝合金T型接头激光+GMAW复合焊残余应力数值分析

目的 研究激光+GMAW复合焊中不同激光功率参数对铝合金T型接头残余应力的影响,从而提高焊接性能。方法 分别考虑了热弹塑性理论、传热学以及T型接头几何特性,建立了铝合金T型接头激光+电弧复合焊残余应力的数值分析模型。采用双椭球体热源模型表征电弧热输入与熔滴晗,采用锥体热源模型对激光深熔焊进行描述。基于所建立的T型接头模型,使用ANSYS有限元软件对12 mm厚铝合金激光+ GMAW焊T型接头残余应力进行模拟计算,并研究其分布特征;使用X射线衍射法对T型接头处的残余应力进行测量从而对所建模型的准确性进行验证。同时,对比了不同激光功率下铝合金T型接头对残余应力的影响规律。结果 当激光功率分别为2、3、4、5 kW时,铝合金T型接头路径L3上的纵向残余应力最大值分别为270、263、258、251 MPa,米塞斯-等效应力最大值分别为265、261、257、250 MPa。结论 后焊的焊缝A对焊缝B有明显的热处理作用,使应力明显降低;在T型接头焊缝及近缝区,横向残余应力和厚度方向残余应力峰值均比纵向残余应力峰值小,且随着激光功率的增大,焊缝及近缝区拉应力峰值不断减小。     

环口板加强后T型管节点落锤抗冲击试验研究

针对管节点抗冲击性能比较差的特点,工程常采用在主管和支管相贯区域焊接环口板的方法进行加强。本文以环口板加强和未加强的T型管节点为研究对象,进行落锤抗冲击比较试验研究。通过比较两类管节点的破坏模态和变形发展规律,并分析其冲击力、位移和应变时程曲线以及荷载-位移关系曲线,揭示环口板加强后管节点的抗冲击工作机理和冲击过程中的能量转换规律。研究成果可为正确评估该类管节点抗冲击性能和制定合理加固方法提供可靠的试验数据和设计建议。     

A welding wire for welding creep‐resisting chromium steel

The stress–strain state of brazed and welded T-joints is analysed by finite element analysis. It is shown that the brazed joints and also welded T-joints with incomplete penetration of the vertical sheet are characterized by the highly non-uniform distribution of service stresses. New designs of permanent joints, reducing the stress concentration, are proposed.     

高强钢三明治板T形接头焊剂片约束电弧焊电弧行为

文中基于高速摄像和焊接电信号采集系统，对焊剂片约束电弧焊接高强三明治板T形接头过程中的电弧行为进行了研究. 结果表明，通过焊剂片约束电弧焊接工艺可实现三明治板的加工制造，焊剂片在焊接过程中不仅有效解决了电弧攀升问题，还改变了电弧形貌与加热特性，显著增加了电弧稳定性；将电弧电压控制在23~29 V，焊接电流控制在240~320 A，坡口宽度控制在5~7 mm，在此工艺参数范围内，焊剂片熔化高度适中，电弧可获得良好的约束，电弧到坡口底部的距离与电弧到面板侧壁的距离相当，主要在坡口底部及侧壁根部稳定燃烧，可获得面板与芯板熔合良好T形接头.     

中间包层状撕裂产生的原因及预防措施

针对中间包焊接时产生层状撕裂问题，从产品结构、焊接工艺等方面分析了层状撕裂的原因，并制定相应的工艺措施，避免了层状撕裂的产生。     

Effect of Joint Geometry on the Behavior and Failure Modes of Sandwich T-Joints Under Transverse Static and Dynamic Loads

Due to wide spread application of adhesive T-joints in various industries, a review of properties and strength of their fracture modes under static and dynamic loadings is required. By defining the ability of failure in the joint material and fracture of adhesive in the numerical model, fracture modes of sandwich T-joints have been investigated. This paper presents numerical results on the performance of sandwich T-joints subjected to static tensile, static transverse, and dynamic transverse loading. The results of available experiments in the literature have been used to validate the detailed numerical models capable of simulating the damage processes observed. In general, the failure load predicted by the finite element (FE) analysis is within 5% of the experimental results.     

转向架构架标准焊接接头残余应力数值模拟

直接测试是获取焊接结构残余变形和残余应力的主要方法。以南京浦镇车辆有限公司的转向架构架为研究对象,利用有限元分析软件SYSWELD,对构架上面的T型接头和对接接头进行热-弹塑性有限元分析,得出残余应力大小和分布规律,并将模拟结果与实测结果进行对比,发现两者趋势吻合。     

3-D non-linear stress analysis on the adhesively bonded T-joints with embedded supports

In the present study, it is aimed to compare mechanical behaviors of T-joint types with embedded and non-embedded supports subjected to bending moment. For this purpose, after experimental studies on the two different T-joint types were conducted, stress analyses in the T-joints were performed with a three-dimensional finite element method by considering the geometrical non-linearity and the material non-linearities of the adhesive (DP460) and adherend (AA2024-T3). Finally, stress analyses and experimental results show that the variation of the geometry of the bonding zone, e.g., embedding the supports, would change the stress distributions and strength of the joint. Additionally, it is seen that T-joints with embedded supports carry 30% more load than T-joints with non-embedded supports although their bending stiffnesses decrease.     

Numerical analysis of temperature profile and weld dimensions in laser ＋ GMAW hybrid welding of aluminum alloy T-joint

The temperature fields in the transient state and weld dimensions in laser ＋ gas metal arc welding （GMAW） hybrid welding of aluminum alloy T-joint for different welding conditions were calculated using the developed heat source model, and the effect of welding speed on them was analyzed. The results show that the temperature field for the first weld pass only shows the feature of GMAW and the one for the second weld pass has the characteristics of both laser welding and GMAW. Welding speed can affect greatly weld dimensions and temperature distribution. When welding speed reaches 3.5 m/min, the fusion zones of two weld passes are separated and the maximum peak temperature of thermal cycle on the workpiece surface decreases largely.