Prediction of residual stresses induced by low transformation temperature weld wires and its validation using the contour method

Welding residual stresses are one of the main factors influencing the engineering properties of welded structures, and should be taken into account during designing and manufacturing products such as ships, bridges, etc. Recently, both computational and experimental methods play a significant role for providing residual stresses. The contour method (CM) became one of the most powerful techniques that can provide measurement of residual stresses normal to a plane of interest. In this method a component is cut at any plane of interest. Displacements normal to the cut surface are measured and then processed. Using the Thermal–Elastic–Plastic Finite Element Method (TEP-FEM), residual stresses after welding can be predicted. As well as, the elastic FEM can be used to reproduce residual stresses from measured longitudinal displacements in the CM.The main objective of this paper is to evaluate the effectiveness of different low transformation temperature (LTT) weld wires using TEP-FEM and the CM. In the simulation part, a computational approach is developed to numerically simulate both of welding and the CM. In the TEP-FEM, phase transformation is considered for LTT welds, additionally volume change and variation of mechanical properties with temperature are considered. In the simulated CM, welded specimens to be measured are replaced by TEP-FE models. Then the procedure of the CM is examined before applying it to real measurements. The simulated CM successfully predicted how the CM would reconstruct the residual stresses if applied experimentally. In the experimental part, welding is conducted using conventional and various LTT weld wires. Longitudinal residual stresses produced due to welding are measured using the CM. The results of TEP-FE simulation and the CM show the effectiveness of the different LTT weld wires in introducing compressive stresses in the weld. It is also observed that the applied LTT weld wires, which have almost the same martensitic transformation start temperatures, do not show big difference in the induced compressive residual stresses in the weld metal.     

CSR和CSR-H的焊接系数研究

归纳和定性分析CSR和CSR-H的焊接系数,确定焊接系数的影响因素。提出焊接系数利用因子的有限元分析方法,确定焊缝强度的应力标准。进行了13艘CSR船舶船体结构焊缝应力的提取和焊接系数利用因子的计算,获得CSR船体结构各类角焊缝利用因子的统计结果。通过短柱和板条梁的焊缝强度试验,验证焊缝强度标准及焊缝应力公式的正确性和适用性。     

海洋钢结构的焊接质量控制

近几年，石油和天然气价格推动了世界海洋石油工业的高速发展，海洋钢结构作为海上油气钻采的支撑结构物，其建造量逐年递增。由于海洋钢结构特殊的服役环境，且随着向深水海域的迈进，海洋钢结构的服役环境趋向于更为恶劣，相比常规钢结构而言，其对焊接质量的要求更为严格。对海洋钢结构的结构类型、焊接结构的最新设计理念以及焊接质量的控制措施进行了阐述。掌握焊接参数对焊接质量的影响以及掌握焊接缺陷产生的机理是控制海洋钢结构焊接质量的关键。     

JD117型异步牵引电动机的工艺难点及对策

JD117型异步牵引电动机是为动力分散型交流传动电动车组设计的。电机研制过程中在机座的加工和线圈的制作等方面进行了许多的工艺技术研究工作。同时，在异步牵引电动机转子制造的关键环节——导条与端环焊接方面，采用了先进的中频整体感应焊接技术。     

TIG熔修提高船体钢焊接接头腐蚀疲劳抗力的研究

对经ＴＩＧ熔修和未经ＴＩＧ熔修的４５ｋｇ级船体钢焊接试样进行了全面模拟实船肥役条件的腐蚀疲劳实验研究。结果表明，按一定工艺规范熔修处理的焊接接头，其海水介质腐蚀疲劳抗力得到了显著的提高。     

肋板对焊接结构疲劳强度影响的分析研究

对带有肋板的焊接结构的疲劳强度进行了分析研究,阐明了肋板对焊接结构疲劳强度的影响,提出了改善带肋板焊接结构疲劳强度的措施。     

岸桥箱型梁制作工艺及质量控制

箱型梁是岸桥钢结构重要部件。为保证其制作质量,要对其制作过程进行质量控制。详细介绍桥吊制作过程中下料、装配、焊接、热矫等工艺的质量控制要点。     

平面舱壁周界的焊缝研究

利用焊缝计算模型法、有限元法对CSR-OT规范中平面舱壁周界焊接系数进行实船验证,以一艘阿芙拉型双壳油船平面舱壁结构为例,在不同工况荷载作用下,计算出平面舱壁对内底板处焊缝的焊缝强度利用因子。两种算法的计算结果表明：规范中此处焊接系数满足强度要求且有安全余量。该研究对进一步理解CSR-OT规范焊接系数规格表具有一定参考价值。     

海洋工程中常见焊接缺陷的成因探讨及对策

海洋工程钢结构制造过程中焊接接头、焊缝和热影响区是最容易产生各种缺陷的地方.缺陷,顾名思义是一种欠缺、不足、不完善的地方,也包括物体的损伤.焊接缺陷可定义为不完善焊接施工所导致的工件使用性能的不连续性;也可定义为由于原有或积累的影响,使部件或产品不能满足最低验收标准或规程的一种或多种不连续[焊接缺陷的研究是伴随着焊缝质量检测方法的进步而发展的];故对焊接缺陷及其缺陷对焊接构件承载力的影响程度的研究是很有必要的.该文以外观检测方式、用PL19-3项目中出现的焊接缺陷,探求钢结构焊接缺陷类型、特点及其产生缺陷的成因;并通过具体的案例进行分析,从而达到减少缺陷产生及保证工程质量的目的.     

船舶结构有限元模型局部修正方法研究

为了实现船舶结构有限元模型中开孔和趾端的快速建模,针对有限元网格的局部区域细化方法,基于Patran平台设计开发参数化建模程序。实测证明,该程序能够快速准确地创建开孔和趾端,在一定程度上减轻审图验船人员的繁琐重复劳动,提高审图效率。