共查询到16条相似文献,搜索用时 187 毫秒
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本文对高湿度下的药芯焊丝角焊缝质量进行研究,首先介绍在高湿度状态下模拟舱壁板与球扁钢角焊缝药芯焊丝焊接试验情况.然后分析焊缝质量及扩散氢含量检测结果.试验结果显示:在高湿度情况下,焊缝表面出现大量气孔,降低了焊缝质量;药芯焊丝在高空气湿度下暴露24小时候,焊缝中扩散氢大量增加,增加了氢致裂纹的风险.最后经过试验研究与分析,得出结论,制定防护措施. 相似文献
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角焊缝角变形产生机制的研究 总被引:1,自引:1,他引:0
以T形焊接接头为算例,用有限元数值计算方法研究了六个固有应变分量各自对角焊缝角变形的作用效应,发现导致角变形产生的主要因素是与焊缝平行的平面内垂直于焊缝方向的固有剪切应变分量;将该固有剪切应变分量以均匀和非均匀两种分布形式施加在焊缝区,发现只有非均匀分布的固有剪切应变使焊接接头产生角变形.由此可知:角焊缝角变形产生的主要原因是在焊缝及其附近区域不均匀分布的固有剪切应变分量,而不是板厚方向上非均匀分布的横向固有正应变分量.此结论指出了关于焊接角变形产生机制的传统思维的认识误区,对研究预测角焊缝角变形简化方法具有指导意义. 相似文献
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随着航运市场对大吨位船舶需求的增大以及国际公约对新建船舶PSPC的严格要求,为了提高船舶建造效率与舱室密性质量,越来越多的国际一流造船企业纷纷在分段建造过程中采用角焊缝充气的工艺实施密性检验。介绍了角焊缝密性试验原理,分析了角焊缝密性试验的优点,指出了角焊缝密性试验弊端,同时提出了改进方法。 相似文献
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大型角焊缝焊接应力难以控制,特殊钢材的选用更加大了焊缝的裂纹倾向性。为防止焊缝裂纹的产生,实际焊接前,对角焊缝的应力进行了试验研究。本文介绍试验原理和方法,在试验的基础上,得到各材料参数用于有限元计算,又对焊接应力进行无损检测。检测结果与计算结果符合较好,说明材料参数比较准确,进而说明试验方法合理,结果可靠。 相似文献
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In support of the development of improved fillet weld sizing criteria for lightweight shipboard structures, a comprehensive static strength test program using longitudinal and transverse shear specimens according to AWS B4.0 Standards has been conducted. This test program covers base material with strength ranging from 71 ksi (490 MPa) to 96 ksi (660 MPa) and weld size ranging from 1/8″ (3 mm) to 3/8″ (10 mm). This paper focuses on a traction stress based analysis of the test data as an effort to establish a unified shear strength definition for load-carrying fillet weld specimens regardless of shear loading conditions. The proposed shear strength definition proves to be effective in correlating the fillet weld strength test data of the longitudinal and transverse shear specimens. The results of this investigation demonstrate that existing shear strength definitions used by various weld sizing criteria such as those given by Class Societies have two major limitations: (1) it cannot be related to a critical stress state on experimentally observed failure plane in transverse shear specimens; (2) it underestimates shear stress at failure due to severe stress concentration at weld end in typical longitudinal shear specimens. These two limitations have been shown to be the major cause for having two significantly different shear strength values: one is transverse shear strength obtained from transverse shear specimens and the other is longitudinal shear strength obtained from longitudinal shear specimens. 相似文献
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Stress concentration and residual stress have a significant influence on fatigue life of welded joints. In order to reduce the stress concentration of welded joints, a mathematical design method of tensile triangles (MTT) based on bionics was applied to weld shape design. Accordingly, the stress concentration of various weld beads in the corner boxing welded joint and the fillet welded T-joint was dissected using our in-house FEM software JWRIAN. It was found that there existed a large stress concentration in the conventional welded joints, whereas those welded joints with elongated weld bead were accompanied by a lower stress concentration, especially for elongated weld bead with MTT design. Furthermore, among the weld shapes of the corner boxing fillet welded joint, the rectangle shape of weld bead had the minimum stress concentration factor (1.05). For the fillet welded T-joint with MTT design, the stress concentration of weld toe decreased dramatically with the increase of the index of designed shape, but there was a minor difference of stress concentration at weld root between the weld beads with MTT design. In addition, application of low transformation temperature (LTT) weld metal utilizing martensitic transformation to the fillet welded T-joints can produce compressive residual stress at weld toe. 相似文献
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《船舶与海洋工程学报》2015,(3)
Submerged arc welding(SAW) is advantageous for joining high thickness materials in large structure due to high material deposition rate. The non-uniform heating and cooling generates the thermal stresses and subsequently the residual stresses and distortion. The longitudinal and transverse residual stresses and angular distortion are generally measured in large panel structure of submerged arc welded fillet joints. Hence, the objective of this present work is to quantify the amount of residual stress and distortion in and around the weld joint due to positioning of stiffeners tack. The tacking sequence influences the level of residual stress and proper controlling of tacking sequences is required to minimize the stress. In present study, an elasto-plastic material behavior is considered to develop the thermo mechanical model which predicts the residual stress and angular distortion with varying tacking sequences. The simulated result reveals that the tacking sequence heavily influences the residual stress and deformation pattern of the single sided fillet joint. The finite element based numerical model is calibrated by comparing the experimental data from published literature. Henceforth, the angular distortions are measured from an in-house developed experimental set-up. A fair agreement between the predicted and experimental results indicates the robustness of the developed numerical model. However, the most significant conclusion from present study states that tack weld position should be placed opposite to the fillet weld side to minimize the residual stress. 相似文献
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In load-carrying fillet welded connections, two fatigue failure modes are possible i.e. weld toe cracking and weld root cracking. The fatigue life associated with weld root cracking is typically much lower than weld toe cracking, exhibiting a wider scatter band, especially for welded aluminum alloys. This paper examines fatigue failure mode transition behaviors in load-carrying fillet welds made of aluminum and their governing parameters, among plate thickness, weld penetration, joint misalignment, weld material, and ultrasound impact peening(UIP). Through both experimental and theoretical studies, a quantitative fillet weld sizing criterion was proposed for avoiding weld root cracking in fillet-welded aluminum connections. 相似文献
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In a Thermal-Elastic-Plastic (TEP) FE analysis to investigate welding induced buckling of large thin plate welded structure such as ship panel, it will be extremely difficult to converge computation and obtain the results when the material and geometrical non-linear behaviors are both considered. In this study, an efficient FE computation which is an elastic FE analysis based on inherent deformation method, is proposed to predict welding induced buckling with employing large deformation theory, and an application in ship panel production is carried out. The proposed FE computation is implemented with two steps:(1) The typical weld joint (fillet weld) existing in considered ship panel structure is conducted with sequential welding using actual welding condition, and welding angular distortion after completely cooling down is measured. A TEP FE analysis with solid elements model is carried out to predict the welding angular distortion, which is validated by comparing with experimental results. Then, inherent deformations in this examined fillet welded joint are evaluated as a loading for the subsequent elastic FE analysis. Also, the simultaneous welding to assemble this fillet welded joint is numerically considered and its inherent deformations are evaluated.(2) To predict the welding induced buckling in the production of ship panel structure, a shell element model of considered ship panel is then employed for elastic FE analysis, in which inherent deformation evaluated beforehand is applied and large deformation is considered. The computed results obviously show welding induced buckling in the considered ship panel structure after welding. With its instability and difficulty for straightening, welding induced buckling prefers to be avoided whenever it is possible. 相似文献
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Submerged arc welding (SAW) is advantageous for joining high thickness materials in large structure due to high material deposition rate. The non-uniform heating and cooling generates the thermal stresses and subsequently the residual stresses and distortion. The longitudinal and transverse residual stresses and angular distortion are generally measured in large panel structure of submerged arc welded fillet joints. Hence, the objective of this present work is to quantify the amount of residual stress and distortion in and around the weld joint due to positioning of stiffeners tack. The tacking sequence influences the level of residual stress and proper controlling of tacking sequences is required to minimize the stress. In present study, an elasto-plastic material behavior is considered to develop the thermo mechanical model which predicts the residual stress and angular distortion with varying tacking sequences. The simulated result reveals that the tacking sequence heavily influences the residual stress and deformation pattern of the single sided fillet joint. The finite element based numerical model is calibrated by comparing the experimental data from published literature. Henceforth, the angular distortions are measured from an in-house developed experimental set-up. A fair agreement between the predicted and experimental results indicates the robustness of the developed numerical model. However, the most significant conclusion from present study states that tack weld position should be placed opposite to the fillet weld side to minimize the residual stress. 相似文献