共查询到17条相似文献,搜索用时 187 毫秒
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将焊接试验与数值模拟相结合,对采用压条拘束控制的2种典型焊接接头失稳变形机理进行了研究。基于热-弹-塑性有限元方法,分别再现5mm厚对接接头和T型接头在常规自由态和压条拘束下的焊接过程,将2种接头计算得到的面外变形与焊接试验后测量的面外变形进行对比,从而验证所采用的有限元计算方法的准确性。分别计算对接接头与T型接头在不同压条拘束距离下的面外变形,并分析拘束距离对2种接头焊接失稳变形的控制效果;比较不同拘束距离下接头的焊接温度场及固有变形,阐明压条拘束控制2种焊接接头失稳变形的机理。结果表明:施加压条拘束使对接接头的纵向固有收缩和横向固有弯曲均减小,从而控制其焊接失稳变形;T型接头施加压条拘束后,几乎不影响纵向固有收缩,但使得横向固有弯曲显著减小,从而达到控制焊接失稳变形的效果。 相似文献
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预测船体复杂结构的焊接变形对制造工艺设计和精度控制具有重要的工程价值.基于固有应变理论,利用船体结构焊接变形预测专用软件Weld-sta对多用途船双层底结构焊接变形进行了预测,发现船长方向收缩最大变形量为13.2mm,船宽方向最大变形量14.5 mm.通过数值模拟结果与实验实测值的对比,可以得到软件计算的精度超过80%,验证了固有应变理论及软件用于焊接变形预测的可靠性,并在此基础上针对船体总段船台合拢的焊接变形进行了预测,发现焊接总收缩变形量为50.339 mm,与实际加工经验基本吻合.根据此结论可以针对各船体总段预留合理的焊接变形收缩量,验证了固有应变为基础的弹性板单元有限元预测法在船体总段合拢焊接中应用的可行性. 相似文献
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水密横舱壁作为20000TEU集装箱船的关键结构,对尺寸精度的要求十分严苛,而焊接变形严重影响其建造精度。针对这一问题,采用基于固有变形理论的弹性有限元分析,来预测水密横舱壁结构的面外焊接变形。比较了计算固有变形的两种方法的准确度,并且总结了热输入与固有变形各分量的经验公式,还提出了减小面外焊接变形的措施。结果表明,通过与实测数据对比验证了弹性有限元分析可快速、准确地预测水密横舱壁结构的面外焊接变形;对于对接接头,变形反演法比应变积分法得到的横向固有弯曲更准确;热输入与固有变形各分量呈线性递增关系;将整个水密横舱壁结构由原来的3段分成5段,并采用对称焊接顺序,面外焊接变形最小,同时会降低对船厂吊装能力的要求。 相似文献
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水密横舱壁作为20000TEU集装箱船的关键结构,对尺寸精度的要求十分严苛,尤其是焊接变形严重影响其建造精度。针对这一问题,采用基于固有变形理论的弹性有限元分析,来预测水密横舱壁结构的面外焊接变形。同时,比较了计算固有变形的两种方法的准确度,并且总结了热输入与固有变形各分量的经验公式,还提出了减小面外焊接变形的措施。结果表明,通过与实测数据对比验证了弹性有限元分析可快速、准确地预测水密横舱壁结构的面外焊接变形;对于对接接头,变形反演法比应变积分法得到的横向固有弯曲更准确;热输入与固有变形各分量呈线性递增关系;将整个水密横舱壁结构由原来的3段分成5段,并采用对称焊接顺序,面外焊接变形最小,同时会降低对船厂吊装能力的要求。 相似文献
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采用基于固有应变法的弹性有限元分析预测大型复杂结构的焊接变形的前提是必须已知焊缝附近的固有变形。结构的焊接残余应力与焊接变形取决于其接头的固有变形大小及分布,因此开发精确计算接头固有变形的方法,并依此建立一个完善的固有变形数据库对于大型复杂结构焊接变形的预测有重要意义。文中提出了几种计算固有变形的方法包括公式法、热弹塑性有限元法、实测法,并分别采用这几种方法对典型T型接头的横向固有收缩与纵向固有收缩进行计算,三种方法得到的结果比较一致。在此基础上,进一步以典型船体结构为研究对象,采用依照这三种方法建立的固有变形数据库对其焊接变形进行预测,并与实测数据进行比较,验证了该数据库的有效性。 相似文献
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As an application to predict and mitigate the out-of-plane welding distortion by elastic FE analysis based on the inherent deformation theory, a panel structure of a pure car carrier ship is considered. The inherent deformations of different types of welded joints included in this ship panel structure are evaluated beforehand using thermal elastic plastic FE analysis. Applying idealized boundary condition to focus on the local deformation, elastic FE analysis shows that the considered ship panel structure will buckle near the edge and only bending distortion is dominant in the internal region. In order to mitigate out-of-plane welding distortion such as buckling and bending, straightening using line heating is employed. In the internal region, only inherent bending with the same magnitude as welding induced inherent bending is applied on the opposite side of welded joints (fast moving torch). On the other hand, only in-plane inherent strain produced by line heating is introduced to the edge region to correct buckling distortion (slow moving torch). The magnitude of out-of-plane welding distortion in this ship panel structure can be minimized to an accepted level. 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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在进行大型结构焊接变形有限元分析时,为了固定整体结构刚体位移必须施加不少于6个自由度的约束,但对于自由状态下的结构而言,如何施加这6个最少约束是非常的困难,长期以来是困扰研究人员的难题,也是焊接结构有限元分析在工业现场应用的一个瓶颈。所谓惯性释放法就是可以在不加约束的情况下模拟自由结构的变形。该文将在航海航空领域得到广泛应用的惯性释放法引入大型焊接结构变形分析,解决了自由状态下结构必须施加约束的问题。首先以典型的对接接头为例,比较了两种不同的约束方法之间的差别。然后通过一个典型的船体焊接变形预测的实例,验证了惯性释放法在大型结构中应用的可行性,为焊接结构变形分析在工业生产中广泛应用提供了一个有效的方法。 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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Out-of-plane welding distortions of block structures during fabrication of offshore structure will significantly influence its dimensional accuracy and production schedule. Taking a B514 block of a semi-submersible lifting and disassembly platform as research object, typical welded joints and their welding conditions were summarized based on actual welding procedure specification (WPS). Effective thermal elastic plastic (TEP) finite element (FE) analysis with parallel computation technology was carried out to examine thermal-mechanical response. Welding inherent deformations, which are considered as the elementary cause of welding distortion, were then evaluated. With welding inherent deformations as mechanical loading, elastic finite element (FE) analysis was then employed to predict dimensional accuracy of examined B514 block, which has a good agreement with measurement data. In order to ensure the fabrication accuracy with less out-of-plane welding distortion, inverse deformation approach was applied to reduce the out-of-plane welding distortion, and influence of welding sequence on out-of-plane welding distortion was also examined. Both mitigation practices have obvious effect on dimensional accuracy of examined B514 block, while corresponding mechanical mechanisms were also clarified. 相似文献