Computational weld mechanics

计算焊接力学

• 批准号: 2922-2007
• 负责人: Goldak, John
• 金额: $ 1.6万
• 依托单位: Carleton University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2008
• 资助国家: 加拿大
• 起止时间: 2008-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=388676
• 关键词: Computational; weld; mechanics

The proposed research is to solve for the design of welded structures, i.e., we no longer assume the design is given. Instead we assume that we are given in-service loads and a preliminary design with no weld joints specified. The analysis should predict the optimum position and size of all weld joints, weld procedures, weld schedules, fixture design and fixture schedule. For an important class of welded structures, the primary failure mode is fatigue. Given CAD files for the geometry of the parts for a structure such as a large tractor, the material type for each part and the associated in-service loads, we propose the following strategy: Mesh all parts automatically. Then the user applies in-service loads and constraints. Then with constraints between adjacent parts applied automatically perform a linear static (or dynamic) 3D FEM analysis. Also potential weld paths are identified automatically by adjacency between parts. From the constraint force per unit length along each potential weld path, a trial weld size and weld procedure will be computed. Next the structure is remeshed to include the proposed weld joints with filler metal. Then a thermal stress analysis of the weld joints in the welded structure is done to compute the transient temperatures, microstructure evolution, residual stress and distortion due to welding. The weld pool size and shape will be computed using an Ohji-Sudnik weld pool model. Microstructure evolution will be modelled using Monte Carlo algorithms and computational thermodynamics. The stress analysis will include single crystal thermo-visco-plastic analysis of the evolving microstructure. Then either a linear or a non-linear plastic FEM analysis with constraints is redone with the new weld joints. In these weld joints, the 3D stress distribution due to in-service loads and residual stress in the weld joints and particularly in high risk features such as the weld toe are computed. From the stress distribution and in-service load cycles, the fatigue life of the weld is estimated. If the fatigue life is too long, the weld size can be reduced. If the fatigue life is too short, the weld must be strengthened or redesigned. This process will be done automatically.

所提出的研究是为了解决焊接结构的设计，即，我们不再假设设计是给定的。相反，我们假设我们给出了在役载荷和未指定焊接接头的初步设计。分析应预测所有焊接接头的最佳位置和尺寸、焊接程序、焊接进度、夹具设计和夹具进度。 对于一类重要的焊接结构，其主要失效模式是疲劳。 给定结构（如大型拖拉机）零件几何形状的CAD文件、每个零件的材料类型和相关的使用载荷，我们提出以下策略：自动网格化所有零件。然后，用户应用使用中的载荷和约束。然后，在相邻零件之间应用约束，自动执行线性静态（或动态）3D FEM分析。 此外，潜在的焊接路径被自动识别的零件之间的邻接。 根据沿每个潜在焊接路径的每单位长度沿着的约束力，将计算试验焊接尺寸和焊接程序。 接下来，对结构进行重新网格化，以包括建议的带有填充金属的焊接接头。 然后对焊接结构中的焊接接头进行热应力分析，计算焊接引起的瞬态温度、组织演变、残余应力和变形。 将使用Ohji-Sudnik焊池模型计算焊池尺寸和形状。微观结构的演变将使用蒙特卡罗算法和计算热力学建模。应力分析将包括演变微观结构的单晶热粘塑性分析。 然后，对新的焊接接头重新进行带约束的线性或非线性塑性有限元分析。 在这些焊接接头中，计算了由于焊接接头中的使用载荷和残余应力而引起的3D应力分布，特别是在诸如焊趾的高风险特征中。 从应力分布和在役载荷循环，焊缝的疲劳寿命估计。如果疲劳寿命太长，可以减小焊缝尺寸。如果疲劳寿命太短，则必须对焊缝进行强化或重新设计。此过程将自动完成。