verity焊接结构疲劳评估教程(II)_王悦东101-200

Typical Weld Representation Schemes for Using Shell/Plate Element Models
使用壳/平面单元模型的典型焊缝表达方式
Equivalent stiffness
等效刚度
Full penetration weld: two rows of plate elements with “triangle formation”
曲焊缝的“连续”焊缝定义
SS calculated long each weld line defined by average normal vectors at a node btw two adjacent elements
在相邻单元处，结构应力方向计算采用法线向 量平均值
A sharp angle of more than 45o may not produce a good mesh insensitivity in linear element models
优先选用连续的焊线定义
Discontinuous weld lines must be used in a model:
非连续的焊线定义应用在：
• Treated as separate weld line definitions
按分开的焊缝来处理的情况
• May show mesh-sensitivity in some cases, depending on load transfer
整条焊缝上“能量守恒”
• Traction continuity requirements at nodes along a weld line
在焊缝各节点处拉力连续
Generalized Procedures for Shell/Plate Element Models – Open Weld Ends
如果两单元法线向量夹角大于45度，会导致线性 单元网格不敏感的特性有所降低
管接头封闭焊缝
A Wrap-Around Weld End – “Continuous”
环绕焊缝末端－“连续”
Weld Line Definition Example
焊缝定义示例
Continuous weld lines always preferred
crack) 为“边缘细节”定义的焊缝（面内裂纹） • SS calculation using “virtual node method” “虚拟节点法”的结构应力计算
壳/平面单元模型的通用求解过程-非闭合焊缝
1. Collect force/moments wrt x-y-z
在全局坐标系下计算节点力及弯矩
2. Definite local coordinate system along weld line: x’-y’-z’
沿焊线定义局部坐标系：Ｘ`-Ｙ`-Ｚ`
The SS Method Must Accommodate the Following Practical Considerations
结构应力法必须适应下列实际因素
Arbitrary mesh designs:
任意网格设计
• Distorted mesh
变形的网格
• Mismatched element
面外（沿厚度方向的缺口效应） • Equilibrium conditions enforced wrt to t 平衡条件严格依赖于t
In-plane notch effects
面内缺口效应 • Open-ended weld line with weld ends subjected to
high stress concentration regime 末端承受高应力集中的非封闭焊缝 • Using over-simplified weld representation 使用过简化的焊缝的表示 • “Weld line definitions” for “Edge Detail” (in-plane
不匹配的网格
• Triangle elements
三角形网格
• Continuously curved weld line in 3D space
三维连续曲焊缝
Line force/moment formulation strategy:
线载荷/弯矩公式 • “Work-equivalent” with respect to an entire weld line
3. Rotate nodal forces/moments
转换节点力及弯矩
4. Solving simultaneous equations
求解方程
Through-Thickness Traction
Conditions Using Nodal Forces
用节点力作为厚度方向上的拉伸条件
对于闭合焊缝：
在某些网格敏感度较高的情况，这与载荷传递 模式有关
Continuous Weld Line around Corner –
Structural Stress Results (Linear Elements)
拐角处连续焊线－结构应力结果（线性单元）
来自百度文库
Continuous Weld Line Corner – Structural
Stress Results (Parabolic Elements)
拐角处连续焊线－结构应力结果（二阶单元）
Out-of-Plane versus In-Plane Notch Effects in
Structural Stress Calculation
结构应力计算中面内及面外的缺口效应对比
Out-of-plane (through-thickness notch effects
全熔透：用两排三角形平面单元
Partial penetration: one row of inclined elements
部分熔透：用一排倾斜的单元
A Lap Fillet Weld
搭接焊
A Padding Plate Fillet Joint
垫板焊接接头（？？？）
“Continuous” Weld Line Definition for Curved Weld Lines