焊接结构疲劳评估教程(II)_王悦东-100
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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
在某些网格敏感度较高的情况，这与载荷传递 模式有关
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
ISSC舱底关节连接试验（ Wang et al, 2004）
Structural Stress Calculation Results
结构应力法计算结果
Applications of the Structural Stress Method in Multi-Axial Fatigue
结构应力法在多轴疲劳中的应用
Quality data are scarce
缺乏良好的数据
Some well-known multi-axial fatigue data: EPRI, LBF,TWI, UIUC
一些著名的多轴疲劳数据： EPRI, LBF,TWI, UIUC Observations: 总结：
• Crack tends to propagates along weld toe into plate at least for the most part of life time
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 local coordinate system along weld line: x’-y’-z’
在全局坐标系下计算节点力及弯矩
2. Definite 3. Rotate
沿焊线定义局部坐标系：Ｘ`-Ｙ`-Ｚ`
Examples with Open-Ended Weld Line: With and Without In-Plane Notch Effects
非封闭焊缝示例：考虑及不考虑平面内缺口效应
Small Edge Detail Test Specimens: In-Plane Notch Effects in SS Calculation
Comparison of VNM and Results Using Refined Weld Representation Schemes
虚拟节点法与细化网格方法对比
A Box Fillet Weld Example –Weld Toe on Attachment Plate
方角焊缝例子－附加板上的焊趾 W/O Weld Representation 没有添加焊缝单元
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
A Box Fillet Weld Example – Weld Toe on Attachment Plate
方角焊缝例子－附加板上的焊趾
W/ Weld Representation 添加焊缝单元
Intermittent Welds
间断焊缝
Shell versus 3D Solid Models
ISSC Longitudinal Frame/Connection Tests Analyzed by ABS (Wang et al, 2004)
ISSC纵向架构连接试验（ Wang et al, 2004）
ISSC Bilge Knuckle Test Analyzed by ABS (Wang et al, 2004)
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
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
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）
Continuous Weld Line Corner – Structural Stress Results (Parabolic Elements)
如果l1< l/2会获得较好的网格不敏感特性
l1: 在l范围内面内最终裂纹失效长度
Single Element Based SS Calculation Using VNM - An Over-Simplified Plate Element Model
基于单个单元的使用虚拟节点法的结构应力计算 －过简化的平面单元模型
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
nodal forces/moments
simultaneous equations
转换节点力及弯矩
4. Solving
求解方程源自文库
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：
Typical Weld Representation Schemes for Using Shell/Plate Element Models
壳单元与3D单元模型对比
SS Results versus Software Packages
结构应力结果与 商用软件结果对比
An Independent Evaluation of The SS and HSS Method at Rat Hole End (B. Healy, 04)
结构应力法与热点应力法评估 鼠洞结构（B. Healy, 04 ）的结果
沿Ｗ或预期的断裂路径定义“焊线”
Failure criterion: l1 << w
Stresses along “weld line” are not statically determined Load: Virtual Node Method
沿着“焊线”的应力不由静态的载荷决定： 虚拟节点法
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
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
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
Virtual Node Method (VNM) for Structural Stress Calculations in Structural Components
结构构件中计算结构应力的虚拟节点法
Large w or not well-defined
Ｗ较大或不容易确定
“Weld line” defined along w or an anticipated failure path
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”
全熔透：用两排三角形平面单元
Partial
penetration: one row of inclined elements
破坏准则：剩余宽度(w)全部断开 In-plane notch effects are 面内缺口效应的确定，通过：
• te=w in structural stress calculations
结构应力计算中：te=w
• For symmetric edge detail te=w/2
对于对称结构： te=w/2
小边缘细节试验试样：结构应力 计算中面内缺口效应
Small w
Ｗ较小 Nominal
stress w.r.t. w is well
Defined
依据Ｗ的名义应力容易确定
Failure
criterion: full ligament (w) separation captured by
至少在大部分使用期限内，裂纹倾向沿焊趾向板内扩展
• Based “nominal stress range”:
基于名义应力幅值
– Torsion is more damaging than bending
扭转的破坏强于弯曲的破坏
– Out-of-phase is more damaging than in-phase loading
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 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
失效准则： l1 << w
• Equilibrium conditions enforced within a reference distance l (Position 2)
平衡条件限定在参考距离l内（２号点位置）
• l1: final in-plane crack length at failure within l • Good mesh-insensitivity for l1< l/2
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
优先选用连续的焊线定义
Discontinuous weld lines must be used in a model:
异步载荷破坏强于同步载荷
• 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
在某些网格敏感度较高的情况，这与载荷传递 模式有关
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
ISSC舱底关节连接试验（ Wang et al, 2004）
Structural Stress Calculation Results
结构应力法计算结果
Applications of the Structural Stress Method in Multi-Axial Fatigue
结构应力法在多轴疲劳中的应用
Quality data are scarce
缺乏良好的数据
Some well-known multi-axial fatigue data: EPRI, LBF,TWI, UIUC
一些著名的多轴疲劳数据： EPRI, LBF,TWI, UIUC Observations: 总结：
• Crack tends to propagates along weld toe into plate at least for the most part of life time
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 local coordinate system along weld line: x’-y’-z’
在全局坐标系下计算节点力及弯矩
2. Definite 3. Rotate
沿焊线定义局部坐标系：Ｘ`-Ｙ`-Ｚ`
Examples with Open-Ended Weld Line: With and Without In-Plane Notch Effects
非封闭焊缝示例：考虑及不考虑平面内缺口效应
Small Edge Detail Test Specimens: In-Plane Notch Effects in SS Calculation
Comparison of VNM and Results Using Refined Weld Representation Schemes
虚拟节点法与细化网格方法对比
A Box Fillet Weld Example –Weld Toe on Attachment Plate
方角焊缝例子－附加板上的焊趾 W/O Weld Representation 没有添加焊缝单元
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
A Box Fillet Weld Example – Weld Toe on Attachment Plate
方角焊缝例子－附加板上的焊趾
W/ Weld Representation 添加焊缝单元
Intermittent Welds
间断焊缝
Shell versus 3D Solid Models
ISSC Longitudinal Frame/Connection Tests Analyzed by ABS (Wang et al, 2004)
ISSC纵向架构连接试验（ Wang et al, 2004）
ISSC Bilge Knuckle Test Analyzed by ABS (Wang et al, 2004)
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
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
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）
Continuous Weld Line Corner – Structural Stress Results (Parabolic Elements)
如果l1< l/2会获得较好的网格不敏感特性
l1: 在l范围内面内最终裂纹失效长度
Single Element Based SS Calculation Using VNM - An Over-Simplified Plate Element Model
基于单个单元的使用虚拟节点法的结构应力计算 －过简化的平面单元模型
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
nodal forces/moments
simultaneous equations
转换节点力及弯矩
4. Solving
求解方程源自文库
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：
Typical Weld Representation Schemes for Using Shell/Plate Element Models
壳单元与3D单元模型对比
SS Results versus Software Packages
结构应力结果与 商用软件结果对比
An Independent Evaluation of The SS and HSS Method at Rat Hole End (B. Healy, 04)
结构应力法与热点应力法评估 鼠洞结构（B. Healy, 04 ）的结果
沿Ｗ或预期的断裂路径定义“焊线”
Failure criterion: l1 << w
Stresses along “weld line” are not statically determined Load: Virtual Node Method
沿着“焊线”的应力不由静态的载荷决定： 虚拟节点法
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
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
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
Virtual Node Method (VNM) for Structural Stress Calculations in Structural Components
结构构件中计算结构应力的虚拟节点法
Large w or not well-defined
Ｗ较大或不容易确定
“Weld line” defined along w or an anticipated failure path
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”
全熔透：用两排三角形平面单元
Partial
penetration: one row of inclined elements
破坏准则：剩余宽度(w)全部断开 In-plane notch effects are 面内缺口效应的确定，通过：
• te=w in structural stress calculations
结构应力计算中：te=w
• For symmetric edge detail te=w/2
对于对称结构： te=w/2
小边缘细节试验试样：结构应力 计算中面内缺口效应
Small w
Ｗ较小 Nominal
stress w.r.t. w is well
Defined
依据Ｗ的名义应力容易确定
Failure
criterion: full ligament (w) separation captured by
至少在大部分使用期限内，裂纹倾向沿焊趾向板内扩展
• Based “nominal stress range”:
基于名义应力幅值
– Torsion is more damaging than bending
扭转的破坏强于弯曲的破坏
– Out-of-phase is more damaging than in-phase loading
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 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
失效准则： l1 << w
• Equilibrium conditions enforced within a reference distance l (Position 2)
平衡条件限定在参考距离l内（２号点位置）
• l1: final in-plane crack length at failure within l • Good mesh-insensitivity for l1< l/2
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
优先选用连续的焊线定义
Discontinuous weld lines must be used in a model:
异步载荷破坏强于同步载荷