焊接结构疲劳评估教程课件.ppt

1、202K.Frank在UTA所做实验(2004)在UTC/UMR 所做实验(2003)DOT资助的信号灯支架实体实验DOT Recently Funded Full Scale Tests Signal Mast ArmTests by K.Frank at UTA(04)Tests at UTC/UMR(03)203实体刚度测试(Frank,2004)Full Scale Stiffener Tests(Frank,04)204实体大梁的四点弯曲测试（Fisher）Without Cover Plate无盖板测试无盖板测试With Cover Plate带焊接盖板测试带焊接盖板测试Fishe

2、rs Tests on Full Scale Girders with and without Cover Plate205基于结构应力的相关性测试(Fisher,1971)Structural Stress Based Correlation Fishers Full Scale Tests(1971)206DOT实体测试汇总All Full Scale DOT Tests207How About Correlation with the Master S-N Curve?与主 S-N曲线的相关性如何？主S-N曲线：标准方差 0.25Master S-N Curve:Std Deviatio

3、n:0.25208焊态、UIT数据(Frank,2003-2004)与主S-N 曲线As-Welded versus UIT Treated Data(Frank,03-04)Plotted Against the Master S-N Curve209Test Data Analysis of Tubular K joints-UKOSRP IIK型管接头测试数据分析UKOSRP II 210管接头测试数据(UKOSRP II)与JIP主S-N曲线的关系主S-N曲线(2005)Tubular Joint Test Data(UKOSRP II)and Correlation with JIP

4、 Master S-N CurveLines:Master S-N(2005)211铝合金MIG焊缝(Ford提供数据)40Conventional Method:Nominal Stress Parameter传统方法：名义应力参数Battelle Method:Structural Stress ParameterBattelle方法：结构应力参数Aluminum Alloy MIG Welds(Courtesy of Ford)212铝合金激光焊的主S-N曲线(Ford提供数据)Master S-N Curve for Aluminum Alloy Laser Welds(Courtes

5、y of Ford)213基于断裂力学和S-N曲线进行疲劳寿命评估的等效性Equivalence between Fracture Mechanics and S-N Curve Based Fatigue Assessmentsn For all the data processed,the following can be concluded 由处理得到的数据结果，可以得到如下结论：Parameters C and m(crack growth rate data)uniquely determine S-N behavior 参数C和m(裂纹生长率数据)可唯一确定S-N曲线 n Life

6、 Prediction can be done with either(1)or(2)由式(1)或(2)进行寿命预测：Weld quality(i.e.,af)effects 焊接质量(af)的影响 Total life 总寿命 Remaining life prediction 剩余寿命预测214初始裂纹尺寸对寿命的影响Initial“Crack”Size Effects on Life Integraln I(r,ai/t,af/t)：Quantify weld quality effects(ai/t)on fatigue trength 量化焊缝质量(ai/t)对疲劳强度的影响 Rem

7、aining life assessment for given ai/t and af/t FFS 对给定的ai/t 和af/t进行剩余寿命评估-FFS Why not directly using fracture mechanics then 为什么不直接使用断裂力学方法进行分析 -K solutions availability for complex joint types 能否得到复杂接头的K解 -Material data availability 能否得到材料数据 Comprehensive Ss-N data can be used here 这里所能使用的可理解的Ss-N

8、数据215总 结Concluding Remarksn Fracture mechanics applications of the structural stress method 结构应力法中的断裂力学 Effective engineering estimation of K in complex joints 有效估算工程中复杂接头的K值 Unified crack growth model:two stage crack growth model 统一的裂纹扩展模型：两阶段模型n The structural stress based Master S-N curve provide

9、 a single parameter description of:基于结构应力的主S-N曲线提供了单参数描述方法：Thickness(t)厚度(t)Loading Mode(r)载荷模式(r)Stress concentration()应力集中()n Validated by correlating S-N data of over 5000 fatigue tests 超过5000次测试数据验证S-N曲线的正确性n The method also offers an effective alternative method for remaining life or FFS assess

10、ment 该方法还对剩余寿命或FFS评估提供了一个有效的替代方法216Structural Stress Modeling Procedure and Life Prediction结构应力建模过程与寿命预测 n Structural stress modeling and life prediction procedures dos and donts 结构应力建模与寿命预测须知 Failure definition 失效定义 Weld line definition 焊线定义 Weld line curvature considerations 焊线曲率因素 Weld representa

11、tion considerations 焊线表示方法的考虑 Load controlled versus displacement controlled(load shielding)conditions 载荷控制与位移控制(负载屏蔽)条件n Implications on fatigue testing procedures 疲劳测试程序的影响因素 Failure definition and monitoring 失效的定义与监测 Simple specimens versus component testing 简单样本与组件测试 n Life prediction examples 寿

12、命预测例子 SAE FD&E“WELD CHALLENGE”problem -SAE“焊接疲劳挑战”中的疲劳问题 Yagis tests -Yagi测试 Analysis of ISSC full scale component tests -ISSC组件实体测试 A recent full scale ASME Div 2 vessel tests -ASME标准中压力容器测试 MIG and welded component tests aluminum alloys -铝合金MIG焊接组件测试217基于结构应力的寿命预测程序SS Based Life Prediction Procedu

13、re n Structural stress modeling and life prediction procedures dos and donts 结构应力建模与寿命预测须知 Failure definition 失效定义 Weld line definition 焊线定义 Weld line curvature considerations 焊线曲率因素 Weld representation considerations 焊线描述差异的影响 Load controlled versus displacement controlled(load shielding)conditions

14、 载荷控制与位移控制(负载屏蔽)条件218失效定义Failure Definition n Fatigue crack 疲劳裂纹 Penetrating thickness t depth 穿透厚度t Extending along weld line in the order of 1-2 t in length 焊线上沿长度方向扩展(1-2t)Edge details 边界细节 Small specimens t=w 小样本：t=w Components or large specimens l1=t 组件或大样本：l1=t -Used in all test data correlati

15、on 在所有相关测试数据中使用 -Smaller than t:random behavior dominates 小于t：主要是随机行为219“Hot Spot”Definitions in HSS Stress Methods versus“Weld Line”Definitions in SS Method热点应力法中“热点”的定义与结构应力法中“焊线”的定义 Types“a)”-”c)”热点a、b、c Extrapolation procedures 外推程序 S-N curve selection 选取S-N曲线 Weld Lines 1 and 2 焊线1、2 Solve simu

16、ltaneous equations for each 同时求解方程 Same master S-N curve 使用同一条S-N曲线Weld Line 2:When using shell/plate elements,through-thickness bending is ignored 焊线2：当使用板壳单元时，忽略厚度方向的弯曲应力220焊缝表现形式不同造成的影响Effects of Weld Representation on Weld Line DefinitionWeld Line 1:approximated by Weld Line 2 焊线1被焊线2近似替代Both we

17、ld lines are represented 两条焊线同时存在 OK for Weld Line 2(toe failure into attachment plate)焊线2没问题(附加板焊趾失效)Mesh-sensitivity develops for modeling weld toe failure into flange 边缘上焊趾失效时，模型网格敏感性提高 Not good for loading in x x方向载荷不合适 Good for both weld lines when using coarse mesh(1t or above)即便使用粗网格，两焊线模型也能取

18、得较好结果(=1t)Weld Line 1:two weld lines should be considered for finer mesh 焊线1：两焊线网格都应考虑加密221Weld Line Definitions for Edge Details:Small Lab Specimens versus Structural Joints描述边界细节的焊线定义中：实验室小样本与结构接头222Weld Line Curvature Considerations焊线曲率的影响223Weld Toe Failure Mode vs Weld Representation焊趾失效模式与焊缝表现

19、形式Structural Joint结构节点Weld Toe Failure:SS are the same for Models A and B焊趾失效：模式A与B结构应力相等224A Simple Shear Correction Scheme for Models W/O Representing Weld:A Tubular T Joint无焊缝单元T型连接管的简化剪切修正方案225Fillet Weld Representations:Small Fillets or between Drastically Different Thicknesses角焊表示方法：小圆角或厚度突变So

20、lid model should be used to calibrate shell/plate models实体模型应该用于校验壳/板模型226Load-Controlled versus Displacement-Controlled Conditions载荷控制条件与位移控制条件Failure criterion:Through-thickness failure 失效准则：厚度贯穿失效227S-N Data from TestsS-N曲线测试数据n Most lab test data are collected under load controlled conditions 大部

21、分测试数据都是在载荷控制条件下得到的n Component test data:load shielding(or locally displacement-controlled)often exists 组件测试数据：一般存在负载屏蔽或局部位移控制 e.g.,Multiple cracking due to load path change 例如，由于加载路径的改变引起的多裂纹开裂 Consistent data can only be obtained with stringent monitoring schemes before load path change occurs 只有加载

22、路径改变之前采用更严格的监控方案，才能得到协调的数据 Actual displacement-controlled conditions are difficult to estimate 实际上，位移控制条件是很难估计的n For life estimation purpose,load-controlled conditions should be used to be on the conservative side 对于寿命估算，保守做法是使用载荷控制228Implications on Fatigue Test Procedures 疲劳试验过程的影响因素n Specimen des

23、ign,sizing,and loading mode 样品设计、尺寸、加载模式n Failure definition and monitoring procedures 失效定义与检测程序n Documentation 文档文件229Failure Criteria for Fatigue Evaluation Using Master S-N Curve and Testing利用主S-N曲线进行疲劳评估的失效准则及其测试n Through-thickness failure and load controlled conditions 厚度贯穿失效与载荷控制条件 “Leakage”渗透

24、法 Before any significant load drop(10%?)载荷明显下降之前 Before multiple cracks develop 多裂纹形成之前 Tension tests less sensitive to above 拉力测试对以上各项不敏感230Stiffness/Compliance Monitoring and Final Failure Determination MIG Weld Example刚度柔度监测与最终失效认定MIG焊缝为例231Specimen Designs and Loading Modes样本设计与载荷模式n Use simple

25、geometry and loading mode for easy interpretation 尽量使用简单几何形状和载荷模式n Target weld toe failure modes(i.e.,sheet failure at weld)目标焊趾失效模式(即薄板焊接失效)n Sufficient width to fully contain weld residual stress effects(w/t6)足够的宽度以充分考虑焊缝残余应力的影响(w/t6)232Data Documentation/Reporting数据文档/报告n Load life data 载荷寿命数据n P

26、eak load and peak displacements at fixed interval 固定时间间隔的峰值载荷与峰值位移n Individual specimen geometry measurements before testing 试验前单独测量样本几何尺寸n Grip position measurements 夹持位置测量n Photographs showing failure position and path with respect to weld position 显示焊缝位置的失效部位与路径的图片n Any anomalies 其他任何异常情况233Impor

27、tance of Grip Positions Unsymmetric Specimens夹持位置的重要性非对称样本234Fatigue Life Evaluation Procedures Using the Structural Stress Method-Shell/Plate Models结构应力法评估疲劳寿命过程壳/板模型n Construct a FE model 创建有限元模型n Define weld lines(nodal numbers/weld toe or throat element numbers)定义焊线(节点号/焊趾或焊喉的单元号)Automated searc

28、h among all possible weld lines 自动搜索所有可能的焊线 Select a few known critical ones 选择若干关键焊线n Run FE analysis requesting nodal forces/moments 进行有限元分析，提取节点力与弯矩n Post-processing for structural stresses 对结构应力进行后处理 Manual calculations for a few hot spots,or 手动计算几个热点，或者 Automated calculations using SS post-proc

29、essors 利用结构应力处理程序自动计算n Life estimation:寿命评估 Constant amplitude loading:go directly to the master S-N curve 常幅载荷：直接使用主S-N曲线 Variable amplitude loading:cycle counting as usual,and damage summation per master S-N curve 变幅载荷：循环计数、主S-N曲线下的损伤累计235Fatigue Evaluation Example 1:Yagis Tests疲劳评估算例1Yagi试验n Docu

30、mented in SR202 of Shipbuilding Research Association of Japan(1991)日本造船联合会文件资料SR202(1991)n Constant amplitude loading 常幅载荷n Load controlled conditions 载荷控制条件n Through-thickness failure 贯穿厚度失效n Photographs showing failure position and path with respect to weld position 显示焊缝位置的失效部位与路径的图片n Used in Batt

31、elle JIP for correlation with HHI hopper corner test data Battelle JIP使用的HHI测试数据236Finite Element Modeling and Structural Stress Analysis有限元建模与结构应力分析n Shell element model 壳单元模型n Weld represented with 45 degree inclined elements 焊缝表示为45度倾斜单元n Define weld line(nodes)定义焊线(节点)n Define weld elements(Shad

32、ed)定义焊接单元(阴影部分)n Calculation SS(s)along the weld toe under unit load 沿焊趾计算单位载荷下的结构应力n Determine peak s 确定最大应力变化范围s237Correlate Yagis Test Results with Master S-N Data主S-N曲线与Yagi试验数据n Calculate equivalent structural stress range for each test 计算等效结构应力变化范围n Plot Yagis test results in terms of Ss-N S-N

33、曲线与Yagi试验结果238Component Validation Tests组件有效性测试239Component Test Results versus S-N Data from Small Specimens组件测试结果与来自于小样本的S-N数据2402003 SAE FD&E“Fatigue Challenge”Blind Life Prediction2003 SAE FD&E“疲劳挑战”寿命盲测n SAE FD&E issued a“fatigue prediction challenge”SAE FD&E发出了“疲劳预测挑战”n Actual test results wer

34、e given after all participants presented their predicted lives 试验结果将在所有参赛者提交疲劳寿命预测报告之后公布n See www.fatigue.org/weld 详见：www.fatigue.org/weld n Define weld elements(Shaded)定义焊接单元(阴影部分)n The structural stress method won“The Best Prediction”结构应力法最终获胜，赢得了“最佳预测”奖241Mesh-Insensitivity Demonstration The Stru

35、ctural Stress Method网格不敏感示例结构应力法242Comparison of Predicted and Actual Test Results预测结果与实际试验结果相比较243A 2nd SAE Weld Challenge:Variable Amplitude Loading SAE第二届焊接挑战：变幅载荷n Overall specimen geometry:same as before(Challenge 1)所有测试样本与上届保持一样n Weld end is much bigger in Challenge 2A (postings at www.fatigue

36、.org/weld)焊缝端部增大很多，详见www.fatigue.org/weld 244FE Models:SAE Weld Challenge 2A versus First(Challenge 1)有限元模型：与第一届挑战模型相对比245Identification of Critical Locations after Searching Two Weld Toe Lines 寻找两条焊趾线，确定危险位置Actual failure location:Weld end 实际失效位置：焊端Observations:小结 If the weld ends are big(modeled a

37、s posted in the website),weld end failure occurs on 4”x4”对大焊端建模，失效网格为4 4 。(见网站模型图)if the weld ends are as small as those for Challenge 1,failure occurs at 2”X6”weld toe corner 对小焊端建模，失效网格为2 6 。(第一届挑战模型)246Two Variable Amplitude Loading Cases Tested and Predicted Mean Lives两个不同载荷幅度工况试验与平均寿命预测1.19.2 t

38、imes the grapple skidder torque history(GSTH)2.27.1 times the grapple skidder torque history抓举卷扬机 19.2倍、27.1倍的扭矩历史247Test Results:Failure Locations试验结果：失效位置248Additional Applications of the Structural Stress Method 结构应力法的其他应用n Treatment of weld root/throat cracking 焊根/焊喉裂缝的处理n Treatment of multi-axi

39、al fatigue 多轴疲劳的处理n Treatment of thermal loading 温度载荷的处理n Treatment of high-mean loading 高平均载荷的处理n Solder fatigue in electronic packaging 电子封装中的焊料疲劳249Evaluation of Potential Failure Modes as a Function of Weld Size焊缝尺寸相关的潜在的失效模式分析250Load-Carrying Fillet Weld:Throat versus Toe Failure承载角焊缝：焊喉与焊趾失效25

40、1Failure Mode Definitions Laser Welds失效模式定义：激光焊(a)Sheet failure mode definition for laser welded coupons激光焊板失效定义(b)Definitions of weld toe and sheet failure from weld root 焊趾的定义与源自焊根的板失效(c)Specimen showing“sheet failure”after fatigue test(L1)疲劳试验后的板失效样本252Equivalent Structural Stress Range vs N:Shee

41、t Failure vs Interfacial Failure等效结构应力范围与寿命N：板失效与界面失效SS wrt sheet intersection from weld element for interfacial failures源自焊接单元界面失效的交接板结构应力焊趾失效焊喉失效253Observations小 结n The same structural stress method can be used for weld root/throat fatigue failure 结构应力法同样可应用于焊根/焊喉疲劳失效分析 Need to know weld throat si

42、ze?是否需要焊喉尺寸？Recommended strategy:prevent weld throat failure at design stage by specifying appropriate weld size 建议在设计阶段指定合适的焊缝尺寸，以避免焊喉失效 S-N curve should be the same as that for weld toe failures S-N曲线与焊趾失效模式一样 n Other weld types(spot welds,plug welds,etc)其他焊接类型其他焊接类型(点焊、塞焊等点焊、塞焊等)SS method directl

43、y applicable 结构应力法直接适用 Recommended strategy:eliminate weld or interfacial failure by specifying a minimum weld size 建议指定一个最小的焊缝尺寸以避免焊缝或界面失效254Treatment of Multi-Axial Fatigue多轴疲劳的处理n An effective stress parameter measuring both normal and shear is needed 需要提供一个同时度量法向与剪切的应力参数n Local stress based para

44、meters,e.g.,by Sonsino and Kuepper(01)基于局部应力的参数(Sonsino and Kuepper，2001)n Global stress based stress parameters with stress intensity parameters in form of von Mises,Tresca,Principal,e.g.,by Maddox and Razmjoo(01)基于全局应力的应力参数与应力强度参数，包括Mises应力、Tresca应力、结构主应力等形式(Maddox and Razmjoo，2001)n Various theor

45、ies have been postulated based on local 基于局部假定的各种理论255Applications of the Structural Stress Method in Multi-Axial Fatigue结构应力法在多轴疲劳中应用n Observations 小结 Crack tends to propagates along weld toe into plate at least for the most part of life time 至少在大部分使用期限内，裂纹倾向沿焊趾向板内扩展 As a result,K is solely defined

46、 by normal stress(Mode I)and in-plane shear(Mode III)K由法向应力(I型断裂)或面内剪切应力(III型断裂)单独定义 Transverse shear often negligible 忽略横向剪切效应256Structural Stress Definitions for Multi-Axial Loading多轴载荷的结构应力定义Through-Thickness Normal Structural Stress厚度截面的法向结构应力Through-Thickness In-Plane Shear Structural Stress厚度截

47、面的面内剪切结构应力Transverse shear(Fz)is negligible in shell/plate structures 壳/板结构横向剪切(Fz)忽略不计257Structural Stress Calculations for A Plate to Tube Fillet(Sonsino and Kuepper,01)板管倒角的结构应力计算(Sonsino and Kuepper,2001)(b)Simplified shell element models of the tube-to-flange joint modeled with 两种不同单元尺寸的简化的管-法兰

48、接头壳元模型(c)Structural stress calculation results from this investigation 结构应力统计表258SAE“Weld Challenge”Specimen Loaded in Bending and TorsionSAE“焊接挑战”中弯曲与扭转工况259SS Based SCFs Calculated Tests by Four Sources 基于结构应力的应力集中系数(文献比较)(a)Multi-axial structural stress state 多轴结构应力状态(b)Structural stress based SC

49、Fs 基于结构应力应力集中系数260Structural Stress Based Approach基于结构应力的分析方法n Calculate structural stresses for pure bending,pure torsion,in-phase bending+torsion 计算纯弯曲、纯扭转、同步弯扭的结构应力n Compute equivalent stress parameter using structural stresses s and s 利用结构应力s 和s计算等效应力参数 von Mises Mises应力 Tresca Tresca 应力 Princip

50、le 结构主应力 n Out-of-phase:非协调 Miners rule Miner法则 Modified Goughs ellipse 修正的Gough椭圆方程261Multi-Axial S-N Data:Sonsino(01)&EPRI(02)多轴S-N数据(Sonsino,2001&EPRI,2002)von Mises form Mises形式：In-Phase Loading同步载荷262Multi-Axial S-N Data:Sonsino(01)&EPRI(02)多轴S-N数据(Sonsino,2001&EPRI,2002)In-Phase Loading同步载荷263