v818multimscformat.pptVIP

E-N Theory Continued and Dealing with Multiaxiality;Sharp and Mild Notches;Refinements to the Neuber Method;Neuber Method - Formulation Used in Software;Seeger-Beste Method and Mertens-Dittman Method;e;Seeger-Beste Method;对低地周疲劳分析，Neuber方法出入较大，应使用Seeger-Beste 或 Mertens-Dittman 方法， 被称为形状系数或有限载荷比。Lp是截面进入塑性时的载荷；Ly是截面全体进入塑性的载荷； 的 值一般为1.5到3。 ;形状系数（塑性应变集中系数）Shape Factors (Plastic Strain Concentration Factors);Bar with Mild Notch in Torsion;Dealing with Multiaxiality;在产品设计开发过程中，疲劳分析日益重要Fatigue analysis is an increasingly important part of the design and development process 许多部件都处于多轴应力状态，其中一些并在临界状态情况下处于多轴应力状态Many components have multiaxial loads, and some of those have multiaxial loading in critical locations 单轴分析方法给出的结论较差，需较大的安全系数做保证Uniaxial methods may give poor answers needing bigger safety factors 疲劳分析需要由测试和有限元的计算结果相结合Fatigue tools need to work from measured and FE-derived strains;The Life Prediction Process e - N Approach;2-D Stress State;3-D Stresses;Tensor Representation of Stress State;Strain Tensor;Transformation of Co-ordinates;Stress Tensor Rotation;Principal Stresses (and strains);Mohr’s Circle for Stress (2D);Mohr’s Circles for Triaxial Stress;Generalized Hooke’s Law for 3-D;Generalized Hooke’s Law for 3-D;Free Surface Stresses;多轴评估Multiaxial Assessment;Example: Near Proportional Loading;Example: Near Proportional Loading;The left plot indicates that the ratio of the principal stresses is nearly fixed at around 0.4, especially if the smaller stresses are ignored. The right hand plot shows that the orientation of the principal stresses is more or less fixed. This is effectively a proportional loading (these calculation assume elasticity);Example: Non-Proportional Loading;Example: Non-Proportional Loading;Effect of Multiaxiality on Plasticity, Notch Modelling and Damage Modelling;Exercise Perform Quick Start Guide Chapter 11 Lesson “A Multiaxial Assessment” Sections 11.1 through 11.4 where you will assess whether or not the stress state i