《ansys疲劳分析的例子》.pdf

FE-Fatigue Worked Examples Rel. 5 Page 162 2.13 Simple S-N Example – Bracket analysis using ANSYS In this example, you will use the Stress-Life (S-N) approach to calculate the fatigue life for the constant amplitude loading of a bracket. The S-N approach typically relates nominal stresses to total failure and is suited primarily to ‘long-life’ problems where there are a large number of cycles to failure ( 103 or 104 cycles). In these examples we will be using ANSYS as the solver and prepost processor. 2.13.1 Introduction This example has a bracket bolted to a box section. A vertical load is applied to the end of the bracket. This example will calculate how many times this load can be cycled (+/-) before failure will occur. Exact fatigue material properties of the steel are unknown and will be estimated from known data such as UTS (ultimate tensile strength). The following files are required for this example: bracket.db bracket.rst bracket.dac These files can be copied to your working directory using the Macros menu in the main nSoft program. Figure 184 The interface ANSYS macro is required be installed. On starting ANSYS, this menu should appear when invoking the menu path: • Main Menu General Postproc Fatigue nCode Fatigue This is trial version FE-Fatigue Worked Examples Rel. 5 Page 163 Further information on the macro functions is available in the ANSYS on-line help. 2.13.2 Reviewing Model and Stresses in ANSYS Start ANSYS Interactive. On the start up form, enter the working directory where the demo files are located. Enter the following: • Initial jobname = bracket Accept all the defaults and select Run to start ANSYS. The main interface should start. From the top