Abstract
Complex structure system fatigue life experiment is very expensive and usually we can afford only one or two such fatigue life experiments. Yet, in engineering, we need absolutely to know its safe fatigue life. We aim to provide a simple and reliable method for predicting safe fatigue life of complex structure system. Based on the enumeration of the significant fatigue failure modes of structure system and one-sided tolerance factor, an algorithm for predicting fatigue life of complex structure system is presented. By employing FEM (finite element method) and material fatigue life curve, fatigue life values of the significant fatigue failure modes of complex structure system are obtained, and these fatigue life values are taken as samples of structure system fatigue life population. Further the lower confidence limits of fatigue life are predicted by using the one-sided tolerance factor. A logarithm criterion is presented for the enumeration of the significant fatigue failure modes, which reduces the possibility of missing important fatigue failure modes. A method with high precision is programmed for computing the one-sided tolerance factors. Finally we give a numerical example. When using logarithm criterion we needed to set a value on threshold C; we used 0.8 and 0.9 as two different values of C; after careful consideration, we recommend the selection of C=0.9. For C=0.9, we obtained safe fatigue life of the complex structure system in numerical example as 7.626×105 cycles for reliability R=0.90 and confidence γ=0.90, and 7.339×105 cycles for R=0.99 and γ=0.95.
| Original language | English |
|---|---|
| Pages (from-to) | 435-439 |
| Number of pages | 5 |
| Journal | Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University |
| Volume | 23 |
| Issue number | 4 |
| State | Published - Aug 2005 |
Keywords
- Complex structure system
- Fatigue life
- One-sided tolerance factor
- Significant fatigue failure mode