PDF《Combining KISSsoft&KISSsys with》

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8 The basic prinicple is to estimate the lifetime based on the elastic-plastic, local stress in the critical section compared to the S-N curve derived from the un-notched probe under uniaxial load. In the course of the FKM-guideline, the local stress concept is modified to a purely elastic load situation. Precondition for the use is hence an elastic material state. In this context, the concept used is not really a local concept as the elastic-plastic notch root strain concept but a concept close to the nominal stress concept except that the notch coefficient is "on the other side ofthe equation". It is a useful tool for the static and high cycle fatigue proof. Input: Stress amplitudes and stress ratio at the proof point and at a support point. Or the stress amplitudes / stress ratio at the proof point and an estimate for the support coefficient. Furthermore, for the calculation of the design factors, parameters like surface roughness, heat treatment and so on are required. Then, load data like number of cycles, temperature, collective are also required. Output: A static and fatigue utilisation (inverse of a safety number) is calculated. The proof is documented in detail. Figure 6-4 Documented proof of integrity of the housing for a given feature and its stress state