Fatigue Damage Spectrum

[@aditis-q6u]

How does adding enhancement and cancellation waves (based on geometry of structure) how does it affect rhe life of rhe platform joints ?

[@manjhiman8351]

28:34 where have you guys defined the other natural frequencies and whole curve for other systems so, how does this spectrum come without specifying these parameters

[@SimcenterTesting]

28:37 - it is actually a single slope linear approximation of the Whoeler curve (Basquin law N σ^b=A^b). The natural frequencies are defined by the “frequency axis parameters”. For this analysis and for SRS calculations, there is a subtle but important difference between the two, as pointed out in the articles community.sw.siemens.com/s/article/Fatigue-Damage-Spectrum and community.sw.siemens.com/s/article/shock-response-spectrum-srs

[@manjhiman8351]

How did you define the no. Of systems and their natural frequencies for an example if DUT is a bicycle then : 1. Is all the bicycle component will be counted as different system where SDOF model will be applied to each and every system (bicycle components) and similarly the natural frequency of all those components as well as there SN curve will be u still see to find the FDS curve Are my above assumptions correct or please suggest the correct assumption

[@SimcenterTesting]

Do not confuse the SDOF systems with the natural frequencies of the test object. Mission Synthesis goal is to derive the input to a test article whose resonant frequencies are unknown. FDS uses for this scope a generalized resonance model under the assumption that (unknown) resonances ultimately lead to fatigue failure. Frequency spacing limits are often suggested by standards (e.g min xx points per octave), but I find a good practice for defining the frequency spacing to quickly analyze the frequency content of the input events upfront to make sure I am not cutting out input energy. For example, if the input signals show a clear sharp peak at around 4 Hz, a 2 Hz resolution starting at 1 Hz will lead to [1,3,5, …] Hz frequency axis which will result in an interpolated value at the critical 4 Hz frequency. It would be better to start at 1 Hz and define a 1 Hz resolution (or at 2 Hz with a 2 Hz resolution, for the sake of this example).