| Life |
Available only when the fatigue study is defined with one event.
Shows the number of cycles (for constant amplitude event studies) or the number of blocks (for variable amplitude studies) that cause fatigue failure at each location. The plot is based on SN curves and the alternating stress at each location. A block is the full load history of a variable amplitude event (including the number of repeats).
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| Life (Time to failure) |
Available for fatigue studies based on linear dynamic - random vibration results. Shows the expected fatigue life for each location of the part (in the selected units of time  ). The Time to failure is calculated by:
Life (Time to failure) = Duration of random loading input /
cumulative damage ratio
For example, if a part is subjected to a random vibration loading for a duration of 4 hours, and a time to failure estimate is 2 hours at a certain location, the part is safe from fatigue failure for the first two hours of exposure to the loading. The cumulative damage ratio at the region of interest is 0.5 in this case. Failure can be expected in the part after the first 2 hours of exposure to the particular random vibration environment.
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| Units of time |
Available for fatigue studies based on linear dynamic - random vibration results. Sets the units of time in: seconds, minutes, hours, or days for the Life (Time to failure plot). |
| Damage |
This plot shows the percentage of the life of the structure consumed by the defined fatigue events. |
| Damage (over event duration)
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For fatigue events based on linear dynamic - random vibration results, the damage ratio is calculated over the time duration of the given random loading event. Different values for the duration of the random loading result in different estimates for the part's damage factor.
You can plot the expected damage ratio due to fatigue as a percentage or factor. A damage factor of 1.0 (100%) and above indicates that failure can be expected in the part for the given time duration of the random loading.
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| Load Factor |
Available only when the fatigue study is defined with one event.
Shows the load factor of safety for fatigue failure at each location. A load factor of safety of 3.5 at a location indicates that the defined fatigue event will cause fatigue failure at this location if you multiply all loads defined for the static study by 3.5.
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| Biaxiality Indicator |
Plots the ratio of the smaller alternating principal stress (ignoring the alternating principal stress nearest to zero) divided by the larger alternating principal stress. A value of –1.0 indicates pure shear, and a value of 1.0 indicates pure biaxial state. This plot can help you determine a fatigue strength reduction factor for the study.
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