8
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Why do car-seats have an expiration date?
It's a combination of 1, 3, 4, the product development cycle, and the nature of the product.
1 - Damage in materials is a cumulative process, the product of hundreds or thousands of little events (e....
- 2,145
4
votes
Accepted
Fatigue resistance at filleted corners - Design detail
I have seen 'lollipop cutters' used for this purpose, just a single pass into the side (closest to option B). The thickness of the shank means it's not a perfectly square bottomed slot, but was ...
- 7,726
3
votes
Accepted
Infinite life of a material, Fatigue Strength
Studies on fatigue life estimations was first done on steel axis in trains and continued on for other steel constructions. The majority of the fatigue publications have been based on fatigue ...
- 187
2
votes
stress wave propogation in metals
I think this is more a comment than an answer, but I have too small reputation to comment (poor me!).
Summarizing, you are asking: how dynamic loads propagate inside a structure?
I would underline ...
- 41
2
votes
How does the S-N curve (or Wöhler curve) of a material change with frequency?
If, for any reason, the fatigue process becomes time-dependent, then it also becomes frequency-dependent. Under normal conditions, fatigue failure is independent of frequency. But when corrosion or ...
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2
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Shell vs. solid elements for a fatigue analysis using FEM
It really depends a lot on your model and types of loads but here are some generalities:
Shell elements usually require a lot less computational work than solid elements. This means that you can ...
- 170
1
vote
1
vote
Accepted
Strength of bolts
Simply put this is a textbook example of what not to do.
The geometry of the connection, a solid bar to a narrow bolt invites stress concentration at the necking where the bolt enters the rod.
The ...
- 22.1k
1
vote
What does cycle mean in fatigue strength diagram?
The cycles in the diagram are cycles since the structure was manufactured. It is not reset to zero automatically! A typical shaft will reach high numbers pretty quick.
In some situations, you can ...
- 41
1
vote
What does cycle mean in fatigue strength diagram?
A cycle in terms of fatigue strength is going from no load to full load back to no load.
The frequency that the load is applied and removed is measured and there have been some well-documented ...
- 15.5k
1
vote
Find hotspots in a system
There are some image analysis algorithms used for tracking that can be used for that (e.g. Blob tracking with OpenCV):
threshold the image (it should be very straightoforward in your case). For ...
- 24.3k
1
vote
Looking for a compression spring alternative with 10x lifespan
Compressed air like an air suspension in a car or truck. 100K is not many cycles for a steel spring; springs such as engine valves run many ,many millions of cycles ,normally without failure.
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1
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Shell vs. solid elements for a fatigue analysis using FEM
Bottom Line is that either can be used successfully if properly applied.
The most appropriate has to do with:
the application and (e.g. symmetries in geometry vs. irregular shapes and loads)
what ...
- 24.3k
1
vote
mean fatigue strength
Fatigue is failure cause by cycling loads which do not exceed the yield stress of the material, typically over tens of thousands of cycles. Not to be confused with work hardening which occurs over ...
- 15.2k
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