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8 votes

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....
DLS3141's user avatar
  • 2,145
4 votes

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 ...
Jonathan R Swift's user avatar
3 votes

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 ...
loStraniero's user avatar
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 ...
Fabio M's user avatar
  • 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 ...
Mark's user avatar
  • 5,333
2 votes

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 ...
JC ME's user avatar
  • 170
1 vote

Difference between failures

Nope. it is called erosion in the materials science field.
niels nielsen's user avatar
1 vote

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 ...
kamran's user avatar
  • 22.4k
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 ...
marius's user avatar
  • 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 ...
Solar Mike's user avatar
  • 15.8k
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.
blacksmith37's user avatar
  • 6,144
1 vote

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 ...
NMech's user avatar
  • 24.4k
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 ...
Chris Johns's user avatar
  • 15.2k

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