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Questions tagged [fatigue]

24 questions
11
votes
3 answers

Why do beverage can tabs break when bent?

Most people have had the experience of moving the tab of an aluminum can back and forth until it breaks off. It usually only takes a few complete back and forth motions before the tab breaks off. What is the root cause of the tab breaking off? The…
hazzey
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Why do car-seats have an expiration date?

My wife and I are expecting our first child, and therefore are expecting to purchase a car seats. My wife and I have discovered that car seats have "expiration dates": a car seat, no matter how lightly used, is deemed unsuitable for use after a…
PipperChip
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5
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2 answers

How does the S-N curve (or Wöhler curve) of a material change with frequency?

How a Material fatigues can be characterized by a Wöhler curve where each datapoint corresponds to a failure with the stress on the y-Axis and the number of cycles on the x-axis. An example is the following Wöhler curve: How does this curve change…
JHK
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4
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1 answer

Fatigue resistance at filleted corners - Design detail

So, I have a situation where we are putting load on a plate from above, and the plate has a step in it, which was made by milling a bigger block of steel (i.e. there are no layers and everything is homogeneous). Conventional engineering knowledge…
Isa
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3
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3 answers

Do I use alternating, mean or max/min stresses for Miner's rule?

I am trying to work out fatigue life of a part using Miner's rule, however I am having some trouble working out which stress values to use. I have seen some examples but there seems no rhyme or reason to the values they have used in the accumulative…
david_10001
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1 answer

Strength of bolts

I was wondering if it'd be a good idea to attach a 10kg load to the end of a movable steel rod by fastening it with just one M5 bolt. Looking at Misumi's datasheet, M5 (Class 10.9) has an allowable load of 111kgf. 111kgf is 10x more than my…
Kar
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How do I implement scientific experiment to derive a equation called Gerber Line?

How do I implement scientific experiment to derive a equation relevant to subject of stress and fatigue called Gerber Line equation? May you also provide some historical context to that?
Victor
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1
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2 answers

Infinite life of a material, Fatigue Strength

After 10^6 cycles a component is considered to have infinite life. What makes 10^6 cycles a deciding factor for infinite life? Why not 10^8?
Reo Ashwin
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1
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2 answers

Shell vs. solid elements for a fatigue analysis using FEM

What are the advantages and disadvantages of using quads (shells) vs using hexas (solid) in my mesh for a fatigue analysis using a finite element software. Thanks.
user3408085
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Abaqus vcct fatigue consistently underpredicts disbond growth rate

I'm modelling a fatigue disbond using abaqus. I've understood the disbond growth rate is equal to: $$\dfrac{\partial a}{\partial N} = c_3 \Delta G^{c_4}$$ I've set up an analysis with MMB specimen. I've set $c_3 = 5.59\times 10^{-20}$ and $c_4 =…
Nathan
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Would Amorphous Diamond-like Carbon coatings have a fatigue cycle limit?

I'm aware that polymers like most plastics can go through stress cycles indefinitely as long as the covalent bonds are not ruptured. On the other hand, I hear that even metals like steel and titanium do have limited life-spans no matter how small…
Anthropologist
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Is there any link between tensile strength and endurance limit for steel ?

I'm designing a shaft, and i have to choose a material. I deal with cyclic stress in my machine, so i set up an expression for all the possible stresses and combined it with von Mises criteria for plastic deformation, it gives me the so called…
user14407
1
vote
1 answer

stress wave propogation in metals

Over years of flying small airplanes I have seen fatigue cracks and frayed brackets and connections. I wonder if there is an easy way to search the propagation of stress wave in machinery and connection brackets and parts. I am not concerned here…
kamran
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Addressing Variations in Stress Levels for Accurate Fatigue Analysis of Crankshafts

In analyzing the fatigue resistance of a crankshaft, how should we account for the variation in stress levels throughout its 360-degree revolution? Given that the crankshaft is subjected to different forces and stress levels at different positions,…
amirhosein majidi
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Identifying Marin Factors In Ansys For Fatigue Analysis

I am conducting a fatigue analysis for a mechanical shaft on ANSYS. Everything is fine except for defining marin factors. I am eager to specify some crucial marin factors, such as the temperature factor, which, in my case, will significantly reduce…
Jesse Flynn
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