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Questions tagged [fatigue]

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3 votes
3 answers
463 views

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 ...
0 votes
0 answers
13 views

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 ...
0 votes
2 answers
66 views

Find hotspots in a system

In the image, I have a depicted a system which is undergoing fatigue. Using appropriate solver I have determined the life of each nodes and it is stored in a .csv file. Also I have the connectivity of ...
0 votes
0 answers
26 views

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 ...
0 votes
1 answer
31 views

Difference between failures

I'm studying about the phenomena that enlargement of the pipe entrance due to particle impingements. Our group calls this phenomena as erosion. But it seems to be fatigue failure in mechanical ...
0 votes
0 answers
13 views

Stress Amplitude Calculation in Haigh Diagram beside Limit Line

I want to use the Haigh diagram for mean stress and stress amplitude correction using SODERBERG limit line. All I can find is the relation between stress amplitude and mean stress described at the ...
-1 votes
2 answers
60 views

What does cycle mean in fatigue strength diagram?

A shaft at an usual factory might rotate 2000-3000 (10^3-10^4) per day. So, its rotation cycle easily reaches numbers indicated on X axis below. What does number of cycles in the diagram below exactly ...
1 vote
2 answers
366 views

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?
0 votes
0 answers
26 views

Costs of fatigue damage - need some statistical data / USA, Europe, Asia

I am looking for (pretty current/actual) statistical data related with Fatigue damage in machines, Annual fatigue costs in industry (for example with refference to Gross Domestic Product), time ...
0 votes
0 answers
61 views

Grain size and fatigue performance correlation for AMS 5662 Inconel 718

I am trying to do a literature review on the correlation between average grain size and fatigue performance of AMS 5662 (solution annealed condition) Inconel 718. The Special Materials Corporation ...
0 votes
1 answer
628 views

Looking for a compression spring alternative with 10x lifespan

I'm working on a project where 100k spring cycles is gonna last a few months Any recommendations on an alternative? I considered magnets but their sprigabilty isn't great (also, will they get ...
1 vote
2 answers
1k views

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.
1 vote
0 answers
50 views

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'...
2 votes
1 answer
125 views

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 ...
0 votes
0 answers
142 views

Fatigue modelling in Abaqus

My problem: I'm trying to model fatigue disbond growth in Abaqus. So far I've tried this using multiple approaches with mixed results. What I've tried: I first started with modelling a static general ...
1 vote
0 answers
25 views

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 ...
4 votes
1 answer
369 views

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 ...
1 vote
4 answers
5k views

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 ...
0 votes
0 answers
109 views

Long term deflection

I've been working with a team of 'designers' that are highly concerned over a potential failure mode of ABS plastic. Their theory is that under a static load well under the yield point of the material ...
0 votes
2 answers
213 views

mean fatigue strength

In context of machine design, what is mean fatigue strength? (as I am thinking I am mixing it up with midrange strength) In my class we deal a lot with steels and this is a low strength steel, but I ...
8 votes
2 answers
774 views

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 ...
2 votes
0 answers
48 views

How do I implement scientific experiment to derive a equation called Gerber Line? [closed]

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?
5 votes
2 answers
3k views

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 ...
1 vote
1 answer
69 views

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 ...
11 votes
3 answers
2k views

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. ...