studying-engineering: Printable Steel and Timber Design Cheat...

studying-engineering:

Printable Steel and Timber Design Cheat Sheet (long)

Just message for corrections :)

This is great, but also reminds me about how much I hate doing this…

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More Than You Ever Wanted to Know About Mechanical Engineering, Part 34: Residual Stresses

engineeringtldr:

Fatigue failure is basically tensile in nature. It occurs when parts are repeatedly stretched beyond the limits of their material. One way a designer can compensate for this is to make parts with compressive stresses built into them to counteract the tensile stress they’ll encounter during use.

It’s important to understand that pretty much any process that deforms material creates residual stresses. They’re an inavoidable result of the process of manufacture. For many parts, it’s not something that has to be taken into account, but it becomes important in some applications. (For some plastic parts, for example, it’s common to stress-relieve parts after they’re machined by annealing to reduce internal stresses created during machining that may cause premature failure.) However, in the case of a part where we know it will be subjected to tensile stress, it may be desirable to deliberately process the part to introduce a compressive residual stress.

There are a number of ways to accomplish this. It can be done by hardening, in which the part is heated and then quenched, or by mechanical compression of the part’s outer layer with a process like shot peening (where pellets of some kind are literally shot at the piece) or hammer peening (exactly what it sounds like).

When you build in compressive stresses like this, you are giving the part a greater tolerance of tensile loads, but you’re also creating a tensile stress within the part itself in a neutral state to counterbalance the compression. So in using these techniques, it’s possible to go too far and create a part that will fail early due to its own internal stresses. Used correctly, however, adding a compressive layer to a part can significantly lengthen its life.

This is cool.

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More Than You Ever Wanted to Know About Mechanical Engineering, Part 31: Goodman Diagrams

More Than You Ever Wanted to Know About Mechanical Engineering: S-N Diagrams

studying-engineering: Managed to finish this with less than 2...

studying-engineering:

Managed to finish this with less than 2 hours before submission 😓

Ugh. So glad to be done with statics.

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More Than You Ever Wanted to Know About Mechanical Engineering, Part 27: Strength Correction Factors

More Than You Ever Wanted to Know About Mechanical Engineering, Part 25: Fatigue Failure