Mechanical engineer please help

>>8423493
Also what if the center section was hypothetically stronger, then where?

>>8423493
OP you need to look up "Heat Affected Zones" (HAZ) during welding and the associated microstructural changes that occur within them

Your question is right to point out the edge regions which border the central weld as these areas are tempered by the heat (HAZ) but don't actually melt, whereas the middle section is completely molten and then recrystallised during cooling.

The answer depends on how fast the weld pool was cooled after melting as this affects grain growth and strength, but also whether any defects were introduced during welding.

>tl;dr
not enough information given

>>8423498
actually same place I guess, because there is a shear stress where the weak and strong metal meets, yes? is that the right term?

will things of different strengths always bend where they meet due to shear stress?

white ppl pls help

>>8423493
Assuming you are bending it equally from both sides, the amount of bending stress will vary linearly from the centre. The amount of deformation in the bar will depend on its material properties. The annealed part should have a high yield stress, so, so it will likely bend with the two sections meet, where the stress is highest in the weaker section. However it depends on the difference in the yield stress of the two sections and the length of the annealed section. If the difference is small and the middle section longer, it'll break in the centre.

You should be able to work it out in excel by using common bending equations and looking up the material properties

>>8423520
So, the center section of the weld is harder, only the HAZ becomes annealed? Doesn't the molten pool also fully anneal?
And how is that possible in work hardened or tempered aluminum? Surely the molten section is also weaker? Maybe just not as weak as the HAZ?

>>8423527
So I should watch another video on bending stress? Because apparently I missed something on how stress varies at different points in the beam. I just assumed stress would be highest in the center of a uniform material beam since that's the point of the moment..

>>8423543
The stress is highest at the centre. However, the amount of stress required to deform the beam depends on the material properties.The the section with the higher yield stress can take more stress before it breaks.

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>>8423493
OP your question is poorly posed:

You specify the length of the aluminium section but not the thickness of the bar or the load applied to it?

You talk about work hardened aluminium and annealed during welding but the temperature of annealing isn't specified?

Was the whole bar work hardened? Was the central section welded or just heated?

Nothing in your question is properly defined.

>>8423584
it doesn't matter since the question isn't how much it bends only where it bends. which is irrelevant to the cross section or the amount of annealing.

you are to assume that it will bend. that you are reaching and passing the yield strength of each the annealed and hardened sections.

the question is why will it square off, bending at points A instead of having a single radius bend at point B

>>8423616
Nice selective reading comprehension

You missed the part of my post where I talk about "annealing" being meaningless unless you specify the temperature.

If the WHOLE bar was "work hardened" then it will have no influence on where the bending occurs

>>8423650
It was work hardened before welding.
Aluminum comes in various tempers and work hardened strengths.
Then it gets welded and is annealed near the weld. Temperature is impossible to know, but about a 50% reduction in yield strength is assumed for most aluminums.

If it's been ANNEALED it will be softer in the middle and bend more easily. Also max bending moment will occur there.

You're seriously a ME student?

>>8423493
That's easy. You will need to add a point of fulcrum or two with a force in the opposite direction because those two forces with no other forces acting on it result in downward acceleration. Then just measure the distance between the point of fulcrum(s) to the weakest point after you bend it and there's your answer.

>>8423493
>Mechanical engineer
>Let's say I have a 1 foot
>foot
stopped reading
kys

fuck. i'm studying EE and i hope i never have to learn this crap.

>>8424764
It's your decision if you want to be narrow minded, hopefully you aren't like that regarding EE concepts, math and physics.

However, most likely you don't need to.
The only places where some ME stuff comes in for EEs are mainly electrical machines (motors, generators) and some precision mechanics in relays for example.

>>8424363
anneal


/əˈniːl/

verb

gerund or present participle: annealing

1.
heat (metal or glass) and allow it to cool slowly, in order to remove internal stresses and toughen it.

File: fucking free body diagram christ.jpg (39KB, 1181x486px) Image search: [Google]

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>>8423493
>Let's say I have a 1 foot long piece of work hardened aluminum.A 2 inch section at center of the piece has been annealed from welding.If I apply a force to each end of that piece with me hands - will it bend where the weaker annealed section meets the stronger section or will it bend in the middle of the annealed section (center of the piece)?And what is this called so I can look it up? I watched a video on bending moment but it was not helpful.pic: Does it bend at point A or point B?

>>8425314
Jesus fucking Christ OP we've given you the best answer we can with the information you've provided.

>>8425321
>Jesus fucking Christ OP
Im not OP. I Fixed OPs shit free body diagram cause it hurt my eyes. If OP is not retarded he should be able to figure out this sophomore level EZ mode problem from there.

>>8425111
>heat (metal or glass) and allow it to cool slowly, in order to remove internal stresses and toughen it.

That def is weak sauce. Go read a text on material science.

When that happens, UTS goes up, but Young's modulus goes down, because the dislocations present can migrate and annihilate one another. Annealing relieves the internal stresses present due to strain hardening. Gets easier to bend.