Mechanics help

Can anyone help me with this engineering problem

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Do you know how to calculate the second moment of area?

Maximum deflection will be at the end, and I'm assuming that there is no external loading and that it's simply bending due to self weight?

Reply 2

thefish_uk

Original post by Smack

Do you know how to calculate the second moment of area?

Maximum deflection will be at the end, and I'm assuming that there is no external loading and that it's simply bending due to self weight?

What Smack said.

Also, depending on whether you've looked at this in your course yet you are you might need to take into account the fact that section (c) (the angle) will also deflect sideways due to it being asymmetric about the axis the force is applied along.

Reply 3

kopkitty

Original post by Smack

Do you know how to calculate the second moment of area?

Maximum deflection will be at the end, and I'm assuming that there is no external loading and that it's simply bending due to self weight?

I've worked out the second moment of area for a) but I do not know what to do next, I think it's related to the EI dv^2/dx^2 = -M equation but i'm not sure? And if it is how do i work out dv^2/ dx^2 and and E ?

Reply 4

Smack

Volunteer Team

Original post by kopkitty

You could derive it from first principles or you could just plug the numbers into a formula. As a note, are you given the Young's Modulus, or is it okay to assume that since it's steel it's about 210GPa?

Reply 5

kopkitty

Original post by Smack

All i am given is density, not sure how I can work out E from that? Maybe I just use 210 GPa, however I do not understand the d^2v/dx^2 bit how do I work that out and how do i get the -M for this shape?
Thanks

Reply 6

Smack

Volunteer Team

Original post by kopkitty

Draw a bending moment diagram, then work out the bending equation, and using Macaulay's convention differentiate it twice.

Reply 7

kopkitty

Original post by Smack

Draw a bending moment diagram, then work out the bending equation, and using Macaulay's convention differentiate it twice.

I'm not sure how to do a bending moment diagram? Any tips or videos that will help?

Reply 8

Smack

Volunteer Team

Original post by kopkitty

I'm not sure how to do a bending moment diagram? Any tips or videos that will help?

Have you not covered this in your lectures so far? You must have if you're being asked to calculate deflections.

Reply 9

0le

http://www.youtube.com/watch?v=1qTOUEdne7o

and watch all parts.

Then maybe this:
http://www.youtube.com/watch?v=zfSwf7_knN

Whenever you need help, seriously, just google it. Literally type into google "bending moment videos". Spend a good 10 mins, playing around with the terms and eventually you'll find what you need.

I wouldn't be surprised if MIT had a few lecture notes on it as well.

This is relatively basic stuff and I still don't know how to do what you are doing either, so yeah, don't feel bad, lots of people find it difficult.