## elica85 3 years ago can anyone help with mechanics of materials?

1. elica85

2. abstracted

I can't tell what the 4 shaded shear planes are. Can you try taking a clearer picture of the two pictorials?

3. elica85

the planes are parallel to the front plane

4. elica85

5. abstracted

I think I know the orientation it's supposed to be, but the bottom picture is difficult to decipher

6. elica85

|dw:1340762720808:dw|

7. windsylph

you can also try the engineering study group

8. elica85

thx i have, no one's ever there. my ? was posted there first

9. windsylph

haha i see.. with the level of the course you're taking, you're bound to get a lot less help here in openstudy..

10. abstracted

I took this course a couple semesters ago, I just have to go through my old book to refresh my memory >.<

11. windsylph

oh okay haha. my sister's about to take it next semester or so. she's taking statics and particle dynamics right now.. how's mechanics of materials compared to that so far?

12. abstracted

Mechanics of materials does build off the very basics of statics, not so much dynamics. I personally liked MME far more than statics. Except I had to take statics and dynamics crammed in the SAME course...

13. windsylph

haha same with my sister. i guess it's the standard course material across universities..

14. elica85

nonsense, plenty of smart people here :) @abstracted if you figure it out, pls feel free to help. i have to sleep. what i did was avg shear stress=shear force/area. i used 500kPa to set as avg shear stress and for shear force i set V=P/2 since i used just one side of connection and divide by 2 since everything else is assumed to be equal so load is half if only one bolt is considered. used the plane for area which is 0.1m*0.1m. my answer for P is 10kN but book says 9.05

15. elica85

i prefer statics much more but this is summer course so materials are very condensed.

16. windsylph

haha yep. my sister's taking summer school too, but with statics and particle dynamics lol. by the way I can't help on this one, I'm a computer engineer lol

17. elica85

it's ok, thx for looking. particle dynamics sounds nasty 0_o

18. abstracted

mme gets better, the first 6 or so chapters were very boring to me. It gets interesting when you get to bending moments/beam deflections

19. elica85

bending moments were covered in the first chapter

20. abstracted

typo, bending/flexural stresses*

21. elica85

o yea, haven't heard of it yet. anyway thx. gonna try again tomorrow.

22. abstracted

I got 9.05 kn, see below: $\tau = \frac{V}{A}\rightarrow V=\tau A$ In the case for the bolts:$V=\frac{P}{4}$$A= \pi(0.003m)^2=2.8274(10^{-5})m^2$$\tau = 80MPa=80(10^6)Pa$ The shear force is 1/4 of the load because you must take into consideration both ends of both bolts; just like they take into consideration both sides of both bolts (the four shaded planes). See the attached image, all four shaded areas represent an individual shear. Plugging everything in and solving for P; $P_{bolts}=4(80MPa)(2.8274(10^{-5})m^2)=9.048kN$ And I got $P_{planes}=20kN$ So the answer is the smaller one: 9.048kN

23. abstracted

There are some tools that may prove helpful for your class (they did for me). The authors of my text book created a website full of animated examples for every chapter (does not require log in) http://web.mst.edu/~mecmovie/ The authors of a different mme book created a very simple software that you can use to calculate nearly everything you come across in this class. http://www.mdsolids.com/

24. elica85

thx so much and thx for the references!

25. abstracted

No problem, feel free to ask me any mme questions in the future, I loved this class!