Physics/Statics Experts, I need your help.

[af1 1982]

Hey guys, I'm buildinh an eletric powered vehicle right now for a school projet. The motor is fastened to a steel plate by zinc bolts. How would I go aboutfiguring out the maximum amount of shear force these bolts can handle before breaking. Thanks

 

[dunkinlo]

just make sure they're good and tight.
but I'd to 50-70 in lbs. of torque because thats what they use on all vehicle bolts

 

[af1 1982]

Okay thanks. Would you know how to calculate the shear stress mathematically because I need to show my Professor proof that these bolts will or will not hold

 

[offbad]

Originally Posted by af1 1982

Okay thanks. Would you know how to calculate the shear stress mathematically because I need to show my Professor proof that these bolts will or will not hold

don't you have a textbook for this type of thing?

 

[td the god]

Originally Posted by af1 1982

Hey guys, I'm buildinh an eletric powered vehicle right now for a school projet. The motor is fastened to a steel plate by zinc bolts. How would I go about figuring out the maximum amount of shear force these bolts can handle before breaking. Thanks

I got you....give me a second...easy calculation....be right back

 

[td the god]

to calculate the shear load of the bolt, you simply multiply the dia of the bolt by the length of engagement into the material (be it a housing or a nut). This gives you the area of the thread under load. If a bolt (or screw) is to shear, it will fail across the thread.
Just use this area in the general equation:
in your case, just assume the load is acting across the cross section of the root of the thread, and devide the load by that area.
The max shear loads can be found in the back of most bolt/screw producers catalogues.
Just got to use the Torque (max motor output) = Force x Radius(of the gear orsprocket).....to determine the Force....assume it is in the X direction, because, like said above, that would be the manor in which the bolt would fail

then just apply this equation to get your answer and compare to the max of the bolt you areusing.....

IMO tho, Zinc is not strong at all....why aren't you guys using Steel or at least Aluminum?


*edit: there is much more to solving this....however, I cant find my textbook that goes into material strength

 

[ptrakarn23]

i cant tell if thats BS or some knowledge

 

[ninjallamafromhell]

Originally Posted by TD The God

to calculate the shear load of the bolt, you simply multiply the dia of the bolt by the length of engagement into the material (be it a housing or a nut). This gives you the area of the thread under load. If a bolt (or screw) is to shear, it will fail across the thread.
Just use this area in the general equation:
in your case, just assume the load is acting across the cross section of the root of the thread, and devide the load by that area.
The max shear loads can be found in the back of most bolt/screw producers catalogues.

Just got to use the Torque (max motor output) = Force x Radius(of the gear or sprocket).....to determine the Force....assume it is in the X direction, because, like said above, that would be the manor in which the bolt would fail

then just apply this equation to get your answer and compare to the max of the bolt you are using.....

IMO tho, Zinc is not strong at all....why aren't you guys using Steel or at least Aluminum?


*edit: there is much more to solving this....however, I cant find my textbook that goes into material strength






I'll see what I can dig up right fast.

 

[al audi]

im just in here to learn something new

 

[ninjallamafromhell]

So far what I got is:
http://www.portcitygroup.com/pdf/alloys.pdf
http://en.wikipedia.org/wiki/Tensile_strength
http://www.simalex.com/material.htm

From what I can tell you just need to take a cross sectional area and use the tensile strength of whatever zinc alloy you're using. Hopefully a Mechanicalengineering can back this up or correct it. I'm just an Electrical engineer in training

 

[thewealth]

Originally Posted by ninjallamafromhell

So far what I got is:
http://www.portcitygroup.com/pdf/alloys.pdf
http://en.wikipedia.org/wiki/Tensile_strength
http://www.simalex.com/material.htm

From what I can tell you just need to take a cross sectional area and use the tensile strength of whatever zinc alloy you're using. Hopefully a Mechanical engineering can back this up or correct it. I'm just an Electrical engineer in training

Your question seems a bit vague, but this sounds about right. But I'm a EE in training too (we don't get as deep into it). Good luck.