Shear strength to Spring force calc

[spider80]

Hello,
I am trying to find a way of calculating the shear strength caused by a spring force acting perpendicular to the direction of shear. I am a little out of touch with my basics and just remember that there is a relation ship.
Could anybody out there throw me a pointer or two?
Thanks

 

[Philrock]

Need a better explanation of your problem/question.

 

[spider80]

Ok. I have a quick release pin (the kind that we see in gym's to lock the bench in a position) the ball is pushed up with a spring from inside the pin. When you slide this pin into an approp id, the balls move down due to spring compression and allow you to slide the pin inside. Once out of the hole the spring pushes the ball out again and the pin is locked.
To get it out you just have to app a force perpendicular to the spring force enough to overcome the spring force and friction. The spec I get though (from the comp) is only shear strength in lbs, while am looking for a way to calc the spring force lbs/in.
Hope that is a better explanation...
Thanks

 

[ivymike]

I'm sure the shear strength is for the pin itself (against breaking), not for the locking mechanism.

To calculate the horizontal force required to compress the ball&spring, you should start with a diagram of the system, showing the ball on spring in a guide, with some assumption about where contact between the ball and the mating structure will occur. Assume the force between the mating structure is close to perpendicular to the ball surface at the interface, and resolve the force into lateral and axial components. You could assume some coefficient of friction between the ball and its guide, and use the lateral component of the ball-structure force in that calculation.

Haven't given it much thought... that's just what I came up with while typing. Draw the picture and add to the above.

 

[rb1957]

i don't think there is a relationship between shear strength and spring stiffness ... spring's are not usually used in shear, i tend to agree with ivymike (the shear strength you have is for the pin, and unrelated to the spring)

i you want an exact number (and if you have a spring) whay not test it and calc ... k = X lbs/Y"(compression).

if you want an approximate number, i guess you're applying about 10 lbs force to compress the spring the radius of the ball (say 0.1") ... so spring stiffness would be about 100.

good luck

 

[israelkk]

Can you give the pin/spring/ball catalog number and manufacturer web page?