Bending beam Safety Factor

[MaxOtis]

Hello guys,

I am designing rollers with a uniform load on top of it and are simply supported, as follow: http://www.engineersedge.com/beam_be...m_bending1.htm

Yet all the information I found online seems to neglect the shear stress that would be maximum at each support. I understand that the shear will be neglectable on a long beam, but for the design of a small roller (200-300mm) the shear might be important.

So my question is: how would you analyse it ? Am I wrong to consider the shearing ? Should I calculate 2 safety factors (one for shear at the supports, and one for bending stress in the middle), or would the roller fail in between with a mix of shear and bending stress ?

Can you please direct me on the good way.

Hope it make since and sorry for my English as it is not my main language.

Thank you.

[jboggs]

MaxOtis,
Welcome to the forum.
Your question and the page you linked to is about beam calculations, but you also ask about rollers. I am confused. A sketch would help would help us all understand what you are trying to do.

[PinkertonD]

There are a lot of unknowns in your quest. How many or how few rollers will be supporting the full load at any one time?
You are looking at two separate entities, one, the method of supporting (mounts) the rollers to carry the load, and two, the beam supporting the array of rollers.

Within those two simple items there are a plethora of things that become involved. As JB s***est, a drawing or skecth will go a long way towards helping you get started.

[RWOLFEJR]

Hi Max,
It's good that you are giving consideration to all possible modes of failure. Yes... You need to look at both. Far as the safety factor goes... Apply your desired factor of safety to both shear and bending and whichever beam is suitable for one mode of failure and more than enough for the other is the winner.