Learning Forum

[SamerAli]

In this Figure, if it is a rectangular beam (0.2 ft * 0.2 ft) and the material is Structural steel how can find a maximum force (shown in the figure ) if the safety factor is 2 ?? Please help me !

[peteroznewman]

I suggest you use simply supported beam equations to calculate the value.
Look up the equation for the maximum bending moment for this configuration.
It has a term in it for moment of inertia, I, so look up the formula for that for a square cross-section.
Look up the equation for the maximum stress given the bending moment.
Look up the strength of structural steel. You need to use the safety factor on the Ultimate or the Yield Strength.

[SamerAli]

peteroznewman
To clarify more.. I have an unknown Force, but the Safety factor is known = 2. Is there a property in the Ansys that I can find the maximum force at this safety factor?

[peteroznewman]

Yes, the problem is clearly understood. Let me clarify how to use that with the yield strength. Divide the yield strength by 2 to obtain the target value of stress.
Substitute that value of stress into the equation to calculate the bending moment.
Substitute that value into the bending moment equation that has a force input and you have your answer.
If you don't want to use a few simple equations to obtain the force, you could build a model in ANSYS.
That means draw the geometry, mesh the geometry, apply the support, apply a 100 lb load, plot the Safety Factor, then scale the load to get a Safety Factor of 2.
I could do that in 10 minutes because I am expert at using ANSYS, or I could write out the few simple equations and get an answer in 2 minutes.
If you don't know how to use ANSYS, it might take you many hours to learn how to do that, which would be a great learning experience.
Or you could spend an hour and look up the few simple equations and get an answer that way. Either way, you will learn a lot.

[SamerAli]

Thank you can you explain bt photo or not ? The other question .. Is the method of experimentation correct? The intent is to set random values for the force and look at the safety factor. When the force becomes the safety factor with results = 2, this force is considered .. Is this method correct?

[peteroznewman]

Start with the Yield Strength and the Safety Factor and work back through the equations to calculate the maximum force. There is no need to guess random values if you can do algebra on simple equations.
Have you looked up any beam bending equations?

[SamerAli]

ok .. Such as the yield strength is 150 MPa (For ex ) and FOS =2 , then the max stress 150/2 = 75 MPa , after that, I search about force (from ansys ) that give me this stress right?

[peteroznewman]

Yes, that is the maximum allowable stress in the beam.
Next you use the equation that calculates the stress for the bending moment on the beam.
For your diagram, c = 0.1 ft, but you have to use a consistent set of units. So you should use lbf and inch, so c = 1.2 inch. This means you have to convert the Yield Strength and allowable stress into psi (pounds per square inch).
The equation for M = FL/4 where L is the length of the beam in inches and F is the force in lbs. F is the value you are looking for.
The value of Ic is the area moment of inertia. See if you can find an equation for a square or rectangle.