Testing Tensile Strength of Beams

[brezinkl]

I am testing the tensile strength of different types of beams. However, I am having trouble with my I-beams. They are very thin and tip over when I add weight to them. My question is should I support the I-beams so they don't tip over and record when they break that way, or should I leave them as they are and record when they tip over?

[Craig_Bridge]

I am testing the tensile strength of different types of beams. However, I am having trouble with my I-beams. They are very thin and tip over when I add weight to them.

It doesn't sound like you are testing the tensile strength. Tensile strength is an inherit material property that is dependent on the material and how it is processed and reflects how much force it takes to pull apart the material bonds to permanently deform or tear apart the material.

There are other "strength" properties that involve a specific configuration of the material. I suspect you are trying to measure one of these. In the case of horizontal beams, there are multiple test configurations. If both ends of a uniform beam are installed in a "pocket" or clamped configuration such that the beam can't move with a torque type force applied to a free end, then the failure mode will require two "plastic" events in order to deflect or break. If both ends are only supported below and little to no clamping force exists, then torsion and other deformations can occur. In this case, the amount of weight the beam will support before deflecting of breaking is significantly less. There is also the case where one end is clamped and the other end is free and this usually will result in a failures somewhere in between the double end clamp and the both end free case; however, it can be very close to the both end free case.

Engineers use data and formulas for both the double end clamped case and the both end free cases when designing a structure based on how the beams will be used in their design. This means we can't advise you as to which method to use as it depends on precisely what and why you are testing.

[brezinkl]

It sounds like what I am testing is the second one you described.