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##### Analyzing & Optimizing Stiffened Panels / Re: Free Body Loads and Stress Calculation for Simple Panel

« Last post by**Stephen**on

*March 12, 2018, 02:11:34 PM*»

Hi jsanc,

It looks like there are two things going on here.

First, since this is effectively a rectangle with width 2" and height 1", the moment of inertia about the centroid of the cross-section is 1/12*(2in)*(1in)^3 = 1/6 in^4. If you do use the parallel axis theorem with two 0.5" plates, the offset of each, y, should be 0.25", since this is the distance from the midplane of the section to the centroid of each plate. Of course these two values should come out the same.

When we apply moments in HyperSizer, we do so using running load. That means that any moment you apply has units of "in*lb/in", not just "in*lb". In this case, Mx is defined in terms of in*lb of moment per inch of x-span. So your Mx for verifying the calculation should be (10000 in*lb/in)(2in)=20000 in*lb.

Feel free to respond if you need clarification on anything!

It looks like there are two things going on here.

**Moment of intertia calc**First, since this is effectively a rectangle with width 2" and height 1", the moment of inertia about the centroid of the cross-section is 1/12*(2in)*(1in)^3 = 1/6 in^4. If you do use the parallel axis theorem with two 0.5" plates, the offset of each, y, should be 0.25", since this is the distance from the midplane of the section to the centroid of each plate. Of course these two values should come out the same.

**Moments applied in HyperSizer**When we apply moments in HyperSizer, we do so using running load. That means that any moment you apply has units of "in*lb/in", not just "in*lb". In this case, Mx is defined in terms of in*lb of moment per inch of x-span. So your Mx for verifying the calculation should be (10000 in*lb/in)(2in)=20000 in*lb.

Feel free to respond if you need clarification on anything!