my handbook of formulas has a myriad of entries for the moment of inertia of cross sections of various shapes. but there's nada for trusses. i've got a canti-levered beam which is too heavy for the motor i'm using to rotate it. i'm trying to avoid buying a new motor by replacing the hollow cylindrical beam with a triangular warren truss. but i need equations to tell me how to dimension it to retain the same stiffness (young's modulus of elasticity). everything i've found on the net about trusses is all about how to analyse a custom truss for compression, tension, and displacement, but there are no tables which parameterize the standard truss designs and give you the formulas for things like moment of inertia. anyone know where such things can be found?

- posted
17 years ago