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?