We show that the minimization of total potential energy is the general principle
behind the well-known rule of maximizing some lengths of a truss mechanism to
define a tensegrity. Moreover, the latter rule is a special case, due to the
usual high values of the modulus of elasticity. An innovative mathematical
model is presented for finding the form of tensegrity structures, based on the
finite element method and on mathematical programming. A special line
element that shows constant stress for any displacement of its nodes is used to
define a prestressed equilibrium configuration. Form finding is formulated
as an unconstrained nonlinear programming problem, where the objective
function is the total potential energy and the displacements of the nodal
points are the unknowns. A connection is made with the geometric shape
minimization problem, defined by a constrained nonlinear programming problem. A
quasi-Newton method is used, which avoids the evaluation of the tangent stiffness
matrix.