We consider the problem of minimizing integral functionals of the form I(u) = ?O F(x, ?[k]u(x)) dx, where O ?Rp, u:? ?R and ?[k]u denotes the set of all partial derivatives of u with orders =k. The method is based on a characterization of null Lagrangians L(?ku) depending only on derivatives of order k. Applications to elasticity and other theories of mechanics are given. © 1981.
|Number of pages||40|
|Journal||Journal of Functional Analysis|
|Publication status||Published - Apr 1981|