Periodic impact behavior of a class of Hamiltonian oscillators with obstacles
The paper proves the existence of infinitely many periodic and subharmonic solutions of the equation \[ -x''=q(x)|x'|^2+g(t)x'+f(t) \] with an elastic impact condition in \(0\). The proof uses a change of variables which transform the equation into a new one with a superlinear nonlinearity, then the Poincaré-Birkhoff twist theorem in the version of Ding can be applied. Previous results by X. Wu are improved.
scientific article; zbMATH DE number 5673255