Palavra-chave: LIMIT CYCLE

CENTER INVARIANT TORUS ESTABILIDADE ESTRUTURAL INTEGRABLE SYSTEMS BIFURCATIONS ATTRACTOR AVERAGING PERIODIC ORBIT ISOCHRONOUS CENTER SISTEMAS DINÂMICOS SINGULARIDADE BROWER THEORY LINEAR VECTOR FIELD SINGULARITY LIENARD EQUATION EQUILIBRIUM PIECEWISE SMOOTH SYSTEMS BIFURCATION NONSMOOTH DYNAMICAL SYSTEMS REGULARIZATION INVARIANT VARIETY SYNCHRONIZATION POLICYCLE MINIMAL SET ASYMPTOTIC STABILITY NON-SMOOTH VECTOR FIELDS AVERAGING METHOD LIAPOUNOV-SCHIMIDT REDUCTION AVERAGE DULAC PROBLEM HAMILTONIAN PENDULUM