The　global　bifurcation　and　multipulse　type　chaotic　dynamics　for　the　nonlinear　nonplanar　oscillations　of　a　cantilever　beam　are　studied　using　the　extended　Melnikov　method.　The　cantilever　beam　studied　is　subjected　to　a　harmonic　axial　excitation　and　transverse　excitations　at　the　free　end.　After　the　governing　nonlinear　equations　of　nonplanar　motion　with　parametric　and　external　excitations　are　given,　the　Galerkin　procedure　is　applied　to　the　partial　differential　governing　equation　to　obtain　a　two-degree-of-freedom　nonlinear　system　with　parametric　and　forcing　excitations.　The　resonant　case　considered　here　is　1:1　internal　resonance,　principal　parametric　resonance-1/2　subharmonic　resonance.　By　using　the　method　of　multiple　scales　the　averaged　equations　are　obtained.　After　transforming　the　averaged　equation　in　a　suitable　form,　the　extended　Melnikov　method　is　employed　to　show　the　existence　of　chaotic　dynamics　by　identifying　Shilnikov-type　multipulse　orbits　in　the　perturbed　phase　space.　We　are　able　to　obtain　the　explicit　restriction　conditions　on　the　damping,　forcing,　and　the　detuning　parameters,　under　which　multipulse-type　chaotic　dynamics　is　to　be　expected.　Numerical　simulations　indicate　that　there　exist　different　forms　of　the　chaotic　responses　and　jumping　phenomena　in　the　nonlinear　nonplanar　oscillations　of　the　cantilever　beam.　Copyright　©　2009　by　ASME.