In　this　work,　the　dynamics　of　a　truss　core　sandwich　beam　with　NES　(nonlinear　energy　sink)　device　are　investigated.　Based　on　the　principle　of　nonlinear　TET　(targeted　energy　transfer),　an　NES　device　is　placed　in　the　interior　of　a　sandwich　beam　to　suppress　vibration　of　the　beam.　The　governing　equation　of　motion　for　the　sandwich　beam　with　NES　device　attached　is　derived.　The　vibration　responses　of　the　system　are　analyzed　under　impulse　and　harmonic　loads.　Feasibility　of　the　vibration　suppression　scheme　is　demonstrated　by　investigating　the　relation　between　the　mass　of　the　NES　device　and　suppressing　effect　as　well　as　the　relative　motion　between　the　sandwich　beam　and　the　NES　device.　In　addition,　the　influences　of　the　NES　parameters　on　the　suppressing　effect　are　studied.　It　is　worth　noting　that　the　vibration　suppression　is　enhanced　with　increasing　the　damping　of　NES　when　the　system　is　excited　by　harmonic　loads　and　with　decreasing　the　damping　when　the　system　is　excited　by　impulse　loads.　The　influence　of　the　nonlinear　characteristic　of　spring　on　the　vibration　suppression　depends　on　the　selection　of　the　other　parameters　of　the　NES.　(C)　2017　Elsevier　Ltd.　All　rights　reserved.