A　micromechanics　model　and　a　computational　homogenization　method　were　developed　to　examine　the　macroscopic　elastoplasticity　and　yield　behavior　of　closed-cell　porous　materials　with　varied　inner　gas　pressures.　For　the　uniaxial　stress-strain　relation　of　the　porous　material,　the　micromechanics　model　coincides　well　with　the　numerical　homogenization,　especially　for　the　case　of　relatively　low　porosity　and　gas　pressures.　The　effects　of　the　combination　of　the　different　gas　pressures　on　the　uniaxial　stress-strain　curve,　the　nominal　Poisson＇s　ratio,　yield　surface　and　initial　yield　strength　of　the　material　are　systematically　investigated.　The　multiple　gas　pressures　can　induce　the　tension-compression　asymmetry　of　the　uniaxial　stress-strain　curves　and　the　nominal　Poisson＇s　ratio　of　nonlinear　deformation.　In　particular　it　is　shown　that　when　the　multiple　gas　pressures　coincide,　the　yield　surface　of　the　porous　material　with　inner　gas　pressures　can　be　simply　obtained　from　that　of　the　porous　material　without　inner　pressures　by　a　shift　along　the　negative　direction　of　the　hydrostatic　stress　axis.　However,　when　the　multiple　pressures　are　different,　in　addition　to　a　translation　along　the　hydrostatic　axis,　the　yield　surface　undergoes　a　change　in　shape　and　size,　and　the　maximal　equivalent　stress　is　lowered　by　a　difference　in　gas　pressures.　Furthermore,　the　multiple　gas　pressures　have　a　significant　effect　to　reduce　the　yield　strength　of　the　closed　cell　porous　materials.　(C)　2014　Elsevier　Ltd.　All　rights　reserved.