The Nonlinear Mechanical Hehavior Of Gradient Porous Material Structure

This paper presents the nonlinear mechanical behavior of graded porous material structures(beam and circular plate)for porosity symmetric along thickness or non-symmetric along thickness.It was assumed that the properties of the material vary continuously through the thickness of the structures.A further study is carried out to investigate the effects of pores distribution pattern,the external load and boundary conditions on bending,buckling and post-buckling characteristics of graded porous structures.The main contents are as follows:1)The shooting method is employed to research the nonlinear mechanical behavior of graded porous material beams.In the analysis,based on the classical beam theory and the concept of surface in physics,the nonlinear bending and post-buckling of the graded porous beam under mechanical load and thermal loading are studied,respectively,The equations of the beam are derived using energy method,and the shooting method is employed to numerically solve the resulting equations.The numerical results obtained herein can be used to analyze the effects of pores distribution pattern,porosity coefficient,coefficient of thermal expansion and boundary conditions on nonlinear mechanical behavior of graded porous material beams.Under mechanical loading,the results show that the bending deflection is increasing and the non-dimensional critical buckling load is decreasing with the increase of pores.Moreover,the results of asymmetric material model are higher than the results of the symmetric material model.Under thermal loading,the porosity distribution has a significant effect on the nonlinear mechanical behavior of graded porous beam.In the case of symmetrical porosity distribution,all exhibit typical bifurcation buckling behavior of the porous beams subjected to both clamped and simple supported boundary condition.In the case of asymmetric porosity distribution,the clamped porous beams still exhibit typical bifurcat ion buckling behavior,transverse displacements occur no matter how small the in-plane thermal loads are,therefore,there is no bifurcation buckling for the beams with simply supported ends.The graded porous properties of materials have a complex influen ce on the thermal buckling behavior of the beam.2)The shooting method is employed to research the nonlinear mechanical behavior of graded porous material circular plate.In the analysis,based on the first order shear deformation plate theory and the concept of surface in physics,governing equations for the nonlinear static response behavior of graded porous circular plate subjected to mechanical load are derived by energy method.Which is degenerated to the basic equation under the classical plate theory,and a shooting method is employed to numerically solve the resulting equation s.The numerical results obtained herein can be used to analyze the effects of pores distribution pattern,porosity coefficient,the external load and boundary conditions on nonlinear mechanical behavior of gradient porous material plate.The porosity has a significant influence on the bending and post-buckling of the circular plate,while the porosity increases,the center deflection of the plate is increases,and the non-dimensional critical buckling load of the circular plate is decreases.The distribution model of porosity has an important influence on the curvature of the porous circular plate and the flexural path,but the change trend is similar.