An effective single layered finite element （FE） computational model is proposed to predict the structural behavior of lightweight sandwich panels having two dimensional （2D） prismatic or three dimensional （3D） t...An effective single layered finite element （FE） computational model is proposed to predict the structural behavior of lightweight sandwich panels having two dimensional （2D） prismatic or three dimensional （3D） truss cores. Three different types of cellular core topology are considered： pyramidal truss core （3D）, Kagome truss core （3D） and corrugated core （2D）, representing three kinds of material anisotropy： orthotropic, monoclinic and general anisotropic. A homogenization technique is developed to obtain the homogenized macroscopic stiffness properties of the cellular core. In comparison with the results obtained by using detailed FE model, the single layered computational model can give acceptable predictions for both the static and dynamic behaviors of orthotropic truss core sandwich panels. However, for non-orthotropic 3D truss cores, the predictions are not so well. For both static and dynamic behaviors of a 2D corrugated core sandwich panel, the predictions derived by the single layered computational model is generally acceptable when the size of the unit cell varies within a certain range, with the predictions for moderately strong or strong corrugated cores more accurate than those for weak cores.展开更多
Snap-through phenomenon widely occurs for elastic systems,where the systems lose stability at critical points.Here snapthrough of an elastica under bilateral displacement control at a material point is studied,by rega...Snap-through phenomenon widely occurs for elastic systems,where the systems lose stability at critical points.Here snapthrough of an elastica under bilateral displacement control at a material point is studied,by regarding the whole elastica as two components,i.e.,pinned-clamped elasticas.Specifically,stiffness-curvature curves of two pinned-clamped elasticas are firstly efficiently located based on the second-order mode,which are used to determine the shapes of two components.Similar transformations are used to assemble two components together to form the whole elastica,which reveals four kinds of shapes.One advantage of this way compared with other methods such as the shooting method is that multiple coexisting solutions can be located accurately.O n the load-deflection curves,four branches correspond to four kinds of shapes and first two branches are symmetrical to the last two branches relative to the original point.For the bilateral displacement control,the critical points can only appear at saddle-node bifurcations,which is different to that for the unilateral displacement control.Specifically,one critical point is found on the first branch and two critical points are found on the secondary branch.In addition,the snap-through among different branches can be well explained with these critical points.展开更多
基金The project supported by the National Basic Research Program of China(2006CB601202)the National Natural Science Foundation of China(10328203,10572111,10572119,10632060)+2 种基金the National 111 Project of China(B06024),the Program for New Century Excellent Talents in University(NCET-04-0958)the 0pen Foundation of State Key Laboratory of Structural Analysis of Industrial EquipmentDoctorate Foundation of Northwestern Polytechnical University.
文摘An effective single layered finite element （FE） computational model is proposed to predict the structural behavior of lightweight sandwich panels having two dimensional （2D） prismatic or three dimensional （3D） truss cores. Three different types of cellular core topology are considered： pyramidal truss core （3D）, Kagome truss core （3D） and corrugated core （2D）, representing three kinds of material anisotropy： orthotropic, monoclinic and general anisotropic. A homogenization technique is developed to obtain the homogenized macroscopic stiffness properties of the cellular core. In comparison with the results obtained by using detailed FE model, the single layered computational model can give acceptable predictions for both the static and dynamic behaviors of orthotropic truss core sandwich panels. However, for non-orthotropic 3D truss cores, the predictions are not so well. For both static and dynamic behaviors of a 2D corrugated core sandwich panel, the predictions derived by the single layered computational model is generally acceptable when the size of the unit cell varies within a certain range, with the predictions for moderately strong or strong corrugated cores more accurate than those for weak cores.
基金supported by the National Natural Science Foundation of China(Grants 91648101 and 11972290)the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University(Grant CX201811)the Fundamental Research Funds for the Central Universities(Grant 3102018zy012).
文摘Snap-through phenomenon widely occurs for elastic systems,where the systems lose stability at critical points.Here snapthrough of an elastica under bilateral displacement control at a material point is studied,by regarding the whole elastica as two components,i.e.,pinned-clamped elasticas.Specifically,stiffness-curvature curves of two pinned-clamped elasticas are firstly efficiently located based on the second-order mode,which are used to determine the shapes of two components.Similar transformations are used to assemble two components together to form the whole elastica,which reveals four kinds of shapes.One advantage of this way compared with other methods such as the shooting method is that multiple coexisting solutions can be located accurately.O n the load-deflection curves,four branches correspond to four kinds of shapes and first two branches are symmetrical to the last two branches relative to the original point.For the bilateral displacement control,the critical points can only appear at saddle-node bifurcations,which is different to that for the unilateral displacement control.Specifically,one critical point is found on the first branch and two critical points are found on the secondary branch.In addition,the snap-through among different branches can be well explained with these critical points.
