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
The metal sintering approach offers a costeffective means for the mass-production of open-cell foams from a range of materials, including high-temperature steel alloys, which offer novel mechanical and acoustic proper...The metal sintering approach offers a costeffective means for the mass-production of open-cell foams from a range of materials, including high-temperature steel alloys, which offer novel mechanical and acoustic properties. In a separate experimental study, the mechanical properties of open-celled steel alloy （FeCrA1Y） foams have been characterized under uniaxial compression and shear loading. Compared to predictions from established models, a significant knockdown in material properties was observed. This knockdown was attributed to the presence of defects throughout the microstructure that result from the unique fabrication process. In the present paper, the microstructure of sintered FeCrA1Y foams was modeled by using a finite element （FE） model. In particular, microstructural variations were introduced to a base lattice, and the effects on the strength and stiffness calculated. A range of defects identified under scanning electronic microscope （SEM） imaging were considered including broken ligaments, thickness variations, and pore blockages, which are the three primary imperfections observed in sintered foams. The corresponding levels of defect present in the material were subsequently input into the FE model, with the resulting predictions correlating well with experimental data.展开更多
The mechanical behavior of nanoscale metallic multilayers （NMMs） has attracted much attention from both scientific and practical views. Compared with their monolithic counterparts, the large number of interfaces exi...The mechanical behavior of nanoscale metallic multilayers （NMMs） has attracted much attention from both scientific and practical views. Compared with their monolithic counterparts, the large number of interfaces existing in the NMMs dictates the unique behavior of this special class of structural composite materials. While there have been a number of reviews on the mechanical mechanism of micro- laminates, the rapid development of nanotechnology brought a pressing need for an overview focusing exclusively on a property-based definition of the NMMs, especially their size- dependent microstructure and mechanical performance. This article attempts to provide a comprehensive and up-to-date review on the microstructure, mechanical property and plas- tic deformation physics of NMMs. We hope this review could accomplish two purposes： （1） introducing the basic concepts of scaling and dimensional analysis to scientists and engi- neers working on NMM systems, and （2） providing a better understanding of interface behavior and the exceptional qual- ities the interfaces in NMMs display at atomic scale.展开更多
Advances in laser, microwave and similar technologies have led to recent developments of thermal treatments involving skin tissue. The effectiveness of these treatments is governed by the coupled thermal, mechanical, ...Advances in laser, microwave and similar technologies have led to recent developments of thermal treatments involving skin tissue. The effectiveness of these treatments is governed by the coupled thermal, mechanical, biological and neural responses of the affected tissue： a favorable interaction results in a procedure with relatively little pain and no lasting side effects. Currently, even though each behavioral facet is to a certain extent established and understood, none exists to date in the interdisciplinary area. A highly interdisciplinary approach is required for studying the biothermomechanical behavior of skin, involving bioheat transfer, biomechanics and physiology. A comprehensive literature review pertinent to the subject is presented in this paper, covering four subject areas： （a） skin structure, （b） skin bioheat transfer and thermal damage, （c） skin biomechanics, and （d） skin biothermomechanics. The major problems, issues, and topics for further studies are also outlined. This review finds that significant advances in each of these aspects have been achieved in recent years. Although focus is placed upon the biothermomechanical behavior of skin tissue, the fundamental concepts and methodologies reviewed in this paper may also be applicable for studying other soft tissues.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The project supported by the National Basic Research Program of China(2006CB601202)the National Natural Science Foundation of China(10328203,10572111,10632060)+1 种基金the National 111 Project of China(B06024)the US 0ffice of Naval Research(N000140210117).
文摘The metal sintering approach offers a costeffective means for the mass-production of open-cell foams from a range of materials, including high-temperature steel alloys, which offer novel mechanical and acoustic properties. In a separate experimental study, the mechanical properties of open-celled steel alloy （FeCrA1Y） foams have been characterized under uniaxial compression and shear loading. Compared to predictions from established models, a significant knockdown in material properties was observed. This knockdown was attributed to the presence of defects throughout the microstructure that result from the unique fabrication process. In the present paper, the microstructure of sintered FeCrA1Y foams was modeled by using a finite element （FE） model. In particular, microstructural variations were introduced to a base lattice, and the effects on the strength and stiffness calculated. A range of defects identified under scanning electronic microscope （SEM） imaging were considered including broken ligaments, thickness variations, and pore blockages, which are the three primary imperfections observed in sintered foams. The corresponding levels of defect present in the material were subsequently input into the FE model, with the resulting predictions correlating well with experimental data.
基金supported by the National Natural Science Foundation of China (Grants 51171141, 51271141, and 51471131)the Program for New Century Excellent Talents in University (Grant NCET-11-0431)
文摘The mechanical behavior of nanoscale metallic multilayers （NMMs） has attracted much attention from both scientific and practical views. Compared with their monolithic counterparts, the large number of interfaces existing in the NMMs dictates the unique behavior of this special class of structural composite materials. While there have been a number of reviews on the mechanical mechanism of micro- laminates, the rapid development of nanotechnology brought a pressing need for an overview focusing exclusively on a property-based definition of the NMMs, especially their size- dependent microstructure and mechanical performance. This article attempts to provide a comprehensive and up-to-date review on the microstructure, mechanical property and plas- tic deformation physics of NMMs. We hope this review could accomplish two purposes： （1） introducing the basic concepts of scaling and dimensional analysis to scientists and engi- neers working on NMM systems, and （2） providing a better understanding of interface behavior and the exceptional qual- ities the interfaces in NMMs display at atomic scale.
基金the Overseas Research Studentship (ORS)Overseas Trust Scholarship of Cambridge Universitythe National Natural Science Foundation of China (10572111,10632060)+1 种基金National 111 Project of China (B06024)the National Basic Research Program of China (2006CB601202)
文摘Advances in laser, microwave and similar technologies have led to recent developments of thermal treatments involving skin tissue. The effectiveness of these treatments is governed by the coupled thermal, mechanical, biological and neural responses of the affected tissue： a favorable interaction results in a procedure with relatively little pain and no lasting side effects. Currently, even though each behavioral facet is to a certain extent established and understood, none exists to date in the interdisciplinary area. A highly interdisciplinary approach is required for studying the biothermomechanical behavior of skin, involving bioheat transfer, biomechanics and physiology. A comprehensive literature review pertinent to the subject is presented in this paper, covering four subject areas： （a） skin structure, （b） skin bioheat transfer and thermal damage, （c） skin biomechanics, and （d） skin biothermomechanics. The major problems, issues, and topics for further studies are also outlined. This review finds that significant advances in each of these aspects have been achieved in recent years. Although focus is placed upon the biothermomechanical behavior of skin tissue, the fundamental concepts and methodologies reviewed in this paper may also be applicable for studying other soft tissues.
