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Ultralight X-type lattice sandwich structure (Ⅱ):Micromechanics modeling and finite element analysis

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Science china(Technological Sciences) 2009年第9期52卷 2670-2680页

作者： zhang qiancheng1,CHEN AiPing 2.CHEN ChangQing2.3 & {2. {2.2.1 State key laboratory for Mechanical Behavior of Materials,school of Material Science and Engineering,xi’an Jiaotong University,xi’an 710049,china 2.moe key laboratory for strength and vibration,school of aerospace,xi’an Jiaotong University,xi’an 710049,china 3 Department of Engineering Mechanics,AML,Tsinghua University,Beijing 100084,china State key laboratory for Mechanical Behavior of Materials School of Material Science and Engineering Xi’an Jiaotong University Xi’an China moe key {2. for strength and {2. School of Aerospace Xi’an Jiaotong University Xi’an China Department of Engineering Mechanics AML Tsinghua University Beijing China

The methods of homogenization and finite elements are employed to predict the effective elastic constants and stress-strain responses of a new type of lattice structure,the X-structure proposed by the authors in a companion paper. It is shown that in most cases the predictions by the equivalent homogenization theory agree well with the experimental and 3-dimensional finite element calculated results. The theoretical and numerical study supports the argument that the X-structure is superior to the pyramid lattice structure in terms of mechanical strength.

关键词： sandwich panel lattice structure equivalent homogenization finite element model

Thermoelastic properties of sandwich materials with pin-reinforced foam cores

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Science china(Technological Sciences) 2008年第12期51卷 2059-2074页

作者： lu tianjian1,LIU Tao2.3 & DENG ZiChen2.4 1 {2. key laboratory of {2. and vibration,school of aerospace,xi’an Jiaotong University,xi’an 710049,china 2.Department of Engineering Mechanics,Northwestern Polytechnical University,xi’an 710072.china 3 Department of Engineering,University of Cambridge,Cambridge CB2.1PZ,UK 4 State key laboratory of Structural Analysis of Industrial Equipment,Dalian University of Technology,Dalian 11602.,china moe key {2. of strength and {2. School of Aerospace Xi’an Jiaotong University Xi’an China Department of Engineering Mechanics Northwestern Polytechnical University Xi’an China Department of Engineering University of Cambridge Cambridge UK State key laboratory of Structural Analysis of Industrial Equipment Dalian University of Technology Dalian China

Pin-reinforced foam is a novel type of sandwich core materials formed by inserting pins(trusses) into a foam matrix to create a truss-like network reinforced foam *** loading,the pins deform predominantly by local stretching whilst the deformation of foam is governed by local *** paper presents a theoretical study on the thermoelasticity of pin-reinforced foam sandwich *** calculate the effective thermoelastic properties of pin-reinforced foam cores,the energy-based homogenization approach is employed to develop a micromechanics-based model,calibrated by the existing experimental *** is found that the stiffness of the sandwich core is mainly governed by pin reinforcements:the foam matrix contributes little to sandwich *** with traditional foam cores without pin reinforcements,the changes in inplane thermal expansion coefficients are not vigorous as a result of pin reinforcements,while the through-thickness thermal expansion coefficient changes *** is also demonstrated that it is possible to design materials with zero or negative thermal expansion coefficients under such a context.

关键词： sandwich panel pin reinforcement analytical solutions homogenization thermoelasticity thermal expansion

BIOTHERMOMECHANICS OF SKIN TISSUES

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BIOTHERMOMECHANICS OF SKIN TISSUES

EXPERIMENTAL AND SIMULATED COMPRESSIVE PROPERTIES OF WORK-HARDENED X-TYPE LATTICE TRUSS STRUCTURES

庆祝中国力学学会成立50周年暨中国力学学会学术大会’2.07

作者： lu tianjian ({2. key laboratory of {2. and vibration,school of aerospace,xi’an Jiaotong University,xi’an 710049,china)

Biothermomechanics of skin is highly interdisciplinary,involving bioheat transfer,burn damage, biomechanics and *** heating,thermally induced mechanical stress arises due to the thermal denaturation of collagen,result...

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Acta Mechanica Solida Sinica 2012年第2期25卷 111-116页

作者： qiancheng zhang {2. lu moe key {2. of strength&{2. School of AerospaceXi'an Jiaotong UniuersityXi'an 710049China

The expanded metal sheets were folded with 11% work-hardening. These were sub- sequently used with resistance welding to construct X-type lattice truss sandwich panels having a core relative density of 0.17. The sandwich panels were tested in uniaxial compression and, for comparison, the method of finite elements was employed to simulate the measured compressive stress-strain curves. The peak compressive strength was 32. higher than that of pyramidal core sandwiches. The enhanced mechanical properties of the work-hardened X-Type lattice structures mainly originate from the contribution of straight struts with low degree of curvature and work hardening, rather than the two-dimensional staggered nodes.

关键词： sandwichs work hardening resistance welding X-type core

Sound transmission across lightweight all-metallic sandwich panels with corrugated cores

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Chinese Journal of Acoustics 2009年第3期28卷 231-243页

作者： xiN Fengxian lu tianjian CHEN Changqing moe key {2. for strength and {2. School of Aerospace Xi'an Jiaotong University Xi'an 710049

The transmission of sound through all-metallic sandwich panels with corrugated cores is investigated using the space-harmonic method. The sandwich panel is modeled as two parallel panels connected by uniformly distributed translational springs and rotational springs, with the mass of the core sheets taken as lumped mass. Based on the periodicity of the panel structure, a unit cell model is developed to provide the effective translational and rotational stiffness of the core. To check the validity of the model, it is used first to study the sound insulation properties of double-panel structures with air cavity, and the analytical predictions agree well with existing experimental data. The model is then employed to quantify the influence of sound incidence angle and the inclination angle between facesheet and core sheet on sound transmission loss （STL） across sandwich panels with corrugated cores. The results show that the inclination angle has a significant effect on STL and it is possible to avoid STL dips by altering the inclination angle. Moreover, it is found that sandwich panels with corrugated cores are more suitable for the insulation of sound waves having small incidence angles.

关键词： with 细胞模型集中质量面板结构传输损耗夹芯板 STL 空间谐波

Ultralight X-type lattice sandwich structure(I):Concept,fabrication and experimental characterization

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Science china(Technological Sciences) 2009年第8期52卷 2147-2154页

作者： zhang qiancheng HAN YunJie CHEN ChangQing {2. {2. State key laboratory for Mechanical Behavior of Materials School of Material Science and EngineeringXi’an Jiaotong UniversityXi’an 710049China moe key {2. for strength and {2. School of AerospaceXi’an Jiaotong UniversityXi’an 710049China Department of Engineering Mechanics AMLTsinghua UniversityBeijing 100084China

A new type of ultra-lightweight metallic lattice structure (named as the X-type structure) is reported. This periodic structure was formed by two groups of staggered struts in the traditional pyramid structure, and fabricated by folding expanded metal sheet along rows of offset nodes and then brazing the folded structure (as the core) with top and bottom facesheets to form sandwich panels. The out-of-plane compressive and shear properties of the X-type lattice sandwich structure were investigated experimentally and compared to those of the sandwich having a pyramidal truss core. It is found that the formation of the 2.dimensional staggered nodes can effectively make the X-type structure more resistant to inelastic and plastic buckling under both compression and shear loading than the pyramidal lattice truss. Obtained results show that the compressive and shear peak strengths of the X-type lattice structure are about 30% higher than those of the pyramidal lattice truss having the same relative density.

关键词： sandwich panel lattice structure X-type structure brazing plastic yielding

Development of multifunctional lightweight cellular metals through interdisciplinary efforts

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Chinese Science Bulletin 2009年第20期54卷 3844-3846页

作者： lu Tian Jian zhang {2. moe key {2. for strength and {2. School of Aerospace Xi'an Jiaotong University Xi'an 710049 China State key laboratory for Mechanical Behavior of Materials School of Material Science and Engineering Xi'an Jiaotong University Xi'an 710049 China

In spite of her phenomenal economic achievement since the historically imperative implementation of the 'open door' policy in

关键词：金属蜂窝多学科多功能轻质保护环境能源资源金融危机工业化

Characteristics of annular impinging jets with/without swirling flow by short guide vanes

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Science china(Technological Sciences) 2011年第3期54卷 749-757页

作者： YANG HuiQun KIM TongBeum lu tianjian moe key {2. for strength and {2. School of Aerospace Xi'an Jiaotong University Xi'an 710049 China school of Mechanical Industrial and Aeronautical Engineering University of Witwatersrand Private Bag 3 Wits 2050 Johannesburg South Africa

Annular jets impinging on a uniformly heated flat plate with or without swirling flow by short guide vanes are experimentally characterized. With the Reynolds number fixed at a relatively low value, the variation of jet flow structures with impinging distance is characterized using the technique of particle image velocimetry (PIV). Correspondingly, the distributions of wall pressure and heat transfer on the plate are measured. At sufficiently large impinging distances, without swirling flow, the obtained flow and wall pressure/heat transfer data are consistent with the classical observation for a conventional annular impinging jet, showing the transition from annular impinging jet flow to single circular impinging jet-like flow. In contrast, no such transition occurs in the presence of flow turning by short guide vanes. At short and intermediate impinging distances, flow turning causes more non-uniform distributions of wall pressure and heat transfer on the target plate and the local heat transfer rates higher than those of the conventional annular jet. This is attributed to the vortical flow structures shed and convected downstream from the short guide vanes. In sharp contrast, at large impinging distances, the larger momentum loss due to flow turning results in lower heat transfer rates on the plate.

关键词： annular impinging jet flow structure swirling flow guide vanes wall heat transfer wall pressure

Bleustein-Gulyaev waves in a functionally graded piezoelectric material layered structure

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Science china(Physics,Mechanics & Astronomy) 2009年第4期52卷 613-625页

作者： CAO xiaoshan JIN Feng WANG ZiKun lu tianjian moe key {2. for strength and {2. School of AerospaceXi’an Jiaotong UniversityXi’an 710049China

This work presents a theoretical study of the propagation behavior of Bleustein-Gulyaev waves in a layered structure consisting of a functionally graded piezoelectric material(FGPM) layer and a transversely isotropic piezoelectric substrate. The influence of the graded variation of FGPM coefficients on the dispersion relations of Bleustein-Gulyaev waves in the layered structure is investigated. It is demonstrated that,for a certain frequency range of Bleustein-Gulyaev waves,the mechanical perturbations of the particles are restricted in the FPGM layer and the phase velocity is independent of the electrical boundary conditions at the free surface. Results presented in this study can not only provide further insight on the electromechanical coupling behavior of surface waves in FGPM layered structures,but also lend a theoretical basis for the design of high-performance surface acoustic wave(SAW) devices.

关键词： Bleustein-Gulyaev waves functionally graded piezoelectric material electro-mechanical coupling factor surface acoustic wave device