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bi-material strip based temperature sensor design and optimization through thermo-mechanical multi-physics modeling

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International Journal of Smart and Nano materials 2019年第1期10卷 1-10,I0001页

作者： Baobao Tang Sarah Kathryn Collings Hai Xiao Huijuan Zhao Department of Mechanical Engineering Clemson UniversityClemsonSCUSA Holcombe Department of Electrical and Computer Engineering Clemson UniversityClemsonSCUSA

With the capability of additive manufacturing,complex structures are easily fabricated to achieve various design *** this work,a bi-material strip temperature sensor with complex periodic pattern design is purposed and investigated through both the analytical modeling and multi-physics finite element *** design patterns are considered:standard,E-shape and *** the standard solid strip design,the curvature of the bi-material strip under temperature variation is in a linear relationship with the coefficient of thermal expansion(CTE)difference,but in a reciprocal relationship with the strip *** curvature of the bi-material strip depends on the Young’s modulus ratio and layer thickness ratio of the two materials,but is independent of the magnitude of the materials’Young’s *** on analytical derivation and numerical validation,the optimized design parameters can be *** to S-shape pattern design,E-shape pattern design can significantly increase the temperature sensitivity of the bi-material *** analytical prediction of the E-shape pattern’s temperature sensitivity is introduced and *** work proves the concept that new design space becomes available with the capability of additive manufacturing,and provides the general design guideline for a bi-material strip based temperature sensor with possible design patterns.

关键词： bi-material temperature sensing optimization finite element analysis

Analysis of stress intensity factor in orthotropic bi-material mixed interface crack

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Applied Mathematics and Mechanics(English Edition) 2014年第10期35卷 1271-1292页

作者：赵文彬张雪霞崔小朝杨维阳 School of Applied Sciences Taiyuan University of Science and Technology

Adopting the complex function approach, the paper studies the stress intensity factor in orthotropic bi-material interface cracks under mixed loads. With con- sideration of the boundary conditions, a new stress function is introduced to transform the problem of bi-material interface crack into a boundary value problem of partial dif- ferential equations. Two sets of non-homogeneous linear equations with 16 unknowns are constructed. By solving the equations, the expressions for the real bi-material elastic constant εt and the real stress singularity exponents λt are obtained with the bi-material engineering parameters satisfying certain conditions. By the uniqueness theorem of limit, undetermined coefficients are determined, and thus the bi-material stress intensity factor in mixed cracks is obtained. The bi-material stress intensity factor characterizes features of mixed cracks. When orthotropic bi-materials are of the same material, the degenerate solution to the stress intensity factor in mixed bi-material interface cracks is in complete agreement with the present classic conclusion. The relationship between the bi-material stress intensity factor and the ratio of bi-material shear modulus and the relationship be- tween the bi-material stress intensity factor and the ratio of bi-material Young＇s modulus are given in the numerical analysis.

关键词： interface crack stress intensity factor bi-material orthotropic complexvariable method

Power Flow Response Based Dynamic Topology Optimization of bi-material Plate Structures

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Chinese Journal of Mechanical Engineering 2013年第3期26卷 620-628页

作者： XUE Xiaoguang LI Guoxi XIONG Yeping GONG Jingzhong School of Mechatronic Engineering and Automation National University of Defense Technology Faculty of Engineering and the Environment University of Southampton

Work on dynamic topology optimization of engineering structures for vibration suppression has mainly addressed the maximization of eigenfrequencies and gaps between consecutive eigenfrequencies of free vibration, minimization of the dynamic compliance subject to forced vibration, and minimization of the structural frequency response. A dynamic topology optimization method of bi-material plate structures is presented based on power flow analysis. Topology optimization problems formulated directly with the design objective of minimizing the power flow response are dealt with. In comparison to the displacement or velocity response, the power flow response takes not only the amplitude of force and velocity into account, but also the phase relationship of the two vector quantities. The complex expression of power flow response is derived based on time-harmonic external mechanical loading and Rayleigh damping. The mathematical formulation of topology optimization is established based on power flow response and bi-material solid isotropic material with penalization(SIMP) model. Computational optimization procedure is developed by using adjoint design sensitivity analysis and the method of moving asymptotes(MMA). Several numerical examples are presented for bi-material plate structures with different loading frequencies, which verify the feasibility and effectiveness of this method. Additionally, optimum results between topological design of minimum power flow response and minimum dynamic compliance are compared, showing that the present method has strong adaptability for structural dynamic topology optimization problems. The proposed research provides a more accurate and effective approach for dynamic topology optimization of vibrating structures.

关键词： dynamic topology optimization power flow response bi-material plate structures

Topology optimization of piezoelectric bi-material actuators with velocity feedback control

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Frontiers of Mechanical Engineering 2019年第2期14卷 190-200页

作者： Mariana MORETTI Emilio C.N.SILVA School of Engineering University of Sao PauloSao PauloSP 05508-030Brazil

In recent years,the new technologies and discoveries on manufacturing materials have encouraged researchers to investigate the appearance of material properties that are not naturally *** featuring a specific stiffness,or structures that combine non-structural and stmctural functions are applied in the aerospace,electronics and medical industry ***,structures designed for dynamic actuation with reduced vibration response are the focus of this *** bi-material and multifunctional concepts are considered for the design of a controlled piezoelectric actuator with vibration suppression by means of the topology optimization method(TOM).The bi-material piezoelectric actuator(BPEA)has its metallic host layer designed by the TOM,which defines the structural function,and the electric function is given by two piezo-ceramic layers that act as a sensor and an actuator coupled with a constant gain active velocity feedback control(AVFC).The AVFC,provided by the piezoelectric layers,affects the structural damping of the system through the velocity state variables readings in time *** dynamic equation analyzed throughout the optimization procedure is fully elaborated and *** dynamic response for the rectangular fbur-noded finite element analysis is obtained by the Newmark's time-integration method,which is applied to the physical and the adjoint systems,given that the adjoint formulation is needed for the sensitivity analysis.A gradient-based optimization method is applied to minimize the displacement energy output measured at a predefined degree-of-freedom of the BPEA when a transient mechanical load is *** are obtained for different control gain values to evaluate their influence on the final topology.

关键词： topology optimization method bi-material piezoactuator active velocity feedback control timedomain transient analysis host structure design vibration suppression

Calculation of thermal neutron albedo for mono-material and bi-material reflectors

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Nuclear Science and Techniques 2018年第9期29卷 185-191页

作者： Sara Azimkhani Farhad Zolfagharpour Farhood Ziaie Department of Physics University of Mohaghegh Ardabili Radiation Application Research School Nuclear Science & Technology Research Institute

Thermal neutron albedo has been investigated for different thicknesses of mono-material and bi-material reflectors. An equation has been obtained for a bi-material reflector by considering the neutron diffusion equation. The bi-material reflector consists of binary combinations of water, graphite, lead, and polyethylene. An experimental measurement of thermal neutron albedo has also been conducted for mono-material and bi-material reflectors by using a^(241) Am–Be(5.2 Ci) neutron source and a BF3 detector. The maximum value of thermal neutron albedo was obtained for a polyethylene–water combination(0.95 ± 0.02).

关键词： Neutron current bi-material reflector Thermal neutron albedo BF3 detector Reflection Diffusion equation

Crack-Tip Stress Analysis at a bi-material Interface by Photoelastic, Isopachic and FEA

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materials Sciences and Applications 2011年第8期2卷 1027-1032页

作者： George A. Papadopoulos Elen B. Bouloukou Elen G. Papadopoulou National Technical University of Athens Department of Engineering Science Section of Mechanics Zografou campus National Technical University of Athens Department of Mining Engineering and Metallurgy Laboratory of physical Metallurgy

The paper investigates the stress state at the bi-material interface crack-tip by the Photoelastic and Isopachic methods and the Finite Element Analysis (FEA). The principal stresses at the bi-material interface crack-tip are theoretically determined using the combination photoelastic and isopachic fringes. The size and the shape of crack-tip isochro-matic and isopachic fringes, at a bi-material interface under static load, are studied. When the crack-tip, which is perpendicular to interface, is placed at the interface of the bi-material, the isochromatic and the isopachic fringes depend on the properties of the two materials. Thus, the isochromatic and the isopachic fringes are divided into two branches, which present a jump of values at the interface. The size of the two branches mainly depends on the elastic modulus and the Poisson’s ratio of the two materials. From the combination of the isochromatic and the isopachic fringes, the principal stresses σ1 and σ2 can be estimated and the contour curves around the crack-tip can be plotted. For the FEA analysis, the program ANSYS 11.0 was used. The bi-material cracked plates were made from Lexan (BCBA) and Plexiglas (PMMA).

关键词： Crack bi-material Photoelasticity Isochromatic Isopachic FEA

Interface microstructure evolution and bonding strength of TC11/c-TiA l bi-materials fabricated by laser powder deposition

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Rare Metals 2016年第6期35卷 456-462页

作者： Zhi-Jun Xu Yong-Zhong Zhang Ming-Kun Liu Xin-Yong Gong Center for Composites General Research Institute for Nonferrous Metals Beijing 100088 China

Laser powder deposition was applied to fabricate the Ti-6.5Al-3.5Mo-1.5Zr-0.3Si （wt%）/Ti-47Al- 2Cr-2Nb-0.2W-0.15B （at%） bi-material system. The asdeposited TC11 alloy shows a basket-wave-like morphology while the as-deposited y-TiAl alloy consists of fully α2/γ lamellar microstructures. Regarding the thermal mismatch between TC11 and γ-TiAl during processing, the interface microstmcture evolution was concerned. The transformation pathway was illustrated. It is found that the content changes of Al elements and β-stabilizers Mo, Cr, and Nb are responsible for the evolution of microstructures at the interface. The fracture surfaces are located at the y-TiAl side. The bi-material shows a brittle-fracture manner, with the ultimate tensile strength of 560 MPa.

关键词： Laser powder deposition TC11 titanium alloy γ-TiAl alloy bi-material Interface

METHOD TO CALCULATE STRESS INTENSITY FACTOR OF V-NOTCH IN bi-materialS

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Acta Mechanica Solida Sinica 2008年第4期21卷 337-346页

作者： Youtang Li Ming Song Key Laboratory of Digital Manufacturing Technology and Application Ministry of Education Lanzhou University of Technology Lanzhou 730050 China College of Meehano-Electronic Engineering Lanzhou University of Technology Lanzhou 730050 China

Based on Zak＇s stress function, the eigen-equation of stress singularity ofbi-materials with a V-notch was obtained. A new definition of stress intensity factor for a perpendicular interfacial V-notch of bi-material was put forward. The effects of shear modulus and Poisson＇s ratio of the matrix material and attaching material on eigen-values were analyzed. A generalized expression for calculating/（i of the perpendicular V-notch of bi-materials was obtained by means of stress extrapolation. Effects of notch depth, notch angle and Poisson＇s ratio of materials on the singular stress field near the tip of the V-notch were analyzed systematically with numerical simulations. As an example, a finite plate with double edge notches under uniaxial uniform tension was calculated by the method presented and the influence of the notch angle and Poisson＇s ratio on the stress singularity near the tip of notch was obtained.

关键词： bi-material V-notch eigen-equation stress intensity factor finite element method

Structural evolution of mesoporous graphene/LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2) composite cathode for Li-ion battery

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Rare Metals 2021年第3期40卷 521-528页

作者： Wen-Jie Liu Xian-Zhong Sun Xiong Zhang Chen Li Kai Wang Wen Wen Yan-Wei Ma Institute of Electrical Engineering Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100190China Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201204China

Layered LiMO_(2)(M=Ni,Co,and Mn) is a type of promising cathode materials for high energy density and high work voltage lithium-ion ***,the poor rate performance and low power density hinder its further *** capacity fade is related to the structural transformation in the layered LiMO_(2).In this work,the structural changes of bi-material cathode composed of mesoporous graphene and layered LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2)(NCM) were studied via in situ X-ray diffraction(XRD).During different C-rate charge-discharge test at the voltage range of 2.5-4.1 V,the composite cathode of NCM-graphene(NCM-G) reveals better rate performances than pure NCM *** NCM-G composite electrode displays a higher rate capability of 76.7 mAh·g^(-1) at 5 C rate,compared to the pure NCM cathode of 69.8 mAh·g^(-1)discharge *** in situ XRD results indicate that a reversible phase transition from hexagonal H1 to hexagonal H2 occurs in layered NCM material during 1 C chargedischarge *** the current increasing to 2 C/5 C,the structure of layered NCM material for both electrodes reveals few changes during charge and discharge processes,which indicates the less utilization of NCM component at high ***,the improved rate performance for bi-material electrode is attributed to the highly conductive mesoporous graphene and the synergistic effect of mesoporous graphene and NCM material.

关键词： LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2)(NCM) Mesoporous graphene bi-material In situ X-ray diffraction(XRD) Structural evolution