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Wave Soldering Structure Optimization Simulation of Multi-layer Ceramic Capacitors

Journal of Physics: Conference Series 2020年第3期1650卷

作者： Wei Su Wenhao Luo Junkui Li Renhuai Liu MOE Key lab of Disaster Forecast and Control in Engineering Guangzhou 510632 China. Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research Institute Guangzhou 510610 China. School of Mechanics and Construction Engineering Jinan University Guangzhou 510632 China

In this paper, the thermal analysis and structural analysis of MLCC are carried out by using the commercial finite element software ANSYS. By comparing the thermal-mechanical analysis results of the structural optimization models of different schemes, the optimal optimization scheme is found. The model calculated the time required for MLCC to reach temperature stability considering thermal convection and heat conduction, and obtained the thermal deformation and thermal stress distribution of MLCC element. Based on the analysis results of MLCC original model, the thermal analysis under different wave soldering temperatures was carried out. Based on the simulated transient results, the structure and materials of MLCC key components were optimized. The results provide a basis for the optimal design of MLCC.

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An improved nelder-mead algorithm for optimization problem on structural damage detection 24th

An improved nelder-mead algorithm for optimization problem o...

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24th Australasian Conference on the mechanics of Structures and Materials, ACMSM 2016

作者： Chen, Zepeng Yu, Ling Department of Mechanics and Civil Engineering Jinan University Guangzhou China MOE Key Lab of Disaster Forecast and Control in Engineering Jinan University Guangzhou China

ISBN: (纸本)9781138029934

Structural Damage Detection (SDD) is one of fundamental objectives in the field of structural health monitoring. Usually, the SDD problem can be transformed into an optimal problem by introducing objective functions mathematically. Many methodologies have been developed and achieved great success in the last few decades. However, their calculation efficiency and accuracy are still required to be improved. In this study, an Improved Nelder-Mead (INM) simplex algorithm is proposed for the SDD optimal problem by embedding the Nelder-Mead process into Particle Swarm Optimization (PSO) algorithm. The hybrid algorithm is named PSO-INM. In order to get better results, two filter strategies are proposed based on fitness values and index stability factor. Numerical simulations of a thin-walled hollow simply-supported beam are conducted to assess effectiveness of both PSO-INM and two proposed strategies. The results show that the PSO-INM algorithm and strategies proposed herein are able to locate structural damages as well as to quantify extents of damages with a good noise immunity. Some related issues are discussed as well. © 2017 Taylor & Francis Group, London.

关键词： Structural health monitoring

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Application of sparsity in structural damage detection 8

Application of sparsity in structural damage detection

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8th International Conference on Structural Health Monitoring of Intelligent Infrastructure, SHMII 2017

作者： Chen, Z.P. Yu, L. School of Mechanics and Construction Engineering Jinan University Guangzhou510632 China MOE Key Lab of Disaster Forecast and Control in Engineering Jinan University Guangzhou510632 China

ISBN: (纸本)9781925553055

Structural damage detection (SDD) is one of the major subjects in the field of structural health monitoring (SHM) and various methodologies have been proposed and achieved great accuracy in such field. Inspired by the concept of sparsity, applications of sparsity in SDD are explored in this paper. First of all, an adaptive dictionary is proposed based on intrinsic mode function (IMF), which is utilized to reconstruct compressed acceleration excited by random load. The compressed accelerations are acquired under the application of compressive sensing (CS) technique. Then, as structural damages generally appear locally, SDD problem is characterized by sparsity. Sparse regularization technique is employed to solve SDD by defining two objective functions, to which different sparsity penalty items are introduced. Two iteration procedures inspired by Newton-Gauss algorithm are also presented to solve the problem. Simply-supported beam with different damage degrees are taken as numerical simulations example. The illustrated results show that the proposed method can give an accurate SDD and is robustness to noise. Some related issues are discussed as well. © 2017 International Society for Structural Health Monitoring of Intelligent Infrastrucure. All rights reserved.

关键词： Structural health monitoring

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Output-only structural damage detection based on hard-threshold method: Theoretical study 8

Output-only structural damage detection based on hard-thresh...

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8th International Conference on Structural Health Monitoring of Intelligent Infrastructure, SHMII 2017

作者： Pan, C.D. Yu, L. School of Mechanics and Construction Engineering Jinan University Guangzhou510632 China MOE Key Lab of Disaster Forecast and Control in Engineering Jinan University Guangzhou510632 China

ISBN: (纸本)9781925553055

Structural damage detection (SDD) with a vehicle-bridge system has been widely studied, since traffic excitations contribute to live load components in bridge design code. As an attempt work, this paper aims to propose an output-only SDD method based on hard-threshold strategy with unknown moving forces. Firstly, a transfer matrix is formulated between any two sensors for a healthy bridge structure. Singular value decomposition (SVD) technology is performed for the transfer matrix, and the corresponding singular vectors are used for decomposing two measured responses based on hard-threshold method. Then the decomposed results are used for estimating some singular values. Finally, a damage indicator (DI), which is defined for classifying status of structures, is calculated by comparing the differences between the estimated and true singular values. In order to assess the accuracy and feasibility of the proposed method, a simply-supported bridge subjected to one moving force is taken as an example for numerical simulations. The illustrated results show that the proposed method has a potential ability for solving the SDD problem. Some drawbacks of the proposed method are also discussed as well. © 2017 International Society for Structural Health Monitoring of Intelligent Infrastrucure. All rights reserved.

关键词： Singular value decomposition

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RIP-based subspace projection method for structural damage detection 8

RIP-based subspace projection method for structural damage d...

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8th International Conference on Structural Health Monitoring of Intelligent Infrastructure, SHMII 2017

作者： Luo, Z.W. Yu, L. School of Mechanics and Construction Engineering Jinan University Guangzhou510632 China MOE Key Lab of Disaster Forecast and Control in Engineering Jinan University Guangzhou510632 China

ISBN: (纸本)9781925553055

Structural damage detection (SDD) of large span structures needs to deal with a large number of data produced by thousands of sensors. SDD costs vast amounts of calculating time in a structural health monitoring (SHM) system. To overcome this problem, a new method of SDD is proposed in this paper. A measurement matrix satisfying restricted isometry property (RIP) is used to reduce the numbers of sensitivity equation. It projects the sensitivity matrix into the subspace. In the meantime, it also projects the differences of modal parameters between damaged and undamaged structure into this subspace and reduces the dimensions of differences of modal parameters. Then, the information in lower dimensions can be used for SDD. Finally, due to the sparsity of damage coefficients, sparse regularization method can be used to solve the sensitivity equation in subspace and improve the ill-posedness of SDD. In order to assess capabilities of the proposed method, a plane truss is taken as an example for numerical simulations. Different damage scenarios and the effects of measurement noises on the proposed method are considered. The illustrated results show that the proposed method can effectively detect damage location(s) and quantify damage degrees. © 2017 International Society for Structural Health Monitoring of Intelligent Infrastrucure. All rights reserved.

关键词： Matrix algebra

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R-function theory method for free vibration of slip clamped trapezoidal shallow spherical shell 4th

R-function theory method for free vibration of slip clamped ...

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4th International Conference on Civil, Architectural and Hydraulic engineering, ICCAHE 2015

作者： Li, Shanqing Yuan, Hong MOE Key Laboratory of Disaster Forecast and Control in Engineering Institute of Applied Mechanics Jinan University Guangzhou China

ISBN: (纸本)9781138029163

In this paper, the R-Function Theory (RFT) is applied to solve the free vibration of slip clamped trapezoidal shallow spherical shell. Firstly the fundamental solution of the biharmonic operator, the boundary equation and the R-function are used to construct the quasi-Green’s function. Then the model governing differential equation of the problem is reduced to the Fredholm integral equation of the second kind by Green’s formula. The singularity of the kernel of the integral equation is overcome by choosing a suitable form of the normalized boundary equation by the R-function. A numerical example shows that this method is an effective numerical method. © 2016 Taylor & Francis Group, London.

关键词： Numerical methods

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Theory and calculation of stress transfer between fiber and matrix

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applied Mathematics and mechanics(English Edition) 2015年第6期36卷 815-826页

作者： Jiayu WU Hong YUAN Renhuai LIU MOE Key Laboratory of Disaster Forecast and Control in Engineering Institute of Applied Mechanics Jinan University

For the better use of composites and a deeper insight into the fracture propa- gation and stress transfer of the interface between fiber and matrix, a theoretical solution of closed form is presented with the assumed bilinear local bond-slip law and a parabolic shear stress distribution along the thickness of the matrix. The load-displacement re- lationship and interfacial shear stress are obtained for four loading stages. Finally, the effects of Young＇s modulus of fiber （matrix） and bond length on the performance of the interface are illustrated.

关键词： shear-lag method composite material interfacial mechanics

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Thermal-Structural Coupling Analysis of PCBA System

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IOP Conference Series: Materials Science and engineering 2018年第2期452卷

作者： Wei Su Junhua Zhu Renhuai Liu Zhiyuan He Scienceand Technology on Reliability Physics and Application Technology of Electronic Component Laboratory China Electronic Product Reliability and Environmental Testing Research Institute Guangzhou China MOE Key Lab of Disaster Forecast and Control in Engineering Jinan University Guangzhou China Department of Mechanics and Civil Engineering Jinan University Guangzhou China

In this paper, the thermal and structural analysis of the PCBA system is provided by using the 3-D ANSYS package. The results of thermal and structural analysis for complex and simple model are compared. The paper also describes the deformation analysis of the PCBA system components, and the weak components sensitive to thermal stress are determined though thermal-structual analysis. The results of thermal analysis are helpful to the optimizing overall arrangement design of PCBA system.

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INTERFACIAL BEHAVIOR OF PIPE JOINTS UNDER TORSION LOADS

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Acta Mechanica Solida Sinica 2015年第5期28卷 521-535页

作者： Jun Han Hong Yuan Jiayu Wu MOE Key Lab of Disaster and Control in Engineering Institute of Applied Mechanics Jinan University

The interfacial behavior of pipe joints is studied in this paper. Firstly, through nonlinear fracture mechanics, the analytical expressions of interfacial shear stress and the load- displacement relationship at loaded end of pipe joints under torsion loads are obtained. Thus the shear stress propagation and the debonding process of the whole interface for different bond lengths can be predicted. Secondly, through the analytical solutions, the influences of different bond lengths on the load-displacement curve and the ultimate load are studied. The stress trans- fer mechanism, the interface crack propagation and the ductility behavior of the joints can be explained.

关键词： interface failure mechanism softening debonding torsion pipe joints

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New damage-sensitive feature for structures with bolted joints

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Journal of Physics: Conference Series 2017年第1期842卷

作者： W F Luo L Yu School of Mechanics and Construction Engineering Jinan University Guangzhou 510632 China MOE Key Lab of Disaster Forecast and Control in Engineering Jinan University Guangzhou 510632 China

Compared with riveted and welded joints, bolted joints have advantages of easily dismantled, high load carrying and load-transferring capacity. However, bolted joints are also weaker components of assembled structures. Structural damage detection (SDD) on bolted joints is much required in the field of structural health monitoring (SHM). A new SDD method is proposed for damage identification of structures with bolted joints based on residual error of AR model in time series analysis. Firstly, a new data standardization process is defined to maintain the information of damage location. Then, a new structural damage feature sensitive to structural damage is developed based on the standard deviation of AR model residual errors. To verify the proposed method, a bolted joint structure is designed and fabricated in laboratory, connection damages of structures are simulated by loosening the bolted joints. The acceleration responses of structures with bolted joints under healthy and damage cases are acquired. Finally, the SDD is performed by traditional DSF and the new DSF. The illustrated results show that the proposed method is a hybrid tool for the bolted joint damage detection with the new damage-sensitive feature. In addition, some related issues will be discussed as well.

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