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Discussion on electromagnetic crack face boundary conditions for the fracture mechanics of magneto-electro-elastic materials

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Acta Mechanica Sinica 2006年第3期22卷 233-242页

作者： baolin wang Jiecai Han Center for Composite Materials Harbin Institute of Technology Harbin 150001 China

This paper discusses electromagnetic boundary conditions on crack faces in magneto- electroelastic materials, where piezoelectric, piezomagnetic and magnetoelectric effects are coupled. A notch of finite thickness in these materials is also addressed. Four idealized electromagnetic boundary conditions assumed for the crack-faces are separately investigated, i.e. （a） electrically and magnetically impermeable （crack-face）, （b） electrically impermeable and magnetically permeable, （c） electrically permeable and magnetically impermeable, and （d） electrically and magnetically permeable. The influence of the notch thickness on important parameters, such as the field intensity factors, the energy release rate at the notch tips and the electromagnetic fields inside the notch, are studied and the results are obtained in closed-form. Results under different idealized electromagnetic boundary conditions on the crack-face are compared, and the applicability of these idealized assumptions is discussed.

关键词： Fracture mechanics Magnetoelectroelastic materials Boundary conditions Notch Crack

Fracture mechanics associated with non-classical heat conduction in thermoelastic media

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Science China(Physics,Mechanics & Astronomy) 2012年第3期55卷 493-504页

作者： wang baolin HAN JieCai Graduate School at Shenzhen and Center for Composite Materials Harbin Institute of TechnologyHarbin 150001China School of Materials Science and Engineering The University of New South WalesSydneyNSW 2052Australia

This paper studies the thermoelastic fracture in a solid under non-classical Fourier heat *** temperature field and the associated thermal stresses are solved by the dual integral equation *** thermally insulated crack and heated crack are *** is found that the crack tip thermal stress is singular and can be expressed in terms of the thermal stress intensity factor in a *** results show that the crack considerably amplifies the local thermal stresses,confirming the significance of the effect of non-classical heat conduction on the thermoelastic fracture mechanics of materials.

关键词： thermal stresses fracture mechanics non-classical heat conduction

Anti-plane pull-out of a rigid line inclusion from an elastic medium

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Applied Mathematics and Mechanics(English Edition) 2023年第5期44卷 809-822页

作者： Yansong wang baolin wang Youjiang CUI Kaifa wang Harbin Institute of Technology Shenzhen Campus Harbin Institute of TechnologyHarbin 150001China

The transient and static anti-plane problem of a rigid line inclusion pulled out from an elastic medium is *** singular integral equation method is used to solve the stress *** the static load,the stress intensity factor(SIF)at the inclusion tips increases with the medium *** problem becomes equivalent to an inclusion in a medium with an infinite length when the length of the medium is 3.5times longer than that of the ***,under the transient load,the maximum value of the SIF occurs when the medium length is about two times the inclusion ***,the relation between the pull-out force and the anti-plane displacement is *** conclusions are useful in guiding the design of fiber reinforced composite materials.

关键词： pull-out rigid line inclusion anti-plane stress intensity factor(SIF) stress singularity

A MOVING CRACK IN A NONHOMOGENEOUS MATERIAL STRIP

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Acta Mechanica Solida Sinica 2006年第3期19卷 223-230页

作者： wang baolin Han Jiecai Center for Composite Materials Harbin Institute of Technology Harbin 150001 China

This paper considers an anti-plane moving crack in a nonhomogeneous material strip of finite thickness. The shear modulus and the mass density of the strip are considered for a class of functional forms for which the equilibrium equation has analytical solutions. The problem is solved by means of the singular integral equation technique. The stress field near the crack tip is obtained. The results are plotted to show the effect of the material non-homogeneity and crack moving velocity on the crack tip field. Crack bifurcation behaviour is also discussed. The paper points out that use of an appropriate fracture criterion is essential for studying the stability of a moving crack in nonhomogeneous materials. The prediction whether the unstable crack growth will be enhanced or retarded is strongly dependent on the type of the fracture criterion used. Based on the analysis, it seems that the maximum ＇anti-plane shear＇ stress around the crack tip is a suitable failure criterion for moving cracks in nonhomogeneous materials.

关键词： nonhomogeneous materials fracture mechanics moving crack

Influence of residual surface stress on the fracture of nanoscale piezoelectric materials with conducting cracks

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Science China(Physics,Mechanics & Astronomy) 2014年第2期57卷 280-285页

作者： NAN HaiShun wang baolin Graduate School at Shenzhen Harbin Institute of Technology

In this paper,we analyze the stress and electric field intensity factors affected by residual surface stress for conducting cracks in piezoelectric *** problem is reduced to a system of non-linear singular integral equations,whose solution is determined by iteration *** results indicate that the residual surface stress can significantly alter the crack tip fields at nanometer length *** to the residual surface stress,281he electric field can produce stress around crack *** suggests a strong electromechanical coupling crack tip field for nanoscale piezoelectric *** a finding is considerably different from the classical fracture mechanics results.A transit electric field to stress load ratio is identified,for which influences of residual surface stresses *** research is useful for the applications of nanoscale piezoelectric devices.

关键词： fracture mechanics residual surface stress piezoelectric materials nanomechanics conducting cracks

Biodegradation of pyrene by Phanerochaete chrysosporium and enzyme activities in soils:Effect of SOM,sterilization and aging

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Journal of Environmental Sciences 2014年第5期26卷 1135-1144页

作者： Cuiping wang Hongwen Sun Haibin Liu baolin wang MOE Key Laboratory of Pollution Processes and Environmental Criteria College of Environmental Science and Engineering Nankai University

The impacts of soil organic matter （SOM）, aging and sterilization on the production of lignin peroxidase （LIP） and manganese peroxidase （MnP） by Phanerochaete chrysosporium during the biodegradation of pyrene in soils were investigated. The biodegradation of pyrene by P. chrysosporium decreased with increasing SOM content, whereas the maximum activities of LiP and MnP increased, which indicates that SOM outweighed pyrene in controlling enzyme production. Sterilization enhanced the degradation of pyrene due to the elimination of competition from indigenous microbes, whereas aging led to a reduction in the degradation of pyrene primarily through changes in its sorbed forms. Both sterilization and aging could reduce SOM content and alter its structure, which also influenced the bioavailability of pyrene and the enzyme activity. The sterilization and aging processes caused changes in the degradation of pyrene, and the enzyme activities were greater in soils with high SOM contents. MnP was related to the degradation of pyrene to a greater extent, whereas LiP was more related to the decomposition of SOM.

关键词： biodegradation Phanerochaete chrysosporium enzyme activities soil organic matter sterilization aging

Vibration analysis of piezoelectric sandwich nanobeam with flexoelectricity based on nonlocal strain gradient theory

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Applied Mathematics and Mechanics(English Edition) 2020年第6期41卷 859-880页

作者： Shan ZENG Kaifa wang baolin wang Jinwu WU Jiangxi Key Laboratory of Micro Aeroengine School of Aircraft EngineeringNanchang Hangkong UniversityNanchang 330063China Graduate School at Shenzhen Harbin Institute of TechnologyHarbin 150001China School of Engineering Western Sydney UniversityPenrithNSW 2751Australia

A nonlocal strain gradient theory(NSGT) accounts for not only the nongradient nonlocal elastic stress but also the nonlocality of higher-order strain gradients,which makes it benefit from both hardening and softening effects in small-scale *** this study, based on the NSGT, an analytical model for the vibration behavior of a piezoelectric sandwich nanobeam is developed with consideration of flexoelectricity. The sandwich nanobeam consists of two piezoelectric sheets and a non-piezoelectric core. The governing equation of vibration of the sandwich beam is obtained by the Hamiltonian principle. The natural vibration frequency of the nanobeam is calculated for the simply supported(SS) boundary, the clamped-clamped(CC) boundary, the clamped-free(CF)boundary, and the clamped-simply supported(CS) boundary. The effects of geometric dimensions, length scale parameters, nonlocal parameters, piezoelectric constants, as well as the flexoelectric constants are discussed. The results demonstrate that both the flexoelectric and piezoelectric constants enhance the vibration frequency of the *** nonlocal stress decreases the natural vibration frequency, while the strain gradient increases the natural vibration frequency. The natural vibration frequency based on the NSGT can be increased or decreased, depending on the value of the nonlocal parameter to length scale parameter ratio.

关键词： piezoelectric nanobeam sandwich structure flexoelectric nonlocal strain gradient theory(NSGT)

Galerkin-based quasi-smooth manifold element(QSME)method for anisotropic heat conduction problems in composites with complex geometry

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Applied Mathematics and Mechanics(English Edition) 2024年第1期45卷 137-154页

作者： Pan wang Xiangcheng HAN Weibin WEN baolin wang Jun LIANG School of Civil Engineering Central South UniversityChangsha 410083China Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China School of Science Harbin Institute of TechnologyShenzhen 518055Guangdong ProvinceChina

The accurate and efficient analysis of anisotropic heat conduction problems in complex composites is crucial for structural design and performance evaluation. Traditional numerical methods, such as the finite element method(FEM), often face a trade-off between calculation accuracy and efficiency. In this paper, we propose a quasi-smooth manifold element(QSME) method to address this challenge, and provide the accurate and efficient analysis of two-dimensional(2D) anisotropic heat conduction problems in composites with complex geometry. The QSME approach achieves high calculation precision by a high-order local approximation that ensures the first-order derivative *** results demonstrate that the QSME method is robust and stable, offering both high accuracy and efficiency in the heat conduction analysis. With the same degrees of freedom(DOFs), the QSME method can achieve at least an order of magnitude higher calculation accuracy than the traditional FEM. Additionally, under the same level of calculation error, the QSME method requires 10 times fewer DOFs than the traditional FEM. The versatility of the proposed QSME method extends beyond anisotropic heat conduction problems in complex composites. The proposed QSME method can also be applied to other problems, including fluid flows, mechanical analyses, and other multi-field coupled problems, providing accurate and efficient numerical simulations.

关键词： anisotropic heat conduction quasi-smooth manifold element(QSME) composite with complex geometry numerical simulation finite element method(FEM)

Signal Processing of the Area-Target for a Short-Range Radar

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Journal of Systems Engineering and Electronics 2000年第2期11卷 73-80页

作者： Li, Guolin wang, baolin Shi, Jusheng Naval Aeronautical Engineering Acad Yantai China

This paper presents a multi-component frequency modulation (FM) signal model for short-range radar based on the multi-points scattering model of a target, and proves that the method of computing the instantaneous frequency of single frequency is not suitable to the multi-component signal. The method of TLS-ESPRIT combining the mathematical statistics is presented for obtaining the multi-component signal instantaneous frequency (IF). The computer simulation has shown that the method has the high accuracy for measuring the distance.

关键词： Computer simulation Electromagnetic wave scattering Frequency modulation Mathematical models Statistics