复合材料中压电螺型位错与含刚性核夹杂的电弹干涉

为了研究压电复合材料中位于基体的压电螺型位错与含共焦椭圆导电刚性核椭圆夹杂的电弹相互作用, 基于复变函数方法, 获得了基体和夹杂区域的精确级数形式解析解。运用广义Peach-Koehler公式, 导出了作用在位错上像力的解析表达式。在此基础上讨论了椭圆刚性核和材料电弹特性对位错像力以及位错平衡位置的影响规律, 同时讨论了压电夹杂和弹性基体的复合情况。结果表明: 椭圆刚性核对位错有着明显的排斥作用, 可以增强硬夹杂对位错的排斥, 减弱软夹杂对位错的吸引; 对于软夹杂, 在界面附近位错存在一个不稳定的平衡位置; 在基体和夹杂的界面上, 像力迅速增大; 当夹杂的剪切模量远小于基体时, 界面附近不会出现位错的平衡位置。     

磁电弹双材料条中螺位错与界面边裂纹的相互作用

研究半无限长磁电弹双材料条中螺位错与界面边裂纹的相互作用。基于镜像原理和保角变换方法,得到了弹性场、电场和磁场的解析解,给出了应力、电位移、磁感应强度、应力强度因子以及像力的显函表达式。以压电-压磁双材料条形介质为例,分析了应力场、电位移和磁感应强度的分布特性,讨论了几何参数、压电和压磁效应对应力强度因子和像力的影响。     

压电螺位错与圆夹杂的电弹相互作用

研究压电材料中压电螺位错与圆夹杂的相互作用问题，分析基体与夹杂的相对刚度以及压电效应对作用于位错上像力的影响，得到了新的相互作有机理。     

含不完美界面的磁电复合材料倾斜裂纹问题

研究了含非完美界面的双层压电/压磁复合材料中压电相存在一个倾斜于界面的Ⅲ型裂纹问题。采用弹簧型耦合界面模型模拟非完美界面,运用Fourier积分变换法将裂纹面条件转化为奇异积分方程,并使用Lobatto-Chebyshev方法数值求解了裂纹尖端应力强度因子（SIF）。详细地研究了裂纹尖端SIF与界面参数、压电/压磁材料参数和材料的层厚、裂纹的倾斜角、裂纹与界面的距离等几何参数的关系。结果表明：力学不完美性可以独立地增大SIF,而磁学、电学不完美性只有与力学不完美性耦合时才会减小SIF;力学-电学、力学-磁学不完美性的耦合会减小SIF,而磁学-电学不完美性的耦合不会影响SIF;磁场作用下,增大压磁层弹性模量会减小SIF,而增大压电层压电系数,减小压电层弹性模量和介电常数,均会减小SIF;界面不完美性会影响SIF随裂纹倾斜角度或裂纹与界面之间距离的变化规律;在一定范围内增加压电层或压磁层厚度可以减小SIF。     

非理想界面正交各向异性层/压电半空间结构中Love波的传播特性

研究了正交各向异性层与压电半空间非理想连接时Love波的传播特性。其中,界面条件由剪切滞后模型表征,正交各向异性层表面机械自由。首先,对压电材料和正交各向异性材料的波动方程进行求解,然后利用界面条件和边界条件推导了显函形式的频散方程,最后进行了数值计算,分析了界面性态、压电材料性能和正交各向异性程度对频散特性的影响。分析结果表明：Love波的传播速度随着界面约束强度的降低而减小;当不理想程度较高时,正交各向异性程度和压电材料性能对Love波的传播速度影响不大。     

界面改性对钛酸铅／环氧树脂压电复合材料性能的影响

采用ＫＨ－５５０对钛酸铅粉末进行表面处理。通过对ＰＴ／环氧树脂和处理ＰＴ／环氧树旨两种压电复合材料的压电应变常数,耐热性和耐冲击强度的测定和对比,研究了界面改性对压电复合材料的压电性能的影响。结果表明：通过界面改性,可以明显提高复合材料的耐热性和耐击穿强度,耐对饱和极化时的压电应变常数无影响。     

非理想界面功能梯度压电/压磁层状半空间结构中的SH波

研究非理想界面下功能梯度压电/压磁层状半空间结构中SH波的传播特性。界面性能由“弹簧”模型表征, 假设功能梯度压电层材料性能沿层厚度方向指数变化, 其表面为电学开路。推导了频散方程, 并结合数值算例分析了界面性能、功能梯度压电层的梯度变化和厚度对相速度的影响。研究结果对功能梯度压电/压磁复合材料在声波器件中的应用提供了理论依据。     

压电压磁双层材料界面二维裂纹分析

该文利用积分变换和奇异积分方程技术研究压电压磁双材料界面裂纹二维断裂问题.假设界面上压电材料电势和压磁材料磁势为零:压电层表面受机械载荷和电位移作用,压磁层表面受机械载荷和磁导作用.导出了相应问题的应力强度因子和机械能量释放率的表达式,给出了机械能量释放率的数值结果.结果表明:在同样机械载荷作用下,压电压磁双材料界面裂...     

压电螺型位错与椭圆夹杂界面导电刚性线的干涉效应

研究了无限大压电基体材料中压电螺型位错与含界面导电刚性线椭圆夹杂的电弹耦合干涉问题。运用求解复杂多连通域问题的复变函数方法,获得了椭圆夹杂和基体区域复势函数以及电弹性场的精确级数形式解答。利用广义Peach-Koehler公式导出作用于压电螺型位错上的位错力公式。主要讨论了刚性线几何尺寸和椭圆曲率对位错力的影响规律。分析结果表明:界面刚性线排斥基体中的位错,对靠近椭圆夹杂界面的螺型位错的运动和平衡位置有重要的影响。当刚性线的长度达到临界值,界面刚性线的存在会改变螺型位错与压电椭圆夹杂的干涉规律。椭圆夹杂的压缩系数变大,刚性线尺寸对位错力的影响也越大。     

用裂纹单元分析双压电材料界面力电耦合奇异场

为了求解双压电材料在机械荷载和(或)外加电场的作用下,界面裂纹尖端的力电耦合奇异场,提出了一种全数值方法。该全数值方法的实施可以分为两个部分:首先,用一维有限元方法求解不同压电材料界面裂纹尖端力电耦合奇异场特征解;然后,采用杂交有限元列式构造一种所谓的裂纹单元,在该杂交有限元的列式中,假设应力场和电位移场是利用上述一维有限元方法计算得到的特征解推导出来的;利用该单元可以得到全部的力电耦合奇异场的解。通过对单一压电材料中心裂纹尖端力电耦合奇异场的计算,该方法的准确性和高效性得到了验证;进而用该方法研究了双压电材料界面力电耦合场奇异场。     

Electro-elastic interaction between a moving screw dislocation and collinear interfacial rigid lines

This paper attempts to investigate the problem for the electro-elastic interaction between a piezoelectric moving dislocation and interfacial collinear rigid lines under combined longitudinal shear and in-plane electric field. Using Riemann–Schwarz's symmetry principle integrated with the analysis singularity of complex functions, we present the general elastic solution of this problem and the closed form solution for interface containing single rigid line. The expressions of electro-elastic fields and image force acting on moving dislocation are derived explicitly. The results show that the velocity of moving dislocation has significant effect on the image force. The present solutions contain previously known results as the special cases.     

Electro-elastic stress analysis for a screw dislocation interacting with a coated inclusion in piezoelectric solid

Summary. The electro-elastic stress investigation on the interaction problem of a piezoelectric screw dislocation near a coated inclusion in a piezoelectric material has been carried out. In our study, three dissimilar material phases are involved: the matrix, the inclusion and the coating layer. All the three materials are piezoelectric and with different material constants. Explicit closed-form analytical solutions for the stress and electric displacement fields are obtained by using the complex variable method. The image force acting on the screw dislocation is calculated by using the generalized Peach-Koehler formula. Numerical examples for different material constant combinations are performed. The influences of material properties of the inclusion and the coating layer on the image forces are examined and discussed.     

A piezoelectric screw dislocation in a three-phase composite cylinder model with an imperfect interface

The electroelastic coupling interaction between a piezoelectric screw dislocation and the embedded circular cross-section inclusions with imperfect interfaces in piezoelectric solids is investigated by using a three-phase composite cylinder model. By means of a complex variable technique, the explicit solutions of electroelastic fields are obtained. With the aid of the Peach-Koehler formula, the explicit expression for the image force exerted on the piezoelectric screw dislocation is derived. The image force on the dislocation and its equilibrium positions near one of the inclusions are discussed for variable parameters (interface imperfection and material electroelastic dissimilarity) and the influence of nearby inclusions is also considered. The results show that when compared with the previous solution (the perfect interface), more equilibrium positions of the screw dislocation in the matrix may be available due to the effect of the interface imperfection when the dislocation is close to the electroelastic stiff inclusion. It is also found that the magnitude of the image force exerted on the piezoelectric screw dislocation produced by multiply inclusions is always smaller than that produced by a single inclusion and the impact of nearby inclusions on the mobility of the screw dislocation is very important.     

Piezoelectric study for a coated hole of quasi-polygonal shape in an infinite plate

This paper studies the piezoelectric problems for a coated hole of quasi-polygonal shape embedded in an infinite matrix subjected to electromechanical loadings. The electromechanical loadings considered in this work include a screw dislocation, a point force, a point charge, a far-field anti-plane shear and an in-plane electric field. Each component is assumed to be transversely isotropic medium belonging to a hexagonal crystal class 6 mm and poled in the x₃ direction. Based on the complex variable and analytical continuation method, the general expressions for the complex potentials can be derived in each medium. Numerical results are provided to show the effect of hole shape, the material combinations and the loading condition on the electro-elastic fields due to the presence of the coated film. The image force exerted on a dislocation, which can be used to probe the mobility of the screw dislocation, will be calculated by means of the generalized Peach-Koehler formula.     

Electro-elastic stress analysis for a wedge-shaped crack interacting with a screw dislocation in piezoelectric solid

The electro-elastic stress investigation on the interaction problem of a screw dislocation near the tip of a semi-infinite wedge-shaped crack in piezoelectric material has been carried out. Explicit closed-form analytical solutions are obtained for the stress intensity factor (SIF) and the electric displacement intensity factor (EDIF) of the crack, as well as the force on dislocation. The derivation is based on the conformal mapping method and the perturbation technique. The dislocation has Burger's vector normal to the isotropic basal plane, with a line force and a line charge being applied at the core of the dislocation. The influence of the location and the wedge angle of the crack on the image force of the dislocation has been discussed in detail. At the same time the effect of the dislocation on the crack behavior has been also examined under different configurations. Two types of PZT materials are used to numerically illustrate the influences of the wedge angle and the location of the dislocation on the image force and the crack intensities. Results obtained in the current study can be fully reduced to various special cases available in the literatures.     

Screw dislocation interacting with interfacial and interface cracks in piezoelectric bimaterials

Interface and interfacial cracks interacting with screw dislocations in piezoelectric bimaterials subjected to antiplane mechanical and in-plane electrical loadings are studied within the framework of linear piezoelectricity theory. Straight dislocations with the Burgers vector normal to the isotropic basal plane near the interface or interfacial crack are considered. The dislocations are characterized by a discontinuous electric potential across the slip plane and are subjected to a line-force and a line-charge at the core. An explicit solution for the screw dislocation in piezoelectric bimaterial with straight interface is found based on the solution of a similar problem for infinite homogenous medium. The obtained relation is independent of the nature of singularity. This fundamental result is used to analyze dislocation interacting with a set of collinear interfacial cracks in piezoelectric bimaterials. Three solutions for the screw dislocation interacting with a semi-infinite crack, finite crack, and edge crack between two bonded dissimilar piezoelectric materials are obtained in closed-form. These solutions can be used as Green’s functions for the analyses of interfacial cracks in piezoelectric bimaterials.     

压电材料中螺型位错与含界面刚性线圆形涂层夹杂的干涉

研究了压电材料中位于基体的螺型位错与含界面刚性线圆形涂层夹杂的电弹耦合干涉问题。运用复变函数方法,获得了基体、涂层和夹杂中复势函数的精确级数形式解答。基于广义Peach-Koehler公式,计算了作用在位错上的像力。讨论了刚性线几何条件、界面层厚度和材料电弹特性对位错力和位错平衡位置的影响规律。结果表明:对于软夹杂和软涂层的情况,刚性线长度存在一个临界值改变像力的方向。螺型位错先被吸引后被排斥,在夹杂附近有一个稳定的平衡点。对于硬夹杂和硬涂层的情况,位错一直被排斥,刚性线对位错力的影响较小。     

The interaction between a screw dislocation and a nano-inhomogeneity with a semi-infinite wedge crack penetrating the interface

The interaction between a screw dislocation and a circular nano-inhomogeneity with a semi-infinite wedge crack penetrating the interface is investigated. By using Riemann-Schwartz’s symmetry principle integrated with the analysis of singularity of complex functions and the conformal mapping technique, the analytical expressions of the stress field in both the circular nano-inhomogeneity and the infinite matrix, the image force acting on the screw dislocation and the stress intensity factor at the crack tip are obtained. The influence of elastic mismatch of materials, inhomogeneity size, interface stress, wedge crack opening angle and the relative location of dislocation on the image force and on the equilibrium position of the screw dislocation and the shielding effect of the screw dislocation are discussed in detail. The results show that interface stress has a significant impact on the movement of dislocations near the interface, and the effect of interface stress enhances when the inhomogeneity radius decreases. With the decrease in the wedge crack opening angle, the influence of interface stress on the movement of the screw dislocation and on the SIF enhances. With the increment of the relative shear modulus, the influence of interface stress weakens with the screw dislocation locating in the inhomogeneity and strengthens with the screw dislocation locating in the matrix. When the screw dislocation is located in the inhomogeneity, the positive (negative) interface stress increases (decreases) the shielding effect, while this phenomenon is opposite when the screw dislocation locates in the matrix.