含中心裂纹正交各向异性板均匀热流作用下的温度场解析解

研究了含中心裂纹的正交各向异性板,在远场均匀热流作用下温度场的分布。考虑了两种温度边界条件,即裂纹表面分别维持恒定的温度与恒定的温度梯度,包括了绝热裂纹与导热裂纹等情况。采用各向异性热弹性理论与复变函数理论,得出了精确满足给定边界条件的温度场的全场解析解。算例中的温度场分布数值结果,出现了一些新的现象,值得进一步进行深入理论探讨与实验观测的证实。     

基于Ansys的0-3型压电振子的有限元分析

0-3型压电复合材料以其柔软性,易加工成型和制备工艺简单等优点,具有广泛的应用前景.该文利用0-3型压电复合材料作为压电悬臂梁压电振子的压电体,利用Ansys软件对振子做有限元分析,包括静态和模态分析,得出压电振子各参数对其发电能力及谐振频率的影响:振子发电能力与外力及振子的长度成正比,与振子宽度成反比,存在最佳长度比和厚度比;振子的固有频率与长度及质量块的质量成反比,宽度对固有频率的影响较小.这些数据为压电悬臂梁的结构参数提供设计依据.     

Applications of thermoelastic stress analysis to composite materials

A number of applied thermoelastic stress analysis (TSA) studies on composite components and assemblies are described, for the purpose of illustrating the potential of the technique for use with composite materials.     

现代军用桥梁的疲劳问题分析

随着现代军用桥梁的发展,尤其是大量屈服强度450 MPa以上的高强度钢材和冷弯焊接构件的使用以及一些新型结构型式和制造工艺的不断出现,现代军用桥梁构件的疲劳性能需要给予特别关注。在分析军用桥梁疲劳性能影响因素、疲劳荷载的基础上,探讨了现代军用桥梁中常用的一些典型构造细节的疲劳性能,并总结了防止军用桥梁疲劳破坏的方法,不仅可以有效地防止军用桥梁疲劳破坏事故的发生,而且对提高军用桥梁的设计和制造水平也具有非常重要的意义。     

Finite element-computation of the electromechanical J-Integral for 2-D and 3-D crack analysis

Piezoelectric ceramics find an application in many fields of technology. They may serve as sensors or actuators, mostly beeing exposed to high electric and mechanical loads. Therefore, fracture mechanics of piezoelectrics is an important field preserving strength and reliability under different conditions of application. This paper deals with the calculation of electromechanical energy release rates for arbitrary cracks in spatial piezoelectric structures applying a generalized J-integral. The crack problem is solved using a commercial FEM-code obtaining electric and mechanical field variables in nodes and integration points. These results serve as input data for the numerical computation of the electromechanical J-integral. The results are compared to findings from analytical and alternative numerical methods.     

金属拱型波纹屋顶材料等效拉伸弹性模量试验研究与分析

按照正交各向异性薄板理论对金属拱型波纹屋顶结构模型进行了合理的简化，以对原材料T型板、U型板进行的拉伸试验为基础．分析位移随荷载变化的曲线，得到了T型和U型两种截面型式板材腹板和底板的材料等效拉伸弹性模量．并与平板的拉伸弹性模量值进行了比较分析。     

A simple but exact method for vibration analysis of composite laminated plates with all edges simply supported and under lateral and in-plane loading

A simple but exact method of calculating the natural frequencies of vibration for some structural members with all edges simply supported and under lateral and in-plane loading, is presented herein. This method uses the deflection influence surfaces which can be obtained by any method for vibration analysis and consists of determining the deflected mode shape of the member due to the inertia force under resonance condition. Beginning with initially guessed mode shape, exact mode shape is obtained by the process similar to iteration. In this paper, equations are given for the case of special orthotropic laminates. However, the same equations can be used for any laminate as long as B₁₆, B₂₆, D₁₆, and D₂₆ are negligible as the number of plies increases and some laminates having such properties are presented.     

Bioinspired Interlocked and Hierarchical Design of ZnO Nanowire Arrays for Static and Dynamic Pressure‐Sensitive Electronic Skins

The development of electronic skin (e‐skin) is of great importance in human‐like robotics, healthcare, wearable electronics, and medical applications. In this paper, a bioinspired e‐skin design of hierarchical micro‐ and nano‐structured ZnO nanowire (NW) arrays in an interlocked geometry is suggested for the sensitive detection of both static and dynamic tactile stimuli through piezoresistive and piezoelectric transduction modes, respectively. The interlocked hierarchical structures enable a stress‐sensitive variation in the contact area between the interlocked ZnO NWs and also the efficient bending of ZnO NWs, which allow the sensitive detection of both static and dynamic tactile stimuli. The flexible e‐skin in a piezoresistive mode shows a high pressure sensitivity (?6.8 kPa^?1) and an ultrafast response time (<5 ms), which enables the detection of minute static pressure (0.6 Pa), vibration level (0.1 m s^?2), and sound pressure (≈57 dB). The flexible e‐skin in a piezoelectric mode is also demonstrated to be able to detect fast dynamic stimuli such as high frequency vibrations (≈250 Hz). The flexible e‐skins with both piezoresistive and piezoelectric sensing capabilities may find applications requiring both static and dynamic tactile perceptions such as robotic hands for dexterous manipulations and various healthcare monitoring devices.     

Stress singularity analysis for orthotropic V‐notches in the generalised plane strain state

The singularity for the V‐notch under the generalised plane deformation is investigated by the combination of the asymptotic analysis with the interpolating matrix method developed by part of the authors before. The displacement asymptotic expansions at the vicinity of the V‐notch vertex are introduced into the equilibrium equations, which are transformed into a set of characteristic ordinary differential equations with respect to the notch singularity orders. The boundary conditions and interfacial compatibility conditions are also represented by the combination of the singularity orders and characteristic angular functions. The determination of the singularity orders and characteristic angular functions are transformed into solving the ordinary differential equations with variable coefficients, which are solved by the interpolating matrix method. The present method is suitable for the singularity analysis for isotropic and orthotropic V‐notches. It is versatile for analysing the stress singularity of single material V‐notches, bi‐material V‐notches, interface edges and cracks. The correctness of the results by the proposed method is ensured by the comparison with the published ones.