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991.
992.
Imperfect bonding between the constitutive components can greatly affect the properties of the composite structures.An asymptotic analysis of different types of imperfect interfaces arising in the problem of 2D fibrereinforced composite materials are proposed.The performed study is based on the asymptotic reduction of the governing biharmonic problem into two harmonic problems.All solutions are obtained in a closed analytical form.The obtained results can be used for the calculation of pull-out and pushout tests,as well as for the investigation of the fracture of composite materials. 相似文献
993.
994.
We present a fully general, three dimensional, constitutive model for Shape Memory Alloys (SMAs), aimed at describing all of the salient features of SMA evolutionary response under complex thermomechanical loading conditions. In this, we utilize the mathematical formulation we have constructed, along with a single set of the model’s material parameters, to demonstrate the capturing of numerous responses that are experimentally observed in the available SMA literature. This includes uniaxial, multi-axial, proportional, non-proportional, monotonic, cyclic, as well as other complex thermomechanical loading conditions, in conjunction with a wide range of temperature variations. The success of the presented model is mainly attributed to the following two main factors. First, we use multiple inelastic mechanisms to organize the exchange between the energy stored and energy dissipated during the deformation history. Second, we adhere strictly to the well established mathematical and thermodynamical requirements of convexity, associativity, normality, etc. in formulating the evolution equations governing the model behavior, written in terms of the generalized internal stress/strain tensorial variables associated with the individual inelastic mechanisms. This has led to two important advantages: (a) it directly enabled us to obtain the limiting/critical transformation surfaces in the spaces of both stress and strain, as importantly required in capturing SMA behavior; (b) as a byproduct, this also led, naturally, to the exhibition of the apparent deviation from normality, when the transformation strain rate vectors are plotted together with the surfaces in the space of external/global stresses, that has been demonstrated in some recent multi-axial, non-proportional experiments. 相似文献
995.
Daniel PaquetPiyush Dondeti Somnath Ghosh 《International Journal of Plasticity》2011,27(10):1677-1701
This paper proposes a nested dual-stage homogenization method for developing microstructure based continuum elasto-viscoplastic models for large secondary dendrite arm spacing or SDAS cast aluminum alloys. Microstructures of these alloys are characterized by extremely inhomogeneous distribution of inclusions along the dendrite cell boundaries. Traditional single-step homogenization methods are not suitable for this type of microstructure due to the size of the representative volume element (RVE) and the associated computations required for micromechanical analyses. To circumvent this limitation, two distinct RVE’s or statistically equivalent RVE’s are identified, corresponding to the inherent scales of inhomogeneity in the microstructure. The homogenization is performed in multiple stages for each of the RVE’s identified. The macroscopic behavior is described by a rate-dependent, anisotropic homogenization based continuum plasticity (HCP) model. Anisotropy and viscoplastic parameters in the HCP model are calibrated from homogenization of micro-variables for the different RVE’s. These parameters are dependent on microstructural features such as morphology and distribution of different phases. The uniqueness of the nested two-stage homogenization is that it enables evaluation of the overall homogenized model parameters of the cast alloy from limited experimental data, but also material parameters of constituents like inter-dendritic phase and pure aluminum matrix. The capabilities of the HCP model are demonstrated for a cast aluminum alloy AS7GU having a SDAS of 30 μm. 相似文献
996.
997.
Analysis of energy consumption in microwave and convective drying process of multi-layered porous material inside a rectangular wave guide 总被引:1,自引:0,他引:1
W. JindaratP. Rattanadecho S. Vongpradubchai 《Experimental Thermal and Fluid Science》2011,35(4):728-737
This work applies the first law of thermodynamics to estimate the ratio of energy utilization in microwave drying process using a rectangular waveguide. Two porous packed bed systems are considered such as attaching fine bed on coarse bed (F-C) and attaching coarse bed on fine bed (C-F). The effects of layered configuration and layered thickness on drying rate, power absorbed efficiency, specific energy consumption (SEC), and energy efficiency are studied in detail. The results show that the variations of all parameters have strongly affected on microwave penetration depth and power absorbed within the packed bed. Furthermore, F-C bed with equal layer thickness corresponds to great energy efficiency. 相似文献
998.
软材料受刺激会发生变形, 该变形会引起相应的功能, 这种材料称为活性软材料(soft active material, SAM). 本综述主要讨论介电高弹聚合物这一类活性软材料. 当介电高弹聚合物薄膜受到厚度方向的电压作用时, 薄膜厚度减小同时面积增大, 可导致超过100{\%}的应变. 介电高弹聚合物作为转换器被广泛应用, 包括柔性机器人、智能光学器件、盲文显示屏、发电机等. 本文综述了建立在连续介质力学和热力学框架内的、并且基于分子理论描述和经验观测的介电高弹聚合物理论. 该理论耦合了大变形和电势, 描述了非线性和非平衡行为, 如力电失稳和黏弹性. 采用该理论能够通过有限元方法模拟实际构型的转换器, 计算力电能量转换的效率, 给出电致大变形的可行途径. 该理论有助于材料和器件设计. 相似文献
999.
1000.