光机械式红外探测器中镜面弯曲对探测灵敏度的影响

光学读出式红外成像技术是近年来研究的热点，本文讨论了镜面弯曲对光学检测灵敏度的影响。由双材料微悬臂梁组成的非致冷焦平面阵列通过体刻蚀工艺加工而成，由于残余应力的影响，制成的焦平面阵列将会发生弯曲，应力导致的镜面弯曲将会降低光学探测灵敏度。本文通过傅立叶光学模拟了镜面弯曲对光学探测灵敏度的影响，并通过实验验证了该模型。实验和模拟结果表明，在镜面曲率为0．1mm-1时，光学探测灵敏度将会降低到理想情况的40％。最后我们用这个模型评价了通过表面修饰来提高光学性能的效果。     

利用松质骨理想化模型对骨小梁刚度的研究

利用结构张量的概念建立了考虑松质骨结构各向异性的理想模型，将杆型与板型两种传统模型统一起来．采用均匀化理论，通过有限单元的数值计算建立了松质骨弹性常数与结构张量、固体体积比之间的数值关系，并预测了骨小梁的弹性模量．结果表明，本文模型较好地体现了松质骨的各向异性力学性质．对骨小梁的计算结果表明，骨小梁的弹性模量在６７６ＧＰａ～１０９ＧＰａ范围内，平均意义上的结果是９２１ＧＰａ．     

A tensorial description of the transformation kinetics of the martensitic phase transformation

Based on a local examination of the phase transition front, a macroscopic second order tensor describing the thermodynamic force for the phase transformation is proposed. Consequently, an associated thermodynamic flux is introduced. These tensorial variables are embedded into a material law which describes the behavior of steels during the austenite–martensite phase transformation. The material law is implemented into a finite element formulation. Homogeneous tests in pure tension/compression and torsion are performed to verify the behavior of the material law. Due to the independent modeling of the behavior of the phases, the influence of the yield stress of the austenite on the transformation kinetics can be verified. A classical example is presented to show the ability of the model to calculate large structural problems.     

Phase equilibrium in non-fluids and non-fluid mixtures

A criterion of phase equilibrium for mixtures of materials with arbitrary symmetry (e.g. between solid and fluid or two solid mixture phases) is deduced using a rational thermodynamics approach. This criterion, known also as Maxwell relation, is expressed via the difference of chemical potential tensors (Eshelby tensors) on the singular surface dividing the bulk phases.The thermomechanical balance equations, the entropy inequality and the Maxwell relation for phase equilibrium are given first for the case of pure (one-constituent) materials of arbitrary symmetry and then for the case of mixtures (including chemically reacting ones) of arbitrary symmetry.In the special case of fluids it is shown that the chemical potential tensors reduce to the classical scalar chemical potentials and the Maxwell relations to the classical thermodynamic criterion for the phase equilibrium.     

A Concise Proof of the Representation Theorem for Fourth-Order Isotropic Tensors

We present a new proof of the representation theorem for fourth-order isotropic tensors that does not assume the tensor to have major or minor symmetries at the outset.     

A micromechanical analysis of damage propagation in fluid-saturated cracked mediaUne analyse micromécanique de la propagation de l'endommagement d'une fissure sous pression de fluide

We first revisit the well known framework of Linear Elastic Fracture Mechanics (LEFM) in the case of a fluid-saturated crack. We next consider a r.e.v. of cracked medium comprising a family of cracks characterized by the corresponding crack density parameter ε. Generalizing the classical energy approach of LEFM, the proposed damage criterion is written on the thermodynamic force associated with ε, which is estimated by means of standard homogenization schemes. This criterion proves to involve a macroscopic effective strain tensor, or alternatively the Terzaghi effective stress tensor. The stability of damage propagation is discussed for various homogenization schemes. A comparison with experimental results is presented in the case of a uniaxial tensile test on concrete. To cite this article: L. Dormieux et al., C. R. Mecanique 334 (2006).     

非比例循环塑性内时本构关系研究

在Valanis的内时本构理论的框架中,引入内结构张量以反映由于非比例加载而引起金属材料的附加等向强化及异向强化效应,同时提出材料强化程度的度量采用沿路径法线方向的塑性应变分量来描述.这些考虑的有效性已经通过用所建模型对304不锈钢材料在一些典型非比例循环加载路径下的响应进行的理论预测得到了验证;将该模型应用于U71Mn材料室温单轴棘轮行为描述中,结果显示内结构张量的引入不仅能较好地反映应变控制下的非比例附加效应,而且也能较好地反映应力控制下塑性应变的累积及变化率.