形状记忆执行材料的研究进展

形状记忆材料是一种重要的智能材料,主要作为执行器件材料,被广泛的用在建筑、航空航天、军事和医学等领域.近年来形状记忆材料的研究和应用受到研究人员的重视.本文综述了近几年形状记忆合金、形状记忆陶瓷和形状记忆聚合物的新的研究成果和研究方向,展望了形状记忆材料未来的发展趋势.     

形状记忆执行材料研究进展

形状记忆材料是一种重要的智能材料，主要作为执行器件材料，被广泛的用在建筑、航空航天、军事和医学等领域。近年来形状记忆材料的研究和应用受到研究人员的重视。本文综述了近几年形状记忆合金、形状记忆陶瓷和形状记忆聚合物的新的研究成果和研究方向，展望了形状记忆材料未来的发展趋势。     

智能材料和智能结构——形状记忆材料

研究了形状记忆材料,如形状记忆合金、陶瓷和聚合物的结构、生产方法、特性和应用。形状记忆材料具有许多优秀的智能特性,例如传感（热、应力和场）、大行程执行器、高阻尼、自适应响应、形状记忆、超弹性等,可用于各种智能系统。形状记忆材料中的激励感应相变导致了材料的许多独特的性能,支配着材料性质的显著变化。讨论了改进目前材料系统和研发新的形状记忆材料所面临的技术障碍和挑战。     

智能材料和智能结构(2)——混合复合材料

将智能记忆材料与其它功能材料或结构材料相混合可生产出智能复合材料,可由复合材料的各组成材料的独特性质调谐复合材料的性质以自适应环境的变化。本文从材料学的观点研究了各种混合复合材料的设计、制造、特性和应用,包括：纤维增强、颗粒增强和多层薄膜形状记忆复合材料。     

具有形状记忆功能的照明灯

法国《科学与生活》月刊1995年3月号报道:巴黎建筑学院的奥利维埃·肖邦设计了一种城市照明灯。 这种灯有两瓣随着灯亮而逐渐张开或随着灯灭而逐渐合上的叶片。 这种照明灯是用具有形状记忆功能的合金材料制造的。这种材料根据它受到的热度突然或逐渐改变形状和恢复原来的形状。     

基于协议的实时构件行为一致性验证

对复杂实时构件系统行为进行形式化描述和一致性验证,可以提高实时构件的可复用性和系统的正确性、可靠性。分析了时间行为协议TBP(Timed Behavior Protocol)及其它学术界和工业界常用的时序行为形式化描述方法,对实时构件替换理论进行了讨论,给出了基于时间行为协议的构件一致性验证算法并对其进行了分析。     

TCBV:一种构件时序行为建模与相容性验证工具

利用形式化方法对复杂实时构件系统的时序行为进行建模与验证对于提高安全攸关实时构件系统的正确性、可靠性与安全性具有重要意义。介绍了基于时间行为协议的构件时序行为的形式化建模和相容性验证方法,给出了时间行为协议建模与相容性验证工具TCBV的系统架构与功能模块。TCBV应用方便,能够实现实时构件时序行为模型的图形化表示,并可对复杂交互行为的相容性进行自动验证。结合应用实例,介绍了如何利用TCBV对复杂实时构件系统的时序行为进行建模和验证。最后,将TCBV与其它相关工具进行了比较。     

构件行为协议实时性扩展及相容性验证

对复杂实时构件系统行为进行形式化描述和相容性验证,可以有效提高系统的正确性、可靠性。分析了学术界和工业界的主流构件模型及常见时间行为的形式化描述方法,对构件行为协议BP(Behavior Protocol)进行了扩展,提出了时间行为协议TbP(Timed Behavior Protocol),分析了构件组合中常见的相容性错误类型,给出了基于时间行为协议的构件组合相容性验证算法。TBP应用简洁、方便、易于验证。结合具体例子给出了应用示例。     

大载荷形状记忆合金热敏元件的开发

<正> 一、概述 形状记忆合金已有40多年的发展历史,世界各国一直抱有浓厚的兴趣开展记忆合金的机理研究和应用开发。 形状记忆合金具有所谓伪弹性、热弹性及形状记忆效应。其中,形状记忆效应的应用最广泛,也最有市场。形状记忆效应是记忆合金材料由母相冷却成马氏体,在马氏体状态下进行变形后,当材料升高     

基于范畴论的构件行为组合研究

针对基于构件开发过程中单个构件功能难于满足用户需求的问题,提出一种利用范畴论对构件行为进行组合的方法,用以实现复杂的业务功能。采用范畴论给出构件的形式语义描述,构件与构件之间的行为交互关系采用图表进行建模。给出一种基于图表推出的构件行为组合方法与推出运算的算法实现。实际应用结果表明,该方法对构件的形式化描述更加精确,构件组合也更加有效快捷。     

基于PCL的一维形状记忆合金系统的开发与应用

智能材料的发展给结构设计带来新的方向,同时也给商用有限元软件的应用迎来新的挑战.由于MSC Nastran的局限性,尚不能很好地模拟一些智能材料.结合实际工程需要,利用Patran完善的前、后处理功能及二次开发语言,将一维形状记忆合金(Shape Memory Alloys,SMA)材料系统集成到Patran中,能方便地实现在Patran中定义其材料属性和对布置有SMA的驱动结构以及复合材料结构的快速建模分析,最后利用本文系统建立SMA复合梁以及SMA丝驱动的机翼后缘模型,并进行验证,证明此模块功能的正确性和有效性.     

Sensitivity analysis of shape memory alloy shells

This paper presents procedures for efficient design sensitivity analysis for shape memory alloy (SMA) structures modeled with shell elements. Availability of sensitivity information at low computational cost can dramatically improve the efficiency of the optimization process, as it enables use of efficient gradient-based optimization algorithms. The formulation and computation of design sensitivities of SMA shell structures using the direct differentiation method is considered, in a steady state electro-thermo-mechanical finite element context. Finite difference, semi-analytical and refined semi-analytical sensitivity analysis approaches are considered and compared in terms of efficiency, accuracy and implementation effort, based on a representative finite element model of a miniature SMA gripper.     

Ferromagnetic shape memory flapper

A new method for propulsion using a Ni₂MnGa ferromagnetic shape memory flapper is introduced. We optically examine the magnetic field induced strain of pure shear by means of a state of the art generator that provides alternating magnetic fields of 7000 Oe at frequencies of up to 100 Hz. Preliminary measurements show local shear deformation of about 5%, which open new frontiers in propulsion mechanisms.     

Generation of shape functions for straight beam elements

Straight beam finite elements with greater than two nodes are used for edge stiffening in plane stress analyses and elsewhere. It is often necessary to match the number of nodes on the edge stiffener to the number on a whole plane stress element side. Beam elements employ shape functions which are recognised to be level one Hermitian polynomials. An alternative to the commonly adopted method for determining these shape functions is given in this note, using a formula widely reported in mathematical texts which has hitherto not been applied to this task in the finite element literature. The procedure derives shape functions for beams entirely from the set of Lagrangian interpolating polynomials. Examples are given for the derivation of functions for a three and four-noded beam element.     

Modeling of shape memory alloy shells for design optimization

A three-dimensional phenomenological constitutive model for the analysis and design optimization of shape memory alloy (SMA) structures is presented. This model specifically targets the pseudoelastic behavior due to the R-phase transformation in NiTi alloys, but also applies to similar SMA materials with low hysteresis. A history-independent formulation is presented, which allows cost-effective sensitivity analysis. The possibility to efficiently compute design sensitivities is essential for enabling the use of gradient-based optimization algorithms, which will allow design optimization of complex SMA structures. The use of the constitutive model in a problem of realistic complexity is illustrated by the analysis of a SMA miniature gripper, modeled using shell elements. The sensitivity analysis of SMA structures using the presented model is addressed in an accompanying paper.     

Adaptive FE-procedures in shape optimization

In structural optimization the quality of the optimization result strongly depends on the reliability of the underlying structural analysis. This comprises the quality and range of the mechanical model, e.g. linear elastic or geometrically and materially nonlinear, as well as the accuracy of the numerical model, e.g. the discretization error of the FE-model. The latter aspect is addressed in the present contribution. In order to guarantee the quality of the numerical results the discretization error of the finite element solution is controlled and the finite element discretization is adaptively refined during the optimization process. Conventionally, so-called global error estimates are applied in structural optimization which estimate the error of the total strain energy. In the present paper local error estimates are introduced in shape optimization which allow to control directly the discretization error of local optimization criteria. In general, the adaptive refinement of the finite element discretization by remeshing affects the convergence of the optimization process if a gradient-based optimization algorithm is applied. In order to reduce this effect the sensitivity of the discretization error must also be restricted. Suitable refinement indicators are developed for globally and locally adaptive procedures. Finally, the potential of two techniques, which may improve the numerical efficiency of adaptive FE-procedures within the optimization process, is studied. The proposed methods and procedures are verified by 2-D shape optimization examples. Received June 3, 1999     

形状记忆合金丝编织网气动肌肉机构及其阻抗控制

气动肌肉是仿生机器人研究的重点,为此,设计了形状记忆合金丝编织网气动肌肉机构.通过等效气缸和等效动力学分析,建立了输出力模型,设计了含位置PID内环的阻抗控制,并建立了阻抗模型,通过拉氏变换和频域分析给出了稳定条件.理论分析表明,合金丝的收缩可增大气动肌肉的输出力和调节刚度.在Matlab上开展阻抗参数对柔顺性影响的仿真实验,结果表明刚度对于接触力影响最大,阻抗控制可实现接触力和位置的协调控制.     

Magnetic flux memory effect using a magnetostrictive material-shape memory piezoelectric actuator composite

A magnetostrictive-shape memory piezoelectric material composite is proposed to realize a magnet field memory effect. An imprint electrical field enables a shape memory piezoelectric actuator, and the shape memory effect maintains a certain permeability of the magnetostrictive materials. A new magnetic flux memory effect is generated using a composite of the magnetostrictive-shape memory piezoelectric actuator and a permanent magnet. This magnetic flux memory effect can be operated with a pulsed voltage to the shape memory piezoelectric actuator, so that no energy is consumed to maintain a certain magnetic effect.     

Modeling of pneumatic muscle with shape memory alloy and braided sleeve

Pneumatic muscle (PM) of flexible actuators used in bionic robot is an active area of recent research. A novel PM with shape memory alloy (SMA) braided sleeve is proposed in this paper, and SMA is used to improve PM working characteristics. Based on the principle of virtual work, output force model of PM and relationship with braided wire inner-stress are established, and analysis of PM deformation has shown that braided wire length is the key factor of output force characteristic. Based on the crystal structure transitions, the relationship of temperature with wire shrinkage is derived. Then, the synthetic dynamics of novel PM is established. A physical prototype of PM with SMA braided sleeve is developed, and test platform that is built for the experiment. Experiment and simulation test of static isometric-length, static isobaric-pressure, and dynamic characteristics are done. The experimental results are compared with the simulation of theoretical model. Moreover, based on experiment, model of output force was improved by adding a correction factor to deal with the elastic force of rubber tube. The results analysis demonstrates that the established models are correct, and SMA wires can reinforce PM and make PM working characteristics adjustable. PM proposed in this paper has greater output force and is beneficial to achieve more accurate control that is useful for manipulating fragile things.     

Finite element-based multi-phase modelling of shape memory polymer stents

In the western hemisphere almost the half of all events of death are caused by cardiovascular diseases, e.g. strokes and heart attacks. The latter are consequences of arteriosclerosis leading to abnormal deposits (plaque) in blood vessels. In order to avoid the serious symptoms discussed in the above or to hold affected blood vessels open, tubular structures made of metallic or polymeric materials (stents) are implanted.In the paper we discuss the modelling of a new kind of stents, so-called shape memory polymer (SMP) stents. The first part of the paper is devoted to the thermo-mechanical modelling of these materials. Aspects as the transition from entropy to energy elasticity are included. The constitutive equations are derived in the framework of large strains. We follow both, a purely macroscopic as well as a micromechanically motivated approach. In the second part of the work representative examples based on realistic stent structures are used to validate the model.