形状记忆合金螺旋弹簧的设计

从形状记忆合金应力、应变、温度的数学模型出发,考虑到形状记忆效应最佳时的临界变形量,提出了形状记忆合金螺旋弹簧及形状记忆合金驱动器的设计方法和步骤。针对形状记忆合金螺旋弹簧设计的复杂性和几何参数的不确定性,介绍了以Ｄ／ｄ３＝πτ／８ＫＰ为约束条件的满应力优化设计法。     

形状记忆合金螺旋弹簧的设计

从形状记忆合金应力、应变、温度的数学模型出发,考虑到形状记忆效应最佳时的临界变形量,提出了形状记忆合金螺旋弹簧及形状记忆合金驱动器的设计方法和步骤。针对形状记忆合金螺旋弹簧设计的复杂性和几何参数的不确定性,介绍了以Ｄ／ｄ＾３＝πτ／８ＫＰ为约束条件的满应力优化设计法。     

形状记忆合金双程弯曲驱动器的设计及试验

为解决变体机翼中蒙皮大变形与承载力之间的矛盾,同时满足光顺性及疲劳寿命的要求,提出了一种以形状记忆合金板为驱动元件的双程弯曲驱动器。基于形状记忆效应及材料力学弯曲理论,通过对驱动器变形过程中的力学特性进行分析,推导出双程弯曲驱动器的设计理论,再利用热成形法与反变形训练法制备出驱动器样件并进行了变形性能测试。研究结果表明：依据推导出的理论所设计的形状记忆合金双程弯曲驱动器的变形量与试验结果一致;随着加热温度的升高,驱动器的挠度及输出力逐渐增大,直至达到最大值;随着回复弹簧钢板厚度的增大,驱动器的最大挠度及最大输出力减小,加热变形响应速度减慢,但冷却回复响应速度加快;经过循环激励后,驱动器的变形效果稳定。     

用于柔性机械手的形状记忆合金驱动器滑模控制研究

提出了一种新型结构形式的形状记忆合金驱动器——内嵌式形状记忆合金驱动器。该驱动器将U形回复形状记忆合金丝嵌入弹性硅胶棒内，通过温控方式实现驱动器的往复可逆弯曲运动，对外稳定输出力和位移。研究了驱动器运行机理，探讨了基于形状记忆合金电阻反馈的变结构滑模控制策略，进行了仿真和实验研究。     

形状记忆合金线性驱动器的设计及位移特性分析

为克服传统带有偏置装置形状记忆合金驱动器结构复杂、响应速度慢的缺点,利用形状记忆合金(Shape memory alloy,SMA)的单程形状记忆效应,设计并制造一种不带偏置装置且可实现双程运动的线性驱动器,该驱动器由两根形状记忆合金丝、滑轮、部件、导轨、支座及固定螺钉组成。接着基于Brinson一维本构方程及转换方程,推导出两根SMA丝在不同条件下的应变表达式;提出将马氏体相变应力看作体力,分析温度变化与驱动器位移的关系及外载荷变化对驱动器最大位移的影响。对计算结果进行试验验证,结果表明,所设计驱动器可实现往复双程运动;随着SMA丝温度的升高所获得的位移呈非线性增大,当温度超过奥氏体转变结束温度Af,位移达到最大,而初始化过程获得的最大位移为正常运动的一半;增大载荷,驱动器的最大位移逐渐减小,当载荷达到51.0 N时,驱动器停止运动,即位移减小为零。     

基于形状记忆合金的热水发电装置设计

根据形状记忆合金(Shape Memory Alloys,简称SMA)的形状记忆效应设计制作了记忆合金作为动力器件并与单片机控制系统相结合的热水发电装置,该装置由Ni-Ti记忆合金丝转动驱动器部分、探温调整机构部分,发电机部分等构成。利用记忆合金的形状记忆效应引起的尺寸变化产生的力来驱动转子在绕线线圈中转动,使热能转变为机械能后驱动发电机发电,实现工业余热转化为电能。     

一种形状记忆合金扭转驱动器的制备与测试

研究了一种以镍钛（NiTi）形状记忆合金带材为基本驱动材料的平面涡卷式扭转驱动器。该驱动器利用NiTi合金的单程形状记忆效应与回复弹簧的相互作用,实现驱动器在高低温状态下正反两向的扭矩输出。分析了驱动器的基本结构形式和驱动原理,探讨了NiTi合金驱动部件的设计方法和基本制备工艺。设计制作了驱动器原理样机,并测试了驱动器的输入输出特性。测试结果表明,该驱动器在给定的高低温环境(10~60℃）下能够在正反两个方向连续稳定地输出扭矩,最大行程范围为0~175°,最大输出扭矩达到0.33N·m。实测结果证明了驱动器设计方案与制备工艺的可行性。     

基于三缸曲柄滑块机构的SMA驱动器设计

以实例为模型分析了基于形状记忆合金驱动器的原理,以及各主要功能环节的实现方式。研究探讨了旋转驱动器的实现可能,并设计了基于三缸曲柄滑块机构的形状记忆合金旋转驱动器,拓宽了基于形状记忆合金驱动器的发展潜力和应用前景。     

形状记忆合金智能结构的研究进展

形状记忆合金(SMA)以其形状记忆效应、伪弹性和高阻尼系数在工业界和医学领域得到了广泛的应用.本文分析了SMA材料的特性,综述了SMA器件及其在智能结构领域中的应用概况,分析了SMA驱动器存在的问题.     

形状记忆合金热机驱动器的研制

选用一定规格的形状记忆合金弹簧和普通弹簧来设计一台形状记忆合金热机驱动器,并以形状记忆合金弹簧作为驱动力。该形状记忆合金热机驱动器由热循环系统、动滑轮机构、齿形皮带传动机构三部分组成,具有机械结构简单、输出位移大等优点。     

Deformation by moving interfaces from single crystal experiments to the modeling of industrial SMA

Microstructure-based micromechanics models have to be developed in order to successively predict complex thermomechanical behaviors of shape-memory alloys (SMA). However, a proper implementation of the deformation mechanism—motion of internal interfaces in solid state—into the micromechanics models of SMA polycrystals is very important. In this work, experimental characteristics of the deformation mechanism surveyed from literature data obtained from uniaxial loadings of SMA single crystals are summarized. Original results of thermomechanical tension/compression loading experiments on CuAlNi and CuAlZnMn single crystals and CuAlZnMn polycrystals are also reported. Oriented single crystals may transform into different martensitic phases under various orientations of the uniaxial loading axes and sense of the applied stress. This phenomenon is called martensite formation anisotropy and possible consequences for thermomechanical behaviors of CuAlZnMn polycrystals are suggested.     

Empirical modeling of dynamic behaviors of pneumatic artificial muscle actuators

Pneumatic Artificial Muscle (PAM) actuators yield muscle-like mechanical actuation with high force to weight ratio, soft and flexible structure, and adaptable compliance for rehabilitation and prosthetic appliances to the disabled as well as humanoid robots or machines. The present study is to develop empirical models of the PAM actuators, that is, a PAM coupled with pneumatic control valves, in order to describe their dynamic behaviors for practical control design and usage. Empirical modeling is an efficient approach to computer-based modeling with observations of real behaviors. Different characteristics of dynamic behaviors of each PAM actuator are due not only to the structures of the PAM actuators themselves, but also to the variations of their material properties in manufacturing processes. To overcome the difficulties, the proposed empirical models are experimentally derived from real physical behaviors of the PAM actuators, which are being implemented. In case studies, the simulated results with good agreement to experimental results, show that the proposed methodology can be applied to describe the dynamic behaviors of the real PAM actuators.     

形状记忆合金在驱动器上的应用研究

随着新技术的快速发展,形状记忆合金作为一种重要的智能材料在制造、医疗和航空航天等领域有着越来越广泛的应用。形状记忆合金易于实现驱动器微型化和自动化,有着传统驱动器不可比拟的性能优点。本文总结基于智能材料的驱动器,探讨NiTi形状记忆合金驱动器的制造和驱动触发等问题以及新的研究方向。     

Calculation of mechanical behaviors of shape memory alloy under multi-axial loading conditions

In this paper, for the calculation of the deformation behaviors of shape-memory alloy under multi-axial loading conditions with temperature changes, a two-dimensional mechanical model of polycrystalline shape memory alloy is constructed on the bases of the crystal plasticity and the deformation mechanism of shape memory alloy. In such a model, the orientation of crystal grain in the polycrystal and the loading direction can be considered. The deformation behaviors under some complex loading conditions are calculated with the model, and the results show that they are in good qualitative agreement with the experimental results.     

形状记忆合金的应用

形状记忆合金是一种新型的功能材料,目前在许多领域都得到了应用,本文主要介绍了形状记忆合金在机械,电子以及医学领域的应用。     

镁合金低周疲劳寿命预测模型探讨

通过铸造镁合金AZ91D和变形镁合金AZ31B室温环境下应力控制的低周疲劳试验,采用Basquin模型、SWT模型、应变能-寿命模型等模型进行了镁合金低周疲劳的寿命预测。在此基础上,基于连续介质损伤力学的不可逆热力学理论,将镁合金的低周疲劳损伤视为一个不可逆的耗散过程,用熵来反映系统的耗散过程,并以每一次循环的平均应变增量来反映平均应力对材料的影响,提出了一种新的镁合金低周疲劳寿命预测模型。用该模型进行了镁合金的低周疲劳寿命预测,预测结果与实测结果符合较好,同时相比上述其他模型,该模型具有较好的预测效果。     

Effects of humidity and contact material on fretting fatigue behavior of an extruded AZ61 magnesium alloy

Fretting fatigue tests of the extruded AZ61 magnesium alloy with the same contact material under low and high humidity were carried out to investigate basic fretting fatigue characteristics and effect of humidity on fretting fatigue behavior. Influence of contact material was also studied by using JIS S45C carbon steel contact material. Degradation of fatigue strength due to fretting was much more significant than that due to corrosion under high humidity condition. Therefore, no effect of humidity on fretting fatigue strength was found. Reduction rate of fatigue strength due to fretting for the magnesium alloy was between those of aluminum alloys and titanium alloys. Tangential force coefficient of the magnesium alloy was rather low compared to other materials such as steels, aluminum alloys and titanium alloys. Fretting fatigue strength with the S45C contact material was inferior compared to that with the same contact material. This is mainly due to higher tangential force in AZ61/S45C contact. Fretting fatigue cracks at the edge of fretting contact region were observed to nucleate in the very early stage of fatigue life, similar to other structural materials.     

Fretting fatigue in 2XXX series aerospace aluminium alloys

This research investigated the effects of microstructural characteristics on the fretting response in 2XXX series aerospace aluminium alloys. Fretting fatigue tests were conducted to determine the influence of slip character, alloy purity, grain structure and yield strength on fretting crack nucleation and growth. Crack length measurements and micrographs of the specimens indicated there was no significant difference in the fretting response of these alloys based on their microstructural characteristics. Results also showed that fretting caused cracks to nucleate in the first 1–5% of total life which resulted in much shorter fatigue lives. Additionally, fretting normalized the nucleation time in all alloys, eliminating the differences in intrinsic fatigue nucleation resistance. This resulted in the alloys with the highest stress-life (S–N) fatigue properties exhibiting a greater reduction in fatigue strength under fretting conditions. The total fretting fatigue life appeared to be primarily determined by the fatigue crack propagation resistance of the alloys.     

Fatigue properties of fine grained magnesium alloys after severe plastic deformation

Fine grained AZ31 and AZ61 magnesium alloys produced by equal channel angular pressing (ECAP) were tested for investigating tensile and fatigue properties, including microstructure, monotonic tensile flow, fatigue life and crack growth rate. For the two alloys, the yield stress of the ECAPed sample was lower than that of the unECAPed (=as received) sample, because of the fact that the softening effect due to texture anisotropy overwhelmed the strengthening effect due to grain refinement. Grain refinement of the AZ31 and AZ61 alloys through ECAP was found not to be significantly effective in increasing fatigue strength.     

单晶硅微构件力学特性片上测试系统

设计一种集成静电梳状驱动器和测试结构，专用于单晶硅微构件断裂、疲劳性能测试的片上测试系统。详细介绍测试系统的结构和工作原理。对静电梳状驱动器的驱动电压一驱动力关系、结构刚度以及谐振频率进行计算。利用MEMS（micro-electro-mechanical system）体硅工艺制造该测试系统，加工得到的测试系统在显微镜工作台上进行静态和动态弯曲实验，并将实验结果与ANSYS分析结果进行对比。结果表明，该测试系统性能稳定，能够实现对单晶硅微构件的弯曲断裂和疲劳测试。