形状记忆合金驱动的曲柄滑块机构多目标优化设计

提出了一种应用于水下机器人方向舵、滑块为原动件的曲柄滑块传动机构,形状记忆合金差动驱动是该机构的突出特点.分析了形状记忆合金差动驱动的曲柄滑块机构运动机理,基于形状记忆合金驱动器的变形能力和力学性能,采用多目标优化设计理论和算法,对形状记忆合金差动驱动的滑块行程和作用在滑块上的初始驱动力进行了综合优化,得到了曲柄滑块机构的结构优化参数,同时为形状记忆合金差动驱动器的性能参数设计提供了理论依据和设计准则.虚拟样机仿真试验验证了机构良好的驱动和传动性能.     

形状记忆合金驱动的微型管道机器人机械结构设计

微型管道机器人是通过利用形状记合金(Shape Memory Alloy,简称SMA)制成的压缩弹簧在加热和冷却过程中释放的能量而行进的.主要由形状记忆合金弹簧,磨擦弹簧片,Maxon伺服直流电机等构成.该机器人可以蠕动的方式通过直为(50～80)mm的各种材料的管道,并可顺利通过曲率半径为管道直径1.2倍的弯道,包括U型、T型等管道.其主要特点是结构紧凑、重量轻、制造加工容易,能在恶劣环境中工作,可用于在灾害事故中寻找人或物,或在细长管道中查找故障,而且可将机器人做成系列产品.     

Design parametric study based fabrication and evaluation of in-pipe moving mechanism using shape memory alloy actuators

An in-pipe moving mechanism based on design parametric study of dynamic characteristics of clamping or moving module comprising shape memory alloy (SMA) spring actuators has been fabricated and evaluated under in-pipe condition. Conventional in-pipe moving mechanisms for pipe inspection, driven by electromagnetic motors, have large volume and mass. The SMA actuator can be an alternative for a small-sized in-pipe moving mechanism due to its great power-to-weight ratio and simple structure. Therefore, spring type SMA actuators are selected to fabricate an inchworm-like moving mechanism that consists of clamping and moving modules. For selection of proper operating type (a bias type or a differential type) for clamping module and moving module, displacements and dynamic characteristics of each operating type have been investigated. Based on experimental results, we decide some design parameters such as wire diameters, spring diameters and the numbers of turns of SMA spring actuators and fabricate the in-pipe moving mechanism according to the designed results. A moving speed of 34 mm/min and traction force of 0.4 N have been obtained from the driving experiment in a pipe with the diameter of 39 mm.     

Predictive position and force control for shape memory alloy cylinders

In this paper, a linear lightweight electric cylinder constructed using shape memory alloy (SMA) is proposed. Spring SMA is used as the actuator to control the position and force of the cylinder rod. The model predictive control algorithm is investigated to compensate SMA hysteresis phenomenon and control the cylinder. In the predictive algorithm, the future output of the cylinder is computed based on the cylinder model, and the control signal is computed to minimize the error and power criterion. The cylinder model parameters are estimated by an online identification algorithm. Experimental results show that the SMA cylinder is able to precisely control position and force by using the predictive control strategy though the hysteresis effect existing in the actuator. The performance of the proposed controller is compared with that of a conventional PID controller.     

Preliminary study of micro-scale abrasive wear of a NiTi shape memory alloy

Nitinol (NiTi), a nearly equiatomic nickel-titanium alloy is known for its unique shape memory and superelastic properties, which result from martensitic transformations. It is the material of choice for numerous biomedical applications such as endovascular stents, vena cava filters, dental files and guidewires for non-invasive surgery, etc. Micro-scale abrasion tests (MSATs) have been performed on the NiTi shape memory alloy, so as to evaluate the influence of different commercial abrasives such as silicon carbide, alumina and glass on the wear behaviour. The aim of the work was the selection of the most effective abrasive for cleaning the inner surface of laser-cut cardiovascular stents. Abrasive particles have been characterised by X-ray diffraction, SEM and EDS before and after MSATs. Worn surfaces have been studied by stylus profilometry, SEM and atomic force microscopy. The effect of abrasive particle hardness, size and angularity on the wear behaviour has been evaluated and discussed.     

Development of a shape memory alloy multiple-point injector for chemotherapy

A medical needle is described that allows injection to take place at multiple sites through a single stab wound. This is achieved by extruding multiple, thin, and curved internal needles from a larger, straight, outer needle. The development and finite element modelling of the shape memory alloy (SMA) inner needles is presented in this paper. A non-linear elastic element model was used in this process to allow for the non-linear properties of the alloy and the large deformations that occur. The model provided maximum strain values and penetration forces for the inner needles. The deformation force on the tip of the needle was measured against displacement to confirm the predicted penetration force. Applications for the device include the treatment of liver cancer by direct injection of alcohol into the tumours.     

形状记忆合金管接头的工作原理及研究进展

形状记忆合金管接头由于安装方便，使用安全可靠等优点而受到广泛关注，本文就形状记忆合金管接头的工作原理及研究进展进行了详细的论述。     

A theoretical comparison of two possible shape memory processes in shape memory alloy reinforced metal matrix composite

Two possible shape memory processes, austenite to detwinned martensite transformation and twinned martensite to detwinned martensite transformation of a shape memory alloy have been modeled and examined. Eshelby’s equivalent inclusion method with Mori-Tanaka’s mean field theory is used for modeling of the shape memory processes of TiNi shape memory alloy reinforced aluminum matrix composite. The shape memory amount of shape memory alloy, plastic strain and residual stress in the matrix are computed and compared for the two processes. It is shown that the shape memory amount shows differences in a small prestrain region, but the plastic strain and the residual stress in the matrix show differences in the whole prestrain region. The shape memory process with initially martensitic state of the shape memory alloy would be favorable to the increase in the yield stress of the composite owing to the targe compressive residual stress and plastic strain in the matrix.     

Ultimate load and release time controllable non-explosive separation device using a shape memory alloy actuator

This paper describes a newly designed ultimate load and release time controllable non-explosive separation device which is activated by a spring-type shape memory alloy (SMA) actuator. This device is comprised of a separation mechanism consisting of a deformation module, a blocker, the housing, two release springs and a spring-type SMA actuator. Through a theoretical approach, the ultimate load of the separation device and the required force to deform the deformation module according to the thickness of the deformation module are investigated. Based on theoretical results, the specifications of an SMA actuator to deform the deformation module are determined. In order to validate theoretical result, we manufactured a separation device which has a 1mm thickness of deformation module. Subsequently, the release time test, preload test, ultimate load test, and shock test are performed respectively. As a result, the release time with 30 W of power input is 55 sec. It actuates reliably under 150 N of preload and generates a maximum shock of −11.09 G when the diameter of the SMA wire is 1.75mm. The maximum ultimate-load for 1mm thickness of aluminum deformation module is 1,510N. Conclusively, satellite designers can select proper specification such as the ultimate load, shock level and release time according to satellite requirements by simply changing the thickness of the deformation module.     

用形状记忆合金驱动的一种新型蛇形机器人

利用形状记忆合金弹簧和普通钢丝弹簧联接作为动力驱动元件设计制作的一种蛇形机器人，其动作靠电流的通、断来控制。每节均可加热、冷却，使蛇形机器人做前后、左右、转弯运动及绕攀上、下爬行。其制造成本低，能在恶劣环境中工作，特别是在水下工作，可用于在灾害事故中寻找人或物，在细长管道中查找故障，也可用在开发儿童智力玩具中。     

差动式形状记忆合金驱动器驱动性能研究

设计了一种变体机翼后缘驱动器,对几种常规加热方式进行测试、对比后,选择附着碳纤维丝加热,达到了理想加热效果。并通过升温测试及激励间隔实验,对形状记忆合金卷簧的热响应进行研究,分析了该驱动源在不同激励方式下的温升与散热特性和对输出的影响,实现了通过最优激励方式控制驱动器工作的目的,为该驱动器在后续智能控制设计方面起到了指导作用。     

Finite elements adding and removing method for two-dimensional shape optimal design

A simple procedure to add and remove material simultaneously along the boundary is developed to optimize the shape of a two dimensional elastic problems and to minimize the maximum von Mises stress. The results for the two dimensional infinite plate with a hole, are lose to the theoretical results of an elliptical boundary and the stress concentration is reduced by half for the fillet problem. The proposed shape optimization method, when compared with existing derivative based shape optimization methods has many features such as simplicity, applicability, flexibiity, computational efficiency and a much better control on stresses on the design boundary.     

Experimental study on rate dependence of macroscopic domain and stress hysteresis in NiTi shape memory alloy strips

NiTi polycrystalline shape memory alloys, when stretched, can deform through the formation and growth of localized macroscopic martensite domains. In this paper, we study the effects of stretching rate on the stress-induced domains and stress hysteresis in NiTi strips. Synchronized measurements of the nominal stress–strain curve, macroscopic domain pattern and the associated temperature field were conducted in the strain rate range of 10⁻⁴–10⁻¹/s. It was found that the nominal stress–strain curve changed from the near-isothermal plateau-type with distinct stress drops at the very low strain rate to the near-adiabatic smooth hardening-type in the high strain-rate region. The corresponding deformation mode changed from the nucleation propagation mode with a few parallelepiped martensite domains to the near-homogeneous multiple-nucleation mode with many fine alternating austenite–martensite stripes. The number of the domains (domain spacing) increased (decreased) monotonically with the strain rate and followed a power law scaling, while the stress hysteresis (or material damping capacity) changed non-monotonically with the strain rate, reaching a peak at strain rate of 2.0×10⁻³/s. We show that, though the rate dependence of both pattern and hysteresis originates from the transfer of the released/absorbed heat and the thermo-mechanical coupling, the domain spacing in the test of static air is mainly controlled by heat conduction and the hysteresis change is mainly controlled by the heat convection with the ambient.     

形状记忆合金丝的性能测试与控制系统研究

描述了SMA的一些典型特性及采用的SMA本构模型;对SMA测试方案、SMA测试平台的机械与控制系统进行了详细的分析;最后给出了SMA数据采集与控制系统的总体方案。与传统SMA测试仪相比,该平台具有成本低,结构简单,精度高,可控制等优点。该测试与控制平台为更好地监测和控制SMA的驱动行为、设计SMA驱动元件提供重要参考依据。     

新型铜基记忆合金(CuAlMnX)机械性能测试

新型铜基记忆合金（CuAlMnX）在经过布氏硬度测试、拉伸试验、超弹性回复性能测试、超弹状态下的疲劳寿命这4项机械性能的测试后。证实其综合机械性能已达到企业标准,断裂韧性优于NiTi形状记忆合金,弹性回复率、塑性等性能均优于已见报道的其它铜基记忆合金。     

Fretting wear behavior of superelastic nickel titanium shape memory alloy

The fretting behavior of superelastic nickel titanium (NiTi) shape memory alloy was studied at various displacement amplitudes on a serve-hydraulic dynamic test machine. The results showed that the superelastic properties of the material played a key role in the observed excellent fretting behavior of NiTi alloy. Due to the low phase transition stress (only 1/4 the value of its plastic yield stress) and the large recoverable phase transition strain (5%) of NiTi, the friction force of NiTi/GCr15 stainless steel pair is smaller than the value of GCr15/GCr15 pair and at the same time the Rabinowicz wear coefficient of NiTi plate is about 1/9 the value of GCr15 plate under the same fretting conditions. For NiTi/GCr15 pair, even NiTi has a much lower hardness than GCr15, the superelastic NiTi alloy exhibits superior fretting wear property than GCr15 steel. It was found that the weak ploughing was the main wear mechanism of NiTi alloy in the partial slip regime. While in the mixed regime and gross slip regime, the wear of NiTi was mainly caused by the abrasive wear of the GCr15 debris in the three-body wear mode.     

Quality improvement by using grey prediction tool compensation model for uncoated and TiAlCN-coated tungsten carbide tools in depanel process of memory modules

Small outline dual in-line memory modules (SO-DIMM) are the memory modules used in notebook computers. This study investigates the SO-DIMM accuracy and tool life using an uncoated and TiAlCN-coated tungsten carbide tool in the depanel process. During the cutting process, the tool operating time of a TiAlCN-coated tool can be extended and the surface quality of SO-DIMM at the cutting edge is better than uncoated tools based on EDS (energy dispersive spectrometer) observation. In the milling process, tool wear is a serious problem for new tools and to solve the problem of dimension variation, this study proposes the use of grey prediction tool compensation to offset the variation and enhance the quality of SO-DIMM. According to the process capability indices within the experimental scope, the quality of memory modules using uncoated and TiAlCN-coated tools using grey prediction tool compensation were shown to improve both its Ca and Cpk values. Thus, the grey prediction tool compensation method has really proven to be workable and can improve the quality of SO-DIMM.     

形状记忆合金在结构阻尼性能优化中的应用

文中研究了通过嵌入NiTi-SMA丝提高自由阻尼层结构损耗性能的方法。首先描述了普通阻尼层材料的贮能模量及损耗因子随温度变化规律。基于一维SMA的Brinson模型给出了NiTi-SMA丝受限回复应力的计算公式,建立了含NiTi-SMA丝的自由阻尼处理梁结构损耗因子的计算公式。通过数值计算揭示了含NiTi-SMA丝的聚氨脂自由阻尼处理梁的耗散特性,分析了NiTi-SMA丝含量及阻尼层厚度对自由阻尼处理梁耗散特性的影响。结果表明,埋入NiTi-SMA丝之后,阻尼结构的损耗因子得到了显著提高。     

定向凝固制备TiNi形状记忆合金的研究

利用定向凝固技术可制备出具有柱状组织的TiNi形状记忆合金.通过对力学性能测试,研究组织对TiNi合金力学性能的影响.结果表明:具有定向凝固组织的TiNi合金相对于普通铸造的TiNi合金在抗拉强度和断裂延伸率上均有一定的提高;同时C、O杂质元素对TiNi合金的性能影响很大.     

不同载荷下形状记忆合金管接头性能的有限元分析

采用形状记忆合金（SMA）的本构方程分析了管接头,考虑了不同边界和载荷对管接头系统的影响,得出了管接头系统的应力分布。结果表明,管接头的两端内边沿、中间内壁部分的交界面处均是产生裂纹或脱粘的危险部位,垫层的存在有助于提高管接头系统的连接强度。