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。     

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。     

基于形状记忆合金的微小型光热驱动马达

在分析了形状记忆合金双程记忆效应原理的基础上,采用铜锌铝双向记忆合金片,设计并加工制作了两种微小型光热驱动马达,对其进行了驱动实验研究.研究结果表明,用输出波长为1064nm的YAG脉冲激光作为光热驱动马达的驱动源,在适当的输出功率和频率下,棘轮棘爪型光热驱动马达可获得较精确的步距,齿轮传动型光热驱动马达可获得较高的转...     

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。     

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.     

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.     

TiNi形状记忆合金与不锈钢钎焊接头的微观组织与性能

采用含Ag50％~68％、Cu10％~30％、Zn12％~20％、Sn0％~10％的银基钎料,通过激光钎焊,改变钎焊 有效热输入(激光输出功率和钎焊时间),研究了TiNi形状记忆合金与不锈钢异质钎焊接头的微观组织和性能。结 果表明:AgCuZnSn钎料对TiNi形状记忆合金和不锈钢的润湿性较好,钎焊接头界面平整、致密,与TiNi形状记 忆合金形成的界面反应层较窄,而与不锈钢形成的界面反应层较宽。钎焊有效热输入对TiNi形状记忆合金热影响 区组织和性能影响较大。钎焊有效热输入量过高,将导致TiNi形状记忆合金侧热影响区组织晶粒粗大、硬度降低、 塑性提高。严格控制钎焊工艺参数可以获得具有较高抗拉强度、形状记忆效应和超弹性的TiNi形状记忆合金与不 锈钢钎焊接头。     

Evolution of martensite start condition in general thermomechanical loads of Fe-based shape memory alloy

The martensitic transformation condition in an Fe-9%Cr-5%Ni-14%Mn-6%Si polycrystalline shape memory alloy is investigated during non-proportional tensile/compressive-torsional loading. The initial martensite start condition is not governed by the von Mises-type condition in the stress–temperature space. A linear temperature dependence of the martensite start stress is observed. The martensite start stress increases, both in the initial loading and in the subsequent loading, with the progress of prior martensitic transformation. The concept of linear hardening in plasticity explains well the experimental results. On the contrary, the subsequent martensite start stress returns to the initial value, meaning the alloy exhibits the softening while the reverse transformation progresses.     

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。     

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.     

TiNi形状记忆合金/钛合金异种材料激光焊

由于TiNi合金与钛合金的物理和化学性能差异较大,故其焊接性较差,焊缝区易形成大量的金属间化合物并产生裂纹。为实现上述材料的良好连接、提高接头性能,本文对采用激光焊连接0.2mm厚TiNi形状记忆合金和TC4钛合金异种材料进行了探索。分别采用直接对接焊和手工填丝焊的方法,研究了焊接接头的微观组织和力学性能。结果表明,直接对接焊时焊缝中心产生了纵向裂纹;手工填丝焊则通过合适的焊接工艺,改善了焊缝成形,避免了裂纹的产生。较优的焊接工艺参数为功率百分比18%、脉冲宽度3ms、脉冲频率3Hz;在界面区,Ni与TC4形成的过渡层宽度约为2μm,Ni与TiNi形成的过渡层宽度约为0.5μm。接头最大抗拉强度为332MPa,断裂位置发生在靠近TiNi侧的熔合线附近。     

添加Re及Zr对CuAlMnZn合金弹性回复率的影响

介绍在CuAlMnZn形状记忆合金中添加适量的Re和Zr,在经过800℃保温10min,冷却至585℃保温150min,水淬至室温的热处理条件后,其弹性恢复率得到明显的改善.Re和Zr可起到细化晶粒的作用,从细化效果看,Zr的细化效果明显优于Re.而且Zr还可以提高马氏体相变温度.     

A novel shape memory alloy actuated soft gripper imitated hand behavior

The limited length shrinkage of shape memory alloy (SMA) wire seriously limits the motion range of SMA-based gripper. In this paper, a new soft finger without silicone gel was designed based on pre bent SMA wire, and the finger was back to its original shape by heating SMA wire, rather than relying only on heat exchange with the environment. Through imitating palm movement, a structure with adjustable spacing between fingers was made using SMA spring and rigid spring. The hook structure design at the fingertip can form self-locking to further improve the load capacity of gripper. Through the long thin rod model, the relationship of the initial pre bent angle on the bending angle and output force of the finger was analyzed. The stress-strain model of SMA spring was established for the selection of rigid spring. Three grasping modes were proposed to adapt to the weight of the objects. Through the test of the gripper, it was proved that the gripper had large bending amplitude, bending force, and response rate. The design provides a new idea for the lightweight design and convenient design of soft gripper based on SMA.     

Effect of surface treatment by ceramic conversion on the fretting behavior of NiTi shape memory alloy

Three types of surface-treated NiTi samples, M-1 (700 °C/0.5 h), M-2 (650 °C/1 h) and M-3 (400 °C/50 h), were prepared by ceramic conversion treatment under different conditions. The effect of the surface treatment on the fretting behavior of NiTi alloy was investigated in the Ringer’s solution by using a horizontal servo-hydraulic fretting apparatus. The experimental results indicated that the surface layer of the low temperature (400 °C) treated samples M-3 was dominated by a single TiO₂ layer, while the high temperature (650 and 700 °C) treated samples M-1 and M-2 consisted of surface TiO₂ layer followed by a TiNi₃ layer. These surface layers were found to have a strong effect on the fretting behavior of the NiTi alloy in terms of changes in the shape of the curves of the tangential force (F _t) versus displacement (d), the fretting regimes and the damage mechanisms involved. The stress-induced reorientation of martensite bands in the NiTi alloy could decrease the slope of the F _t–d curve and thus increase the elastic accommodation ability of the NiTi plate against 1Cr13 steel ball pair. However, since the surface-treated layers could suppress the martensite reorientation in the NiTi substrate and thus decrease the elastic accommodation ability of NiTi, the gross slip started at a smaller displacement amplitude for the surface-treated NiTi samples than for the untreated one. The main wear mechanism of the as-received NiTi alloy in slip regime was adhesion and delamination, while the major damage to the high temperature treated NiTi samples M-1 and M-2 was determined as the spallation of surface-treated layers. Due to the high bonding strength of the surface-treated layer with NiTi substrate, the low temperature treated NiTi samples M-3 showed the best fretting wear resistance in all samples tested.     

Pseudoelastic behaviour of shape memory alloy beams under pure bending: experiments and modelling

The moment–curvature hysteresis loops (for single cycle) under pure bending were experimentally determined for Cu–Al–Be single crystal, Ni–Ti and Cu–Zn–Al polycrystal samples using specially designed device. The comparison with the theoretical loops is presented for linear strain-hardening and ideal pseudoelasticity models discussed in (Int. J. Mech. Sci. 2001;43:1339). All theoretical constants were determined using simple-tension data and thermodynamical identities. The tensile–compression dissymmetry effect is accounted for and non-linear differential equation describing the motion of neutral plane is derived for beams with arbitrary symmetric cross-section. The evidence of dissymmetry effect in Cu–Al–Zn is provided by application of metallographical and mechanical techniques. But the experiments and modelling have shown that the tension/compression asymmetry has in fact little influence on the moment–curvature responses on SMA beams.     

Theory and comparison of the effect of composite and shape memory alloy stiffeners on stability of composite shells and plates

The effects of composite and shape memory alloy stiffeners on stability of composite cylindrical shells and rectangular plates subjected to a compressive load are compared. The governing equations for reinforced cylindrical shells are developed based on the Love first approximation theory and smeared stiffeners technique. It is shown that composite stiffeners are more efficient in cylindrical shells, while shape memory alloy stiffeners may be preferable in plates or in long shallow shells. It is also proven that shape memory alloy stiffeners increase the upper and lower buckling loads, i.e. the linear buckling load and the minimum postbuckling load-carrying capacity of cylindrical shells modeled as single-degree-of-freedom systems by the same amount.     

记忆合金在汽车水箱温控器中的应用

叙述了形状记忆合金的功能特性,并介绍了NiTi形状记忆合金在汽车水箱中的应用及其优越性。     

Improvement of impact resistance of plain-woven composite by embedding superelastic shape memory alloy wires

Frontiers of Mechanical Engineering - Carbon fiber reinforced polymer (CFRP) composites have excellent mechanical properties, specifically, high specific stiffness and strength. However, most CFRP...     

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。     

多轴加载下缺口件弹塑性有限元分析及疲劳寿命预测

利用有限元分析软件ANSYS,得到了承受拉扭循环载荷的缺口试件缺口的处精确应变数值,给出了引起疲劳破坏的危险点。在临界平面法的基础上,考虑到法向正应变对疲劳寿命的影响,建立了一个新的多轴疲劳寿命预测模型,该模型可以较好地预测缺口试件的疲劳寿命。