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。     

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.     

形状记忆合金动作元件疏水阀的设计与研究

利用形状记忆合金的特性设计了一种新型的热静力式蒸汽疏水阀,本文论述了形状记忆合金疏水闪匠结构原理和动作特性,并将其与另一种热表外国籍式蒸汽疏水阀一双金属片式疏水阀进行了分析和比较。     

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...     

疏水阀形状记忆合金动作元件特性分析与设计

分析了疏水阀形状记忆合金驱动元件的受力特性。根据疏水阀在开启和关闭时的受力状况，介绍了所用形状记忆合金螺旋弹簧及其相匹配的偏压弹簧的设计方法。     

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...     

形状记忆合金螺旋弹簧的设计方法

介绍了形状记忆合金螺旋弹簧的设计原理,方法及发展现状,对三种常用的设计方法进行了讨论。     

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.     

Fabrication and AE characteristics of TINI/A16061 shape memory alloy composite

TiNi/A16061 shape memory alloy (SMA) composite was fabricated by hot press method to investigate the microstructure and mechanical properties. Interface bonding between TiNi reinforcement and A1 matrix was observed by using SEM and EDS. Pre-strain was imposed to generate compressive residual stress inside composite. A tensile test for specimen, which underwent pre-strain, was performed at high temperature to evaluate the variation of strength and the effect of pre-strain. It was shown that interfacial reactions occurred at the bonding between matrix and fiber, creating two inter-metallic layers. And yield stress increased with the amount of pre-strain. Acoustic Emission technique was also used to nondestructively clarify the microscopic damage behavior at high temperature and the effect of pre-strain of TiNi/A16061 SMA composite.     

Toughness and fracture mechanisms of glass fiber/aluminum hybrid laminates under tensile loading

Tensile properties and fracture toughness of monolithic aluminum (Al), glass fiber reinforced plastics (GFRPs) and glass fiber/aluminum hybrid laminates (GFMLs) were examined in relation to the fracture processes of plain coupon and single-edge-notched specimens. Elastic modulus and ultimate tensile strength of GFMLs showed characteristic dependences on the kind of Al, fiber orientation and the Al/fiber layer composition ratio. Fracture toughnesses K_C and G_C of A-GFML-UD were comparable to those of GFRP-UD and were much superior to monolithic Al. However, GFML with a transverse crack parallel to the fiber layer deteriorated largely in toughness. Microscopic observation of the fracture zone in the vicinity of the crack tip revealed various modes of micro-cracks in the respective layers as well as fiber fractures and delamination between fiber/Al layers. Such damage advances in GFMLs dependent on the orientation of the fiber layer and the Al/fiber composition ratio strongly influenced the strength and toughness of GFMLs.     

Effect of fuzzy C means technique in failure mode discrimination of glass/epoxy laminates using acoustic emission monitoring

Acoustic emission is one of the powerful techniques that can be used for in situ structural health monitoring of composite laminates. One of the main issues of AE is to characterize the different damage mechanisms from the detected AE signals. Unsupervised Pattern recognition has been one of the techniques used for the identification of a specific failure mode in composites from Acoustic emission data. Cross ply composite laminate of size 300 × 300 mm is fabricated using Vacuum bag molding. ASTM D3039 Standard tensile specimens are cut from the laminate and these specimens are subjected to uni axial tensile test under Acoustic Emission monitoring. Fast Fourier transform analysis (FFT) and Short Time Fast Fourier Transform (STFFT) analysis are performed on the Wave forms of the AE hit data obtained during the conduct of tensile test to characterize the failure modes in crossply specimens. Fast Fourier Transform enabled calculating the frequency content of each damage mechanism. In this paper Fuzzy C Mean clustering is performed for the AE parameters obtained from the test and the efficiency of this technique is being investigated using FFT AND STFFT analysis.     

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。     

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。     

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.     

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.     

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。     

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.     

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。