Effect of chemical component on shape memory effect of Fe-Mn-Si-Ni-C-RE shape memory alloy

Effect of chemical component on shape memory effect (SME) of Fe-Mn-Si-Ni-C-RE shape memory alloys was studied by bent measurement, thermal cycle training, SEM etc. Results of study indicate that the alloys with high Mn content (25%) appeare better SME, especially in lower strain. SME improves evidently when Si is higher content, especially it‘s range firm 3% up to 4%.But brittleness of Fe-Mn-Si-Ni-C-RE alloy increases by increasing the Si content. SME of the alloy is weakening gradually as carbon content increases under small strain (3%). But in the condition of large strain (above 6%), SME of the alloy whose carbon content ranges from 0.1% to 0.12% shows small decreasing range, especially of alloy with the addition of compound RE.     

Damping performance of Cu-Zn-Al shape memory alloys in engineering structures

The stress strain curves of two CuZnAI shape memory alloys which have the martensltic transformation temperatures of 50℃ and-10℃ respectively, were measured by using electronic material tester after treated by different heat-treatment conditions. The results show that the area enclosed by hysteresis loop of the CuZnAI shape memory alloy in martensltic state is much larger than that of the alloy in austenltic state with super-elasticity at room temperature. Therefore, the former has better vibration attenuation effect. After being oil-quenched, waterquenched, and step-quenched, the CuZnAI alloy takes on more stable shape memory effect, better super-plasticlty and superelasticity (pseudoelasticity). A CuZnAI shape memory alloy damper was designed, produced and installedto a 2-layer frame structure. In addition, the vibration experiments were made by dynamic data collecting analysis meter. The velocity of vibration attenuation of frame structure with CuZnAI shape memory alloy damper is much faster than that without it. And with the help of CuZnAI shape memory alloy damper, the attenuation period reduces to 1/10 of the original.     

Fe—Mn—Si基形状记忆合金及其应用

介绍了形状记忆合金的简要发展史,Fe-Mn-Si合金的形状记忆机理以及合金的主要元素组成,各成分的作用,提高记忆的方法,分析了其应用情况和前景。     

双程形状记忆效应的唯象动力学模型

构造可以用于描述一维结构的形状记忆合金（SMA）的双程形状记忆效应的唯象动力学模型. 该模型基于与形状记忆合金中热弹性相变有关的唯象理论,将应力场和热场下的滞回环曲线视为马氏体相变和马氏体变体重构在宏观层面上的表现. 为了模拟温度诱发的相变,构造非凸自由能函数,使得函数的每个局部平衡对应于相变过程中的一个相. 在外部负载（力或者热）的作用下,可以通过模拟系统状态（应变）在不同平衡态之间的转变,研究温度诱发的相变. 相变动力学的控制方程采用拉格朗日方程,以非线性微分方程来表示. 利用非线性常微分方程描述单程形状记忆效应,通过对不同相变过程的加权组合描述双程形状记忆效应. 开展有关力和热负载下的数值实验,模拟热和应力诱发的相变以及热负载下与单程形状记忆效应和双程形状记忆效应有关的滞回环,模拟马氏体重构所导致的单滞回环以及超弹性效应所引起的双滞回环. 从实验结果可以看出,双程形状记忆效应及超弹性效应均可以被提出的模型成功捕捉,验证了该模型的描述能力.     

Fe－Mn－Si形状记忆合金研究进展

对近年来Ｆｅ－Ｍｎ－Ｓｉ合金形状记忆效应的影响因素及工程应用的研究结果进行了评述，并对Ｍｎ、Ｓｉ元素，母相强化及热－机械训练对记忆效应的影响进行了讨论     

Fe-Mn-Si形状记忆合金的记忆性能分析

铁基形状记忆合金由于具有优良的形状记忆效应、价格低廉以及加工性能好等优点引起了广泛重视。对Fe-Mn-Si形状记忆合金的形状记忆机制、形状记忆效应的影响因素以及应用进行了评述。     

循环加载条件下形状记忆合金丝的超弹性研究

由于形状记忆合金具有优良的力学性能,近年来在土木工程领域受到广泛关注.通过在不同的循环加载条件下对形状记忆合金丝材进行的拉伸试验,以相变应力、相变应变、弹性模量、残余应变、耗能能力等作为合金丝材的超弹性特征参数,分析这些特征参数与应变幅值、加载频率、循环次数的关系.结果表明：应变幅值和循环次数对形状记忆合金超弹性性能的影响较大,而加载频率的影响基本可以忽略,实际应用时,应根据具体情况进行试验研究并合理设计.     

The Deformation Behavior of TiNi Shape Memory Alloy under Axial Dynamic Compression

The deformation behavior of Ti-50.9at% Ni shape memory alloy under axial compression dynamic loads was investigated by an MTS 858Miru Bionic test machine. The alloy were aged at 500℃ for an hour before being machined into specimens. The compression experiments were conducted at 20℃ and the variety of dynomic loads were controlled by the strain rate, which was 3mm/min, 15mm/min, 30mm/min and 50mm/min, respectively. The experimental results indicate that in the case of 3mm/min. stress-induced martensitic transformation occurs at about 350 MPa when loading and reverse transformation at about 200 MPa when unloading, during which the aged Ti-50.9at% Ni alloy shows the recoverable nonlinear pseudoelastic strain of 4.3%with the residual strain of 1.2% reserved. With the strain rate increasing, the area encloses by loading-curve and unloading-curve, i. e stress ( strain ) hysteresis becomes smaller and smaller and the residual strain also decreases, while critical stress for inducing martensitic transformation rises. At a higher strain rate the alloy exhibits linear-like pseudoelasticity, which is up to 4.5％ .     

Influence of Predeformation on Shape Memory Effect in a Fe－Mn－Si－Ni Polycrstalline Alloy

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塑性变形条件下拉伸构件的磁记忆效应

通过对经退磁处理的光滑和切口试件在不同程度拉伸变形下的在线磁信号的测量,研究了塑性变形对磁记忆效应的影响.光滑试件在弹性和均匀塑性流动阶段磁场分布近似为斜直线,仅到颈缩后才在应力集中部位产生明显的磁场畸变;切口试件在屈服以后即出现畸变特征,基于位错理论分析了异常波波高增加的原因,利用磁信号水平线图可定性判断应力集中区破...     

NiTi形状记忆合金应变传感特性分析

阐述了形状记忆合金丝的应变传感原理.在Brinson建立的形状记忆合金一维本构模型的基础上,引入Ikuta提出的电阻率与马氏体百分含量之间的关系并对其进行简化,建立了形状记忆合金应变传感特性的理论分析模型.分析了不同温度条件、不同初始状态的形状记忆合金电阻相对变化率与应变之间的关系.并与已有试验结果进行比较,验证了该模型的有效性.结果表明,形状记忆合金可以作为应变传感元件使用,温度对形状记忆合金的传感特性有影响,设计时要根据使用温度来确定形状记忆合金的相变温度.     

多孔CuAlMn形状记忆合金的制备及其压缩特性

首次以NaCl颗粒为造孔剂利用烧结-脱溶法成功制备出了多孔CuAlMn形状记忆合金,并对其宏、微观形貌特征及压缩性能进行了研究.结果表明多孔CuAlMn形状记忆合金为三维贯通的开孔网络结构,孔洞分布均匀,孔的大小、形貌与氯化钠颗粒相似.多孔CuAlMn形状记忆合金试样的准静态压缩应力-应变曲线分为明显的弹性区、平台区及致密化区3个区域.长而平的平台区表明多孔CuAlMn形状记忆合金具有良好的压缩吸能特性.     

Microstructure and shape memory effect of Cu-26.1Zn-4.8Al alloy

The influence of processing parameters on the microstructure and shape memory effect of Cu-26.1Zn-4.8Al alloy was investigated. The treated specimens were characterized by metallography, X-ray diffraction （XRD） and transmission electron microscopy （TEM） to explain the mechanism of shape memory effect in Cu-26.1Zn-4.8Al alloy. The results reveal that the shape memory effect is markedly increased by appropriate quenching and ageing process. XRD shows that γ phase precipitates from martensite when aged at higher temperature and γ precipitates impair the shape memory effect. TEM analysis indicate that the substructure of plate-like martensite consists of twins and stacking faults.     

基于形状记忆合金的TMD半主动控制

针对建筑结构在随机荷载或风荷载作用下可能发生的频率不确定问题,特别是结构自振频率会随振幅的大小而发生漂移的非线性振动问题,提出性能可靠、构造简单的形状记忆合金SMA-TMD自适应半主动控制系统.从理论上探讨形状记忆合金在变刚度TMD控制装置中的应用,并进行相应的参数设计.同时,在研究随机荷载作用下TMD系统动力特性的基础上,结合短时傅里叶变换(STFT)设计出该系统的自适应半主动控制算法.算例表明,SMA-TMD自适应控制系统能较好地识别结构系统的时频特性,并进行有效的控制,具有性能可靠和自适应能力强等特点.该自适应控制系统较传统的TMD被动控制减震效果更好,鲁棒性更强.     

磁控形状记忆合金执行器迟滞非线性模型

针对磁控形状记忆合金执行器的迟滞非线性,利用PI模型建模思想,采用线性Play算子建立磁控形状记忆合金执行器迟滞非线性模型。根据其模型结构与神经网络结构十分相似的特点,引入神经网络进行权值训练。为了提高系统的实时性,采用遗忘因子递推最小二乘法训练权值。试验结果显示:本文方法对输出位移的最大预测误差为0.0015mm,均方差为2.2931×10-4,最大误差率为0.1593%,表明该方法能够有效地建立磁控形状记忆合金(MS-MA)执行器的迟滞非线性模型,并可以获得较高的模型精度。     

Cu—Zn—AL记忆合金的热稳定性

本文研究了Cu—Zn—Al形状记忆合金在加热过程中的稳定性。实验结果表明:Cu—Zn—Al合金记忆效应的实际使用温度决定于该合金的贝氏体转变温度,合金中的贝氏体相变至少在长大阶段是扩散控制的。Cu—Zn—Al合金中Mn元素的加入使合金中的扩散能较快地进行,因而降低了合金记忆效应的热稳定性。     

CuZnAl合金在拘束训练条件下双程记忆性能的研究

本文就Cu-25.71Zn-4.18Al合金在约束训练条件下的双程记忆性能和机理作了一些研究。结果表明:对Cu-Zn-Al合金采用拘束训练后可获得较好的双程记忆性能,双程恢复角可达70°,训练后的合金做成的元件在80℃作长时间停留双程记忆,性能稳定,热循环疲劳寿命到达15500次。拘束训练所获得的双程记忆主要与残余菱形马氏体组织有关。     

Martensitic stabilization and defects induced by deformation in TiNi shape memory alloys

Martensitic stabilization caused by deformation in a TiNi shape memory alloy was studied.Special attention was paid to the deformed microstructures to identify the cause of martensitic stabilization.Martensitic stabilization was demonstrated by differential scanning calorimetry for the tensioned TiNi shape memory alloy.Transmission electron microscopy revealed that antiphase boundaries were formed because of the fourfold dissociation of [110]B19' super lattice dislocations and were preserved after reverse t...     

拉应力对不同厚度Q345钢磁记忆信号的影响

为明确磁记忆信号与拉应力之间的对应关系和几何尺寸对试件表面磁场的影响,对Q345低合金钢不同厚度板状试件进行静载拉伸实验.利用TSC-1M-4型磁检测仪,研究3种厚度的光滑试件表面磁记忆信号在不同拉应力下的变化规律.结果表明:弹性阶段磁记忆信号与拉应力之间有较好的相关性,塑性阶段两者相关性较弱;切向磁记忆信号对试件局部屈服的表征比法向磁记忆信号更敏感,利用切向磁场的畸变性可预判试件的早期塑性变形和应力集中区;同一应力水平下,试件表面磁场强度随厚度增加而减小,但不影响其变化规律.     

煤矿砂岩SHPB动态压缩力学性能试验与分析

为研究煤矿砂岩冲击载荷作用下的动态力学特性,利用分离式Hopkinson压杆对皖北矿区祁东煤矿的砂岩试件进行冲击压缩试验,得到了试件应变率变化时程曲线和动态应力一应变曲线。试验结果表明：采用3种冲击气压加栽,入射波形均近似为梯形波;试件应变率随冲击气压提高而增大,应变率曲线中有一段近似恒应变率平台,可实现恒应变率加栽;试件动态破坏形态在低应变率下为径向外围剥落式拉伸破坏模式,在高应变率下则为颗粒状粉碎破坏模式。随应变率增加,碎块尺寸减小且碎块数量增加,具有明显的应变率效应;试件动态抗压强度与平均应变率近似乘幂关系,显示出较强的相关性。