NiTi形状记忆合金的振动主动控制研究

以高分子材料梁为基体，在梁的两侧面嵌入Ｍ相状态的ＮｉＴｉ合金丝作为驱动组元，一侧面嵌入母相状态的ＮｉＴｉ合金丝作为振动感知组元；建立起振动主动控制系统，实现了系统振动主动控制的计算机仿真，试验结果表明；ＮｉＴｉ形状记忆合金可灵敏地感知系统振动，在低频范围内，可有效抑制振动；试验结果验证了计算机仿真结果的正确性，提出通过增加组内ＮｉＴｉ丝的可控数量，可有效地提高ＮｉＴｉ合金控振频率上限，探讨了ＮｉＴ     

NiTi形状记忆合金振动感知与主动控振研究

分析了复合于基体材料或嵌入机械结构中的ＮｉＴｉ丝对动、静应变的感知性能，基于ＮｉＴｉ形状记忆合金的振动感知和驱动特性，实现了机械系统振动的智能化控制，建立起机械系统的动力学模型。基于机械系统参数时变的特点，应用时频分析方法很好地描述了机械系统非平稳振动响应的过程，结果表明，ＮｉＴｉ形状记忆合金可灵敏地感知动、静应变，并可迅速作出反应，有效控制振动。     

形状记忆合金耗能阻尼器的阻尼特性理论分析

研究了形状记忆合金记忆效应和相变伪弹性的热力学特性，并依据热力学本构关系建立了形状记忆合金耗能阻尼器的热力学平衡方程，利用MATLAB编制的仿真软件对NiTi丝阻尼器的一个实例进行了仿真计算。计算结果表明形状记忆合金具有明显的阻尼特性，适用用于制作结构振动控制的阻尼器件。     

具有SMA层的夹层板的振动和阻尼特性分析

根据夹层理论建立具有等厚SMA层的夹层矩形薄板的横向振动方法,利用复模量法分析SMA的超弹性效应对板的稳态受迫振动应的影响,利用SMA分段线性应力－应变模型简化SMA的超弹性本构特征,通过数值计算分析结构的稳态响应特性和阻尼特性,以及其各种参数的作用规律。     

NiTi形状记忆合金梁的变形特性

针对形状记忆合金材料拉压不对称性,结合梁的纯弯曲理论,研究了NiTi形状记忆合金梁非线性弯曲问题,建立了截面应力、变形量、相变区百分含量表达式,并对简支和悬臂两种梁进行数值求解.结果表明:随着弯矩的增大,中性层先向受压侧移动,后移向受拉侧;在同一弯矩作用下,梁的最大挠度值、曲率、变形量以及相变百分含量随着拉压不对称系数的增大而减小,拉压不对称系数越大材料越不易发生相变.     

宽温区内CuAlNi合金阻尼特性的研究

本文通过内耗、电阻、弹性模量和零点漂移随温度的变化（０～８５０℃）考察了ＣｕＡｌＮｉ合金中、沉淀相和相变对阻尼特性的影响．升温过程Ｑ－１－Ｔ曲线上，出现四个内耗峰，峰温分别为：６２℃、５６２℃、７６０℃、８２０℃．降温过程Ｑ－１一Ｔ曲线上也出现四个内耗峰，峰温分别为：８３０℃、７６７℃、５８４℃和３０℃．为了探讨其内耗机理，还进行了Ｘ线衍射和金相观察．     

NiTi薄膜对压电陶瓷材料阻尼性能的影响

采用磁控溅射法在压电陶瓷（PZT）基体上沉积形状记忆合金NiTi薄膜,经过600 °C晶化而制备出PZT/NiTi异质复合阻尼材料,采用X射线衍射仪和扫描电子显微镜等观察分析复合阻尼材料的物相组成及异质间的结合状态,并用相位法评价复合材料的阻尼性能.结果表明,PZT/NiTi异质复合阻尼材料的阻尼性能与PZT类似,但在频率为1.1~1.2 kHz时,其内耗曲线中出现了一个稳定平台.     

基于形状记忆合金的结构振动控制研究与展望

在介绍了形状记忆合金几种重要特性的基础上,综述了国内外基于形状记忆合金的结构振动控制研究现状,指出了形状记忆合金用于结构振动控制有待解决的一些关键问题,并展望了形状记忆合金在土木结构振动控制中的应用背景。     

阻尼叶片振动特性的优化研究

为了把“接触器端面正压力存在一个可使得响应最小的最佳值“的理论变为实际可行的操作,通过将最优化理论与阻尼叶片动力特性计算相结合,运用鲍威尔惩罚函数法,以系统在不同激振频率下叶顶响应位移的最大值为目标函数,通过调整相邻阻尼器之间的间隙和安装位置,以及阻尼器的结构尺寸如直径、厚度、宽度和位置等系统结构参数,使系统具有优良的动力特性,并结合某厂的900等级叶片进行了具体的优化研究。研究结果表明,优化后叶片振动响应从0．3631mm降低到0.0857mm,,使叶片获得了最优的振动特性,提高了振动安全性。     

NiTi形状记忆合金的性能测试

研究了Φ0.5mm、Φ0.2mm的NiTi记忆合金丝的制备工艺,并对其进行了力学—热学性能的测试,得到了应力、应变、温度和相变相互之间的函数关系曲线,为NiTi记忆合金丝在自适应结构中的应用奠定了基础。     

工程结构的SMA超弹性阻尼研究

分析了形状记忆合金(SMA)超弹性阻尼减振技术的机理，介绍了国外对于形状记忆合金超弹性阻尼的研究成果．通过试验研究了温度、加载频率、循环次数及预变形等因素对国产NiTi合金丝的超弹性阻尼的影响．研究结果表明：①形状记忆合金的超弹性温度区间在50℃左右，阻尼性能对温度的敏感性较小；②加载频率对形状记忆合金的超弹性阻尼有一定影响，但在工程结构常用的频率范围内基本保持稳定；③循环次数在一定程度上影响形状记忆合金的超弹性行为，但在数个循环周期以后，基本趋于稳定；④通过施加预应变，形状记忆合金的超弹性阻尼性能大为改善．因此利用SMA的超弹性阻尼特性可以研制出性能良好的耗能减振装置，有效地改善和提高土木工程结构的性能．     

Low-cost (ZrCu)50-xTax high temperature shape memory alloys showing excellent shape memory effect

ZrCu-based alloys, as one of the most potential high-temperature shape memory alloys, show quite high martensitic transformation temperature, relatively low price for the raw materials, and good casting fluidity. In this work, the martensitic transformation (MT) and shape memory effect of (ZrCu)_50-xTa_x high-temperature shape memory alloys were systematically investigated. Both X ray diffraction and SEM backscattered electron image demonstrated the coexistence of the main phase monoclinic martensite phase and the second phase Ta₂Cu. SEM results also revealed that increasing Ta content resulted in a larger volume fraction of Ta₂Cu phase. Differential scanning calorimetry results showed that the MT temperatures remarkably increased with Ta addition. The ductility of the (ZrCu)_50-xTa_x alloys was reduced to some degree with increasing Ta content. The shape memory effect was improved significantly, in which (ZrCu)₉₈Ta₂ alloy showed the 6.19% maximum recovery strain during 8% pre-strain under compression at 25 ?°C.     

TiNi形状记忆合金回复力模型

通过修正Clausius Clapeyron方程 ,使之在马氏体分数不断变化的条件下仍然适用 ,并在此基础上建立了TiNi形状记忆合金的回复力模型 ,模型中的参数均可通过实验确定 .利用此模型 ,使用典型的TiNi形状记忆合金性能参数 ,计算得到了TiNi形状记忆合金回复力与温度的关系曲线 ;与实验测试曲线的对比表明 ,本模型在大的预应变条件下与实验结果是吻合的     

TiNi形状记忆合金弹性耦合系统的驱动特性

采用将预应变TiNi合金与不同刚度系数k的偏置弹簧相串联的方法,对TiNi合金弹性耦合系统的驱动特性进行了研究。结果表明,随k值的增加,TiNi样品达到逆相变结束时的输出应变、应力温度范围逐渐变大,最大回复力逐渐增大,但驱动行程减小;样品的应力与应变之间呈线性关系,二者的比值取决于k;预应变量较大的样品,其回复应力随温度的变化率较大。通过配置偏置弹簧的刚度系数,可以控制样品输出的最大应力和最小应变,有效防止耦合系统过载。     

生理盐水中TiNi基形状记忆合金耐蚀机理研究

采用电化学测试技术对 Ti Ni基形状记忆合金在生理盐水中的腐蚀机理进行了研究 .结果表明 ,Ti Ni合金与 Ti Ni Cu合金相比 ,阳极钝化区拓宽、孔蚀电位正移、腐蚀率减小 .通过EDX分析和 SEM观察发现 ,Ti Ni基形状记忆合金蚀孔内存在富 Ti贫 Ni的 Ti2 Ni析出相 ,是萌生孔蚀的敏感位置 .在生理盐水中 Ti Ni Cu合金的耐蚀性比 Ti Ni合金劣 ,是由于 Ti Ni Cu合金存在不同晶体结构区域 ,造成电化学性质不均匀 ,加之晶界疏松状态的 Cu的表面富集 ,促进阳极溶解过程所致     

Surface nanostructures orienting self-protection of an orthodontic nickel-titanium shape memory alloys wire

Shape memory alloys (SMA) have been applied to a wide variety of applications in a number of different fields such as aeronautical applications, sensors/actuators, medical sciences as well as orthodontics. It is a hot topic to enhance the anti-corrosion ability of orthodontic wires for clinical applications. In this letter, a very nice fractal structure, micro-domains with identical nanometer sized grooves, was ob- tained on the surfaces of the orthodontic wires with an oxygen plasma and acid corrosion. The concave parts of the grooves were dominated by titanium and convex parts were the same as the bulk wires. The micro-nano fractal structure generated a hydrophobic surface with the largest contact angle to water being about 157°. The titanium dominated nanolayer and the hydrophobicity of the surface resulted in jointly the great improvement of the anti-corrosion ability of the orthodontic wires. Because the fractal structures of the wires were formed automatically when they immersed in acidic environment, hence, the self-protection of the oxygen plasma-treated orthodontic wires in acidic environment indicates their potential applications in orthodontics, and should be also inspirable for other applications of SMA materials.     

TiNi形状记忆合金断裂机理的原位拉伸研究

用SEM原位拉伸实验对TiNi形状记忆合金试样的断裂过程进行了研究和分析．结果表明,TiNi形状记忆合金的断裂与钢的脆性解理断裂不同．TiNi形状记忆合金的断裂受解理机制和孔洞在第二相颗粒处的形核、长大、连接机制控制．这两种材料失效机制共同作用,其中哪一种占统治地位取决于诸多因素．应力诱发马氏体相变对TiNi形状记忆合金的断裂具有重要的影响．     

Martensite transformation, mechanical properties and shape memory effects of Ni-Mn-In-Mg shape memory alloys

The martensite transformation(MT), mechanical properties and shape memory effect(SME) of(Ni_(50)Mn_(35)In_(15))_((1-x))Mg_x(x = 0%, 0.08%, 0.3%, 0.6% at%) alloys were comprehensively investigated. The results showed that due to Mg doping the MT temperature shifted to higher temperatures and a worm-like secondphase precipitated at grain boundaries and inside the grains. With increasing Mg content, the amount of precipitates gradually increased, the thermal hysteresis was almost invariant, and the SME was not obviously affected at 3% pre-strain, even when the volume of the second phase reached up to 28.75%. Compressive stress and strain experiments showed that both the strain and strength of the Ni-Mn-In-Mg alloys were improved substantially(by 46.9% and 53.4%, respectively, at x = 0.6%) compared with those of the pure Ni_(50)Mn_(35)In_(15) alloy; this effect is nearly the same as that achieved by the directional solidification method. Because Mg is nonmagnetic, the magnetization difference of the alloy with Mg doping is much lower than that of the alloy without Mg doping. Overall, the results confirm that adding a small amount of Mg is a potentially viable method for improving the mechanical properties of Ni-Mn-In alloys without adversely damaging their functional properties.     

热处理对CuAlNiMnTi形状记忆合金相变滞后的影响

用电阻法、金相分析、电镜分析及Ｘ射线衍射等研究了热处理对ＣｕＡｌ－ＮｉＭｎＴｉ形状记忆合金相变滞后（Ａｆ—Ｍｓ）的影响．研究结果表明：淬火合金时效处理时，相变点急剧下降，时效初期相变滞后明显增大，后趋于稳定．淬火合金６００℃中温处理时，相变点下降，相变量减小．而热弹性马氏体相变类型则从Ｉ型转变到Ⅱ型，然后再转变到Ｉ型；伴随着热弹性马氏体相变类型的变化，相变滞后开始降低，然后增加．这是因为时效处理时析出ＮｉＡｌ基相，中温处理时析出ａ相所致．