NiTi形状记忆合金拉伸变形失稳研究

介绍镍钛形状记忆合金发生应力诱发马氏体相变时的宏观失稳现象,研究微观晶粒内相变(材料失稳)因自催化效应逾渗到宏观水平所表现的类L櫣ders变形带演化(变形失稳),同步测量应力-应变响应、表面形貌和表面温度,跟踪了不同热-机械复合加载条件下构件力学行为的变化.从能量学角度对观察到的变形失稳现象进行理论分析.实验结果表明,宏观变形带的相貌演化与力学响应密切相关,探讨了建立该类材料的本构关系.     

形状记忆合金复合材料层合梁的弯曲

分析了一种形状记忆合金复合材料层合梁在荷载作用和温度改变下梁的曲率k与截面弯矩M及温度T的关系 ,并进一步得到在恒定温度下悬臂梁自由端挠度随外载荷变化的曲线 结果显示该层合悬臂梁具有和形状记忆合金材料相同的超弹性特性     

基于有限元计算的形状记忆合金-金属玻璃复合材料变形行为

利用有限元模拟方法,研究了拉伸-卸载预应变对形状记忆合金-金属玻璃复合材料力学行为的影响及其内在机理.结果表明:预处理应变增加,形状记忆合金-金属玻璃复合材料的屈服强度及弹性应变极限均提高,但拉伸延展性急剧下降.预应变增加导致形状记忆合金颗粒第二次加载时的变形行为由典型的马氏体相变过渡为连续的马氏体相变,甚至表现为纯马氏体相的弹性变形.这一"相变效应"的减弱甚至消失,是形状记忆合金-金属玻璃复合材料经拉伸-卸载预处理后拉伸性能退化的直接原因.     

石墨烯增强铝基复合材料的热变形本构方程研究

采用热模拟实验机对石墨烯增强7075铝合金复合材料进行高温热压缩实验,变形温度为300～450℃、应变速率为0.001～1 s^-1,分析其在不同应变速率及温度条件下的高温流变应力特征,并以实验数据为基础,通过函数拟合确定包含应变、应变速率和温度等变形参数的双曲正弦本构方程。研究结果表明：铝基复合材料热压缩变形时流变应力随应变增加迅速增大,达到峰值应力后略有下降且出现锯齿状波动;给出的双曲正弦本构方程可以较好地描述流变应力与应变、应变速率及温度之间的关系,计算值与实验值吻合良好。     

混杂复合材料受压状态下的基体剪切破坏

剪切破坏是混杂复合材料受压破坏的关键因素。本文分析了这种剪切破坏,建立了基体破坏的应力分析,并且指出了混杂效应的作用。     

基于形状记忆合金的阻尼减振研究

介绍了形状记忆合金（SMA）的一种本构关系，简要讨论了形状记忆合金的阻尼特性，并在框架上进行了振动试验，试验结果表明，形状记忆合金可有效的改变结构的阻尼大小，是一种很好的阻尼材料，其在振动控制领域内具有广阔的应用前景。     

形状记忆合金在结构变形和裂缝控制中的应用

形状记忆合金是一种具有全新功能的材料,本文讨论了它的力学性能、行为特点、本构关系、热力学性能及其在结构变形和裂缝控制中的应用,并简要介绍了它在应用中存在的问题和改进方法．     

混杂SIFCON弯曲抗拉性能试验研究

主要报道在采用SIFCON工艺成型的高含量钢纤维混凝土中，加入PP改性聚丙烯纤维的复合材料弯曲抗拉性能试验的试验结果，并讨论在荷载作用下，试件挠曲率和平截面转动的变形性能。     

形状记忆聚合物复合材料梁的弯曲变形

基于形状记忆聚合物（SMP）材料研制了热激励主动变形的纤维增强形状记忆聚合物复合材料（SMPC）,对其动态力学性能进行了测试分析,应用有限元模拟分析法和层合板理论,得到SMP和SMPC悬臂梁的弯曲变形与刚度变化曲线。分析表明：SMPC材料抵抗变形的能力高于SMP材料。在等温度条件下,SMP梁和SMPC梁的变形与载荷呈线性关系;在等载荷条件下,SMP梁和SMPC梁的变形与温度呈非线性关系。SMPC的刚度特性使其在高温下应用领域得到拓展。     

Constitutive behavior of Ni-Ti shape memory alloy under hot compression

Constitutive behavior of nickel-titanium shape memory alloy (Ni-Ti SMA) under hot deformation was investigated by means of the compression tests and the linear fitting method. Based on the true stress-strain curves of Ni-Ti SMA under compression at the strain rates of 0.001-1s -1 and at the temperatures ranging from 600 to 1 000℃, the constitutive equation of Ni-Ti SMA with respect to the Zener-Hollomon parameter was established according to the high stress level and the low stress level at various temperatures so as to more accurately describe the deformation behavior of Ni-Ti SMA during hot working. Dynamic recovery and dynamic recrystallization of Ni-Ti SMA occur under hot compression, which lays the theoretical foundation for understanding the constitutive behavior of Ni-Ti SMA.     

Constitutive model for shape memory alloy torsion actuator

Shape memory alloy ( SMA) torsion actuator is one of the key approaches realizing adaptive wings in airplanes. In this paper,the actuator is made up of SMA wires and a thin-walled tube,in which the SMA wires are twisted and affixed around the surface of the tube at an angle referenced to the center axis of the tube. A thermo-mechanical constitutive model is developed to predict the thermo-mechanical behaviors of the SMA torsion actuator based on the knowledge of solid mechanics. The relationship between the torsion-angle and tem- perature is numerically calculated by using the thermo-mechanical constitutive model coupled with the SMA phase transformation model developed by Zhou and Yoon. The numerical results are compared with the relative experimental results finished by Xiong and Shen. Influences of the twist-angle of SMA wires and geometrical factors on the primary actuation performances of the SMA torsion actuator are also numerically investigated based on the thermo-mechanical constitutive model coupled with the SMA phase transformation model developed by Zhou and Yoon. Results show that the thermo-mechanical constitutive model can well predict the thermo-mechanical behaviors of the SMA torsion actuator.     

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.     

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。     

形状记忆合金在结构抗震控制中的应用

讨论了形状记忆合金的本构关系,综述了这种全新功能材料的行为特点,热力学性能主其在结构抗震控制和裂缝控制中的应用,并简要介绍了在控制应用中存在的问题以及改进方法。     

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.     

SMA被动隔震装置及其阻尼性能研究

形状记忆合金(SMA)在伪弹性阶段具有较好的阻尼性能，利用这一特点，本文提出了一种SMA被动隔震装置，通过对SMA元件的合理布置，使隔震体系获得可观的耗能能力和震后复位的功能，为了验证上述体系的有效性，本文根据SMA的热力学本构关系，建立了热力学非线性方程的求解方法，并且绾制了计算机分析程序进行了实例计算，结果表明，上述隔震体系具有较好的工作性能。     

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％ .     

Low Velocity Impact Response Analysis of Shape Memory Alloy Reinforced Composite Beam

The low velocity impact responses of shape memory alloy （ SMA ） reinforced composite beams were analyzed by employing the finite element method. The finite element dynamic equntion was solved by the Newmark direct integration method, the impact contact force was determined asing the Hertzian contact law, and the influence of SMA .fibers on stiffiwss matrix is studied. Numerical results show that the SMA fibers can effectively improve the low velocity impact response property of composite beam.