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TiNi基高温形状记忆合金的马氏体相变与形状记忆效应 总被引:2,自引:0,他引:2
综述了Ti-Ni基高温形状记忆合金中的马氏体相变和形状记忆效应最近研究进展。Ti-Ni基高温形状记忆合金主要包括用Ti-Ni-Pd,Ti-Ni-Pt,Ti-Ni-Zr和Ti-Ni-Hf等。对Ti-Ni基高温形状记忆合金体材料、薄带和薄膜中的马氏体相变、组织结构、形状记忆效应以及超弹性性能等进行了评述和归纳。值得注意的是,通过适当的时效处理可调节相变温度,显著改善Ti-Ni-Hf高温形状记忆合金的开头记忆效应和超弹性性能,其主要原因在于时效的Ti-Ni-Hf合金中析出纳米级析出相导致基体强度升高。采取适当的制备和加工方法,提高合金的马氏体相变温度,改善合金的开头记忆效应,是当前TiNi基形状记忆合金研究的主要发展趋势。 相似文献
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形状记忆合金驱动的微执行器 总被引:7,自引:0,他引:7
以TiNi基为代表的形状记忆合金(SMA)具有做功密度大、可恢复应变应力大、驱动电压低、良好生物相容性等优点,在微执行器领域具有极为广阔应用前景。本文主要总结了TiNi基SMA丝、薄带、薄膜在微执行器方面的国内外研究应用现状,并对目前SMA在微驱动领域应用所存在的问题及其未来的发展趋势进行了分析讨论。 相似文献
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基于塑性理论的形状记忆合金本构模型、试验和数值模拟 总被引:5,自引:0,他引:5
通过拉伸试验,研究了超弹性形状记忆合金(SMA)丝在不同应变幅值反复加卸载条件下的滞回变形行为。在测得试验数据的基础上,针对目前广泛使用的SMA Graesser&Cozzarelli模型仅描述了小应变情况下SMA特性,而在大应变下SMA马氏体的硬化特性不能得到描述的问题,提出了修正的SMA本构模型,并把模型拟合结果和实验数据进行了比较分析。结果表明,模型数值拟合结果和试验数据吻合很好,可以很好地描述SMA在不同应变幅值下的应力-应变关系;且模型形式简单,概念明确,参数容易得到,具有一定的工程应用价值。 相似文献
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Runnong Huan Lonny L. Thompson 《International journal for numerical methods in engineering》2000,47(9):1569-1603
Asymptotic and exact local radiation boundary conditions (RBC) for the scalar time‐dependent wave equation, first derived by Hagstrom and Hariharan, are reformulated as an auxiliary Cauchy problem for each radial harmonic on a spherical boundary. The reformulation is based on the hierarchy of local boundary operators used by Bayliss and Turkel which satisfy truncations of an asymptotic expansion for each radial harmonic. The residuals of the local operators are determined from the solution of parallel systems of linear first‐order temporal equations. A decomposition into orthogonal transverse modes on the spherical boundary is used so that the residual functions may be computed efficiently and concurrently without altering the local character of the finite element equations. Since the auxiliary functions are based on residuals of an asymptotic expansion, the proposed method has the ability to vary separately the radial and transverse modal orders of the RBC. With the number of equations in the auxiliary Cauchy problem equal to the transverse mode number, this reformulation is exact. In this form, the equivalence with the closely related non‐reflecting boundary condition of Grote and Keller is shown. If fewer equations are used, then the boundary conditions form high‐order accurate asymptotic approximations to the exact condition, with corresponding reduction in work and memory. Numerical studies are performed to assess the accuracy and convergence properties of the exact and asymptotic versions of the RBC. The results demonstrate that the asymptotic formulation has dramatically improved accuracy for time domain simulations compared to standard boundary treatments and improved efficiency over the exact condition. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
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采用单辊旋淬法制备了3种不同组成的Fe基形状记忆合金(shape memory alloy,SMA):Fe-30Mn-6Si、Fe-30Mn-6Si-1Ni、Fe-30Mn-6Si-1Ni-1Ti。采用X射线衍射仪(XRD)、金相显微镜(OM)、扫描电子显微镜(SEM)分析了合金的成分及结构,通过拉伸实验测量合金的形状恢复率。结果表明,在Fe-30Mn-6Si合金中,除奥氏体晶粒外出现少量枝晶偏析,其二次枝晶臂间距为0.2μm。Fe-30Mn-6Si-1Ni、Fe-30Mn-6Si-1Ni-1Ti中等轴奥氏体晶粒均匀分布,且后者晶粒较大。预变形量为1%,1.5%时,Fe-30Mn-6Si-1Ni的形状恢复率高于Fe-30Mn-6Si-1Ni-1Ti;预变形量为2%时,Fe-30Mn-6Si-1Ni-1Ti的形状恢复率高于Fe-30Mn-6Si-1Ni;预变形量为3%时,Fe-30Mn-6Si-1Ni-1Ti的形状恢复率出现最大值2%。 相似文献
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文中依据固体经验电子理论[1],建立了NiTi形状记忆合金马氏体晶胞的键络模型;并就合金化元素V对其相变点Ms的影响进行了电子结构分析,为揭示该功能材料中成分-性能-结构之间的内在联系做了初步探索,从电子结构的层次上初步解释了V对NiTi合金Ms点的作用机制. 相似文献
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The influence of hafnium element’s incorporation on a Cu–xHf–13.0Al–4.0Ni (wt-%) (x?=?0.5, 1.0 and 2.0) high-temperature shape memory alloy was investigated systematically. The results show that the matrix of Cu–xHf–13.0Al–4.0Ni (x?=?0.5, 1.0 and 2.0) alloys is 18R martensite, and an orthorhombic-structured Cu8Hf3 phase is formed and distributed at the grain boundaries. The grain size is significantly reduced with increasing Hf content. The mechanical properties of Cu–xHf–13.0Al–4.0Ni (x?=?0.5, 1.0 and 2.0) alloys are improved by Hf doping due to the combination of refinement strengthening, solid solution strengthening and second phase strengthening. After heating under pre-strain of 10%, the shape memory effect of the Cu–1.0Hf–13.0Al–4.0Ni alloy reaches 5.6%, which is obviously higher than that of the Cu–13.0Al–4.0Ni alloy. 相似文献
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综述了TiNi基形状记忆合金最近的基础研究和应用研究进展。对TiNi基形状记忆合金的马氏体相变以及TiNi基高温形状记忆合金、TiNi基形状记忆合金薄膜、TiNi基复合材料以及TiNi基形状记忆合金在航空航天等领域的应用进行了评述和归纳,结合TiNi基形状记忆合金材料和应用研究取得的新进展,认为多功能化,稳定化和集成化是当前TiNi基形状记忆合金研究的主要发展趋势。最后展望了TiNi基形状记忆合金的发展前景。 相似文献
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铁磁NiMnGa形状记忆合金研究的新进展 总被引:5,自引:0,他引:5
铁磁NiMnGa形状记忆合金在磁场控制下不仅具有可与形状记忆合金相比的、大的输出应变和应力,而且具有高的能量密度和可与压电材料相比的、高的频率响应和可精确控制的特性。系统阐述了近年来铁磁Ni-Mn-Ga系统的结构、微结构、相变机理、形状记忆效应及其在应用方面的一些新的研究成果,着重澄清了一些易混淆的基本概念,并探讨了存在的问题和可能的解决途径。 相似文献
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Shape memory alloys (SMAs) are widely utilized as an actuation source in microscale devices, since they have a simple actuation mechanism and high‐power density. However, they have limitations in terms of strain range and actuation speed. High‐speed microscale SMA actuators are developed having diamond‐shaped frame structures with a diameter of 25 µm. These structures allow for a large elongation range compared with bulk SMA materials, with the aid of spring‐like behavior under tensile deformation. These actuators are validated in terms of their applicability as an artificial muscle in microscale by investigating their behavior under mechanical deformation and changes in thermal conditions. The shape memory effect is triggered by delivering thermal energy with a laser. The fast heating and cooling phenomenon caused by the scale effect allows high‐speed actuation up to 1600 Hz. It is expected that the proposed actuators will contribute to the development of soft robots and biomedical devices. 相似文献