共查询到20条相似文献,搜索用时 179 毫秒
1.
2.
3.
4.
日本大同特殊钢(株式会社)于1992年开始了用形状记忆合金作为混水阀卷簧的研究开发.当时,市场上销售的带水温自动调节功能的混水阀中,感温元件用的是导热性能较差的液体石蜡,对温度变化的响应速度较慢.暂时关水后再打开水龙头时,因进水温度变化所导致的出水温度的波动较大,可达5~10℃.用形状记忆合金卷弹簧作为感温元件可以有效地改善导热性.在混水阀中,主要利用的是形状记忆合金在相变区域内的形状回复特性,因此,必须解决相变温度的控制和产生的作用力的控制等许多技术课题. 相似文献
5.
6.
研究了一种具有损伤自修复功能的智能混凝土梁.将常温下处于奥氏体状态的形状记忆合金和内含修复胶粘剂的修复纤维管,预埋在混凝土的受拉区或易产生裂缝的位置;利用形状记忆合金的超弹性特性和受限回复产生较大驱动力的特性,控制并恢复结构、构件的变形和挠度,减轻台风、地震的冲击,提高结构的抗灾性能,确保其安全性;利用修复胶粘剂对裂缝的填充、修复特性,恢复混凝土的强度,提高结构的耐久性.试验结果表明,形状记忆合金显著的提高了梁的变形能力;一旦外力消失,梁在形状记忆合金超弹性效应的驱动下,挠度迅速恢复,裂缝闭合;试件再次受力时,经修复胶粘剂修复后的裂缝未再次开裂,而在试件中出现了新的裂缝. 相似文献
7.
8.
9.
10.
对含预置穿透分层复合材料层板开展压缩强度和压缩疲劳试验,获得结构的极限载荷,并研究层板的分层扩展特性。基于ABAQUS软件建立含穿透分层复合材料层板有限元模型,通过VCCT计算能量释放率,采用B-K准则来模拟层间分层的扩展。引入VUMAT子程序,采用改进的Hashin准则判断单元损伤;基于累积损伤理论和剩余强度理论,弱化材料性能,对含穿透分层和含紧固穿透分层复合材料层板的疲劳力学行为进行分析,讨论了紧固件等参数对层板分层扩展的影响。 相似文献
11.
《Composites Part B》2001,32(3):259-267
In this paper, the modeling, numerical simulation and experimental validation of the deformation of a composite cantilever beam actuated by shape memory alloy (SMA) wires are presented and discussed. The structural model incorporates a number of non-classical features such as laminated construction and anisotropy of constituent material layers, transverse shear deformability, distortion of the normals, and fulfillment of interfacial shear traction continuity requirement. Suitable for use in standard finite element codes, a numerical procedure is developed for solving the geometric non-linearity of the host structure and the hysteretic non-linearity of SMA wires, which is based upon the updated Lagrangian formulation. The application concerns an elastomeric beam with embedded and pre-stressed SMA wires at an offset from the neutral axis, which act as large bending actuators resulting from the thermally induced reversible transformation strains. The experiments and numerical simulation demonstrate the good predictive capability of the model proposed and the powerful role played by SMAs as large bending actuators. 相似文献
12.
Vibration characteristics of laminated composite plates with embedded shape memory alloys 总被引:1,自引:0,他引:1
Run-xin Zhang Qing-Qing Ni Arata Masuda TakahikoYamamura Masuharu Iwamoto 《Composite Structures》2006,74(4):389-398
Shape memory alloy (SMA) is commercially available for a variety of actuator and damping materials. Recently, SMA wires have also become commercially available for the design of smart composite structures because SMA wires with a small diameter can be easily produced. In this work, two types of SMA-based composites are presented for investigating the vibration characteristics. First, laminated composite plates containing unidirectional fine SMA wires are fabricated. By measuring the vibration mode of a clamped cantilever, the influence of both SMA arrangement and temperature on the vibration characteristics is made clear. Next, laminated composite plates with embedded woven SMA layer are fabricated. The stiffness tuning capability is evaluated by impact vibration tests with different temperatures. It is found that the stiffness tuning capability may be improved by increasing the volume fraction of SMAs and by controlling accurately the internal stress according to the phase transformation temperature of SMAs from martensite to austenite. The theoretical prediction on the natural frequency considering the SMAs behavior and laminated structures is proposed and their results agree reasonably with experimental ones. 相似文献
13.
Yahya Bayat 《先进材料力学与结构力学》2020,27(19):1673-1686
AbstractThermal buckling and post-buckling behavior of composite beam reinforced with shape memory alloy (SMA) wires under nonuniform temperature distribution is explored. Thermo-mechanical behavior of SMA wires is formulated by using the one-dimensional Brinson SMA model. Considering von Karman strain–displacement relation, corresponding nonlinear governing equations are obtained and solved analytically. Heat conduction equation is employed and through-the-thickness temperature distribution is obtained by discretization scheme of layerwise method. Influence of SMA-wire positioning across the thickness, temperature distribution, SMA wire pre-straining level and volume fraction of SMAs upon the thermal buckling and post buckling of reinforced beam are examined and discussed in detail. 相似文献
14.
As a new kind of smart materials, shape memory polymer composites (SMPCs) are being used in large in-space deployable structures. However, the recovery force of pure SMPC laminate is very weak. In order to increase the recovery force of a SMPC laminate, an alloy film was bonded on the surface of the laminate. This paper describes the post bulking behavior of the alloy film reinforced SMPC laminate. The energy term associate with this in-plane post buckling have been given .Based on the theorems of minimum energy, a mathematical model is derived to describe the relation between the strain energy and the material and geometry parameters of the alloy film reinforced SMPC laminate. The finite element model (FEM) is also conducted to demonstrate the validity of the theoretical method. The relation between the recovery force and the material geometry parameters were also investigated. The presented analysis shows great potential in the engineering application such as deployment of space structures. 相似文献
15.
采用有限元软件ABAQUS实现了埋入形状记忆合金(SMA)丝的复合材料圆柱壳壁板结构热振动特性分析.基于“ang-Rogers本构模型编写用户子程序(UMAT)模拟形状记忆合金材料的超弹性行为和形状记忆效应,并在不同温度和应力状态下验证了程序的正确性.基于此程序,计算了埋入SMA丝的复合材料圆柱壳壁板在温度和机械载荷作用下的一阶固有频率,分析了其热振动特性和屈曲特性.模拟结果表明:加热驱动SMA丝一般会提高结构的固有频率和屈曲临界,SMA丝的数量对结构的热振动和屈曲特性有显著影响。这些结论将对智能复合材料结构设计、抗热设计有一定的指导作用。 相似文献
16.
Two innovative actuating concepts for aerospace morphing applications, based on shape memory alloys (SMAs), are proposed. The first concept investigates a composite plate incorporating embedded SMA wires. A nonlinear auto regressive with exogenous excitation model is proposed for controlling single-cycle/multi-cycle loading conditions of the SMA wires. The second actuating concept studies a novel rib configuration, which incorporates a compliant mechanism for enabling aerofoil's leading edge morphing. Different rib-compliant mechanism concepts are designed and analyzed. The most efficient rib concept is experimentally characterized. The experimental results from both actuating concepts showed good agreement with the respective numerical. 相似文献
17.
A rubber-like pseudoelastic behavior is discovered in single-crystalline face-centered-cubic (FCC) Cu nanowires in atomistic simulations. Nonexistent in bulk Cu, this phenomenon is associated primarily with a reversible crystallographic lattice reorientation driven by the high surface-stress-induced internal stresses due to high surface-to-volume ratios at the nanoscale level. The temperature-dependence of this behavior leads to a shape memory effect (SME). Under tensile loading and unloading, the nanowires exhibit recoverable strains up to over 50%, well beyond the typical recoverable strains of 5-8% for most bulk shape memory alloys (SMAs). This behavior is well-defined for wires between 1.76 and 3.39 nm in size over the temperature range of 100-900 K. 相似文献
18.
In this paper, the results of an experimental analysis on the active buckling control behaviour of a laminated composite beam with embedded shape memory alloy (SMA) wires are presented. For the purpose of enhancing the critical buckling load, active buckling control was investigated through the use of the reaction time associated with the shape recovery force of SMA wires. An increased critical buckling load and altered deflection shape due to the effects of activation of embedded SMA wires are represented qualitatively and quantitatively on the load–deflection behaviour records. The results obtained from this active buckling control test confirm that the buckling resistance in a composite beam with embedded SMA wires can be increased by the use of an activation force of the embedded SMA wires. Based on our experimental analysis, a new formula for the behaviour control of active buckling in a laminated composite beam with embedded SMA wires is also suggested. 相似文献
19.
A simulation study on the thermal buckling behavior of laminated composite shells with embedded shape memory alloy (SMA) wires 总被引:1,自引:0,他引:1
In this paper, numerical simulation analyses of the thermal buckling behavior of laminated composite shells with embedded shape memory alloy (SMA) wires were performed to investigate the effect of embedded SMA wires on the characteristics of thermal buckling. In order to simulate the thermomechanical behavior of SMA wires, the constitutive equation of the SMA wires was formulated in the form of an ABAQUS user subroutine. The computational program was verified by showing the response of the pseudoelasticity and shape memory effect (SME) at various temperatures and stress levels. Modeling of the laminated composite shells with embedded SMA wires and thermal buckling analyses were performed with the use of the ABAQUS code linked with the subroutine of the formulated SMA constitutive equations. The thermal buckling analyses of the composite shells with embedded SMA wires show that the critical buckling temperature can be increased and the thermal buckling deformation can be decreased by using the activation force of embedded SMA wire actuators. 相似文献
20.
Basic design guidelines for SMA/epoxy smart composites 总被引:4,自引:0,他引:4
The actuating ability and reliability of shape memory alloy (SMA) hybrid composites were studied in this paper. Results showed that by selecting small hysteresis SMAs such as TiNiCu alloy, SMA hybrid composites have a linear stress–temperature behavior, which is relatively easy to control. The curing process of the epoxy matrix does not affect significantly the actuating ability of the embedded TiNiCu alloy wires. A moderate prestrain of the TiNiCu wires is preferred when giving attention to both the mechanical properties and the reliability of the TiNiCu hybrid composites. Additional reinforcing fibers with a negative thermal expansion coefficient such as Kevlar fibers are helpful to strengthen the reliability of the interface and enhance the actuating ability of the SMA hybrid composites. Based on the experimental results, some basic guidelines for designing shape memory hybrid composites were proposed. 相似文献