SMAs复合材料层板大变形分析计算

在复合材料层板结构中铺设形状记忆合金丝,利用形状记忆合金弹性模量随相变状态的不同变化,受限回复时可以产生很大的回复力的特点,除改善和增强复合材料层板本身性能外,还能使复合材料层板产生弯曲,扭转等形状变化。如何正确有效地计算其力学特性,是复合材料层板形状控制以及设计和应用形状记忆合金复合材料智能结构的基础。本文在复合材料层板的有限元分析中考虑形状记忆合金丝的热力学特性以及大变形回复的影响,并通过实验进行分析和对比,得到一些有意义的结论。      

埋入形状记忆合金丝的复合材料圆柱壳壁板的热振动特性分析

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。     

含分层复合材料层板的压缩性能

使用商用有限元软件建立了含分层复合材料层板的有限元模型,采用Hashin失效准则对层板内单元进行损伤判断,并编写程序对失效单元进行刚度折减,使用cohesive单元模拟层间区域,并对缺陷区域进行弱化处理,利用应力失效判据和能量释放准则判断层板内起始分层与分层的扩展。对完好以及含分层缺陷复合材料单向层板试验件进行压缩实验研究,实验结果给出了分层位置和尺寸及对材料压缩性能的影响。研究表明,有限元模拟结果与实验结果具有良好的一致性。     

纤维增强复合材料层板高速冲击损伤数值模拟

推导了复合材料应变率相关三维本构关系, 并将其用于复合材料层板高速冲击损伤的数值模拟。该模型在复合材料层间引入界面单元模拟层间分层, 结合三维Hashin失效准则进行单层板面内损伤识别, 引入材料刚度退化, 采用非线性有限元方法, 研究了复合材料层板高速冲击的破坏过程及层板的损伤特性。数值分析结果表明, 剩余速度预报结果与实验结果吻合较好, 层板的主要损伤形式是层间分层、 基体微裂纹和纤维断裂, 减小弹体直径、 增大铺层角度和层板厚度能够有效降低层板损伤面积。      

带有铝板复合材料层板固化过程中残余应力演化

本文对两种材料组成的层板的残余应力进行了研究.提出应用有效温差并结合线膨胀系数对带有铝板复合材料层板固化成型过程中残余应力形成进行理论分析,其中残余应力主要考虑温度产生的.采用先进的光纤技术对带有铝板复合材料层板固化成型过程中残余应力进行试验研究,即将光纤布拉格光栅(FBG)分别埋入到复合材料内部及复合材料与铝板之间,监测固化全过程残余应变的演变,并且构件最终变形与理论分析释放残余应力方向一致.     

面内损伤对埋藏分层影响的三维有限元分析

运用大型有限元软件ANSYS,基于复合材料层合板损伤理论,建立了含面内损伤和埋藏分层的复合材料层板三维有限元模型.分析了面内损伤对复合材料层板分层的影响.采用三维Hashin准则预测复合材料损伤,分层区损伤采用多种损伤模型,损伤发生后,认为材料仍连续,并修改损伤单元对应的材料参数.通过虚拟裂纹闭合技术（VCCT）计算分...     

形状记忆合金混杂复合材料弯曲变形的设计

为了预报形状记忆合金混杂复合材料的物理性能与弯曲变形能力,提出了兼顾常规力学性能和主动变形能力的系统的设计方法.以形状记忆合金体积含量为主要设计变量,分析了丝状、带状及板状形状记忆合金埋入复合材料层合板后,这种混杂复合材料力学性能的变化.经过某种特殊加工的板状NiTi合金,不但增大了NiTi合金的体积含量,还增大了形状记忆合金电阻值,以此来提高NiTi合金的响应速度.采用有限元方法进行设计计算及分析,验证了该设计方法的正确性.     

玻璃纤维单丝拔出实验及其有限元模拟

在细观有限元模型基础上,利用ANSYS有限元程序对不同埋入长度的玻璃纤维/水泥复合材料的纤维拔出行为进行了数值模拟,结合玻璃纤维/水泥复合材料的纤维拔出实验数据验证数值模拟的合理性,并讨论接枝对复合材料拔出行为的影响.结果表明,环氧树脂接枝对复合材料的界面平均剪切强度、破坏模式均有较大影响,与无接枝情况相比,两种接枝中环氧树脂接枝的复合材料界面的平均剪切强度提高了92％;破坏模式与接枝有关,界面破坏导致无接枝玻璃纤维拔出,水泥破坏导致环氧树脂接枝玻璃纤维拔出.此外,还通过有限元分析结果讨论了破坏模式特征及其演化规律,研究结果有助于分析该类复合材料的破坏机理.     

含紧固穿透分层复合材料层板的疲劳扩展

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。     

形状记忆合金的力学及界面参数和体积分数对大块金属玻璃基复合材料增韧的影响

采用考虑塑性的超弹性材料模型和基于损伤塑性的准脆性材料模型,建立了三维单胞有限元模型,模拟了形状记忆合金颗粒增韧大块金属玻璃基复合材料的单调拉伸行为。讨论了形状记忆合金的力学参数、体积分数、界面厚度和界面材料参数对金属玻璃增韧效果的影响。结果表明:提高形状记忆合金的相变应变和马氏体塑性屈服应力将显著提高形状记忆合金颗粒增韧大块金属玻璃基复合材料的拉伸失效应变;形状记忆合金弹性模量超过50.0GPa、马氏体塑性屈服应力超过1.8GPa后,复合材料的拉伸失效应变变化不大。能同时兼顾失效应变和失效应力的形状记忆合金体积分数为15%左右。复合材料界面弹性模量和界面屈服应力的增加将提高复合材料的失效应力,但对失效应变影响不大;复合材料界面厚度的增加在提高失效应变的同时,也降低了复合材料的失效应力。     

Effects of shape memory alloys on low velocity impact characteristics of composite plate

The effects of shape memory alloy thin films embedded in composite plates for improving damage resistance of composite structures under low velocity impact were investigated numerically. Analysis model for SMA thin film was developed based on Lagoudas’ model and implemented using the user defined material subroutine of the ABAQUS/Explicit finite element program. Composite damage model based on the Chang–Chang failure criteria was also implemented to consider progressive damage behavior. The finite element simulation of low velocity impact behavior of a shape memory alloy hybrid composite plate was performed using the ABAQUS/Explicit program. Parametric studies were performed to investigate the effect of shape memory alloys for improving damage resistance of composite plate.     

Nonlinear free vibration analysis of shape memory alloy embedded laminated composite shell panel

High specific strength and stiffness are characteristics desired for aircraft and launch vehicle domains to enhance the payload gain and performance. The mechanical properties of the composites can be further tailored by embedding structural components, such as shape memory alloys, into the passive composite structure. The present study is primarily focused on the nonlinear free vibration analysis of spherical and cylindrical composite shell panels embedded with shape memory alloy fibers. The nonlinear finite element governing equations based on the higher-order shear deformation plate theory and principle of virtual work with nonlinear von-Karman strain displacement relations are employed for the analysis. The temperature-dependent material properties of shape memory alloy are considered in the formulation. A nine-noded isoperimetric element is accounted for synthesizing the element for the finite formulation. The Young's modulus and the recovery stress vary with temperature and higher nonlinearity. The incremental method is used to generate the inputs for the temperature-dependent nonlinear properties of materials. The temperature change is divided by many small temperature increments. The temperature-dependent material properties are assumed constant during the small increment. The mechanics of shape memory alloy in substrate are presented and the governing equation of laminated composite with shape memory alloy is obtained and implemented in the MATLAB 7.8 program.     

SMA杂交复合材料板低速冲击响应研究

本应用有限单元法，研究了形状记忆合金(SMA)对复合材料板低速冲击响应性能的影响。研究中，通过分析对比不同SMA体积含量复合材料板的低速冲击响应，得出SMA能的效地改善复合材料板低速冲击响应性能的结论，其中，SMA体积含量为0．3的复合材料板的最大挠度大约减少了30％。     

Dynamic instability response of smart composite material

Laminated composite is common to replace traditional metals in today's industries due to its high specific strength. Shape memory alloy has been used to improve structural behaviours such as buckling, vibration and fatigue through its well‐ known property of shape memory effect. This ability of shape memory alloy to improve the parametric instability behaviour of laminated composite plate has not been studied in the past and as such, this study is conducted. Here, shape memory alloy wires are embedded within the outer layers of the laminated composite plates. The Mathieu‐Hill equation for the parametric instability of the shape memory alloy composite plate has been developed using finite element method based on the first order shear deformation theory. The formulation is validated and parametric studies have been conducted to investigate the effect of shape memory alloy on the dynamic instability behaviour of the composite that corresponds to factors such as static load factor, thickness of the plate and boundary conditions. The study shows that shape memory alloy improves significantly the dynamic instability behaviour of the laminated composite plate by shifting the instability chart to the right. The effect of shape memory alloy can increase the frequency centre of the instability chart by more than 100 %.     

基于齿轮机构的SMA-摩擦阻尼器试验研究及数值模拟EI北大核心CSCD

基于齿轮机构对形状记忆合金(SMA)丝非比例拉伸的特点,提出了一种新型SMA-摩擦阻尼器,并阐述了该阻尼器的基本构造和工作原理。对SMA丝进行循环拉伸试验,考察了加载幅值、加载速率对其力学性能的影响规律;分别对齿轮摩擦单元和SMA-摩擦阻尼器试件进行了低周往复荷载下的力学性能试验,得到了摩擦材料、预紧力以及位移幅值对单次循环耗能、割线刚度、等效阻尼比和自复位率等力学性能指标的影响规律;建立了SMA-摩擦阻尼器的简化力学模型并进行了数值模拟。研究结果表明:所用复合树脂材料较黄铜材料出力更大,性能更稳定;新型阻尼器具有良好的耗能能力、承载能力及自复位能力,可实现大行程设计;利用OpenSees有限元模型计算得到的滞回曲线与试验曲线吻合较好,验证了力学模型和材料本构二次开发的正确性。     

TiNiNb形状记忆合金丝精密脉冲电阻对焊工艺分析

使用自行研制的UMN -3型精密脉冲电阻对焊机对TiNiNb形状记忆合金丝的焊接性进行了研究 ,分析了焊接电流、焊接压力、顶锻压力和保护气体等焊接参数对焊接接头微观组织和力学性能的影响规律 ,并给出某些TiNiNb形状记忆合金丝获得优质接头的工艺条件 .研究结果表明 ,所研制的精密脉冲电阻对焊机可实现TiNiNb形状记忆合金丝的优质连接 ,这对于进一步研究、开发TiNi基形状记忆合金丝的潜能 ,具有重要的理论和实际应用价值 .     

高导热石墨烯-碳纤维混杂增强热致形状记忆复合材料研究进展及发展趋势

热致形状记忆复合材料(SMPC)是一种能够对外界温度刺激做出响应的智能材料,与传统热致SMPC相比,高导热石墨烯(GR)-碳纤维(CF)混杂增强热致SMPC具有形状记忆性能优良、比强度高和导热性强等一系列优异性能,近年来受到人们广泛的关注并开展了相关研究。本文从形状记忆材料相关历史起源与应用入手,聚焦GR-CF混杂增强热致SMPC研究前沿问题,分别对该复合材料浸渗规律、成型工艺、形状记忆性能强化规律和弯曲失效规律四个方面的国内外研究现状进行了文献综述,并结合现有研究情况对其中出现的难题进行了探讨,最后指出了该热致SMPC未来有待深入研究的方向。      

Applications of titanium-nickel shape memory alloys

The shape memory alloy based on the TiNi phase has given rise to a wide range of commercially viable products. Two applications are described which illustrate the different ways in which shape memory can be used in an industrial product. In one of these, the change in shape is prevented so that the shape memory tubular element can be used as a mechanical coupling to join two pipes together securely. Such couplings have replaced welding in hydraulic lines in aircraft and ships and in the repair of undersea pipe lines.The other application demonstrates the use of a tubular shape memory element in torsion to operate a boom latch and release mechanism for the deployment of the booms on a space satellite. It is shown that a shape memory alloy can satisfy a tight and exacting specification in operating as an actuator.     

Thermal post-buckling and flutter characteristics of composite plates embedded with shape memory alloy fibers

It is investigated that the composite plate embedded with shape memory alloy (SMA) fibers is subject to the aerodynamic and thermal loading in the supersonic region. The nonlinear finite element equations based on the first-order shear deformation plate theory (FSDT) are formulated for the laminated composite plate embedded with SMA fibers (SMA composite plate). The von Karman strain–displacement relation is used to account for the large deflection. The incremental method considering the influence of the initial deflections and initial stresses is adopted for the temperature-dependent material properties of SMA fibers and composite matrix. The first-order piston theory is used for modeling aerodynamic loads. This study shows the effect of the SMA on the critical temperature, thermal post-buckling deflection, natural frequency and critical dynamic pressure of the SMA composite plate.