SMA智能梁结构振动控制试验研究

Test investigation on vibration control of intelligent beam with shape memory alloy

形状记忆合金(SMA)材料凭借其弹性模量大幅度温变特性被成功应用于智能梁结构变刚度振动控制。根据变刚度控制原理,制定合理的控制策略,成功降低了系统的稳态和瞬态振动响应。试验发现:所采用的Ti50Ni41Cu9三元记忆合金具有较高的热响应速率,在温度控制下相变前后弹性模量能够发生4倍以上变化;将记忆合金板安装于组合梁根部,能够显著调节结构的前3阶固有频率;通过对记忆合金进行变温操作,有效降低了系统共振状态的响应,并研究了变刚度速率对系统非线性特征和控制效果的影响;通过制定温度加载策略,成功实现了宽频段变频激励下智能梁瞬态振动响应的控制。研究结果表明,对记忆合金进行温度控制可以有效改变结构的固有频率并影响振动特性,跨越共振区时进行变刚度操作所导致的非线性特征能够有效分散主频振动能量,较快的刚度变化速率有助于振动响应的进一步降低。

Shape memory alloy （SMA） has been successfully applied to variable stiffness vibration control of intelligent beam based on the characteristics of elastic modulus changing with temperature significantly. The steady and transient response is restrained using a correct control strategy according to the variable stiffness control theory. The data obtained have demonstrated that Ti50 Ni41Cu9 shape memory alloy has much higher rate of thermal response, and the elastic modulus changed sharply under temperature control up to four times; the first three-order natural frequencies could be regulated significantly when the SMA is fixed at the root of the beam; the resonant response is attenuated by changing the temperature of SMA, and the influence of stiffness varying rate on the nonlinear characteristics and control effect is analyzed; by developing a temperature loading method, the wide-band transient vibration response is controlled in the process of exciting force variation. The results show that the natural frequencies of the beam can be changed effectively by variable stiffness control over the SMA, and the vibration performance will be affected. Nonlinear characteristics generating in the process of stiffness varying through the resonance frequency can disperse vibration energy of the main frequency, and the faster variation rate contributes to restraining the vibration response more effectively.