Based On Shape Memory Polymer Composite Structures Semi-active Vibration Control

In recent years the technology of vibration control of structure has provided a new way in anti-earthquake design in buildings. The vibration control system can be categorized as active, semi-active and passive. Semi-active only expend small amount of energy to change the system's parameters such as damping and stiffness to control the structure's vibration. Semi-active system combines the advantage of active and passive one and the system is simple, stable and the maintain cost is lower.In this paper based on the basic concept of semi-active vibration control and considering the fact that stiffness of shape memory polymer can be changed reversibly with temperature, we propose a novel semi-active control system. In this system the shape memory polymer (SMP) and shape memory polymer composite (SMPC) were employed as the control element. They can be acted as the structure element in normal condition, but as the vibration on the structure occurs, the stiffness of the control element changes by changing the temperature to realize the semi-active vibration control.To understand the feasibility of the application of the shape memory polymer and shape memory polymer composite in semi-active vibration control system, the static and dynamic properties of the SMP material and the effect of the semi-active control were studied deeply. All the research work can be concluded as follows:1. The mechanics and shape memory properties of the thermal-driven SMP material were studied. Based on the experiment results, the strain-stress relationship curve, the glass transition temper??e and the relationship between the modulus and the temperature were obtained.2. The danamic damping properties of the SMP were studied with the beam vibration method and the damping factors in different temperature were obtained.3. Primary studied of the semi-active control to a SMPC composited cantilever beam were conducted to verify the feasibility of the semi-active vibration method proposed above. Under different temperatures, we test the natural frequency of the cantilever beam to obtain that temperatures can change the natural frequency of the structure. When the resonating occurs, alternate the nature frequency by heating the SMPC and the resonance was avoided. At the same time, the stiffness of the cantilever beam at different temperatures was tested in order to get the load bearing capacity of the beam in different temperatures.