Dynamic analysis of a simply supported beam with LaSMP patches

Light-activated shape memory polymer (LaSMP) is a novel smart material, whose stiffness can be tuned by irradiating with UV light. By changing the Young's modulus of LaSMP patches, the natural frequency of a simply supported beam laminated with LaSMP patches can be actively affected and the dynamic response of the beam can be influenced. Based on the stepped beam theory, dynamic equations were established for a simply supported beam laminated with LaSMP patches. The effect of LaSMP patch properties on the frequency variation of the first three modes was analyzed. It was found that the frequency variation range increases with increasing length. The strategy of locating the LaSMP patch pair on a single location was discussed first, and it was observed that when the LaSMP patch pair was located at antinodes of each mode, the widest frequency control range can be obtained. When multiple LaSMP patch pairs were considered, analytical results showed that the natural frequency ranges were 24.97% and 52.47% higher than by concentrating the patches on a single location for the second and third mode, respectively. When the controllable natural frequency range increases, the control capability of the LaSMP patch on the dynamic response of the beam structure increases as well. As a result, multiple LaSMP patches would have better potential for vibration control than single patches.