Vibration Control of Hemispherical Shells with Light-Activated Shape Memory Polymers

Light-activated shape memory polymer (LaSMP) is a novel actuator with dynamic Young's modulus and strain when exposed to ultraviolet lights, which can be used in noncontact vibration control. This study focuses on the vibration control effect of LaSMP patches on hemispherical shells with free boundaries. An LaSMP strain variation model is presented with experimental verifications. Based on the strain model, the control forces of LaSMP patches on hemispherical shells are introduced. The FEM method is used to obtain natural frequencies of the free hemispherical shell by solid modeling in ANSYS and proved by comparing numerical results with analytical and experimental results. Using the modal expansion method, the LaSMP vibration control of hemispheres is investigated, and independent modal responses are presented and evaluated. The results indicate that LaSMP patch can control vibrations of hemispherical shells by reducing vibration amplitudes. And the control effect is better for low modal vibration, as the LaSMP-induced strain is relatively smaller. By establishing the relationship between LaSMP actuator forces and modal amplitude reduction, this study offers an analytical tool and procedure for future LaSMP application to vibration controls of flexible structures.