Microscopic control actions of LaSMP actuators on hemispherical shells

Abstract

Light activated shape memory polymer (LaSMP) is one of novel shape memory polymers with dynamic strain and Young’s modulus when exposed to UV lights. This study investigates distributed microscopic control actions of LaSMP patches on hemispherical shells with free boundary. Based on strain models established in the experiments, governing equations of the spherical shell are defined and control forces in the meridional, circumferential and transverse directions are derived respectively. In case studies of LaSMP patch laminated on the shell by covering specific wavelength at each mode in the circumferential direction, the meridional and circumferential forces turn to zero. Then, the dominant transverse control forces and its components resulting from the bending moments and membrane forces are compared at different modes. Parametric analyses are carried out to evaluate the microscopic actuation effects of actuator position, thickness and shell radius, LaSMP thickness, etc. LaSMP induced meridional and circumferential microscopic membrane/bending control actions on hemispherical shells are evaluated. The analyses indicate that the transverse control forces increase with increasing of LaSMP patch thickness and decreasing of hemispherical shell thickness and radius. Then, the normalized control forces are derived by dividing LaSMP patch size. The parametric analyses confirm that the normalized control forces caused by membrane forces dominate the control effect and the best control position is near the boundary of hemispherical shell. This work provides an analysis procedure on estimating LaSMP vibration control actions and gives theoretical predictions for idealized LaSMP vibration control of hemispherical shells.