Symmetric laminate with MS layer at mid plane subjected to mechanical input

The same symmetric laminate is now subjected to increasing mechanical input along with the actuator current to induce MS effect till delamination in one of the weakest interface is produced. Stress and strain at various interfaces and voltage induced in MS layer at the time of delamination in the weakest ply are shown in Figures 32.4, 32.5 and 32.6.

Figure 32.4 Stress variations at various interfaces and in MS layer at the time of delamination when the laminate is subjected to mechanical load along with actuator current

Figure 32.5 Strain variations at various interfaces and in MS layer at the time of delamination when the laminate is subjected to mechanical load along with actuator current

Figure 32.6 Open circuit voltage in MS layer when the laminate is subjected to mechanical load along with actuator current

Delamination is predicted to occur in the 1^st interface from the top due to increased stresses caused due to bending. Open circuit voltage in the sensing coil at delamination comes down to around 18 mV due to mechanical input causing bending of the beam. Bending of the beam has resulted in decrease in open circuit voltage as it works against the compressive stresses in MS layer and thus reduces its sensing capability. The kind of bending (for example: sagging or hogging) decides the open circuit voltage sensed in the sensing coil.