Analysis of Magnetostrictive Composites

Here a laminated composite beam has been considered with one of its layer having Terfenol-D particles as shown in Figure 30.1.

Figure 30.1 Smart composite beam with delamination

In such a laminate, the Terfenol-D layer will experience a change in stress at the onset of delamination as the particular layer will not be taking any load leading to transfer of stresses to other layers including the MS layer. This change of stress in MS layer brings a change in its magnetic state which can be sensed as an induced open circuit voltage in sensing coil enclosing the beam. The Terfenol-D composite carries an initial or bias mechanical stress and magnetic field intensity. A current of the form

(30.3)

is applied along with appropriate bias field through the actuator coil resulting in stresses in the magnetostrictive layer at a localized portion only over a width equal to the width of the coil. Here I_b is the bias current, I₀ the amplitude and ω the frequency of the applied current.