Drive point moment mobility of anisotropic plates

The drive point moment mobility of an infinite plate is an important function that can be used for predicting vibratory responses when the excitation takes the form of a bending moment. For many engineering applications plate-like structures are constructed from fibre reinforced composites to utilize high strength to weight and stiffness to weight ratios. The directional nature of fibre reinforced composites frequently results in structural anisotropy and the mathematical description of such systems is more complicated than their isotropic metallic counterparts. In this study anisotropic plates excited by rotational bending moments are investigated. Expressions are derived for the drive point moment mobility of thin anisotropic plates having monoclinic and orthotropic symmetry. One important application is that such expressions can be used directly to calculate the frequency averaged power absorbed by a plate due to a harmonic bending moment. The variation of the moment mobility with fibre orientation is also investigated since it is often the case that composites are tailored by varying the direction of the fibres. It is seen that at the lowest frequencies the orientation has little effect on the stiffness and resistance part of the mobility but as frequency increases the effect becomes significantly more pronounced. The study also examines the effects of static in-plane forces on the mobility when plates are pre-tensioned.