Experimental and computed natural frequencies of square pultruded GRP plates: effects of anisotropy, hole size ratio and edge support conditions

Experiments have been carried out to determine the free vibration frequenci es and mode shapes of 3.2 mm thick, pultruded GRP, square plates with six c ombinations of clamped (C), simply supported (S) and free (F) edge supports . Comparison of experimental and theoretical/numerical frequencies confirms that thin homogeneous orthotropic/anisotropic plate theory provides a reas onable model for predicting the free vibration response of pultruded GRP pl ates. Additional vibration experiments were carried out on plates with cent ral circular cutouts. The hole size ratios were varied from about 0.1 to 0. 4 for three combinations of clamped (C) and simply supported (S) edge condi tions. Finite-element (FE) frequency and mode shape predictions based on or thotropic plate theory were again shown to be in reasonable agreement with the experimental frequencies and modes. (C) 2000 Elsevier Science Ltd. All rights reserved.