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The present investigation aims to examine the influence of geometric ratios and fibre orientation on the natural frequencies of fibre-reinforced laminated composite plates using finite element method based on Yang's theory and his collaborators. The transverse shear and rotatory inertia effects were taken into consideration in the developed Fortran computer program. It has been shown that the use of first-order displacement field provides the same accuracy as higher-order displacement field when the number of elements representing the plate structure is increased (refined mesh).However, poor precision may appear for plates with high thickness-to-side ratio h/a (thickness/side length). This discrepancy limits the application of the developed theory to thick plates (h/a<0.5). The various curves show the evolution of the dimensionless frequency (*) versus fibre orientation angle () and illustrate the apparition of a "triple-point" phenomenon engendered by the increase of the plate aspect ratio a/b (length/width) for a specific value of h/a. This point defines the maximum natural frequency and the associated fibre orientation. Also, results show that for high and/or low aspect ratios, the triple-point phenomenon does not occur. This latter is rapidly reached for thick plates than thin plates when the plate aspect ratio a/b is progressively increased.

According to ecodesign considerations and green manufacturing requirements, the choice of moulding process for the production of composite wind turbine blades must provide the existence of a common area of intersection engendered by a simultaneous interaction between quality, health, and environment aspects (i.e. Q, H, and E for abbreviations, resp.). This common area can be maximized via ecoalternatives in order to minimize negative adverse environmental and/or human health impacts. With this objective in mind, the closed-mould manufacturing RTM (resin transfer moulding) process will be the subject matter of this investigation. The reason for this choice is that RTM process participates in the reduction of VOC (volatile organic compound) emissions such as styrene vapours and presents an industrial solution to wind turbine blades production coupled with high quality finishing, good mechanical properties, lower cost, and a total absence of bonding operation of half shells. In addition to these advantages, sustainable development issues and ecodesign requirements are still, however, the main objectives to be fulfilled in this analysis with an acceptable degree of tolerance to the new regulations and ecostandards leading the way for green design of composite wind turbine blades.