Environmental Effects on Unsymmetric Composite Laminates

Abstract

In order to take full advantage of the tailorability of composite materials, the response of unsymmetric composite laminates is studied in an integrated analytical/ex perimental program. The laminates tested include a symmetric and an unsymmetric layup, [0 2/452] s and [04/454] I , constructed of the IM7/977-2 graphite epoxy material system pro duced by Fiberite. The test conditions simulated mclude both ambient and hot/wet condi tions in addition to tension and torsion. A quasi three-dimensional finite element program is used to evaluate the stress-strain response of these laminates. These responses are com pared with experimental observations.

Review of Composite Marine Risers for Deep-Water Applications: Design, Development and Mechanics

“…In the research by Venkatesan et al [252], carbonfibre-reinforced polymer (CFRP) composites were observed to have long-term qualities after being exposed to clean water and sea water at the same time, with noteworthy differences under various temperatures. Many researchers also concur with the finding that the CFRP's long-term tensile strength is lowered to between 80% and 95% of its original value in the short term [252][253][254][255][256][257][258]. It was also discovered in another study by Bismarck et al [58] on the evaluation of the carbon/PEEK thermoplastic composite that although its axial tensile strength was unaffected by boiling water, its transverse tensile strength was affected.…”

Comparative Study of Vortex-Induced Vibration of FRP Composite Risers with Large Length to Diameter Ratio Under Different Environmental Situations

“…Venkatesan et al [6] found that none of the long-term properties of carbon fiber reinforced polymer (CFRP) composites experienced any significant variations after exposure to pure water and seawater at different temperatures. On the other hand, many researchers [3,4,8,9] found that the long-term tensile strength of a CFRP reduced to about 80-95% of its short-term values. For thermoplastic composite carbon/polyether ether ketone (PEEK), the transverse strength decreased obviously in boiling water [10] and therefore, the maximum service temperature of thermoplastic FRP composites has to be well below the glass transition temperatures of their polymer matrices.…”

Theory for Midplane Asymmetric Sandwich Cylindrical Shells

“…Numerous researchers have investigated the effects of asymmetric construction on composite structures. Of these, most have focused on developing analytical, numerical, or experimental methods to assess the impact asymmetry has on the structural response of monocoque (i.e., solid) laminated beams or plates (e.g., [1][2][3][4][5]). Others have used similar methods to examine the impact of asymmetry (both in the skins themselves and as a whole sandwich) on sandwich beams or plates (e.g., [6][7][8][9]).…”