Experimental identification of process parameters inducing warpage of autoclave-processed CFRP parts

Manufacturing distortions of a CFRP box-structure – A semi-numerical prediction approach

“…In the following this configuration is denoted as I. The second configuration considers for those effects, whereas parameter modification is done based on engineering judgment and supported by former warpage investigations presented in [4,7]. Fig.…”

“…The main aim is to characterize the acting effects that are responsible for the curvature of the flat base area of the box structure. As outlined in [3][4][5][6], multiple sources for the occurring deformations are conceivable such as a gradient in V f , an inhomogeneous curing front propagation, tool-part interaction or forced-interaction. As no curvature of the flange areas is obtained in the measurements, it is assumed that the curvature of the box is induced in the base-surface area.…”

“…Stefaniak et al [4] experimentally verify a significant dependency of the warpage deformations of thin flat composite specimens from tool-surface roughness and the prepreg material itself. Radford [5] shows that a single-sided mold concept can result in fiber volume fraction (V f ) gradients in laminate thickness direction.…”

Prepreg processing of advanced fibre-reinforced polymer (FRP) composites

“…Since the reinforcement fibres do not chemically react, and often have a much smaller coefficient of thermal expansion than the cured matrix, this can lead to substantial geometrical distortions of the cured part, often called spring-back (Ersoy et al, 2010;Stefaniak et al, 2012). From the illustration in Fig.…”

A thermo-viscoelastic model of process-induced residual stresses in composite structures with considering thermal dependence

“…Some fundamental properties of matrices are investigated recently with experimental and analytical methods taking into account coefficients of thermal expansions (CTEs), cure behaviours and stresses relaxation of materials [27][28][29][30][31][32]. Consequently the thermo-viscoelastic models of process-induced residual stresses in composite structures have been developed.…”