Composite preforming defects: a review and a classification

Abstract

Advancing in the process of extending the use of composites for structural parts applications, it is inevitable to work on complex shapes. That is the main reason why understanding the complex forming mechanisms and the factors put into play during the process of composite materials is a major interest for both pre-impregnated forming and dry fabric preforming. Thus, the apdpearance of defects is a major concern and predicting their appearance for optimal product quality is the priority. A great number of authors showed that defects degrade the overall performance of the composite by creating local heterogeneities. Many factors can initiate these defects. This article is an assembly of the development of the literature on this subject. It is an attempt to provide a description for each defect and a classification order following the scale, the behavior mechanisms, the appearance plan. This will help to converge toward an identification of the defects manifesting during the composite forming.

Taxonomy of Damage Patterns in Composite Materials, Measuring Signals, and Methods for Automated Damage Diagnostics

“…For monolayer composites, the fabric deforms in and out of the plane, taking the shape of a waved curve that can vary in length, number, and magnitude; such defects are known as wrinkles. For multilayer materials, different radii between the inner layers and the outer layers at the corner result in an inner layer buckling to cope with the compressive force [43]. This gives rise to another pattern of wrinkles that are seen in multilayer materials.…”

Surrogate model of the thermoforming of fiber reinforced thermoplastics

“…The draping behaviour is mainly determined by the in-plane shear property of the organo sheet. Furthermore, the different deformation modes transverse compression, out-of-plane bending and in-plane tension are important variables which influence the formability of the material and thus the forming result [2]. Accordingly, multiple defects such as wrinkling or fiber fracture can occur due to excessive shear stresses or tensile stresses [2].…”

“…Furthermore, the different deformation modes transverse compression, out-of-plane bending and in-plane tension are important variables which influence the formability of the material and thus the forming result [2]. Accordingly, multiple defects such as wrinkling or fiber fracture can occur due to excessive shear stresses or tensile stresses [2]. The defects are mainly reduced by the selection of suitable process parameters, which increases the component quality.…”

Modelling and Simulation Strategies for Fluid–Structure-Interactions of Highly Viscous Thermoplastic Melt and Single Fibres—A Numerical Study

“…However, handling and manufacturing of TPC typically result in process-induced fibre reorientation phenomena. Particularly joining or forming processes often involve large deformations which are accompanied by local fibre rearrangements such as wrinkles and discontinuities [ 7 ] or fibre reorientation and fibre fractures in the joining area [ 8 , 9 , 10 , 11 , 12 ]. Process-induced fibre reorientations are well investigated for short fibre applications, where injection moulding is used and a method for manipulation under magnetic fields is already available [ 13 , 14 ].…”