An experimental characterization of wrinkling generated during prepreg autoclave manufacturing using caul plates

Abstract

Out-of-plane ply wrinkling is a major quality issue for carbon fiber reinforced prepreg parts. Its triggers are numerous and not every influencing parameter is fully understood, yet. The research presented in this paper aims at providing a better insight into ply wrinkling generated during autoclave compaction using caul plates. A detailed description of the experimental set-up and the applied methodology is provided. Statistical analyses of varying influencing factors such as part thickness, geometry, tool–part interaction, and laminate lay-up are presented. This, in turn, generates a better understanding of their impact on fiber wrinkling risk and size. Part geometry and compaction deformation show the most significant influence on wrinkle size. However, for the given manufacturing concept, tool–part interaction also plays a significant role. It influences both the dimension and location of the wrinkles, as well as the existence and size of a critical flange length of the part. A noteworthy effect on wrinkle generation and size can also be observed when adding unidirectional plies to an otherwise fabric laminate.

Consolidation-driven wrinkling in carbon/epoxy woven fabric prepregs: An experimental and numerical study

“…16 and 17, indicating bending-induced compression (either due to bending of the plies in hand-layup or during debulk. The instability caused by compressive forces on the tows is typically accompanied by a combination of in-plane fibre waviness, and out-of-plane wrinkling [12].…”

“…This includes defects such as porosity [6,7], residual stresses [8], and dimensional changes [9]. Additionally, there exists a class of fibre-path defects such as out-of-plane wrinkling and in-plane waviness, which is very much dependent on the manufacturing process, frequently observed in the autoclave moulding process of thick composite parts [10][11][12][13][14]. The global and local process-induced defects arising from the soft and compliant nature of the curing thermosetting resin below the gelation point may have a significant impact on the structural performance which underlines the importance of the consolidation phase in the CFRP product development process [15,16].…”

“…However, if the plies are not able to slip over each other, wrinkles form either in-plane or out-of-plane, as shown in Fig. 1, and manifests itself as "missing length" at the ply terminations [12].…”

“…A number of studies have aimed to identify the key influencing parameters responsible for the formation of fibre-path defects in prepreg applications [10,12]. Aside from the final part geometry, ply sequence, and intra-ply properties, it has been shown that the formation of wrinkling and in-plane waviness is mostly affected by inter-ply shear properties and compaction behaviour of the plies.…”

A New Vacuum Pressure Infiltration CFRP Method and Preparation Experimental Study of Composite

“…The AM process is suitable for preparing large components. It has the advantages of a stable preparation process and low porosity of the product [10], but it requires high equipment costs and large energy Each of the above mentioned preparation process methods has advantages and disadvantages. The promotion and application of composite materials need low cost, high efficiency, good process stability, and adaptive preparation methods as support.…”