Numerical modeling of interply adhesion in composite forming of viscous discontinuous thermoplastic prepregs

Mulye, Paris Dilip; Hemmer, Julie; Morançay, Lionel; Binétruy, Christophe; Leygue, Adrien; Comas-Cardona, Sébastien; Pichon, Pierre; Guillon, Damien

doi:10.1016/j.compositesb.2020.107953

Cited by 10 publications

(18 citation statements)

References 38 publications

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“…Recently, the tensile stress was lowered in an update on AniForm based on advancing insight. Lastly, Mulye et al [9] found an average tensile stress of 6.2 kPa in their research on a thermoplastic composite with a PA-66 matrix.…”

Section: Discussionmentioning

confidence: 94%

“…The study of Mulye et al [9] seems to be the only one that dealt with characterizing the ply-ply adhesion of TPCs in melt. These authors used a DMA with only the molten matrix material to measure the polymer melt strength as function of the debonding rate, which was subsequently used in a forming simulation for a fiber-reinforced PA-66 part to improve the prediction of local discontinuous plies (patches).…”

Section: Introductionmentioning

confidence: 99%

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Experimental setup and method for the characterization of ply-ply adhesion for fiber-reinforced thermoplastics in melt

PIERIK

2023

Materials Research Proceedings

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Abstract. Process simulation software for hot press forming is a vital tool for the development of complex continuous fiber-reinforced thermoplastic parts for structural applications. The simulation tools need to be accurate to truly facilitate the design stage, which in turn requires accurate material characterizations and constitutive models. The material forming behavior is composed of different deformation mechanisms, one of which is the separation of adjacent plies or delamination. Currently, the resistance against delamination or ply-ply adhesion is modeled as a constant tensile stress that needs to be overcome, the value of which is based on an educated guess. To date, no standard exists to characterize this material property for thermoplastic matrix composites (TPC) in melt. Hence, we discuss and evaluate several methods to measure ply-ply adhesion of TPCs. The most promising approach, a so-called probe test, was further pursued and a setup was designed and manufactured for the use in a rheometer. Subsequently, we measured the required normal force to separate two C/LM-PAEK tapes in melt. Repeated tests on the same specimen resulted in an increasing adhesive peak force, which we relate to a change in the amount and distribution of the matrix material at the ply’s surface. The peak force increased also with increasing compression time and pressure. We found a reasonable correlation of the average measured peak force with the values currently assumed in simulation software.

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Section: Discussionmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Experimental setup and method for the characterization of ply-ply adhesion for fiber-reinforced thermoplastics in melt

PIERIK

2023

Materials Research Proceedings

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“…This work presents such a shell-based unified modeling approach that combines a novel pinching shell element, elastoplastic constitutive model for pinching shell and the interply adhesion model (Mulye et al, 2020) in order to provide a unified solution to model both forming and consolidation-flow. This unique unified approach of simulating forming and consolidation provides a set of additional outputs such as the through-thickness stress, the final deformed shape of the plies including the squeeze flow effect and the changes in the orientation of fibres within the plies during and after the process.…”

Section: Figurementioning

confidence: 99%

“…This two-step approach was tested on an industrial model and the practical challenges that were observed were as follows [discussed in more detail in (Mulye, 2021)]:…”

mentioning

confidence: 99%

Unified numerical process modeling of forming and consolidation for thermoplastic composites with prepreg patches

et al. 2023

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The main idea behind “Quilted Stratum Process” (QSP®) is to create a flat blank made of unidirectional/woven thermoplastic prepreg patches instead of using uniformly shaped prepreg stack as is the case with standard thermostamping process. Thus, using QSP®; one can manufacture components with complex geometries by using nearly rectangular patches while still maintaining a short cycle time similar to the standard thermostamping process. The use of near-rectangular patches results in a significant material saving which is a necessity for a sustainable product development. During standard thermostamping and/or QSP®; the consolidation phase plays a key role in the strength and quality of the final product. This becomes even more important in the case of unidirectional thermoplastic prepregs where mechanisms such as transverse squeeze flow can impact not only the in-plane dimensions of the prepreg but also the fibre orientations within the prepreg. This work presents a unified modeling approach that combines a novel pinching shell element, a new elasto-plastic constitutive model for pinching shell in order to provide a unified solution to simulate both forming and consolidation-flow using a shell-based approach. This unique unified approach of simulating forming and consolidation provides a set of additional outputs such as the through-thickness stress, final deformed shape of the plies including the squeeze flow effect and the changes in the orientation of fibres within the plies during and after the process. This work finally demonstrates how this information can help the manufacturers to design better tooling based on the outcomes of the numerical process simulation in order to achieve a desired product quality. Additionally, one can also steer the final fibre orientation which results from the initial position of the patch, its forming and squeeze flow.

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“…In this manufacturing route, composite laminates are consolidated at very low pressures (<1 bar). Even if a good consolidation quality can be obtained by this process (Saffar et al, 2020), the influence of a reduced pressure on the interlaminar consolidation phenomena (intimate contact (Loos and Dara, 1987;WooLee and Springer, 1987;Cassidy and Monaghan, 1994;Butler et al, 1998;Yang and Pitchumani, 2001;Khan et al, 2010;Levy et al, 2013;Schaefer et al, 2017;Çelik et al, 2020), autohesion or healing (WooLee and Springer, 1987), (De Gennes and Georges, 1981;Mantell and Springer, 1992;Lamèthe et al, 2005;Régnier et al, 2005;Mulye et al, 2020), melt flow (Barnes and Cogswell, 1989;Groves and Stocks, 1991;Stanley and Mallon, 2006;Picher-Martel et al, 2017), crystallisation (Ijaz et al, 2007, (Guan and Pitchumani, 2004a;Guan and Pitchumani, 2004b;Tierney and Gillespie, 2004;Dörr et al, 2019;Martineau et al, 2019)) is still not fully understood.…”

Section: Introductionmentioning

confidence: 99%

Influence of prepreg parameters on the interlaminar consolidation of fiber reinforced thermoplastic laminates manufactured by vacuum-bag-only process

et al. 2022

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To better understand the influence of the prepreg parameters such as surface roughness, fibres/matrix distribution (e.g. presence or absence of pure matrix layer on the prepreg surface) and initial matrix crystallinity, two different carbon fibres/Poly-Ether-Ketone-Ketone prepregs are used to fabricate unidirectional laminate by Vacuum-Bag-Only (VBO) process. By an in-situ monitoring set-up, the laminate thickness and the temperature difference along the thickness direction are measured throughout the consolidation cycle. The quality of laminate is assessed in terms of interlaminar shear strength and void content. A finite element model has been developed to describe the intimate contact establishment by the deformation of surface roughness between the glass transition temperature and the melting temperature of the matrix. In particular, the model takes into account the real profilometer data and the variable Young’s modulus of matrix in terms of temperature and crystallinity. Finally, the high influence of the matrix crystallinity degree and the surface roughness on the intimate contact phenomenon is highlighted.

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Numerical modeling of interply adhesion in composite forming of viscous discontinuous thermoplastic prepregs

Cited by 10 publications

References 38 publications

Experimental setup and method for the characterization of ply-ply adhesion for fiber-reinforced thermoplastics in melt

Experimental setup and method for the characterization of ply-ply adhesion for fiber-reinforced thermoplastics in melt

Unified numerical process modeling of forming and consolidation for thermoplastic composites with prepreg patches

Influence of prepreg parameters on the interlaminar consolidation of fiber reinforced thermoplastic laminates manufactured by vacuum-bag-only process

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