Effect of compaction roller on layup quality and defects formation in automated fiber placement

Bakhshi, Nima; Hojjati, Mehdi

doi:10.1177/0731684419868845

Cited by 41 publications

(22 citation statements)

References 14 publications

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“…The compression force applied and controlled by the roller plays a vital role in the mechanical properties of tack and wrinkle formation. The compaction pressure distribution generated by roller on prepreg was investigated in [19,20], respectively. Besides, the compression force between the roller and tape and the guidance system leads to an initial defect in tape that affects the wrinkle formation.…”

Section: Methodsmentioning

confidence: 99%

Wrinkle Formation and Initial Defect Sensitivity of Steered Tow in Automated Fiber Placement

Kheradpisheh

Hojjati

2021

J. Compos. Sci.

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This paper aims to study the wrinkle formation of a prepreg with initial defect during steering in automated fiber placement (AFP). Wrinkle formation has a detrimental effect on the mechanical properties of the final product, limiting the AFP applications. A theoretical model for wrinkle formation has been developed in which a Pasternak foundation and a Koiter imperfection model are adapted to model viscoelastic characteristics of the prepreg tack and initial defect of the prepreg, respectively. The initial defect is defined as a slight deviation of the tow’s mid-plane from a horizontal shape. The initial defect is generated in the tow by moving the tow through the guidance system, pressure of the roller, and resin tackiness. Galerkin method, along with the finite difference method (FDM), are employed to solve the wrinkle problem equation. The proposed method is able to satisfy the different boundary conditions for the wrinkle problem completely. The numerical results show that increasing the initial defect leads to a decrease in critical load and an increase in critical steering radius. To validate the theoretical model, experimental results are presented and compared with model-predicted results. It is shown that the model is well able to capture the trends and values of wrinkle formation wavelengths obtained from the experiment.

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Section: Methodsmentioning

confidence: 99%

Wrinkle Formation and Initial Defect Sensitivity of Steered Tow in Automated Fiber Placement

Kheradpisheh

Hojjati

2021

J. Compos. Sci.

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“…Two research centres have grown the field in recent years: The Chair of Carbon Composites at the Technical University of Munich (TUM) [12][13][14][15] and the Concordia Centre for Composites (CONCOM) [11,16,17]. The frameworks developed at the two institutions are similar in that they both take account of every constituent involved (i.e.…”

Section: Uob Confidentialmentioning

confidence: 99%

Hypo-viscoelastic modelling of in-plane shear in UD thermoset prepregs

Wang

Belnoue

Hallett

2021

Composites Part A: Applied Science and Manufacturing

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In-plane shear of prepreg material is one of the key deformation modes that affects defect generation in composites manufacturing processes such as Automated Fibre Placement (AFP) and Thermoforming. Recent characterisation of the evolution of uncured prepreg in-plane shear behaviour during manufacturing has revealed a strong influence of deformation rate and temperature on the measured response. In the present contribution, a phenomenological viscoelastic model for the observed behaviour is formulated using rate constitutive equations. Each of the components is related to an assumed micro-mechanical phenomenon (e.g. friction between the fibres, tensile loading of the fibres, etc). The proposed model is implemented into a user material subroutine for the Finite Element (FE) package Abaqus/Explicit. Model validation is performed by modelling experiments with loading programmes distinctly different from those used for material parameter extraction and it is concluded that state-of-the-art numerical models for AFP need to better represent in-plane shear.

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“…4,5 Compaction force is one of the most important process parameters for AFP, and many studies have shown that appropriate compaction force helps to improve prepreg tack levels and layup quality. [6][7][8][9][10][11] However, little attention has been paid to the compaction pressure (the force per unit area on prepreg layers, unit: Pa), which is more essential than compaction force (unit: N). At present, most of the researches on AFP process were carried out on flat mold, in which case the compaction pressure distribution is relatively even.…”

Section: Introductionmentioning

confidence: 99%

Compaction pressure distribution and pressure uniformity of segmented rollers for automated fiber placement

Jiang

et al. 2021

Journal of Reinforced Plastics and Composites

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For automated fiber placement onto molds with complex surfaces, uneven compaction pressure distribution limits tows number in a single sequence and affects layup quality. Compaction roller has a direct influence on the pressure distribution, but the relationship between the two has not been widely explored. In this paper, the segmented compaction roller is used, and a theoretical model of compaction pressure distribution for layup onto general surfaces is established by analyzing the contact between the roller and prepreg layers, followed by experimental validation. Based on the model, single-point pressure uniformity and whole-path pressure uniformity are proposed to quantitatively evaluate the pressure distribution. Furthermore, pressure distribution and pressure uniformity of segmented roller and common roller are compared, as well as the influence of the two pressure distribution on layup quality. The results show that the established model can predict pressure distribution and provide a basis for analyzing layup defects, and segmented rollers apply evener compaction pressure and help to improve layup quality.

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Effect of compaction roller on layup quality and defects formation in automated fiber placement

Cited by 41 publications

References 14 publications

Wrinkle Formation and Initial Defect Sensitivity of Steered Tow in Automated Fiber Placement

Wrinkle Formation and Initial Defect Sensitivity of Steered Tow in Automated Fiber Placement

Hypo-viscoelastic modelling of in-plane shear in UD thermoset prepregs

Compaction pressure distribution and pressure uniformity of segmented rollers for automated fiber placement

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