Time-dependent wrinkle formation during tow steering in automated fiber placement

Bakhshi, Nima; Hojjati, Mehdi

doi:10.1016/j.compositesb.2019.02.034

Cited by 27 publications

(21 citation statements)

References 15 publications

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“…Wrinkles can be observed when the steering radius reaches a critical minimum. [ 35 ] A number of studies have examined the minimum steering radius of defect‐free lay‐up experimentally. [ 11,36–38 ]…”

Section: Role Of Prepreg Tack In Afp/atlmentioning

confidence: 99%

Prepreg tack: A review of mechanisms, measurement, and manufacturing implication

2020

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The stickiness of prepregs (tack) is considered a decisive material property for the success of high‐quality composite manufacturing by automated lay‐up processes such as automated fiber placement (AFP) or automated tape laying (ATL). Adverse control of prepreg tack can easily result in laminate defects or machine breakdown, which are highly undesirable considering the tremendous machinery and material costs of these processes. Prepreg tack is governed by a complex interaction of adhesive and cohesive phenomena that are influenced by machine and environmental parameters of the production process as well as by intrinsic properties of the prepreg material itself. This review aims at providing a condensed insight into the current state of research on prepreg tack. Therefore, experimental studies including the discussion of utilized tack measurement methods as well as model approaches to prepreg tack are reviewed. The findings are discussed against the background of fundamental mechanisms, the strong interdependency of influencing parameters and the challenge of translating measured tack data into an enhanced AFP/ATL process stability by process adjustment.

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Section: Role Of Prepreg Tack In Afp/atlmentioning

confidence: 99%

Prepreg tack: A review of mechanisms, measurement, and manufacturing implication

2020

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“…A careful control and selection of process parameters [54][55][56][57][58] (i.e., heating temperature, compaction pressure, deposition rate), machine trajectories (i.e., steering radius), together with material parameter (i.e., tackiness and tow width), is of crucial importance for obtaining a highquality, defect-free laminate. Bakhshi et al [55] carried out experimental and analytical studies to understand the time-dependent wrinkle formation during tow steering in AFP. The analytical model to describe wrinkle formation accounts for process parameters (e.g., temperature, radius, compaction force, speed) together with interface properties (tack).…”

Section: Steeringmentioning

confidence: 99%

“…Bakhshi et al [55] carried out experimental and analytical studies to understand the time-dependent wrinkle formation during tow steering in AFP. The analytical model to describe wrinkle formation accounts for process parameters (e.g., temperature, radius, compaction force, speed) together with interface properties (tack).…”

Section: Steeringmentioning

confidence: 99%

“…Rajan et al [61] performed experimental studies using Stereo-DIC to obtain in-situ measurements for quantifying out-of-plane wrinkle formation and in-plane deformations occurring . Schematic illustration of an anisotropic plate on elastic foundation illustrating an approach by Béakou et al [54] and Hörmann [51] to describe out-of-plane tape buckling for a steered tape during automated fiber placement, modified from [51,54,55]. Rajan et al [61] performed experimental studies using Stereo-DIC to obtain in-situ measurements for quantifying out-of-plane wrinkle formation and in-plane deformations occurring during automated fiber placement (AFP).…”

Section: Steeringmentioning

confidence: 99%

“…Schematic illustration of an anisotropic plate on elastic foundation illustrating an approach by Béakou et al[54] and Hörmann[51] to describe out-of-plane tape buckling for a steered tape during automated fiber placement, modified from[51,54,55].…”

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confidence: 99%

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Mechanisms of Origin and Classification of Out-of-Plane Fiber Waviness in Composite Materials—A Review

2020

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Out-of-plane fiber waviness, also referred to as wrinkling, is considered one of the most significant effects that occur in composite materials. It significantly affects mechanical properties, such as stiffness, strength and fatigue and; therefore, dramatically reduces the load-carrying capacity of the material. Fiber waviness is inherent to various manufacturing processes of fiber-reinforced composite parts. They cannot be completely avoided and thus have to be tolerated and considered as an integral part of the structure. Because of this influenceable but in many cases unavoidable nature of fiber waviness, it might be more appropriate to consider fiber waviness as effects or features rather than defects. Hence, it is important to understand the impact of different process parameters on the formation of fiber waviness in order to reduce or, in the best case, completely avoid them as early as possible in the product and process development phases. Mostly depending on the chosen geometry of the part and the specific manufacturing process used, different types of fiber waviness result. In this study, various types of waviness are investigated and a classification scheme is developed for categorization purposes. Numerous mechanisms of wrinkling were analyzed, leading to several recommendations to prevent wrinkle formation, not only during composite processing, but also at an earlier design stage, where generally several influence factors are defined.

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Compression and interlaminar shear behavior of steered laminates manufactured by automated fiber placement

Zheng,

Tang,

et al. 2024

Polymer Composites

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Variable stiffness (VS) composite structures can significantly reduce weight by adjusting fiber orientation. However, in current designs, the directional properties of composites cannot be fully utilized due to the lack of comprehensive mechanical characterization of VS laminates. This paper aims to investigate the compressive and out‐of‐plane bending behavior of steered laminates. Firstly, the critical steering radius theory was studied and derived. Secondly, five steered laminates with different radii and one “baseline” laminate were designed, manufactured, and tested to examine the effects of fiber steering on compressive and interlaminar shear strength (ILSS). The results indicate that, compared to the “baseline” laminate, the steered laminates exhibit a decreasing trend in both compressive strength and ILSS, with the maximum reductions being 32.1% in compressive strength and 9% in shear strength. Meanwhile, the microstructure was observed to gain an in‐depth understanding of the changes in the mechanical properties of the steered laminates. This study comprehensively evaluates the mechanical performance of steered laminates and provides appropriate steering limits for the design and manufacture of VS structures.Highlights The critical steering radius theory was studied and derived. Five steered laminates with different radii and one “baseline” laminate were designed, manufactured, and tested to examine the effects of fiber steering on compressive and ILSS. The microstructure was observed to gain an in‐depth understanding of the changes in the mechanical properties of the steered laminates.

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Time-dependent wrinkle formation during tow steering in automated fiber placement

Cited by 27 publications

References 15 publications

Prepreg tack: A review of mechanisms, measurement, and manufacturing implication

Prepreg tack: A review of mechanisms, measurement, and manufacturing implication

Mechanisms of Origin and Classification of Out-of-Plane Fiber Waviness in Composite Materials—A Review

Compression and interlaminar shear behavior of steered laminates manufactured by automated fiber placement

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