Time–temperature equivalence in the tack and dynamic stiffness of polymer prepreg and its application to automated composites manufacturing

Crossley, Richard; Schubel, Peter; Focatiis, Davide S.A. De

doi:10.1016/j.compositesa.2013.05.002

Cited by 46 publications

(43 citation statements)

References 16 publications

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“…A discussion on this topic for prepregs can be found at the end of ref. [86] as well as in other studies by the authors, [ 21,87,88 ] in which the TTS concept was repeatedly reapplied for further investigation.…”

Section: Experimental Studiesmentioning

confidence: 95%

“…This has led to the suggestion that the time‐temperature superposition principle (TTS) may be applicable toward prepreg tack which has been confirmed repeatedly for peel testing in subsequent studies. [ 21,86–88 ] Here, dynamic prepreg stiffness was found to increase monotonically as a function of feed rate while bell‐shaped curves are determined experimentally for tack. The rate dependency of tack, for example, for PSA, has traditionally been explained based on viscoelastic behavior exhibited by polymers during the debonding process.…”

Section: Experimental Studiesmentioning

confidence: 97%

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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: Experimental Studiesmentioning

confidence: 95%

Section: Experimental Studiesmentioning

confidence: 97%

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

2020

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“…Only the timeindependent part of the response to bending of the prepreg is taken into consideration and this may result in an overly stiff behavior. Second, the model neglects the effect of the adhesion between the plies [60], which may have an impact on the shape of the wrinkles [61]. Also, once the resin has bled out of the fiber bed, it is not accounted for anymore in the model.…”

Section: Identification Of Wrinkles Formation Mechanismmentioning

confidence: 99%

Consolidation-Driven Defect Generation in Thick Composite Parts

Belnoue

Nixon-Pearson

Thompson

et al. 2018

Journal of Manufacturing Science and Engineering

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Fiber waviness is one of the most significant defects that occurs in composites due to the severe knockdown in mechanical properties that it causes. This paper investigates the mechanisms for the generation of fiber path defects during processing of composites prepreg materials and proposes new predictive numerical models. A key focus of the work was on thick sections, where consolidation of the ply stack leads to out of plane ply movement. This deformation can either directly lead to fiber waviness or can cause excess fiber length in a ply that in turn leads to the formation of wrinkles. The novel predictive model, built on extensive characterization of prepregs in small-scale compaction tests, was implemented in the finite element software ABAQUS as a bespoke user-defined material. A number of industrially relevant case studies were investigated to demonstrate the formation of defects in typical component features. The validated numerical model was used to extend the understanding gained from manufacturing trials to isolate the influence of various material, geometric, and process parameters on defect formation.

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“…Furthermore, there is the possibility of excessive tack, so manual rework on defected placement paths is no longer possible. When the process temperature drops below a threshold value, there is the risk of insufficient tack [2] -the ability of the slit-tapes to stick to the surface -and subsequent process failure. It is therefore imperative to influence the process temperatures to a suitable window of operations during layup.…”

Section: Introductionmentioning

confidence: 99%