Characterisation of inter-ply shear in uncured carbon fibre prepreg

Erland, Samuel; Dodwell, Tim; Butler, Richard

doi:10.1016/j.compositesa.2015.07.008

Cited by 43 publications

(31 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is marked by a change in friction response from one dominated by hydrodynamic lubrication to one dominated by boundary lubrication. A similar response is shown when it comes to the critical yield stress [19]. That is, τ c decreases upon heating, reaches a minimum value, and then increases again slightly.…”

Section: Pre-yield Behavioursupporting

confidence: 68%

“…The latter, j, highest within the hydrodynamic regime, begins at a maxima and decreases with an increase in temperature. Conversely, µ, highest during boundary lubrication, begins at a minima and increases with an increase in temperature [19]. These contradictory affects are related to the amount of surface resin present [19,28].…”

Section: Pre-yield Behaviourmentioning

confidence: 99%

“…The Stribeck Curve provides a visual for lubrication friction regimes, wherein the coefficient of friction is mapped against the Hershey Number, as shown in Figure 2.5 [34,44] decreases and inter-ply friction thus also decreases. However when the viscosity is low enough, this effect is no longer seen and, in fact, inter-ply friction is shown to increase [19,20,34,35]. This increase in friction at low viscosity has been associated with an insufficient buildup of film thickness, allowing for mechanical interaction between fibers.…”

Section: Inter-ply Friction Of Prepregmentioning

confidence: 99%

“…Erland et al [19] describe inter-ply shear using a viscoelasto-plastic model, wherein the viscoelastic contribution pertains to the pre-yield behaviour. The relation is given as:…”

Section: Pre-yield Behaviourmentioning

confidence: 99%

See 3 more Smart Citations

Core Movement During Processing of Sandwich Panels

Pawson¹,

Fernlund²

2019

SAMPE 2019 - Charlotte, NC

View full text Add to dashboard Cite

Core movement is a phenomenon that plagues sandwich panel fabrication during autoclave processing. External pressure can result in deformation of the core in its weak, lateral direction. This in turn, drags the facesheet plies inward. Parts displaying notable core movement are unfit for service and must be scrapped. Restraining plies, thereby preventing core movement, has become common practice in industrial processing of sandwich panels. Progress has been made in mitigating the risk of core movement through artificially increasing pressure within the core as well as through development of high friction resin/fiber systems. However, a complete understanding of the physics of the problem is still lacking. The focus of this research is to understand how processing conditions affect core movement and to gain a better understanding of the fundamental nature of core movement. Parameters investigated include, temperature, pressure, and a variety of structural features such as tie downs, core machining stabilization, and core chamfer angles. The problem is investigated using novel techniques. In-situ data collection is performed through use of displacement and in-core pressure sensors. Moreover, the entire event is filmed in real time using an autoclavable camera. This allowed for identification of the exact processing parameters during initiation and progression of core movement. Individual ply movement is determined post-processing. It was shown that failure pressure is dictated by viscosity at lower processing temperatures, but at high temperatures this is no longer the case. This implies a shift in the lubrication regime and alters the mechanics of the problem. A basic mechanical model describing the core movement process is outlined and the conditions necessary for core movement initiation are proposed. It was shown that core movement initiates at the chamfer radius and fluctuates between progressing through the core and down the chamfer edge. The results suggest that friction is the governing mechanism behind core movement initiation, which, if true, has important ramifications for sandwich panel design.

show abstract

Section: Pre-yield Behavioursupporting

confidence: 68%

Section: Pre-yield Behaviourmentioning

confidence: 99%

Section: Inter-ply Friction Of Prepregmentioning

confidence: 99%

“…Erland et al [19] describe inter-ply shear using a viscoelasto-plastic model, wherein the viscoelastic contribution pertains to the pre-yield behaviour. The relation is given as:…”

Section: Pre-yield Behaviourmentioning

confidence: 99%

See 2 more Smart Citations

Core Movement During Processing of Sandwich Panels

Pawson¹,

Fernlund²

2019

SAMPE 2019 - Charlotte, NC

View full text Add to dashboard Cite

show abstract

“…The influence of the friction coefficient was also investigated. Larberg and Akermo [52] and Erland et al [53] have shown that different but chemically similar prepreg systems can exhibit very dissimilar frictional behavior depending on the toughening strategy used (i.e., whether the thermoplastic particles are dispersed on the prepreg surface or not) and the processing conditions. Friction coefficients varying from g % 0 up to g ¼ 0:2 have been measured in the past.…”

Section: Interplymentioning

confidence: 99%

Consolidation-Driven Defect Generation in Thick Composite Parts

Belnoue

Nixon-Pearson

Thompson

et al. 2018

Journal of Manufacturing Science and Engineering

View full text Add to dashboard Cite

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.

show abstract

Effect of temperature aging of thermoset UD prepregs on inter‐ply friction behavior and formability in prepreg compression molding process

Zhang,

Han,

Liu

et al. 2024

Polymer Composites

View full text Add to dashboard Cite

Limited material out‐life of thermoset prepregs is unavoidable attributed to the slow crosslinking reaction between molecules and curing agents. Previous studies have explored the effects of temperature aging on the final mechanical properties of composites, but have been limited by the processing mismatch in compression molding. The research primarily focuses on the effects of forming temperature and ply angle of prepreg on inter‐ply friction behavior at various aging levels. The importance of inter‐ply friction on the forming quality is further discussed through the L‐shaped specimens forming with prepreg compression molding (PCM) process. Firstly, a comprehensive influence of aging on the properties of resin including cure kinetics, gel point, glass transition temperature (Tg) and viscosity of UD prepreg are characterized and discussed. And then, the influence of factors including resin aging, forming temperature and prepreg ply orientation on the inter‐ply friction are discussed. It can be found that the aging of prepreg reduce 26.47% of inter‐ply friction resistance under room temperature, and the increase of temperature can reduce inter‐ply friction resistance by 79.31%. Finally, the effect of aging on the forming quality is researched by PCM formed L‐shaped components. Results indicated that fresh prepreg with 20°C and prepreg with an aging level of 0.4 performed at 95°C exhibited poor formability, while prepreg with aging level of 0.2 at 95°C exhibited the best forming property. In general, this study provides a basic explain and a practical suggestion to the reuse of room temperature aging thermoset prepregs in PCM process.Highlights A comprehensive of basic properties of aged resin were characterized, as the basic principle for inter‐ply friction behavior analysis. The gel point and final mechanical properties of prepreg were tested, for judging the aged materials whether could be used continuously. The inter‐ply friction behaviors of aged prepregs under various forming temperatures were investigated. The influence of layup orientations on the inter‐ply frictional performance with various aging levels were explored. The effect of aging and forming temperature on the PCM formability were studied and a practical suggestion to the reuse of aged thermoset prepregs in PCM process was given.

show abstract

Characterisation of inter-ply shear in uncured carbon fibre prepreg

Cited by 43 publications

References 15 publications

Core Movement During Processing of Sandwich Panels

Core Movement During Processing of Sandwich Panels

Consolidation-Driven Defect Generation in Thick Composite Parts

Effect of temperature aging of thermoset UD prepregs on inter‐ply friction behavior and formability in prepreg compression molding process

Contact Info

Product

Resources

About