Anti-symmetric laminates for improved consolidation and reduced warp of tapered C-sections

Fletcher, Timothy; Butler, Richard; Dodwell, Tim

doi:10.1179/2055035914y.0000000010

Cited by 7 publications

(8 citation statements)

References 16 publications

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“…In both cases the shear strain increases incrementally as we move away from the axis of symmetry, reaching a maximum at the free edge. Thus if θ = π/2 and consolidation α = 12% [7,3], the corner consolidation example generates a maximum shear strain of γ cons. = 0.32, whilst the drape forming scenario requires a much greater shear strain of γ form = 0.94.…”

Section: Optimum Forming Parameters For Process Induced Shear Strainsmentioning

confidence: 99%

“…Fig. 1), part distortion [5,6] and poor consolidation [7]. To limit the formation of such defects, the characterisation of shear properties of materials is vital to not only determine optimal shear conditions for manufacturability, but to provide input parameters for process simulations [3] and manufacturing design methods [8].…”

Section: Introductionmentioning

confidence: 99%

“…Shear modulus here is denoted as S, where S is equivalent to K and G t of Eqs. (1)and(7). From[16] we see that h f ib.16h int.…”

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confidence: 99%

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Characterisation of inter-ply shear in uncured carbon fibre prepreg

Erland

Dodwell

Butler

2015

Composites Part A: Applied Science and Manufacturing

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Understanding the inter-ply shear behaviour of uncured carbon fibre prepreg is fundamental to avoiding process-induced defects during manufacturing of largescale components. Shear tests for AS4/8552 are compared to a one-dimensional viscoelastic-plastic model for inter-ply shear. The paper presents a methodology capable of determining the parameters of temperature, rate and pressure required for minimum resistance to movement of a prepreg. Investigating the joint strength and friction values individually shows that friction increases with temperature, contrary to previous work, and that the new value of joint strength is predominant at lower temperatures. Rate dependent variables are strongly linked to the resin behaviour, confirming the need for a viscoelastic model. Simple application to industrial scenarios is discussed along with more complex process modelling.

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Section: Optimum Forming Parameters For Process Induced Shear Strainsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characterisation of inter-ply shear in uncured carbon fibre prepreg

Erland

Dodwell

Butler

2015

Composites Part A: Applied Science and Manufacturing

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“…Such an enhanced design space for laminate selection provides greater scope for tailoring, especially in critical areas between regions where two laminates are blended (e.g across rib bays in aircraft wing skins), including effects of ply drop-offs. In particular, the induced coupling between in-and-out of plane behaviour could be utilised for beneficial purposes in geometrically non-symmetric structures [7,8], harnessed as a route to achieve novel structural responses [9,10] and offer greater design freedom for impact resistance [11].…”

Section: Introductionmentioning

confidence: 99%

Reconsidering Laminate Nonsymmetry

O’Donnell

2020

AIAA Journal

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Non-symmetric laminates are commonly precluded from composite design due to perceptions of reduced performance arising from in-and out-of-plane coupling. This coupling introduces warpage during cure -leading to raised stresses, together with diminished buckling and load carrying capacity. However, these reduced performance characteristics are rarely quantified and included in the design process, instead the "symmetric-only" paradigm remains pervasive at the cost of a significantly reduced design space. Warpage is largely driven by mismatch in the coefficients of thermal expansion between sub-laminates located above and below the mid-plane and can be predicted by classical laminate theory. Acknowledging that all symmetric laminates in multi-part structures have build stresses from assembly, we propose that subsets of non-symmetric laminates, that translate to similar raised stress levels, be considered for design. Challenging this "symmetric-only" design paradigm would permit greater design freedom and offer new routes to elastically tailor composite structures. Further analysis of structural performance is assessed in terms of reduced loading and buckling capacity.

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“…Although compaction mostly happens in the thickness direction, pressure forces in fiber direction may be created depending on the part geometry and mold concept. 5,21,28,29 Dodwell et al 5 analyze this mechanism for a C-shaped airplane frame manufactured by means of automated fiber placement technology. Consolidating the prepreg material over an external radius will shift the plies from a large initial radius to a much smaller radius.…”

Section: Introductionmentioning

confidence: 99%

An experimental characterization of wrinkling generated during prepreg autoclave manufacturing using caul plates

Weber

Englhard

Arent

et al. 2019

Journal of Composite Materials

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Out-of-plane ply wrinkling is a major quality issue for carbon fiber reinforced prepreg parts. Its triggers are numerous and not every influencing parameter is fully understood, yet. The research presented in this paper aims at providing a better insight into ply wrinkling generated during autoclave compaction using caul plates. A detailed description of the experimental set-up and the applied methodology is provided. Statistical analyses of varying influencing factors such as part thickness, geometry, tool–part interaction, and laminate lay-up are presented. This, in turn, generates a better understanding of their impact on fiber wrinkling risk and size. Part geometry and compaction deformation show the most significant influence on wrinkle size. However, for the given manufacturing concept, tool–part interaction also plays a significant role. It influences both the dimension and location of the wrinkles, as well as the existence and size of a critical flange length of the part. A noteworthy effect on wrinkle generation and size can also be observed when adding unidirectional plies to an otherwise fabric laminate.

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Anti-symmetric laminates for improved consolidation and reduced warp of tapered C-sections

Cited by 7 publications

References 16 publications

Characterisation of inter-ply shear in uncured carbon fibre prepreg

Characterisation of inter-ply shear in uncured carbon fibre prepreg

Reconsidering Laminate Nonsymmetry

An experimental characterization of wrinkling generated during prepreg autoclave manufacturing using caul plates

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