Effects of Processing Parameters on the Forming Quality of C-Shaped Thermosetting Composite Laminates in Hot Diaphragm Forming Process

Bian, Xiangnan; Gu, Yi; Sun, Junying; Li, M.; Liu, W. P.; Zhang, Z. G.

doi:10.1007/s10443-012-9310-7

Cited by 36 publications

(21 citation statements)

References 24 publications

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“…In the forming process, a hydrostatic pressure is applied to a dry fabric stack via a diaphragm to produce the final preform, similar to the commonly employed preforming step of prepregs for autoclave processing in the aerospace industry [1]. It used to be mainly associated with thermoplastic composite materials [2][3][4], but more recently has been used to process thermoset prepregs [1, [5][6][7] and produce binder-stabilised dry fabric preforms for liquid moulding routes [8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Double diaphragm forming simulation for complex composite structures

Chen

McGregor

Endruweit

et al. 2017

Composites Part A: Applied Science and Manufacturing

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A finite element (FE) material model has been developed to simulate the double diaphragm forming (DDF) process, to identify potential defects when forming complex 3D preforms from 2D biaxial non-crimp fabric plies. Three different metrics have been introduced to predict and characterise defects, which include local shear angles to determine ply wrinkling induced by over-shear, compressive strains in the primary fibre directions to determine bundle wrinkling, and tensile stresses in the primary fibre directions to determine fabric bridging . The FE simulation is in good agreement with experiments performed on a demonstrator component. Results indicate that fabric bridging occurs in large-curvature regions, which is the dominant defect in DDF. The axial tensile stress in fibres has been used as a measure to identify suitable positions and orientations for darts, to alleviate fabric bridging and improve surface conformity, whilst minimising the effect on the mechanical performance of the component.

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Section: Introductionmentioning

confidence: 99%

Double diaphragm forming simulation for complex composite structures

Chen

McGregor

Endruweit

et al. 2017

Composites Part A: Applied Science and Manufacturing

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“…The flange wrinkles were considered to be bending related since they began in the inner plies (tool side) and the outer plies appeared to be in tension. 3 Bending induced flange wrinkles related to the forming temperature has also been described by Bian et al, 11 Farnand et al, 12 and Kappel and Albrecht. 13 Belnoue et al performed a study on consolidation of a ramped, multi-stacked prepreg lay-up using two stiff mold halves.…”

Section: Introductionmentioning

confidence: 63%

Using tailored temperature variations to obtain flawless forming of multi-stacked unidirectional prepreg

Hallander

Grankäll

Eriksson

et al. 2020

Journal of Composite Materials

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In this article, tailored temperature zones are used to obtain improved quality during rapid, high pressure forming of multi-stacked unidirectional prepreg. Particularly in aerospace applications, commonly used forming processes for multi-stacked unidirectional prepreg are often considered a bottleneck in production since the forming cycle requires both heating and cooling ramps and consequently takes long time—often about 1 h. It is possible to speed up the process by using elevated pressure and temperature. However, higher pressure and temperature also increase the influence of pressure gradient-driven, in-plane material movement (squeeze flow). This typically appears as radius thinning when forming a C-spar geometry on a male mold. Decrease of lay-up temperature will decrease radius thinning, but due to obstructed interply slippage, instead bending-induced wrinkles appear on the spar flange. In this article, tailored temperatures at the radius and in the flange area are introduced by using a hot lay-up and a cold mold. The results show that temperature differences of 6℃–10℃ between the radius area and the flange edge of the lay-up decreases radius thinning while still avoiding bending-induced wrinkles. Except from the radius temperature also the stacking sequence and the choice of prepreg system showed a significant influence on the radius thinning.

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“…On the contrary, the deformation resistance is large, and defects easily occur when the temperature is too low. [ 25 ] Figure 4 illustrates the effect of temperature on the shear deformation. It is obvious that the force required to deform the bias extension specimen with compaction is temperature‐dependent.…”

Section: Resultsmentioning

confidence: 99%

Characterization of intra‐ply shear behaviors of unidirectional prepregs during hot diaphragm forming process

Zhao

Zhang

et al. 2020

Polymer Composites

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Intra-ply shear is the most important deformation mode in composite sheet forming. In this study, the intra-ply shear behaviors of cross-ply unidirectional carbon fiber/epoxy prepregs under double diaphragm compaction at different temperatures and cross-head rates were investigated by a home-made testing system. The experimental test results indicate that uniform temperature distribution and low forming speed in double diaphragm process help to obtain high-quality products. A modified model based on the temperature, cross-head rate and the level of compaction was proposed for shear angle prediction. Then fifth-degree polynomial and power functions combined with two rateindependent theories were used to calculate the shear force and modulus. The shear force and shear modulus are strongly influenced by the function that describing the relationship between the shear force and shear angle.

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Effects of Processing Parameters on the Forming Quality of C-Shaped Thermosetting Composite Laminates in Hot Diaphragm Forming Process

Cited by 36 publications

References 24 publications

Double diaphragm forming simulation for complex composite structures

Double diaphragm forming simulation for complex composite structures

Using tailored temperature variations to obtain flawless forming of multi-stacked unidirectional prepreg

Characterization of intra‐ply shear behaviors of unidirectional prepregs during hot diaphragm forming process

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