Optimization of the diaphragm forming process for continuous fibre-reinforced advanced thermoplastic composites

Delaloye, S.; Niedermeier, Michael

doi:10.1016/0956-7143(95)95004-i

Cited by 23 publications

(10 citation statements)

References 3 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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“…During the consolidation, a top pressure and a vacuum are applied to the diaphragm, and the prepregs conform to the tool shape. A typical temperature profile for one process cycle in diaphragm forming includes heating, soaking at a constant temperature (processing temperature), and cooling [8,10]. The cooling is addressed in this work because of its effect on the properties of final products.…”

Section: Temperature Profile In Sdf Single Diaphragm Formingmentioning

confidence: 99%

“…The prepregs are kept at the processing temperature and pressure for a sufficient time to achieve consolidation. Various methods have been used to heat and cool thermoplastic laminates during diaphragm forming [10]. Among the methods, conduction through the tool is highly effective since the molds are often aluminum alloy.…”

Section: Introductionmentioning

confidence: 99%

Processing and Nonisothermal Crystallization Kinetics of Carbon/PPS in Single Diaphragm Forming

Ning

Janowski

Vaidya

2009

Journal of Composite Materials

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Single diaphragm forming (SDF) has been used in manufacturing high-quality thermoplastic composite sheet parts with complex geometries. However, temperature gradients through the thickness may exist in the composites, especially for thick, high temperature, semicrystalline composites. The thermal gradient may introduce residual stresses, which may degrade the mechanical properties or warp the part. Therefore, investigating temperature profile through the thickness during processing can improve the quality of SDF composite parts. A laboratory scale SDF with a cooling system was built for the temperature study through the thickness. Carbon fiber reinforced polyphenylene sulphide (carbon/PPS) was used for the temperature study, and the effect of cooling rate on the nonisothermal crystallization of the carbon/PPS was also investigated using differential scanning calorimeter. The start crystallization temperature and the peak crystallization temperature decrease with increasing cooling rates. A combination of Avrami and Ozawa theory was successfully used in the work for describing the crystallization kinetics, and the crystallization activation energy was determined for the carbon fiber reinforced PPS.

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“…The resulting accuracy of this measuring methods referring to the CTE is 0.01 PPM 1/°K. The temperature of the specimen is measured by a thermoelectric couple (NiCr-Ni) within an accuracy of 0.5° C. To assure permanent contact of specimen and transducer rods, a controlled force can be adapted by the two springs (3,4). The resulting accuracy of this measuring methods referring to the CTE is 0.01 PPM 1/°K.…”

Section: Cth Measurements Of Piezoceramicsmentioning

confidence: 99%

<title>Design, manufacturing, and verification of piezoceramics embedded in fiber-reinforced thermoplastics</title>

et al. 1995

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Fiber reinforced thermoplastics offer substantial advantages over fiber reinforced thermosetts. Besides high specific stiffness and strength and excellent resistance to impact damage, especially with respect to the manufacturing process considerable cost reductions are possible'. The reason is the reduction of the processing times from hours to minutes. However the higher process temperatures close to the Curie temperature in the range from 2500 C to 400° C are expected to have a significant impact on the polarization of embedded piezocerarnic patches.Active structures require by definition embedded actuators and sensors as part of the load bearing structure. The success of the design philosophy of active structures is highly dependent on the manufacturing costs. For that reason fiber reinforced thermoplastics are supposed to be the ideal material for the host structure. Different manufacturing processes were applied to manufacture active test structures which are specifically designed with respect to the manufacturing process used. The embedding process of the active elements include the electrical insulation and wiring. Moreover the coefficient of thermal expansion (CII) of a typical PZT type ceramic was measured over a wide temperature range to understand the thermomechanical loading of the piezoceramic due to the manufacturing process.Moreover the electromechanical parameters of the active elements before and after the manufacturing process were measured. For this purpose a special test equipment has been developed. Furthermore the problem of thermal depolarization is touched.Basically it turns out that in spite of high processing temperatures the embedding of piezoceramics in fiber reinforced thermoplastics is feasible. The repolarization process of embedded piezoceramics is optimized for a given type of piezocerainics.

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Optimization of the diaphragm forming process for continuous fibre-reinforced advanced thermoplastic composites

Cited by 23 publications

References 3 publications

Double diaphragm forming simulation for complex composite structures

Double diaphragm forming simulation for complex composite structures

Processing and Nonisothermal Crystallization Kinetics of Carbon/PPS in Single Diaphragm Forming

<title>Design, manufacturing, and verification of piezoceramics embedded in fiber-reinforced thermoplastics</title>

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