Cure-induced residual stresses for warpage reduction in thermoset laminates

Struzziero, Giacomo; Nardi, Davide; Sinke, J.; Teuwen, Julie J.E.

doi:10.1177/0021998320908631

Cited by 14 publications

(8 citation statements)

References 37 publications

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“…There are still other extrinsic parameters that were studied for the plate warpage, although not for the angle deviation. For example, the heating rate, cure temperature, cure time, and cooling rate are some parameters [36][37][38]. the spring-back deformation under the one-stage cure cycle was about 5% lesser than that under the two-stage cure cycle for parabolic antenna reflectors.…”

Section: Parameter Effects From Experimentsmentioning

confidence: 99%

An Overview of Angle Deviations of Fiber-Reinforced Polymer Composite Angular Laminates

Hwang

2023

Materials

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After manufacturing, fiber-reinforced polymer composite laminates may have residual stresses, resulting in warpage in flat structures and angle changes in angular sections. These shape distortions may cause fitting mismatch problems under high-level assembly, and extra efforts to fix these problems may be needed. The present paper only makes an overview of the angle deviation of angular composite laminates made of either thermoset matrix with autoclave curing or thermoplastic matrix with thermoforming. Depending on the positive or negative angle deviation, spring-back or spring-in behavior is observed. There are many parameters, including intrinsic and extrinsic parameters, that could affect the angle deviation. In the first part of this review paper, experimental results concerning the effects of the part angle, part thickness, lay-up sequence, corner angle, flange size, tool material, tool surface, and cure cycle are summarized. Spring-in angles are generally obtained in this part. In the second part, several prediction methods, such as simple equations and finite element methods, are compared to indicate the considered parameters. Some have good agreement and some have larger errors. The crucial differences may be dependent on the micromechanical theories and the input properties of the composite and the constituents.

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Section: Parameter Effects From Experimentsmentioning

confidence: 99%

An Overview of Angle Deviations of Fiber-Reinforced Polymer Composite Angular Laminates

Hwang

2023

Materials

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“…As a result, the tensile properties declined with increasing postcuring time and temperature. 35,36 The presence of paper allowed homogenous flow of the resin, and the presence of randomly oriented cellulose fibers (paper) resulted in a notable improvement in tensile properties of the composite loaded in transverse direction (Figure 3d). Tensile properties of FREC-0, FREC-28, and FREC-68 postcured at 80 C for 16 h are summarized in Table 1.…”

Section: Tensile Propertiesmentioning

confidence: 99%

Hybridization effect of cellulose paper and postcuring conditions on the mechanical properties of flax fiber reinforced epoxy biocomposite

Khalifa

Berndt

Shamitha

et al. 2022

J of Applied Polymer Sci

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An ever‐increasing rise in demand for sustainable materials has received significant attention in developing biocomposites for structural applications. In this regard, natural fibers replacing synthetic fibers as reinforcement in epoxy composite could be a significant gain toward sustainability, especially in automobile and structural applications. Herein, flax fiber/cellulose paper–reinforced epoxy biocomposite (FREC‐X) was fabricated via a vacuum infusion process. The influence of postcuring conditions (time and temperature) and cellulose paper density on the mechanical properties of FREC‐X was studied. The tensile strength and modulus of FREC‐X increased by 37% and 64%, respectively, upon the integration of paper. Postcuring FREC‐X further augmented the tensile and flexural properties of the composite, which could be attributed to the increase in cross‐linking of the epoxy and yields a strong polymer network. Fractography analysis confirmed that the composites integrated with paper showed fewer defects with improved interfacial adhesion. In addition, the water absorption and thickness swelling results revealed that the presence of cellulose paper marginally increased the water uptake and thickness swelling of FREC‐X. Furthermore, there was no significant change in the tensile and flexural properties of FREC‐X observed even after immersing in water for >200 h. Such properties of FREC‐X seen as a fascinating alternative to synthetic fibers and petroleum‐based epoxy and are promising material for sustainable development.

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“…There have been many techniques to reduce the generated thermal residual stress within a composite, including heat treatment after the curing process [ 12 ]; regulating curing cycles [ 13 , 14 ]; addition of various types of nanoscale particles to reduce any mismatch in mechanical properties of the constituents [ 15 , 16 ]; physical and chemical modifications of the constituents [ 17 ]; exploiting partial relaxation of residual stresses due to viscoelasticity [ 18 ]; developing low temperature curing resins [ 19 ], as well as fibre prestressing techniques [ 20 , 21 ]. Among these, fibre prestressing was first developed in the 1960s, which is able to reduce or eliminate residual stresses from the manufacturing of composites, without changing their composition, increasing mass or product dimensions [ 22 ].…”

Section: Introductionmentioning

confidence: 99%

Elastic Fibre Prestressing Mechanics within a Polymeric Matrix Composite

Chen

Wang

et al. 2023

Polymers

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The elastic fibre prestressing (EFP) technique has been developed to balance the thermal residual stress generated during curing of a polymeric composite. The continuous fibre reinforcements are prestressed and then impregnated into a polymeric matrix, where the prestress load is only removed after the resin is fully cured in order to produce an elastically prestressed polymeric matrix composite (EPPMC). Although the EFP is active in improving the static mechanical performance of a composite, its mechanics on dynamic mechanical performance and viscoelasticity of a composite is still limited. Here, we established a theoretical model in order to decouple the EFP principle, aiming to better analyse the underlying mechanics. A bespoke fibre prestressing rig was then developed to apply tension on a unidirectional carbon-fibre-reinforced epoxy prepreg to produce EPPMC samples with various EFP levels. The effects of EFP were then investigated by carrying out both static and dynamic mechanical testing, as well as the viscoelastic creep performance. It was found that there is an optimal level of EFP in order to maximise the prestress benefits, whilst the EFP is detrimental to the fibre/matrix interface. The EFP mechanisms are then proposed based on these observations to reveal the in-plane stress evolutions within a polymeric composite.

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Cure-induced residual stresses for warpage reduction in thermoset laminates

Cited by 14 publications

References 37 publications

An Overview of Angle Deviations of Fiber-Reinforced Polymer Composite Angular Laminates

An Overview of Angle Deviations of Fiber-Reinforced Polymer Composite Angular Laminates

Hybridization effect of cellulose paper and postcuring conditions on the mechanical properties of flax fiber reinforced epoxy biocomposite

Elastic Fibre Prestressing Mechanics within a Polymeric Matrix Composite

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