Influence of double vacuum debulking process on co-cured soft-patch carbon fibre composite repairs

Chong, H.M.; Wu, Zhanjun; Ng, Shu Pei; Subramanian, Alamelu Suriya; Liu, T.; Feih, S.

doi:10.1016/j.compositesb.2019.03.051

Cited by 10 publications

(2 citation statements)

References 26 publications

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“…[43][44][45] In the past, a number of researchers have used XCT to investigate microstructural changes in prepregs at different stages of the cure cycle. [11,12,[46][47][48] Moreover, recently, a small number of researchers developed XCT-aided geometrical models to study microstructural changes, such as air permeability and void formation in compaction-creep loaded uncured prepreg samples. [49][50][51] However, it is important to develop XCT-aided geometrical models in cured prepreg samples to observe the microstructural changes in real composite applications.…”

Section: Introductionmentioning

confidence: 99%

Viscoelastic and cyclic compaction response of prepregs tested under isothermal temperatures and various compaction speeds

et al. 2021

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Viscoelastic compaction/relaxation and cyclic compaction studies of uncured prepregs are of importance to understand the process parameters, such as mold closing forces and speed and the clamping force required to maintain a given thickness during molding, and so forth, for many composites manufacturing processes, including compression molding. In this study, viscoelastic compaction/ relaxation, and multi-cycle-compaction tests were performed on uncured glass/ epoxy prepreg specimens at elevated temperatures and variable compaction speeds up to a target fiber volume fraction of 0.65. At low temperatures, the relax-

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Section: Introductionmentioning

confidence: 99%

Viscoelastic and cyclic compaction response of prepregs tested under isothermal temperatures and various compaction speeds

et al. 2021

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“…Finally, mechanical characterization is carried out on two types of specimens to assess potential for USassisted thermoset prepreg repair: (1) short-beam shear test samples assembled through US consolidation to determine whether the process has an effect on interlaminar shear strength (ILSS) and (2) open-hole tensile test specimens repaired with soft co-cured patches or hard cobonded patches to estimate strength recovery. [16][17][18][19] Materials and methods…”

Section: Introductionmentioning

confidence: 99%

High-speed consolidation and repair of carbon fiber/epoxy laminates through ultrasonic vibrations: A feasibility study

Hoskins

Palardy

2020

Journal of Composite Materials

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Ultrasonic welding is a common fusion bonding technique to join unreinforced and reinforced thermoplastics. It is expected that applying ultrasonic vibrations to thermoset prepregs can produce heat generation to promote resin flow and consolidation. This paper discusses the feasibility of using ultrasonic vibrations as a high-speed repair technique for carbon fiber/epoxy prepregs to replace the traditional vacuum-bagging scarf setup. Three material types were investigated: out-of-autoclave unidirectional and plain weave prepregs (Cycom® 5320) and a general purpose twill weave prepreg (AS4/Newport 301). Two welding modes were considered: time and travel (vibrations stop once the desired vertical displacement is reached). For each mode, vibration time, travel, force, and amplitude were investigated. Cross-sectional analysis showed that void content equal to or below the vacuum-bagged samples could be achieved with ultrasonic consolidation to meet aerospace standards (≤2%). The following ultrasonic parameters were recommended to preserve prepreg tows integrity and minimize void content: vibration time below 1.0 s, travel between 12.5% and 50% of sample's initial thickness, force equal to or below 100 N, and amplitude below 41.3 μm. Temperature values recorded during the ultrasonic process reached the manufacturer's cure temperature range (120℃ to 180℃), with a predicted maximum degree of cure of 0.24. Interlaminar shear strength values were comparable for ultrasonically consolidated and vacuum-bagged samples. Soft and hard repair patches were applied to open-hole tensile coupons, with up to 50% strength recovery for both repair methods. Overall, ultrasonic consolidation has potential as a time- and cost-efficient repair method for thermoset prepregs.

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Influence of out‐of‐autoclave and autoclave manufacturing processes on mechanical properties of glass fiber‐reinforced epoxy composite

Dewangan,

Chakladar

2024

Polymer Composites

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In this study, an optimum process parameter space is proposed by comparing autoclave, oven curing and vacuum infusion process of manufacturing of GFRP composites. The process parameters, such as the degassing time of resin‐hardener mix, single or double vacuum bagging (DVB), fiber volume fraction and condition of the vacuum pump (VP) were considered. The novelty of the study shows that a VP Off and 5 min degassing condition exhibited 27%, 18% and 27% increase in tensile modulus, tensile strength and interlaminar shear strength as compared to the other methods. The normalized tensile strength, on the other hand, was comparable with DVB, oven and autoclave curing. A magnitude of 1.5 MPa of residual stress was measured with the help of x‐ray diffraction (XRD). This was verified by a Raman Spectroscopy, which showed a residual strain of 0.2% at a spectral peak of 1186 cm−1. The proposed methodology would assist the industries in choosing the right combination of process parameters required for a targeted tensile and interlaminar performance.Highlights Effect of out‐of‐autoclave and autoclave processes on the performance of GFRP was studied. Degassing time, vacuum bagging and Vacuum pump conditions were investigated. Vacuum pump Off and 5 min degassing time were found to be optimal. Tensile and Interlaminar shear strength were improved by 18% and 27% at optimal condition.

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Influence of double vacuum debulking process on co-cured soft-patch carbon fibre composite repairs

Cited by 10 publications

References 26 publications

Viscoelastic and cyclic compaction response of prepregs tested under isothermal temperatures and various compaction speeds

Viscoelastic and cyclic compaction response of prepregs tested under isothermal temperatures and various compaction speeds

High-speed consolidation and repair of carbon fiber/epoxy laminates through ultrasonic vibrations: A feasibility study

Influence of out‐of‐autoclave and autoclave manufacturing processes on mechanical properties of glass fiber‐reinforced epoxy composite

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