Void content and interfacial properties of composite laminates under different autoclave cure pressure

2016 ◽  
Vol 24 (5) ◽  
pp. 529-540 ◽  
Author(s):  
Tengfei Chang ◽  
Lihua Zhan ◽  
Wei Tan ◽  
Shujian Li
Keyword(s):  
Composite Laminates ◽  
Interfacial Properties ◽  
Void Content ◽  
Cure Pressure

Pressurized Infusion: A New and Improved Liquid Composite Molding Process

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
M. Akif Yalcinkaya ◽  
Gorkem E. Guloglu ◽  
Maya Pishvar ◽  
Mehrad Amirkhosravi ◽  
E. Murat Sozer ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Composite Laminates ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Compaction Pressure ◽  
External Pressure ◽  
Void Content ◽  
Liquid Composite Molding ◽  
Molding Process ◽  
Fiber Volume

Vacuum-assisted resin transfer molding (VARTM) has several inherent shortcomings such as long mold filling times, low fiber volume fraction, and high void content in fabricated laminates. These problems in VARTM mainly arise from the limited compaction of the laminate and low resin pressure. Pressurized infusion (PI) molding introduced in this paper overcomes these disadvantages by (i) applying high compaction pressure on the laminate by an external pressure chamber placed on the mold and (ii) increasing the resin pressure by pressurizing the inlet resin reservoir. The effectiveness of PI molding was verified by fabricating composite laminates at various levels of chamber and inlet pressures and investigating the effect of these parameters on the fill time, fiber volume fraction, and void content. Furthermore, spatial distribution of voids was characterized by employing a unique method, which uses a flatbed scanner to capture the high-resolution planar scan of the fabricated laminates. The results revealed that PI molding reduced fill time by 45%, increased fiber volume fraction by 16%, reduced void content by 98%, improved short beam shear (SBS) strength by 14%, and yielded uniform spatial distribution of voids compared to those obtained by conventional VARTM.

Effect of random vibration processing on void content in composite laminates

2018 ◽  
Vol 40 (8) ◽  
pp. 3122-3130 ◽  
Author(s):  
Xiaobo Yang ◽  
Lihua Zhan ◽  
Chengbiao Jiang ◽  
Xing Zhao ◽  
Chenglong Guan
Keyword(s):  
Composite Laminates ◽  
Random Vibration ◽  
Void Content

Infra-Red Thermography based Inspection of Hybrid Composite Laminates under Flexure Loading

2018 ◽  
Vol 10 (1) ◽  
Author(s):  
R. Bhoominathan ◽  
P. Divyabarathi ◽  
R. Manimegalai ◽  
T. Nithya ◽  
S. Shanmugapriya
Keyword(s):  
Composite Laminates ◽  
Volume Fraction ◽  
Void Content ◽  
Destructive Testing ◽  
Flexural Loading ◽  
Infra Red ◽  
Before And After ◽  
Cfrp Composite ◽  
Structural Parts ◽  
Non Destructive

Generally, the aircraft structural parts are economically high in cost so the materials need to be inspected for defects or damages using various non-destructive testing (NDT) methods like ultrasonic, thermography and acoustic emission. The aim of this project is to characterize the defects in composite laminates before and after the flexural loading using infra-red thermography NDT method. GFRP and hybrid (GFRP+CFRP) composite laminates are fabricated with different orientation such as uni-directional, cross ply, anti-symmetric and angle ply and then tested under flexural loading according to ASTM D790 standard. The volume fraction of the fibre and matrix needs to be found out to know the void content and the mixing ratio of reinforcement and binder.

scholarly journals Influences of Fibre Surface Treatment and Solvent Species on RTMED Silica Fibre/Phenolics Composites

2006 ◽  
Vol 15 (6) ◽  
pp. 096369350601500 ◽  
Author(s):  
Baichen Wang ◽  
Yudong Huang ◽  
Ping Chen ◽  
Yu Gao
Keyword(s):  
Phenolic Resin ◽  
Fibre Surface ◽  
Interfacial Properties ◽  
Void Content ◽  
Fibre Reinforcement ◽  
Drift Spectroscopy ◽  
Rtm Process ◽  
Interlaminar Shear ◽  
Diffuse Reflectance Infrared ◽  
Silica Fibre

In this study the effects of solvent species and silane coupling agent on the resin transfer moulded (RTMed) silica fibre/phenolics composites were investigated. Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy and wettability measurement were carried out. The interlaminar shear strength (ILSS) measurements and morphological observations of the silica fibre/phenolics composites were also performed. The interactions occurring between silica fibre and the components of phenolics solution affect the dynamic adsorption behaviour of phenolic resin onto fibre reinforcement. The competitive adsorption of solvent onto silica fibre suppresses that of phenolic resin. Fibre surface silanization with γ-aminopropyl-triethoxysilane (γ-APS) leads to the improvement of mechanical interfacial properties of silica fibre/phenolics composites on one hand and decreases inhomogeneities of resin distribution and mechanical interfacial properties of the RTM product on the other. For the first time it has shown that the RTM process of silica fibre/phenolics composites is highly solvent dependent. Phenolics form distribution gradient in RTM mould with respect to isomeric composition under the effect of solvent, which result, to varying extent, in the inhomogeneity of void content and thus ILSS of the resulting product. Our work gives an insight into the role of organic solvent in RTM processing and this will help in choosing the best possible solvent for the solution impregnation system.

Detection of Voids in Carbon/Epoxy Laminates and Their Influence on Mechanical Properties

2017 ◽  
Vol 25 (5) ◽  
pp. 371-380 ◽  
Author(s):  
Luca Di Landro ◽  
Aurelio Montalto ◽  
Paolo Bettini ◽  
Stefania Guerra ◽  
Fabrizio Montagnoli ◽  
...  
Keyword(s):  
Composite Laminates ◽  
Mechanical Performance ◽  
Thermal Analyses ◽  
Void Content ◽  
Processing Conditions ◽  
Micro Computed Tomography ◽  
Sem Image ◽  
Beam Shear ◽  
Mechanical Performances ◽  
Curing Cycle

Defects, such as voids and delaminations, may significantly reduce the mechanical performance of components made of composite laminates. Distributed voids and porosity are generated during composite processing and are influenced by prepreg characteristics as well as by curing cycle parameters. On the basis of rheological and thermal analyses, as well as observations of laminates produced by different processing conditions, curing pressure appears the most influent factor affecting the void content. This work compares different methods for void analysis and quantitative evaluation (ultrasonic scan, micro-computed tomography, acid digestion, SEM image analysis) evidencing their applicative limitations. Carbon/epoxy laminates were produced in autoclave or oven by vacuum bag technique, using different processing conditions, so that void contents ranging from 0% to 7% volume were obtained. Effects of porosity over laminates mechanical performances are analysed. The results of tensile and compressive tests are discussed, considering the effect that different curing cycles have over void content as well as over fibre/resin fraction. Interlaminar strength, as measured by short beam shear tests, which is a matrix-dominated property, exhibits a reduction of failure strength up to 25% in laminates with the highest void content, compared to laminates with no porosity.

Predicting Formation of Manufacturing Defects in Contoured Composites

2019 ◽  
Vol 64 (4) ◽  
pp. 1-15 ◽  
Author(s):  
Guillaume Seon ◽  
Yuri Nikishkov ◽  
Andrew Makeev ◽  
Lauren Fergusson
Keyword(s):  
Finite Element ◽  
Manufacturing Process ◽  
Composite Laminates ◽  
Defect Formation ◽  
Radius Of Curvature ◽  
Void Content ◽  
Consolidation Process ◽  
Closed Cavity ◽  
Manufacturing Defects ◽  
Early Stages

Composite helicopter rotor components are typically thick and often have areas with a tight radius of curvature, which make them especially prone to process-induced defects, including wrinkles and voids at ply interfaces. Such flaws cause high rejection rates in production of flight-critical components and structures. This work seeks to fill the gaps in understanding generation of the noted defects in contoured polymer–matrix composite laminates. In particular, understanding and modeling defect formation at the early stages of the manufacturing process might be the missing link to enable the development of practical engineering solutions allowing for better control of the manufacturing process of contoured composite parts. In this work, an approach based on a continuum description of the uncured prepreg material, including the initial bulk or void content, and finite element modeling (FEM) is used to simulate the consolidation process at the early stages of manufacturing of contoured laminates. The simulation predicts instabilities leading to formation of both wrinkles and voids at ply interfaces during laminate debulking or vacuum consolidation. Applicability of the method to consolidation in both closed-cavity and open-face tooling is also demonstrated. FEM results show good correlation with X-ray computed tomography data. This work also introduces a new simulation concept based on finite element and discrete modeling of voids at ply interfaces to improve the accuracy of predicting their evolution during the debulking operations.

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