Properties of Composite Cylinders Fabricated by Bladder Assisted Composite Manufacturing (BACM)

2011 ◽  
Author(s):  
Jacob P. Anderson ◽  
M. Cengiz Altan
Keyword(s):  
Volume Fraction ◽  
Laminated Composite ◽  
Polymeric Composite ◽  
Void Content ◽  
Fiber Volume ◽  
Composite Manufacturing ◽  
Manufacturing Method ◽  
Three Point Bending ◽  
Cure Temperature ◽  
Composite Cylinders

An innovative manufacturing method, BACM (Bladder Assisted Composite Manufacturing), to fabricate geometrically complex, hollow parts made of polymeric composite materials is presented. BACM uses an internally heated bladder to provide the consolidation pressure at the required cure temperature, and thus produces high quality components. The feasibility of this manufacturing method is demonstrated by fabricating laminated composite cylinders using multiple cure pressures and wall thicknesses. The mechanical properties, energy consumed during the curing, and void content of the composite cylinders, are investigated in detail. The curing of composite cylinders was carried out by circulating heated air inside the bladder. Using the described heating method a number of 2-, 4-, and 6-ply composite cylinders made of E-glass/epoxy prepreg (Newport 321/7781) were prepared as test samples. Cylinders were cured at 121°C (250°F) for 2 hours using bladder pressures of 207 kPa (30 psi), 345 kPa (50 psi), 483 kPa (70 psi), and 621 kPa (90 psi). The mechanical behavior of the cylinders were characterized by compressing sample rings and loading ring segments in three-point bending. The fiber volume fraction and the void content of the cylinders were determined from resin burn-off experiments and density measurements. The cylinders produced using the BACM process were found to exhibit excellent surface quality. The elastic moduli, failure strength, and void contents of the cylinders were comparable to the values obtained from flat laminates produced by hot plate molding. Compared to conventional bladder manufacturing methods, the BACM process reduced the energy required to cure the cylinder by more than 50%.

Properties of Composite Cylinders Fabricated by Bladder Assisted Composite Manufacturing

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
J. P. Anderson ◽  
M. C. Altan
Keyword(s):  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Laminated Composite ◽  
Polymeric Composite ◽  
Internal Heating ◽  
Fiber Volume ◽  
Composite Manufacturing ◽  
Manufacturing Method ◽  
Cure Temperature ◽  
Composite Cylinders

An innovative manufacturing method, bladder assisted composite manufacturing (BACM), to fabricate geometrically complex, hollow parts made of polymeric composite materials is presented. Unlike the conventional bladder or diaphragm assisted curing processes, BACM uses an internally heated bladder to provide the consolidation pressure at the required cure temperature. The feasibility of this manufacturing method is demonstrated by fabricating laminated composite cylinders using multiple cure pressures and number of plies. The elastic moduli, failure strength, fiber volume fraction, and void contents of the cylinders were found to be comparable to the values obtained from flat laminates produced by hot plate molding of the same material. Compared to conventional bladder manufacturing methods, the BACM process reduced the energy required to cure the cylinders by almost 50% due to internal heating and insulated mold.

Flexural behavior of functionally graded polymeric composite beams

2021 ◽  
pp. 152808372110003
Author(s):  
M Atta ◽  
A Abu-Sinna ◽  
S Mousa ◽  
HEM Sallam ◽  
AA Abd-Elhady
Keyword(s):  
Flexural Strength ◽  
Volume Fraction ◽  
Stress Gradient ◽  
Polymeric Composite ◽  
Composite Beams ◽  
Functionally Graded ◽  
Flexural Behavior ◽  
Bending Test ◽  
Polymeric Composite Material ◽  
Fiber Volume

The bending test is one of the most important tests that demonstrates the advantages of functional gradient (FGM) materials, thanks to the stress gradient across the specimen depth. In this research, the flexural response of functionally graded polymeric composite material (FGM) is investigated both experimentally and numerically. Fabricated by a hand lay-up manufacturing technique, the unidirectional glass fiber reinforced epoxy composite composed of ten layers is used in the present investigation. A 3-D finite element simulation is used to predict the flexural strength based on Hashin’s failure criterion. To produce ten layers of FGM beams with different patterns, the fiber volume fraction ( Vf%) ranges from 10% to 50%. A comparison between FGM beams and conventional composite beams having the same average Vf% is made. The experimental results show that the failure of the FGM beams under three points bending loading (3PB) test is initiated from the tensioned layers, and spread to the upper layer. The spreading is followed by delamination accompanied by shear failures. Finally, the FGM beams fail due to crushing in the compression zone. Furthermore, the delamination failure between the layers has a major effect on the rapidity of the final failure of the FGM beams. The present numerical results show that the gradient pattern of FGM beams is a critical parameter for improving their flexural behavior. Otherwise, Vf% of the outer layers of the FGM beams, i.e. Vf% = 30, 40, or 50%, is responsible for improving their flexural strength.

Thermal cycle effects on laminated composite plates containing voids

2018 ◽  
Vol 53 (4) ◽  
pp. 489-501 ◽  
Author(s):  
Shambhu K Gupta ◽  
Mehdi Hojjati
Keyword(s):  
Shear Strength ◽  
Thermal Cycle ◽  
Composite Structures ◽  
Laminated Composite ◽  
Composite Plates ◽  
Interlaminar Shear Strength ◽  
Void Content ◽  
Manufacturing Method ◽  
Polished Cross Section ◽  
Interlaminar Shear

Composite structures are often cured in an autoclave to acquire the required space grade quality. Now the industry is focusing on the out of autoclave manufacturing method which leads to more voids inside laminate with respect to those manufactured in the autoclave. In the present work, the influence of voids on microcrack formation under thermal cycling and environmental conditions was analyzed. Thermal cycle experiments were performed using liquid nitrogen and oven, followed by microscopic observation of the polished cross-section of the 90° layered plies. Cracks were monitored, counted, and measured with respect to void and void free areas. Void content was characterized using microscopic and ImageJ software was used. It was observed that the microcracks will be formed both around the voids and in void free areas. As the number of thermal cycle increases, the number of microcrack around the voids increases much faster than compared to the void free areas. Also it was observed that most of microcracks were propagated in the transverse direction. Interlaminar shear strength was measured. Results indicate that interlaminar shear strength reduces as the number of cycle rises due to the increase in the microcrack density. Finite element method was used to simulate the process. The micro, meso, and macro model were created with respect to original samples voids and positions to calculate the stress distribution and its concentration. Good agreement between experiment and simulation was observed.

Micro-computed tomography analysis of natural fiber and bio-matrix tubular-braided composites

2019 ◽  
Vol 53 (28-30) ◽  
pp. 4003-4013 ◽  
Author(s):  
Brianna M Bruni-Bossio ◽  
Garrett W Melenka ◽  
Cagri Ayranci ◽  
Jason P Carey
Keyword(s):  
Computed Tomography ◽  
Natural Fiber ◽  
Volume Fraction ◽  
Void Content ◽  
Micro Computed Tomography ◽  
Braided Composites ◽  
Fiber Volume ◽  
Increasing Demand ◽  
Materials Used ◽  
Curing Method

There is an increasing demand for the use of “green”-based materials as reinforcement and matrix materials in composites. However, the ability of these natural-based materials to perform as consistently and reliably as conventional materials is still relatively unknown. A key importance in the viability of these materials is the evaluation of the content of voids and imperfections, which may affect the properties of the entire composite. In this study, the microstructure of tubular-braided composites manufactured from cellulose fibers and a partially bio-derived resin was studied with the use of micro-computed tomography. These methods were used to determine the effect of modifying braid angle, resin type, and curing method on fiber volume fraction, void volume, and void distribution. It was determined that the void content increased with the increase in braid angle, and vacuum-bagging reduced the total void content. The sample with the smallest braid angle produced with vacuum-bagged curing contained a void fraction of 1.5%. The results of this study proved that the materials used could be viable for further testing and development and that micro-computed tomography imaging is valuable for identifying how to improve consistency and minimize imperfections to create more accurate and reliable natural fiber-braided composites.

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.

J Integral of Steel Fiber Reinforced High Strength Concrete

2012 ◽  
Vol 476-478 ◽  
pp. 1568-1571
Author(s):  
Ting Yi Zhang ◽  
Guang He Zheng ◽  
Ping Wang ◽  
Kai Zhang ◽  
Huai Sen Cai
Keyword(s):  
High Strength Concrete ◽  
Fiber Volume Fraction ◽  
Steel Fiber ◽  
Volume Fraction ◽  
High Strength ◽  
Bending Test ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
Three Point Bending ◽  
Strength Concrete

Through the three-point bending test on the specimens of steel fiber reinforced high strength concrete (SFHSC), the effects of influencing factors including water-cement ratio (W/C) and the fiber volume fraction (ρf) upon the critical value(JC) of J integral were studied. The results show that the variation tendencies of JC are different under different factors. JC meets the linear statistical relation with W/C, ρf, respectively.

Analysis of Bending Behavior of Laminated Composite Beam

2015 ◽  
Vol 786 ◽  
pp. 421-425
Author(s):  
R. Arravind ◽  
M. Saravanan ◽  
K. Balasubramanian
Keyword(s):  
Composite Beam ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Laminated Composite ◽  
Layered Composite ◽  
Fiber Volume ◽  
Bottom Side ◽  
Bending Behavior ◽  
Laminated Composite Beam ◽  
The Impact

This paper discusses about the impact of fiber volume fraction on the bending behavior of a laminated composite beam. A two layered composite beam with upper layer made of glass fiber epoxy resin and reinforced with Kevlar at the bottom side of the beam is modeled and structural analysis is carried out. The analysis shows that the tensile strength increases with increase in fiber volume fraction. The compression strength decreases with increase in fiber volume fraction in the upper fiber where as increases in the bottom fiber and the obtained results are correlating with the experimental and analytical studies.

scholarly journals NUMERICAL OPTIMIZATION OF SANDWICH COMPOSITE STRUCTURE UNDER FLEXURAL LOAD

2019 ◽  
Vol 18 (4) ◽  
pp. 616-627
Author(s):  
Essam Z Fadhel
Keyword(s):  
Composite Structure ◽  
Volume Fraction ◽  
Element Model ◽  
Sandwich Composite ◽  
Fiber Volume ◽  
Three Point Bending ◽  
A Value ◽  
Bending Load ◽  
Core Volume ◽  
Sandwich Composite Structure

The structures of a sandwich composite have been utilized in the aerospace industry andengineering applications. Prediction of a theoretical composite construction's flexuralproperties is important for efficient composite products design. In this investigation, fourdifferent core shapes were used in the fabrication of the sandwich frames with constantvolume of sandwich composite structure in each case; these are hexagonal, rectangular,triangular and circular. The effect of core stiffeners number was studied to finding the beststiffeners number which gives the highest properties in strength using the finite elementanalysis.The material of the each face sheet is consisting from epoxy with four layers of a wovenfiberglass laminate construction, and the core stiffener material consists from epoxy matrixwith carbon fiber, the fiber volume fraction was 60% for both skins and core composites.The analysis of the three point bending load with a value of (10 kN) conducted byconstructing a finite element model, explained that the best shape of core was rectangularwhich give less deflection value of (11.939 mm) from the other shapes, for the sameproperties of material and constant core volume in each case. Also, it was determined theoptimum stiffeners number, for the rectangular core, was five stiffeners in longitudinaldirection and twelve stiffeners in transverse direction, gives strengthen structure.

Effects of vacuum pressure, inlet pressure, and mold temperature on the void content, volume fraction of polyester/e-glass fiber composites manufactured with VARTM process

2011 ◽  
Vol 45 (26) ◽  
pp. 2727-2742 ◽  
Author(s):  
Vishwanath R. Kedari ◽  
Basil I. Farah ◽  
Kuang-Ting Hsiao
Keyword(s):  
Glass Fiber ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Fiber Composite ◽  
Mold Temperature ◽  
Vacuum Pressure ◽  
Inlet Pressure ◽  
Void Content ◽  
Fiber Volume ◽  
Vartm Process

Vacuum-assisted resin transfer molding (VARTM) process is one of the liquid composite molding (LCM) processes aimed at producing high-quality composite parts. The void content and fiber volume fraction of a VARTM part can be affected by many parameters and is critical to the mechanical properties and the quality of the part. In this paper, a series of experiments were conducted with a heated dual pressure control VARTM setup for investigating the effects of vacuum pressure, inlet pressure, and mold temperature on the void content and fiber volume fraction of polyester/E-glass fiber composite. It was found that stronger vacuum and higher mold temperature can better control and increase the fiber volume fraction; however, such a combination of strong vacuum and high mold temperature may also require a reduced inlet pressure for minimizing the void content. The need of pressure reduction can be explained with the compatibility between Darcy's flow and capillary flow in the fiber preform and can be calculated based on the room temperature VARTM results. The experimental results suggest that high mold temperature, high vacuum, and appropriately reduced inlet pressure can produce a VARTM part with high fiber volume fraction and low void content.

Processing Effects on Formation of Microvoids and Hydraulic Fluid Absorption of Quartz/BMI Laminates

2015 ◽  
Author(s):  
Keith R. Hurdelbrink ◽  
Jacob P. Anderson ◽  
Zahed Siddique ◽  
M. Cengiz Altan
Keyword(s):  
Mechanical Properties ◽  
Relative Humidity ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Void Content ◽  
Hydraulic Fluid ◽  
Processing Conditions ◽  
Fluid Absorption ◽  
Fiber Volume ◽  
Fluid Content

Bismaleimide (BMI) resin with Quartz (AQ581) fiber reinforcement is desirable for systems requiring a high glass transition temperature, low dielectric properties, and high laminate mechanical properties. These properties make quartz/BMI an ideal composite material for complex aerospace structures, and are currently being used in various aircraft engine cowlings and radomes. In addition to moisture absorption, quartz/BMI composite laminates are often exposed to different types of hydraulic fluid contaminants, which may lead to anomalous absorption behavior over the service life of the composite structure. Variations in laminate processing conditions, such as prepreg preconditioning and fabrication cure pressure, can have a significant effect on microstructural features of fiber-reinforced composites. Microstructural features, such as fiber volume fraction and void content, can influence mechanical properties and long term absorption of moisture or other liquid contaminants. In this paper, the process-induced microstructure and hydraulic fluid absorption behavior of quartz/BMI laminates are presented. The laminates are fabricated from preconditioned prepregs and cured at different pressures to generate different levels of microvoids, while keeping the fiber volume fraction constant. Location, size and morphology of microvoids are investigated via SEM images obtained from laminates cured at different processing conditions. Composite samples were prepared and fully-immersed in hydraulic fluid at room temperature, and were not subjected to any prior degradation. The laminate samples immersed in hydraulic fluid exhibited clear non-Fickian absorption behavior, which was successfully predicted by the one-dimensional Hindered Diffusion Model (HDM). The degree of non-Fickian absorption behavior, or hindrance coefficient (μ), ranged from 0.30 to 0.72. Model prediction indicates that as the fabrication pressure increased, the maximum fluid content (M∞) decreased considerably. Additionally, a reduction in maximum fluid content was observed when lower relative humidity environments were used for prepreg preconditioning. A discernable difference was not observed in the absorption dynamics when the prepregs were preconditioned at greater than 70% relative humidity.

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