scholarly journals Generation of R-Curve from 4ENF Specimens: An Experimental Study

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
V. Alfred Franklin ◽  
T. Christopher
Keyword(s):  
Composite Materials ◽  
Fracture Energy ◽  
Epoxy Composite ◽  
Beam Theory ◽  
Fiber Direction ◽  
Crack Growth Resistance Curve ◽  
Aerospace Applications ◽  
Delamination Toughness ◽  
Theory Solution

The experimental determination of the resistance to delamination is very important in aerospace applications as composite materials have superior properties only in the fiber direction. To measure the interlaminar fracture toughness of composite materials, different kinds of specimens and experimental methods are available. This article examines the fracture energy of four-point end-notched flexure (4ENF) composite specimens made of carbon/epoxy and glass/epoxy. Experiments were conducted on these laminates and the mode II fracture energy, GIIC, was evaluated using compliance method and was compared with beam theory solution. The crack growth resistance curve (R-curve) for these specimens was generated and the found glass/epoxy shows higher toughness values than carbon/epoxy composite. From this study, it was observed that R-curve effect in 4ENF specimens is quite mild, which means that the measured delamination toughness, GIIC, is more accurate.

Evaluating the Mechanical Properties of 3D Woven Carbon-Epoxy Composite Materials Using Experimental Data and FEA Methods

2011 ◽  
Author(s):  
Mahdi Farahikia ◽  
Sunilbhai Macwan ◽  
Fereidoon Delfanian ◽  
Zhong Hu
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Composite Materials ◽  
Epoxy Composite ◽  
External Pressure ◽  
Fiber Direction ◽  
Strain Gages ◽  
Element Analysis ◽  
Test Specifications ◽  
Dog Bone

A series of tensile, compression and shear tests were carried out on carbon-epoxy composite materials to evaluate their mechanical properties. The experiments were set upin accordance with ASTM standards that best corresponded to the test specifications. Specimens were categorized into groups according to their dimensions and shape. Based on testing requirements, some were cut into rectangular and others into dog bone specimens to determine the effects of stress concentration. A number of specimens were reinforced at both ends by means of tabs which were bonded on both faces to reduce the effects of the external pressure exerted on them through the grips of the testing machines, and the rest of them were tested without any reinforcement tabs. All the specimens were tested until failure. Load, elongation (displacement) and strain data were recorded by means of strain gages and data acquisition systems. The experimental results obtained from similar tests on different groups are compared to examine the conformity of the results regardless of dimension and geometry, and are also verified by Finite Element Analysis (FEA). In addition, FEA is used to study different conditions, such as geometry, that could affect the final results. The experimental data are analyzed and effects of fiber direction on failure method are studied. It was concluded that shape and geometry factors as well as fiber direction influenced the failure method. The work, however, is still in progress and tests under conditions, such as elevated temperature, will be conducted to study other effects on the mechanical properties of 3D woven carbon-epoxy composites.

scholarly journals Low-temperature tension properties of glass-epoxy composite materials

2005 ◽  
pp. 123-134
Author(s):  
Slavisa Putic ◽  
Marina Stamenovic ◽  
Branislav Bajceta ◽  
Predrag Stajcic ◽  
Srdjan Bosnjak
Keyword(s):  
Tensile Strength ◽  
Composite Material ◽  
Composite Materials ◽  
Room Temperature ◽  
Epoxy Composite ◽  
Epoxy Composites ◽  
Tension Properties ◽  
Different Temperatures ◽  
Stereo Microscope

The aim of this paper was to present the determination of tensile strength Rm and modulus of elasticity Et of glass-epoxy composites at two different temperatures (at room temperature t=20?C, and at t =?50?C). Standard mechanical testing was carried out on glass woven-epoxy composite material with different structures (two specific weights of reinforcement, 210 g/m2 and 550 g/m2) and orientations (0?/90? and ?45?). Micromechanical analysis of failure was performed on a stereo microscope and SEM in order to determine real models and mechanisms of crack.

scholarly journals DETERMINATION OF MECHANICAL PROPERTIES OF COMPOSITE MATERIALS WITH DIFFERENT FILLERS POLYMER MATRIX

2021 ◽  
Vol 06 (02) ◽  
pp. 97-104
Author(s):  
Zaka Salimov Zaka Salimov ◽  
Matanat Jabiyeva Matanat Jabiyeva
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
Carbon Fiber ◽  
Epoxy Resin ◽  
Epoxy Composite ◽  
Compression Tests ◽  
Prepared Composite ◽  
Carbon Fiber Epoxy

In this study, the preparation and characterization of carbon fiber reinforced epoxy composites are aimed at today's increasing use of composite materials. In this study, composite materials consisting of unidirectional carbon fiber-epoxy resin were prepared and the effects of fiber inclination angle on layered epoxy composite materials were investigated using various characterization techniques. Composite materials were prepared by autoclave method. At the stage of characterization of prepared composite materials Scanning electron microscopy (SEM) has been applied for tensile, compression tests and characterization of fracture surfaces to determine the mechanical properties. Keywords: Carbon fiber,epoxy resin,polymer composite,mechanical properties.

Determination of In-plane Shear Strength of Unidirectional Composite Materials Using the Off-axis Three-point Flexure and Off-axis Tensile Tests

2010 ◽  
Vol 44 (21) ◽  
pp. 2487-2507 ◽  
Author(s):  
G. Vargas ◽  
F. Mujika
Keyword(s):  
Shear Strength ◽  
Composite Materials ◽  
Tensile Tests ◽  
Unidirectional Composite ◽  
Point Of View ◽  
Experimental Point ◽  
Plane Shear ◽  
Lift Off ◽  
Flexure Test

The aim of this work is to compare from an experimental point of view the determination of in-plane shear strength of unidirectional composite materials by means of two off-axis tests: three-point flexure and tensile. In the case of the off-axis three-point flexure test, the condition of small displacements and the condition of lift-off between the specimen and the fixture supports have been taken into account. Some considerations regarding stress and displacement fields are presented. The in-plane shear characterization has been performed on a carbon fiber reinforced unidirectional laminate with several fiber orientation angles: 10°, 20°, 30°, and 45°. Test conditions for both off-axis experimental methods, in order to ensure their applicability, are presented. Off-axis flexure test is considered more suitable than off-axis tensile test for the determination of in-plane shear strength.

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