Improvement of interlaminar shear strength of 2.5D fabric laminated composites with short-cut web interlayer

2017 ◽  
Vol 37 (3) ◽  
pp. 261-269 ◽  
Author(s):  
Leilei Song ◽  
Jialu Li ◽  
Yufen Zhao ◽  
Xiaoming Chen ◽  
Li Chen
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Laminated Composites ◽  
Three Dimensional ◽  
Interlaminar Shear Strength ◽  
Bending Properties ◽  
Bending Tests ◽  
Testing Method ◽  
Short Beam ◽  
Interlaminar Shear

Abstract In this study, the short-cut web interlayer and three-dimensional (3D) needle-punched technique were used to improve the interlaminar shear strength (ILSS) of 2.5D fabric laminated composites. The ILSS was measured by the short beam testing method, and the tensile and bending tests were carried out to investigate the in-plane mechanical properties. Observations on microstructure and crack propagation were carried out. The damage mechanisms of different 2.5D fabric laminated composites were analyzed. The results showed that the short-cut web interlayer and 3D needle-punched technique resulted in the improvement of ILSS, and they affected the tensile and bending properties of 2.5D fabric laminated composites.

Failure mechanisms in three and four point short beam bending tests of unidirectional glass/epoxy

1992 ◽  
Vol 27 (4) ◽  
pp. 235-243 ◽  
Author(s):  
W C Cui ◽  
M R Wisnom ◽  
M Jones
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Shear Failure ◽  
Beam Theory ◽  
Interlaminar Shear Strength ◽  
Bending Test ◽  
Bending Tests ◽  
Four Point Bending ◽  
Short Beam ◽  
Interlaminar Shear

Three and four point bending tests are compared both analytically and experimentally. In all the three point bending tests, damage was observed under the loading roller in addition to the interlaminar shear failure, while in the four point bending tests, only interlaminar shear failure was observed. Therefore, this four point bending test is valid for measuring the interlaminar shear strength. From the finite element analysis, it is found that the roller diameter is a critical parameter in determining the stress concentrations in short beam tests. In order to avoid damage under the roller and thus to make the short beam test a valid means for measuring the interlaminar shear strength, the appropriate roller diameters should be chosen. The damage under the loading roller in the three point bending test basically reduces the effective specimen thickness and thus this test underestimates the interlaminar shear strength. The interlaminar shear cracks in the short beam tests were found to be randomly distributed in a region between 30 percent and 70 percent through the thickness from the top surface. This is due to the non-linear shear response which means that the shear stress distribution is more uniform near the middle of the section. Also the maximum value of the shear stress is lower than the maximum value given by beam theory. A non-linear shear correction factor is suggested to account for this effect and for the glass/epoxy composite tested here, the actual interlaminar shear strength is only about 83 percent of the apparent value from classical beam theory. The interlaminar shear crack does not occur at the location of maximum shear stress. This may be because there is insufficient energy to propagate a crack at this location.

Mechanical properties of multiwall carbon nanotubes/unidirectional carbon fiber-reinforced epoxy hybrid nanocomposites in transverse and longitudinal fiber directions

2021 ◽  
pp. 096739112098651
Author(s):  
Saeedeh Saadatyar ◽  
Mohammad Hosain Beheshty ◽  
Razi Sahraeian
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Epoxy Resin ◽  
Interlaminar Shear Strength ◽  
Lap Shear Strength ◽  
Transverse Tensile ◽  
Lap Shear ◽  
Longitudinal Fiber ◽  
Interlaminar Shear ◽  
Multiwall Carbon

Unidirectional carbon fiber-reinforced epoxy (UCFRE) is suffering from weak transverse mechanical properties and through-thickness properties. The effect of different amount (0.1, 0.3 and 0.5 phr which is proportional to 0.09, 0.27 and 0.46 wt%, respectively) of multiwall carbon nanotube (MWCNT), on transverse tensile properties, flexural strength, fracture toughness in transverse and longitudinal fiber directions, interlaminar shear strength and lap shear strength of UCFRE has been investigated. Dicyandiamide was used as a thermal curing agent of epoxy resin. MWCNT was dispersed in the epoxy resin by ultrasonic instrument and their dispersion state was investigated by scanning electron microscopy (SEM). The curing behavior of epoxy resin and its nanocomposites was assessed by differential scanning calorimetry. Results show that transverse tensile strength, modulus and strain-at-break were increased by 28.5%, 25% and 14%, respectively by adding 0.1 phr of MWCNT. Longitudinal flexural properties of UCFRE was not changed by adding different amount of MWCNT. Although longitudinal flexural strength was increased by 5% by adding 0.1 phr of MWCNT. Fracture toughness in transverse and longitudinal fiber directions was increased by 39% and 9%, respectively at 0.3 phr of MWCNT. Results also show that interlaminar shear strength and lap shear strength were increased at 0.3 phr of MWCNT by 8% and 5%, respectively. These increases in mechanical properties were due to the good adhesion of fibers to the matrix, interlocking and toughening action of MWCNT as revealed by SEM.

Modified Short Beam Shear Test for Measuring Interlaminar Shear Strength of Composites

AIAA Journal ◽  
2002 ◽  
Vol 40 (11) ◽  
pp. 2368-2370
Author(s):  
Kunigal Shivakumar ◽  
Felix Abali ◽  
Adrian Pora
Keyword(s):  
Shear Strength ◽  
Shear Test ◽  
Interlaminar Shear Strength ◽  
Short Beam ◽  
Beam Shear ◽  
Interlaminar Shear

Microstructure optimizations for improving interlaminar shear strength and self-healing efficiency of spread carbon fiber/epoxy laminates containing microcapsules

2020 ◽  
Vol 55 (1) ◽  
pp. 27-38
Author(s):  
Yasuka Nassho ◽  
Kazuaki Sanada
Keyword(s):  
Shear Strength ◽  
Carbon Fiber ◽  
Optical Microscope ◽  
Interlaminar Shear Strength ◽  
Self Healing ◽  
Short Beam ◽  
Healing Efficiency ◽  
Beam Shear ◽  
Interlaminar Shear ◽  
Carbon Fiber Epoxy

The purpose of this study is to improve interlaminar shear strength and self-healing efficiency of spread carbon fiber (SCF)/epoxy (EP) laminates containing microcapsules. Microencapsulated healing agents were embedded within the laminates to impart a self-healing functionality. Self-healing was demonstrated on short beam shear specimens, and the healing efficiency was evaluated by strain energies of virgin and healed specimens. The effects of microcapsule concentration and diameter on apparent interlaminar shear strength and healing efficiency were discussed. Moreover, damaged areas after short beam shear tests were examined by an optical microscope to investigate the relation between the microstructure and the healing efficiency of the laminates. The results showed that the stiffness and the apparent interlaminar shear strength of the laminates increased as the microcapsule concentration and diameter decreased. However, the healing efficiency decreased with decreasing the microcapsule concentration and diameter.

scholarly journals Surface Modification of Carbon Fibers by Grafting PEEK-NH2 for Improving Interfacial Adhesion with Polyetheretherketone

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 778 ◽  
Author(s):  
Elwathig. Hassan ◽  
Tienah. Elagib ◽  
Hafeezullah Memon ◽  
Muhuo Yu ◽  
Shu Zhu
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Carbon Fibers ◽  
Interfacial Adhesion ◽  
Mechanical Analysis ◽  
Interlaminar Shear Strength ◽  
Thermoplastic Composites ◽  
Negative Effects ◽  
Covalent Bonds ◽  
Interlaminar Shear

Due to the non-polar nature and low wettability of carbon fibers (CFs), the interfacial adhesion between CFs and the polyetheretherketone (PEEK) matrix is poor, and this has negative effects on the mechanical properties of CF/PEEK composites. In this work, we established a modification method to improve the interface between CFs and PEEK based chemical grafting of aminated polyetheretherketone (PEEK-NH2) on CFs to create an interfacial layer which has competency with the PEEK matrix. The changed chemical composition, surface morphology, surface energy, and interlaminar shear strength were investigated. After grafting, the interlaminar shear strength (ILSS) was improved by 33.4% due to the covalent bonds in the interface region, as well as having good compatibility between the interface modifier and PEEK. Finally, Dynamic Mechanical Analysis (DMA) and Scanning Electron Microscopy (SEM) observation also confirmed that the properties of the modified CF/PEEK composites interface were enhanced. This work is, therefore, a beneficial approach towards enhancing the mechanical properties of thermoplastic composites by controlling the interface between CFs and the PEEK matrix.

An Approach to Establish Interlaminar Micro Structure of 3-3 Connectivity in Laminated Composites

2011 ◽  
Vol 335-336 ◽  
pp. 244-248 ◽  
Author(s):  
Gang Liu ◽  
Dai Jun Zhang ◽  
Peng Zhang ◽  
Xiao Su Yi
Keyword(s):  
Shear Strength ◽  
Laminated Composites ◽  
Interlaminar Shear Strength ◽  
Carbon Fabric ◽  
Micro Structure ◽  
Dominant Mechanism ◽  
Pull Out ◽  
Interlaminar Shear ◽  
Novel Concept ◽  
Fracture Morphologies

This article is intended to outline a novel concept of interlaminar 3-3 connectivity of fiber-reinforced laminated composites. This microstructure is typically realized by using thorny ZnO whiskers exactly located in the interlayer of glass or carbon fabric for RTM. From the initial testing, the interlaminar shear strength (ILSS) is noted to increase up to 150% while retaining the most other in-plane properties. Mechanistic penetrating and pinning are considered to be the dominant mechanism of interlaminar toughening effect, with the evidence of the broken, fragmented and pull-out whiskers observed in the fracture morphologies.

scholarly journals Effect of Graphene Additive on Flexural and Interlaminar Shear Strength Properties of Carbon Fiber-Reinforced Polymer Composite

2020 ◽  
Vol 4 (4) ◽  
pp. 162
Author(s):  
Mohamed Ali Charfi ◽  
Ronan Mathieu ◽  
Jean-François Chatelain ◽  
Claudiane Ouellet-Plamondon ◽  
Gilbert Lebrun
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Carbon Fiber ◽  
Flexural Strength ◽  
Interlaminar Shear Strength ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Adhesion Properties ◽  
Reinforced Polymer ◽  
Interlaminar Shear

Composite materials are widely used in various manufacturing fields from aeronautic and aerospace industries to the automotive industry. This is due to their outstanding mechanical properties with respect to their light weight. However, some studies showed that the major flaws of these materials are located at the fiber/matrix interface. Therefore, enhancing matrix adhesion properties could significantly improve the overall material characteristics. This study aims to analyze the effect of graphene particles on the adhesion properties of carbon fiber-reinforced polymer (CFRP) through interlaminar shear strength (ILSS) and flexural testing. Seven modified epoxy resins were prepared with different graphene contents. The CFRP laminates were next manufactured using a method that guarantees a repeatable and consistent fiber volume fraction with a low porosity level. Short beam shear and flexural tests were performed to compare the effect of graphene on the mechanical properties of the different laminates. It was found that 0.25 wt.% of graphene filler enhanced the flexural strength by 5%, whilst the higher concentrations (2 and 3 wt.%) decreased the flexural strength by about 7%. Regarding the ILSS, samples with low concentrations (0.25 and 0.5 wt.%) demonstrated a decent increase. Meanwhile, 3 wt.% slightly decreases the ILSS.

Exploration relation between interlaminar shear properties of thin-ply laminates under short-beam bending and meso-structures

2017 ◽  
Vol 52 (17) ◽  
pp. 2375-2386 ◽  
Author(s):  
Chunfang Huang ◽  
Mingchang He ◽  
Yonglyu He ◽  
Jiayu Xiao ◽  
Jiangwei Zhang ◽  
...  
Keyword(s):  
Shear Strength ◽  
Carbon Fiber ◽  
Composite Laminates ◽  
Design Space ◽  
Interlaminar Shear Strength ◽  
Fiber Reinforced Polymer ◽  
Reinforced Polymer ◽  
Short Beam ◽  
Beam Bending ◽  
Interlaminar Shear

Carbon fiber reinforced polymer matrix composite laminates with standard thickness plies (0.125 mm) usually have weak interlaminar shear strength, meanwhile, for thin-thickness laminate structures such as aircraft wing skin, it is difficult to design a balanced laminate with the standard plies. It is a possible way to improve the interlaminar shear performance of carbon fiber reinforced polymer composite laminates and enlarge the design space of the thin-thickness structures by using thin-plies technology. In this paper, the interlaminar shear strength of carbon fiber/epoxy laminates with thin prepreg thickness subjected to short-beam bending is investigated. Unidirectional, cross-ply and quasi-isotropic laminate specimens were prepared by using prepregs with different ply thicknesses. Results show that, with decreasing of the ply thickness, higher interlaminar shear strength and smaller coefficient of variation of the data are obtained. Compared to laminates made by standard thickness prepreg, the laminates with thin-thickness prepreg exhibit more homogeneous microstructures and more regularly interlaminar shear stress distribution. This indicates that inherent anisotropy of the laminate composites is weakened in the thin-ply laminates and show pseudo-isotropic behavior. Especially in the case of ply thickness less than 0.020 mm, the interlaminar shear stress distributions of the cross-ply and quasi-isotropic laminate are almost the same with that of isotropic materials according to the classic laminate theory. On the other hand, as expected, the design space of the thin-thickness laminate structures will be increased since more ply number are allowed and superior interlaminar properties can be obtained due to the pseudo-isotropic behavior of the thin plies.

scholarly journals Process Chain Development for the Fabrication of Three-Dimensional Braided Oxide Ceramic Matrix Composites

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6338
Author(s):  
Martin Kolloch ◽  
Georg Puchas ◽  
Niels Grigat ◽  
Ben Vollbrecht ◽  
Walter Krenkel ◽  
...  
Keyword(s):  
Shear Strength ◽  
Three Dimensional ◽  
Ceramic Matrix Composites ◽  
Fiber Composites ◽  
Interlaminar Shear Strength ◽  
Oxide Ceramic ◽  
Two Dimensional ◽  
Process Chain ◽  
Fiber Volume ◽  
Interlaminar Shear

Fiber composites with a three-dimensional braided reinforcement architecture have higher fiber volume content and Z-fiber content compared to a two-dimensional braided reinforcement architecture; as a result, the shear strength increases. Porous oxide fiber composites (OFCs) have the inherent weakness of a low interlaminar shear strength, which can be specifically increased by the use of a three-dimensional fiber reinforcement. In this work, the braiding process chain for processing highly brittle oxide ceramic fibers is modified; as a consequence, a bobbin, which protects the filament, is developed and quantitatively evaluated on a test rig with regard to tension and filament breakage. Subsequently, a braiding process is designed which takes into account fiber-protecting aspects, and a three-dimensional reinforced demonstrator is produced and tested. After impregnation with an Al2O3-ZrO2 slurry, by either a prepreg process or a vacuum-assisted process, as well as subsequent sintering, the three-dimensional braid-reinforced OFC exhibits an interlaminar shear strength (ILSS) which is higher than that of two-dimensional braid- or fabric-reinforced samples by 64–95%. The influence of the manufacturing process on the relative macropore content is investigated and correlated with the mechanical properties.

The mechanical performance of the laminated aluminum-epoxy/glass fiber composites containing halloysite nanotubes: An experimental investigation

2020 ◽  
pp. 152808372096073
Author(s):  
Marwa A Abd El-baky ◽  
Mohamed A Attia
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Tensile Strain ◽  
Mechanical Performance ◽  
Flexural Modulus ◽  
Halloysite Nanotubes ◽  
Interlaminar Shear Strength ◽  
Plane Shear ◽  
Bearing Strength ◽  
Interlaminar Shear

In this study, the effect of different weight percentages (wt. %) of halloysite nanotubes (HNTs) on the mechanical performance of glass laminate aluminum (Al) reinforced epoxy (GLARE) was investigated. GLARE (3/2) laminates with quasi-isotropic lay-up, [Al/[(0°/90°)/(45°/−45°)]s/Al/[(0°/90°)/(45°/−45°)]s/Al] filled with 0, 0.25, 0.5, 1, 2 and 3 wt. % of HNTs were fabricated using hand lay-up followed by compression molding. To explore the effect of HNTs on the mechanical properties, tensile, flexural, in-plane shear, interlaminar shear, bearing and impact tests were conducted. Results demonstrated that the inclusion of 1 wt. % of HNTs into GLARE leads to maximum improvements of 35.67, 8.50, 28.85, 50.47, 50.27, 30.43, 23.73, 72.08, 30.74, and 51.52% in tensile strength, tensile strain, Young's modulus, modulus of toughness, flexural strength, flexural strain, in-plane shear strength, interlaminar shear strength, bearing strength, and impact strength, respectively, compared to pristine GLARE. An enhancement of 38.89% in the flexural modulus was attained by adding 0.5 wt. % of HNTs to GLARE compared to pristine GLARE. The tensile strength, tensile strain, modulus of toughness, flexural strength, flexural modulus, flexural strain, in-plane shear strength, and interlaminar shear strength of GLARE filled with 3 wt. % of HNTs are 0.91, 0.88, 0.91, 0.91, 0.71, 0.83, 0.85, and 0.91 times those of the original GLARE. But Young’s modulus, bearing strength, and impact strength are 1.10, 1.15 and 1.20 times those of the original GLARE. To investigate the fracture mechanism, field emission scanning electron microscope (FE-SEM) and energy-dispersive X-ray spectroscopy (EDX) were used. The microscopic images revealed that adding HNTs lead to the improvement in the interaction between the epoxy matrix and glass fiber, thereby improving the mechanical properties.

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