Effect of Interphases on Micro and Macromechanical Behavior of Hexagonal-Array Fiber Composites

1990 ◽  
Vol 57 (4) ◽  
pp. 956-963 ◽  
Author(s):  
J. D. Achenbach ◽  
H. Zhu
Keyword(s):  
Fiber Composite ◽  
Volume Ratio ◽  
Fiber Composites ◽  
Effective Moduli ◽  
Hexagonal Array ◽  
Fiber Volume ◽  
Unidirectional Fiber Composite ◽  
Circumferential Tensile Stress ◽  
The Matrix ◽  
Stress And Deformation

The effect of interphase stiffness on microstresses and macromechanical behavior has been investigated for transverse loading of an hexagonal-array unidirectional fiber composite. The interphase is modeled by a layer which resists radial extension and circumferential shear deformation. Taking advantage of the periodicity of the medium, the states of stress, and deformation in a basic cell have been analyzed numerically by the use of the boundary element method. The circumferential tensile stress along the matrix side of the interphase and the radial stress in the interphase have been analyzed for various values of the interphase parameters and the fiber volume ratio. The micromechanical results have also been used to determine the effect of interphase stiffness on the effective moduli. The calculated values have been compared with analytical results that were adjusted for interphase stiffness.

Determination of fiber volume fraction in a cured laminate

2021 ◽  
pp. 002199832110112
Author(s):  
Qing Yang Steve Wu ◽  
Nan Zhang ◽  
Weng Heng Liew ◽  
Vincent Lim ◽  
Xiping Ni ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Fiber Volume Fraction ◽  
Evaluation Method ◽  
Volume Fraction ◽  
Matrix Material ◽  
Volume Ratio ◽  
Gravimetric Analysis ◽  
Fiber Volume ◽  
Laser Ultrasonic ◽  
The Matrix

Propagation of ultrasonic wave in Carbon Fiber Reinforced Polymer (CFRP) is greatly influenced by the material’s matrix, resins and fiber volume ratio. Laser ultrasonic broadband spectral technique has been demonstrated for porosity and fiber volume ratio extraction on unidirection aligned CFRP laminates. Porosity in the matrix materials can be calculated by longitudinal wave attenuation and accurate fiber volume ratio can be derived by combined velocity through the high strength carbon fiber and the matrix material with further consideration of porosity effects. The results have been benchmarked by pulse-echo ultrasonic tests, gas pycnometer and thermal gravimetric analysis (TGA). The potentials and advantages of the laser ultrasonic technique as a non-destructive evaluation method for CFRP carbon fiber volume fraction evaluation were demonstrated.

Toughness of ECC Evaluated by Nominal Fracture Energy

2012 ◽  
Vol 238 ◽  
pp. 57-60 ◽  
Author(s):  
Shu Ling Gao ◽  
Wei Shao ◽  
Jin Li Qiao ◽  
Ling Wang
Keyword(s):  
Glass Fiber ◽  
Fracture Energy ◽  
Steel Fiber ◽  
Volume Ratio ◽  
Fiber Glass ◽  
Fiber Volume ◽  
High Durability ◽  
The Matrix ◽  
Pva Fiber ◽  
Very High

ECC (Engineered Cementitious Composites) has ultra-high toughness and can be used in the zone needing the ultra-high tensile strain and very high durability. In order to investigate the toughness of ECC, the normal fracture energy GFis calculated and compared with ordinary concrete. The influence of the matrix (fly ash, silicon fume), the fiber (glass fiber, steel fiber and PVA fiber) and the fiber volume ratio on the GFof ECC are analyzed. The research indicates that silicon fume and glass fiber, steel fiber are all not able to be used in ECC. But flash ash and PVA fiber are very suit for using in ECC, the toughness of ECC increases with the increase of their content.

Study on Enhancement of Mechanical Strength by Knotted Shape Memory Alloy Fiber in TiNi Fiber Composites

2008 ◽  
Vol 385-387 ◽  
pp. 421-424
Author(s):  
Yong Li Zhao ◽  
Jie Li ◽  
Ming Jin
Keyword(s):  
Shape Memory Alloy ◽  
Mechanical Strength ◽  
Shape Memory ◽  
Fiber Composite ◽  
Stress Transfer ◽  
Fiber Composites ◽  
Tension Test ◽  
Fiber Tension ◽  
The Matrix ◽  
Straight Fiber

In this paper, the experimental investigation into the enhancement of mechanical strength in shape memory alloy (SMA) fiber composites is made by using knotted fiber at the two ends instead of straight fiber. TiNi SMA fiber with both ends knotted is used for purpose of better ensuring stress transfer from the matrix to the fiber than straight fiber. Tension test is carried out above the austenitic finish temperature in air. Specimens are heated by means of electrical resistive lamplight heating. The results indicate that the mechanical strength is larger in the knotted fiber composite than in the straight fiber composite. Knotted fiber exerts the superiority of TiNi SMA fiber composite.

The Effect of Debonding Angle on the Reduction of Effective Moduli of Particle and Fiber-Reinforced Composites

2002 ◽  
Vol 69 (3) ◽  
pp. 292-302 ◽  
Author(s):  
Y. H. Zhao ◽  
G. J. Weng
Keyword(s):  
Transversely Isotropic ◽  
Fiber Composites ◽  
Fiber Reinforced Composites ◽  
Anisotropic Damage ◽  
Reinforced Composites ◽  
Effective Moduli ◽  
Loading Mode ◽  
Interfacial Cracks ◽  
The Matrix ◽  
Composite Stiffness

In an effort to uncover the effect of interfacial partial debonding on the reduction of composite stiffness, a reduced moduli approach is proposed for the fictitious inclusions which are used to replace the original partially debonded inclusions. The fictitious inclusions are now perfectly bonded to the matrix and any micromechanical theory can be called upon to estimate the moduli of the composite. Using the volume of the inclusion directly beneath the interfacial cracks under the considered loading mode as a measure of damage, a set of anisotropic damage parameters is established in terms of the debonding angle, providing the reduced moduli for the fictitious inclusions. Specific considerations include debonding on the top and bottom of spheres and prolate inclusions, debonding on the lateral surface of spheres and oblate inclusions, and debonding on the top and bottom of circular fibers and elliptic cylinders. The reductions of the five transversely isotropic moduli for the partially debonded particle composites and the nine orthotropic moduli for the partially debonded fiber composites are examined as the debonding angle increases. The theory is also compared with some finite element results, and it suggests that the concept proposed to estimate the reduced moduli of the fictitious inclusions is a viable one.

scholarly journals Toughness analysis of pineapple leaves fiber composite as alternative material for SNI helmet

2019 ◽  
Vol 13 (4) ◽  
pp. 5961-5972
Author(s):  
Bagus Tri Mulyo ◽  
Heri Yudiono
Keyword(s):  
Impact Strength ◽  
Fiber Composite ◽  
Fiber Composites ◽  
National Standard ◽  
Basic Material ◽  
Control Group ◽  
Fiber Volume ◽  
Alternative Material ◽  
The Impact ◽  
Pineapple Leaves

Along with the times utilization of natural fibers composite materials has been developed. The purpose of this research was to know the impact strength of pineapple leaves fiber composites before applied to basic material for Indonesia National Standard (SNI) helmet. Design of this research was true experimental with posttest-only control design, in this research there were two group, namely experimental group (fiber composite) and control group (SNI helmet). Result of this research showed there was improvement about composite strength with addition fibers volume. The value of absorbed energy and the highest impact strength is found in 10% of fiber volume equals 0.5375 Joules and 0.01657/mm2, far above the SNI helmet which only amounted to 0.3125 Joules and 0.00972 J/mm2. For the highest density value is found in 13% of fiber volume equals 1.4525 g/cm3. It can be concluded that pineapple leaves fiber composites can be used as an alternative material for making SNI helmet.

Potential External Strengthening of Reinforced Concrete Beam Using Natural Fiber Composite Plate

2018 ◽  
Vol 878 ◽  
pp. 41-48 ◽  
Author(s):  
Siew Choo Chin ◽  
Foo Sheng Tong ◽  
Shu Ing Doh ◽  
Jolius Gimbun ◽  
Yuen Kei Foo ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Flexural Strength ◽  
Natural Fiber ◽  
Fiber Composite ◽  
Volume Ratio ◽  
Physical And Mechanical Properties ◽  
Composite Plates ◽  
Reinforced Concrete Beam ◽  
Fiber Volume ◽  
External Strengthening

A study has been conducted to investigate the potential use of mengkuang leaves or Pandanus atrocarpus bonded with epoxy resin as external strengthening material for the strengthening of reinforced concrete (RC) beams. Physical and mechanical properties as well as structural properties of the mengkuang leaves-epoxy composite plates (MLECP) were evaluated in this study. Chemical treatment was performed on the dried mengkuang leaves using sodium hydroxide (NaOH) with concentrations of 2%, 5% and 8%. Scanning electron microscope (SEM) and flexural strength tests were conducted on the mengkuang leaves and flexural specimens, respectively. All the beams were tested to failure under four-point loading. Results showed that the flexural strength of the composite with 0.3 fiber volume ratio exhibited the highest flexural strength. Strengthening of RC beam using MLECP managed to increase the beam capacity.

Compression molding of algae fiber and epoxy composites: Modeling of elastic modulus

2016 ◽  
Vol 37 (19) ◽  
pp. 1202-1216 ◽  
Author(s):  
Alejandra Constante ◽  
Selvum Pillay
Keyword(s):  
Fiber Volume Fraction ◽  
Natural Fiber ◽  
Volume Fraction ◽  
Fiber Composite ◽  
Compaction Pressure ◽  
The United States ◽  
Fiber Composites ◽  
Epoxy Composites ◽  
Natural Fiber Composites ◽  
Fiber Volume

The demand for natural fiber composites in the automotive industry in both Europe and the United States has been forecasted to increase in the coming years. The natural fiber composites based on highly commercialized fibers such as flax, hemp, and sisal has grown to become an important sector of polymeric composites. However, little attention has been addressed to expanding natural fiber composites to include new sources of emerging natural reinforcements, such as reclaimed algae fibers, that have a multiple environmental benefits. Not only are extracted algae fibers biodegradable, the reclamation process has the added benefit of restoring health of waterways choked with algae. This study focuses on the processability of algae fiber–epoxy composites. Short fibers, chemically extracted from raw reclaimed algae, were prepared for natural fiber composite products in two ways. First, randomly oriented mats were produced using the wet-laid process to create layered, compression-molded laminates. Second, loose fibers were dispersed directly into the thermoset matrix to produce a bulk molding compound that was further compression molded into composite lamina. The effect of processing variables such as compaction pressure, temperature, and time were addressed. Moreover, the effect of fiber volume fraction ( υf) and fiber form were considered. Enhanced mechanical properties were found when 56% υf algae fiber was used for the compression-molded laminates composite. This variant exhibited an improvement on the flexural and tensile modulus of 70% and 86% when compared to the neat epoxy. However, the volume of porosity on the same variant was 11% due to lack of compression in some of the fibers. The effect of porosity on the theoretical stiffness was estimated by using the Cox–Krenchel model. Furthermore, an empirical exponential model was formulated to characterize the multi-scale effect of compaction pressure on the overall fiber volume fraction, υf.

Effective Medium of Unidirectional Short-Fiber Composites by a Self-Consistent Method

1987 ◽  
Vol 109 (1) ◽  
pp. 64-66
Author(s):  
Seiichi Nomura
Keyword(s):  
Fiber Composite ◽  
Homogeneous Medium ◽  
Fiber Composites ◽  
Short Fiber ◽  
Effective Medium ◽  
Matrix Phase ◽  
Effective Stiffness ◽  
Self Consistent ◽  
The Matrix ◽  
Consistent Method

A new self-consistent method is proposed to calculate the effective stiffness of unidirectional short-fiber composites where each transversely-isotropic short-fibers is embedded in an infinite homogeneous matrix phase. The equilibrium equation for the elastic field in short-fiber composite materials is converted into an integro-differential equation using the Green’s function for a homogeneous medium. The “effective medium” is chosen in such a way that the ensemble averaged strain field for the composite is equal to that of the homogeneous medium that exhibits the same overall response as the composite. The “effective stiffness” and the “effective mass density” are defined as those properties of the effective medium. The obtained expression for the effective stiffness is new and is not symmetrical with the matrix phase and the fiber phase, thus, reflecting the matrix role more properly than previous works which gave symmetrical results. The result is also favorably compared with experimental data.

A Predicted Approach for Determining Effective Constants of Fiber Composite With Graded Interphase

2007 ◽  
Author(s):  
Jianhui Zhao ◽  
Zhiying Ou
Keyword(s):  
Fiber Composite ◽  
Fiber Composites ◽  
Effective Moduli ◽  
Concentric Cylinder ◽  
Shear Moduli ◽  
Surrounding Matrix ◽  
Mechanics Of Materials ◽  
Special Case ◽  
Force Equilibrium ◽  
Effective Constants

A predicted approach for determining moduli, which include extensional moduli, shear moduli and Poisson’s ratio is presented for fiber composites with graded interphase. The approach is derived based on a mechanics of materials formulations for the concentric cylinder assembles model of a single fiber, surrounding matrix, and a graded interphase to account for the chemical reaction and diffuseness which commonly occurs between fiber and matrix. The principles of the displacement compatibility and force equilibrium for each constitutes of the representative volume element, converted to those of Equivalent Square assembles, are used in the process of the derived predicted approach without complicated computations. The validity of the predicted approach is demonstrated versus comparisons with experimental data and some other models existing in the literature. Synchronously, it shows that determining effective moduli of fiber composite with graded interphase by micromechanics equations is a special case of the predicted approach.

2013 Timoshenko Medal Award Paper—Completion and Closure on Failure Criteria for Unidirectional Fiber Composite Materials

2013 ◽  
Vol 81 (1) ◽  
Author(s):  
Richard M. Christensen
Keyword(s):  
Composite Materials ◽  
Fiber Composite ◽  
Failure Criteria ◽  
Fiber Composites ◽  
Polynomial Invariants ◽  
Unidirectional Fiber ◽  
Detailed Evaluation ◽  
Unidirectional Fiber Composite ◽  
Failure Properties ◽  
Fiber Composite Materials

Building upon previous work, the failure criterion for unidirectional fiber composite materials is examined using a sensitivity analysis as applied to its transverse, matrix controlled failure properties. A new and general relationship is found between these three properties thereby reducing the total number of independent properties needed to calibrate the theory to five. This completes and closes the development of failure criteria for unidirectional fiber composites by the polynomial invariants method. A broad but detailed evaluation of the resulting failure criteria is given. Future applications for these new failure criteria are discussed.

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