Integrated Damping Mechanics for Thick Composite Laminates and Plates

1994 ◽  
Vol 61 (2) ◽  
pp. 375-383 ◽  
Author(s):  
D. A. Saravanos
Keyword(s):  
Composite Laminates ◽  
Volume Ratio ◽  
Composite Plates ◽  
Displacement Fields ◽  
Fiber Volume ◽  
Modal Damping ◽  
Interlaminar Shear ◽  
Continuous Displacement ◽  
Shear Damping ◽  
Lamination Thickness

A method for predicting the damped dynamic characteristics of thick composite laminates and plates is presented. Unified damping mechanics relate the damping of composite plates to constituent properties, fiber volume ratio, fiber orientation, laminate configuration, plate geometry, temperature, and moisture. Discrete layer damping mechanics for thick laminates, entailing piecewise continuous displacement fields and including the effects of interlaminar shear damping, are described. A semi-analytical method for predicting the modal damping and natural frequencies of thick simply-supported specialty composite plates is included. Applications demonstrate the validity, merit, and ranges of applicability of the new theory. The applications further illustrate the significance of interlaminar shear damping, and investigate the effects of lamination, thickness aspect ratio, fiber content, and temperature.

scholarly journals Chopped Strand/Plain Weave E-Glass as Reinforcement in Vacuum Bagged Epoxy Composites

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Srinivas Shenoy Heckadka ◽  
Suhas Yeshwant Nayak ◽  
Karan Narang ◽  
Kirti Vardhan Pant
Keyword(s):  
Shear Strength ◽  
Composite Laminates ◽  
Polymer Matrix Composites ◽  
Impact Resistance ◽  
Interlaminar Shear Strength ◽  
Fiber Volume ◽  
Glass Composites ◽  
Plain Weave ◽  
Specific Strength ◽  
Interlaminar Shear

Polymer matrix composites are one of the materials being extensively researched and are gaining a lot of importance due to advantages like high specific strength, greater flexibility in design, and reduced cost of manufacturing. In this study, tensile, flexural, impact, and interlaminar shear strength of chopped strand/plain weave E-glass composites were considered. Composite laminates with different stacking sequence were fabricated using Vacuum Assisted Resin Infusion Moulding (VARIM) technique. Fiber volume fractions (FVF) of 22%, 26%, and 30% were adopted. Experiments were conducted in accordance with ASTM standards. Results indicate that laminates with three layers of plain weave mat exhibited better tensile, flexural, and interlaminar shear strength. However, laminates with two layers of chopped strand mat and one layer of plain weave mat showed improved impact resistance. In addition, scanning electron microscopy was used to analyze the fracture surface.

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.

scholarly journals Modal Performance of Two-Fiber Orthogonal Gradient Composite Laminates Embedded with SMA

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1102 ◽  
Author(s):  
Yizhe Huang ◽  
Zhifu Zhang ◽  
Chaopeng Li ◽  
Kuanmin Mao ◽  
Qibai Huang
Keyword(s):  
Composite Laminates ◽  
Volume Fraction ◽  
Plate Theory ◽  
Single Layer ◽  
Composite Plates ◽  
Distribution Model ◽  
Fiber Volume ◽  
Two Phase ◽  
Gradient Distribution ◽  
Component Content

A gradient composite laminate that was composed of two-phase fibers, a shape memory alloy (SMA), and graphite was prepared to investigate modal performance and improve vibration behavior. The stress-strain relation of the single-layer composite plates was derived from Kirchhoff thin plate theory and the material constitutive of the SMA. A gradient distribution model and the eigenvalue equations of gradient composite laminates were developed. The influence of the fiber component content gradient distribution, pre-strain, the two-phase fiber volume fraction, and geometric parameters on the modal performance was analyzed. This study provides a method to avoid the structural resonance of composite laminates that are embedded with an SMA through the gradient distribution of two-phase fiber content that leads to the interaction of the material properties.

Physical Ultrasonics of Composites

2011 ◽  
Author(s):  
Dale Chimenti ◽  
Stanislav Rokhlin ◽  
Peter Nagy
Keyword(s):  
Composite Laminates ◽  
Stiffness Matrix ◽  
Composite Plates ◽  
Anisotropic Media ◽  
Anisotropic Materials ◽  
Ultrasonic Waves ◽  
Laminated Plates ◽  
Structure Characteristic ◽  
Major Advance

Physical Ultrasonics of Composites is a rigorous introduction to the characterization of composite materials by means of ultrasonic waves. Composites are treated here not simply as uniform media, but as inhomogeneous layered anisotropic media with internal structure characteristic of composite laminates. The objective here is to concentrate on exposing the singular behavior of ultrasonic waves as they interact with layered, anisotropic materials, materials which incorporate those structural elements typical of composite laminates. This book provides a synergistic description of both modeling and experimental methods in addressing wave propagation phenomena and composite property measurements. After a brief review of basic composite mechanics, a thorough treatment of ultrasonics in anisotropic media is presented, along with composite characterization methods. The interaction of ultrasonic waves at interfaces of anisotropic materials is discussed, as are guided waves in composite plates and rods. Waves in layered media are developed from the standpoint of the "Stiffness Matrix", a major advance over the conventional, potentially unstable Transfer Matrix approach. Laminated plates are treated both with the stiffness matrix and using Floquet analysis. The important influence on the received electronic signals in ultrasonic materials characterization from transducer geometry and placement are carefully exposed in a dedicated chapter. Ultrasonic wave interactions are especially susceptible to such influences because ultrasonic transducers are seldom more than a dozen or so wavelengths in diameter. The book ends with a chapter devoted to the emerging field of air-coupled ultrasonics. This new technology has come of age with the development of purpose-built transducers and electronics and is finding ever wider applications, particularly in the characterization of composite laminates.

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.

Flexural Response of Inorganic Hybrid Composites With E-Glass and Carbon Fibers

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
James W. Giancaspro ◽  
Christos G. Papakonstantinou ◽  
P. N. Balaguru
Keyword(s):  
Carbon Fibers ◽  
Hybrid Composite ◽  
Composite Laminates ◽  
Hybrid Composites ◽  
Glass Fibers ◽  
Composite Plates ◽  
Carbon Composite ◽  
Primary Objective ◽  
Flexural Capacity ◽  
Compression Failure

By far, carbon and glass fibers are the most popular fiber reinforcements for composites. Traditional carbon composites are relatively expensive since the manufacturing process requires significant heat and pressure, while the carbon fibers themselves are inherently expensive to produce. In addition, they are often flammable and their use is restricted when fire is a critical design parameter. Glass fabrics are approximately one order of magnitude less expensive than similar carbon fabrics. However, they lack the stiffness and the durability needed for many high performance applications. By combining these two types of fibers, hybrid composites can be fabricated that are strong, yet relatively inexpensive to produce. The primary objective of this study was to experimentally investigate the effects of bonding high strength carbon fibers to E-glass composite cores using a high temperature, inorganic matrix known as geopolymer. Carbon fibers were bonded to E-glass cores (i) on only the tension face, (ii) on both the tension and compression faces, or (iii) dispersed throughout the core in alternating layers to obtain a strong, yet economical, hybrid composite laminate. For each response measured (flexural capacity, stiffness, and ductility), at least one hybrid configuration displayed mechanical properties comparable to all carbon composite laminates. The results indicate that hybrid composite plates manufactured using 3k unidirectional carbon tape exhibit increases in flexural capacity of approximately 700% over those manufactured using E-glass fibers alone. In general, as the relative amount of carbon fibers increased, the likelihood of precipitating a compression failure also increased. For 92% of the specimens tested, the threshold for obtaining a compression failure was utilizing 30% carbon fibers. The results presented herein can dictate future studies to optimize hybrid performance and to achieve economical configurations for a given set of design requirements.

Interply Behavior Exhibited in Compliant Filamentary Composite Laminates

1982 ◽  
Vol 55 (4) ◽  
pp. 1078-1094 ◽  
Author(s):  
J. L. Turner ◽  
J. L. Ford
Keyword(s):  
Shear Strain ◽  
Composite Laminates ◽  
Matrix Material ◽  
Matrix Composites ◽  
Efficient Manner ◽  
Strain Behavior ◽  
The Matrix ◽  
Order Of Magnitude ◽  
Extensional Strain ◽  
Interlaminar Shear

Abstract Cord-rubber composite systems allow a visualization of interply shear strain effects because of the compliant nature of the matrix material. A technique termed the pin test was developed to aid this visualization of interply shear strain. The pin test performed on both flat pads and radial tires shows that interlaminar shear strain behavior in both types of specimens is similar, most of the shear strain being confined to a region approximately 10 interly rubber thicknesses from the edge. The observed shear strain is approximately an order of magnitude greater than the applied extensional strain. A simplified mathematical model, called the Kelsey strip, for describing such behavior for a two-ply (±θ) cord-rubber strip has been formulated and demonstrated to be qualitatively correct. Furthermore, this model is capable of predicting trends in both compliant and rigid matrix composites and allows for simplified idealizations. A finite-element code for dealing with such interply effects in a simple but efficient manner predicts qualitatively correct results.

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