scholarly journals Prediction and Measurement of the Damping Ratios of Laminated Polymer Composite Plates

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3370
Author(s):  
Hugo Sol ◽  
Hubert Rahier ◽  
Jun Gu
Keyword(s):  
Material Properties ◽  
Single Layer ◽  
Composite Plates ◽  
Laminated Plates ◽  
Secondary Importance ◽  
Reinforced Composite ◽  
Composites Materials ◽  
Modal Damping ◽  
Resonance Frequencies ◽  
Subsequent Step

Laminated composites materials are mostly used in dynamically loaded structures. The design of these structures with finite element packages is focused on vibrations, elastic deformations and failure control. Damping is often neglected because of its assumed secondary importance and also because of dearth of information on relevant material properties. This trend is prone to change as it is now realised that damping plays an increasingly important role in vibration comfort, noise radiation and crash simulations. This paper shows in a first step how to identify the orthotropic elastic and damping properties of single layer fibre-reinforced composite material sheets using a new extended version of the Resonalyser procedure. The procedure is based on the elastic-viscoelastic correspondence principle and uses a mixed numerical experimental method. In a subsequent step, the complex laminate stiffness values are computed using the identified single layer material properties. To validate this approach, the modal damping ratios of arbitrary laminated plates of different materials at several resonance frequencies are predicted and experimentally verified.

Eigen Value Analysis of Glass Fiber Reinforced Composite Plate

2012 ◽  
Vol 488-489 ◽  
pp. 676-680
Author(s):  
Pramod Kumar ◽  
S.K. Tiwari
Keyword(s):  
Finite Element ◽  
Frequency Response ◽  
Composite Plate ◽  
Composite Plates ◽  
Laminated Plates ◽  
Fiber Reinforced ◽  
Fiber Reinforced Composite ◽  
Advanced Composite ◽  
Reinforced Composite ◽  
Quadrilateral Finite Element

Finite element analysis has been used to find out eigen values and mode shape for fiber reinforced composite plates. FRC plates are important structural elements in modern engineering structures. Vibrations of laminated composite plates have been the subject of significant research activities in recent years. Last two decades have witnessed continued development of advanced composite and other high performance aerospace materials with increased specific strength and modulus, longer fatigue life, higher combat survivability etc. Advanced composite laminates extend the possibility of optimal design through the variation of stacking sequence and fiber orientation, known as composite tailoring. The benefits that accrue from this are not attainable without solving the complexities that are introduced by various coupling effects, such as bending–stretching and bending-twisting. Even, as the matrix material is of relatively low shearing stiffness as compared to the fibers, a reliable prediction of frequency response of laminated plates must account for transverse shear deformation. A four noded quadrilateral finite element is considered for the study of frequency response of composite plate. An analytical solution to the boundary value problem of free vibration response of arbitrarily laminated plates subjected to an admissible boundary condition is presented. A rectangular fiber reinforced composite plate is modeled in FEM software (NISA 15) and natural frequencies, mode shapes are obtained and are compared with the available analytical solutions.

scholarly journals Damping Characteristics of Vibrated Composite Plates

2000 ◽  
Vol 9 (6) ◽  
pp. 096369350000900
Author(s):  
V. Kostopoulos ◽  
D. Th. Korontzis
Keyword(s):  
Plate Thickness ◽  
Composite Plates ◽  
Laminated Plates ◽  
Stability And Convergence ◽  
Mode Shapes ◽  
Damping Characteristics ◽  
Modal Damping ◽  
Linear Viscoelastic ◽  
Linear Viscoelastic Behaviour ◽  
Free Vibration Response

The free vibration response of [±Θ] ns orthogonal, simply supported (all around) composite laminated plates was studied, assuming linear viscoelastic behaviour of the constitutive lamina material. The problem was solved numerically and the results were verified in the special case of [0]2 n laminate against the analytical solution, which is also provided. Stability and convergence problems were discussed analytically. Eigenfrequency values and modal damping characteristics were calculated for the first nine mode shapes. Furthermore, keeping constant the plate thickness, the effect of the lamina thickness on the vibration characteristics of the plate was examined.

Time delay comb transducers for aircraft inspection

2009 ◽  
Vol 113 (1144) ◽  
pp. 417-427 ◽  
Author(s):  
F. Yan ◽  
J. L. Rose
Keyword(s):  
Time Delay ◽  
Material Properties ◽  
Poynting Vector ◽  
Composite Plates ◽  
Guided Wave ◽  
Plate Structures ◽  
Reinforced Composite ◽  
Ultrasonic Guided Wave ◽  
Wave Technique ◽  
Skew Angles

Abstract An ultrasonic guided wave technique based on time delay comb transducers is introduced for aircraft inspection. It is demonstrated that for isotropic plate structures the time delay comb transducers with appropriate excitation are capable of performing discontinuity detections without knowing the precise isotropic material properties of the objects being inspected. Fibre-reinforced composite plates are also considered. The wave skew effects are investigated using both the slowness curve and the Poynting vector. A composite inspection technique that takes advantage of the skew effects is proposed. Using time delay comb transducers to excite the guided wave modes with different skew angles, the proposed technique is capable of scanning the composite plate in different directions without moving or rotating the transducers. By contrast with the applications in the isotropic cases, knowledge of the material properties and other necessary information that is needed to produce dispersion curves is generally required. Experimental results are provided as a validation of the proposed techniques.

Stochastic Finite Element Buckling Analysis of Laminated Plates With Circular Cutout Under Uniaxial Compression

2006 ◽  
Vol 74 (4) ◽  
pp. 798-809 ◽  
Author(s):  
A. K. Onkar ◽  
C. S. Upadhyay ◽  
D. Yadav
Keyword(s):  
Material Properties ◽  
Perturbation Technique ◽  
Compressive Loading ◽  
Laminated Composite ◽  
Composite Plates ◽  
Buckling Analysis ◽  
Laminated Plates ◽  
Buckling Strength ◽  
The Mean ◽  
Random Material Properties

A generalized stochastic buckling analysis of laminated composite plates, with and without centrally located circular cutouts having random material properties, is presented under uniaxial compressive loading. In this analysis, the layerwise plate model is used to solve both prebuckling and buckling problems. The stochastic analysis is done based on mean centered first-order perturbation technique. The mean buckling strength of composite plates is validated with results available in the literature. It has been observed that the present analysis can predict buckling load accurately even for plates with large cutouts. Micromechanics based approach is used to study the effect of variation in microlevel constituents on the effective macrolevel properties like elastic moduli. Consequently, the effect of uncertainty in these material properties on the buckling strength of the laminated plates is studied. Parametric studies are carried out to see the effect of hole size, layups, and boundary conditions on the mean and variance of plate buckling strength.

Development of hybrid layered structures based on natural fabric reinforced composites and warp knitted spacer fabric for acoustic applications

2021 ◽  
pp. 152808372199467
Author(s):  
Nazan Okur ◽  
Mustafa Cagatay Yaradanakul
Keyword(s):  
Sound Absorption ◽  
Single Layer ◽  
Composite Plates ◽  
Layered Structures ◽  
Woven Fabrics ◽  
Double Layers ◽  
Reinforced Composites ◽  
Reinforced Composite ◽  
Spacer Fabric ◽  
Overall Evaluation

This study deals with the development of hybrid layered structures combining natural fabric reinforced composite plates and warp knitted spacer fabric for acoustic applications, and the evaluation of the sound absorption performances. Vacuum infusion technique was used to produce the composite plates. Jute and linen woven fabrics were used as reinforcing materials, and they were impregnated with epoxy resin. The composite plates were combined with warp knitted spacer fabric in different stacking sequences in three-layer structures. All samples were subjected to the measurement of sound absorption property using impedance tube method. The combinations of a single layer and double layers of warp knitted spacer fabric with natural fabric reinforced composite in the appropriate sequences were found to provide superior sound absorption coefficients (SAC) compared to non-hybrid layered structures. Based on the overall evaluation regarding SAC, noise reduction coefficient (NRC), and weight of the structure, the sample with the best performance was regarded as the double layers of spacer fabric backed with a jute fabric reinforced composite plate. The integration of natural fabric reinforced composites with warp knitted spacer fabric had better sound absorption performance compared to the glass fabric reinforced composites, and they were considered to have the potential of being used in interior noise control mainly in vehicles and buildings.

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.

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