• Journal of Korean Association for Spatial Structures
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• v.1 no.1 s.1
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• pp.109-115
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• 2001

Composite materials also known as fiber reinforced plastics have been developed and used in many engineering applications due to their outstanding mechanical properties. Laminated plates as structural components that are made of in composite material are widely used. Therefore, nonlinear response of laminated composite plates modeled with finite elements and excited by stochastic loading is studied. The classical laminated plate theory is used to account for the variation of strains through the thickness for modeling laminated thin plates. Approximate nonlinear random vibration analysis is performed using the method of equivalent linearization to account for material non-linearity.

• Advances in Computational Design
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• v.2 no.1
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• pp.57-69
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• 2017

The composite plate to upgrade structures and, in particular, to extend the lives of reinforced concrete beams has wide applications. One of the main aspects of the bonded strengthening technology is the stress analysis of the reinforced structure. In particular, reliable evaluation of the adhesive shear stress and of the stress in the composite plates is mandatory in order to predict the beam's failure load. In this paper, a finite element analysis is presented to calculate the stresses in the reinforced beam under mechanical loads. The numerical results was compared with the analytical approach, and a parametric study was carried out to show how the maximum stresses have been influenced by the material and geometry parameters of the composite beam.

• International Journal of Aeronautical and Space Sciences
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• v.11 no.3
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• pp.227-233
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• 2010

In this study, a genetic algorithm was utilized to optimize the stacking sequence of a composite plate subjected to a high velocity impact. The aim is to minimize the maximum backplane displacement of the plate. In the finite element model, we idealized the impactor using solid elements and modeled the composite plate by shell elements to reduce the analysis time. Various tests were carried out to investigate the effect of parameters in the genetic algorithm such as the type of variables, population size, number of discrete variables, and mutation probability.

• Structural Monitoring and Maintenance
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• v.1 no.4
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• pp.411-425
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• 2014

A relatively low frequency Lamb wave-based damage identification method called damage imaging method for rectangular composite plate is presented. A damage index (DI) is generated from the delay matrix of the Lamb wave response signals, and it is used to indicate the location and approximate area of the damage. The viability of this method is demonstrated by analyzing the numerical and experimental Lamb wave response signals from rectangular composite plates. The technique only requires the response signals from the plate after damage, and it is capable of performing near real time damage identification. This study sheds some light on the application of Lamb wave-based damage detection algorithm for plate-type structures by using the relatively low frequency (e.g., in the neighborhood of 100 kHz, more suitable for the best capability of the existing fiber optic sensor interrogator system with the sampling frequency of 500 kHz) Lamb wave response and a reference-free damage detection technique.

• Journal of the Korean Society for Nondestructive Testing
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• v.9 no.2
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• pp.25-36
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• 1989

This essay is a general review of the application of ultrasonic NDE techniques to the performance assessment and characterization of composite materials. A brief review of ultrasonic input-output characterization of a composite plate by shear waves is presented. A theoretical development of ultrasonic wave propagation in isotropic and anisotropic media excited, respectively, by a circular transducer and an oscillatory point source is summarized. Some experimental results are described in which ultrasonic velocity and attenuation measurements give insight into material degradation of fatigued composite laminates. Ultrasonic determination of the elastic constants of a composite plate and an experimental attempt at ultrasonic testing of an isotropic plate containing a crack are also included. A recent effort for the characterization of viscoelastic materials using the ultrasonic NDE technique is outlined. Finally, the reliability of ultrasonic NDE is briefly touched upon.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.681-688
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• 2011

Structural model of laminated composite plates based on the first order shear deformable plate theory and subjected to a combination of magnetic and thermal fields is developed. Coupled equations of motion are derived via Hamilton's principle on the basis of electromagnetic equations (Faraday, Ampere, Ohm, and Lorenz equations) and thermal equations which are involved in constitutive equations. In order to obtain the implications of a number of geometrical and physical features of the model, one special case is investigated, that is, free vibration of a composite plate immersed in a transversal magnetic field. Special coupling effects between the magnetic and elastic fields are revealed in this paper.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.3
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• pp.220-228
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• 1997

We discuss finite element approximation and use a Mindlin plate element based upon uniformly reduced numerical integration. The finite element selected for use in this work is a four-node, bilinear displacement element based upon the Mindlin theory of plates. Such elements show good accuracy for laminated composite plates when reduced numerical integration is used to evaluate the element marices. This study presents both the experimental and F.E. results for the natural frequencies of CFRPURETHANE-CFRP Composite plate. Good agreement between experimental and calculated frequencies is achived.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.250-253
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• 2004

Emphasis has been placed on thin plate fabrication of plain woven carbon fabric reinforced Al matrix composites using liquid pressing process. The composite has potential applications for PDP rear plate. The process is to use the low pressure for infiltration of Al melt into plain woven carbon fabric as the Al melt is pressurized directly. The minimum pressure required for the infiltration was calculated from force balance equation, permeability measurements and compaction behavior of carbon fiber. Also, the melting temperature and the holding time have been optimized. In order to measure coefficient of thermal expansion (CTE) of the composites, the thermal strain measurement using strain gage was performed and the thermal conductivity of the composites was measured using laser flash method. The constituent materials of the composite are PAN type carbon fibers as reinforcements and 6061 Al alloys as matrices.

• Steel and Composite Structures
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• v.33 no.4
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• pp.551-568
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• 2019

This proposed project presents the bi-axial and uni-axial stability behavior of laminated composite plates based on an original three variable "refined" plate theory. The important "novelty" of this theory is that besides the inclusion of a cubic distribution of transverse shear deformations across the thickness of the structure, it treats only three variables such as conventional plate theory (CPT) instead five as in the well-known theory of "first shear deformation" (FSDT) and theory of "higher order shear deformation" (HSDT). A "shear correction coefficient" is therefore not employed in the current formulation. The computed results are compared with those of the CPT, FSDT and exact 3D elasticity theory. Good agreement is demonstrated and proved for the present results with those of "HSDT" and elasticity theory.

• Smart Structures and Systems
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• v.30 no.4
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• pp.371-383
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• 2022

A novel impact localization method is presented based on impact induced elastic waves in sensorized composite structure subjected to temperature fluctuations. In real practices, environmental and operational conditions influence the acquired signals and consequently make the feature (particularly Time of Arrival (TOA)) extraction process, complicated and troublesome. To overcome this complication, a robust TOA estimation method is proposed based on the times in which the absolute amplitude of the signal reaches to a specific amplitude value. The presented method requires prior knowledge about the normalized wave velocity in different directions of propagation. To this aim, a finite element model of the plate was built in ABAQUS/CAE. The impact location is then highlighted by calculating an error value at different points of the structure. The efficiency of the developed impact localization technique is experimentally evaluated by dropping steel balls with different energies on a carbon fiber composite plate with different temperatures. It is demonstrated that the developed technique is able to localize impacts with different energies even in the presence of noise and temperature fluctuations.