• Structural Engineering and Mechanics
• /
• 제44권2호
• /
• pp.127-138
• /
• 2012

The composite materials may be exposed to environmental (thermal or hygral or both) condition during their service life. The effect of environmental condition is usually adverse from the point of view of design of composite structures. In the present research study the effect of hygrothermal condition on the design of laminated composite structures is investigated. The active fiber composite (AFC) which may be utilized as actuator or sensor is considered in the present analysis. The sensor layer is used to sense the level of response of the composite structures. The sensed voltage is fed back to the actuator through the controller. In this study both displacement and velocity feedback controllers are employed to reduce the response of the composite laminate within acceptable limit. The Newmark direct time integration scheme is employed along with modal superposition method to improve the computational efficiency. It is observed from the numerical study that the laminated composite structures become weak in the presence of hygrothermal load. The response of the structure can be brought to the acceptable level once the AFC layer is activated through the feedback loop.

• Smart Structures and Systems
• /
• 제19권6호
• /
• pp.695-703
• /
• 2017

In this paper, based on first-order shear deformation theory, the governing equations of motion for a sandwich curved beam including an elastic core and two piezo-magnetic face-sheets are presented. The curved beam model is resting on Pasternak's foundation and subjected to applied electric and magnetic potentials on the piezo-magnetic face-sheets and transverse loading. The five equations of motion are analytically solved and the bending and vibration results are obtained. The influence of important parameters of the model such as direct and shear parameters of foundation and applied electric and magnetic potentials are studied on the electro-mechanical responses of the problem. A comparison with literatures was performed to validate our formulation and results.

• International journal of advanced smart convergence
• /
• 제9권3호
• /
• pp.97-104
• /
• 2020

In this paper, we propose a method to derive the kernel function directly from the measured apparent earth resistivity. At this time, the kernel function is obtained through the process of solving a nonlinear system. Nonlinear systems with many variables are difficult to solve. This paper also introduces a method for converting nonlinear derived systems to linear systems. The kernel function is a function of the depth and resistance of the Earth's layer. Being able to derive an accurate kernel function means that we can estimate the earth parameters i.e. layer depth and resistivity. We also use various Earth models as simulation examples to validate the proposed method.

• Smart Structures and Systems
• /
• 제15권6호
• /
• pp.1503-1520
• /
• 2015

This paper provides a novel solution for thick-walled cylinders made of functionally graded materials (FGMs). In the formulation, the cylinder is divided into N layers. On the individual layer, the Young's modulus is assumed to be a constant. For an individual layer, two undetermined constants are involved in the elastic solution. Those undetermined coefficients can be evaluated from the continuation condition along interfaces of layers and the boundary conditions at the inner surface and outer surface of cylinder. Finally, the solution for thick-walled cylinders made of functionally graded materials is obtainable. This paper provides several numerical examples which are useful for engineer to design a cylinder made of FGMs.

• 한국소음진동공학회논문집
• /
• 제11권4호
• /
• pp.37-42
• /
• 2001

Active vibration control of laminated composite plates has been carried out to design structure with maximum possible damping capacity, using piezoceramic sensor/actuators and passive constrained-layer damping treatment. The equations of motion are derived for symmetrical, multi-layer laminated plates. The damping ratio(ζ) and modal damping(2ζ$\omega$) of the first bending and torsional modes are calculated by means of iterative complex eigensolution method for both passive and active vibration control. This paper addresses a design strategy of laminated composite plate under structural vibrations.

• Steel and Composite Structures
• /
• 제19권3호
• /
• pp.759-776
• /
• 2015

The First Order Shear Deformation Theory (FOSDT) is considered to study the dynamic behavior of a bimorph beam. A delamination zone between the upper and the lower layer has been taken into consideration; the beam is discretised using the finite elements method (FEM). Several parameters are taken into consideration like structural damping, the geometry, the load nature and the configurations of the boundary conditions. Results show that the delamination between the upper and the lower layer affects considerably the actuation.

• IEIE Transactions on Smart Processing and Computing
• /
• 제4권6호
• /
• pp.443-449
• /
• 2015

This paper considers the physical layer security problem for a two-way vehicle-to-vehicle network, where the two source vehicles can only exchange information through an untrusted relay vehicle. The relay vehicle helps the two-way transmission but also acts as a potential eavesdropper. Each vehicle has a random velocity. By exploiting the random carrier frequency offsets (CFOs) caused by random motions, a secure double-differential two-way relay scheme is proposed. While achieving successful two-way transmission for the source vehicles, the proposed scheme guarantees a high decoding error floor at the untrusted relay vehicle. Average symbol error rate (SER) performance for the source vehicles and the untrusted relay vehicle is analyzed. Simulation results are provided to verify the proposed scheme.

• 대한임베디드공학회논문지
• /
• 제3권1호
• /
• pp.30-33
• /
• 2008

This paper persents how to port HAL (Handset Abstraction Layer) on embedded Linux to support WIPI (Wireless Internet Platform for Interoperability). As smart phones are widespread nowdays, the operating system is changing from a simple kernel like Qualcomm REX OS to more feature-rich Linux kernel. For this reason, we investigate the internal structure of HAL on REX OS and design how to port it to embedded Linux. Careful analysis leads us to identify several porting issues such as thread support, graphical user interface. In addition, we describe some problems discovered during the implementation process and propose alternative architecture of HAL for WIPI on Linux.

• Smart Structures and Systems
• /
• 제22권6호
• /
• pp.743-751
• /
• 2018

In this project, buckling response of polymeric plates reinforced with carbon nanotubes (CNTs) and coated by magnetostrictive layer was studied. The equivalent nanocomposite properties are determined using Mori-Tanak model considering agglomeration effects. The structure is simulated with first order shear deformation theory (FSDT). Employing strains-displacements, stress-strain, the energy equations of the structure are obtained. Using Hamilton's principal, the governing equations are derived considering the coupling of mechanical displacements and magnetic field. Using Navier method, the buckling load of the sandwich structure is obtained. The influences of volume percent and agglomeration of CNTs, geometrical parameters and magnetic field on the buckling load are investigated. Results show that with increasing volume percent of CNTs, the buckling load increases. In addition, applying magnetic field, increases the frequency of the sandwich structure.

• Smart Structures and Systems
• /
• 제29권6호
• /
• pp.767-775
• /
• 2022

Metal additive manufacturing (AM), also known as metal three-dimensional (3D) printing, produces 3D metal products by repeatedly adding and solidifying metal materials layer by layer. During the metal AM process, products experience repeated local melting and cooling using a laser or electron beam, resulting in product defects, such as warpage, cracks, and internal pores. Such defects adversely affect the final product. This paper proposes the in situ monitoring-based warpage prediction of metal AM products with experimental feature extraction. The temperature profile of the metal AM substrate during the process was experimentally collected. Time-domain features were extracted from the temperature profile, and their relationships to the warpage mechanism were investigated. The standard deviation showed a significant linear correlation with warpage. The findings from this study are expected to contribute to optimizing process parameters for metal AM warpage reduction.