• Smart Structures and Systems
• /
• 제12권2호
• /
• pp.121-136
• /
• 2013

This study proposes an innovative control approach to suppress the responses of a beam structural system under moving forces. The proposed control algorithm is a synthesis of the adaptive input estimation method (AIEM) and linear quadratic Gaussian (LQG) controller. Using the synthesis algorithm the moving forces can be estimated using AIEM while the LQG controller offers proper control forces to effectively suppress the beam structural system responses. Active control numerical simulations of the beam structural system are performed to evaluate the feasibility and effectiveness of the proposed control technique. The numerical simulation results show that the proposed method has more robust active control performance than the conventional LQG method.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 하계학술대회 논문집 D
• /
• pp.2073-2075
• /
• 2003

This paper presents the active vibration control of flexible cantilever beam using piezoceramic actuators. The transfer function from the force input to the bending displacement was obtained via modal analysis results and piezoelectric constitutive equations. For the active vibration control piezoceramic actuators and sensors were used to construct a flexible smart cantilever beam. To further enhance the sensing and actuation properties of the piezoceramics, a typical interdigitated electrode pattern was fabricated. The PID controller was designed via various simulation and experiment trials. It was shown that the PID controller could suppress vibration of the beam effectively. Simulations and experiments verified good performances of the designed controller.

• Steel and Composite Structures
• /
• 제18권5호
• /
• pp.1119-1127
• /
• 2015

A finite-element model for beams with partially delaminated layers is used to investigate their behavior. In this formulation account is taken of lateral strains and the first-order shear deformation theory is used. Both displacement continuity and force equilibrium conditions are imposed between the regions with and without delamination. Numerical results of the present model are presented and its performance is evaluated for static and dynamic problems.

• Advances in materials Research
• /
• 제8권3호
• /
• pp.237-257
• /
• 2019

The present article researches large-amplitude thermal free vibration characteristics of nonlocal two-phase piezo-magnetic nano-size beams having geometric imperfections by considering piezoelectric reinforcement scheme. The piezoelectric reinforcement can cause an enhanced vibration behavior of smart nanobeams under magnetic field. All previous studies on vibrations of piezoelectric-magnetic nano-size beams ignore the influences of geometric imperfections which are crucial since a nanobeam is not always ideal or perfect. Nonlinear governing equations of a smart nanobeam are derived based on classical beam theory and an analytical trend is provided to obtain nonlinear vibration frequency. This research shows that changing the volume fraction of piezoelectric phase in the material has a great influence on vibration behavior of smart nanobeam under electric and magnetic fields. Also, it can be seen that nonlinear vibration behaviors of smart nanobeam is dependent on the magnitude of exerted electric voltage, magnetic imperfection amplitude and substrate constants.

• Smart Structures and Systems
• /
• 제25권1호
• /
• pp.37-45
• /
• 2020

This paper aims at enlightening the properties, computational and implementation issues related to Kalman filter based state estimation algorithms and sliding mode observers, by applying them for estimating the states of a smart structure system. The Kalman based estimators considered in this work are Kalman filter and information filter and, the sliding mode observers considered are Utkin observer and higher order sliding mode observer. A fourth order linear time invariant model of a piezo actuated beam is used in this work. This structure is embedded with four number of piezo patches, of which two act as sensors, one as disturbance actuator and the other as control actuator. The performance of the state estimation algorithms is evaluated through simulation, for the first two vibrating modes of the piezo actuated structure, when the structure is maintained at first mode and second mode resonance.

• Smart Structures and Systems
• /
• 제18권6호
• /
• pp.1125-1143
• /
• 2016

Forced vibration analysis of a simple supported viscoelastic nanobeam is studied based on modified couple stress theory (MCST). The nanobeam is excited by a transverse triangular force impulse modulated by a harmonic motion. The elastic medium is considered as Winkler-Pasternak elastic foundation.The damping effect is considered by using the Kelvin-Voigt viscoelastic model. The inclusion of an additional material parameter enables the new beam model to capture the size effect. The new non-classical beam model reduces to the classical beam model when the length scale parameter is set to zero. The considered problem is investigated within the Timoshenko beam theory by using finite element method. The effects of the transverse shear deformation and rotary inertia are included according to the Timoshenko beam theory. The obtained system of differential equations is reduced to a linear algebraic equation system and solved in the time domain by using Newmark average acceleration method. Numerical results are presented to investigate the influences the material length scale parameter, the parameter of the elastic medium and aspect ratio on the dynamic response of the nanobeam. Also, the difference between the classical beam theory (CBT) and modified couple stress theory is investigated for forced vibration responses of nanobeams.

• Smart Structures and Systems
• /
• 제19권4호
• /
• pp.393-402
• /
• 2017

Many vibration-based global damage detection methods attempt to extract modal parameters from vibration signals as the main structural features to detect damage. The local flexibility method is one promising method that requires only the first few fundamental modes to detect not only the location but also the extent of damage. Generally, the mode shapes in the lateral degree of freedom are extracted from lateral vibration signals and then used to detect damage for a beam structure. In this study, a new approach which employs the mode shapes in the rotary degree of freedom obtained from the macro-strain vibration signals to detect damage of a beam structure is proposed. In order to facilitate the application of mode shapes in the rotary degree of freedom for beam structures, the local flexibility method is modified and utilized. The proposed rotary approach is verified by numerical and experimental studies of simply supported beams. The results illustrate potential feasibility of the proposed new idea. Compared to the method that uses lateral measurements, the proposed rotary approach seems more robust to noise in the numerical cases considered. The sensor configuration could also be more flexible and customized for a beam structure. Primarily, the proposed approach seems more sensitive to damage when the damage is close to the supports of simply supported beams.

• Smart Structures and Systems
• /
• 제15권5호
• /
• pp.1233-1252
• /
• 2015

This study investigates the problem of crack detection in post-buckled beam-type structures. The beam under the axial compressive force has a crack, assumed to be open and through the width. The crack, which is modeled by a massless rotational spring, divides the beam into two segments. The crack detection is considered as an optimization problem, and the weighted sum of the squared errors between the measured and computed natural frequencies is minimized by the bees algorithm. To find the natural frequencies, the governing nonlinear equations of motion for the post-buckled state are first derived. The solution of the nonlinear differential equations of the two segments consists of static and dynamic parts. The differential quadrature method along with an arc length strategy is used to solve the static part, while the same method is utilized for the solution of the linearized dynamic part and the extraction of the natural frequencies of the cracked beam. The investigation includes several numerical as well as experimental case studies on the post-buckled simply supported and clamped-clamped beams having open cracks. The results show that several parameters such as the amount of applied compressive force and boundary conditions influences the outcome of the crack detection scheme. The identification results also show that the crack position and depth can be predicted well by the presented method.

• Advances in nano research
• /
• 제17권3호
• /
• pp.285-291
• /
• 2024

The paper considers one of the new applications of computer methods in music composition, using smart nanobeams-an integration of advanced computational techniques with new, specially designed materials for enhanced performance capabilities in music composition. The research applies some peculiar properties of smart nanobeams, embedded with piezoelectric materials that modulate and control sound vibrations in real-time. The study is conducted to determine the effects of changes in the length, thickness of nanobeams and the applied voltage on acoustical properties and the tone quality of musical instruments with the help of numerical simulations and optimization algorithms. By means of piezo-elasticity theory, different governing equations of nanobeam systems can be derived, which are solved by the numerical method to predict the dynamic behavior of the system under different conditions. Results show that manipulation of the parameters allows great control over pitch, timbre, and resonance of the instrument; such a system offers new ways in which composers and performers can create music. This research also validates the computational model against available theoretical data, proving the accuracy and possible applications of the former. The work thus marks a large step towards the intersection of music composition with smart material technology, and, when further developed, it would mean that smart nanobeams could revolutionize the process for composing and performing music on these instruments.

• Structural Engineering and Mechanics
• /
• 제55권4호
• /
• pp.765-784
• /
• 2015

Connections are usually designed either as pinned usually associated with simple construction or rigid normally is associated with continuous construction. However, the actual behaviour falls in between these two extreme cases. The use of partial strength or semi-rigid connections has been encouraged by Euro-code 3 and studies on semi-continuous construction have shown substantial savings in steel weight of the overall construction. Composite connections are proposed in this paper as partial or full strength connections. Standardized connection tables are developed based on checking on all possible failure modes as suggested by "component method" for beam-to-column composite connection on major axis. Four experimental tests were carried out to validate the proposed standardised connection table. The test results showed good agreement between experimental and theoretical values with the ratio in the range between 1.06 to 1.50. All tested specimens of the composite connections showed ductile type of failure with the formation of cracks occurred on concrete slab at maximum load. No failure occurred on the Trapezoidal Web Profiled Steel Section as beam and on the British Section as column.