Dynamics of structures

The Mechanics of Vibration By Prof R E D Bishop and Prof D C Johnson Pp xii + 592 (Cambridge: At the University Press, 1960) 120s net

The Mechanics of Vibration

Wave band gaps in two-dimensional piezoelectric/piezomagnetic phononic crystals

Micromechanical analysis of magneto-electro-thermo-elastic composite materials with applications to multilayered structures

Magneto-electro-elastic (MEE) materials have been receiving a special attention from the research community owing to their specialized performance and coupled behavior under thermal, electric, magnetic and mechanical loads. The possibility of prospective energy conversion means, have additionally been added to the cause of researching about these materials. Therefore, the review presented here may be considered as a topical discussion on MEE materials and structures. Through this paper, all critical concepts revolving around MEE materials are discussed in separate sections ranging from the very definition of MEE materials, their material phenomenon, types and properties, to certain fundamental theories and micromechanical models, structural analyses of MEE structures and their nano-sized counterparts, effects of various external and internal parameters and prospective applications of these materials. The present study is in no ways exhaustive to the methods and results observed, but it may be considered as a guide to researchers and scholars about the behavior of MEE materials, wherein critical observations and analyses’ techniques are discussed.

Computational Analysis of Smart Magneto-Electro-Elastic Materials and Structures: Review and Classification

/pdf/transient-response-of-magneto-electro-elastic-simply-4s7ocjpskz.pdf

Transient response of magneto-electro-elastic simply supported cylinder using finite element

Comparative studies of the transient response for PECP, MSCP, Barium Titanate, magneto-electro-elastic finite cylindrical shell under constant internal pressure using finite element method

This paper presents a multiobjective optimization formulation to detect and quantify crack damage in beam structures at variable locations. It is implemented at the substructure level where the concept is to balance the instantaneous power flow by equating the input power to the dissipated power and the time rate of change of kinetic and strain energies and power transferred to adjacent substructures. This imbalance is reduced to zero to identify the structural parameters or damages. For improved results, the power balance method is combined with conventional acceleration matching method where the objective is to minimize the deviation between measured and estimated accelerations—no additional sensors are required to incorporate the extra power flow balance criteria. Numerical simulations are performed for a lumped mass system, a planar truss structure, and a cantilever beam of 20 elements with multiple damages to evaluate the accuracy of the proposed method. Effects of noise are also taken into account by contaminating the measured responses with 3%, 5%, and 10% Gaussian noise. The particle swarm optimization is used as the optimization algorithm, and normalized fitness functions are defined for both power flow and acceleration components with weighted aggregation multiobjective optimization technique. The effects of various weighting factors for the combined objective function are also studied. The results demonstrate that improvement in accuracy of damage detection is achieved by the combined method, when compared with previous acceleration only matching method as well as other methods. Copyright © 2013 John Wiley & Sons, Ltd.

Damage identification using combined transient power flow balance and acceleration matching technique

This paper presents the application of a power flow parameter to improve system identification results when used along with conventional acceleration matching techniques. In this paper the power balance concept is implemented in a substructure to estimate the stiffness and damping coefficients from time domain responses. Power flows are calculated using the time averaged product of force and velocity at the input and substructure interfaces of a substructure. The concept of power flow balance through the substructures is to equate the input power against the dissipated and transmitted powers and by reducing any imbalance to zero using optimization methods. No extra sensors are needed to include criteria of power flow balance along with acceleration matching. Numerical simulations are performed for substructures from a 10 degree-of-freedom (DOF) lumped mass system, a planar truss of 55 elements with 44 DOF and a cantilever beam of 20 elements to evaluate the feasibility of the proposed method. In numerical simulations, noise free and noise contaminated response measurements are considered. The Particle Swarm approach is used as the Optimization algorithm, and the fitness function is defined to minimize the error with weighted aggregation multi-objective optimization (MO) technique. The results demonstrate that the proposed combined method is more accurate in identifying the structural parameters of a system compared to conventional acceleration based matching methods.

Identification of Structural Parameters Using Combined Power Flow and Acceleration Approach in a Substructure

This article presents a multi-objective optimization (MO) formulation to detect cracks in structures using time-domain acceleration responses combined with power flow balance conditions. No additional sensors are required to ensure power flow balance. This is an application of inverse problem formulation whereby the unknown structural stiffnesses are estimated by minimizing the difference between the measured and theoretically predicted accelerations; simultaneously ensuring the net power flow balance in the substructure is zero. Numerical simulations are performed for identifying a lumped mass system and damage detection in a cantilever beam of 20 elements with single crack. Effects of noise are also taken into account by contaminating the measured responses with up to 5% Gaussian noise. The particle swarm approach is used as the optimization algorithm, and the objective function is defined to minimize the error with weighted contribution of both acceleration and power flow parameters. The effects of var...

K. Shankar

Papers

Transient response of magneto-electro-elastic simply supported cylinder using finite element

Comparative studies of the transient response for PECP, MSCP, Barium Titanate, magneto-electro-elastic finite cylindrical shell under constant internal pressure using finite element method

Damage identification using combined transient power flow balance and acceleration matching technique

Identification of Structural Parameters Using Combined Power Flow and Acceleration Approach in a Substructure

Crack identification using combined power flow and acceleration matching technique