Smart Structure

Nonlinear dynamic analysis of dragonfly inspired piezoelectric unimorph actuated flapping and twisting wing

by Ranjan Ganguli

Sujoy Mukherjee & Ranjan Ganguli (2012): Nonlinear dynamic analysis of
dragonfly-inspired piezoelectric unimorph actuated flapping and twisting wing, International Journal of Smart and Nano Materials, DOI:10.1080/19475411.2011.649804

The nonlinear equations for coupled elastic flapping–twisting motion of a dragonfly-inspired smart flapping wing are... more The nonlinear equations for coupled elastic flapping–twisting motion of a dragonfly-inspired smart flapping wing are used for a flapping wing actuated from the root by a PZT unimorph in the piezofan configuration. Excitation by the piezoelectric harmonic force generates only the flap bending motion, which, in turn, induces the
elastic twist motion due to interaction between flexural and torsional vibration modes. An unsteady aerodynamic model is used to obtain the aerodynamic forces. Numerical simulations are performed using a wing whose size is the same as the dragonfly Sympetrum frequens wing. It is found that the value of average lift reaches its maximum when the smart flapping wing is excited at a frequency closer to the natural frequency in torsion. Moreover, consideration of the elastic twisting of the flapping wing leads to an increase in the lift force. It is also found that the flapping wing generates sufficient
lift to support its own weight and carry a small payload. Therefore, the piezoelectrically actuated smart flapping wing based on the geometry of a Sympetrum frequens wing and undergoing flapping–twisting motions can be considered as a potential candidate for use in micro air vehicle applications.

Proposed Configurations for the Use of Smart Dampers with Bracings in Tall Buildings

by Aly Mousaad Aly Sayed Ahmed

Aly Mousaad Aly Sayed Ahmed, Alberto Zasso and Ferruccio Resta

Smart Materials Research
Volume 2012 (2012), Article ID 251543, 16 pages
doi:10.1155/2012/251543

This paper presents wind-induced response reduction in a very slender building using smart dampers with proposed... more This paper presents wind-induced response reduction in a very slender building using smart dampers with proposed bracings-lever mechanism system. The building presents a case study of an engineered design that is instructive. The paper shows that shear response and flexural response of tall buildings present two very different cases for vibration suppression. Smart dampers are implemented optimally in the building to reduce its response in the lateral directions for both structural safety and occupant comfort concerns. New bracings-lever mechanism configurations are proposed for the dampers to improve their performance. The study shows how the proposed configurations can enable application to flexural response and scenarios where the interstory drift is not enough for dampers to work effectively. In addition, a decentralized bang-bang controller improved the performance of the smart dampers.

Nonlinear aspects of energy dissipation in wood-panel joints

by Sara Casciati

Casciati S. (2007). “Nonlinear aspects of energy dissipation in wood-panel joints”. Earthquake Engineering and Engineering Vibration, 6(3), 259-268. ISSN: 1671-3664.

DATA E LUOGO DI PUBBLICAZIONE: September 2007; Springer, New York, NY 10013, USA.

ABSTRACT: The joints connecting vertical and horizontal elements are the “weak link” in structural systems assembled... more ABSTRACT: The joints connecting vertical and horizontal elements are the “weak link” in structural systems assembled from wood panels. If they are too weak, local failures may occur, resulting in performance that is significantly below expectations. If they are too resistant, the joints may be unable to dissipate energy during vibrations, thus possibly initiating a fast progressive failure. This paper re-processes and re-elaborates the results of shaking table tests previously carried out by the author and other co-workers. The goal is to assess the feasibility of a joint which is able to dissipate energy during vibration, without degrading the connection performance.

KEYWORDS: dynamic excitation - energy dissipation - wood panels joint - monitoring system - shaking table tests

Swarm Intelligence Algorithms for Integrated Optimization of Piezoelectric Actuator and Sensor Placement and Feedback Gains

by Ranjan Ganguli

Composite material and piezoelectric coefficient uncertainty effects on structural health monitoring using feedback control gain as damage indicators

by Ranjan Ganguli

Nonlinear Dynamic Analysis of a Piezoelectrically Actuated Flapping Wing

by Ranjan Ganguli

A Dragonfly Inspired Flapping Wing Actuated by Electroactive Polymers

by Ranjan Ganguli

Influence of Temperature and High Electric Field on Power Consumption by Piezoelectric Actuated Integrated Structure

by Ranjan Ganguli

Optimal Placement of Piezoelectric Actuated Trailing-Edge Flaps for Helicopter Vibration Control

by Ranjan Ganguli

Experimental Demonstration of H-Infinity based Vibration Suppression in Composite Fin Tip of Aircraft using Optimally Placed Piezoelectric Flap Actuators

by Ranjan Ganguli

Single Crystal Piezoceramics for Dynamic Stall Suppression

by Ranjan Ganguli

Effect of Piezoelectric Hysteresis on Helicopter Vibration Control Using Trailing-Edge Flaps

by Ranjan Ganguli

Analytical and Experimental Comparisons of Electromechanical Vibration Response of a Piezoelectric Bimorph Beam for Power Harvesting

by Mikail Lumentut

Special Issue (In Press)

The analysis of a piezoelectric bimorph beam with two input base motions for power harvesting

by Mikail Lumentut

Analytical Modelling of Self-Powered Electromechanical Piezoelectric Bimorph Beams with Multidirectional Excitation

by Mikail Lumentut