Dimitris A. Saravanos

Bio: Dimitris A. Saravanos is an academic researcher from University of Patras. The author has contributed to research in topics: Finite element method & Piezoelectricity. The author has an hindex of 31, co-authored 154 publications receiving 3914 citations. Previous affiliations of Dimitris A. Saravanos include Glenn Research Center & Case Western Reserve University.

Mechanics and Computational Models for Laminated Piezoelectric Beams, Plates, and Shells

Abstract: A considerable number of laminate theories, analytical approaches, numerical solutions and computational models have been reported for the analysis of laminates and structures with piezoelectric actuators or sensors. This article provides a review of published work in this area of mechanics. The reported laminate theories and structural mechanics are classified based on fundamental assumptions, the approximation of the through-the-thickness variation of the electromechanical state variables, the method of representation of piezoelectric layers, and their capability to model curvilinear geometries and thermal effects. The performance, advantages and limitations of the various categories of laminate theories are subsequently assessed by correlating results obtained by representative average models. The capability of each theory to model global structural response, local through-the-thickness variations of electromechanical variables, stresses, and piezoelectric laminates of high thickness is also quantified. This review article includes 103 references.

Exact free‐vibration analysis of laminated plates with embedded piezoelectric layers

Abstract: Exact solutions are developed for predicting the coupled electromechanical vibration characteristics of simply supported laminated piezoelectric plates composed of orthorhombic layers. The three‐dimensional equations of motion and the charge equation are solved using the assumptions of the linear theory of piezoelectricity. The through‐thickness distributions for the displacements and electrostatic potential are functions of eight constants for each layer of the laminate. Enforcing the continuity and surface conditions results in a linear system of equations representing the behavior of the complete laminate. The determinant of this system must be zero at a resonant frequency. The natural frequencies are found numerically by first incrementally stepping through the frequency spectrum and refining the final frequencies using bisection. Representative frequencies and mode shapes are presented for a variety of lamination schemes and aspect ratios.

Coupled layerwise analysis of composite beams with embedded piezoelectric sensors and actuators

Abstract: Unified mechanics are developed with the capability to model both sensory and active composite laminates with embedded piezoelectric layers. Two discretelayer (or layerwise) formulations enable analysis of both global and local electromechanical response. The first assumes constant through-the-thickness displacement, while the second permits piecewise continuous variation. The mechanics include the contributions from elastic, piezoelectric and dielectric components. The incorporation of electric potential into the state variables permits representation of general electromechanical boundary conditions. Approximate finite element solutions for the static and freevibration analysis of beams are presented. Applications on composite beams demonstrate the capability to represent either sensory or active structures, and to model the complicated stressstrain fields, the interactions between passive/active layers and interfacial phenomena between sensors and composite plies. The capability to predict the dynamic c...

Mixed Laminate Theory and Finite Element for Smart Piezoelectric Composite Shell Structures

Abstract: Mechanicsfortheanalysisoflaminatedcompositeshellswithpiezoelectricactuatorsandsensorsarepresented.A newmixedlaminatetheoryforpiezoelectricshellsisdevelopedincurvilinearcoordinatesthatcombinessingle-layer assumptions for the displacements and a layerwise representation for the electric potential. The resultant coupled governing equations for curvilinear piezoelectric laminates are described. Structural mechanics are subsequently developed and an eight-node ® nite element is formulated for the static and dynamic analysis of adaptivecomposite shell structures of general laminationscontaining piezoelectriclayers. Evaluations of themethod and comparisons with reported results were performed. Numerical results for cylindrical laminated piezoelectric composite panels with continuous piezoceramic actuators and cantilever shells with continuous or discrete piezoelectric actuators and sensors illustrate the advantages of the method and quantify the effects of curvature on the electromechanical response of piezoelectric shells.

25th Anniversary Article: The Evolution of Electronic Skin (E-Skin): A Brief History, Design Considerations, and Recent Progress

Abstract: Human skin is a remarkable organ. It consists of an integrated, stretchable network of sensors that relay information about tactile and thermal stimuli to the brain, allowing us to maneuver within our environment safely and effectively. Interest in large-area networks of electronic devices inspired by human skin is motivated by the promise of creating autonomous intelligent robots and biomimetic prosthetics, among other applications. The development of electronic networks comprised of flexible, stretchable, and robust devices that are compatible with large-area implementation and integrated with multiple functionalities is a testament to the progress in developing an electronic skin (e-skin) akin to human skin. E-skins are already capable of providing augmented performance over their organic counterpart, both in superior spatial resolution and thermal sensitivity. They could be further improved through the incorporation of additional functionalities (e.g., chemical and biological sensing) and desired properties (e.g., biodegradability and self-powering). Continued rapid progress in this area is promising for the development of a fully integrated e-skin in the near future.

Powering MEMS portable devices—a review of non-regenerative and regenerative power supply systems with special emphasis on piezoelectric energy harvesting systems

Abstract: Power consumption is forecast by the International Technology Roadmap of Semiconductors (ITRS) to pose long-term technical challenges for the semiconductor industry. The purpose of this paper is threefold: (1) to provide an overview of strategies for powering MEMS via non-regenerative and regenerative power supplies; (2) to review the fundamentals of piezoelectric energy harvesting, along with recent advancements, and (3) to discuss future trends and applications for piezoelectric energy harvesting technology. The paper concludes with a discussion of research needs that are critical for the enhancement of piezoelectric energy harvesting devices.

Damage detection in composite materials using lamb wave methods

Abstract: Cost-effective and reliable damage detection is critical for the utilization of composite materials. This paper presents part of an experimental and analytical survey of candidate methods for in situ damage detection of composite materials. Experimental results are presented for the application of Lamb wave techniques to quasi-isotropic graphite/epoxy test specimens containing representative damage modes, including delamination, transverse ply cracks and through-holes. Linear wave scans were performed on narrow laminated specimens and sandwich beams with various cores by monitoring the transmitted waves with piezoceramic sensors. Optimal actuator and sensor configurations were devised through experimentation, and various types of driving signal were explored. These experiments provided a procedure capable of easily and accurately determining the time of flight of a Lamb wave pulse between an actuator and sensor. Lamb wave techniques provide more information about damage presence and severity than previously tested methods (frequency response techniques), and provide the possibility of determining damage location due to their local response nature. These methods may prove suitable for structural health monitoring applications since they travel long distances and can be applied with conformable piezoelectric actuators and sensors that require little power.