Georgios Eleftherios Stavroulakis

Georgios Eleftherios Stavroulakis
Technical University of Crete | TUC · School of Production Engineering and Management

Professor Dr.Eng., habil., Prof. h.c.

About

442
Publications
74,700
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
3,760
Citations
Introduction
Georgios E. Stavroulakis currently works at the School of Production Engineering and Management, Technical University of Crete. Georgios does research in Materials Science and Mechanics, Optimal Design as well as Dynamics, Vibration and Control. Their current projects are 'Fuzzy and Neuro-fuzzy control of Structures.', 'Neural networks in mechanics' and 'Auxetic Materials and Structures, Dynamic Vibration Damping, Additive Manufacturing and Topology Optimization',
Additional affiliations
September 2005 - present
Technical University of Crete
Position
  • Professor (Full)
Description
  • www.comeco.tuc.gr
January 2001 - August 2005
University of Ioannina
Position
  • Professor (Associate)
January 1996 - December 2000
Technische Universität Braunschweig
Position
  • Professor (Assistant)
Education
September 1998 - June 2020
November 1985 - June 1991
Aristotle University of Thessaloniki
Field of study
  • Civil Engineering, Mechanics
September 1979 - November 1985
Aristotle University of Thessaloniki
Field of study
  • Civil Engineering

Publications

Publications (442)
Article
Full-text available
Certain frequency ranges where waves do not propagate, and thus, vibrations are suppressed, are called band gaps. In the present paper, the appearance and the behavior of such areas are investigated on star-shaped auxetic microstructures, which are equipped with shunted piezoelectric elements. The optimal position of the piezoelectric patches is fo...
Article
Full-text available
Sheet metal forming is one of the most important manufacturing processes applied in many industrial sectors, with the most prevalent being the automotive and aerospace industries. The main purpose of that operation is to produce a desired formed shape blank, without any material failures, which should lie well within the acceptable tolerance limits...
Article
Full-text available
A band gap region, or simply a band gap, is a range of frequencies where vibrations of certain frequency ranges are isolated. In the present paper, such ranges are sought through the study of different cases for the shape of the unit cells of a lattice, i.e., of an assembly of classical structural elements, such as beams and plates. A lattice with...
Article
Full-text available
An omnidirectional source is required in many acoustic measurements. Commonly a dodecahedron speaker is used but due to various factors (e.g., high cost, transportation difficulties) other acoustic sources are sometimes preferred. In this review, fifteen acoustic source alternatives to a dodecahedron speaker are presented while emphasis is placed o...
Article
In this article an overall procedure is proposed, for the numerical investigation of the structural response of ancient monuments made of megalithic stones. The procedure is implemented on the middle temple of the Mnajdra Megalithic structure, listed as UNESCO World Heritage and regarded as one of the oldest structures from early civilization datin...
Article
Full-text available
Additive Manufacturing (AM) is a well-known and rapidly advancing method, especially in the manufacturing of high-strength and lightweight microstructures. Utilizing AM, it is possible to fabricate any structure as complicated as it is. For an efficient and cost-effective printing, a critical parameter is the infill, which can be characterized from...
Data
The provided Python code solves the example given in our publication https://www.researchgate.net/publication/361148205_A_Gentle_Introduction_to_Physics-Informed_Neural_Networks_with_Applications_in_Static_Rod_and_Beam_Problems which in turn is based on the diploma thesis of the first author (in Greek) https://dias.library.tuc.gr/view/90771
Book
Full-text available
Satisfactory acoustics is crucial for the ability of spaces, such as auditoriums and lecture rooms, to perform their primary function. The acoustics of dwellings and offices greatly affects our life quality, since we are all consciously or subconsciously aware of the sounds to which we are subjected to daily. Architectural acoustics, which encompass...
Article
Full-text available
A modern approach to solving mathematical models involving differential equations, the so-called Physics-Informed Neural Network (PINN), is based on the techniques which include the use of artificial neural networks and the method of fitting the governing differential equations at collocation points. In this paper, training of the PINN with an appl...
Conference Paper
Full-text available
Usage of artificial intelligence methods and especially feedforward artificial neural networks which can be trained by the backpropagation method has a long history in mechanics. By using input-output examples experimentally generated or numerically calculated, direct and inverse problems in mechanics can be studied [1-4]. Complicated metamodels ca...
Article
This article presents an investigation of the structural behavior of a masonry arch bridge in Turkey. An analytical study has been conducted to provide the geometry of the structure, using laser scanning. A point cloud describing the geometry was obtained and properly transformed into a format that is appropriate for structural analysis software (C...
Book
Nonlinear Mechanics for Composite Heterogeneous Structures applies both classical and multi-scale finite element analysis to the non-linear, failure response of composite structures. These traditional and modern computational approaches are holistically presented, providing insight into a range of non-linear structural analysis problems. The classi...
Article
Full-text available
Satisfactory acoustics is crucial for the ability of spaces such as auditoriums and lecture rooms to perform their primary function. The acoustics of dwellings and offices greatly affects the quality of our life since we are all consciously or subconsciously aware of the sounds to which we are daily subjected. The aim of this special issue was to g...
Article
Full-text available
The structural behavior of Neoria masonry monument is studied here. The determination of structural and material properties of a partially collapsed monument and the evaluation of existing damages and their importance for further restoration studies are not trivial tasks. The investigation has been based on detailed geometric data, collected from s...
Chapter
Over the last years, the significant progress of the Additive Manufacturing techniques gave rise to a great evolution in the designing method of mechanical components. This paper studies the utilization of the generative design in the redesigning of a Φ32 mm pneumatic cylinder mounting. The following mountings are considered: the Pivot bracket with...
Article
Materials with negative Poisson?s ratio are called auxetics and they present enhanced properties (e.g. damping, indentation resistance, fracture toughness and impact resistance) under external loadings. The auxetic properties are derived from peculiar-shaped microstructures, such as starshaped frames. In the present investigation, several applicati...
Article
Full-text available
Kirchhoff plate bending and Winkler-type contact problems with different boundary conditions are solved with the use of physics-informed neural networks (PINN). The PINN is built on the base of mechanics laws and deep learning. The idea of the technique includes fitting the governing partial differential equations at collocation points and then tra...
Article
Vibration suppression has been thoroughly studied in the last few years. A number of methods has been proposed for this purpose. An evolving method lies in the search of band gap regions, that is, certain frequency ranges where vibrations are isolated. In the present investigation, a periodic unit cell of a chiral metamaterial has been created in o...
Chapter
Credit insurance is of vital importance for the trade sector and almost every related business. Moreover, every policy in credit insurance is tailor-made in order to suit in the best available way the unique needs and demands of the insured business. Thus, pricing of such service can be tricky for an insurance company. In the present chapter, this...
Article
Full-text available
Fusion of data mining and computational mechanics is a modern approach for the exploitation of available data within rigorous modelling. First steps in this direction have been focused on the usage of neural networks and other soft computing tools as metamodeling tools. This framework seems suitable for numerical homogenization techniques realized...
Article
Full-text available
Noise barriers are a critical part of noise mitigation in urban and rural areas. In this study, a comparison of the insertion loss calculations of noise barriers via the Finite Element Method (FEM) and various formulae (Kurze–Anderson, ISO 9613-2/Tatge, Menounou) is presented in the case of two-dimensional acoustic radiation problems. Some of the c...
Article
Full-text available
The designing process of a new product includes various stages, one of which is the evaluation of an idea thought prototype manufacturing. The use of additive manufacturing consists the most efficient and effective way for prototype manufacturing. In order to maximize the benefits from the use of additive manufacturing, we should choose the suitabl...
Article
Full-text available
A handclap is a convenient and easily available source for room acoustic measurements. If used correctly (e.g., application of optimal hand configuration) it can provide usable results for the measurement of acoustic parameters, within an expected deviation. Its biggest drawbacks are the low sound pressure level (especially in the low frequency ran...
Preprint
Vibration suppression in a field of frequencies and the creation of band gaps which do not allow the propagation of the waves is studied in this paper by means of microstructures designed through topology optimization. Topology optimization is formulated in frequency domain. Band gap design is based on Floquet-Bloch theory and genetic optimization....
Article
Optimal design and analysis of three-phase graphene/fibre reinforced laminated nanocomposite plates with respect to maximizing the fundamental frequency is the subject of the present study. Optimal design solutions are given for four different sets of design parameters. First design problem determines the optimal graphene contents of individual lay...
Article
By defining the limits and the design specification, that an underwater robotic vehicle should fulfill in order to be characterized as biomimetic, a shell structure with a modular locomotion mechanism is proposed, using THUNDER piezoelectric, for a novel biomimetic underwater robot. Smart materials and especially piezoelectric actuators are an exce...
Article
Full-text available
A review of mathematical models for elastic plates with buckling and contact phenomena is provided. The state of the art in this domain is presented. Buckling effects are discussed on an example of a system of nonlinear partial differential equations, describing large deflections of the plate. Unilateral contact problems with buckling, including mo...
Article
Full-text available
Handclap is a convenient and useful acoustic source. This study sets to explore its optimal application and limitations for acoustic measurements as well for other possible utilizations. For this purpose the following steps were performed: investigation of the optimal hand configuration for acoustic measurements, measurements at different microphon...
Chapter
Masonry structures without mortar or with mortar of low quality are used in several infrastructures, like bridges and retaining walls Unilateral contact plays a crucial role in their stability. Limit analysis and nonexistence of solution are related to the creation of collapse mechanisms. Open source and freely available software can be used for th...
Chapter
During the last decades, floods are getting more and more dangerous and they cause a lot of destruction either for human lives and/or for people’s properties. Due to different climate conditions, some parts of the world present increased levels of danger from floods. For this reason, the development of a robust tool for the prediction of floods is...
Book
This book summarizes the research being pursued as part of the Erasmus+ CBHE KA2 project entitled "Development of master curricula for natural disasters risk management in Western Balkan countries” (NatRisk), which aims to educate experts on the prevention and management of natural disasters in the Western Balkan region in line with national and EU...
Article
Full-text available
Due to recent developments in the field of additive manufacturing enormous advantages have become in product design and manufacturing process. Before the appearance of additive manufacturing, developing very complex or light weight structures was difficult to manufacture. The development of artificial intelligent technology helps to develop new col...
Article
In light of past research in this field, this paper intends to discuss some innovative approaches in vibration control of smart structures, particularly in the case of structures with embedded piezoelectric materials. In this work, we review the principal problems in mechanical engineering that the structural control engineer has to address when de...
Chapter
Full-text available
In this work, shape control of flexible structures using enforced deformations as control actions and nature-inspired, gradient-free, global optimization techniques is considered. The proposed scheme can be applied for morphing of truss structures, such as a radio-telescope bases, aircraft smart wings, spray booms etc. A static problem for differen...
Chapter
Classical control tools often encounter a number of limitations on the investigation of smart composite structures due to nonlinearities and/or other uncertainties. Especially in smart structures, which is the case here, a significant degree of uncertainty is involved due to several imperfections and/or errors of both the controller and the structu...
Conference Paper
Full-text available
A new design starts from an idea and become a final product, during design process the evaluation stage it's a necessity, the most useful evaluation tool is prototyping. Conceptual models are very important in product design. Improving product quality is always an important issue of manufacturing, even if a design study is well organized it is poss...
Conference Paper
The suppression of the oscillations of structures is a significant field of study for the mechanical and structural engineers and designers. During the past years, several techniques of design and control have been developed in order to achieve this goal. One of these techniques consists of the combination of the analysis of a periodic representati...
Chapter
In the present chapter, optimal design problems related to smart composites are investigated. First, the mechanical properties of a smart composite can be tailored to meet required specifications. Beyond classical shape and layout optimization related to the layers of a composite, pointwise optimization leading to functionally graded composites or...
Article
Full-text available
In this paper, the current state of the art on shunt piezoelectric systems for noise and vibration control is reviewed. The core idea behind the operation of electronic shunt piezoelectric circuits is based on their capability of transforming the dynamic strain energy of the host structure, i.e., a smart beam or plate, into electric energy, using t...
Article
This paper deals with the advantages of robust control in smart structures. First we present the implementations of H infinity control in the frequency domain. A dynamic model for smart structure under wind excitations is considered. Then robust control theory is used a model to synthesize controllers achieving stabilization with guaranteed perform...
Article
This paper deals with the advantages of robust control in smart structures. First we present the implementations of H infinity control in the frequency domain. A dynamic model for smart structure under wind excitations is considered. Then robust control theory is used a model to synthesize controllers achieving stabilization with guaranteed perform...
Article
Full-text available
A breakthrough in the process method has been developed by combined considerations in the demands of "Shell Eco Marathon" using finite element modelling (FEM). Ultrafast calculations have revealed novel chassis development. The most critical factors in designing the new chassis are the reduction of the weight, the improvement of strength and stiffn...
Article
Full-text available
In the present investigation, the principles of dynamic morphing of smart truss structures and mechanisms are discussed. A possible way in order to find the optimal geometry of the structure for the enhancement of structural performance in terms of vibration control is sought. The vibrations of the host dynamic structures are monitored by controlle...
Conference Paper
Classical linear-quadratic-regulators (LQR) provide the basis of well-known active optimal problems in mechanical engineering. They concern control of linear dynamical systems with a quadratic cost function. Their effi-ciency deteriorates as the uncertaincy of the loading and/or of the structural system becomes higher. Robust control theories (e.g....
Conference Paper
In this paper, a sampled-data state feedback H-control technique is proposed, in order to attenuate nozzle disturbances of flexible crop sprayers. The design objective here, is to reduce the effect of the disturbances on the outputs of the sprayer, to an acceptable level, by minimizing the maximum vertical displacements of the tips of the spray bo...
Conference Paper
The purpose of this paper is a preliminary study of optimal control problems for nonlinear structures and especially for structures with nonsinooth nonlinearities.Unilateral contact effects and friction are the most common effects in this class of problems. A review of recent applications in engineering is included. Simple academic examples solved...
Conference Paper
Classical linear-quadratic-regulators (LQR), provide the basis of well-known active optimal problems in mechanical engineering. They concern control of linear dynamical systems with a quadratic cost function. Their efficiency deteriorates as the uncertaincy of the loading and/or of the structural system becomes higher. Robust control theories (e.g....
Conference Paper
A comparison between classical linear quadratic optimal control and robust H¥ control is done in this paper. The advantages of modern control concepts and their many possibilities for innovative active seismic design are shown with the help. of numerical computations of a shear type frame structure, a widely accepted structural model for ordinary b...
Article
Full-text available
The increasing demand for energy efficient electric cars, in the automotive sector, entails the need for improvement of their structures, especially the chassis, because of its multifaceted role on the vehicle dynamic behaviour. The major criteria for the development of electric car chassis are the stiffness and strength enhancement subject to mass...
Chapter
Centre-pivot irrigation systems, also known as flexible sprayer booms, are efficiently used in the watering process and irrigation applications. During the use of such systems, various problems can occur, due to vibrations caused either by the wind excitation or other, mainly steep, external loadings, which in turn can be caused by the uneven surfa...
Chapter
Methods used for the structural evaluation of masonry structures and monuments are presented in this article. Limit analysis is initially presented as a tool for the study of the collapse mechanism and limit load of masonry structures. Unilateral contact-friction laws are introduced between the stones, to describe damage due to opening-sliding. Rel...
Article
Full-text available
A computational homogenization method is presented in this article, for the investigation of localization phenomena arising in periodic masonry structures. The damage of the macroscopic, structural scale is represented by cohesive cracks, simulated by the extended finite element method. The cohesive traction–separation law along these cracks is bui...
Article
In this work, an inverse analysis procedure adopting a Bayesian approach is proposed as a numerical tool to investigate the causes that have led a masonry arch bridge to be in a certain pathological condition. Within this framework, the damaged condition investigation is formulated as a parameter estimation problem. A nonlinear finite element model...
Article
Full-text available
Alternative low-cost sources (e.g., balloons, gun fires) are used for impulse response measurements when a dodecahedron speaker is not available. This study sets to explore the applicability of a method utilizing a common directional loudspeaker as a sound source. For this purpose measurements were performed in three spaces with three different com...
Conference Paper
In the present investigation, a band-gap region, i.e. the isolation of certain frequencies, through the optimization of the shape of the unit cells of a lattice is considered. In general, a lattice is considered as an assembly of classical structural elements, such as beams, plates, etc. Each cell of the lattice is discretized using the finite elem...
Article
Full-text available
In this article a numerical approach is proposed for the investigation of composite materials, like masonry. A number of simulations of a nonlinear, heterogeneous microstructure with gradually increasing loading, are considered. Average stress and stiffness are also derived. Then, this information is incorporated in databases, and a metamodel is cr...