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CONTENTS
Volume 3, Number 2, April 2016
 

Abstract
In a whole variety of higher order plate theories existing in the literature no consideration is given to the transverse normal strain / deformation effects on flexural response when these higher order theories are applied to shear flexible composite plates in view of minimizing the number of unknown variables. The objective of this study is to carry out cylindrical bending of simply supported laminated composite and sandwich plates using sinusoidal shear and normal deformation plate theory. The most important feature of the present theory is that it includes the effects of transverse normal strain/deformation. The displacement field of the presented theory is built upon classical plate theory and uses sine and cosine functions in terms of thickness coordinate to include the effects of shear deformation and transverse normal strain. The theory accounts for realistic variation of the transverse shear stress through the thickness and satisfies the shear stress free conditions at the top and bottom surfaces of the plate without using the problem dependent shear correction factor. Governing equations and boundary conditions of the theory are obtained using the principle of minimum potential energy. The accuracy of the proposed theory is examined for several configurations of laminates under various static loadings. Some problems are presented for the first time in this paper which can become the base for future research. For the comparison purpose, the numerical results are also generated by using higher order shear deformation theory of Reddy, first-order shear deformation plate theory of Mindlin and classical plate theory. The numerical results show that the present theory provides displacements and stresses very accurately as compared to those obtained by using other theories.

Key Words
cylindrical bending; shear deformation; normal deformation; laminated plate; sandwich plate; antisymmetric; symmetric; arbitrary laminates

Address
Atteshamuddin S. Sayyad: Department of Civil Engineering, SRES\'s College of Engineering, Savitribai Phule Pune University, Kopargaon-423601, Maharashtra, India
Yuwaraj M. Ghugal: Department of Applied Mechanics, Government Engineering College, Karad-415124, Maharashtra, India

Abstract
Multi-Disciplinary Optimization (MDO) is widely used to handle the advanced design in several engineering applications. Such applications are commonly simulation-based, in order to capture the physics of the phenomena under study. This framework demands fast optimization algorithms as well as trustworthy numerical analyses, and a synergic integration between the two is required to obtain an efficient design process. In order to meet these needs, an adaptive Computational Fluid Dynamics (CFD) solver and a fast optimization algorithm have been developed and combined by the authors. The CFD solver is based on a high-order discontinuous Galerkin discretization while the optimization algorithm is a high-performance version of the Artificial Bee Colony method. In this work, they are used to address a typical aero-mechanical problem encountered in turbomachinery design. Interesting achievements in the considered test case are illustrated, highlighting the potential applicability of the proposed approach to other engineering problems.

Key Words
MDO; swarm intelligence; discontinuous Galerkin; turbomachinery; CFD

Address
Enrico Ampellio: Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino, Italy
Francesco Bertini: GE Avio S.r.l., Rivalta di Torino, Italy
Andrea Ferrero: Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino, Italy
Francesco Larocca: Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino, Italy
Luca Vassio: Department of Electronics and Telecommunications, Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino, Italy

Abstract
The present paper is a review of the main activities carried out within the context of the COMPTINN\" program, a joint research project founded by a FUI program (Fonds Unifiés Interministériels) in which four research teams focused on the thermo-oxidation behaviour of HTS-TACTIX carbon-epoxy composite at \"high\" temperatures (120oC-180oC). The scientific aim of the COMPTINN\" program was to better identify, with a multi-scale approach, the link between the physico-chemical mechanisms involved in thermo-oxidation phenomena, and to provide theoretical and numerical tools for predicting the mechanical behaviour of aged composite materials including damage onset and development.

Key Words
polymer matrix composites; environmental degradation; thermo-oxidation; epoxy resin; micro indentation; delamination

Address
Jacques Cinquin: Airbus Group Innovations, 12 rue Pasteur, 92152 Suresnes, France
Xavier Colin, Bruno Fayolle, Marion Mille, Svetlana Terekhina: Laboratoire PIMM (UMR CNRS 8006), Art et Metiers ParisTech, 151 Boulevard de l\'Hopital, 75013 Paris, France
Laurence Chocinski-Arnault, Marco Gigliotti, Jean-Claude Grandidier,Marie-Christine Lafarie-Frenot, Matteo Minervino: Institut Pprime, CNRS - ENSMA - Universite de Poitiers, UPR 3346, ISAE-ENSMA, 1, avenue Clément Ader, BP 40109, F86961 FUTUROSCOPE CHASSENEUIL Cedex, France
Christophe Cluzel, Federica Daghia, Pierre Ladeveze and Fangzouh Zhang: LMT, ENS Cachan, CNRS, Universite Paris Saclay), 61 avenue du President Wilson, 94235 Cachan Cedex, France

Abstract
The Spacecraft (S/C) numerical sine test-predictions are usually performed through Finite Element Method (FEM) Frequency Response Analysis (FRA), that is the hypothesis of steady-state responses to harmonic excitation to the S/C base is made. In the test practice, the responses are transient and may be significantly different from those predicted through FRA. One of the most significant causes of discrepancy between prediction and test consists in the beating phenomena. After a brief overview of the topic, the typical causes of beating are described in the first part of the paper. Subsequently, focus is made on the sine sweep rate effect, which often leads to have beatings after the resonance of weakly damped modes. In this work, the approach illustrated in the literature for calculating the sine sweep rate effect in the case of Single-Degree-Of-Freedom (SDOF) oscillators is extended to Multi-Degrees-Of-Freedom (MDOF) systems, with the aim of increasing the accuracy of the numerical sine test-predictions. Assumptions and limitations of the proposed methodology are detailed along the paper. Several assessments with test results are discussed and commented.

Key Words
sine sweep rate effect; sine test-predictions; beating phenomena; sine testing; FRA

Address
Pietro Nali: Thales Alenia Space Italy, Strada antica di Collegno, 253 - 10146, Turin, Italy
Alain Bettacchioli: Thales Alenia Space France, 5 Allée des Gabians - 06150 Cannes, France

Abstract
The present study aims to investigate the shimmy stability behavior of a single wheeled nose landing gear system. The system is supposed to be equipped with an electromechanical actuator capable to control the shimmy vibrations. A Proportional-Integrative-Derivative (PID) controller, tuned by using the Particle Swarm Optimization (PSO) procedure, is here proposed to actively damp the shimmy vibration. Time-history results for some test cases are reported and commented. Stochastic analysis is last presented to assess the robustness of the control system.

Key Words
nose landing gear; shimmy vibration; active control

Address
Andrea Alaimo: Universita di Enna \"Kore\", Cittadella Universitaria 94100, Enna, Italy
Alberto Milazzo: Universita di Palermo, Viale delle Scienze Ed. 8, 90128 Palermo, Italy
Calogero Orlando: Universita di Enna \"Kore\", Cittadella Universitaria 94100, Enna, Italy

Abstract
Euclid is an astronomy and astrophysics space mission of the European Space Agency. The mission aims to understand why the expansion of the Universe is accelerating and what is the nature of the source responsible for this acceleration which physicists refer to as dark energy. This paper provides both an overview of the spacecraft mechanical architecture and a synthesis of the process applied to establish adequate mechanical loads for design and testing. Basic methodologies and procedures, logics and criteria which have been used with the target to meet a compliant, \"optimised\" design are illustrated. The strategy implemented to limit the risk for overdesign and over-testing without jeopardizing the design margins is also addressed.

Key Words
design loads; loads analysis; structural dynamics; Euclid spacecraft

Address
Adriano Calvi: European Space Agency, Keplerlaan 1, PO Box 299, 2200 AG Noordwijk, The Netherlands
Patrizia Bastia: Thales Alenia Space Italy, Strada Antica di Collegno 253, 10143 Torino, Italy


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