PSI - Issue 24

Available online at www.sciencedirect.com Structural Int grity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com ScienceDirect

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Procedia Structural Integrity 24 (2019) 267–278

AIAS 2019 International Conference on Stress Analysis Optical Method to measure mesh tensioning Lorenzo Beretta a , Emanuele Marotta a , Pietro Salvini a * a Department of Enterprise Engineering, University of Rome "Tor Vergata", via del Politecnico, 1 00133 - Rome - ITALY AIAS 2019 International Conference on Stress Analysis Optical Method to measure mesh tensioning Lorenzo Beretta a , Emanuele Marotta a , Pietro Salvini a * a Department of Enterprise Engineering, University of Rome "Tor Vergata", via del Politecnico, 1 00133 - Rome - ITALY

Abstract Abstract

© 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the AIAS2019 organizers The present paper presents a method to estimate the tensional status of a knitted mesh. To reach this result, the relationship between the frequencies of vibration, recorded by a high-sampling camera and analysed through image processing, and different tensioning on the mesh itself, has been investigated. After having conducted several tests, all the collected pairs frequency-tensional status have been used to extrapolate an optimal (in a least-squares sense) correlation between frequency of vibration and tension of the mesh. © 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the AIAS2019 organizers The present paper presents a method to estimate the tensional status of a knitted mesh. To reach this result, the relationship between the frequencies of vibration, recorded by a high-sampling camera and analysed through image processing, and different tensioning on the mesh itself, has been investigated. After having conducted several tests, all the collected pairs frequency-tensional status have been used to extrapolate an optimal (in a least-squares sense) correlation between frequency of vibration and tension of the mesh. © 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the AIAS2019 organizers

Keywords: Net Vibrations; Net Stress Measurement; Image Processing Keywords: Net Vibrations; Net Stress Measurement; Image Processing

1. Introduction 1. Introduction

In the last decades, new types of antenna for satellites have been developed. Among them, particular interest is given to AstroMesh® Reflectors, made up of large deployable reflector (LDR), see Fig. 1. They consist in a particular mesh of gold-plated tungsten or molybdenum wires, stretched over a circular low-weight support, and forced so that to approximate a paraboloid shape by two nets, as shown in Fig. 2. What makes the AstroMesh® Reflector so suitable for space missions are their characteristics of extraordinary low weight accompanied by a high stiffness, thermal stability and optimal performance in radio frequency reflectivity, Thomson (2000). The study aims to check the two-dimensional tensioning status acting on the mesh, which must be kept in a defined In the last decades, new types of antenna for satellites have been developed. Among them, particular interest is given to AstroMesh® Reflectors, made up of large deployable reflector (LDR), see Fig. 1. They consist in a particular mesh of gold-plated tungsten or molybdenum wires, stretched over a circular low-weight support, and forced so that to approxi ate a paraboloid shape by two nets, as shown in Fig. 2. What makes the AstroMesh® Reflector so suitable for space missions are their characteristics of extraordinary low weight accompanied by a high stiffness, thermal stability and optimal performance in radio frequency reflectivity, Thomson (2000). The study aims to check the two-dimensional tensioning status acting on the mesh, which must be kept in a defined

* Corresponding author. Tel.: +39.06.7259.7140; fax: +39.06.7259.7145. E-mail address: salvini@uniroma2.it * Corresponding author. Tel.: +39.06.7259.7140; fax: +39.06.7259.7145. E-mail address: salvini@uniroma2.it

2452-3216 © 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the AIAS2019 organizers 2452-3216 © 2019 The Authors. Published by Elsevier B.V. This is an ope access article under t CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the AIAS2019 organizers

2452-3216 © 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the AIAS2019 organizers 10.1016/j.prostr.2020.02.024