IMPACT ACOUSTIC ISOLATION OF ETHYLENE VINYL ACETATE PANELS

[EN] Ethylene Vinyl Acetate (EVA) foam is used in fitness facilities floors because of its shock absorption and isolation properties. Varying some material properties such as density and thickness, a range of these materials have been studied in order to evaluate their dynamic and acoustic behaviour. Two material properties (dynamic stiffness, and sound absorption coefficient) have been characterized according to the corresponding standards: ISO 9052 and ISO 10534-2. The results provide useful information to evaluate the influence of the density and thickness in the dynamic and acoustic behaviour of these materials.Segura Alcaraz, JG.; Juliá Sanchis, E.; Gadea Borrell, JM. (2015). IMPACT ACOUSTIC ISOLATION OF ETHYLENE VINYL ACETATE PANELS. ANNALS of the UNIVERSITY of ORADEA. Fascicle of Management and Technological Engineering. XIV:245-248. http://hdl.handle.net/10251/99708S245248XI

Experimental and Numerical Acoustic Characterization of Laminated Floors

[EN] This work has focused on characterizing laminated floors from the sound perception perspective. There are two main aspects in this work. The first is an alternative proposed for experimental characterization, which consists in recording the sound generated by the impact of a steel ball when it falls on a laminated floor from a known height. The second is a numerical hybrid FEM-FDTD model. The numerical model uses FEM to simulate the mechanical part of the experiment when the ball impacts the floor. The results are implemented into a FDTD algorithm to take into account the acoustic part of the problem and to obtain the sound pressure level of the microphone. This numerical model is useful for identifying laminated floors if the mechanical properties of the material are known, and to characterize them from the sound perception perspective.Gadea Borrell, JM.; Segura Alcaraz, JG.; Juliá Sanchis, E. (2015). Experimental and Numerical Acoustic Characterization of Laminated Floors. Experimental Techniques. 40(2):857-863. doi:10.1111/ext.12132S85786340

Teaching based on challenges for the subject steel structures

[EN] The evolution of information and communication technologies has changed the way in which agents involved in teaching have access to information. The classic concept of transmission of knowledge, valid 30 years ago, of a lecture (message) in a physical classroom (space) at a certain time (time) has now become obsolete. There are many disciplines taught in universities that can adapt their teaching model to hybrid face-to-face and online systems, where class time is used in the application and discovery of knowledge by the student. In this paper, a learning methodology based on challenges is proposed for the subject of Steel Structures of the Degree in Mechanical Engineering of the Universitat Politècnica de València. The organization of the contents and didactic tools used: tele-training platforms, flipped teaching, commercial software for steel structures ..., allows the teaching of the subject to be carried out face-to-face or online without changes and brings the student closer to the professional reality of steel structures. The results obtained during the last 5 years show a high percentage of passes and a high degree of student satisfaction based on surveys.Segura Alcaraz, JG.; Juliá Sanchis, E.; Montava-Belda, I.; Gadea Borrell, JM. (2021). Teaching based on challenges for the subject steel structures. EDULEARN Proceedings (Internet). 812-815. https://doi.org/10.21125/edulearn.2021.0219S81281

Learning mechanics of materials by doing models

[EN] Mechanics of Materials is a discipline taught to the second-year students in the Bachelor Degree of Mechanical Engineering at Universitat Politècnica de València, Alcoi Campus. The teaching-learning process is focused on three main aspects: theory, practice, and numerical simulations. There are several experiments designed to better understand the mechanical behaviour of the materials that are present in buildings and machines. This paper explains the application of another hands-on methodology that has been included in the course. It consists of completing the process by constructing or prototyping scale models which help the students to understand how the structures work in real life. The results of the experience allow us to consider that learning by doing has supposed a significant step in the comprehension of the Mechanics of Materials and the students have showed a positive attitude towards this activity. Not only by constructing models, but the fact that their construction is blended with other active methodologies, contribute to enhance the motivation in learning the subject.Montava-Belda, I.; Juliá Sanchis, E.; Gadea Borrell, JM.; Segura Alcaraz, JG. (2021). Learning mechanics of materials by doing models. EDULEARN Proceedings (Internet). 806-811. https://doi.org/10.21125/edulearn.2021.0218S80681

Spreadsheet solution of basic axial force problems of strength of materials

In this work, we present a spreadsheet developed for some particular problems of Strength of Materials. This paper is focused on the study of axial force systems, some statically determinate, such as trusses, and some statically indeterminate, such as a load-carrying rigid member supported by a pinned connection and by two axial bars. Starting with simple calculations for a particular problem, students develop the spreadsheet with more advanced calculations. The examples have been modelled on Microsoft Excel software. The aim is that, at the end of the course, students have developed a collection of such spreadsheets. This methodology contributes to enhancing the motivation in the study of the subject, which is the main learning objective.Juliá Sanchis, E.; Segura Alcaraz, JG.; Gadea Borrell, JM. (2010). Spreadsheet solution of basic axial force problems of strength of materials. Spreadsheets in Education. 4(1):1-11. http://hdl.handle.net/10251/62606S1114

Panels of eco-friendly materials for architectural acoustics

[EN] The objective of this work is to study the acoustic and mechanical properties of environmentally friendly materials manufactured through the process of resin infusion made from different types of fibres: some are biodegradable obtained from renewable resources and others from recycled textile waste. The materials studied are composed of fibres of jute, hemp, coconut, biaxial linen and textile waste. The modulus of elasticity and the airborne sound insulation are determined through dynamic and acoustic tests, respectively. The behaviour of these innovative materials is compared to some traditional materials commonly used in architectural acoustics. The acoustic study of these environmentally friendly materials is carried out considering them as light elements of a single layer for their application to insulation of walls. The results are compared to plasterboards, considered as the most commonly used light material in buildings for airborne sound insulation. In conclusion, these materials are a real and effective alternative to the traditional composites of synthetic matrices and reinforcements of glass fibres and there is a reduction in the production cost compared to the usual porous synthetic media that have expensive production processes.Fontoba-Ferrándiz, J.; Juliá Sanchis, E.; Crespo, J.; Segura Alcaraz, JG.; Gadea Borrell, JM.; Parres, F. (2020). Panels of eco-friendly materials for architectural acoustics. Journal of Composite Materials. 54(25):3743-3753. https://doi.org/10.1177/0021998320918914S374337535425Yahya, M. N., Sambu, M., Latif, H. A., & Junaid, T. M. (2017). A study of Acoustics Performance on Natural Fibre Composite. IOP Conference Series: Materials Science and Engineering, 226, 012013. doi:10.1088/1757-899x/226/1/012013Putra, A., Or, K. H., Selamat, M. Z., Nor, M. J. M., Hassan, M. H., & Prasetiyo, I. (2018). Sound absorption of extracted pineapple-leaf fibres. Applied Acoustics, 136, 9-15. doi:10.1016/j.apacoust.2018.01.029Dunne, R., Desai, D., & Sadiku, R. (2017). Material characterization of blended sisal-kenaf composites with an ABS matrix. Applied Acoustics, 125, 184-193. doi:10.1016/j.apacoust.2017.03.022Mohanty, A. K., Misra, M., & Hinrichsen, G. (2000). Biofibres, biodegradable polymers and biocomposites: An overview. Macromolecular Materials and Engineering, 276-277(1), 1-24. doi:10.1002/(sici)1439-2054(20000301)276:13.0.co;2-wLuckachan, G. E., & Pillai, C. K. S. (2011). Biodegradable Polymers- A Review on Recent Trends and Emerging Perspectives. Journal of Polymers and the Environment, 19(3), 637-676. doi:10.1007/s10924-011-0317-1Belakroum, R., Gherfi, A., Kadja, M., Maalouf, C., Lachi, M., El Wakil, N., & Mai, T. H. (2018). Design and properties of a new sustainable construction material based on date palm fibers and lime. Construction and Building Materials, 184, 330-343. doi:10.1016/j.conbuildmat.2018.06.196Sèbe, G. (2000). Applied Composite Materials, 7(5/6), 341-349. doi:10.1023/a:1026538107200Yates, M. R., & Barlow, C. Y. (2013). Life cycle assessments of biodegradable, commercial biopolymers—A critical review. Resources, Conservation and Recycling, 78, 54-66. doi:10.1016/j.resconrec.2013.06.010Rouison, D., Sain, M., & Couturier, M. (2006). Resin transfer molding of hemp fiber composites: optimization of the process and mechanical properties of the materials. Composites Science and Technology, 66(7-8), 895-906. doi:10.1016/j.compscitech.2005.07.040Sreekumar, P. A., Joseph, K., Unnikrishnan, G., & Thomas, S. (2007). A comparative study on mechanical properties of sisal-leaf fibre-reinforced polyester composites prepared by resin transfer and compression moulding techniques. Composites Science and Technology, 67(3-4), 453-461. doi:10.1016/j.compscitech.2006.08.025Rassmann, S., Reid, R. G., & Paskaramoorthy, R. (2010). Effects of processing conditions on the mechanical and water absorption properties of resin transfer moulded kenaf fibre reinforced polyester composite laminates. Composites Part A: Applied Science and Manufacturing, 41(11), 1612-1619. doi:10.1016/j.compositesa.2010.07.009Vijay, R., & Singaravelu, D. L. (2016). Experimental investigation on the mechanical properties ofCyperus pangoreifibers and jute fiber-based natural fiber composites. International Journal of Polymer Analysis and Characterization, 21(7), 617-627. doi:10.1080/1023666x.2016.1192354Williams, G. I. (2000). Applied Composite Materials, 7(5/6), 421-432. doi:10.1023/a:1026583404899O’Donnell, A., Dweib, M. ., & Wool, R. . (2004). Natural fiber composites with plant oil-based resin. Composites Science and Technology, 64(9), 1135-1145. doi:10.1016/j.compscitech.2003.09.024Tran, P., Graiver, D., & Narayan, R. (2006). Biocomposites synthesized from chemically modified soy oil and biofibers. Journal of Applied Polymer Science, 102(1), 69-75. doi:10.1002/app.22265Liu, Q., & Hughes, M. (2008). The fracture behaviour and toughness of woven flax fibre reinforced epoxy composites. Composites Part A: Applied Science and Manufacturing, 39(10), 1644-1652. doi:10.1016/j.compositesa.2008.07.008Scarponi, C., Pizzinelli, C. S., Sánchez-Sáez, S., & Barbero, E. (2009). Impact Load Behaviour of Resin Transfer Moulding (RTM) Hemp Fibre Composite Laminates. Journal of Biobased Materials and Bioenergy, 3(3), 298-310. doi:10.1166/jbmb.2009.1040Dahy, H. (2017). Biocomposite materials based on annual natural fibres and biopolymers – Design, fabrication and customized applications in architecture. Construction and Building Materials, 147, 212-220. doi:10.1016/j.conbuildmat.2017.04.079Saba, N., Paridah, M. T., & Jawaid, M. (2015). Mechanical properties of kenaf fibre reinforced polymer composite: A review. Construction and Building Materials, 76, 87-96. doi:10.1016/j.conbuildmat.2014.11.043Senthilkumar, K., Saba, N., Rajini, N., Chandrasekar, M., Jawaid, M., Siengchin, S., & Alotman, O. Y. (2018). Mechanical properties evaluation of sisal fibre reinforced polymer composites: A review. Construction and Building Materials, 174, 713-729. doi:10.1016/j.conbuildmat.2018.04.143Alves, C., Ferrão, P. M. C., Silva, A. J., Reis, L. G., Freitas, M., Rodrigues, L. B., & Alves, D. E. (2010). Ecodesign of automotive components making use of natural jute fiber composites. Journal of Cleaner Production, 18(4), 313-327. doi:10.1016/j.jclepro.2009.10.022Van Vuure, A. W., Baets, J., Wouters, K., & Hendrickx, K. (2015). Compressive properties of natural fibre composites. Materials Letters, 149, 138-140. doi:10.1016/j.matlet.2015.01.158Galan-Marin, C., Rivera-Gomez, C., & Garcia-Martinez, A. (2016). Use of Natural-Fiber Bio-Composites in Construction versus Traditional Solutions: Operational and Embodied Energy Assessment. Materials, 9(6), 465. doi:10.3390/ma9060465Bogoeva-Gaceva, G., Avella, M., Malinconico, M., Buzarovska, A., Grozdanov, A., Gentile, G., & Errico, M. E. (2007). Natural fiber eco-composites. Polymer Composites, 28(1), 98-107. doi:10.1002/pc.20270Peng, L., Song, B., Wang, J., & Wang, D. (2015). Mechanic and Acoustic Properties of the Sound-Absorbing Material Made from Natural Fiber and Polyester. Advances in Materials Science and Engineering, 2015, 1-5. doi:10.1155/2015/274913Benfratello, S., Capitano, C., Peri, G., Rizzo, G., Scaccianoce, G., & Sorrentino, G. (2013). Thermal and structural properties of a hemp–lime biocomposite. Construction and Building Materials, 48, 745-754. doi:10.1016/j.conbuildmat.2013.07.096Adekomaya, O., Jamiru, T., Sadiku, R., & Huan, Z. (2015). A review on the sustainability of natural fiber in matrix reinforcement – A practical perspective. Journal of Reinforced Plastics and Composites, 35(1), 3-7. doi:10.1177/0731684415611974Kadam, A., Pawar, M., Yemul, O., Thamke, V., & Kodam, K. (2015). Biodegradable biobased epoxy resin from karanja oil. Polymer, 72, 82-92. doi:10.1016/j.polymer.2015.07.002Yan, L., Chouw, N., & Jayaraman, K. (2014). Flax fibre and its composites – A review. Composites Part B: Engineering, 56, 296-317. doi:10.1016/j.compositesb.2013.08.014Wambua, P., Ivens, J., & Verpoest, I. (2003). Natural fibres: can they replace glass in fibre reinforced plastics? Composites Science and Technology, 63(9), 1259-1264. doi:10.1016/s0266-3538(03)00096-4Williams, C., Summerscales, J., & Grove, S. (1996). Resin Infusion under Flexible Tooling (RIFT): a review. Composites Part A: Applied Science and Manufacturing, 27(7), 517-524. doi:10.1016/1359-835x(96)00008-5Modi, D., Correia, N., Johnson, M., Long, A., Rudd, C., & Robitaille, F. (2007). Active control of the vacuum infusion process. Composites Part A: Applied Science and Manufacturing, 38(5), 1271-1287. doi:10.1016/j.compositesa.2006.11.012Corbière-Nicollier, T., Gfeller Laban, B., Lundquist, L., Leterrier, Y., Månson, J.-A. ., & Jolliet, O. (2001). Life cycle assessment of biofibres replacing glass fibres as reinforcement in plastics. Resources, Conservation and Recycling, 33(4), 267-287. doi:10.1016/s0921-3449(01)00089-1Del Rey, R., Alba, J., Bertó, L., & Gregori, A. (2017). Small-sized reverberation chamber for the measurement of sound absorption. Materiales de Construcción, 67(328), 139. doi:10.3989/mc.2017.0731

Correlations between acoustic and electrochemical measurements for metallic corrosion on steel strings used in guitars

The corrosion state of steel guitar strings and their morphology were evaluated according to exposure time to artificial human sweat solution. The instantaneous corrosion rate was evaluated using polarization resistance. Electrochemical impedance spectroscopy was used to measure the strings' state due to corrosion in artificial human sweat solution. Modification of vibroacoustic parameters was analyzed: changes in harmonic content of sound were studied by means of the Fast Fourier Transform and spectrograms. The correlation between corrosion and acoustic measurements was established in the successive stages of corrosion. Thus, the strings' acoustic properties could be modified by means of controlled corrosion processes. (C) 2015 Elsevier Ltd. All rights reserved.The authors wish to thank to the Spanish Ministerio de Ciencia e Innovacion (contract CTM2011-23583) for the financial support.López Muelas, JL.; Bonastre Cano, JA.; Segura Alcaraz, JG.; Gadea Borrell, JM.; Juliá Sanchis, E.; Cases Iborra, FJ. (2015). Correlations between acoustic and electrochemical measurements for metallic corrosion on steel strings used in guitars. Engineering Failure Analysis. 57:270-281. https://doi.org/10.1016/j.engfailanal.2015.07.014S2702815

An application of an optimization tool to solve problems of mechanics of materials

This paper presents a study about using computational tools applied to a particular problem of Mechanics of Materials. Our purpose is, on one hand, to solve a structural problem in order to teach the application of an optimization tool, such as Excel Solver, by means of the calculation of the minimum weight in a shaft. On the other hand, we present an active learning methodology based on the creation of spreadsheets that contributes to enhancing the motivation of students. Since the evaluation of the subject takes into account the activity of creating the spreadsheets, the academic results have improved considerably.Juliá Sanchis, E.; Segura Alcaraz, JG.; Gadea Borrell, JM.; Masiá Vañó, J. (2011). An application of an optimization tool to solve problems of mechanics of materials. Spreadsheets in Education. 5(1):1-10. http://hdl.handle.net/10251/57511S1105

Study of the acoustic absorption properties of panels made from ground tire rubbers

[EN] The present study is conducted to characterize multilayer acoustic panels made from recycled tire rubbers (GTR’s) in order to determine the sound absorption characteristics of these new materials for different applications, trying to give an answer to the environmental problem generated by this waste. This waste is currently used as modifier of asphalt, sport surfaces, molded and calendered products. The article is a first step to evaluate the sound absorption of these new multilayer panels for application in fields such as noise barriers, noise of machinery and equipment, conditioning acoustic enclosures, etc. Basically two types of products can be obtained from the waste of the tyres: fibers and rubbers. Two types of multilayer panels of thickness 10 mm and 20 mm have been made for a three layer disposition: rubber-fibre-rubber. Then, the standing wave tube method has been used to determine the sound absorption in these materials. For rubber there are 0,7 mm and 2,2-4 mm granulometry. The results show that multilayer panels made of 2,2-4 granulometry present a higher acoustic absorption in the studied frequency range (400-3500 Hz). By increasing the thickness of the panel, the sound absorption coefficient is higher and the multilayer panel increases its sound absorption by adding more percentage of rubber.[ES] En este trabajo se realiza un estudio de la absorción acústica de paneles multicapa conformados por materiales provenientes de neumáticos reciclados (GTR's), tratando de dar una repuesta al problema medioambiental generado por estos residuos. Estos materiales encuentran aplicación en aditivos para asfaltos, superficies deportivas o de parques infantiles, productos moldeados y calandrados. Del residuo de neumático se obtienen básicamente dos tipos de producto: fibras y caucho. El artículo se enmarca como un primer paso para la evaluación de la absorción acústica de estos nuevos paneles multicapa para su aplicación en ámbitos como barreras acústicas, insonorización de maquinaria y equipos industriales, acondicionamiento acústico de recintos, etc. Se han preparado dos tipos básicos de paneles multicapa con 10 y 20 mm de espesor. Cada panel multicapa está constituido por tres capas de diferentes espesores siempre con la disposición caucho-fibra-caucho. Para determinar el coeficiente de absorción se ha utilizado el método del tubo de impedancia acústica. Para el caucho se ha trabajado con granulometrías de entre 0,7 y 2,2-4 mm. Los resultados demuestran que los paneles multicapa con caucho de granulometría 2,2-4 mm presentan una mayor absorción acústica dentro del rango de frecuencia estudiado (400-3500 Hz). Con el incremento de espesor y mayor porcentaje de caucho de grano grueso el panel multicapa mejora su coeficiente de absorción.Este trabajo forma parte del Proyecto de Investigación PAID-06-11, dentro del plan de I+D+i financiado por la Universitat Politècnica de València.Segura Alcaraz, JG.; Crespo Amorós, JE.; Juliá Sanchis, E.; Nadal Gisbert, AV.; Gadea Borrell, JM. (2014). Estimación de la absorción acústica de paneles fabricados con neumáticos reciclados. DYNA: Ingeniería e Industria. 89:106-111. https://doi.org/10.6036/5796S1061118

Propiedades acústicas de láminas multicapa a partir de residuos de neumático

[ES] En este trabajo se realiza un estudio de la absorción acústica de paneles multicapa conformados a partir de materiales provenientes de neumáticos reciclados (GTR´s), tratando de dar una repuesta al problema medioambiental generado por estos residuos. El artículo se enmarca como un primer paso para la evaluación de la absorción acústica de estos nuevos paneles multicapa para su aplicación como barreras acústicas, insonorización de maquinaria y equipos industriales, acondicionamiento acústico de recintos, etc. Se han preparado dos tipos básicos de paneles multicapa con 10 y 20 mm de espesor. Cada panel multicapa está constituido por tres capas de diferentes espesores siempre con la disposición fibra-caucho-fibra. Para determinar el coeficiente de absorción se ha utilizado el método del tubo de impedancia acústica. Para el caucho se ha trabajado con granulometrías de entre 0,7 y 2,2-4 mm. Los resultados demuestran que los paneles multicapa con caucho de granulometría 2,2-4 mm presentan una mayor absorción acústica dentro del rango de frecuencia estudiado (400-3500 Hz).Este trabajo forma parte del Proyecto de Investigación PAID-06-11, dentro del plan de I+D+i financiado por la Universitat Politècnica de València.Segura Alcaraz, JG.; Crespo Amorós, JE.; Juliá Sanchis, E.; Nadal Gisbert, AV.; Gadea Borrell, JM.; Delgado, A. (2013). Propiedades acústicas de láminas multicapa a partir de residuos de neumático. Compobell, S.L. http://hdl.handle.net/10251/74079