Cuantificación de la radiación de la estructura en sistemas de caja cerrada

En el presente trabajo se ha realizado una contribución al estudio de la cuantificación de la radiación de las paredes de la estructura en sistemas de caja cerrada, estableciendo una relación de la respuesta vibroacústica de este tipo de sistemas radiantes con las características del material de construcción, tales como el modulo de Young, el amortiguamiento, o la densidad. Para abordar el problema se plantea el acople mecano-acústico entre los diferentes elementos del sistema radiante. Idealmente, en los sistemas radiantes compuestos de altavoces montados sobre un recinto acústico o caja, las paredes de la caja deberían de ser infinitamente rígidas y con movimiento nulo. Sin embargo, en la realidad la experiencia demuestra que las paredes se comportan como placas vibrantes bajo la acción de las presiones interiores y contribuyen a la radiación final de sonido del sistema, sobre todo en el rango de las bajas frecuencias. Para conseguir el objetivo propuesto, en primer lugar se han realizado una serie de medidas experimentales sobre unos modelos de caja cerrada con y sin altavoz. En la fase experimental se ha estudiado el comportamiento vibracional de las paredes de la estructura mediante análisis modal y medidas de vibración, y la respuesta sonora del sistema altavoz, aire interior y estructura, acoplado mediante medidas de presión e intensidad acústicas. A continuación, y en base a los resultados experimentales, se han implementado unos modelos numéricos de un sistema altavoz, aire interior y estructura. Se concluye que la estructura colorea la respuesta sonora del sistema en todo el rango de frecuencia estudiado, debido a resonancias o vibraciones forzadas de la misma.Segura Alcaraz, JG. (2009). Cuantificación de la radiación de la estructura en sistemas de caja cerrada [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/4343Palanci

The effect of the combination of multiple woven fabric and nonwoven on acoustic absorption

[EN] Textile materials can be used as acoustic materials. In this study, the acoustic absorption coefficient of multilayer fabrics with 60 ends/cm and 15, 30, 45, and 60 picks/cm is measured when the fabric is added as a resistive layer on top of a polyester nonwoven, in order to study the influence of the fabric spatial structure in the acoustic absorption of the assembly. Five different fabric structures are used. Design of experiments and data analysis tools are used to describe the influence of two manufacturing factors on the sound absorption coefficient of the ensemble. These factors are the fabric weft count (picks/cm) and the thickness of the nonwoven (mm). The experimental conditions under which the maximum sound absorption coefficient is achieved are found. The influence of each factor and a mathematical model are obtained. Results of statistical and optimization analysis show that for the same fabric density, sound absorption coefficient increases as the number of layers decreases.Segura-Alcaraz, P.; Segura Alcaraz, JG.; Montava-Seguí, I.; Bonet-Aracil, M. (2021). The effect of the combination of multiple woven fabric and nonwoven on acoustic absorption. Journal of Industrial Textiles. 50(8):1262-1280. https://doi.org/10.1177/15280837198587711262128050

Textiles in architectural acoustic conditioning: a review

[EN] Environmental noise is a problem of increasing interest in advanced societies. Different types of textiles have properties which are suitable for the construction of elements able to condition sound in rooms. The use of these elements can foster acoustic comfort in all kind of rooms, both public and private. This work is a review of the possibilities and trends of textile materials in the field of acoustic conditioning. The use of textile materials for acoustic conditioning is widely extended. On the other hand, many efforts have been done in the last decades to understand the sound absorption mechanisms and to design materials and devices able to customize the sound space. Many of these new developments have used materials like wood, metal, plastic. Textiles can be thought as fully designable materials and potential base of composites, providing their unique technical and aesthetical characteristics to any ensemble.Segura Alcaraz, MP.; Bonet-Aracil, M.; Juliá Sanchis, E.; Segura Alcaraz, JG.; Montava-Seguí, I. (2022). Textiles in architectural acoustic conditioning: a review. Journal of the Textile Institute. 113(1):166-172. https://doi.org/10.1080/00405000.2021.1976483166172113

Optimisation of the sound absorption of a textile material

[ES] Un material absorbente de sonido de tipo fibroso como la guata de poliéster se puede cubrir con una lámina de tejido para su protección y decoración, mejorando sus características de absorción acústica. En este trabajo se mide el coeficiente de absorción de sonido de un material textil multicapa formado por una capa de 45 mm de no tejido de poliéster y una capa de tejido acolchado empleando el tubo de impedancia. Se emplea el diseño de experimentos para optimizar dos características del tejido como son la densidad de trama y el empleo de tramas de relleno de forma que se obtenga el mayor coeficiente de absorción de sonido en todas las frecuencias estudiadas. Los resultados proporcionan la combinación de los factores estudiados que maximiza la absorción acústica.[EN] A fibrous sound absorbing material, such as a polyester nonwoven, can be covered with a layer of fabric for its protection and decoration, with an improvement of its sound absorption characteristics. In this work, the sound absorption coefficient of a multilayer textile material composed by a 45mm polyester nonwoven and a layer of stuffed fabric, is measured using an impedance tube. Design of experiments is used to optimize two characteristics of the fabric like weft density and use of stuffing picks, so the highest sound absorption coefficient is obtained in all the studied frequencies. Results show the combination of the studied factors that maximizes sound absorption.Segura-Alcaraz, P.; Segura Alcaraz, JG.; Montava-Seguí, I.; Bonet-Aracil, M. (2020). Optimización de la absorción de sonido de un material textil. DYNA Ingeniería e Industria (Online). 95(3):313-316. https://doi.org/10.6036/9570S31331695

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

Sustainable multiple resonator sound absorbers made from fruit stones and air gap

[EN] This article investigates the sound absorption coefficient of materials manufactured from natural wastes. Fruit stones from some crops are one of the most available natural wastes in the Mediterranean Region. Recycled and vegetable products are becoming an interesting alternative to traditional materials to be used as sound-absorbing panels. Fruit stones can be profitable for a number of applications, such as biomass to produce energy. This research work intends to demonstrate that one of their applications can be ecological sound absorbers in building acoustics. Different four fruit stone samples, with different air gap volume percentages, display similar behaviour to multiple Helmholtz resonators (MHRs). By adding a 40 mm-thick rockwool layer, the sound absorption coefficients are compared for each sample. The experimental results allow establishing some analogies between MHRs and the new absorbing materials according to thickness, fruit type and the air gap volume. These fruit stones have been demonstrated as a good choice from acoustic and sustainable points of view.Juliá Sanchis, E.; Segura Alcaraz, JG.; Montava-Belda, I.; Gadea Borrell, JM. (2022). Sustainable multiple resonator sound absorbers made from fruit stones and air gap. Alexandria Engineering Journal. 61(12):10219-10231. https://doi.org/10.1016/j.aej.2022.03.0631021910231611

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

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