Experimental findings on the underwater measurements uncertainty of speed of sound and the alignment system

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1 Journal of Physis: Conferene Series PAPER OPEN ACCESS Eperimental findings on the underwater measurements unertainty of speed of sound and the alignment system To ite this artile: T Q Santos et al 2016 J. Phys.: Conf. Ser View the artile online for updates and enhanements. This ontent was downloaded from IP address on 19/06/2018 at 00:25

2 Eperimental findings on the underwater measurements unertainty of speed of sound and the alignment system T Q Santos, A V Alvarenga, D P Oliveira, R C Mayworm, R M Souza, R P B Costa- Féli Laboratory of Ultrasound (Labus), Diretory of Sientifi and Industrial Metrology (Dimi), National Institute of Metrology, Quality and Tehnology (Inmetro), Av. Nossa Sra. das Graças 50, Duque de Caias, RJ, Brazil, ZIP taynara.qs@gmail.om Abstrat: Speed of sound is an important quantity to haraterize referene materials for ultrasoni appliations, for instane. The alignment between the transduer and the test body is an key ativity in order to perform reliable and onsistent measurement. The aim of this work is to evaluate the influene of the alignment system to the epanded unertainty of suh measurement. A stainless steel ylinder was previously alibrated on an out of water system typially used for alibration of non-destrutive bloks. Afterwards, the ylinder was alibrated underwater with two distint alignment system: fied and mobile. The values were statistially ompared to the out-of-water measurement, onsidered the golden standard for suh appliation. For both alignment systems, the normalized error was less than 0.8, leading to onlude that the both measurement system (under- and out-of-water) do not diverge signifiantly. The gold standard unertainty was 2.7 m s -1, whilst the fied underwater system resulted in 13 m s -1, and the mobile alignment system ahieved 6.6 m s -1. After the validation of the underwater system for speed of sound measurement, it will be applied to ertify Enapsulated Tissue Mimiking Material as a referene material for biotehnology appliation. 1. Introdution Speed of sound is an important quantity to haraterize materials in ultrasoni appliations. The aurate measurement of suh property is a key step to ertify referene materials used for alibrations in ultrasound field. The Inmetro s Laboratory of Ultrasound (Labus) has developed systems to alibrate the speed of sound of different materials (solids and liquids) [1][2][3], whih are ontinually evaluated on metrologial bases, and upgraded to improve the measurement unertainty. The implementation of new measurement proedure depends on their validation, and the guidelines for validating are presented in DOQ-CGCRE-8 [4]. Those guidelines are appliable to non-standard methods, standardized methods used outside of its original sope, methods modified to meet speifi requirements, and new methods developed by the laboratory. This artile reports the improvement of the speed of sound measurement system developed at Labus/Inmetro. The new setup has more degrees of freedom in the mounting used to align the sample under test. The model to estimate the measurement unertainty is presented and the obtained results are ompared with a standardized method. The validate measurement system will be applied to ertify the speed of sound of Enapsulated Tissue Mimiking Material (ETMM) for biotehnology appliation. 2. Methodology The test body used in this work was an AISI 304 stainless steel ylinder (Figure 1), mahined and polished to a surfae roughness finishing better than 0.8 µm (Ra). Its thikness was alibrated using a aliper rule, and the result used as referene value (101.4 mm; u = 0.1 mm; k = 2.02; p = 0.95). Its Content from this work may be used under the terms of the Creative Commons Attribution 3.0 liene. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal itation and DOI. Published under liene by Ltd 1

The alibrated speed of sound was defined as referene value ( = 5724.7 m s -1 ; u = 2.7 m s -1 ; k = 1.96; p = 0.95). Figure 1. Stainless steel AISI 304 test body.

3 diameter is 100 mm, and no alibration is needed for this dimension in the present work. The longitudinal speed of sound was measured in the entral region of the test body, using the system desribed in [1], developed aording to the standard ABNT-NBR 15824:2010 [5]. The alibrated speed of sound was defined as referene value ( = m s -1 ; u = 2.7 m s -1 ; k = 1.96; p = 0.95). Figure 1. Stainless steel AISI 304 test body. The new measurement system is omposed of two ultrasoni transduers (T1 and T2), ating as a transmitter or reeiver at different stages of the method, both with nominal entral frequeny of 5 MHz (Model v303, Panametris, Olympus, MA, USA). The transduers and the test body were mounted on a mehanial system onstruted to ensure their fiation and alignment. The transmitter transduer is mounted in a positioning with five degrees of freedom, while the reeiver transduer and the test body are mounted on two degrees of freedom positioning system (Figure 2). All measurement system is immersed in a water tank filled with deionized water, and at least 30 min are neessary to ahieve the thermal equilibrium before start the measurements. Here, it is important to highlight that the previous system set at Labus/Inmetro had only two degrees of freedom at reeiver transdues, while the transmitter transduer and the test body were kept fied (details in [3]). An arbitrary funtion generator (33250A Agilent Tehnologies, CA, USA) is used to drive the transmitter transduer with a 20-yles sine burst at 5 MHz, and 20 V peak to peak. The repetition period is defined as 10 μs. The signals aquired by the reeiver transduer are digitized using the osillosope DSO 5012A (Agilent Tehnologies, CA, USA) with a sampling frequeny of 500 MSa s -1. B D A C F E Figure 2. Eperimental set-up for aousti measurement. A, transmitting transduer with five degrees of freedom; B, reeiver transduer with two degrees of freedom; C, speimen; D, osillosope; E, signal generator; F, omputer. 2

4 The temperature was monitored throughout the measurements with a thermometer (Thermosheneider, Baden-Württemberg, Germany). The whole proedure was repeated five times by two distint operators in intermediate preision ondition of measurement. Different flight times are determined and are alled here: (refletion at the test body fae nearest to the transmitter transduer), (refletion at the test body fae far of the transmitter transduer), (transmission between transmitter and reeiver transduers with the test body in the aousti path) and (transmission between transmitter and reeiver transduers without the test body). The longitudinal speed of sound [m/s] was alulated by (1). = (1) where, is the thikness of the test body in alulated from (2), and t [s] is the time of flight of ultrasound in the test body alulated from (3). = (2) = ( + ) (3) The ultrasound propagation veloity in water [m/s] is alulated aording to (4) [6]. =, +,, (4) Where, T [ C] is the temperature in water. The measurement unertainty is estimated aording to the guide to the epression of unertainty in measurement [7]. The following soures of unertainty were onsidered in measuring the speed of sound, as well the test body thikness: type A evaluation determined as the standard deviation between the five repetitions of the test; type B evaluation of the temperature obtained from the thermometer alibration ertifiate (0.03ºC); type B evaluation of the ultrasound propagation speed in water (0.018 m s -1 ) [6]; type B evaluation of the time base used to determine different times of flight from the osillosope alibration ertifiate (0.06%). The epanded unertainty was alulated for a overage probability of In this work, the benhmark is the normalized error ( ) between the referene values, determined using the standardised measurement method, and the results ahieved using the previous measurement system [3] and the improved one presented here. The results are onsidered satisfatory if. 3. Results The results of speed of sound and thikness determined using the measurement system presented here (mobile system) and the previous system desribed in [3] (fied system) are presented on Table 1 and Table 2, for operator 1 and 2 respetively. One an observe that the results of thikness and speed of sound ahieved using both systems when ompared with the respetive referene values presented 1. This result suggests that both methods an be onsidered validate for measuring the speed of sound, as well as the thikness of test bodies. 3

5 Table 1. Results of thikness () and speed of sound () ahieved by operator 1 (Op. 1) using fied and mobile systems. Op. 1 Fied Mobile Average Value k U En Table 2. Results of thikness () and speed of sound () ahieved by operator 2 (Op. 2) using fied and mobile systems. Op. 2 Fied Mobile Average Value k U En However, one an pereive that the speed of sound epanded unertainties, ahieved using the mobile system, are lower than the one obtained with the fied system, for both operators. This result indiates that inreasing the degrees of freedom in the system allowed a better alignment between the two ultrasoni transduers (transmitter and reeiver), as well as between them and the test body, diretly affeting the redution of unertainty. 4. Disussion and Conlusion In literature, there are referenes mentioning speed of sound results for different materials [8][9]. However, rarely authors give attention to metrologial rigors in their studies, or do not properly report their unertainty results. Sometimes unertainty is mistakenly onfused with error or standard deviation and, when presented, the validation of measurement method is not detailed, neither it is eplained how the unertainties were alulated. This work presented the validation of a new measuring system to determine the speed of sound of test bodies. The measuring system was first validated at 5 MHz, and new validation will be arried out onsidering other frequenies. The presented measuring system will be applied for ertifying an Enapsulated Tissue Mimiking Material (ETMM) as a referene material for biotehnologial appliations. Referenes [1] Maggi L E, Silva C E R, Alvarenga A V, Costa-Feli RPB Ultrasoni alibration and ertifiation of V1 and V2 type referene standard bloks for use in Non-Destrutive Testing Journal of Physis: Conferene Series doi: / /279/1/

6 [2] Figueiredo M K K, Costa-Féli R P B, Alvarenga A V, Maggi L E, Romeiro G A 2012 Fuel [3] Santos T Q, Oliveira D P, Costa-Féli R P B, Alvarenga A V 2014 Validação do método de medição da veloidade ultrassônia de propagação longitudinal XXIV Congresso Brasileiro de Engenharia Biomédia CBEB [4] INMETRO. DOQ-CGCRE-008: Orientações sobre validação de métodos analítios ª revisão, INMETRO: Duque de Caias [5] Assoiação Brasileira de Normas Ténias Ensaios não-destrutivos - Ultrassom - Medição de espessura 2010 ABNT NBR [6] Lubbers J and Graaff R 1998 A simple and aurate formula for the sound veloity in water Ultrasound in Med. and Biol. 24 (7) [7] JCGM 2008 Evaluation of Measurement Data Guide of the Epression of Unertainty in Measurements [8] Cannon L M, Fagan A J and Browne J E 2011 Novel tissue mimiking materials for high frequeny breast ultrasound phantoms Ultrasound in Mediine and Biology, 37(1) [9] Brewin M P, Pike L C, Rowland D E and Birh M J 2008 The aousti properties entered on 20 MHz, of IEC agar-based tissue mimiking materials and its temperature, frequeny and age dependene Ultrasound in Mediine and Biology 34 (8) Aknowledgments Researh reported in this paper has been partially funded by the Carlos Chagas Filho Researh Support Foundation (FAPERJ), Grant Numbers E-26/ /2013 and E-26/ /2014, and from the National Counil for Sientifi and Tehnologial Development (CNPq), Grant Number /

Experimental findings on the underwater measurements uncertainty of speed of sound and the alignment system

Experimental findings on the underwater measurements uncertainty of speed of sound and the alignment system Eperimental findings on the underwater measurements unertainty of speed of sound and the alignment system T Q Santos 1, A V Alvarega 1, D P Oliveira 1, R C Mayworm 1, R M Souza 1, R P B Costa-Féli 1 1