TechnicalNotes TableTable2 AcousticPropertiesofMaterialsNearFieldDistanceofFlatTransducersinWater LongitudinalShearAcoustic ElementFocalLength(PTF) Material FrequencyN VelocityVelocityImpedance Diameter MinMax 26 (in/ms)(m/s)(in/ms)(m/s)(Kg/msx10) (MHz)(inches)(inches)(inches)(inches) ? Acrylicresin(Perspex)0.1072,7300.0561,4303.22 1.504.7572.153.80 Aluminum0.2496,3200.1233,13017.06 1.1252.6611.502.10 0.5 Beryllium0.50812,9000.3508,88023.5 1.002.0951.251.65 Brass,naval0.1744,4300.0832,12037.30 0.751.1640.780.93 Cadmium0.1092,7800.0591,50024.02 1.509.5592.507.65 Columbium0.1944,9200.0832,10042.16 1.1255.3661.904.30 Copper0.1834,6600.0892,26041.61 1.01.004.2351.6253.38 Glycerine0.0761,920——2.42 0.752.3721.001.90 Gold0.1283,2400.0471,20062.60 0.501.0430.600.80 ? Inconel0.295,8200.1193,02049.47 1.5021.5342.7014.50 Iron0.2325,9000.1273,23045.43 1.12512.0992.159.50 Iron,cast 1.009.5541.8757.60 (slow)0.1383,5000.0872,20025.00 2.250.755.3641.004.30 (fast)0.2205,6000.1263,22040.00 0.502.3740.801.90 Lead0.0852,1600.02870024.49 0.3751.3290.501.06 Manganese0.1834,6600.0932,35034.44 0.250.5840.350.45 Mercury0.0571,450——19.66 1.0014.8681.9511.5 Molybdenum0.2466,2500.1323,35063.75 0.758.3501.006.65 MotorOil(SAE20or30)0.0691,740——1.51 3.50.503.6990.832.95 Nickel,pure0.2225,6300.1172,96049.99 0.3752.0730.601.65 Platinum0.1563,9600.0661,67084.74 0.250.9140.3850.70 ? Polyamide,(nylon,Perlon) 1.0021.2431.9514.40? (slow)0.0872,2000.0431,100.40 0.7511.9321.009.50 (fast)0.1022,6000.0471,2003.10 5.00.505.2870.754.20 Polystyrene0.0922,340——2.47 0.3752.9650.602.35 Polyvinylchloride,PVC,hard0.0942,3950.0421,0603.35 0.251.3090.431.00 Silver0.1423,6000.0631,59037.76 0.7517.9001.0012.75? 7.5 Steel,10200.2325,8900.1283,24045.63 0.507.9330.756.30? Steel,43400.2305,8500.1283,24045.63 1.0042.4902.0020.00? Steel,3020.2235,6600.1233,12045.45 0.7523.8681.0015.375? austeniticstainlessSteel,3470.2265,7400.1223,09045.40 100.5010.5790.758.40? austeniticstainlessTin0.1313,3200.0661,67024.20 0.3755.9340.604.75? Titanium,Ti150A0.2406,1000.1233,12027.69 0.252.6220.462.10 Tungsten0.2045,1800.1132,87099.72 0.5015.8700.7511.75? Uranium0.1333,3700.0781,98063.02 150.3758.9020.607.10? Water(20°C)0.0581,480——1.48 0.253.9350.503.15? Zinc0.1644,1700.0952,41029.61 0.255.2470.504.20? 20 Zirconium0.1834,6500.0892,25030.13 0.1251.2900.251.00? -5 250.256.5590.505.25? ConversionFactor:1m/s=3.937x10in/μS Source:NondestructiveTestingHandbook2ndEditionVolume7 Panametrics’StandardCaseStyle,LargeDiameterCaseStyle,SlimLineCaseStyle,andPencil UltrasonicTestingASNT1991edPaulMcIntire CaseStyleImmersionTransducerswithstraightconnectors(seepages20-24)canbefocusedbetween theMinimumandMaximumPointTargetFocal(PTF)distancelimitslistedinTable2.Pleaseconsult Panametricsbeforeorderingatransducerfocusedoutsidetheselimits. NearFieldDistancesofFlatTransducersinWater Thenearfieldvaluesinthistablehavebeendeterminedusingthefollowing ?Considerationshouldbegiventoattenuationeffectswhichincreaselinearityandwiththesquare equation: offrequencyandthesquareofbandwidth.Inapplicationswherelongwaterpathsarerequiredthe effectsoffrequencydependentattenuationshouldbecheckedperASTME1065AnnexA7.Itis advisabletoconsidertheeffectsoffrequencydependentattenuationifthefocaldistanceequalsor exceedsthefollowingvalues: FrequencyFocalLength Notethatequations8and8aonpage42werederivedfromthis MHzinches expression.Thecalculationswerecarriedoutassuminganultrasonic 5 velocityinwaterof0.586x10in/secat22°Candusingtheactual 5.013 transducerelementdiameters.Itshouldbenotedthattheactualtransducer 7.56 elementdiametersareslightlysmallerthanthenominalelementdiameters 103.5 listedinthetablesinthecatalog. 151.5 Theminimumandmaximumpracticalfocallengthshavebeencalculatedby 200.8 consideringtheacousticandmechanicallimitationsofeachconfiguration. 250.5 Theselimitationsareafunctionoftransducerfrequency,elementdiameter, 300.4 andcasedimensions.Theremaybeexceptionstothelimitslistedinthe table. 48www.olympusNDT.com |
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