1、FORD LABORATORY TEST METHOD BV 160-03 2001 O925 MEASUREMENT OF “ACOUSTICAL PERFORMANCE“ OF SOUND-DEADENING MATERIALS Revised Editorial - no technical change A. Cockman Application This procedure is used to determine the “Acoustical Performance“ of sound-deadening materials under simulated vehicle bo
2、dy conditions, in the 1 O0 - 10,000 Hz frequency range. Apparatus Required Test Apparatus - Apamat II - refer to Figure 1 The test material is applied to the test panel which is positioned in the clamping device. The “noise source chamber“ contains steel balls which are projected against the test pa
3、nel. The impact of the steel balls, and the air turbulence in the chamber causes the test panel to emit various harmonic vibrations. The noise emitted from the test panel is picked up by a microphone placed in the “receiver room“. The acoustic conditions in this chamber are equivalent to those found
4、 in an average vehicle. The definition of “Acoustical Performance“ is given as the difference in the noise spectrum between an uncoated and coated test panel. The Apamat II consists basically of: The Clamping Device A The Noise Source Chamber B The Receiver Room C Source: Inter-Keller A.G. Zurich, S
5、witzerland Measuring Instrument - refer to Figure 2 Consists of: The Spectrometer - type 21 12 - D Recorder - type 2305 - E Source: Bruel & Kjaer A.G. Copenhagen, Denmark I I Date I Action I Revisions I 1990 0627 I Copynght02001, Ford Global Technologies, Inc FORD LABORATORY TEST METHOD BV 160-03 Ma
6、terials Required Test Panel Material - Steel Body Skin Panels - clean and degreased. Surface Finish - 0.9 - 1.8 micro m C.L.A. Dimensions - 840 +/- 0.5 mm x 840 0.5 mm x 0.8 +/- 0.05 mm. Unless otherwise required by the applicable Engineering Material Specification Conditioning and Test Conditions A
7、ll test values indicated herein are based on material conditioned in a controlled atmosphere of 23 +/- 2 OC and 50 +/- 5 % relative humidity for not less than 24 h prior to testing and tested under the same conditions unless otherwise specified. Procedure To determine the acoustical performance of a
8、 material, the following must be measured on the same panel: a. The noise spectrum of an uncoated test panel. b. The noise spectrum of a test panel coated with the material under test. The acoustical performance of the material is then given by the difference in dB (decibels) between the noise spect
9、rum of the coated panel and the uncoated panel at specific frequencies in Hz (Hertz). 1. The closed container of sound-deadening material shall be conditioned for 24 h minimum at 23 +/- 2 OC prior to application. 2. The uncoated test panel is placed in the Clamping Device (A), and the drawer closed.
10、 3. The noise source chamber (B) is lifted to contact the receiver room (C) so that the acoustical insulation between noise source, test panel and the receiver room is completed. 4. Connect the microphone output of the Apamat to the spectrometer (D) and the recorder (E), refer to Figure 2, and switc
11、h on. 5. Switch on the exciter. The damping is set to 100 dB sound level by the meter range of the spectrometer. The recorder automatically picks up the noise spectrum between 1 O and 10,000 Hz. It is recorded at each 1/3 octave in this range. Refer to Figure 3, Curve a. 6. Remove the uncoated test
12、panel from the apparatus. Page 2 of 8 Copynght02001, Ford Global Technologies, Inc FORD LABORATORY TEST METHOD BV 160-03 7. Cut a specimen 840 +/- 0.5 mm x 840 +/- 0.5 mm from the sound-deadening material under test. (This must be one complete piece in order not to affect the acoustical performance
13、of the material). Apply the sound deadening specimen to the uncoated test panel by the normal manufacturing process (.e., by bonding, heat fusion or clamping). 8. Repeat steps 1 - 4, ensuring that test assembly is placed n the drawer with deadener material surface uppermost. 9. Record the noise spec
14、trum for the coated test panel on the same graph as the one used for the uncoated panel but using a different colored ink. A graph similar to that shown in Figure 3, Curve b is obtained. Note: The signal from a high efficiency damping material is too weak for the recorder, in which case it falls bel
15、ow the lower limit of the apparatus (under 60 dB). In this case, the meter range is adjusted on the spectrometer, .e., the range is reduced by 20 dB (see point A or B - Figure 3). Evaluation 1. From Figure 3, the logarithmic values are plotted for both spectra in each 1/3 Octave band as a function o
16、f frequency. The difference between the curves in dB gives the acoustical performance of the sound-deadening material. 2. A further curve (Figure 5) is established to indicate the quality of the sound-deadening material by plotting the difference between the uncoated test panel values and the coated
17、 test panel values against the frequency (Hz). 3. Compare the curve obtained in Para 2 with the curve given in the applicable Engineering Material Specification. Report whether minimum performance is obtained. Chemicals, materials, parts, and equipment referenced in this document must be used and ha
18、ndled properly. Each party is responsible for determining proper use and handling in its facilities. Page 3 of 8 Copynght02001, Ford Global Technologies, Inc FORD LABORATORY TEST METHOD BV 160-03 MEASUREMENT OF “ACOUSTICAL PERFORMANCE“ OF SOUND-DEADENING MATERIALS APAMAT II Figure 1 Page 4 of 8 Copy
19、nght02001, Ford Global Technologies, Inc FORD LABORATORY TEST METHOD BV 160-03 MEASUREMENT OF “ACOUSTICAL PERFORMANCE“ OF SOUND-DEADENING MATERIALS METER MICROPHONE Figure 2 Page 5 of 8 Copynght02001, Ford Global Technologies, Inc FORD L -BOWTORY TEST METHOD BV 160-03 MEASUREMENT OF “ACOUSTICAL PERF
20、ORMANCE“ OF SOUND-DEADENING MATERIALS 5000 10000 20 50 1 O0 200 500 1000 2000 3a 3b 124 - 40 -* d0 dB Figure 3 Page 6 of 8 Copynght02001, Ford Global Technologies, Inc FORD LABORATORY TEST METHOD BV 160-03 MEASUREMENT OF “ACOUSTICAL PERFORMANCE“ OF SOUND-DEADENING MATERIALS I O0 200 500 I O00 2000 5
21、000 I O000 Figure 4 Page 7 of 8 Copynght02001, Ford Global Technologies, Inc FORD LABORATORY TEST METHOD BV 160-03 MEASUREMENT OF “ACOUSTICAL PERFORMANCE“ OF SOUND-DEADENING MATERIALS 55 50 45 40 35 30 25 20 15 10 5 0 100 200 500 1 O00 2000 5000 1 O000 Figure 5 Page 8 of 8 Copynght02001, Ford Global Technologies, Inc
