FORD FLTM EU-BV 060-1-2000 DETERMINATION OF STRUCTURE BORNE NOISE DAMPING BY SOUND DEADENING MATERIALS.pdf

1、 FORD LABORATORY TEST METHOD EU-BV 060-01 Date Action Revisions 2000 12 08 Revised Editorial no technical change A. Cockman 1994 02 28 Printed copies are uncontrolled Page 1 of 6 Copyright 2000, Ford Global Technologies, Inc. DETERMINATION OF STRUCTURE BORNE NOISE DAMPING BY SOUND DEADENING MATERIAL

2、S Application This method is used to determine the damping of structure borne noise by sound deadening materials. This method is applicable for materials up to a thickness of 2.5 mm. Apparatus Required Test Equipment See drawings. Test Panel Surface roughness 0.9 - 1.8 micrometre C.L.A, dimensions 6

3、00 x 30 x 1 mm. The weight of the test panel must be 140 +/- 2 g. Excitation and Measuring Device (see diagram) *Beat frequency oscillator Type 1017 *Microphone amplifier Type 2603 *Recorder Type 2305 *Exciter Type MM 0002 *Pick-up Type MM 0002 *Source: Bruel & Kjaer AG Copenhagen Denmark Mechanical

4、 Convection Oven Capable of maintaining temperatures up to 200 +/- 2 C. Cold Box Capable of maintaining temperature down to - 40 +/- 1 C. Note: Both the mechanical convection oven and the cold box must be large enough to accommodate the test equipment with the test panel. Basic Theory The damping fa

5、ctor characteristics (structure born noise) is known as the loss factor Z. It is proportional to the deformation work energy converted to heat per cycle. For coated sheet metals the resonance method is used to determine the loss factor . FORD LABORATORY TEST METHOD EU-BV 060-01 Page 2 of 6 Copyright

6、 2000, Ford Global Technologies, Inc. For a resonance frequency fo, the two frequencies f1 and f2 are determined whereby f1 fo f2 and the amplitudes are lower by the factor A/2 and where A is the max amplitude of fo. It is f2 - f1 = f f is the band width of the resonance frequency. The loss factor i

7、s = f 2 - f 1 = f F0 f0 For quality comparison purposes in the automotive industry the loss factor at 200 Hz is a function of the material weight and the total weight. Conditioning and Test Conditions All test values indicated herein are based on material conditioned in a controlled atmosphere of 23

8、 +/- 2 C and 50 +/- 5 % relative humidity for not less than 24 h prior to testing and tested under the same conditions unless otherwise specified. Procedure Preparation of Test Assemblies A minimum of 3 test assemblies for each material should be prepared. 1. Prepare test panels in accordance with r

9、equirements of the relevant material specification and accurately weigh to 0.1 gf (G1). FORD LABORATORY TEST METHOD EU-BV 060-01 Page 3 of 6 Copyright 2000, Ford Global Technologies, Inc. 2. Apply test material by one of the following methods as specified in the material specification. a. Adhesives

10、b. Spraying with subsequent air drying c. Spraying with subsequent heat drying d. Heat fusion 3. After coating and bonding to test panel the test assemblies are stored for 24 h at 23 +/- 2 C and then again weighed to 0.1 gf (G). 4. The ratio of the material weight to the total weight in % is determi

11、ned as follows: Ratio % = G - G 1 x 100 G This ratio and the loss factor determine the quality of the test material. 5. The coating is then removed from one end of the test assembly for a length of 50 mm. Procedure for Measurement (see diagram) 1. The test assembly P is clamped with the removed coat

12、ing end into the head K of the test equipment such that the remaining 550 +/- 1 mm length is free to oscillate. 2. The excitation of vibration is transmitted over exciter D while the vibration level decay of the test assembly is taken up by the pick up E directly under the clamping area. Note: The t

13、est must be performed at a temperature of 20 +/- 2 C. If the relevant Material Specification requires test temperatures other than the afore mentioned, the test must be performed in a mechanical convection oven or in the cold box respectively. It must be ensured that the test assembly has attained t

14、est temperature before testing. Evaluation According to example on page 5. Chemicals, materials, parts, and equipment referenced in this document must be used and handled properly. Each party is responsible for determining proper use and handling in its facilities. FORD LABORATORY TEST METHOD EU-BV

15、060-01 Page 4 of 6 Copyright 2000, Ford Global Technologies, Inc. MEASURMENT MESSUNG G - G 1 f0 f1 f2 f = f2 f1 = f/f0 1 85 81 90 9 0.106 2 29.5 % 140 132 148 16 0.118 3 215 201 228 27 0.125 For exact determination of at 200 Hz the average values of f0 are entered into the graph as shown below and t

16、he loss factor determined from the curve at 200 Hz. FORD LABORATORY TEST METHOD EU-BV 060-01 Page 5 of 6 Copyright 2000, Ford Global Technologies, Inc. DETERMINATION OF STRUCTURE BORNE NOISE DAMPING BY SOUND DEADENING MATERIALS Diagram A. Beat Frequency Oscilator 1. Frequency Adjustment-Coarse B. Mi

17、crophone Amplifier 2. Maximum Reading-Coarse C. Recorder 3. Frequency Adjustment-Fine D. Exciter 4. Frequency Reading-Fine E. Pick Up 5. Regulator, Exciter Current K. Head of Test Equipment P. Test Assembly FORD LABORATORY TEST METHOD EU-BV 060-01 Page 6 of 6 Copyright 2000, Ford Global Technologies, Inc. DETERMINATION OF STRUCTURE BORNE NOISE DAMPING BY SOUND DEADENING MATERIALS The dimensions of the test equipment depend upon the size of the specified test assembly.