ANSI S2.22-1998 pdf download Resonance Method for Measuring the Dynamic Mechanical Properties of Viscoelastic Materials
4.7 Computer A computer is required to automate the data ac- quisition and analyses. The computer should be easy to program and operate.
5 Operating procedures
5.1 Sample preparation and mounting Mold test specimens into the shape of a bar. The mold shall be at least 150 mm long, with square lateral dimensions of 6.35 mm, + O mm, -0.13 mm. Trim the molded specimen of all flash and cut to a length of 1 02 mm 2 1 3 mm, using a razor blade. Square the ends of the bar by machining. After machining, the bar shall be able to stand upright on either end without support. Square ends are required to obtain a good bond between the test specimen and mounting blocks.
NOTES 1 A circular cross-section of about 6.35 mm diameter is also acceptable instead of a square bar. 2 Lengths no less than one-half the 102 mm speci- fied or no more than twice that length are also ac- ceptable. Shorter lengths produce resonances at higher frequencies and can lead to fewer peaks being observed due to higher absorption at higher frequencies. Longer lengths produce resonances at lower frequencies and can lead to problems due to bending of the longer specimen. Three properties of the specimen, required in the analyses, shall be measured before bonding the specimen to the mounting blocks. Determine, by a micrometer, the length in meters to four significant digits. Determine, by a balance, the mass of the = OLöL4 4 0 0003808 7b4 I ANSI S2.22-1998 specimen in kilograms to four significant digits. De- termine the density of the specimen in kg/m3 by a water displacement technique.
NOTE – A method such as ASTM D 792, Standard Test Method for Specific Gravity and Density of Plastic by Displacement [l], is acceptable. At the shaker end (figure 1) of the specimen, bond the specimen and one accelerometer by adhesive to the mounting block. The mounting block is steel with dimensions of 25 x 19 x 1 3 mm. Both rigid epoxy and cyanoacrylate adhesives are acceptable.
NOTE-It has been shown [2] that the adhesive thickness shall be less than 0.5 mm and the modulus of the adhesive shall be greater than that of the ma- terial to be measured. Under these conditions, the adhesive does not affect the measurements. Bond the second accelerometer to the accelerometer mounting block (figure l), which is then bonded to the specimen. Use the same adhesive for bonding as used previously. The accelerometer mounting block is a cube, 6.35 mm on each side.
NOTES 1 The purpose of the accelerometer mounting block is to avoid the wear and tear of repeatedly bonding and de-bonding the accelerometer to the specimen. In the arrangement specified in this Standard, the accelerometer is bonded to one side of the mounting block and remains there. The other end of the block is de-bonded and re-bonded each time a new specimen is mounted. 2 A small accelerometer mounting block is desir- able to minimize creep in the sample. While the block shall be the same cross-sectional area as the accelerometer, it is acceptable for the block to be shorter than above, but no longer.