1、 WORLDWIDE ENGINEERING STANDARDS Test Procedure GMW16695 Sealer Compression Density Test Copyright 2012 General Motors Company All Rights Reserved June 2012 Originating Department: North American Engineering Standards Page 1 of 7 1 Scope Note: Nothing in this standard supercedes applicable laws and
2、regulations. Note: In the event of conflict between the English and domestic language, the English language shall take precedence. This procedure is used to determine the physical behavior of a sealer material under pressure conditions. The materials compressibility/rebound characteristics are deter
3、mined by this procedure. This test is of particular value for materials containing fragile filler components such as glass microspheres or plastic microspheres as the results can be used to predict the crush or damage to these components under hydrostatic pressure. 1.1 Purpose. A Johnstone Sep-Check
4、 test apparatus or equivalent (reference SAE J1864) is used to conduct this test. A sealed steel cylinder (of initial volume of 150.76 cc) is completely filled with material to be tested, loaded into the Sep-Check load frame and subjected to a progressive increase in loading upon the pressure cap. T
5、his load is applied in a manner which increases the internal hydrostatic pressure of the material by a measured increment (usually 13.8 bar/200 psi). Any displacement of the pressure cap is measured by means of a dial extensometer or Linear Voltage Displacement Transducer (LVDT). Two additional meas
6、urements are taken at each material pressure increment the air pressure in the loading cylinder (total applied load) and the displacement of the pressure cylinder cap (total compression). By calculating and plotting the material hydrostatic pressure against the percentage compression of the material
7、, a stress-strain plot for the material can be constructed and used to determine effective compressive modulus (resistance to compression) and filler yield point (failure limit of pressure sensitive filler components). Finally, the total material compression for a peak loading pressure can be separa
8、ted into rebound (elastic) and crush (permanent) compressive elements. 1.2 Foreword. Not applicable. 1.3 Applicability. This test procedure is applicable to “Ultralight Sealer Materials” approved under the following specifications: GMW16070, GMW16680 and GMW3017. 2 References Note: Only the latest a
9、pproved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. ASTM D1475 ASTM D2196 SAE J1524 SAE J1864 2.2 GM Standards/Specifications. GMW3017 GMW16070 GMW16680 2.3 Additional References. None. 3 Resources 3.1 Facilities. Not applicable. 3.2 Equipment. Referen
10、ce Appendix A, Figures A2 and A3. 3.3 Test Vehicle/Test Piece. Not applicable. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16695 Copy
11、right 2012 General Motors Company All Rights Reserved June 2012 Page 2 of 7 3.4 Test Time. Not applicable. 3.5 Test Required Information. Not applicable. 3.6 Personnel/Skills. Not applicable. 4 Procedure 4.1 Preparation. 4.1.1 Experimental Preparation - Equipment. 4.1.1.1 Connect the multi-stage cyl
12、inder to an air source and adjust the air pressure regulator so that there is no pressure supplied to the cylinder. Open the four-way hand valve to confirm that there is no pressure in the system. 4.1.1.2 Place the filled pressure cup assembly into the slot at the base of the stand. 4.1.1.3 Leaving
13、the hand valve open, slowly dial up the air pressure so that the piston of the multi-stage cylinder descends slowly until it comes into contact with the piston cap of the pressure cup assembly. Close the hand valve and dial air pressure to 0 bar/0 psi. 4.1.1.4 Set up the dial extensometer so that it
14、 is level and perpendicular to the displacement follower arm. Adjust the extensometer to indicate an initial displacement of 0.00 mm. 4.1.2 Running the Test. 4.1.2.1 Open the hand valve and slowly dial up the air pressure until the gage reads 13.8 bar (200 psi). 4.1.2.2 Close the hand valve and let
15、the cylinder equilibrate for 30 s. 4.1.2.3 Record the air pressure (bar and pounds per square inch (psi), material pressure (bar and psi) and dial extensometer displacement (millimeters). 4.1.2.4 Repeat steps 4.1.2.1 through 4.1.2.3 in 13.8 bar (200 psi) increments until the material pressure reache
16、s 330 bar (4500 psi). Record all data as called out in 4.1.2.3. 4.1.2.5 Slowly regulate the air pressure back to 0 bar/psi and let the pressure cup equilibrate for 300 s. Record the final displacement (material rebound step) in millimeters. 4.1.2.6 Perform a density cup measurement upon the compress
17、ed material to determine any increase in density and report in grams/cubic centimeter (g/cc) and pounds/gallon (lb/gal). 4.2 Conditions. Not applicable. 4.2.1 Environmental Conditions. Not applicable. 4.2.2 Test Conditions. Deviations from the requirements of this standard shall have been agreed upo
18、n. Such requirements shall be specified on component drawings, test certificates, reports, etc. 4.3 Instructions. 4.3.1 Compression Test Procedure. 4.3.1.1 Material. 4.3.1.1.1 Record the name of manufacturer, product ID code, batch/lot number and date of manufacture. 4.3.1.1.2 Determine the initial
19、viscosity of the material using a rheometer (ASTM D2196), and Castor Severs press flow (SAE J1524). Use the spindle, orifice and test parameters called out in individual material specification. Report rheometer results in centipoise, and press-flow results in seconds. 4.3.1.1.3 Perform a density mea
20、surement (ASTM D1475), report grams/cubic centimeter (g/cc) and pounds/gallon (lb/gal) on the material to determine an initial density before start of test. 4.3.1.2 Experimental Preparation Material. 4.3.1.2.1 Assemble complete pressure chamber (Johnstone Pressure Chamber 120-102 reference SAE J1524
21、 or equivalent). Install a 350 bar (5000 psi) pressure transducer, or a 350 bar pressure gauge (show pressure in BAR) into one of the in npt side ports. 4.3.1.2.2 Draw a 355 cc volume of test material into a Semco tube taking care not to introduce air. 4.3.1.2.3 Open the bleeder valve on the pressur
22、e cup container. 4.3.1.2.4 Push the piston cap to the bottom of the pressure cup container. 4.3.1.2.5 Remove the in pipe plug from the bottom of the pressure cup. Thread a in pipe nipple onto the Semco tube and dispense material until it flows out the nipple removing any residual air. Copyright Gene
23、ral Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16695 Copyright 2012 General Motors Company All Rights Reserved June 2012 Page 3 of 7 4.3.1.2.6 Thread
24、open end of in nipple into the pressure cup plug hole and fill the pressure chamber until material forces all residual air out of the bleeder hole. Close the bleeder valve. 4.3.1.2.7 Continue to fill the pressure cup until the piston cap reaches the top of the pressure cup. The internal volume of th
25、e filled pressure cup is 150.76 cc (9.2 in3). 4.3.1.2.8 Remove the in nipple and replace with a in inlet pipe plug. 4.3.1.2.9 Reopen the bleeder valve to relieve any excess material pressure and then close. 5 Data 5.1 Calculations. Not applicable. 5.2 Interpretation of Results. Not applicable. 5.3 T
26、est Documentation. 5.3.1 Data Calculations and Presentation. 5.3.1.1 For each material pressure measurement point, determine the degree of compression by the following formula: % compression = C/10. Where: C = the deflection as measured by the dial extensometer, 10 = is the initial length of the mat
27、erial column in the pressure cylinder (usually 97.54 mm (3.84 in). 5.3.1.2 Construct a plot of the Material Pressure (y) vs. % Compression (x) (see Figure A1). 5.3.1.3 Apply linear regression analysis to the initial portion of the pressure vs. compression curve. The slope of the regression function
28、can be considered to be the effective compressive modulus of the material. Effective compressive modulus allows the estimation of the amount of compression the material will exhibit under pressure in a dispensing system. This value can be used as a quantitative means of assessing the compressibility
29、 of different material systems. To obtain the Compressive Modulus value, divide the Material Pressure for each step by the % Compression for that step. Then sum all these values and divide by the number of steps (omitting the “zero-pressure” and “rebound” steps). The resulting value is the Compressi
30、ve Modulus expressed in pressure units of pound per square inch (psi) or bar. 5.3.1.4 Determine the hydrostatic yield pressure of pressure-sensitive components of the material by noting the point of divergence between the initial linear and secondary non-linear portions of the pressure-compression c
31、urve. The pressure at the point of divergence signifies the point at which pressure-sensitive compounds of the material begin to experience damage due to hydrostatic pressure. Since the pressure-compression chart is analogous to the stress-strain plots used for solid material compressive and tensile
32、 analysis, these well developed fields can provide many useful techniques for analysis. Depending upon the pressure response of the material being tested, the 0.2% offset method and the 25 to 75% method can be successfully used to determine hydrostatic yield pressure and effective compressive modulu
33、s. The analysis type used to determine these values should be reported. 5.3.1.5 Determine the amount of elastic compression of the material by subtracting the final displacement value from the largest material displacement value. Report this value as Rebound. Report the final measured density as Cru
34、sh. 5.3.1.6 Report the initial and final measured densities (by density cup) of the material, along with the calculated percent increase in density, as per the following formula: % Increase in Density = 100 x Where: p/final = density of material after compression testing p/initial = density of mater
35、ial before compression testing Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16695 Copyright 2012 General Motors Company All Rights Res
36、erved June 2012 Page 4 of 7 6 Safety This standard may involve hazardous materials, operations, and equipment. This standard does not propose to address all the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health p
37、ractices and determine the applicability of regulatory limitations prior to use. 7 Notes 7.1 Glossary. Not applicable. 7.2 Acronyms, Abbreviations, and Symbols. g/cc grams per cubic centimeter lb/gal pounds per gallon LVDT Linear Voltage Displacement Transducer psi pounds per square inch 8 Coding Sy
38、stem This standard shall be referenced in other documents, drawings, etc., as follows: Test to GMW16695 9 Release and Revisions This standard was originated in September 2011. It was first approved by Global Paint and Polymers in March 2012. It was first published in June 2012. Issue Publication Dat
39、e Description (Organization) 1 JUN 2012 Initial publication. Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16695 Copyright 2012 General
40、 Motors Company All Rights Reserved June 2012 Page 5 of 7 Appendix A Figure A1: Example of Pressure vs. Compression Curve Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WO
41、RLDWIDE ENGINEERING STANDARDS GMW16695 Copyright 2012 General Motors Company All Rights Reserved June 2012 Page 6 of 7 Figure A2: Schematic of Test Fixture Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted
42、without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW16695 Copyright 2012 General Motors Company All Rights Reserved June 2012 Page 7 of 7 Figure A3: Photo of Actual Test Equipment Setup to Run Test on Left Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
