Astm d412 free download

NOTE t is advisable to provide a means for preventing the weights from falling to the floor in case the dumbbell should break. A stop watch or other suitable timing device which will register the time in minutes for at least 30 min shall be provided. A scale or other device. The sample shall be under no tension at the time it is marked. Marks shall be placed on the reduced section of the specimen equidistant from its center and perpendicular to its longitudinal axis.

The centers of the marks shall be either The median of the three measurements shall be used as the thickness in calculating the cross sectional area, except that specimens for which the differences between the maximum and minimum thickness exceeds 0. The specimens should not touch each other or the sides of the chamber except for momentary contact when agitated by the circulating air.

If a scale is used to measure the extension between bench marks, the scale shall be located parallel and close to the grip path during extension and shall be controlled from outside the cham ber. If obtained from a manufactured article the piece of rubber shall be freed of surface roughness, fabric layers, etc.

Specimens from units made in long lengths such as dredging sleeves, hose tubing, or insulation, shall be taken in the length direction, except that specimens of belts wider than mm 12 in. In the case of specially cured sheets prepared according to Methods D 15 the specimen shall be died out in the direction of the grain.

Dumbbell specimens shall conform in shape to those shown in Fig. In all cases, the cutting of test specimens shall be done with a single stroke of the cutting tool so as to assure obtaining smoothly cut surfaces.

In the case of heavy-walled tubing greater than 1. Ring specimens shall be of dimensions that permit the use of roller grips as described in 3.

From sheets 4 to 6 mm in thickness, the ISO standard ring specimen may be prepared with the following dimensions: Inside diameter From sheets prepared in accord-. The radial width shall be uniform within 0. The thickness of a standard ring specimen cut from a flat sheet may be assumed to be the thickness of the disk cut from inside the ring which can be measured with the micrometer Note 2.

Curved feet that fit the curvature of the ring shall be used in measuring the radial width. In measuring the axial thickness, the ball-tips of the micrometer shall be closed with the specimen resting on them. Then the tips shall be slowly separated until the specimen falls through of its own weight. If the area is determined from axial thickness and- 'radial width, three measurements shall be made at points distributed around the circumference of the ring, and the median of the three measurements shall be taken [or the thickness or width of the specimen.

The inside and outside diameters of ring specimens cut from a sheet may be assumed to be the same as that of the cutter determined from measurements of a ring of light cardboard cut by the cutter. The inside diameter of other ring specimens shall be measured by "the stepped cone described in 3. The inside circumference shall be obtained by multiplying the inside diameter by 3.

The size of these specimens gives the correct mean elongation within one percent when calculated in accordance with Note 9. These specimens shall be of sufficient length to permit their installation in the wedge or toggle grip used in the test. Bench marks shall be placed on the specimens as described for dumbbell specimens in 4. To determine the cross sectional area of straight specimens in the form of tubes, the weight, length, and density of the specimen shall be determined.

To determine the cross-sectional area' 'in square inches, the area A in square centimeters shall be multiplied by 0. Procedure 5. Specimens shall be conditioned for at least 3 h ifthe test temperature is 23 C.

If tension is greater on one side of the specimen than on the other, the bench marks will not remain parallel and maximum strength of the rubber will not be developed. Start the machine and note continuously the distance between the center of the two bench marks, taking care to avoid parallax. Record the stress at the elongation specified for the materials under test and at the time of rupture, preferably by means of an autographic or spark recorder.

At rupture measure and record the elongation to the nearest 10 percent on the scale. Place the specimen around the rollers with a minimum of tension. Start the machine and record or note continuously the distance between the centers of the rollers. NOTE 8-This equation is an approximation since changes in the cross sectional dimensions during extension have been neglected.

For precision measurements, substitute M - 3. At rupture measure the distance between the centers of rollers to within 2. The conditioning time at elevated temperatures must be limited to avoid additional curing or heat aging.

NOTE 9: Caution-Suitable heat-resistant gloves should be worn for hand and arm protection when testing at high temperature. An air mask is very desirable when the door of the chamber is opened to insert specimens; toxic fumes may be present and should not be inhaled by the operator conducting the test. Separate the grips at a rate of speed as uniformly as practicable, requiring about 15 s to reach the specified elongation.

Then hold the specimen at the specified elongation for 10 min, release quickly without being allowed to snap back, and allow to rest for an additional 10 min.

At the end of the IO-min rest period, measure the distance between the bench marks to the nearest 1 percent of original length. In stretching the specimen it has been found convenient to use a measured rod of a length equal to the exact distance required between the two bench marks.

Holding the rod behind the test specimen while it is being stretched simplifies the operation and reduces the chance of stretching the specimen more than the required amount. Use a stop watch or equivalent timer for recording the time required for the various operations.

Ten min after the specimen is broken, fit the two pieces carefully together so that they are in contact over the full area of the break. Measure the distance between the bench marks. The calculation is the same as. Calculate the tensile strength by letting F in the above equation for tensile stress be equal to the force required to break the specimen. Tensile stress and tensile strength are expressed in either kilograms-force per square centimeter' or pounds per square inch.

One kilogram-force per square centimeter is about NOTE The ultimate elongation of standard ring specimens cut from ASTM sheets may' be determined by mUltiplying the highest elongation indicated on the recorder chart by 1. This factor gives the elongation based on inside circumference,. Place the cutter in the drill press and adjust Diameter, inside Set the stop on the vertical travel of the spindle so that the tips Lubricate the sheet with Lower the cutter at a steady rate until it.

Be sure that the blade holder does not contact temperature. For below room temperature tests cool the speci- the sheet. If necessary, readjust the blade depth. Return the mens at the test temperature for at least 10 min prior to test.

Place another sheet. Rotate the mandrel and tubing in a Calculation lathe. Cut ring specimens to the desired axial length by means Lay eral calculated in the same manner as for dumbbell and straight thin wall tubing flat and cut ring specimens with a die or specimens with one important exception. Extending a ring cutting mechanism having two parallel blades. Do not outside dimension circumference , therefore for any extension use any stress in excess of that needed to overcome any of the grips, the inside strain or stress is greater than the ellipticity of the ring specimen.

The mean circumference is outside strain or stress because of the differences in the initial obtained by adding to the value for the inside circumference, unstrained dimensions.

The cut from the inside of the ring is measured with a micrometer rationale for this choice is that the mean circumference best described in Practice D For thin wall tubing, the area is calculated on the basis of the inside circumference since this represents from the axial length of the cut section and wall thickness. This location is the most probable site for the initiation of the Procedure rupture process that occurs at break.

Start the test machine and record the force and correspond- At rupture, measure and record the ultimate breaking elongation and the tensile force See Section 17 for calculations.

For tests at temperatures above 23C in. Use the inside diameter to program. The main program results are referred to as Test calculate the inside circumference for Type 2 rings. Report an appropriate value of r, R, r , or R , that is, that value to The appropriate value is that value of r or R 17, whichever is applicable, associated with a mean level in Tables closest to the mean Customary Units or Metric material in routine testing operations.

Units, was used. Two single test results, obtained under Two single test results obtained in two Precision and Bias different laboratories, under normal test method procedures, that differ by more than the tabulated R for any given level Refer to Practice D for sample populations.

For the r and R described below. Reference values do not exist for this test Both repeatability and repro- defined by the test method. Bias, therefore, cannot be deter- ducibility are short term, a period of a few days separates mined. A test result is the median value, as Both tion s or measurement s of the property or parameter in repeatability and reproducibility are short term, a period of a question. A test result is the A secondary interlaboratory test was conducted for one different days.

For this testing, uncured com- From ascending order of material average or level, for each of the these individually cured sheets, test specimens were cut and materials evaluated.

N 9. E R N N 1. R 2. E 9. Rhigh tensile NR. Emoderately filled EPDM. R 1. Reproducibility, R, varies over the range of the format of the following statements that use what is called material levels as evaluated.

MATL 5 MATL 6 MATL 1 MATL 4 MATL 2 MATL 3 The appropriate value is that value of r or R percentage of the mean level, r and R , have equivalent associated with a mean level in Tables closest to the mean application statements as For the level under consideration at any given time, for any given r and R statements, the difference in the two single test material in routine testing operations. Two single test results, obtained under ence between an average test value and the reference or true normal test method procedures, that differ by more than this test property value.

Reference values do not exist for this test tabulated r for any given level must be considered as derived method since the value of the test property is exclusively from different or nonidentical sample populations. Bias, therefore, cannot be deter- method has been established as the appropriate value tabulated mined.

Two single test results obtained in two different laboratories, under normal test method procedures, Keywords that differ by more than the tabulated R for any given level Users of this standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility.

This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years and if not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standards and should be addressed to ASTM International Headquarters.

Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend.

If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, at the address shown below. Individual reprints single or multiple copies of this standard may be obtained by contacting ASTM at the above address or at phone , fax , or service astm. Open navigation menu. Close suggestions Search Search. User Settings. Skip carousel. Carousel Previous. Carousel Next. What is Scribd? Uploaded by fuxyang. An extensometer is optional but recommended.

We recommend one for two reasons. First, dumbbell specimens do not have uniform widths which cause errors when both the wide and narrow sections of the dumbbell shaped specimen elongate at different rates. Secondly, elongation is usually an important design characteristic of rubbers and elastomers so an extensometer can be used to improve accuracy of the measurement.

Software or suitable electronics are required to operate the machine and to take the measurements. Basic systems will provide the raw data, and stress-strain charts. Using these sources of data, you can determine and calculate all of the analysis listed above. However, fully PC based systems have the capability to calculate all of these automatically. Elastomers pose a challenge to hold because they thin as they are stretchd. Therefore, the vast majority of elastomers need to be held with self tightening grips.

Examples of these grips are eccentric roller grips, wedge grips, or pneumatic grips. Regardless of the grip design, the concept is the same — they tighten on the material as it thins to keep constant force on the sample. Forgot your password? Previous Next.