ASTM D695-02a pdf free.Standard Test Method for Compressive Properties of Rigid Plastics.
Measure the width and thickness of the specimen to thenearest 0.01 mm (0.001 in.) at several points along its length.Calculate and record the minimum value of the cross-sectionalarea.Measure the length of the specimen and record the value.10.2 Place the test specimen between the surfaces of thecompression tool, taking care to align the center line of its longaxis with the center line of the plunger and to ensure that theends of the specimen are parallel with the surface of thecompression tool. Adjust the crosshead of the testing machineuntil it just contacts the top of the compression tool plunger.NoTE 7—The compression tool may not be necessary for testing oflower modulus ( for example, 700 MPa to 3500 MPa ( 100 000 psi to 500000 psi)) material if the loading surfaces are maintained smooth,flat, andparallel to the extent that buckling is not incurred.
Place thin specimens in the jig (Fig. 3 and Fig.4) sothat they are flush with the base and centered (Note 8).The nutsor screws on the jig shall be finger tight (Note 9). Place theassembly in the compression tool as described in 5.3.
A round-robin test，designed to assess the influence ofspecimen positioning in the supporting jig (that is, flush versus centeredmounting), showed no significant effect on compressive strength due tothis variable. However, flush mounting of the specimen with the base ofthe jig is specified for convenience and ease of mounting. A round-robin test on the effect of lateral pressure at thesupporting jig has established that reproducible data can be obtained withthe tightness of the jig controlled as indicated.If only compressive strength or compressive yieldstrength,or both,are desired, proceed as follows:
Set the speed control at 1.3 mm/min (0.050 in./min)and start the machine.
Record the maximum load carried by the specimenduring the test (usually this will be the load at the moment ofrupture).
If stress-strain data are desired, proceed as follows:10.5.1 Attach compressometer.
Set the speed control at 1.3 mm/min (0.050 in./min)and start the machine.Record loads and corresponding compressive strainat appropriate intervals of strainor,if the test machine isequipped with an automatic recording device,record thecomplete load-deformation curve.After the yield point has been reached, it may bedesirable to increase the speed from 5 to 6 mm/min (0.20 to0.25 in/min) and allow the machine to run at this speed untilthe specimen breaks. This may be done only with relativelyductile materials and on a machine with a weighing systemwith response rapid enough to produce accurate results.ASTM D695 pdf download.