Tension/Compression (Direct Stress)Testing
Procedure and Results:
The specimen is mounted in an appropriate set of grips (optional) installed on the load cell and loading stud. The cyclic load and mean load are determined from known yield strength data. The mean load is applied with the load screw adjustment and locked in place. A trial stroke is chosen and the crank is adjusted to that value. (Manually operating the machine through one full cycle allows the loads to be verified.) Once the required loads are locked in, the machine is brought up to the desired speed and the counter is reset.
Completion of the test is determined by specimen fracture which actuates the cutoff switch, or the test may be stopped by means of the predetermined counter. Recording the digital readout of test cycles applied at the selected load completes the procedure for one data point.
Note that by removing the tension/compression attachment and installing other available test fixtures, other fatigue tests can be performed.
The DS-6000 test machine has a load capacity of up to 6000 lbs. and a variable stroke of up to 0.12″. The speed range is adjustable from 200 to 2000 cycles/minute. Model DS-6000-HLM (not shown) features a hydraulically operated actuator system which applies and maintains the test preload.