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Upper Crosshead and Lower Crosshead. The upper crosshead is used to clamp one end of the test specimen. The lower crosshead in the load frame is the movable crosshead whose screws can be loosened for height adjustment and tightened. Both the crossheads have a tapered slot at the center.
Components of Universal Testing Machine. Two primary components make up a universal testing machine as follow: Loading Unit. Control Unit. Loading Unit. The loading unit controls how the test specimen is set up and how much force is applied. The table and crosshead on the left unit make up the loading unit.
crosshead testing speed of 2 in/min or 0.033 in/sec. With a servo update rate of 1,000 times per. second, the desired crosshead movement per servo update = 0.033/1000 = 0.000033 inches/servo. update. Example 2: Apply a 10 lbf peak to peak sinewave force amplitude at 5 Hz (cycles per second) to a test. sample.
MOVING CROSSHEAD (4) The moving crosshead is essentially a crosshead that is controlled to move up or down. In a tensile test, the crosshead speed of the testing machine is directly related to the strain rate in a specimen. ELECTRONICS (5) The electronics control the moving parts of the tensile testing machine.
Internationally recognized standards have been developed for calibration of crosshead speed and displacement (ASTM E2658 and E2309), strain and load rate (ASTM E2309), and measurement of tension, compression (ASTM E4), torque (ASTM E2624), and dynamic force (ASTM E467).
Generally, one set of crosshead position PID control gains on a static testing machine will generate acceptable crosshead position control over almost the complete speed range of the machine. A second set of crosshead position PID control gains with larger proportional gain (Kp) and integral control gain (Ki) values may be needed for extremely ...
Cross head - A movable cross head (crosshead) is controlled to move up or down. Usually this is at a constant speed: sometimes called a constant rate of extension (CRE) machine.
