Downloaded from https://www.everyspec.com MIL-sTD-1312B a. Connect the associated instrumentation, such as the adjustable bridge circuit power supply, amplifier, and oscilloscope, etc., to the dynamometer transducer and, after switching on, allow the requisite period for stabilization. b. Minimize bending by mounting the dynamometer in such a way that the strain measured by any one of the measuring elements of the transducer attached to the dynamometer does not differ by more than 6 percent from the average of the strain measured by all the elements at any load in the dynamometer range. Measure output for zero load with only one end of the dynamometer gripped in the testing machine. 1 I c.
least three times from zero load to the maximum load of the dynamometer range. The change in axial strain recorded after a period of not less than 1 minute at the minimum load, on consecutive readinga, shall not exceed Prior to static calibration, apply and remove loads at ( I *O.2 percent of the axial strain at the maximum load. , d. Apply static loada in not leaa than five approximately equal increments up to the maximum of the dynamometer range. At each increment, simultaneously record the transducer strain readings and load. t ,. e. Unload the dynamometer in not less than five approximately equal increments to zero load.
At each increment, simultaneously record the transducer strain readings and load. f. Repeat operations c, d and e twice to obtain three series of calibration readings. Between each two series of readinga, rotate the dynamometer approximately 30 degrees to facilitate the detection of maximum bending. Between the second and third series of readinga disconnect the aaaociated transducer instrumentation and remove the dynamometer from the testing machine, and then remount it as above. The average strain meaaured during any one series shall not differ by more than 1 percent from the average strain of all three series. g.
mean of the three series of transducer and indicated Obtain the static calibration of the dynamometer from the l o a d s of the static or fatigue testing machine or dead weights. The relationship between load and strain should be essentially linear. 70. PROCEDURE FOR STATIC ALIGNMENT 70.1 Equipment. Equipment described in Section 6 may be used for static alignment and dynamic loaF verification, aa applicable. I 113