Regarding the evaluation and analysis of the uncertainty of the non-metallic tension, pressure and multi-function testing machine load indication error inspection results, this paper mainly introduces the detection methods, detection steps, and precautions used in the evaluation process.
1 Overview
1.1 Measurement method
According to JJG157-1995 "Non-metal Tensile, Compression and Multifunctional Testing Machine Verification Regulations".
1.2 Environmental conditions
The temperature is (10～35)℃, and the temperature fluctuation is not more than 2℃/h.
1.3 Measuring standard
0. Grade 1 standard force measuring lever, the relative maximum allowable error is ±0.1%.
1.4 Measured object
For non-metal tensile, compressive and multifunctional testing machines (hereinafter referred to as testing machines), the maximum test force is not greater than 10MN, and the relative maximum allowable error is ±1.0%.
1.5 Measurement process
Under specified environmental conditions, use a standard force-measuring lever to apply a load to the testing machine to the measuring point. The load indication value of the testing machine corresponding to the standard force value can be obtained. This process is carried out three times continuously, and the arithmetic mean value of the three indication values is subtracted from the standard force value to obtain the indication error of the testing machine at the measuring point.
1.6 Use of assessment results
For testing machines that meet the above conditions and have a measurement range below 2.5 kN, the evaluation results of this uncertainty can generally be directly used, and other evaluation methods of this uncertainty can be used.
2 Mathematical model
ΔF=F-F
In the formula: Δ F—indication error of the testing machine;
F—the arithmetic mean value of the three indications of the testing machine;
F—Standard force value on the standard force gauge.
3 Evaluation of standard uncertainty of input quantity
3.1 Evaluation of the standard uncertainty u(F) of the input quantity F
The source of the standard uncertainty of the input quantity F is mainly the repeatability of the testing machine, which can be obtained by continuous measurement and evaluated by the method of type A.
For a 2.5kN testing machine, select 20% of the maximum measuring range as the measurement point, and measure 10 times continuously, and the measurement list is shown in Table 1.
4 Evaluation of composite standard uncertainty
