Bartel Thomas W, Yaniv Simone L
National Institute of Standards and Technology, Gaithersburg, MD 20899-0001.
J Res Natl Inst Stand Technol. 1997 May-Jun;102(3):349-362. doi: 10.6028/jres.102.024.
The 60 min creep data from National Type Evaluation Procedure (NTEP) tests performed at the National Institute of Standards and Technology (NIST) on 65 load cells have been analyzed in order to compare their creep and creep recovery responses, and to compare the 60 min creep with creep over shorter time periods. To facilitate this comparison the data were fitted to a multiple-term exponential equation, which adequately describes the creep and creep recovery responses of load cells. The use of such a curve fit reduces the effect of the random error in the indicator readings on the calculated values of the load cell creep. Examination of the fitted curves show that the creep recovery responses, after inversion by a change in sign, are generally similar in shape to the creep response, but smaller in magnitude. The average ratio of the absolute value of the maximum creep recovery to the maximum creep is 0.86; however, no reliable correlation between creep and creep recovery can be drawn from the data. The fitted curves were also used to compare the 60 min creep of the NTEP analysis with the 30 min creep and other parameters calculated according to the Organization Internationale de Métrologie Légale (OIML) R 60 analysis. The average ratio of the 30 min creep value to the 60 min value is 0.84. The OIML class C creep tolerance is less than 0.5 of the NTEP tolerance for classes III and III L.
美国国家标准与技术研究院（NIST）依据国家型式评价程序（NTEP）对65个称重传感器进行了60分钟蠕变测试，对测试数据进行分析，以比较它们的蠕变和蠕变恢复响应，并将60分钟蠕变与更短时间段内的蠕变进行比较。为便于比较，将数据拟合成一个多项指数方程，该方程能充分描述称重传感器的蠕变和蠕变恢复响应。使用这种曲线拟合可减少指示器读数中的随机误差对称重传感器蠕变计算值的影响。对拟合曲线的检查表明，蠕变恢复响应在符号改变后反转，其形状通常与蠕变响应相似，但幅度较小。最大蠕变恢复绝对值与最大蠕变的平均比值为0.86；然而，从这些数据中无法得出蠕变与蠕变恢复之间可靠的相关性。拟合曲线还用于比较NTEP分析中的60分钟蠕变与根据国际法制计量组织（OIML）R 60分析计算的30分钟蠕变及其他参数。30分钟蠕变值与60分钟蠕变值的平均比值为0.84。对于III类和III L类，OIML C级蠕变公差小于NTEP公差的0.5。
