高精度声学法体积测量技术基础研究

The volume of a weight needs to be precisely measured for buoyancy correction of the weight mass in air. Acoustic method is a non-contact way with high measuring efficiency for the determination of solid volume. To improving the measuring accuracy of the weight volume, decrease the non-linearty error caused by the shape and size of weights when using the acoustic method, an innovative aoustic method with two measuing cavity are poposed in this research. Simulation method is used to determine the influece model of the shape, surface area of weights and two measuing cavities to the acoustic method. And the experiments of measuring the volume of weights with special shapes ranging from 5 kg to 100 g will be carried out to evaluate the performance of the innovative acoustic method with two measuring cavities. The relative uncertainty below 8×10?4 is expected to be achieved..This project combines the advantages of innovative measurement methods, numerical measuring theory study and the prototype development. The project is expected to provide theoretical models and technique optimization to improve the precision and reliability of volume measurement using acoustic method. This project can provide key technical solutions for the high efficiency and practical volume measurement of the high-grade weights in mass metrology.

声学法是一种快速高效的非接触式体积测量方法。为解决声学法体积测量因标准砝码与被测砝码因形状、表面积等不同引起的测量非线性误差的修正问题，本课题将提出一种创新的双腔体测量方法，并采用数值模拟手段，研究确定砝码形状系数、表面积、测量腔体大小、形状等对声学法体积测量过程的影响，提高声学法体积测量的测量精度、稳定性。在这些基础研究的基础上，自主设计进行声学法砝码体积测量系统的优化和完善，并进行系统的实验及性能测试研究，期望对于标称质量为5 kg~100 g的异形砝码的测量相对不确定度进一步降低，优于8×10-4 (k=2)。.本课题将创新测量方法、基础数值机理理论研究与样机优化研制有机结合，为提高声学法砝码体积测量的高精度与高可靠性提供模型基础、理论方法和技术手段，课题研究成果可为发展我国高等级砝码的高效率、实用化体积测量方法解决关键技术问题。

本项目研究应用于质量计量领域。声学法是一种快速高效的非接触式体积测量方法。针对固体材料的体积，特别是质量标准-砝码的体积测量，为解决声学法体积测量中因参考砝码与被测砝码因形状、表面积等不同引起的测量非线性误差的修正问题，本项目提出并实现了一种双腔体非线性误差自相关的声学法体积测量方法，获得国家发明专利授权。 .本项目首次设计并实现了一套双腔体非线性误差自相关的声学法体积测量装置；完成了新测量方法的理论计算公式推导；采用数值仿真分析手段，研究分析了测量腔体大小等对声学法体积测量过程的影响；完成了声学法砝码体积测量系统的设计和优化。并使用表面积与体积比不同的参考砝码和被测发码，对标称质量为5 kg~100 g的被测砝码进行了系统性能测试研究，测量相对不确定度优于8×10-4 (k=2)。并为进一步研究提出一种五步双腔体测量序列，可计算并检测腔体及砝码表面非线性体积层的稳定性。