The propagation of manufacture uncertainty to dynamic measurement

Abstract

Uncertainty is the degree of suspicious for correctness or accuracy of measurement results. Parts of the manufacturing error directly affect the structural dynamic characteristics. The propagation of uncertainty in the static measurement from characteristics to the measurement results has been investigated for decades. However, the propagation of manufacture uncertainty to the results of dynamic measurement has been rarely investigated, which is an important issue for the design and tests of structures and equipment. In this paper, the propagation of manufacturing uncertainty to the dynamic measurement is investigated on the basis of modal analysis method. The manufacturing uncertainty here is represented by the tolerance of form and position, which is the difference between actual shape or position and the digital 3D model of geometry shape and position. Tolerance of form and position is an< important indicator to evaluate object geometry size and the relative position in the mechanical design. The uncertainty of the tolerance of form and position is assumed to satisfy Gaussian distribution. The relationship between modal parameters and tolerance is predicted by analyzing transition rules of modal parameters. A series of beams with tolerance of form and position analyzed experiment to verify transitive relation between varied modal parameters in modal analysis and tolerance. The investigation found that the distribution of the uncertainty of the parameters of dynamic measurement, such as the natural frequencies and modal shapes, are not inherently satisfied with Gaussian distribution, although the uncertainty of characteristics are Gaussian distributed, which confirms the difference of uncertainty propagation in the static measurement and dynamic measurement.