Research On The Uncertainty Of The Standard Value Of The Moment Of Inertia Standard Parts

The moment of inertia is an important parameter in flyer's dynamics research,adjustment of flying attitude and flying control,it's important to measure the moment of inertia accurately for ensuring the security control of flyer.The measurement of moment of inertia is founded on the to-and-fro circular motion,we need standard specimen to calibrate the system's stiffness,so as the standard of the whole system,standard specimen's uncertainty have great impact in the whole system's uncertainty.In this paper,we do a preliminary study on standard specimen,the valuation of standard specimen is got by theoretical calculation,the affecting factor of standard specimen's valuation usually include the uncertainty of physical dimension,the uncertainty of mass,the uncertainty of density's homogeneity.For those factors,we mainly do a study on the uncertainty of density's homogeneity and prove that the uncertainty of standard specimen made in rolling and forging can meet the requirement of engineering.The main works is as follows:(1)Based on the principle of uncertainty's transmitting,we establish the model of uncertainty's transmitting by the theoretical formula of moment of inertia and analyze factors' uncertainty simply,make preparation for study on density homogeneity.(2)Explanation to the homogeneity of material is made,then prove the material's density can meet the requirement of macroscopic homogeneity by plastic deformation.(3)Based on the requirement of engineering practice,we restructure the particle and hole and establish the model to research the moment of inertia's deviation with numerical analysis caused by density homogeneity.(4)By SEM observation and dynamic balance statics,the assumption of porosity is proved to be reasonable and macroscopic homogeneity is set up.The cross check of standard specimens equipped with measuring equipment of moment of inertia show that theoretical value match with measured value,the result proved that theoretical value is accurate.