Geometric Scaling and Modal Parameter Similarity Analysis of a Drill Pipe

Due to the restriction of thrust and space of the test bench,it is often difficult to carry out dynamic test on large drill pipes,so the combination of numerical simulation and scaled test piece test is a good solution to obtain the dynamic characteristics of drill pipes.In order to improve the dynamic performance parameter accuracy of the scaled drill pipe,a large drill pipe was taken as an example to study the modal parameters of the drill pipe,discuss the relationship between the finite element unit division scale and the convergence of the results,and determine the appropriate finite element unit division scale that meets the convergence requirements.The study results show that with comprehensive consideration to the calculation accuracy,computing efficiency and processability of scaled drill pipe,the optimal scaling ratio of the drill pipe is determined to be 25%.The comparison of modal frequency of 25% scaled drill pipe test and numerical simulation shows that the relative error is less than 3.8%.The conclusions provide theoretical and technical reference for the division of drill pipe numerical simulation units and the design of large drill pipe scaled test piece.