Dynamic simulation of a flexible spinning vehicle with the periodic varying thrust

Abstract

The dynamic response of a flexible spinning vehicle with the varying thrust was investigated. The varying thrust was modeled as a series of simple harmonic components superimposed on a constant thrust. The analytical solutions for longitudinal motion were obtained by combining the motion equations and boundary conditions, and then, the transverse bending of rocket was examined solved by considering a coupled forcing vibration with varying parameters. Numerical solutions for a rocket with end-varying thrust were studied. It is shown that the lateral vibrations and motion attitudes of rocket depend on the frequencies of varying thrust to great extent, and an important phenomenon, beating, maybe take place. The proposed approach is more accurate and efficient in comparison to those standard numerical techniques.

Comparative study of soft drafting system and the conventional drafting system based on the ring spinning frame

“…In the spinning process, pressure distribution in the drafting zone and motion states of the drafting parts are the key factors affecting fiber motion, thereby affecting yarn quality. 1 For the conventional drafting system (CDS), pressure on fibers mainly comes from rollers and double aprons, and the experimental methods for measuring pressure between top and bottom aprons include two methods: static measurement 2 and dynamic measurement. 3 Fujino et al.…”

“…4 used dynamic measurement with an electric measuring apparatus to measure and calculate the pressure distribution during the operation of the spinning frame, the result of which was lower and smoother than the actual distribution. Shu 2 and Quan and colleagues 5,6 carried out three-dimensional (3D) modeling of the double-apron drafting system and a novel drafting system based on the spinning frame, and used the finite element method to simulate pressure distributions. Gui and Gui 7 and Wang and Wang, 8 with the help of a computer, used the Hertzian contact theory to calculate the pressure of top rollers with different hardness on slivers, with the conclusion that soft rollers are more reasonable in controlling fibers.…”