Study on dry friction vibration model based on energy method

Purpose This study aims to establish the friction vibration model. Design/methodology/approach The friction vibration experiment was carried out on a pin disk friction tester. The causes of friction vibration are discussed, and the friction vibration model is established based on the energy method. Findings The experimental and simulation results show that the main cause of friction vibration is the nonlinear change of friction coefficient; degree of the friction vibration has a positive relationship with the friction relative velocity and normal contact positive pressure; the proposed friction vibration model is highly consistent in chaotic attractor and time-frequency distribution map and can well predict friction vibration. Originality/value The proposed friction vibration model is highly consistent in chaotic attractor and time-frequency distribution map and can well predict friction vibration.

Propagation Characteristics of Pressure Pulsation in Hydraulic Hose

Most modern aircraft hydraulic systems use variable plunger pumps. The pulsating flow output is its inherent characteristic. The resulting pressure pulsation often causes serious damage to the energy pipeline system and endangers the lives of the occupants. This paper studies the propagation law of hydraulic oil in hydraulic hoses, fully considers the coupling vibration of hydraulic oil high-pressure fluid and flexible solids of the hose, establishes a fluid-solid coupling vibration model of hydraulic hoses, and uses ANSYS for numerical simulation to study different frequencies and pipe bending. Using ANSYS for numerical simulation to study the influence of different frequencies and pipe bending radii on the amplitude of fluid pressure pulsation, after comparative analysis, the law of fluid pressure pulsation propagation in hydraulic hoses is obtained.

Vibration response of defect-ball-defect of rolling bearing with compound defects on both inner and outer races

Aiming at the problem that the existing compound defects model of rolling bearings under radial load is difficult to reflect the actual contact between rolling elements and defects. A new model is proposed to accurately reflect the simultaneous or sequential contact between inner and outer race defects and rolling elements. Considering the coupled excitation between shaft and bearing and pedestal, time-varying displacement excitation, and radial clearance, a four degree-of-freedom vibration model of rolling bearing with compound faults on both inner and outer races is built. The vibration equations are calculated by the method of numerical way, and the model is verified by experiment. The vibration response characteristics of the Defect-Ball-Defect model are studied, which renders a theoretical criterion for bearing fault diagnosis.

Analytical and Numerical Investigations of Mechanical Vibration in the Vertical Direction of a Human Body in a Driving Vehicle using Biomechanical Vibration Model

The main reason that affects the discomfort in a driving vehicle is the vibration response. The human body vibration leads to many malfunctions in both comfort and performance in human health. As a result, the human body’s simulation in sitting posture in the driving vehicle has a strategic relationship for all Tires and vehicles manufacturers. The digital process simulation of the human body seat vehicle vibration shows two significant advantages. The first advantage is the prevention of the high-cost modifications in the construction stage of the vehicle, while the second one describes the stability test during the undesirable vibrations. This study modelled the human body’s dynamic characterisations, natural frequency, and mechanical response when seated in the driving vehicle with vibration transmissibility in the vertical direction have been using the biomechanical vibration model. The vertical vibrations and the transmissibility of the human body dynamic response are presented in detail. Exciting results have been obtained, and they are significant for human health, which relates to sitting posture in the driving vehicle. It can assist in understanding the influences of low-frequency vibration on human health, comfort, and performance, and therefore it could be applied for ride comfort evaluation. An analytical solution to derive the general equations of motion for the human system was developed. Then, using the vibration analysis technique and the corresponding equations, the accurate dynamic response of the selected mode is identified. Furthermore, the mathematical modelling for free vibration using the finite element analysis has been performed to determine the appropriate values and set its description. Then, the comparison results of the two techniques have been carried out.