A method for establishing a bearing residual life prediction model for process enhancement equipment based on rotor imbalance response analysis

A rotating packed bed is a typical chemical process enhancement equipment that can strengthen micromixing and mass transfer.During the operation of the rotating packed bed,the nonreactants and products irregularly adhere to the wire mesh packing in the rotor,thus resulting in an imbalance in the vibration of the rotor,which may cause serious damage to the bearing and material leakage.This study proposes a model prediction for estimating the bearing residual life of a rotating packed bed based on rotor imbalance response analysis.This method is used to determine the influence of the mass on the imbalance in the vibration of the rotor on bearing damage.The major influence on rotor vibration was found to be exerted by the imbalanced mass and its distribution radius,as revealed by the results of orthogonal experiments.Through implementing finite element analysis,the imbalance response curve for the rotating packed bed rotor was obtained,and a correlation among rotor imbalance mass,distribution radius of imbalance mass,and bearing residue life was established via data fitting.The predicted value of the bearing life can be used as the reference basis for an early safety warning of a rotating packed bed to effectively avoid accidents.

Modeling and Dynamic Analysis for the Foundation of a Blade-Rotor System

In order to achieve the model-based fault monitoring and diagnosis,an accurate model for the rotor system is necessary to locate and quantify faults.Since the dynamic characteristics of a blade-rotor system is influenced by foundation flexibility,the modeling and dynamic analyses on the foundation were sequentially investigated.Firstly,the effect of element size on the model convergence was investigated using the forward difference quotient as the slope of the frequency difference,which found that the model converged when the element size refined to 4mm.Secondly,a modal analysis and a harmonic response analysis were performed to obtain the dynamic characteristics of the foundation structure.Finally,an optimization to the foundation utilizing an additional stiffener was conducted to reduce the foundation response and make the critical speed far away from the working frequency band of 20—50Hz.

Design and Performance Study of an Ultrasonic Bone Scalpel with Composite Horn Structure

The ultrasonic bone scalpel was often used in all kinds of clinical orthopedic surgery as a new type of medical instrument.Based on the working theory of the ultrasonic bone scalpel and combined with the design method of a quarter wavelength transducer and horn,this study proposed an optimization design method for the ultrasonic bone scalpel with a composite horn structure.The structure of the ultrasonic bone scalpel was simplified,and its length was shortened.Finite element analysis,modal analysis,and harmonic response analysis were used to optimize the design of the ultrasonic bone scalpel.The performance of the ultrasonic bone scalpel was explored through impedance analysis,amplitude measurement,temperature measurement,and cutting tests,and the feasibility of the design was verified through torque analysis.The results showed that when the torque force was 4.0 N,the resonance frequency of the ultrasonic bone scalpel was 30,540 Hz,and the maximum amplitude of the ultrasonic bone scalpel could reach 62μm.After spray cooling,the maximum surface temperature of the rear end cover was reduced from 51.8 to 36.3℃,the maximum surface temperature of the composite horn was reduced from 71 to 45.3℃,and the maximum surface temperature of the cutter head was reduced from 101 to 46.1℃,demonstrating a good cooling effect.Under 89 Voltage,the optimal cutting force for cutting chicken leg bones was 0.1 N,the optimal cutting force for cutting pork ribs was 0.3 N,and the cutting process showed tissue selectivity.