scholarly journals Dynamic modeling and analysis of the nut-direct drive system

2018 ◽  
Vol 10 (11) ◽  
pp. 168781401881065
Author(s):  
Zhaoguo Wang ◽  
Xianying Feng ◽  
Peigang Li ◽  
Fuxin Du
Keyword(s):  
Dynamic Models ◽  
Drive System ◽  
Parameter Method ◽  
Position Tracking ◽  
Servo Motor ◽  
Direct Drive ◽  
Tracking Accuracy ◽  
Feed System ◽  
Lumped Parameter ◽  
Lumped Parameter Method

For ball screw feed system, it has been a common practice that screw shaft is typically supported by bearings at both ends and is driven by a servo motor through coupling. However, this drive method has a relative low dynamic rigidity due to the influence of the support bearings. In this study, the nut-direct drive system is proposed, where the screw shaft is fixed at both ends and the screw nut is driven by the hollow servo motor through the bolted flange. In order to analyze the advantages of the nut-direct drive system compared with the classical drive, the dynamic models of the classical drive and the nut-direct drive are established based on lumped parameter method, respectively. According to the lumped parameter method, the influence of the table position, the length of screw shaft, and the nominal diameter of screw shaft on the natural frequency are analyzed. Furthermore, to analyze the influence of the mechanical system on position tracking accuracy, the mechanical systems of the classical drive and the nut-direct drive are integrated into the control system using the same control parameters, respectively. Results indicate that the nut-direct drive has faster responsiveness and better position tracking accuracy compared with the classical drive.

An improved lumped parameter method for calculating static characteristics of multi-recess hydrostatic journal bearings

2019 ◽  
Vol 234 (2) ◽  
pp. 301-310
Author(s):  
Yongtao Zhang ◽  
Shijie Yu ◽  
Changhou Lu ◽  
Haixia Zhao ◽  
Peng Liang
Keyword(s):  
Total Pressure ◽  
Control Volume ◽  
Journal Bearings ◽  
Parameter Method ◽  
Static Characteristics ◽  
Application Range ◽  
Continuity Equations ◽  
Pressure Distributions ◽  
Lumped Parameter ◽  
Lumped Parameter Method

This paper proposes an improved lumped parameter method for calculating the static characteristics of multi-recess hydrostatic journal bearings. The improved lumped parameter method can estimate the total pressure distribution in the circumferential direction by introducing control volume in the middle of each inter-recess land, and utilizing the flow continuity equations for each recess and each control volume with the assumption that the pressure distributions are parabolic on the inter-recess land. Then the recess pressure and the fluid film force can be calculated. The calculation accuracy of the improved lumped parameter method and the traditional lumped parameter method is comparatively discussed under different eccentricity ratios and wrap angles of the recess. The results show that the improved lumped parameter method has higher calculation accuracy and wider application range.

scholarly journals Analysis and Application of Screens for Acoustic Impedance in a Speaker Box with a Passive Radiator to Decrease Standing-Wave Influence

2020 ◽  
Vol 10 (3) ◽  
pp. 866
Author(s):  
Yuan-Wu Jiang ◽  
Dan-Ping Xu ◽  
Zhi-Xiong Jiang ◽  
Jun-Hyung Kim ◽  
Ki-Hong Park ◽  
...  
Keyword(s):  
Standing Wave ◽  
Acoustic Resonance ◽  
Experimental Result ◽  
Parameter Method ◽  
Analysis Tool ◽  
Analysis Method ◽  
The Finite Element Method ◽  
Lumped Parameter ◽  
Acoustic Domain ◽  
Lumped Parameter Method

Micro speakers are playing an increasingly important role with the development of multimedia devices. This study applies the lumped-parameter method, which uses an equivalent circuit to model the electromagnetic and mechanical domains. The acoustic domain is modeled using the finite element method. Based on the analysis tool, the use of a screen is analyzed, and the screen is designed to depress the acoustic resonance in the sound-pressure-level curve and improve the performance. The samples are fabricated, and the experiment verifies the analysis method. The experimental result shows that the peak and dip due to the standing wave are cancelled, and the frequency response is smooth when the screen is used.

A Simple Shear and Torsion-Free Beam Model for Multibody Dynamics

2017 ◽  
Vol 12 (5) ◽  
Author(s):  
Juan Carlos García Orden ◽  
Javier Cuenca Queipo
Keyword(s):  
Computer Animation ◽  
Axial Stiffness ◽  
Parameter Method ◽  
Beam Model ◽  
Nonlinear Dynamical ◽  
Lumped Parameter ◽  
Proposed Model ◽  
Space Mechanisms ◽  
Lumped Parameter Method ◽  
Free Beam

This paper describes a very simple beam model, amenable to be used in multibody applications, for cases where the effects of torsion and shear are negligible. This is the case of slender rods connecting different parts of many space mechanisms, models useful in polymer physics, computer animation, etc. The proposed new model follows a lumped parameter method that leads to a rotation-free formulation. Axial stiffness is represented by a standard nonlinear truss model, while bending is modeled with a force potential. Several numerical experiments are carried out in order to assess accuracy, which is usually the main drawback of this type of approach. Results reveal a remarkable accuracy in nonlinear dynamical problems, suggesting that the proposed model is a valid alternative to more sophisticated approaches.

scholarly journals Analysis and Design of Helmholtz Protector to Improve High-Frequency Response of Insert Earphone

2019 ◽  
Vol 9 (12) ◽  
pp. 2541 ◽  
Author(s):  
Yuan-Wu Jiang ◽  
Dan-Ping Xu ◽  
Zhi-Xiong Jiang ◽  
Jun-Hyung Kim ◽  
Sang-Moon Hwang
Keyword(s):  
Frequency Response ◽  
High Frequency ◽  
Experimental Result ◽  
Parameter Method ◽  
Analysis Tool ◽  
Analysis Method ◽  
Analysis And Design ◽  
High Frequency Response ◽  
Lumped Parameter ◽  
Lumped Parameter Method

With the development of multimedia devices, earphones are playing an increasingly important role. This article applies the lumped parameter method using an equivalent circuit to model the electromagnetic, mechanical, and acoustic domains of earphones. Then, parameters are determined according to the dimensions and material properties of earphone parts. On the basis of the analysis tool and determined parameters, a Helmholtz protector is analyzed and designed to improve the high-frequency response. Samples are fabricated, and the experiment verifies the analysis method. The experimental result shows that the peaks at 7 k and 10 k are decreased at 8.05 dB and 7.89 dB. The root means square value of SPL deviation compared with target curve decreased from 9.77 to 4.39. High-frequency response is improved by using the Helmholtz protector.

The Bending Vibration Analysis on the Main Drive Axis of CNC Spiral Bevel Gear Milling Machine

2013 ◽  
Vol 655-657 ◽  
pp. 1296-1299
Author(s):  
Li Juan Yu ◽  
Zhao Jun Yang ◽  
Fu You Liu
Keyword(s):  
Drive Shaft ◽  
Resonance Problem ◽  
Parameter Method ◽  
Force Model ◽  
Lumped Mass ◽  
Mass Model ◽  
Bending Vibration ◽  
Lumped Parameter ◽  
Lumped Mass Model ◽  
Lumped Parameter Method

Gear machine tool main drive shaft to avoid resonance problem is studied.The force of the drive shaft is analyzed, and the vibration form of the drive shaft is confirmed. Using the lumped parameter method to simplify the main drive shaft, the lumped mass model and the force model were been obtained. When bending vibrating, the natural frequency of the main drive shaft is calculated using the transfer matrix method. The calculated critical speed is 43755r/min, which far outweighs the motor rated speed .It means that the drive shaft under normal work won't be resonance, which accords with the request of production.

Dynamic Analysis of the Crank Train in a Single Cylinder Diesel Engine Using a Lumped Parameter Method

2016 ◽  
Author(s):  
X. Y. Zhang ◽  
J. Guo ◽  
Zhang Wenping
Keyword(s):  
Diesel Engine ◽  
Dynamic Analysis ◽  
Internal Force ◽  
Parameter Method ◽  
Cylinder Pressure ◽  
Connecting Rod ◽  
Single Cylinder ◽  
Rotating Speed ◽  
Lumped Parameter ◽  
Lumped Parameter Method

The kinematic and dynamic behaviors of the crank train in a single cylinder diesel engine are analyzed in the paper. The crank train mechanism consists of four parts: a crank without counterweight, a connecting rod, a piston associated with a cylinder and two stops at both ends of a stroke. The dynamic model is developed using a lumped parameter method. The inertia of mass or moment are considered by an equivalent treatment in the centers of the piston pin, the crank pin, the main journal, respectively. The longitudinal deformations of the connecting rod are simulated by spring-damping elements, as well as the angular and bending deformations of the crank. As a result, it was possible to predict the effects of the component inertia of mass or moment and stiffness on the internal force and rotating speed of the crank under the cylinder pressure.

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