scholarly journals Mathematical modeling and parametric identification of dynamic properties of mechanical subsystems tool and workpiece in turning process

2018 ◽  
Vol 226 ◽  
pp. 02017
Author(s):  
Pham Dinh Tung
Keyword(s):  
Mathematical Modeling ◽  
Dynamic Properties ◽  
Parametric Identification ◽  
The Self ◽  
Cutting Process ◽  
Machining Accuracy ◽  
Turning Process ◽  
Stiffness Properties ◽  
Dynamic Structures ◽  
The Stability

Research and modeling of dynamic structures of the subsystems tool and the workpiece is given continued attention. This is due to the fact that the analysis of the stability of the cutting process and the self-oscillation is necessary, first of all, to have a model of the dynamics of interacting subsystems tool and workpiece through the cutting process. A similar problem is in the study of the machining accuracy, particularly in cases where the workpiece has significant deformation displacement varying along the trajectory of the tool relative to the workpiece. This paper considers the problem of mathematical modeling and identification of inertial, damping, and stiffness properties of the subsystems tool and workpiece in the dynamics exercises of the cutting process. The algorithms and the results of the identification of parameters in mathematical models of mechanical subsystems tool and workpiece for the case of turning are resulted.

Experimental Study of the Dynamic Behavior of Thin-Walled Tubular Workpieces in Turning Cutting Process

2020 ◽  
pp. 1-19
Author(s):  
Zied Sahraoui ◽  
Kamel Mehdi ◽  
Moez Ben Jaber
Keyword(s):  
Dynamic Behavior ◽  
Cutting Forces ◽  
Chip Thickness ◽  
Cutting Process ◽  
Machining Process ◽  
Structural Damping ◽  
Turning Process ◽  
Manufactured Products ◽  
Thin Walled ◽  
The Stability

Nowadays, industrialists, especially those in the automobile and aeronautical transport fields, seek to lighten the weight of different product components by developing new materials lighter than those usually used or by replacing some massive parts with thin-walled hollow parts. This lightening operation is carried out in order to reduce the energy consumption of the manufactured products while guaranteeing optimal mechanical properties of the components and increasing quality and productivity. To achieve these objectives, some research centers have focused their work on the development and characterization of new light materials and some other centers have focused their work on the analysis and understanding of the encountered problems during the machining operation of thin-walled parts. Indeed, various studies have shown that the machining process of thin-walled parts differs from that of rigid parts. This difference comes from the dynamic behavior of the thin-walled parts which is different from that of the massive parts. Therefore, the purpose of this paper is to first highlight some of these problems through the measurement and analysis of the cutting forces and vibrations of tubular parts with different thicknesses in AU4G1T351 aluminum alloy during the turning process. The experimental results highlight that the dynamic behavior of turning process is governed by large radial deformations of the thin-walled workpieces and the influence of this behavior on the variations of the chip thickness and cutting forces is assumed to be preponderant. The second objective is to provide manufacturers with a practical solution to the encountered vibration problems by improving the structural damping of thin-walled parts by additional damping. It is found that the additional structural damping increases the stability of the cutting process and reduces considerably the vibrations amplitudes.

scholarly journals The change of the properties of the turning process by introducing vibrations in the cutting zone

2018 ◽  
Vol 226 ◽  
pp. 02010
Author(s):  
Vilor Zakovorotny ◽  
Valery Gvindjiliya
Keyword(s):  
Mathematical Modeling ◽  
Nonlinear Interaction ◽  
Vibration Amplitude ◽  
Cutting Process ◽  
Output Process ◽  
Turning Process ◽  
Process Characteristics ◽  
Cutting Zone ◽  
Cutting System

The results of the research of the vibrations influence are raising in the cutting zone on the output properties of the cutting process are represented. The results of the mathematical modeling of the dynamic cutting system are represented in which the controlling oscillatory displacements are raised. The system is considered as the unity subsystem of the tool and the detail are interacting through the processing. It is shows that the additional vibrations transform in the geometry topology of the forming surface as the result of the complex nonlinear interaction of the oscillations and the forces. The additional oscillations can cause as improvement of accuracy, quality and intensity of the tool wearing as deterioration of output process characteristics depending on the parameters of the vibration (amplitude, frequency and orientation). The results of the research of the oscillations influence on the quality of the surface and the power of the irreversible transformations which characterize the cutting process state are represented.

Dynamic Behavior of a Thin-Walled Cylindrical Workpiece During the Turning-Cutting Process, Part 2: Experimental Approach and Validation

2002 ◽  
Vol 124 (3) ◽  
pp. 569-580 ◽  
Author(s):  
K. Mehdi ◽  
J.-F. Rigal ◽  
D. Play
Keyword(s):  
Dynamic Behavior ◽  
Experimental Approach ◽  
Element Model ◽  
Central Place ◽  
Operating Conditions ◽  
Cutting Process ◽  
Turning Process ◽  
Cylindrical Workpiece ◽  
Thin Walled ◽  
The Stability

Chatter vibrations in the cutting process have a central place in many machining applications. A numerical and theoretical approach of self-excited vibrations during the turning process of thin-walled hollow workpieces has been presented in the accompanying paper. Furthermore, a finite element model has been proposed to simulate the dynamics of the system. The response to a Dirac excitation, presented as Nyquist curves, is proposed in order to characterize the dynamics of the turning process and the stability criterion. In this the second part of two related papers, the main objective is to validate the simulated dynamic behavior by using the experimental approach. The results of machining tests performed on thin-walled tubes with steel and aluminum alloys, using different operating conditions (dimensions, geometry and setting conditions) are presented and discussed.

Application of the method of mathematical modeling for forecasting channel deformations at the underwater crossing of the main pipeline

2020 ◽  
Vol 10 (6) ◽  
pp. 599-609
Author(s):  
Valery А. Gruzdev ◽  
◽  
Georgy V. Mosolov ◽  
Ekaterina A. Sabayda ◽  
◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Roughness Coefficient ◽  
Computational Domain ◽  
Channel Deformations ◽  
Geological Surveys ◽  
Kuban River ◽  
The Stability ◽  
Protective Structures

In order to determine the possibility of using the method of mathematical modeling for making long-term forecasts of channel deformations of trunk line underwater crossing (TLUC) through water obstacles, a methodology for performing and analyzing the results of mathematical modeling of channel deformations in the TLUC zone across the Kuban River is considered. Within the framework of the work, the following tasks were solved: 1) the format and composition of the initial data necessary for mathematical modeling were determined; 2) the procedure for assigning the boundaries of the computational domain of the model was considered, the computational domain was broken down into the computational grid, the zoning of the computational domain was performed by the value of the roughness coefficient; 3) the analysis of the results of modeling the water flow was carried out without taking the bottom deformations into account, as well as modeling the bottom deformations, the specifics of the verification and calibration calculations were determined to build a reliable mathematical model; 4) considered the possibility of using the method of mathematical modeling to check the stability of the bottom in the area of TLUC in the presence of man-made dumping or protective structure. It has been established that modeling the flow hydraulics and structure of currents, making short-term forecasts of local high-altitude reshaping of the bottom, determining the tendencies of erosion and accumulation of sediments upstream and downstream of protective structures are applicable for predicting channel deformations in the zone of the TLUC. In all these cases, it is mandatory to have materials from engineering-hydro-meteorological and engineering-geological surveys in an amount sufficient to compile a reliable mathematical model.

A simulation apparatus for the experimental study of batch reactor control methods

1986 ◽  
Vol 51 (6) ◽  
pp. 1259-1267
Author(s):  
Josef Horák ◽  
Petr Beránek
Keyword(s):  
Experimental Study ◽  
Closed Loop ◽  
Dynamic Properties ◽  
Batch Reactor ◽  
Exothermic Reaction ◽  
Electric Heating ◽  
Batch Reactors ◽  
Exchange Area ◽  
The Stability ◽  
Methods Of Control

A simulation apparatus for the experimental study of the methods of control of batch reactors is devised. In this apparatus, the production of heat by an exothermic reaction is replaced by electric heating controlled by a computer in a closed loop; the reactor is cooled with an external cooler whose dynamic properties can be varied while keeping the heat exchange area constant. The effect of the cooler geometry on its dynamic properties is investigated and the effect of the cooler inertia on the stability and safety of the on-off temperature control in the unstable pseudostationary state is examined.

Turning Dynamics: Part 1 — Experimental Analysis

2012 ◽  
Author(s):  
Eric B. Halfmann ◽  
C. Steve Suh ◽  
N. P. Hung
Keyword(s):  
Instantaneous Frequency ◽  
Period Doubling ◽  
Displacement Sensor ◽  
Laser Displacement Sensor ◽  
Turning Process ◽  
Time Frequency ◽  
Spectral Components ◽  
Tool Vibrations ◽  
Exact Moment ◽  
The Stability

The workpiece and tool vibrations in a lathe are experimentally studied to establish improved understanding of cutting dynamics that would support efforts in exceeding the current limits of the turning process. A Keyence laser displacement sensor is employed to monitor the workpiece and tool vibrations during chatter-free and chatter cutting. A procedure is developed that utilizes instantaneous frequency (IF) to identify the modes related to measurement noise and those innate of the cutting process. Instantaneous frequency is shown to thoroughly characterize the underlying turning dynamics and identify the exact moment in time when chatter fully developed. That IF provides the needed resolution for identifying the onset of chatter suggests that the stability of the process should be monitored in the time-frequency domain to effectively detect and characterize machining instability. It is determined that for the cutting tests performed chatters of the workpiece and tool are associated with the changing of the spectral components and more specifically period-doubling bifurcation. The analysis presented provides a view of the underlying dynamics of the lathe process which has not been experimentally observed before.

Modal Analyses of Deployable Truss Structures Based on Shape Memory Polymer Composites

2016 ◽  
Vol 08 (07) ◽  
pp. 1640009 ◽  
Author(s):  
Fengfeng Li ◽  
Liwu Liu ◽  
Xin Lan ◽  
Tong Wang ◽  
Xiangyu Li ◽  
...  
Keyword(s):  
Finite Element ◽  
Shape Memory ◽  
Polymer Composites ◽  
Dynamic Properties ◽  
Low Cost ◽  
Shape Memory Polymer ◽  
Truss Structures ◽  
Modal Test ◽  
The Stability ◽  
Mechanical Devices

With large spatial deployable antennas used more widely, the stability of deployable antennas is attracting more attention. The form of the support structure is an important factor of the antenna’s natural frequency, which is essential to study to prevent the resonance. The deployable truss structures based on shape memory polymer composites (SMPCs) have made themselves feasible for their unique properties such as highly reliable, low-cost, light weight, and self-deployment without complex mechanical devices compared with conventional deployable masts. This study offers deliverables as follows: an establishment of three-longeron beam and three-longeron truss finite element models by using ABAQUS; calculation of natural frequencies and vibration modes; parameter studies for influence on their dynamic properties; manufacture of a three-longeron truss based on SMPC, and modal test of the three-longeron truss. The results show that modal test and finite element simulation fit well.

Research on the Performances of Self-Oscillation Linear Actuator and its Compensation

2012 ◽  
Vol 433-440 ◽  
pp. 7375-7380
Author(s):  
Fan Lin ◽  
Li Qiao ◽  
Yu Wang ◽  
Hui Liu
Keyword(s):  
Nonlinear Model ◽  
Servo System ◽  
The Self ◽  
Linear Actuator ◽  
Phase Lag ◽  
Phase Lead ◽  
The Stability ◽  
Lag Compensation

Base on constitution of the self-oscillation linear actuator which is a servo system for a gun launched missile, a nonlinear model was built. Though the experiment, the model is correct. This paper studied the stability, the self-oscillation's frequency and gain on this kind of servo system. On comparing phase-lead compensation and phase-lag compensation, the later is more suitable for this system. After testing, the lag regulator is designed for the system.

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