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.

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.

Dynamic Behavior of a Thin-Walled Cylindrical Workpiece During the Turning Process, Part 1: Cutting Process Simulation

2002 ◽  
Vol 124 (3) ◽  
pp. 562-568 ◽  
Author(s):  
K. Mehdi ◽  
J.-F. Rigal ◽  
D. Play
Keyword(s):  
Dynamic Behavior ◽  
Process Simulation ◽  
Point Of View ◽  
Cutting Process ◽  
Natural Phenomenon ◽  
Chatter Vibration ◽  
Turning Process ◽  
Chatter Vibrations ◽  
Cylindrical Workpiece ◽  
Thin Walled

From a practical point of view, in machining applications, chatter vibration constitutes a major problem during the cutting process. It is becoming increasingly difficult to suppress chatter during cutting at high speeds. Many investigators have regarded chatter vibrations as a “natural” phenomenon during the cutting process and a part of the process itself. In classical machining operations with thick-walled workpieces chatter vibrations occur when the cutting depth exceeds stability limits dependent on the machine tool. On the other hand, in the case of thin-walled cylindrical workpieces, chatter vibration problems are not so simple to formulate. The main purpose of this study is to qualify the dynamic behavior of a thin-walled workpiece during the turning process. It contains two parts: the cutting process simulation and the definition of experimental stability criteria. In the first part, a numerical model, which simulates the turning process of thin-walled cylindrical workpieces, is proposed. This model also permits obtaining workpiece responses to excitation generated by cutting forces. Finally, the stability of the process is discussed.

scholarly journals Analytical modeling of a thin-walled cylindrical workpiece during the turning process. Stability analysis of a cutting process

2017 ◽  
Vol 19 (8) ◽  
pp. 5825-5841 ◽  
Author(s):  
Artem Gerasimenko ◽  
Mikhail Guskov ◽  
Alexander Gouskov ◽  
Philippe Lorong ◽  
Alexander Shokhin
Keyword(s):  
Stability Analysis ◽  
Analytical Modeling ◽  
Cutting Process ◽  
Turning Process ◽  
Process Stability ◽  
Cylindrical Workpiece ◽  
Thin Walled

Analytical and experimental stability analysis of AU4G1 thin-walled tubular workpieces in turning process

2020 ◽  
Vol 234 (6-7) ◽  
pp. 1007-1018 ◽  
Author(s):  
Zied Sahraoui ◽  
Kamel Mehdi ◽  
Moez Ben-Jaber
Keyword(s):  
Stability Analysis ◽  
Feed Rate ◽  
Experimental Studies ◽  
Rake Angle ◽  
Machining Process ◽  
Structural Damping ◽  
Turning Process ◽  
Process Stability ◽  
Thin Walled ◽  
The Stability

The development of the manufacturing-based industries is principally due to the improvement of various machining operations. Experimental studies are important in researches, and their results are also considered useful by the manufacturing industries with their aim to increase quality and productivity. Turning is one of the principal machining processes, and it has been studied since the 20th century in order to prevent machining problems. Chatter or self-excited vibrations represent an important problem and generate the most negative effects on the machined workpiece. To study this cutting process problem, various models were developed to predict stable and unstable cutting conditions. Stability analysis using lobes diagrams became useful to classify stable and unstable conditions. The purpose of this study is to analyze a turning process stability using an analytical model, with three degrees of freedoms, supported and validated with experimental tests results during roughing operations conducted on AU4G1 thin-walled tubular workpieces. The effects of the tubular workpiece thickness, the feed rate and the tool rake angle on the machining process stability will be presented. In addition, the effect of an additional structural damping, mounted inside the tubular workpiece, on the machining process stability will be also studied. It is found that the machining stability process is affected by the tubular workpiece thickness, the feed rate and the tool rake angle. The additional structural damping increases the stability of the machining process and reduces considerably the workpiece vibrations amplitudes. The experimental results highlight that the dynamic behavior of turning process is governed by large radial deformations of the thin-walled workpieces. The influence of this behavior on the stability of the machining process is assumed to be preponderant.

scholarly journals Rotor-System Log-Decrement Identification Using Short-Time Fourier-Transform Filter

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Qihang Li ◽  
Weimin Wang ◽  
Lifang Chen ◽  
Dan Sun
Keyword(s):  
Fourier Transform ◽  
Large Scale ◽  
Stability Margin ◽  
Element Model ◽  
Operating Conditions ◽  
Short Time Fourier Transform ◽  
Stability Parameters ◽  
Identification Method ◽  
The Stability ◽  
Short Time

With the increase of the centrifugal compressor capability, such as large scale LNG and CO2reinjection, the stability margin evaluation is crucial to assure the compressor work in the designed operating conditions in field. Improving the precision of parameter identification of stability is essential and necessary as well. Based on the time-varying characteristics of response vibration during the sine-swept process, a short-time Fourier transform (STFT) filter was introduced to increase the signal-noise ratio and improve the accuracy of the estimated stability parameters. A finite element model was established to simulate the sine-swept process, and the simulated vibration signals were used to study the filtering effect and demonstrate the feasibility to identify the stability parameters by using Multiple-Input and Multiple-Output system identification method that combines the prediction error method and instrumental variable method. Simulation results show that the identification method with STFT filter improves the estimated accuracy much well and makes the curves of frequency response function clearer. Experiment was carried out on a test rig as well, which indicates the identification method is feasible in stability identification, and the results of experiment indicate that STFT filter works very well.

A bead laying algorithm for enhancing the stability and dynamic behavior of thin-walled structures

2012 ◽  
Vol 223 (8) ◽  
pp. 1621-1631 ◽  
Author(s):  
C. Bilik ◽  
D. H. Pahr ◽  
F. G. Rammerstorfer
Keyword(s):  
Dynamic Behavior ◽  
Thin Walled Structures ◽  
Thin Walled ◽  
The Stability

scholarly journals ANALYSIS OF THE CONDITIONS OF OCCURRENCE AND SUPPRESSION OF LATERAL VIBRATIONS IN MICROWAVE POWER FETS

2020 ◽  
Vol 258 (3) ◽  
pp. 4-21
Author(s):  
V. L. Aronov ◽  
E. M. Savchenko ◽  
D. M. Moseykin ◽  
A. D. Pershin ◽  
D. G. Drozdov
Keyword(s):  
Experimental Studies ◽  
Element Model ◽  
Excitation Power ◽  
Point Of View ◽  
Operating Conditions ◽  
Stability Factor ◽  
Lateral Instability ◽  
Wide Range ◽  
Amplifier Stage ◽  
The Stability

Lateral instability is inherent in power transistors structures, consisting of several simple transistors connected in parallel. The large number of transistor elements complicates the analysis of such instability. The introduction of suppressing resistors makes it possible to prevent the occurrence of lateral oscillations, however there are no unambiguous criteria for achieving stability this way. The matter is further complicated by the fact that transistor exhibits nonlinear operation in a typical amplifier stage, and the operating conditions in many cases correspond to a relatively wide range of frequencies. In this paper, we present an analysis of lateral instability of a power amplifier stage, created on a basis of modern GaN field-effect transistor (FET). We had designed all dies and circuits for this FET. The main feature of the analysis is that we carried it out in the time domain, which made possible to estimate the stability of the stage not only under the excitation power pulse, but also after the end of the pulse. Our approach makes it possible to assess the stability of the amplifier between the excitation pulses, which is very important from the operational point of view. We calculated the estimates of operational stability and stability factor using a simplified transistor model, with the multi-element model reduced to a two-element model. Nevertheless, the results of the estimates retain their significance in real conditions, when the introduction of suppressing resistors creates a significant margin of stability, including the actual operating frequency band of the stage. To date, the data we have obtained after the manufacture of the samples only partially confirms the calculated estimates, due to the complexity of managing the experimental studies. However, there are no recorded results, which deny our estimates for the model.

Analytic Method of Stability of Rigid Frame Bridge with Double-Limb Thin-Walled Piers

2014 ◽  
Vol 501-504 ◽  
pp. 1136-1139
Author(s):  
Xiu Lan Wang ◽  
Wen Qiang Chen
Keyword(s):  
Element Model ◽  
Calculation Error ◽  
Analytic Method ◽  
Dead Load ◽  
Buckling Loads ◽  
Effective Height ◽  
Rigid Frame ◽  
Thin Walled ◽  
The Stability ◽  
Rigid Frame Bridge

Based on the stability theory of column ,this paper did research on the solving methods of buckling eigenvalue when the rigid frame bridge was subjected to dead load . When solving the critical failure force, you could consider the height of piers as the effective height, consider the sum of the loads of upper structure and half of the weight of the piers as the equivalent buckling loads. Finite element model was created for verifying the solving method introduced in this paper. The results shows that in the maximum cantilever phase , the calculation error of buckling eigenvalue was decreased as the height of piers was increased ; the method in this paper was more accurate on the completed bridge stage . When the height of two piers was different, you can calculate each piers buckling eigenvalue, the buckling eigenvalue of the whole bridge was the average of every pier.

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.

Sign in / Sign up

Export Citation Format

Share Document