A New Approach to the Analysis of Machine-Tool System Stability Under Working Conditions

1977 ◽  
Vol 99 (3) ◽  
pp. 585-590 ◽  
Author(s):  
F. A. Burney ◽  
S. M. Pandit ◽  
S. M. Wu
Keyword(s):  
Machine Tool ◽  
Working Conditions ◽  
Cutting Speed ◽  
Stochastic Approach ◽  
Static Stability ◽  
Face Milling ◽  
System Stability ◽  
New Approach ◽  
Characteristic Roots ◽  
The Stability

A new stochastic approach is developed in this paper for analyzing the machine-tool system stability under working conditions. Mathematical models are fitted to the relative longitudinal cutter-workpiece displacement data recorded under different cutting conditions during the face-milling operation on a milling machine. The stability of the system is judged from the characteristic roots of these models. The variation in stability is examined versus both the cutting speed and the feed, and good results are obtained. It is shown that not only the dynamic but also the static stability can be ascertained. Furthermore, the stability of subsystems can also be determined. The significance of these results is discussed with special reference to on-line chatter control. The analysis of vibration signals produced by similar but evenly and unevenly spaced face milling cutters is presented as a vindication of the new approach.

A Stochastic Approach to Characterization of Machine Tool System Dynamics Under Actual Working Conditions

1976 ◽  
Vol 98 (2) ◽  
pp. 614-619 ◽  
Author(s):  
F. A. Burney ◽  
S. M. Pandit ◽  
S. M. Wu
Keyword(s):  
Machine Tool ◽  
Working Conditions ◽  
Stochastic Approach ◽  
Relative Displacement ◽  
Process Dynamics ◽  
Actual Working ◽  
Machine Tool Structure ◽  
Vertical Milling ◽  
Vertical Milling Machine ◽  
Tool Dynamics

The machine tool dynamics is evaluated under actual working conditions by using a time series technique. This technique develops mathematical models from only one signal, viz., the relative displacement between the cutter and the workpiece. Analysis of the experimental data collected on a vertical milling machine indicates that the new methodology is capable of characterizing the machine tool structure and the cutting process dynamics separately. Furthermore, it can also detect and quantify the interaction between these two subsystems.

scholarly journals Analysis of Transient Stability for Multimachine Power System

2020 ◽  
pp. 88-93
Keyword(s):  
Power System ◽  
Transient Stability ◽  
Power System Stability ◽  
Time Domain Analysis ◽  
Static Stability ◽  
System Stability ◽  
Reliable Operation ◽  
Machine System ◽  
Angle Stability ◽  
The Stability

The stability is an important guarantee for the safe and reliable operation of the power system, it is a decisive factor to limit the transmission distance and conveying capacity of the power system. Therefore, various measures must be taken to improve the system stability. The stability of the power system includes power angle stability, voltage stability and frequency stability. Among them, the power angle stability includes static stability and transient stability. Considering the importance of stability to the power system, the power system stability analysis methods and the measures to improve the power system stability is studied, so as to provide some useful reference for the safe and reliable operation of the power system. Generally, for multi-machine system transient stability becomes a major concern of wide power system due to load demand increasing day by day. In order to withstand disturbances with power quality issues requires evaluation of power system’s ability. There are many different kinds of methods for analysis of transient stability usually for multi-machine system. These methods include extended equal area criteria, time domain analysis and direct stability methods such as the transient energy function.

A Graphical Analysis of Regenerative Machine Tool Instability

1962 ◽  
Vol 84 (1) ◽  
pp. 103-111 ◽  
Author(s):  
J. P. Gurney ◽  
S. A. Tobias
Keyword(s):  
Machine Tool ◽  
Penetration Rate ◽  
Cutting Speed ◽  
Chip Thickness ◽  
Graphical Analysis ◽  
Mode Interaction ◽  
Thickness Variation ◽  
Machine Tool Structure ◽  
The Stability ◽  
Radial Drilling

A graphical method for the investigation of regenerative machine tool chatter is presented. The method is based on the harmonic response locus of the machine tool structure and allows the determination of the stable and unstable cutting speed ranges. The chip thickness variation effect as well as the penetration rate effect are taken into consideration. The method is illustrated by a number of examples relating to drilling or spot facing chatter arising on a radial drilling machine. The effects of mode interaction and of the penetration rate on the stability and on the variation of the chatter frequency are discussed. A critical assessment of the method is presented, in comparison with other methods available.

An Investigation of Stability Analysis of Face Milling of Cantilever Plates at Low Cutting Speeds

2018 ◽  
Vol 17 (02) ◽  
pp. 213-229 ◽  
Author(s):  
Joel Martins Crichigno Filho ◽  
João Fabio Bortolanza
Keyword(s):  
Cutting Speed ◽  
Milling Process ◽  
Face Milling ◽  
Stable Region ◽  
Depth Of Cut ◽  
Workpiece Surface ◽  
Process Damping ◽  
Stability Lobes ◽  
The Stability ◽  
Cutting Speeds

Considering the production requirement of workpiece optimization in order to reduce mass, the dynamic behavior of a workpiece can be affected. This factor can influence the performance of the milling process due to the occurrence of chatter vibrations. On the other hand, when the recommended cutting speed is relatively low, the tool rubs against the workpiece surface causing process damping. Consequently, the process becomes more stable and hence the depth of cut can be increased. In this paper, the stability of face milling of a cantilever plate at low cutting speed is investigated. The stability lobes diagram is determined numerically considering process damping. Cutting tests are conducted in order to verify the simulated results. An accelerometer is attached to the workpiece and its signal is measured and analyzed. Both workpiece surface and roughness are also investigated. The experimental results show a good agreement with the stability lobes diagram to predict the stable region under process damping. Hence, the depth of cut can be considerably increased, keeping the process stable at low cutting speeds.

Influence of Tool Nose Radius and Cutting Performance during Face Milling of Magnesium Alloy for Output Responses by Taguchi based Grey Relation Analysis

2021 ◽  
Vol 13 (2) ◽  
Author(s):  
Durai Kumaran ◽  
S.P. Sundar Singh Sivam ◽  
Harshavardhana Natarajan ◽  
P.R. Shobana Swarna Ratna
Keyword(s):  
Removal Rate ◽  
Cutting Speed ◽  
Face Milling ◽  
Machining Process ◽  
Tool Geometry ◽  
Depth Of Cut ◽  
Machining Parameters ◽  
New Approach ◽  
Grey Relational Grade ◽  
Grey Relational

In order to take advantage of the machining characteristics of magnesium, it is useful to consider recommended tool design and angles. The geometry of the tool can have a large influence on the machining process. Tool geometry can be used to aid with chip flow and clearance, reduce excessive heat generation, reduce tool build up, enable greater feed rates to be employed and improved tool life. This paper presents a new approach for the optimization of machining parameters on face milling of ZE41 with multiple responses based on orthogonal array with grey relational analysis. Machining tests are carried out by inserting 12 mm diameter of insert having 1 flute under dry condition. In this study, machining parameters namely cutting speed, feed and depth of cut and tool node radius are optimized with the considerations of multi responses such as surface roughness, material removal rate, tool wear and thrust force. A grey relational grade is obtained from the grey analysis. Based on the grey relational grade, optimum levels of parameters have been identified and significant contribution of parameters is determined by ANOVA. Confirmation test is conducted to validate the test result. Experimental results have shown that the responses in Machining process can be improved effectively through the new approach.

Stability and Performance Analysis of Time-Delayed Actuator Control Systems

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Bing Ai ◽  
Luis Sentis ◽  
Nicholas Paine ◽  
Song Han ◽  
Aloysius Mok ◽  
...  
Keyword(s):  
Time Delay ◽  
Time Windows ◽  
System Stability ◽  
Robotic Systems ◽  
Delay Systems ◽  
Physical Constraints ◽  
Characteristic Roots ◽  
And Performance ◽  
The Stability ◽  
Actuator Control

Time delay is a common phenomenon in robotic systems due to computational requirements and communication properties between or within high-level and low-level controllers as well as the physical constraints of the actuator and sensor. It is widely believed that delays are harmful for robotic systems in terms of stability and performance; however, we propose a different view that the time delay of the system may in some cases benefit system stability and performance. Therefore, in this paper, we discuss the influences of the displacement-feedback delay (single delay) and both displacement and velocity feedback delays (double delays) on robotic actuator systems by using the cluster treatment of characteristic roots (CTCR) methodology. Hence, we can ascertain the exact stability interval for single-delay systems and the rigorous stability region for double-delay systems. The influences of controller gains and the filtering frequency on the stability of the system are discussed. Based on the stability information coupled with the dominant root distribution, we propose one nonconventional rule which suggests increasing time delay to certain time windows to obtain the optimal system performance. The computation results are also verified on an actuator testbed.

Host-Guest Interactions on Electrode Surfaces for Immobilization of Molecular Catalysts

2020 ◽  
Author(s):  
Laurent Sévery ◽  
Jacek Szczerbiński ◽  
Mert Taskin ◽  
Isik Tuncay ◽  
Fernanda Brandalise Nunes ◽  
...  
Keyword(s):  
Aqueous Media ◽  
Heterogeneous Systems ◽  
Catalytic Systems ◽  
New Approach ◽  
Molecular Systems ◽  
Electrode Surfaces ◽  
Catalytic Surfaces ◽  
Oxide Electrodes ◽  
The Stability ◽  
Molecular Catalysts

The strategy of anchoring molecular catalysts on electrode surfaces combines the high selectivity and activity of molecular systems with the practicality of heterogeneous systems. The stability of molecular catalysts is, however, far less than that of traditional heterogeneous electrocatalysts, and therefore a method to easily replace anchored molecular catalysts that have degraded could make such electrosynthetic systems more attractive. Here, we apply a non-covalent “click” chemistry approach to reversibly bind molecular electrocatalysts to electrode surfaces via host-guest complexation with surface-anchored cyclodextrins. The host-guest interaction is remarkably strong and allows the flow of electrons between the electrode and the guest catalyst. Electrosynthesis in both organic and aqueous media was demonstrated on metal oxide electrodes, with stability on the order of hours. The catalytic surfaces can be recycled by controlled release of the guest from the host cavities and readsorption of fresh guest. This strategy represents a new approach to practical molecular-based catalytic systems.

scholarly journals Doubly fed induction generators to enhance inter-area damping based on a Robust controller: $${{\varvec{H}}}_{2}/{{\varvec{H}}}_{\infty }$$ Control

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Ali Goodarzi ◽  
Ali Mohammad Ranjbar ◽  
Moslem Dehghani ◽  
Mina GhasemiGarpachi ◽  
Mohammad Ghiasi
Keyword(s):  
Working Conditions ◽  
Reactive Power ◽  
Wind Farms ◽  
System Stability ◽  
Pole Placement ◽  
Linear Matrix ◽  
Robust Controller ◽  
Induction Generators ◽  
Doubly Fed ◽  
Oscillation Damping

AbstractIn this study, an auxiliary damping controller based on a robust controller considering the active and reactive power control loops for a doubly-fed induction generator for wind farms is proposed. The presented controller is able to improve the inter-area oscillation damping. In addition, the proposed controller applies only one accessible local signal as the input; however, it can improve the inter-area oscillation damping and, consequently the system stability for the various working conditions and uncertainties. The oscillatory modes of the system are appointed using the linear analysis. Then, the controller’s parameters are determined using the robust control approaches ($${H}_{\infty }/{H}_{2})$$ H ∞ / H 2 ) with the pole placement and linear matrix inequality method. The results of the modal analysis and time-domain simulations confirm that the controller develops the inter-area oscillation damping under the various working conditions and uncertainties.

Stability of Ring-Type MEMS Gyroscopes Subjected to Stochastic Angular Speed Fluctuation

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Samuel F. Asokanthan ◽  
Soroush Arghavan ◽  
Mohamed Bognash
Keyword(s):  
Angular Velocity ◽  
Degrees Of Freedom ◽  
Microelectromechanical Systems ◽  
Damping Ratio ◽  
Operating Conditions ◽  
System Stability ◽  
System Response ◽  
Ring Type ◽  
Mems Gyroscopes ◽  
The Stability

Effect of stochastic fluctuations in angular velocity on the stability of two degrees-of-freedom ring-type microelectromechanical systems (MEMS) gyroscopes is investigated. The governing stochastic differential equations (SDEs) are discretized using the higher-order Milstein scheme in order to numerically predict the system response assuming the fluctuations to be white noise. Simulations via Euler scheme as well as a measure of largest Lyapunov exponents (LLEs) are employed for validation purposes due to lack of similar analytical or experimental data. The response of the gyroscope under different noise fluctuation magnitudes has been computed to ascertain the stability behavior of the system. External noise that affect the gyroscope dynamic behavior typically results from environment factors and the nature of the system operation can be exerted on the system at any frequency range depending on the source. Hence, a parametric study is performed to assess the noise intensity stability threshold for a number of damping ratio values. The stability investigation predicts the form of threshold fluctuation intensity dependence on damping ratio. Under typical gyroscope operating conditions, nominal input angular velocity magnitude and mass mismatch appear to have minimal influence on system stability.

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