Experimental Chatter Modeling of Milling Operations

2007 ◽  
Author(s):  
Giuseppe Catania ◽  
Nicolo` Mancinelli
Keyword(s):  
Ad Hoc ◽  
Dynamical Behavior ◽  
Measurement Data ◽  
Period Doubling ◽  
Experimental Tests ◽  
Cutting Parameters ◽  
Operating Conditions ◽  
Depth Of Cut ◽  
Wide Range ◽  
Excited Vibration

This study refers to the investigation on the critical operating condition occurring on high productivity milling machines, known as chatter. This phenomenon is generated by a self-excited vibration, associated with a loss of stability of the system, causing reduced productivity, poor surface finish and noise. This study consists of the theoretical and experimental modeling of machining chatter conditions, in order to develop a real-time monitoring system able to diagnose the occurrence of chatter in advance and to dynamically modify the cutting parameters for process optimization. A prototype NC 3-axis milling machine was ad hoc realized to accomplish this task. The machine was instrumented by a dynamometer table, and a series of accelerometer sensors were mounted in the proximity of the tool spindle and the workpiece. An analytical model was developed, taking into account the periodic cutting force arising during interrupted cutting operation in milling. The system dynamical behavior was described by means of a set of delay differential equations with periodic coefficients. The stability of this system was analyzed by the semi discretization approach based on the Floquet theory. Lobe stability charts were evaluated and associated with frequency diagrams. Two chatter types were analytically and experimentally detected: period-doubling bifurcations and secondary Hopf bifurcations. Measurement data were acquired and analyzed in the time and frequency domain. Several tests were conducted in a wide range of operating conditions, such as radial immersion, depth of cut and spindle speeds and using different tools. Results are reported showing agreement between the numerical analysis and the related experimental tests.

scholarly journals Multibody dynamic modelling of a direct wind turbine drive train

2019 ◽  
Vol 44 (5) ◽  
pp. 519-547
Author(s):  
Saeed Asadi ◽  
Håkan Johansson
Keyword(s):  
Wind Turbine ◽  
Measurement Data ◽  
Dynamic Modelling ◽  
Simulation Software ◽  
Operating Conditions ◽  
Drive Train ◽  
Operational Experience ◽  
Main Bearing ◽  
Wide Range ◽  
Turbine Drive

Wind turbines normally have a long operational lifetime and experience a wide range of operating conditions. A representative set of these conditions is considered as part of a design process, as codified in standards. However, operational experience shows that failures occur more frequently than expected, the costlier of these including failures in the main bearings and gearbox. As modern turbines are equipped with sophisticated online systems, an important task is to evaluate the drive train dynamics from online measurement data. In particular, internal forces leading to fatigue can only be determined indirectly from other locations’ sensors. In this contribution, a direct wind turbine drive train is modelled using the floating frame of reference formulation for a flexible multibody dynamics system. The purpose is to evaluate drive train response based on blade root forces and bedplate motions. The dynamic response is evaluated in terms of main shaft deformation and main bearing forces under different wind conditions. The model was found to correspond well to a commercial wind turbine system simulation software (ViDyn).

Life Prediction of Cutting Tool by the Workpiece Cutting Condition

2011 ◽  
Vol 223 ◽  
pp. 554-563 ◽  
Author(s):  
Noemia Gomes de Mattos de Mesquita ◽  
José Eduardo Ferreira de Oliveira ◽  
Arimatea Quaresma Ferraz
Keyword(s):  
Cutting Tool ◽  
Cutting Tools ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Operating Conditions ◽  
Production Costs ◽  
Depth Of Cut ◽  
Cutting Condition ◽  
Workpiece Material ◽  
The Cost

Stops to exchange cutting tool, to set up again the tool in a turning operation with CNC or to measure the workpiece dimensions have direct influence on production. The premature removal of the cutting tool results in high cost of machining, since the parcel relating to the cost of the cutting tool increases. On the other hand the late exchange of cutting tool also increases the cost of production because getting parts out of the preset tolerances may require rework for its use, when it does not cause bigger problems such as breaking of cutting tools or the loss of the part. Therefore, the right time to exchange the tool should be well defined when wanted to minimize production costs. When the flank wear is the limiting tool life, the time predetermination that a cutting tool must be used for the machining occurs within the limits of tolerance can be done without difficulty. This paper aims to show how the life of the cutting tool can be calculated taking into account the cutting parameters (cutting speed, feed and depth of cut), workpiece material, power of the machine, the dimensional tolerance of the part, the finishing surface, the geometry of the cutting tool and operating conditions of the machine tool, once known the parameters of Taylor algebraic structure. These parameters were raised for the ABNT 1038 steel machined with cutting tools of hard metal.

scholarly journals Review on Machining of Aluminium Metal Matrix Composites

2014 ◽  
Vol 11 (2) ◽  
pp. 114-120 ◽  
Author(s):  
Pushpendra Jain ◽  
S Soni ◽  
Prashant Baredar
Keyword(s):  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Cutting Parameters ◽  
Operating Conditions ◽  
Machining Parameters ◽  
Matrix Composites ◽  
Wide Range ◽  
Attractive Option ◽  
Superior Mechanical Properties ◽  
Aluminium Metal

Metal matrix composites have superior mechanical properties in comparison to metals over a wide range of operating conditions. This make them an attractive option in replacing metals for various engineering applications. This paper provides a literature review, on machining of Aluminium metal matrix composites (AMMC)especially the particle reinforced Aluminium metal matrix composites. This paper is an attempt to give brief account of recent work to predict cutting parameters &surface generated in AMMC.By suitably selecting the machining parameters, machining of AMMC can be made economical.

scholarly journals Uso del procesamiento digital de imágenes para la extracción de datos de medidas experimentales publicados en formato gráfico

2019 ◽  
pp. 6-16
Author(s):  
Edebaldo Peza-Ortiz ◽  
José Bernardo Torres-Valle ◽  
Enrique García-Trinidad ◽  
Alma Delia González Ramos-Gora
Keyword(s):  
Technological Development ◽  
Data Extraction ◽  
Measurement Data ◽  
Main Tool ◽  
Experimental Tests ◽  
Laboratory Equipment ◽  
Strain Behavior ◽  
Wide Range ◽  
Pixel Grouping ◽  
Mathematical Operations

In this article, we propose a method as an alternative to obtain experimental measurement data, in the absence of laboratory equipment to perform tests, in a suitable format to perform mathematical operations in order to use them as information to validate: hypotheses, models constitutive and / or research theories focused on technological development. The proposed method uses as a main tool the image segmentation technique by region growth by pixel grouping and the normalization of the coordinates of the positions of the pixels extracted to the axis scale in the corresponding figure. The segmentation of the image separates the coordinates of the pixels that form the axes and the curves, the coordinates of the pixels of the curves are normalized to the scale of the axes. The method is tested with images of the result of experimental tests of stress-strain behavior recovered from [1]. The results of the data extraction are plotted and the averages of each curve extracted as well as the standard deviation are obtained. It is verified that the data obtained can be used to corroborate or support hypotheses in a wide range of investigations.

Complex Dynamics in a Harmonically Excited Lennard-Jones Oscillator: Microcantilever-Sample Interaction in Scanning Probe Microscopes1

1998 ◽  
Vol 122 (1) ◽  
pp. 240-245 ◽  
Author(s):  
M. Basso ◽  
L. Giarre´ ◽  
M. Dahleh ◽  
I. Mezic´
Keyword(s):  
Parameter Space ◽  
Complex Dynamics ◽  
Chaotic Behavior ◽  
Dynamical Behavior ◽  
Period Doubling ◽  
Operating Conditions ◽  
Invariant Sets ◽  
Jones Potential ◽  
Lennard Jones ◽  
Atomic Force

In this paper we model the microcantilever-sample interaction in an atomic force microscope (AFM) via a Lennard-Jones potential and consider the dynamical behavior of a harmonically forced system. Using nonlinear analysis techniques on attracting limit sets, we numerically verify the presence of chaotic invariant sets. The chaotic behavior appears to be generated via a cascade of period doubling, whose occurrence has been studied as a function of the system parameters. As expected, the chaotic attractors are obtained for values of parameters predicted by Melnikov theory. Moreover, the numerical analysis can be fruitfully employed to analyze the region of the parameter space where no theoretical information on the presence of a chaotic invariant set is available. In addition to explaining the experimentally observed chaotic behavior, this analysis can be useful in finding a controller that stabilizes the system on a nonchaotic trajectory. The analysis can also be used to change the AFM operating conditions to a region of the parameter space where regular motion is ensured. [S0022-0434(00)01401-5]

An Innovative Device for Passive Control of Surge in Industrial Compression Systems

2000 ◽  
Author(s):  
Gianmario L. Arnulfi ◽  
Pietro Giannattasio ◽  
Diego Micheli ◽  
Piero Pinamonti
Keyword(s):  
Passive Control ◽  
Experimental Tests ◽  
Control Device ◽  
Operating Conditions ◽  
Compression System ◽  
Multi Stage ◽  
Lumped Parameter ◽  
Wide Range ◽  
Optimal Values ◽  
Parameter Approach

The present paper reports a numerical-experimental study on the dynamic behaviour of a compression system based on a multi-stage centrifugal blower and fitted with an innovative device for the dynamic suppression of surge instability. The control device is of passive type and is based on the aeroelastic coupling of the basic compression system with a hydraulic oscillator. The controlled system is modelled at first by using a non-linear lumped parameter approach. The simulated system dynamics within a wide range of operating conditions allows a parametric analysis to be performed and the optimal values of the control parameters to be singled out. Such optimal values are then used to design the hydraulic oscillator, which results in a technically feasible and very simple configuration. Finally, experimental tests are carried out on the compression plant with and without the passive control device, which demonstrate the effectiveness of the proposed control system in suppressing surge instabilities, at least within the limits predicted by the numerical simulation.

scholarly journals Fuzzy Supervisor Approach Design Based-Switching Controller for Pumping Station: Experimental Validation

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Wael Chakchouk ◽  
Chiheb Ben Regaya ◽  
Abderrahmen Zaafouri ◽  
Anis Sellami
Keyword(s):  
Tracking Error ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Pumping Station ◽  
Wide Range ◽  
Pi Controllers ◽  
Switching Controller ◽  
Hydraulic Process ◽  
Fuzzy Pd ◽  
Fuzzy Supervisor

This paper proposes a discrete-time switching controller strategy for a hydraulic process pumping station. The proposed solution leads to improving control system performances with two tests: combination of Fuzzy-PD and PI controllers and Fuzzy-PID and PI controllers. The proposed design methodology is based on accurate model for pumping station (PS), which is developed in previous works using Fuzzy-C Means (FCM) algorithm. The control law design is based on switching control; a fuzzy supervisor manages the switching from one to another and regulates the rate of participation of each order, in order to satisfy various objectives of a stable pumping station like the asymptotic stability of the tracking error. To validate the proposed solution, experimental tests are made and analyzed. Compared to the conventional PI and fuzzy logic (FL) approaches, the results show that the switching controller allows exhibiting excellent transient response over a wide range of operating conditions and especially is easier to be implemented in practice.

Experimental and Numerical Investigation of the Flow in a LP Industrial Steam Turbine With Part-Span Connectors

2015 ◽  
Author(s):  
M. Häfele ◽  
C. Traxinger ◽  
M. Grübel ◽  
M. Schatz ◽  
D. M. Vogt ◽  
...  
Keyword(s):  
Flow Field ◽  
Steam Turbine ◽  
Numerical Study ◽  
Resonance Condition ◽  
Three Dimensional ◽  
Measurement Data ◽  
Detailed Comparison ◽  
Operating Conditions ◽  
Engineering Practice ◽  
Wide Range

An experimental and numerical study on the flow in a three stage low pressure (LP) industrial steam turbine is presented and analyzed. The investigated LP section features conical friction bolts in the last and a lacing wire in the penultimate rotor blade row. These part-span connectors (PSC) allow safe turbine operation over an extremely wide range and even in blade resonance condition. However, additional losses are generated which affect the performance of the turbine. In order to capture their impact on the flow field, extensive measurements with pneumatic multi-hole probes in an industrial steam turbine test rig have been carried out. State-of-the-art three-dimensional CFD applying a non-equilibrium steam (NES) model is used to examine the aero-thermodynamic effects of the PSC on the wet steam flow. A detailed comparison between measurement data and CFD results is performed for several operating conditions. The investigation shows that the applied CFD model is able to capture the three-dimensional flow field in LP steam turbine blading with PSC and the total pressure reduction due to the PSC with a generally good agreement to measured values and is therefore sufficient for engineering practice.

Grain-Workpiece Interaction Study of Grinding Process through Single Grain Cutting Simulation

2010 ◽  
Vol 431-432 ◽  
pp. 269-272 ◽  
Author(s):  
Lan Yan ◽  
Zhi Xiong Zhou ◽  
Feng Jiang ◽  
X.K. Li ◽  
Yi Ming Rong
Keyword(s):  
Cutting Force ◽  
Removal Rate ◽  
Cutting Parameters ◽  
Depth Of Cut ◽  
Grinding Wheel ◽  
Grinding Process ◽  
Micro Cutting ◽  
Wide Range ◽  
Single Grain ◽  
Workpiece Interaction

Grinding process can be considered as micro-cutting processes with the irregular abrasive grains on the surface of grinding wheel. The grain-workpiece interface directly forms the workpiece surface. Therefore, the study of the grain-workpiece interaction through micro-cutting analysis becomes necessary. But the experiments for single grain cutting are difficult to perform. Aimed at this problem, single grain cutting simulations of AISI D2 steel with a wide range of cutting parameters have been carried out with AdvantEdgeTM in this study. The effect of cutting parameters on cutting force, specific cutting force, material removal rate and critical depth of cut has been analyzed.

How Bulk Modulus Errors Can Affect Leak Detection

1996 ◽  
Author(s):  
Henry H. Rachford ◽  
Andrew Wike
Keyword(s):  
Bulk Modulus ◽  
Measurement Data ◽  
Leak Detection ◽  
Operating Conditions ◽  
Time Data ◽  
Transient Model ◽  
Property Data ◽  
Wide Range ◽  
Fluid Properties ◽  
On Line

Liquid pipeline operators look to leak detection systems to provide continuous surveillance of their pipelines across a wide range of operating conditions; this is particularly the case for batch pipelines. Operators frequently anticipate that on-line transient modeling systems can satisfy this requirement, which they can, but have little exposure to the on-line measurement data requirements of such systems. There can be a mistaken focus on improving the quality of the real-time data normally available to facilitate pipeline operations, without due regard to providing the measurement data that the model needs. Pipeline operators are normally not concerned with a detailed characterization of fluid properties, other than in the most general sense regarding the susceptibility of adjacent fluids to mix at their interface. This paper illustrates how the lack of reliable fluid property data (specifically, bulk modulus data) can substantially impede the effectiveness of a transient model charged with the task of leak detection.

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