scholarly journals Implicit Subspace Iteration to Improve the Stability Analysis in Grinding Processes

2020 ◽  
Vol 10 (22) ◽  
pp. 8203 ◽  
Author(s):  
Jorge Alvarez ◽  
Mikel Zatarain ◽  
David Barrenetxea ◽  
Jose Ignacio Marquinez ◽  
Borja Izquierdo
Keyword(s):  
Stability Analysis ◽  
Dynamic Stability ◽  
Time Domain ◽  
Grinding Processes ◽  
Subspace Iteration ◽  
Efficient Calculation ◽  
Chatter Vibrations ◽  
Stability Maps ◽  
Iteration Methods ◽  
The Stability

An alternative method is devised for calculating dynamic stability maps in cylindrical and centerless infeed grinding processes. The method is based on the application of the Floquet theorem by repeated time integrations. Without the need of building the transition matrix, this is the most efficient calculation in terms of computation effort compared to previously presented time-domain stability analysis methods (semi-discretization or time-domain simulations). In the analyzed cases, subspace iteration has been up to 130 times faster. One of the advantages of these time-domain methods to the detriment of frequency domain ones is that they can analyze the stability of regenerative chatter with the application of variable workpiece speed, a well-known technique to avoid chatter vibrations in grinding processes so the optimal combination of amplitude and frequency can be selected. Subspace iteration methods also deal with this analysis, providing an efficient solution between 27 and 47 times faster than the abovementioned methods. Validation of this method has been carried out by comparing its accuracy with previous published methods such as semi-discretization, frequency and time-domain simulations, obtaining good correlation in the results of the dynamic stability maps and the instability reduction ratio maps due to the application of variable speed.

Dynamic Stability of FPSO-Shuttle Systems: An Analytical Procedure and Practical Results

2002 ◽  
Author(s):  
Ge´rson B. Matter ◽  
Joel S. Sales ◽  
Sergio H. Sphaier
Keyword(s):  
Dynamic Stability ◽  
Deep Water ◽  
Dynamic Systems ◽  
Time Domain ◽  
Equilibrium Position ◽  
Analytical Procedure ◽  
Time Domain Analysis ◽  
The Stability ◽  
The Time Domain ◽  
Floating Systems

The paper deals with the dynamics of floating systems (FPSO units) moored in deep water in the presence of currents. The offloading operation is carried out in a tandem arrangement from the FPSO to a Shuttle ship of lesser capacity. According to the classical theory of dynamic systems, a study of the behavior of floating units is performed by determining the equilibrium position and then analyzing the stability around this position. The time domain analysis is also used to compare the results. This procedure is extended to the case of systems in a spread mooring configuration and with turret.

Stability Analysis of On-Board Friction Modifier Systems at the Wheel–Rail Interface

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
C. P. Sharma ◽  
A. Srikantha Phani
Keyword(s):  
Stability Analysis ◽  
Frictional Contact ◽  
Strong Dependence ◽  
Friction Modifier ◽  
Design Engineers ◽  
Design Changes ◽  
Linearized Stability ◽  
Stability Maps ◽  
And Performance ◽  
The Stability

Friction control at the wheel–rail interface, using on-board solid stick friction modifier systems can lead to enhanced track life, reduced wear, and increased fuel economy in railroads. Frictional contact between the solid stick and the railway wheel itself can potentially cause vibrations within the modifier systems, influencing their stability and performance. A frequency domain linearized stability analysis of the state of steady sliding at the frictional contact between the solid stick and the wheel is performed. The proposed approach relies on individual frequency response functions (FRFs) of the wheel and the applicator–bracket subsystems of the on-board friction modifier. Stability characteristics of three representative bracket designs are qualitatively compared, using the FRFs generated by their respective finite element (FE) models. The FE models are validated by comparing the predicted natural frequencies with corresponding experimentally measured values on a full wheel test rig (FWTR) facility. The validated FE models are then used to compute stability maps which delineate stable and unstable regions of operation in the design parameter space, defined by train speed, angle of applicator, friction coefficient, and bracket design. Strong dependence of stability upon the bracket designs is observed. The methodology developed here can be used by design engineers to assess the effectiveness of design changes on the stability of the applicator–bracket assembly in a virtual environment—thus avoiding costly retrofitting and prototyping. Directions for further model refinement and testing are provided.

scholarly journals Experimental and simulated milling stability tests

Mechanik ◽  
2017 ◽  
Vol 90 (11) ◽  
pp. 965-967
Author(s):  
Piotr Andrzej Bąk ◽  
Krzysztof Jemielniak
Keyword(s):  
Numerical Simulation ◽  
Stability Analysis ◽  
Time Domain ◽  
Cutting Parameters ◽  
Milling Machine ◽  
Machined Surface ◽  
Simulation Results ◽  
The Stability ◽  
The Time Domain

Self-excited vibrations significantly reduce the milling productivity, deteriorate the quality of machined surface and tool life. One of the ways to avoid these vibrations is to modify the cutting parameters based on the stability analysis results. A method of numerical simulation of self-excited vibrations in the time domain can be used for this purpose. A comparison of numerical simulation results with those from experiments conducted using a milling machine is presented. The results confirm the correctness of applied modeling.

Analysis and Experimental Investigation of the Stability of Intershaft Squeeze Film Dampers—Part 2: Control of Instability

1978 ◽  
Vol 100 (3) ◽  
pp. 558-562 ◽  
Author(s):  
D. H. Hibner ◽  
P. N. Bansal ◽  
D. F. Buono
Keyword(s):  
Experimental Investigation ◽  
Stability Analysis ◽  
Shear Deformation ◽  
System Stability ◽  
Squeeze Film ◽  
Viscous Damper ◽  
Test Rig ◽  
Squeeze Film Dampers ◽  
Stability Maps ◽  
The Stability

The results of an analytical and experimental investigation showing the existence of an intershaft viscous damper instability were presented in reference [1]. In the present investigation, a more comprehensive stability analysis is used to study the stability of the test rig which incorporates a modified intershaft bearing support. The analysis is applicable to large multi-mass, rotor-bearing systems and includes the effects of gyroscopic moments, shear deformation, bearing support flexibility, and damping. The results of the stability analysis are presented in the form of system stability maps which clearly indicate the effectiveness of the modification in improving the instability onset speed of the system. Also presented are the results of an experimental investigation which substantiate the analytical predictions.

Dynamic Stability Analysis of the Tower Structure of Construction Elevators

2013 ◽  
Vol 459 ◽  
pp. 646-649
Author(s):  
Xian Rong Qin ◽  
Ying Hong ◽  
Peng Yue ◽  
Qing Zhang ◽  
Yuan Tao Sun
Keyword(s):  
Stability Analysis ◽  
Stress Field ◽  
Dynamic Stability ◽  
Transient Analysis ◽  
Stress Effect ◽  
Construction Process ◽  
Moving Loads ◽  
Eigenvalue Method ◽  
Tower Structure ◽  
The Stability

This paper proposed a method of dynamic stability analysis for the tower structure of construction elevators based on dynamic eigenvalue method. The method employed the time frozen formulation to model the problem, and the stress field from transient analysis was utilized to simulate the pre-stress effect of buckling analysis. The proposed method was applied to estimate the dynamic stability of the tower structure of construction elevators under moving loads, and the results suggest that high coefficients of lateral load and inclined tower structure will dramatically reduce the stability of the elevator in the construction process.

Dynamic Stability Analysis of Defective Piles under Vertical Harmonic Load

2013 ◽  
Vol 477-478 ◽  
pp. 592-595
Author(s):  
Xian Guang Ni
Keyword(s):  
Stability Analysis ◽  
Dynamic Stability ◽  
Critical Frequency ◽  
Harmonic Load ◽  
Heterogeneous Soil ◽  
Engineering Problems ◽  
Practical Engineering ◽  
The Stability ◽  
Dynamical Function

We established the computational mode for defective piles based on practical engineering problems,and studied the stability of the defective pile in the heterogeneous soil under vertical harmonic loads. We established the dynamical function based on the principle of Energy and Hamilton, and abtained the expressions of critical frequency of defective piles.The results show that, the instability of the defective piles relate to the degree of defect and the location of defect.

Numerical Analysis of Dynamic Stability of Elastic Truss Structures

1998 ◽  
Vol 13 (2) ◽  
pp. 75-81 ◽  
Author(s):  
Qi-Lin Zhang ◽  
Udo Peil
Keyword(s):  
Stability Analysis ◽  
Numerical Analysis ◽  
Dynamic Stability ◽  
Time Domain ◽  
Truss Structures ◽  
Equilibrium Equations ◽  
Numerical Examples ◽  
Motion Trajectories ◽  
Dynamic Excitations ◽  
Energy Increment

In this paper the concept of energy increment map is presented for stability judgement of elastic truss structures under arbitrary dynamic excitations. The modified member theory is adopted to establish the equilibrium equations of the structures. The motion trajectories of structures are numerically solved in time domain and the corresponding stability states are studied according to the energy increment map. Numerical examples show that the method of this paper can lead to satisfactory results in dynamic stability analysis of elastic truss structures.

Effect of Aerodynamic Loads on Dynamic Stability of Slender Launch Vehicle Subjected to an End Rocket Thrust

2002 ◽  
Author(s):  
Tsukasa Ohshima ◽  
Yoshihiko Sugiyama
Keyword(s):  
Stability Analysis ◽  
Dynamic Stability ◽  
Longitudinal Axis ◽  
Launch Vehicle ◽  
Aerodynamic Load ◽  
Aerodynamic Loads ◽  
Eigen Values ◽  
Rocket Thrust ◽  
The Stability ◽  
Free Beam

This paper deals with dynamic stability of a slender launch vehicle subjected to aerodynamic loads and an end rocket thrust. The flight vehicle is simplified into a uniform free-free beam subjected to an end follower thrust. Two types of aerodynamic loads are assumed in the stability analysis. Firstly, it is assumed that two concentrated aerodynamic loads act on the flight body at its nose and tail. Secondly, to take account of effect of unsteady flow due to motion of a flexible flight body, aerodynamic load is estimated by the slender body approximation. Extended Hamilton’s principle is applied to the considered beam for deriving the equation of motion. Application of FEM yields standard eigen-value problem. Dynamic stability of the beam is determined by the sign of the real part of the complex eigen-values. If aerodynamic loads are concentrated loads that act on the flight body at its nose and tail, the flutter thrust decreases by about 10% in comparison with the flutter thrust of free-free beam subjected only to an end follower thrust. If aerodynamic loads are distributed along the longitudinal axis of the flight body, the flutter thrust decreases by about 70% in comparison with the flutter thrust of free-free beam under an end follower thrust. It is found that the flutter thrust is reduced considerably if the aerodynamic loads are taken into account in addition to an end rocket thrust in the stability analysis of slender rocket vehicle.

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