Analytical Modeling of Chatter Stability in Turning and Boring Operations—Part II: Experimental Verification

2007 ◽  
Vol 129 (4) ◽  
pp. 733-739 ◽  
Author(s):  
Emre Ozlu ◽  
Erhan Budak
Keyword(s):  
Satisfactory Agreement ◽  
Experimental Verification ◽  
Analytical Modeling ◽  
Stability Limit ◽  
Experimental Results ◽  
Chatter Stability ◽  
Nose Radius ◽  
The Stability ◽  
Flexible Component ◽  
Cutting System

In this part of the paper series, chatter experiments are conducted in order to verify the proposed stability models presented in the first part (Ozlu, E., and Budak, E., 2007, ASME J. Manuf. Sci. Eng., 129(4), pp. 726–732). Turning and boring chatter experiments are conducted for the cases where the tool or the workpiece is the most flexible component of the cutting system. In addition, chatter experiments demonstrating the effect of the insert nose radius on the stability limit are presented. Satisfactory agreement is observed between the analytical predictions and the experimental results.

scholarly journals Dynamic Modeling and Cutting Stability of Rotating Tapered Composite Cutter Bar considering Material Damping

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Yuhuan Zhang ◽  
Ren Yongsheng ◽  
Bole Ma ◽  
Jinfeng Zhang
Keyword(s):  
Constitutive Relations ◽  
Equations Of Motion ◽  
Beam Theory ◽  
Chatter Stability ◽  
Differential Motion ◽  
Chatter Suppression ◽  
Fixed Type ◽  
The Stability ◽  
The Galerkin Method ◽  
Cutting System

Traditional milling cutter bars are generally made up of metals and exhibit poor capacity of chatter suppression. This study proposes an anisotropic composites tapered cutter bar for increasing natural frequency and damping and finally achieves the goal of enhancing chatter stability. Based on Hamilton principle and Euler–Bernoulli beam theory, the partial differential motion equations of the cutting system with a 3D rotating tapered composite cutter bar are established. Next, using the Galerkin method, the equations of motion are discretized so as to derive ordinary differential equations. In the model, damping modeling of the composite cutter bar is achieved theoretically by using damping dissipation constitutive relations for viscoelastic composites. Moreover, by introducing the rotating effect of the 3D cutter bar in the 2-DOF analytical model of stability analysis first proposed for a fixed-type cutter bar, an improved prediction model is developed and used to solve the stability lobes of the cutting system in the frequency domain analytically. Furthermore, the influences of the gyroscopic effect, material, ply angle, stacking sequence, and taper ratio on chatter stability are also discussed.

A New Metric for Automated Stability Identification in Time Domain Milling Simulation

2016 ◽  
Vol 138 (7) ◽  
Author(s):  
Andrew Honeycutt ◽  
Tony L. Schmitz
Keyword(s):  
Time Domain ◽  
Forced Vibration ◽  
Stability Limit ◽  
Experimental Results ◽  
The Other ◽  
Sampled Data ◽  
A Value ◽  
Milling Simulation ◽  
The Stability ◽  
Over Time

A new metric is presented to automatically establish the stability limit for time domain milling simulation signals. It is based on periodically sampled data. Because stable cuts exhibit forced vibration, the sampled points repeat over time. Periodically sampled points for unstable cuts, on the other hand, do not repeat with each tooth passage. The metric leverages this difference to define a numerical value of nominally zero for a stable cut and a value greater than zero for an unstable cut. The metric is described and is applied to numerical and experimental results.

scholarly journals A Multi-Curvature, Variable Stiffness Soft Gripper for Enhanced Grasping Operations

Actuators ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 316
Author(s):  
Eun Jeong Song ◽  
Jung Soo Lee ◽  
Hyungpil Moon ◽  
Hyouk Ryeol Choi ◽  
Ja Choon Koo
Keyword(s):  
Degrees Of Freedom ◽  
Analytical Modeling ◽  
Variable Stiffness ◽  
Experimental Results ◽  
Analytic Model ◽  
Fabrication Method ◽  
Fem Simulations ◽  
Industrial Environments ◽  
The Stability ◽  
Stiffness Loss

For soft grippers to be applied in atypical industrial environments, they must conform to an object’s exterior shape and momentarily change their stiffness. However, many of the existing grippers have limitations with respect to these functions: they grasp an object with only a single curvature and a fixed stiffness. Consequently, those constraints limit the stability of grasping and the applications. This paper introduces a new multicurvature, variable-stiffness soft gripper. Inspired by the human phalanx and combining the phalanx structure and particle jamming, this work guarantees the required grasping functions. Unlike the existing soft pneumatic grippers with one curvature and one stiffness, this work tries to divide the pressurized actuating region into three parts to generate multiple curvatures for a gripper finger, enabling the gripper to increase its degrees of freedom. Furthermore, to prevent stiffness loss at an unpressurized segment, this work combines divided actuation and the variable-stiffness capability, which guarantee successful grasping actions. In summary, this gripper generates multiple grasping curvatures with the proper stiffness, enhancing its dexterity. This work introduces the new soft gripper’s design, analytical modeling, and fabrication method and verifies the analytic model by comparing it with FEM simulations and experimental results.

Analytical Modeling of Chatter Stability in Turning and Boring Operations—Part I: Model Development

2007 ◽  
Vol 129 (4) ◽  
pp. 726-732 ◽  
Author(s):  
Emre Ozlu ◽  
Erhan Budak
Keyword(s):  
Model Development ◽  
Three Dimensional ◽  
Chip Thickness ◽  
Stability Limit ◽  
Chatter Stability ◽  
Nose Radius ◽  
Process Dynamics ◽  
Model Predictions ◽  
Accurate Treatment ◽  
Acceptable Agreement

In this paper an analytical model for stability limit predictions in turning and boring operations is proposed. The multidimensional model includes the three-dimensional geometry of the processes resulting in an eigenvalue problem. In addition, a model for the chip thickness at the insert nose is proposed to observe the effect of the insert nose radius on the chatter stability limit. The model represents a development over existing ones due to accurate treatment of the multidimensional process dynamics and geometry, and resulting practical formulas for stability limit predictions. Chatter experiments are conducted for both turning and boring in order to verify the model predictions, and overall, an acceptable agreement is observed.

Optimization of the Robust Stability Limit for Multi-Cutter Turning Processes

2015 ◽  
Author(s):  
Marta J. Reith ◽  
Daniel Bachrathy ◽  
Gabor Stepan
Keyword(s):  
Robust Stability ◽  
Optimal Parameter ◽  
Stability Limit ◽  
Boundary Function ◽  
Lower Envelope ◽  
Computation Method ◽  
Parameter Region ◽  
Dynamical Parameters ◽  
The Stability ◽  
Machining Parameter

Multi-cutter turning systems bear huge potential in increasing cutting performance. In this study we show that the stable parameter region can be extended by the optimal tuning of system parameters. The optimal parameter regions can be identified by means of stability charts. Since the stability boundaries are highly sensitive to the dynamical parameters of the machine tool, the reliable exploitation of the so-called stability pockets is limited. Still, the lower envelope of the stability lobes is an appropriate upper boundary function for optimization purposes with an objective function taken for maximal material removal rates. This lower envelope is computed by the Robust Stability Computation method presented in the paper. It is shown in this study, that according to theoretical results obtained for optimally tuned cutters, the safe stable machining parameter region can significantly be extended, which has also been validated by machining tests.

Some difficulties associated with the limit equilibrium method of slices

1983 ◽  
Vol 20 (4) ◽  
pp. 661-672 ◽  
Author(s):  
R. K. H. Ching ◽  
D. G. Fredlund
Keyword(s):  
Slope Stability ◽  
Factor Of Safety ◽  
Limit Equilibrium ◽  
Stability Limit ◽  
Limit Equilibrium Method ◽  
Soil Conditions ◽  
Side Force ◽  
Limit Equilibrium Methods ◽  
Equilibrium Method ◽  
The Stability

Several commonly encountered problems associated with the limit equilibrium methods of slices are discussed. These problems are primarily related to the assumptions used to render the inherently indeterminate analysis determinate. When these problems occur in the stability computations, unreasonable solutions are often obtained. It appears that problems occur mainly in situations where the assumption to render the analysis determinate seriously departs from realistic soil conditions. These problems should not, in general, discourage the use of the method of slices. Example problems are presented to illustrate these difficulties and suggestions are proposed to resolve these problems. Keywords: slope stability, limit equilibrium, method of slices, factor of safety, side force function.

A Dynamical Model for Studying the Stability of Thermo-Solutal Convection Under the Effect of Vertical Vibration

2005 ◽  
Author(s):  
Y. P. Razi ◽  
M. Mojtabi ◽  
K. Maliwan ◽  
M. C. Charrier-Mojtabi ◽  
A. Mojtabi
Keyword(s):  
Stability Analysis ◽  
Mechanical Vibration ◽  
Stability Limit ◽  
Lewis Number ◽  
Vertical Vibration ◽  
Wave Number ◽  
Dimensionless Wave Number ◽  
Non Linear ◽  
Linear Differential ◽  
The Stability

This paper concerns the thermal stability analysis of porous layer saturated by a binary fluid under the influence of mechanical vibration. The linear stability analysis of this thermal system leads us to study the following damped coupled Mathieu equations: BH¨+B(π2+k2)+1H˙+(π2+k2)−k2k2+π2RaT(1+Rsinω*t*)H=k2k2+π2(NRaT)(1+Rsinω*t*)Fε*BF¨+Bπ2+k2Le+ε*F˙+π2+k2Le−k2k2+π2NRaT(1+Rsinω*t*)F=k2k2+π2RaT(1+Rsinω*t*)H where RaT is thermal Rayleigh number, R is acceleration ratio (bω2/g), Le is the Lewis number, k is the dimensionless wave-number, ε* is normalized porosity and N is the buoyancy ratio (H and F are perturbations of temperature and concentration fields). In the follow up, the non-linear behavior of the problem is studied via a generalization of the Lorenz model (five coupled non-linear differential equations with periodic coefficients). In the presence or absence of gravity, the stability limit for the onset of stationary as well as Hopf bifurcations is determined.

scholarly journals STABILITY OF HIGH DENSITY CUBES IN RUBBLE MOUND BREAKWATERS

2020 ◽  
pp. 4
Author(s):  
Yalcin Yuksel ◽  
Marcel van Gent ◽  
Esin Cevik ◽  
H. Alper Kaya ◽  
Irem Gumuscu ◽  
...  
Keyword(s):  
Relative Density ◽  
Slope Angle ◽  
High Density ◽  
Experimental Results ◽  
Normal Density ◽  
Stability Number ◽  
Damage Initiation ◽  
Rubble Mound ◽  
The Stability ◽  
Rubble Mound Breakwaters

The stability number for rubble mound breakwaters is a function of several parameters and depends on unit shape, placing method, slope angle, relative density, etc. In this study two different densities for cubes in breakwater armour layers were tested to determine the influence of the density on the stability. The experimental results show that the stability of high density blocks were found to be more stable and the damage initiation for high density blocks started at higher stability numbers compared to normal density cubes.

Stability of As and B doped Si with respect to overlaying CoSi2 and TiSi2 thin films

1989 ◽  
Vol 4 (5) ◽  
pp. 1209-1217 ◽  
Author(s):  
K. Maex ◽  
G. Ghosh ◽  
L. Delaey ◽  
V. Probst ◽  
P. Lippens ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Phase Diagrams ◽  
Thermodynamic Data ◽  
Ternary Phase ◽  
Experimental Results ◽  
Silicide Formation ◽  
Isothermal Sections ◽  
Ternary Phase Diagrams ◽  
The Stability

The thermodynamic equilibrium of structures consisting of a thin film silicide (TiSi2 or CoSi2) on doped Si (with As or B) is investigated. Isothermal sections of the ternary phase diagrams for Ti–Si–B, Co–Si–B, Ti–Si–As, and Co–Si–As have been evaluated, indicating the stability of high B concentrations in Si underneath a CoSi2 layer, the instability of high As concentrations in Si underneath a CoSi2 layer, and of B and As concentrations underneath a TiSi2 layer. The obtained thermodynamic predictions agree very well with experimental results (i) on the redistribution of dopants during silicide formation, (ii) on the diffusion of dopants from an ion implanted silicide, and (iii) on the stability of highly doped regions underneath the silicide, both for the case of TiSi2 and CoSi2. It is shown that even though the inaccuracy of reported thermodynamic data is substantial, thermodynamic calculations provide a useful guidance and are consistent with the experimental results.

Sign in / Sign up

Export Citation Format

Share Document