scholarly journals Design of Chatter-Resistant Damped Boring Bars Using a Receptance Coupling Approach

2020 ◽  
Vol 4 (2) ◽  
pp. 53 ◽  
Author(s):  
Ajay Yadav ◽  
Devangkumar Talaviya ◽  
Ankit Bansal ◽  
Mohit Law
Keyword(s):  
Stability Limit ◽  
Analytical Models ◽  
Classical Solutions ◽  
System Response ◽  
Chatter Vibration ◽  
Boring Bar ◽  
Damped System ◽  
Receptance Coupling ◽  
Coupling Approach ◽  
Stiffness And Damping

Deep hole boring using slender bars that have tuned mass dampers integrated within them make the boring process chatter vibration resistant. Dampers are usually designed using classical analytical solutions that presume the (un)damped boring bar which can be approximated by a single degree of freedom system, and the damper is placed at the free end. Since the free end is also the cutting end, analytical models may result in infeasible design solutions. To place optimally tuned dampers within boring bars, but away from the free end, this paper presents a receptance coupling approach in which the substructural receptances of the boring bar modelled as a cantilevered Euler–Bernoulli beam are combined with the substructural receptances of a damper modelled as a rigid mass integrated anywhere within the bar. The assembled and damped system response thus obtained is used to predict the chatter-free machining stability limit. Maximization of this limit is treated as the objective function to find the optimal mass, stiffness and damping of the absorber. Proposed solutions are first verified against other classical solutions for assumed placement of the absorber at the free end. Verified models then guide prototyping of a boring bar integrated with a damper placed away from its free end. Experiments demonstrate a ~100-fold improvement in chatter vibration free machining capability. The generalized methods presented herein can be easily extended to design and develop other damped and chatter-resistant tooling systems.

Identification of Dynamical Contact Parameters for Spindle-Tool Holder Interface Based on the Receptance Coupling Substructure Approach

2011 ◽  
Vol 287-290 ◽  
pp. 2185-2190
Author(s):  
Yong Sheng Zhao ◽  
Ri Qing Dong ◽  
Zhi Feng Liu ◽  
Tie Neng Guo
Keyword(s):  
Contact Dynamics ◽  
Chatter Stability ◽  
Simple Manner ◽  
Accurate Identification ◽  
Tool Holder ◽  
Receptance Coupling ◽  
Dynamical Parameters ◽  
Substructure Approach ◽  
Stiffness And Damping ◽  
Contact Parameters

It is very crucial to accurately identify the parameters of contact dynamics in predicting the chatter stability of spindle–tool holder assemblies in machining centers. Fast and accurate identification of contact dynamics in spindle–tool holder assembly has become an important issue in the recent years. In this paper, the receptance coupling substructure approach is employed for identification the stiffness and damping of the interface in a simple manner, in which the frequency response function of the tool holder is derived from the Timoshenko beam finite elements model. A BT 50 type tool holder is adopted as an application example of the method. Although this study focuses on the contact dynamics at the spindle–tool holder interfaces of the assembly, the approach might be used for identifying the dynamical parameters of other critical interface.

Using noise control principles when evaluating the acoustic impacts of face coverings during the coronavirus pandemic

2021 ◽  
Vol 263 (3) ◽  
pp. 3554-3561
Author(s):  
Richard Ruhala ◽  
Laura Ruhala
Keyword(s):  
Classroom Environment ◽  
Noise Control ◽  
Experimental Tests ◽  
Analytical Models ◽  
Octave Band ◽  
Interference Level ◽  
Cavity Resonances ◽  
The Face ◽  
Clear Plastic ◽  
Stiffness And Damping

Several different combinations of face masks and shields are evaluated for their acoustic performance using a head and torso simulator (HATS). The HATS is used as a controlled and repeatable artificial sound source using white noise in a classroom environment. Sound pressure levels at octave band frequencies due to the face coverings are evaluated at a location of 2.0 meters from the HATS which is within the direct field to reduce the room acoustical effects. The problem is modeled as a barrier separating a source and receiver using fundamental noise control principles. Fabric material properties are used such as thickness, density, stiffness, and damping. The results are compared with experimental tests. The face shield with clear plastic barrier produces a resonance in the 1000 Hz octave band. Analytical models of cavity resonances, standing wave resonances, or plate resonances are calculated and compared with the experimental resonance. The speech interference level is used to determine the frequency content that is most likely to cause hearing difficulties and compared with A-weighted differences between the unmasked condition and masked.

Stability Analysis of Chatter System on Ultrasonic Honing

2013 ◽  
Vol 712-715 ◽  
pp. 1241-1247
Author(s):  
Yun Peng Shao ◽  
Xi Jing Zhu ◽  
Meng Liu ◽  
Zhen Liu
Keyword(s):  
Combustion Engine ◽  
Damping Ratio ◽  
Stability Limit ◽  
Cylinder Liner ◽  
Spindle Speed ◽  
Machining System ◽  
Motion Speed ◽  
The Stability ◽  
Stiffness And Damping

The chatter caused by the inner factors of the machining system in the ultrasonic honing process would seriously affect the surface quality of combustion engine. A dynamical model of ultrasonic honing chatter system was established, which involved with ultrasonic honing mechanism and dynamic honing depth, the relationship between the limit honing width and honing speed was deduced based on the theory of regenerative chatter; the simulation was carried out to obtain the effect of different parameters including stiffness coefficient, damping ratio, spindle speed and reciprocation motion speed on the stability limit curve of the chatter system. It can be concluded that the ultrasonic honing chatter system have better stability with low spindle speed, high stiffness and damping ratio, which providing foundation to eliminate ultrasonic honing system chatter in the precision machining of cylinder liner.

A Study of Linear Joint and Tool Models in Spindle-Holder-Tool Receptance Coupling

2005 ◽  
Author(s):  
Timothy J. Burns ◽  
Tony L. Schmitz
Keyword(s):  
Frequency Response ◽  
High Speed ◽  
Nonlinear Least Squares ◽  
Analytical Models ◽  
Connection Matrix ◽  
Depth Of Cut ◽  
Combined System ◽  
Receptance Coupling ◽  
Overhang Length ◽  
Exponential Trend

The dynamics of a spindle-holder-tool (SHT) system during high-speed machining is sensitive to changes in tool overhang length. A well-known method for predicting the limiting depth of cut for avoidance of tool chatter requires a good estimate of the tool-point frequency response (FRF) of the combined system, which depends upon the tool length. In earlier work, a combined analytical and experimental method has been discussed, that uses receptance coupling substructure analysis (RCSA) for the rapid prediction of the combined spindle-holder-tool FRF. The basic idea of the method is to combine the measured direct displacement vs. force receptance (i.e., frequency response) at the free end of the spindle-holder (SH) system with calculated expressions for the tool receptances based on analytical models. The tool was modeled as an Euler-Bernoulli (EB) beam, the other three spindle-holder receptances were set equal to zero, and the model for the connection with the tool led to a diagonal matrix. The main conclusion of the earlier work was that there was an exponential trend in the dominant connection parameter, which enabled interpolation between tip receptance data for the longest and shortest tools in the combined SHT system. Thus, a considerable savings in time and effort could be realized for the particular SHT system. A question left open in the earlier work was: how general is this observed exponential trend? Here, to explore this question further, an analytical EB model is used for the SH system, so that all four of its end receptances are available, and the tool is again modeled as a free-free EB beam that is connected to the SH by a specified connection matrix, that includes nonzero off-diagonal terms. This serves as the “exact” solution. The approximate solution is once again formed by setting all but one SH receptance equal to zero, and the connection parameters are determined using nonlinear least squares software. Both diagonal and full connection matrices are investigated. The main result is that, for this system, in the case of a diagonal connecting matrix, there is no apparent trend in the dominant connecting spring stiffness with tool overhang length. However, in the full connecting matrix case, a general constant trend is observed, with some interesting exceptions.

Damped Transition of a Strongly Nonlinear System of Coupled Oscillators Into a State of Continuous Resonance Scattering

2011 ◽  
Author(s):  
David Andersen ◽  
Xingyuan Wang ◽  
Yuli Starosvetsky ◽  
Kevin Remick ◽  
Alexander Vakakis ◽  
...  
Keyword(s):  
Equations Of Motion ◽  
Resonance Scattering ◽  
Linear Oscillator ◽  
System Response ◽  
Analytical Treatment ◽  
Strongly Nonlinear ◽  
Damped System ◽  
Initial Excitation ◽  
Strongly Nonlinear System ◽  
Energy Plane

We examine analytically and experimentally a new phenomenon of ‘continuous resonance scattering’ in an impulsively excited, two-mass oscillating system. This system consists of a grounded damped linear oscillator with a light, strongly nonlinear attachment. Previous numerical simulations revealed that for certain levels of initial excitation, the system engages in a special type of response that appears to track a solution branch formed by the so-called ‘impulsive orbits’ of this system. By this term we denote the periodic (under conditions of resonance) or quasi-periodic (under conditions of non-resonance) responses of the system when a single impulse is applied to the linear oscillator with the system being initially at rest. By varying the magnitude of the impulse we obtain a manifold of impulsive orbits in the frequency-energy plane. It appears that the considered damped system is capable of entering into a state of continuous resonance scattering, whereby it tracks the impulsive orbit manifold with decreasing energy. Through analytical treatment of the equations of motion, a direct relationship is established between the frequency of the nonlinear attachment and the amplitude of the linear oscillator response, and a prediction of the system response during continuous scattering resonance is provided. Experimental results confirm the analytical predictions.

Dämpfungsmaße in Lagerpassungen*/Identification of damping values for spindle bearing interfaces

2019 ◽  
Vol 109 (05) ◽  
pp. 342-346
Author(s):  
C. Brecher ◽  
T. Motschke ◽  
M. Fey
Keyword(s):  
Dynamic Simulation ◽  
State Of The Art ◽  
Mechanical Systems ◽  
Journal Bearings ◽  
Hertzian Contact ◽  
Analytical Models ◽  
Ball Bearings ◽  
The Past ◽  
Spindle Bearing ◽  
Stiffness And Damping

Die präzise Simulation mechanischer Systeme erfordert neben Steifigkeitswerten für Koppelelemente, die Kenntnis von Dämpfungswerten. Im Gegenteil zu Gleitlagern sind die physikalischen Effekte in Wälzlagern, die zur Energiedissipation führen, nur mit sehr großem rechnerischen Aufwand numerisch beschreibbar und experimentell validierte Modelle besitzen nur in engen Betriebsgrenzen Gültigkeit. Als Hauptdämpfungsquellen wurden bisher Kugel-Laufbahn-Kontakte sowie die Passungen der Lagerringe identifiziert. Letztere werden in diesem Beitrag untersucht. Ziel ist eine Aussage über Grenzen, innerhalb derer sich der Einfluss von Fugendämpfung bewegt   The dynamic simulation of mechanical systems requires reliable stiffness and damping values to enable meaningful results. Especially the inclusion of coupling elements into the simulation always leads to challenges regarding the interpretation of predicted results. Unlike journal bearings, there are no analytical models for roller and ball bearings that allow the prediction of damping values, whereas the prediction of stiffness values is already state of the art. In the past, the Hertzian contact as well as the bearing interfaces were identified as the main damping sources, but till today, no reliable models have been derived. This article deals therefore with a method to quantify the influence of bearing interface damping parameters.

0602 Efficient receptance coupling approach for tool-tip dynamics identification

2015 ◽  
Vol 2015.8 (0) ◽  
pp. _0602-1_-_0602-6_
Author(s):  
Filippo MONTEVECCHI ◽  
Niccolo GROSSI ◽  
Antonio SCIPPA ◽  
Gianni CAMPATELLI
Keyword(s):  
Receptance Coupling ◽  
Coupling Approach ◽  
Dynamics Identification

Design of Anisotropic Boring Tools With L/D = 10 for Chatter Free Cutting

2017 ◽  
Author(s):  
Wataru Takahashi ◽  
Norikazu Suzuki ◽  
Eiji Shamoto
Keyword(s):  
Past Research ◽  
Depth Of Cut ◽  
Chatter Stability ◽  
Chatter Vibration ◽  
Element Analysis ◽  
Boring Bar ◽  
The Past ◽  
Cylinder Length ◽  
Low Stiffness ◽  
Stable Zone

This paper presents design of a novel boring bar with a ratio of cylinder length to diameter (L/D) of 10 to suppress chatter vibration regardless of low stiffness. It is essentially difficult to decrease the compliance of the long slender structures. However, nominal compliance of the displacement along the depth of cut direction against the resultant cutting force may be regulated by giving the designated anisotropy upon the boring bar dynamics. The past research has clarified the feasibility through turning experiments by using the developed boring bar with L/D of 4. In the present study, much slenderer ones with L/D of 10 are designed, which are significantly flexible but attractive to manufacturers. Finite element analysis (FEA) is utilized to estimate dynamics of the anisotropic boring bar. Through analytical investigations, two kinds of boring bars were designed, where the compliance ratio of 1.53 or 1.88 was accomplished. Influence of several conditions on the chatter stability was investigated. Analytical investigations revealed that the chatter stability is significantly improved at a designated depth of cut by utilizing the proposed designs regardless of feed rate. In particular, the compliance ratio of 1.55 showed wider stable zone to attain chatter free boring, while chatter avoidance is impossible by use of the conventional isotropic boring bar under the same conditions.

Influence of Geometric Design Parameters Onto Vibratory Response and HCF Safety for Turbine Blades With Friction Damper

2018 ◽  
Author(s):  
Matthias Hüls ◽  
Lars Panning-von Scheidt ◽  
Jörg Wallaschek
Keyword(s):  
Aspect Ratio ◽  
High Cycle Fatigue ◽  
Turbine Blades ◽  
Design Parameters ◽  
System Response ◽  
Blade Design ◽  
Cycle Fatigue ◽  
Resonance Amplitude ◽  
Damped System ◽  
Vibratory Response

Among the major concerns for high aspect-ratio turbine blades are forced and self-excited (flutter) vibrations which can cause failure by high-cycle fatigue. The introduction of friction damping in turbine blades, such as by coupling of adjacent blades via under platform dampers, can lead to a significant reduction of resonance amplitudes at critical operational conditions. In this paper, the influence of basic geometric blade design parameters onto the damped system response will be investigated to link design parameters with functional parameters like damper normal load, frequently used in nonlinear dynamic analysis. The shape of a simplified large aspect-ratio turbine blade is parameterized along with the under platform damper configuration. The airfoil is explicitly included into the parameterization in order to account for changes in blade mode shapes. For evaluation of the damped system response under a typical excitation, a reduced order model for non-linear friction damping is included into an automated 3D FEA tool-chain. Based on a design of experiments approach, the design space will be sampled and a surrogate model is trained on the received dataset. Subsequently, the mean and interaction effects of the true geometric blade design parameters onto the resonance amplitude and safety against high-cycle fatigue will be outlined for a critical first bending type vibrational motion. Design parameters were mainly found to influence the resonance amplitude by their effect onto the tip-to-platform deflection ratio. The HCF safety was affected by those design parameters with large sensitivity onto static and resonant vibratory stress levels. Applying an evolutionary optimization algorithm, it is shown that the optimum blade design with respect to minimum vibratory response at a particular node can differ significantly from a blade designed toward maximum HCF safety.

Sign in / Sign up

Export Citation Format

Share Document