Instabilities Arising From the Frictional Interaction of a Pin-Disk System Resulting in Noise Generation

1976 ◽  
Vol 98 (1) ◽  
pp. 81-86 ◽  
Author(s):  
S. W. E. Earles ◽  
C. K. Lee
Keyword(s):  
Angular Speed ◽  
Degree Of Freedom ◽  
Noise Generation ◽  
Disk System ◽  
Single Degree Of Freedom ◽  
Disk Brake ◽  
Thin Steel ◽  
Three Degree Of Freedom ◽  
Squeal Noise ◽  
Experimental Rig

A steel pin, supported on a flexible cantilever, is pressed against a thin steel disk which rotates at a uniform angular speed. The orientation of the pin’s central axis to the plane of the disk, the bending and torsional stiffnesses of the pin support, the stiffness of the disk, and the line of action of the resultant interactive force are all shown to affect the self-induced coupled frequencies and modes generated. The analysis of the experimental arrangement in terms of a three-degree-of-freedom pin subsystem and a single-degree-of-freedom disk element suggests that the system is unstable for certain combinations of the variables. The instabilities are shown to belong to a class of “geometrically induced” or “kinematic constraint” instability. The region of squeal-noise generation within the experimental rig is shown to correspond to the oscillatory unstable region predicted theoretically. The noise generated is similar to disk-brake squeal, and so the work furthers the understanding of this practical problem.

Design and Modeling of a Three-Degree-of-Freedom Articulating Robotic Microsurgical Forceps for Trans-Oral Laser Microsurgery

2019 ◽  
Vol 13 (2) ◽  
Author(s):  
Manish Chauhan ◽  
Nikhil Deshpande ◽  
Darwin G. Caldwell ◽  
Leonardo S. Mattos
Keyword(s):  
Degree Of Freedom ◽  
Preliminary Evaluation ◽  
Laser Microsurgery ◽  
Single Degree Of Freedom ◽  
Control Interface ◽  
Tissue Manipulation ◽  
Manual Handling ◽  
Three Degree Of Freedom ◽  
Tool Rotation ◽  
Poor Efficacy

Trans-oral laser microsurgery (TLM) is a surgical procedure for removing malignancies (e.g., cysts, polyps, tumors) of the laryngeal region through laser ablation. Intraoperative microsurgical forceps (i.e., microforceps) are used for tissue manipulation. The microforceps are rigid, single degree-of-freedom (DOF) devices (open–close) with precurved jaws to access different parts of the curved cylindrical laryngeal region. These microforceps are manually handled and are subject to hand tremors, poor reachability, and nonergonomic use, resulting in poor efficacy and efficiency in the surgery. A novel 3DOF motorized microforceps device is presented here, integrated with a 6DOF serial robotic manipulator. The device, referred to as RMF-3, offers three motorized DOFs: (i) open–close forceps jaw; (ii) tool rotation; and (iii) tool-tip articulation. It is designed to be compliant with TLM spatial constraints. The manual handling is replaced by tele-operation device, the omega.7. The design of the RMF-3 is characterized through theoretical and experimental analysis. The device shows a maximum articulation of 38 deg and tool rotation of 100 deg. Its performance is further evaluated through user trials using the ring-in-loop setup. The user trials demonstrate benefits of the 3DOF workspace of the device along with its teleoperation control. RMF-3 offers an improved workspace and reachability within the laryngeal region. Surgeons, in their preliminary evaluation of the device, appreciated the ability to articulate the tip, along with rotation, for hard-to-reach parts of the surgical site. RMF-3 offers an ergonomic robotic teleoperation control interface which overcomes hand tremors and extreme wrist excursion which leads to surgeon pain and discomfort.

scholarly journals Modeling of Squeal Noise Generation in Disk Brake

2003 ◽  
Vol 2003.78 (0) ◽  
pp. _11-49_-_11-50_
Author(s):  
Tsutomu TAMURA ◽  
Yutaka KURITA ◽  
Yuichi MATSUMURA ◽  
Yasunori OOURA
Keyword(s):  
Noise Generation ◽  
Disk Brake ◽  
Squeal Noise

Resonant Dynamics and Saturation in a Coupled System With Quadratic Nonlinearities

2004 ◽  
Author(s):  
Reddy Mankala ◽  
D. Dane Quinn
Keyword(s):  
Angular Velocity ◽  
Normal Modes ◽  
Coupled System ◽  
Angular Speed ◽  
Degree Of Freedom ◽  
Weakly Coupled System ◽  
Quadratic Nonlinearities ◽  
Resonant Dynamics ◽  
Three Degree Of Freedom ◽  
Dynamic Resonance

This work examines the behavior of a three-degree-of-freedom weakly coupled system. The system is composed of two components. The first is a two degree-of-freedom translational system that possesses an internal 2 : 1 resonance between the linear normal modes, which are coupled through quadratic nonlinearities. Under external forcing this component exhibits the saturation phenomena. The second is a rotational mass with a small imbalance, supported by the translational component. The angular speed of the rotor is not fixed, rather, the rotor is subject to a small torque and therefore its angular velocity slowly varies in time. A dynamic resonance occurs when the angular velocity of the rotor evolves to a neighborhood of one of the frequencies of the linear normal modes. Each of these resonances has been independently investigated previously in the literature. This work uncovers how the behavior of the dynamic resonance is modified by the mode coupling introduced by the 2 : 1 internal resonance and describes how the amplitudes of the linear normal modes are dependent on the properties of the dynamic resonance.

On the Critical Speed of Continuous Shaft-Disk Systems

1984 ◽  
Vol 106 (1) ◽  
pp. 59-61 ◽  
Author(s):  
H. Nevzat O¨zgu¨ven
Keyword(s):  
Critical Speed ◽  
Degree Of Freedom ◽  
Mass Ratio ◽  
Disk System ◽  
Single Degree Of Freedom ◽  
Single Degree

The critical speed of a shaft-disk system can be approximately determined from a single degree-of-freedom model. The errors in the critical speed predictions obtained from such a model are investigated. The percentage errors are plotted against disk to shaft mass ratio for different bearings and various disk locations.

Energy Transfer and Dissipation in a Three-Degree-of-Freedom System With Stribeck Friction

2005 ◽  
Author(s):  
Nguyen Do ◽  
Aldo A. Ferri
Keyword(s):  
Energy Transfer ◽  
Low Frequency ◽  
Friction Model ◽  
Degree Of Freedom ◽  
Simulation Studies ◽  
Transfer Energy ◽  
Interconnected System ◽  
Single Degree Of Freedom ◽  
Low Frequency Motion ◽  
Three Degree Of Freedom

Friction at connecting joints is a key mechanism by which passive damping occurs in built-up structures. This paper explores the ability of friction to transfer energy between subsystems of an interconnected system. Two single-degree-of-freedom (SDOF) systems are used to represent separate subsystems and a third mass is used to represent the connecting joint. A Stribeck friction model is used to represent the resistive force acting on this coupling mass. Through numerical simulation studies, the influence of the subsystem dynamics on the overall energy dissipation levels is investigated. In particular, it is seen that favorable tuning conditions exist that result in a “pumping” of energy from the low-frequency motion of one subsystem to the higher-frequency motion of the other subsystem. It is also seen that one-way energy transfer can occur in such a system due to the eventual joint lock-up that can occur when the connecting mass sticks.

scholarly journals Inelastic Responses of Two-Way Asymmetric-Plan Structures under Bidirectional Ground Excitations—Part II: Response Spectra

2012 ◽  
Vol 28 (1) ◽  
pp. 141-157 ◽  
Author(s):  
Jui-Liang Lin ◽  
Wen-Chia Yang ◽  
Keh-Chyuan Tsai
Keyword(s):  
Vibration Mode ◽  
Response Spectra ◽  
Companion Paper ◽  
Degree Of Freedom ◽  
Single Degree Of Freedom ◽  
Ductility Demand ◽  
Inelastic Responses ◽  
Constant Strength ◽  
Three Degree Of Freedom ◽  
Modal Systems

Based on the studies in the companion paper, this paper presents the inelastic response spectra for asymmetrical structures (SAS) under bidirectional ground excitations. Firstly, the constant-strength SAS were constructed and compared with the corresponding conventional constant-strength response spectra. It was found that the modal ductility demands of an asymmetric-plan structure could be significantly overestimated from the conventional constant-strength response spectra as the nonlinear “modal” rotation and translations may not be proportional. Furthermore, the translation-rotation interaction effect is not considered in the conventional constant-strength response spectra. Secondly, the influences of the three-degree-of-freedom (3DOF) modal parameters on the ductility demand were extensively studied. Thirdly, the normalized peak edge translation spectra were also investigated. It was found that the normalized peak edge translation resulting from a single vibration mode may be overestimated twofold by using the single-degree-of-freedom (SDOF) modal systems.

Brake Squeal Noise Due to Disk Misalignment

2005 ◽  
Author(s):  
Yeon-Sun Choi ◽  
Ju-Pyo Park
Keyword(s):  
Stability Analysis ◽  
Degree Of Freedom ◽  
Experimental Results ◽  
Brake System ◽  
Nonlinear Friction ◽  
Brake Squeal ◽  
Friction Characteristic ◽  
Brake Dynamometer ◽  
Three Degree Of Freedom ◽  
Squeal Noise

To understand brake squeal noise, the sound and vibration of an automobile brake system were measured using a brake dynamometer. The experimental results show that an important factor in squeal generation is the run-out due to disk misalignment. A three-degree of freedom model is developed for the brake system, where the run-out effect and nonlinear friction characteristic are included. A stability analysis of the model was also performed to predict the generation of squeal with the modification of the brake system. The results show that squeal generation is dependant on the run-out rather than the friction characteristic between pad and disk.

scholarly journals Passive Shock Isolation Utilising Dry Friction

2017 ◽  
Vol 2017 ◽  
pp. 1-21 ◽  
Author(s):  
Mohd Ikmal Ismail ◽  
Neil Stuart Ferguson
Keyword(s):  
Degree Of Freedom ◽  
Experimental Results ◽  
Maximum Displacement ◽  
Natural Period ◽  
Single Degree Of Freedom ◽  
Excited System ◽  
Theoretical Predictions ◽  
Shock Isolation ◽  
Two Degree Of Freedom ◽  
Experimental Rig

A novel shock isolation strategy for base excited system is presented by introducing a two-degree-of-freedom model with passive friction, where the friction is applied to an attached mass instead of directly to the primary isolated mass. The model is evaluated against the benchmark case of single-degree-of-freedom system with friction applied directly to the primary isolated mass. The performances of the models are compared in terms of the maximum displacement response and the acceleration during the application of the shock input for the case when the shock input duration is approximately equal to the natural period of the system (amplification region). From the results, the two-degree-of-freedom model can produce both maximum displacement reduction and smoother acceleration at the point of motion transition. An experimental rig was built to validate the theoretical results against the experimental results; it is found that the experimental results closely match the theoretical predictions.

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