Modeling and Experimental Methods for Dynamic Analysis of the Spaghetti Problem

2005 ◽  
Vol 127 (1) ◽  
pp. 44-51 ◽  
Author(s):  
Hiroyuki Sugiyama ◽  
Nobuyuki Kobayashi ◽  
Yoshimasa Komaki
Keyword(s):  
High Speed ◽  
Industrial Applications ◽  
Modeling Method ◽  
Contact Forces ◽  
Flexible Body ◽  
Flexible Beam ◽  
Experimental Procedure ◽  
Large Rotation ◽  
Finite Segment Method ◽  
Material Length

The nonlinear dynamics of a very flexible body with time-variant length encompasses several industrial applications such as high-speed automatic coiling machines and copy machines. Among others, the significant increase in the vibration that occurs when the material length is shortened with time is known as the spaghetti problem. In this paper, the modeling method and the experimental procedure for the analysis of the spaghetti problem are presented. The change in the state of the forces and displacements at the boundary with a clearance is taken into consideration by modeling the mechanical interactions resulting from the clearance. A flexible beam is modeled using the finite segment method to account for the geometric nonlinearities due to the large rotation. The contact forces at the boundary are modeled using a set of springs and dampers. The numerical results obtained using the proposed modeling method agree well with the results obtained using the experiment. The effect of the transport velocity and the clearance are demonstrated, and the cause of the significant increase in the flexible body vibration is discussed from an energy balance viewpoint.

Stability of Transported Flexible Beam With Elastic Support

2005 ◽  
Author(s):  
Ken-Ichiro Aida ◽  
Nobuyuki Kobayashi ◽  
Yajun Zhang ◽  
Hiroyuki Sugiyama
Keyword(s):  
Elastic Support ◽  
Damping Coefficient ◽  
Flexible Beam ◽  
Beam Model ◽  
Finite Segment ◽  
Large Rotation ◽  
Finite Segment Method ◽  
Negative Damping ◽  
The Stability ◽  
Variant System

The stability of translating flexible beam that passes through the elastic support is investigated. We modeled the flexible beam using the finite segment method to account for the geometric nonlinearities due to the large rotation, as it is the time variant system. Numerical simulation results show the instability of the beam, that is stable in the low axial moving velocity, is observed as the axial moving velocity increases. It is clarified from the consideration with the simplified rigid beam model that the mass and damping coefficient ratio of the elastic support yields negative damping effect of the system and the damping coefficient and stiffness ratio of the elastic support yields negative stiffness effect of the system as the axial moving velocity increases. These results show that the property of the elastic support gives the significant effect on the instability of the translating beam.

Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

A Nonlinear Rail Vehicle Dynamics Computer Program SAMS/Rail: Part 1—Theory and Formulations

2009 ◽  
Author(s):  
Khaled E. Zaazaa ◽  
Brian Whitten ◽  
Brian Marquis ◽  
Erik Curtis ◽  
Magdy El-Sibaie ◽  
...  
Keyword(s):  
High Speed ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Contact Element ◽  
Contact Forces ◽  
Simulation Code ◽  
Vehicle Performance ◽  
Normal Contact ◽  
Advantages And Disadvantages ◽  
High Speed Trains

Accurate prediction of railroad vehicle performance requires detailed formulations of wheel-rail contact models. In the past, most dynamic simulation tools used an offline wheel-rail contact element based on look-up tables that are used by the main simulation solver. Nowadays, the use of an online nonlinear three-dimensional wheel-rail contact element is necessary in order to accurately predict the dynamic performance of high speed trains. Recently, the Federal Railroad Administration, Office of Research and Development has sponsored a project to develop a general multibody simulation code that uses an online nonlinear three-dimensional wheel-rail contact element to predict the contact forces between wheel and rail. In this paper, several nonlinear wheel-rail contact formulations are presented, each using the online three-dimensional approach. The methods presented are divided into two contact approaches. In the first Constraint Approach, the wheel is assumed to remain in contact with the rail. In this approach, the normal contact forces are determined by using the technique of Lagrange multipliers. In the second Elastic Approach, wheel/rail separation and penetration are allowed, and the normal contact forces are determined by using Hertz’s Theory. The advantages and disadvantages of each method are presented in this paper. In addition, this paper discusses future developments and improvements for the multibody system code. Some of these improvements are currently being implemented by the University of Illinois at Chicago (UIC). In the accompanying “Part 2” and “Part 3” to this paper, numerical examples are presented in order to demonstrate the results obtained from this research.

Development of an End-Effector for Mitigation of Collisions

2021 ◽  
Author(s):  
Domenico Tommasino ◽  
Matteo Bottin ◽  
Giulio Cipriani ◽  
Alberto Doria ◽  
Giulio Rosati
Keyword(s):  
Numerical Simulations ◽  
Industrial Applications ◽  
Operating Conditions ◽  
Contact Forces ◽  
Design Parameters ◽  
End Effector ◽  
Linear Behavior ◽  
Stable Mechanism ◽  
Robot Tasks ◽  
The Impact

Abstract In robotics the risk of collisions is present both in industrial applications and in remote handling. If a collision occurs, the impact may damage both the robot and external equipment, which may result in successive imprecise robot tasks or line stops, reducing robot efficiency. As a result, appropriate collision avoidance algorithms should be used or, if it is not possible, the robot must be able to react to impacts reducing the contact forces. For this purpose, this paper focuses on the development of a special end-effector that can withstand impacts and is able to protect the robot from impulsive forces. The novel end-effector is based on a bi-stable mechanism that decouples the dynamics of the end-effector from the dynamics of the robot. The intrinsically non-linear behavior of the end-effector is investigated with the aid of numerical simulations. The effect of design parameters and the operating conditions are analyzed and the interaction between the functioning of the bi-stable mechanism and the control system is studied. In particular, the effect of the mechanism in different scenarios characterized by different robot velocities is shown. Results of numerical simulations assess the validity of the proposed end-effector, which can lead to large reductions in impact forces.

Three Practical Examples of Magnetic Bearing Control Design Using a Modern Tool

2002 ◽  
Vol 124 (4) ◽  
pp. 1025-1031 ◽  
Author(s):  
M. Spirig ◽  
J. Schmied ◽  
P. Jenckel ◽  
U. Kanne
Keyword(s):  
Dynamic Behavior ◽  
High Speed ◽  
Control Design ◽  
Industrial Applications ◽  
Magnetic Bearing ◽  
Engineering Practice ◽  
Digital Implementation ◽  
Bearing Characteristic ◽  
Multistage Centrifugal Compressor ◽  
Modern Tool

The use of magnetic bearing in industrial applications has increased due to their unique properties. Nowadays efficiency and predictability in handling rotors on magnetic bearings is asked with the same standard as conventional rotors on oil or roller bearings. First of all one must be aware of the special technical properties of magnetic bearing designs. The dynamic behavior of the rotor combined with requirements of the application define the desired bearing characteristic. With modern tools covering the mechanical aspects as well as the electronic controllers and their digital implementation on a DSP, these properties can be designed. However, despite the use of such efficient tools engineering practice is needed. Therefore this paper summarizes the major steps in the control design process of industrial applications. Three rotors supported on magnetic bearing with their specific dynamic behavior are presented: a very small high speed spindle (120,000 rpm); a small industrial turbo molecular pump rotor (36,000 rpm); and a large multistage centrifugal compressor (600 to 6300 rmp). The results of the analyses and their experimental verification are given.

scholarly journals On multi-sensor monitoring of fiber laser fusion cutting

2021 ◽  
Vol 1135 (1) ◽  
pp. 012014
Author(s):  
Nikita Levichev ◽  
Joost R. Duflou
Keyword(s):  
Fiber Laser ◽  
Monitoring System ◽  
Laser Cutting ◽  
High Speed ◽  
Process Zone ◽  
Industrial Process ◽  
Industrial Applications ◽  
Laser Fusion ◽  
Thick Plates ◽  
Sensor Monitoring

Abstract Laser cutting is a well-established industrial process for sheet metal applications. However, cutting thick plates is still accompanied by problems because of the characteristic limited process parameter window. Since cutting by means of fiber lasers has become dominant, tailored solutions are required in such systems for industrial applications. The development of a robust real-time monitoring system, which adapts the process parameters according to a specific quality requirement, implies a significant step forward towards automated laser cutting and increases the process robustness and performance. In this work, a coaxial multi-sensor monitoring system is tested for fiber laser cutting of stainless steel thick plates. A high-speed camera and a photodiode sensor have been selected for this investigation. Experiments at different cutting speeds, representing primary cut quality cases, have been conducted and various features of the obtained process zone signals have been examined. Finally, the feasibility of industrial application of the developed setup for high-power fiber laser cutting is discussed, followed by several implementation recommendations.

A modeling method of algorithm-hardware based on SysML

2021 ◽  
Author(s):  
Liu Yue ◽  
Zhao Chun ◽  
Zhang Lin
Keyword(s):  
Graphical Models ◽  
Integrated Circuit ◽  
High Speed ◽  
System Modeling ◽  
Modeling Method ◽  
Description Language ◽  
Hardware Description ◽  
Circuit And System ◽  
Graphical System ◽  
Hardware Circuit

In the process of complex product design, modeling in different fields and different disciplines is often involved. Designers often face many different development kits, platforms, and theories, among which significant differences exist. Especially in the process of algorithm-hardware implementation, it is necessary to have mastery of the knowledge including algorithm, hardware, circuit, and system engineering. In this paper, a modeling method of algorithm-hardware based on SysML is proposed to reduce the difficulty of algorithm-hardware modeling. By using the method, the designers who do not know the knowledge of hardware can also easily build the algorithm-hardware model. In this method, a method of graphical system modeling based on SysML is used, where the elements of the algorithm-hardware model are described by SysML graphical models. Then, the SysML graphical models are converted to Very-High-Speed Integrated Circuit Hardware Description Language. At last, a detecting algorithm of random number is complemented by the modeling method in this paper and the simulation results are presented at the conclusion.

Theory and Measurements of the Propeller-Induced Vibratory Pressure Field

1972 ◽  
Vol 16 (02) ◽  
pp. 124-139
Author(s):  
W. R. Jacobs ◽  
J. Mercier ◽  
S. Tsakonas
Keyword(s):  
High Speed ◽  
Pressure Field ◽  
Processing Technique ◽  
Experimental Program ◽  
Signal Processing Technique ◽  
Experimental Procedure ◽  
Surface Theory ◽  
Blade Frequency ◽  
Development Center ◽  
Theoretical Results

A theory has been developed, based on lifting surface theory, for evaluation of the pressure field generated by an operating propeller in a nonuniform inflow field. In addition, an experimental procedure and a signal processing technique for measuring small pressure levels accurately have been established and utilized in an extensive experimental program. Theoretical results obtained by means of a computer program developed for the CDC 6600 high-speed digital computer agree well with those of experiments conducted at Davidson Laboratory and at the Naval Ship Research and Development Center. The difficulty of accurately establishing by measurements the decay of small pressures at points farther than one radius from the propeller precludes the possibility of determining the blade-frequency force exerted on a flat boundary by integrating the measured signatures. In contrast, integration of double the theoretical free-space pressure over the flat boundary appears to be a feasible and meaningful approach.

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