An Experimental and Analytical Investigation of the Dynamic Response of a High-Speed Cam-Follower System. Part 2: A Combined, Lumped/Distributed Parameter Dynamic Model

1983 ◽  
Vol 105 (4) ◽  
pp. 699-704 ◽  
Author(s):  
A. P. Pisano ◽  
F. Freudenstein
Keyword(s):  
Dynamic Response ◽  
Dynamic Model ◽  
High Speed ◽  
Analytical Investigation ◽  
System Response ◽  
Distributed Parameter ◽  
Normal System ◽  
Cam Follower ◽  
Return Spring ◽  
Pathological Behavior

Part 2 describes the development of a dynamic model of a high-speed cam-follower system in which the return spring is modeled as a distributed-parameter element. The dynamic response requires the solution of a coupled set of differential equations, one ordinary and one partial. The dynamic model has the unique capability of faithfully reproducing the effect of the higher harmonics of the cam lift curve on system performance. The model, which has been refined and verified with the aid of the results described in Part 1, is capable of accurately predicting both normal system response as well as pathological behavior associated with the onset of toss, bounce, and spring surge. In comparison, a lumped-parameter dynamic model (differing only in the modeling of the valve spring) does not adequately predict the onset of pathological behavior.

An Experimental and Analytical Investigation of the Dynamic Response of a High-Speed Cam-Follower System. Part 1: Experimental Investigation

1983 ◽  
Vol 105 (4) ◽  
pp. 692-698 ◽  
Author(s):  
A. P. Pisano ◽  
F. Freudenstein
Keyword(s):  
Dynamic Response ◽  
High Speed ◽  
Dynamic Models ◽  
Analytical Investigation ◽  
System Response ◽  
Pathological System ◽  
Cam Design ◽  
Cam Follower ◽  
System Part ◽  
Basic Experiments

This paper is concerned with filling two gaps in the cam design field: (a) the absence of adequate measurements of the dynamic response of cam-follower systems, and (b) the need for the development of a predictive dynamic model for both normal and pathological system behavior. Part 1 presents the results of basic experiments on the dynamic response of a modern, high-speed cam-follower system. These data, which we believe to be the most comprehensive available in the open literature, and which are described more fully in [11], can be used by research investigators both in understanding system response and in developing and evaluating predictive dynamic models.

Analytical Dynamic Response of Elastic Cam-Follower Systems with Distributed Parameter Return Spring

1993 ◽  
Vol 115 (3) ◽  
pp. 612-620 ◽  
Author(s):  
Y. Samim U¨nlu¨soy ◽  
S. Turgut Tu¨mer
Keyword(s):  
Dynamic Response ◽  
High Speed ◽  
Systems Approach ◽  
Distributed Parameter ◽  
Lumped Model ◽  
Distributed Parameter Model ◽  
Pole Parameter ◽  
Cam Follower ◽  
Method Of Solution ◽  
Return Spring

An analytical method of solution for the high-speed dynamic response of a lumped/distributed parameter model for cam-follower systems is developed. The model combines the distributed parameter model of the return spring with a viscously damped, single degree-of-freedom, lumped model of the elastic follower train. The cam event is considered as a periodic motion, of period 360 deg, and is represented by its Fourier series approximation. Linear systems approach utilizing four-pole parameter representation of lumped and distributed elements is adopted. The applicability and the accuracy of the method are verified with the aid of the experimental results reported in recent literature on the dynamic response of a high-speed cam-follower system.

The Development of a Predictive Model for the Optimization of High-Speed Cam-Follower Systems with Coulomb Damping Internal Friction and Elastic and Fluidic Elements

1986 ◽  
Vol 108 (4) ◽  
pp. 506-515 ◽  
Author(s):  
Shervin Hanachi ◽  
Ferdinand Freudenstein
Keyword(s):  
Energy Dissipation ◽  
Dynamic Model ◽  
High Speed ◽  
Distributed Parameter ◽  
Predictive Capability ◽  
Valve Spring ◽  
Coulomb Damping ◽  
System Components ◽  
Cam Follower ◽  
Distributed Parameter Modeling

A highly accurate and predictive dynamic model of a high-speed cam-follower system has been developed and verified. In view of the predominance of Coulomb damping in high-speed cam-follower systems, this form of damping has been used as the chief mode of energy dissipation. This has resulted in a significant improvement in the predictive capability of the dynamic model. The accuracy of the model can also be attributed to careful modeling of system components such as the distributed-parameter modeling of the valve spring, the modeling of the hydraulic lifter, and modeling of the damping due to a nested-valve spring. The latter two represent the first such modeling in the area of cam-follower systems.

scholarly journals The Dynamic Response of Tuned Impact Absorbers for Rotating Flexible Structures

2005 ◽  
Vol 1 (1) ◽  
pp. 13-24 ◽  
Author(s):  
Steven W. Shaw ◽  
Christophe Pierre
Keyword(s):  
Dynamic Response ◽  
Flexible Structures ◽  
Experimental Studies ◽  
Analytical Investigation ◽  
Design Parameters ◽  
System Response ◽  
Rotor Speed ◽  
Flexible System ◽  
Restoring Forces ◽  
And Performance

This paper describes an analytical investigation of the dynamic response and performance of impact vibration absorbers fitted to flexible structures that are attached to a rotating hub. This work was motivated by experimental studies at NASA, which demonstrated the effectiveness of these types of absorbers for reducing resonant transverse vibrations in periodically excited rotating plates. Here we show how an idealized model can be used to describe the essential dynamics of these systems, and used to predict absorber performance. The absorbers use centrifugally induced restoring forces so that their nonimpacting dynamics are tuned to a given order of rotation, whereas their large amplitude dynamics involve impacts with the primary flexible system. The linearized, nonimpacting dynamics are first explored in detail, and it is shown that the response of the system has some rather unique features as the hub rotor speed is varied. A class of symmetric impacting motions is also analyzed and used to predict the effectiveness of the absorber when operating in its impacting mode. It is observed that two different types of grazing bifurcations take place as the rotor speed is varied through resonance, and their influence on absorber performance is described. The analytical results for the symmetric impacting motions are also used to generate curves that show how important absorber design parameters—including mass, coefficient of restitution, and tuning—affect the system response. These results provide a method for quickly evaluating and comparing proposed absorber designs.

Application of Optimal Control Theory to the Synthesis of High-Speed Cam-Follower Systems. Part 1: Optimality Criterion

1983 ◽  
Vol 105 (3) ◽  
pp. 576-584 ◽  
Author(s):  
M. Chew ◽  
F. Freudenstein ◽  
R. W. Longman
Keyword(s):  
Optimal Control ◽  
Control Theory ◽  
Dynamic Response ◽  
Optimal Control Theory ◽  
High Speed ◽  
Integrated Approach ◽  
Optimization Criterion ◽  
Design Stage ◽  
Trade Offs ◽  
Cam Follower

The synthesis of the parameters governing the dynamic response of high-speed cam-follower systems ideally involves an integrated approach capable of carrying out the tradeoffs necessary to achieve optimum dynamic response in the design stage. These trade-offs involve a balance between the system characteristics at the output and at the cam-follower interface. In this investigation optimal-control theory has been demonstrated to be a useful tool in developing such a tradeoff. Part 1 describes the development of an optimization criterion while Part 2 describes the application of optimal-control theory to the evaluation of system parameters satisfying the optimization criterion.

scholarly journals A New Mathematical Modeling Method for Four-Stage Helicopter Main Gearbox and Dynamic Response Optimization

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Yuan Chen ◽  
Rupeng Zhu ◽  
Guanghu Jin ◽  
Yeping Xiong ◽  
Jie Gao ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Sensitivity Analysis ◽  
Dynamic Response ◽  
Dynamic Model ◽  
Structural Parameters ◽  
Modeling Method ◽  
System Response ◽  
Analysis Method ◽  
Lumped Mass ◽  
Sensitivity Analysis Method

A new mathematical modeling method, namely, the finite element method and the lumped mass method (LMM-FEM) mixed modeling, is applied to establish the overall multinode dynamic model of a four-stage helicopter main gearbox. The design of structural parameters of the shaft is the critical link in the four-stage gearbox; it affects the response of multiple input and output branches; however, only the meshing pairs were frequently shown in the dynamic model in previous research. Therefore, each shaft is also treated as a single node and the shaft parameters are coupled into the dynamic equations in this method, which is more accurate for the transmission chain. The differential equations of the system are solved by the Fourier series method, and the dynamic response of each meshing element is calculated. The sensitivity analysis method and parameter optimization method are applied to obtain the key shaft parameters corresponding to each meshing element. The results show that the magnitude of dynamic response in converging meshing pair and tail output pair is higher than that of other meshing pairs, and the wall thickness has great sensitivity to a rotor shaft. In addition, the sensitivity analysis method can be used to select the corresponding shaft node efficiently and choose parameters appropriately for reducing the system response.

Influence of a flexible wheelset on the dynamic responses of a high-speed railway car due to a wheel flat

2017 ◽  
Vol 232 (4) ◽  
pp. 1033-1048 ◽  
Author(s):  
Xingwen Wu ◽  
Subhash Rakheja ◽  
AKW Ahmed ◽  
Maoru Chi
Keyword(s):  
Dynamic Response ◽  
Dynamic Model ◽  
High Speed ◽  
Dynamic Responses ◽  
Vertical Acceleration ◽  
High Speed Train ◽  
Multibody Dynamic ◽  
Flexible Track ◽  
Wheel Flat ◽  
Track Slab

Large magnitude impact loads caused by wheel flats may excite various vibration modes of wheelsets employed in high-speed trains and thereby contribute considerably to the dynamic response of vehicles. In this study, the wheelset is modeled as a flexible body using the modal approach, which is integrated to a multibody dynamic model of the high-speed train coupled with a flexible track slab model. The multibody dynamic model is formulated for a typical high-speed train consisting of a car body, two bogie frames, and four wheelsets. The track is modeled considering the rail as a Timoshenko beam discretely supported on a flexible track slab. The effects of the wheelset flexibility on the dynamic response are illustrated through comparisons with those obtained with a rigid wheelset considering different vehicle speeds and sizes of the wheel flat. Subsequently, the effects of wheel flats on the vehicle–track system are evaluated in terms of the wheel–rail impact forces, axle-box vertical acceleration, and dynamic stress developed in the wheelset due to a haversine wheel flat. The results suggest that the wheelset flexibility can lead to significantly higher axle-box vibration and wheelset axle stress compared to a rigid wheelset in the presence of a wheel flat.

On the Dynamic Behavior of High Speed Mechanical Systems

1999 ◽  
Author(s):  
L. Yuan ◽  
J. Rastegar
Keyword(s):  
Dynamic Response ◽  
High Speed ◽  
Mechanical Systems ◽  
System Response ◽  
Structural Flexibility ◽  
State Behavior ◽  
Actuation Mechanism ◽  
Existence Of Periodic Solutions ◽  
Simulation Results ◽  
Steady State Behavior

Abstract This article reports a study of the steady state behavior of mechanical systems with nonlinear dynamics in the presence of dynamic response limitations of the actuation mechanism and in the presence of structural flexibility. In particular, the effects of such dynamic response limitations on the periodicity of the system response are studied and conditions for the existence of periodic solutions are derived. The structural flexibility is shown to increase the number of significant harmonics of the required actuating torques. A number of examples together with computer simulation results verifying the aforementioned results are presented.

Dynamic model for high-speed rotors based on their experimental characterization

2017 ◽  
Vol 2 (4) ◽  
pp. 25
Author(s):  
L. A. Montoya ◽  
E. E. Rodríguez ◽  
H. J. Zúñiga ◽  
I. Mejía
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Experimental Characterization ◽  
Rotating Systems ◽  
Computing Performance ◽  
The Impact ◽  
Stiffness Distribution ◽  
Good Agreement

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.

The Effect of Strain Rate on the Material Characteristics of Nickel-Based Superalloy Inconel 718

2007 ◽  
Vol 340-341 ◽  
pp. 283-288 ◽  
Author(s):  
Jung Han Song ◽  
Hoon Huh
Keyword(s):  
Dynamic Response ◽  
High Strain Rate ◽  
Strain Rate ◽  
Turbine Blade ◽  
Inconel 718 ◽  
High Speed ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Experimental Results ◽  
Stress Wave Propagation

The dynamic response of the turbine blade materials is indispensable for analysis of erosions of turbine blades as a result of impulsive loading associated with gas flow. This paper is concerned with the dynamic material properties of the Inconel 718 alloy which is widely used in the high speed turbine blade. The dynamic response at the corresponding level of the strain rate should be acquired with an adequate experimental technique and apparatus due to the inertia effect and the stress wave propagation. In this paper, the dynamic response of the Inconel 718 at the intermediate strain rate ranged from 1/s to 400/s is obtained from the high speed tensile test and that at the high strain rate above 1000/s is obtained from the split Hopkinson pressure bar test. The effects of the strain rate on the dynamic flow stress, the strain rate sensitivity and the failure elongation are evaluated with the experimental results. Experimental results from both the quasi-static and the high strain rate up to 3000/s are interpolated in order to construct the constitutive relation that should be applied to simulate the dynamic behavior of the turbine blade made of the Inconel 718.

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