Prediction and Evaluation of Sensitivity to Transient Accelerations

1954 ◽  
Vol 21 (4) ◽  
pp. 371-380
Author(s):  
M. Kornhauser
Keyword(s):  
Field Measurements ◽  
Laboratory Methods ◽  
Single Degree Of Freedom ◽  
Acceleration Time ◽  
Single Degree ◽  
Spring System ◽  
Service Conditions ◽  
Sensitivity Data ◽  
Mass Spring ◽  
The Ideal

Abstract The determination, presentation, and interpretation of inertia-sensitivity data are discussed with application to inertia devices and to shock-resistant structures. Theoretical analysis of the single-degree-of-freedom system for response to acceleration-time pulses, amplification factors, and inertia sensitivity are used as a basis for discussion of actual devices. Effects of deviations from the ideal mass-spring system are considered. Practical use of sensitivity data is discussed with regard to the reliability of laboratory methods, the accuracy of field measurements, and variability of service conditions. Criteria are suggested for design of inertia mechanisms and design of structures for resistance to shock.

scholarly journals Complex-Damped Dynamic Systems in the Time and Frequency Domains

2004 ◽  
Vol 11 (3-4) ◽  
pp. 209-225 ◽  
Author(s):  
Elvio Bonisoli ◽  
John E. Mottershead
Keyword(s):  
Frequency Response ◽  
Structural Dynamics ◽  
Dynamic Systems ◽  
Dynamic Behaviour ◽  
Root Locus ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Frequency Domains ◽  
Spring System ◽  
Mass Spring

The fact that a complex-damped model may represent the dynamic behaviour of elasto-mechanical systems when acted upon by a magnetic field was brought to the attention of the structural dynamics community very recently by Professor Bruno A. D. Piombo and his colleagues at the Politecnico di Torino. In this paper a thorough analysis of the single degree-of-freedom complex-damped mass-spring system is presented. The analysis includes the root locus, the (non-causal) impulse response, the frequency response and the transmissibility. Regions of different behaviour in the frequency response and transmissibility are described in detail. The stiffening behaviour observed in Prof. Piombo's experiments and known as the "phantom effect" is demonstrated by the complex-damped model.

On Running a Machine through its Resonant Frequency

1956 ◽  
Vol 60 (549) ◽  
pp. 620-621 ◽  
Author(s):  
J. P. Ellington ◽  
H. McCallion
Keyword(s):  
High Speed ◽  
Exciting Force ◽  
Linear Mass ◽  
Running Speed ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Constant Rate ◽  
Summation Of Series ◽  
Spring System ◽  
Mass Spring

A solution, in terms of known integrals, is obtained for the motion from rest of a machine, idealised as an undamped linear mass-spring system, when subjected to an exciting force whose frequency varies at a constant rate.In many installations of modern high speed machinery the running speed of the machine is in excess of the resonant or natural frequency of the system, and consequently starting up or stopping the machine could result in vibrations of large amplitude. The problem of assessing the magnitude and duration of these vibrations is very complicated and has been solved analytically only for the case of a single degree of freedom system excited by an oscillating force whose frequency varies linearly with time. However, even this solution is not easy to evaluate, the integrals involved demanding either graphical construction and numerical integration or summation of series.

The Active Control of Forced Vibration Produced by Arbitrary Disturbances

1985 ◽  
Vol 107 (1) ◽  
pp. 33-37 ◽  
Author(s):  
J. S. Burdess ◽  
A. V. Metcalfe
Keyword(s):  
Vibration Control ◽  
Active Control ◽  
Forced Vibration ◽  
Disturbance Observer ◽  
Degree Of Freedom ◽  
Experimental Results ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Impact Forces ◽  
Mass Spring

This paper considers the vibration control of a single degree of freedom mass-spring-damper system when subjected to an arbitrary, unmeasurable disturbance. The idea of a disturbance observer is introduced and it is shown how an estimate of the excitation can be derived and used to generate a control, which reduces the vibration. This control is shown to be robust with respect to the parameters describing the behavior of the system. Experimental results are presented which show the efficacy of the method when the system is excited by periodic, random, and impact forces. Comments are made on the application of the method.

Analytical Procedure for Prediction of Radiated Noise From a Gear-Shaft-Plate System

2000 ◽  
Author(s):  
Chan Il Park
Keyword(s):  
Circular Plate ◽  
Analytical Procedure ◽  
Housing System ◽  
Single Degree Of Freedom ◽  
Gear Noise ◽  
Radiated Noise ◽  
Gear Mesh ◽  
Single Degree ◽  
The Moment ◽  
Mass Spring

Abstract In order to predict the gear noise, a simplified model of gear-shaft-housing system is studied. The gear is modeled as a single degree of freedom mass-spring-damper system. The shaft-housing system is modeled as a clamped circular plate connected with a beam. The moment components of the beam excited by the gear mesh force are considered in the calculation of the plate vibration and radiated noise. The displacements of the clamped circular plate due to the r-direction moment and θ-direction moment are analytically derived. Radiated noise from the plate is also derived using Rayleigh integral. Using the derived results, the numerical examples are given.

An Experimental Hand/Arm Model for Human Interaction With a Telemanipulation System

2001 ◽  
Author(s):  
John E. Speich ◽  
Liang Shao ◽  
Michael Goldfarb
Keyword(s):  
Experimental Data ◽  
Second Order ◽  
Degree Of Freedom ◽  
Human Interaction ◽  
Haptic Interfaces ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Lumped Parameter ◽  
Mass Spring ◽  
System 1

Abstract This paper describes the development of a linear single degree-of-freedom lumped-parameter hand/arm model for the operator of a telemanipulaton system. The model form and parameters were determined from experimental data taken from a single degree-of-freedom telemanipulation system. Typically, the human is modeled as a second order mass-spring-damper system [1, 2]. The model developed in this paper, however, includes an additional spring and damper to better approximate the dynamics of the human while interacting with the manipulator. This model can be used in the design and simulation of control architectures for telemanipulation systems and haptic interfaces.

Streamwise Gate Vibration

2017 ◽  
pp. 204-229
Keyword(s):  
Wave Theory ◽  
Mass Effect ◽  
Added Mass ◽  
Wave Radiation ◽  
Theory Analysis ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Long Span ◽  
Mass Spring

Streamwise vibrations of gates due to the bending flexibility of the skinplate of Tainter gates or the weir plate of long-span gates result in pushing-and-drawing of the water in the reservoir. During each cycle of vibration, the gate's motion must accelerate and then decelerate the water mass in contact with the vibrating gate surface, resulting in a substantial added mass effect. From simple single degree-of-freedom mass-spring-damper vibration theory, one understands that the effect of added mass is to lower the frequency of gate vibration. In addition to the push-and-draw effect, streamwise motion can also result in discharge fluctuation for inclined gates, providing a source of gate excitation. Rayleigh's wave theory analysis from the previous chapter is applied to provide an analysis framework for determining the magnitude of wave radiation damping and to calculate the added mass.

A Closed-Form Numerical Algorithm for the Periodic Response of High-Speed Elastic Linkages

1979 ◽  
Vol 101 (1) ◽  
pp. 154-162 ◽  
Author(s):  
A. Midha ◽  
A. G. Erdman ◽  
D. A. Frohrib
Keyword(s):  
Differential Equation ◽  
Closed Form ◽  
High Speed ◽  
Order Equation ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Time Period ◽  
Governing Differential Equation ◽  
Constant Coefficients ◽  
Spring System

A numerical closed-form algorithm, easily adaptable for computer simulation, is developed to solve for the periodic solutions of vibrating systems, and in particular, the high-speed elastic linkage. The algorithm is first introduced to solve the single degree-of-freedom mass-dashpot-spring system, the governing differential equation of which is a linear, second-order equation with constant coefficients. This algorithm is utilized as a basic tool and extended to solve a single degree-of-freedom mass-dashpot-spring system whose governing differential equation of motion is a linear, second-order equation with time-dependent and periodic coefficients. The system is excited by a periodic forcing function and solution is made possible by discretizing the forcing time period into a number of time intervals, the system parameters remaining constant over the duration of each interval. During each interval, the solution form is assumed to be that of the differential equation with “constant” coefficients. Constraint equations result from imposing the conditions of “compatibility” of response at the discrete time nodes and the conditions of “periodicity” of response at the end nodes of the time period. Also, the sum of the integration required is over one forcing time period only. This closed-form nature of the computational procedure results in large savings in computer time to acquire the periodic solution. The suggested numerical algorithm is then employed to solve an elastic linkage problem.

Synthesis and Application of a Single Degree-of-Freedom Six-Bar Linkage with Mixed Exact and Approximate Pose Constraints

2020 ◽  
pp. 1-39
Author(s):  
Xiong Zhao ◽  
Chennan Yu ◽  
Jianneng Chen ◽  
Xincheng Sun ◽  
Jun Ye ◽  
...  
Keyword(s):  
Synthesis Method ◽  
Degree Of Freedom ◽  
Synthesis Methods ◽  
Test Results ◽  
Single Degree Of Freedom ◽  
Solution Domain ◽  
Rehabilitation Training ◽  
Single Degree ◽  
New Synthesis ◽  
The Ideal

Abstract Existing research on synthesis methods for single degree-of-freedom (DOF) six-bar linkages mainly include four or five exact poses. However, an ideal trajectory cannot be synthesized using only five exact poses, thus, it is necessary to introduce additional poses to constrain the trajectory. If more exact poses are introduced, then the linkage may have no solution. Therefore, the constraints of the approximate pose are considered to make the trajectory conform to the desired trajectory. This paper successfully introduces mixed poses into a six-bar linkage, based on Z (Z<5) exact poses and K approximate poses of a given error range, and a new synthesis method for single DOF six-bar linkages is proposed. The solution domain of the linkages synthesized by this method is wide and can be adjusted by controlling the error of the approximate poses, which reduces the difficulty of selecting the solution, ensures theoretical feasibility, and enables the trajectory of the final linkage to more closely match the ideal trajectory. Finally, for the coordinated training of multiple joints in human limbs, a rehabilitation device is designed based on the above six-bar linkage, and a prototype is developed and tested. The test results reveal the accuracy of the proposed method and the effectiveness of rehabilitation training.

Unexpected Scaling of Peak Acceleration for a Yielding Mass-Spring System Subjected to a Triangular Base Acceleration Pulse

2021 ◽  
pp. 1-30
Author(s):  
Michael Guthrie
Keyword(s):  
Earthquake Engineering ◽  
Full Range ◽  
Approximate Expression ◽  
Single Degree Of Freedom ◽  
Acceleration Pulse ◽  
Relative Acceleration ◽  
Spring System ◽  
Mass Spring ◽  
Nonmonotonic Behavior ◽  
Quantities Of Interest

Abstract The use of bounding scenarios is a common practice which greatly simplifies the design and qualification of structures. However, this approach implicitly assumes that the quantities of interest increase monotonically with the input to the structure, which is not necessarily true for nonlinear structures. This paper surveys the literature for observations of nonmonotonic behavior of nonlinear systems, and finds such observations in both the earthquake engineering and applied mechanics literature. Numerical simulations of a single degree of freedom mass-spring system with an elastic-plastic spring subjected to a triangular base acceleration pulse are then presented, and it is shown that the relative acceleration of this system scales nonmonotonically with the input magnitude in some cases. The equation of motion for this system is solved symbolically and an approximate expression for the relative acceleration is developed, which qualitatively agrees with the nonmonotonic behavior seen in the numerical results. The nonmonotonicity is investigated and found to be a result of dynamics excited by the discontinuous derivative of the base acceleration pulse, the magnitude of which scales nonmonotonically with the input magnitude due to the fact that first yield of the spring occurs earlier as the input magnitude is increased. The relevance of this finding within the context of defining bounding scenarios is discussed and it is recommended that modeling be used to perform a survey of the full range of possible inputs prior to defining bounding scenarios.

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