scholarly journals Implementing the Restoring Force Surface Method to Fit Experimentally Measured Modal Coupling Effects

2020 ◽  
pp. 79-82
Author(s):  
Benjamin Moldenhauer ◽  
Daniel R. Roettgen ◽  
Benjamin Pacini
Keyword(s):  
Coupling Effects ◽  
Restoring Force ◽  
Surface Method ◽  
Modal Coupling

Fast Frequency-Domain Algorithm for Estimating the Dynamic Wind-Induced Response of Large-Span Roofs Based on Cauchy’s Residue Theorem

2018 ◽  
Vol 18 (03) ◽  
pp. 1850037 ◽  
Author(s):  
Ning Su ◽  
Zhenggang Cao ◽  
Yue Wu
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Rational Functions ◽  
Induced Response ◽  
Response Analysis ◽  
Residue Theorem ◽  
Coupling Effects ◽  
Large Span ◽  
Modal Coupling ◽  
Cauchy’S Residue Theorem

Wind-induced response analysis is an important process in the design of large-span roofs. Conventional time-domain methods are computationally more expensive than frequency-domain algorithms; however, the latter are not as accurate because of the ill-treatment of the modal coupling effects. This paper revisited the derivations of the frequency-domain algorithm and proposed a fast algorithm for estimating the dynamic wind-induced response considering duly the modal coupling effects. With the wind load cross-spectra modeled by rational functions, closed-form solutions to the frequency-domain integrals can be calculated by Cauchy’s residue theorem, rather than by numerical integration, thereby reducing the truncation errors and enhancing the efficiency of computation. The algorithm is applied to the analysis of a grandstand roof and a spherical dome. Through comparison with time domain analyses results, the algorithm is proved to be reliable. A criterion of the coupling modal combination was suggested based on the cumulative modal contribution rate of over 70%.

scholarly journals Restoring Force Surface Analysis of Nonlinear Vibration Data From Micro-Cantilever Beams

2006 ◽  
Author(s):  
Matthew S. Allen ◽  
Hartono (Anton) Sumali ◽  
David S. Epp
Keyword(s):  
Functional Form ◽  
Piecewise Linear ◽  
Cantilever Beams ◽  
Restoring Force ◽  
Vibration Data ◽  
Surface Method ◽  
Highly Nonlinear ◽  
Nonlinear Dynamic Characteristics ◽  
Restoring Forces ◽  
Micro Cantilever

The responses of micro-cantilever beams, with lengths ranging from 100-1500 microns, have been found to exhibit nonlinear dynamic characteristics at very low vibration amplitudes and in near vacuum. This work seeks to find a functional form for the nonlinear forces acting on the beams in order to aide in identifying their cause. In this paper, the restoring force surface method is used to non-parametrically identify the nonlinear forces acting on a 200 micron long beam. The beam response to sinusoidal excitation contains as many as 19 significant harmonics within the measurement bandwidth. The nonlinear forces on the beam are found to be oscillatory and to depend on the beam velocity. A piecewise linear curve is fit to the response in order to more easily compare the restoring forces obtained at various amplitudes. The analysis illustrates the utility of the restoring force surface method on a system with complex and highly nonlinear forces.

On the Non-Linear Characteristics of Automotive Shock Absorbers

1992 ◽  
Vol 206 (1) ◽  
pp. 3-16 ◽  
Author(s):  
C Surace ◽  
K Worden ◽  
G R Tomlinson
Keyword(s):  
Experimental Data ◽  
Restoring Force ◽  
Shock Absorbers ◽  
Surface Method ◽  
First Case ◽  
Non Linear ◽  
Realistic Representation ◽  
Linear System Identification ◽  
Stiffness Characteristics ◽  
Non Linear System

The objectives of this paper are essentially twofold. In the first case an experimental study of a number of shock absorbers is presented; the restoring force surface method of non-linear system identification is applied in order to determine the non-linear characteristics of the absorbers in an easily visualizable manner. In the second part, a new physical model for the absorber is presented which incorporates effects due to compressibility of the fluid in the absorber; this provides a more realistic representation of the stiffness characteristics than previous simple models. The new model is compared with the experimental data.

scholarly journals Using nonlinear jumps to estimate cubic stiffness nonlinearity: An experimental study

2016 ◽  
Vol 230 (19) ◽  
pp. 3575-3581 ◽  
Author(s):  
Bin Tang ◽  
MJ Brennan ◽  
V Lopes ◽  
S da Silva ◽  
R Ramlan
Keyword(s):  
Experimental Study ◽  
Experimental Investigation ◽  
Vibration Control ◽  
Theoretical Basis ◽  
Mechanical Design ◽  
Type System ◽  
Restoring Force ◽  
Surface Method ◽  
System Properties ◽  
Cubic Stiffness

Attempts are being made to improve mechanical design by using nonlinearity rather than eliminating it, especially in the area of vibration control and in energy harvesting. In such systems, there is a need to both predict the dynamic behavior and to estimate the system properties from measurements. This paper concerns an experimental investigation of a simple identification method, which is specific to systems in which the behavior is known to be similar to that of a Duffing-type system. It involves the measurement of jump-down frequencies and the amplitudes of displacement at these frequencies. The theoretical basis for the method is briefly described as, is an experimental investigation on a beam-shaker system. The results are comparable with those determined by the restoring force surface method. The method described in this article has the advantage that the data can be collected and processed more easily than the restoring force surface method and can be potentially more suitable for the engineering community than existing identification measures.

Investigation of Nonlinear Effects in a Bolted Joint Beam Using the Base Excitation

2020 ◽  
Author(s):  
Sushil Doranga
Keyword(s):  
Energy Levels ◽  
Nonlinear System Identification ◽  
Nonlinear Effects ◽  
Base Excitation ◽  
Restoring Force ◽  
Nonlinear Parameters ◽  
New Approach ◽  
Surface Method ◽  
Force Reconstruction ◽  
Modal Space

Abstract In this paper, the nonlinearity detection, characterization and identification of a bolted beam assembly is presented. The new approach based on the force reconstruction using the base excitation as an input is used for the identification of nonlinear parameters. The nonlinear effect in the bolted beam assembly was induced by reducing the bolt clamping loads. A collection of frequency response functions (FRFs) are shown at different clamping loads to detect and characterize the nonlinearities. Once the nonlinearities are detected and characterized, the restoring force surface method using the reconstructed force was used to identify the nonlinear parameters in the modal space. Four different base excitation (energy) levels with three different tightening torques were considered in the tests in order to study the energy dependence of the damping nonlinearities. In all the cases, the nonlinear system identification methodology employed was successful in identifying the damping and stiffness nonlinearities.

scholarly journals Validation of Two Nonlinear System Identification Techniques Using an Experimental Testbed

2004 ◽  
Vol 11 (3-4) ◽  
pp. 365-375 ◽  
Author(s):  
V. Lenaerts ◽  
G. Kerschen ◽  
J.-C. Golinval ◽  
M. Ruzzene ◽  
E. Giorcelli
Keyword(s):  
Experimental Data ◽  
Nonlinear System ◽  
Nonlinear System Identification ◽  
Physical Parameters ◽  
Free Response ◽  
Restoring Force ◽  
Surface Method ◽  
Experimental Testbed ◽  
Linear And Nonlinear ◽  
Identification Techniques

The identification of a nonlinear system is performed using experimental data and two different techniques, i.e. a method based on the Wavelet transform and the Restoring Force Surface method. Both techniques exploit the system free response and result in the estimation of linear and nonlinear physical parameters.

VTT BENCHMARK: APPLICATION OF THE RESTORING FORCE SURFACE METHOD

2003 ◽  
Vol 17 (1) ◽  
pp. 189-193 ◽  
Author(s):  
G KERSCHEN ◽  
V LENAERTS ◽  
J.-C GOLINVAL
Keyword(s):  
Restoring Force ◽  
Surface Method
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