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.

A Technique for Estimating Linear Parameters Using Nonlinear Restoring Force Extraction in the Absence of an Input Measurement

2005 ◽  
Vol 127 (5) ◽  
pp. 483-492 ◽  
Author(s):  
Muhammad Haroon ◽  
Douglas E. Adams ◽  
Yiu Wah Luk
Keyword(s):  
System Identification ◽  
Nonlinear System ◽  
Nonlinear System Identification ◽  
Restoring Force ◽  
Nonlinear Parameters ◽  
System Parameters ◽  
System Data ◽  
Vehicle Suspension System ◽  
Two Stages ◽  
Parameter Estimation Techniques

Conventional nonlinear system identification procedures estimate the system parameters in two stages. First, the nominally linear system parameters are estimated by exciting the system at an amplitude (usually low) where the behavior is nominally linear. Second, the nominally linear parameters are used to estimate the nonlinear parameters of the system at other arbitrary amplitudes. This approach is not suitable for many mechanical systems, which are not nominally linear over a broad frequency range for any operating amplitude. A method for nonlinear system identification, in the absence of an input measurement, is presented that uses information about the nonlinear elements of the system to estimate the underlying linear parameters. Restoring force, boundary perturbation, and direct parameter estimation techniques are combined to develop this approach. The approach is applied to experimental tire-vehicle suspension system data.

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.

Nonlinear System Identification Technique for a Base-Excited Structure Based on Modal Space Formulation

2016 ◽  
Vol 11 (6) ◽  
Author(s):  
Sushil Doranga ◽  
Christine Q. Wu
Keyword(s):  
System Identification ◽  
Nonlinear System ◽  
Degrees Of Freedom ◽  
Nonlinear System Identification ◽  
Model Space ◽  
Least Square ◽  
Closed Form Expression ◽  
Restoring Force ◽  
Nonlinear Restoring Force ◽  
Modal Space

Most of the nonlinear system identification techniques described in the existing literature required force and response information at all excitation degrees-of-freedom (DOFs). For cases, where the excitation comes from base motion, those methods cannot be applied as it is not feasible to obtain the measurements of motion at all DOFs from an experiment. The objective of this research is to develop the methodology for the nonlinear system identification of continuous, multimode, and lightly damped systems, where the excitation comes from the moving base. For this purpose, the closed-form expression for the equivalent force also known as the pseudo force from the measured data for the base-excited structure is developed. A hybrid model space is developed to find out the nonlinear restoring force at the nonlinear DOFs. Once the nonlinear restoring force is obtained, the nonlinear parameters are extracted using “multilinear least square regression” in a modal space. A modal space is chosen to express the direct and cross-coupling nonlinearities. Using a cantilever beam as an example, the proposed methodology is demonstrated, where the experimental setup, testing procedure, data acquisition, and data processing are presented. The example shows that the method proposed here is systematic and constructive for nonlinear parameter identification for base-excited structure.

A Technique for Estimating Linear Parameters of an Automotive Suspension System Using Nonlinear Restoring Force Extraction

2004 ◽  
Author(s):  
Muhammad Haroon ◽  
Douglas E. Adams ◽  
Yiu Wah Luk
Keyword(s):  
System Identification ◽  
Nonlinear System ◽  
Nonlinear System Identification ◽  
Suspension System ◽  
Restoring Force ◽  
Nonlinear Parameters ◽  
Automotive Suspension ◽  
Vehicle Suspension System ◽  
Direction Information ◽  
Parameter Estimation Techniques

Conventional nonlinear system identification procedures assume that the system behavior is nominally linear at a specific amplitude (usually low). The nominally linear parameters are then estimated at that particular amplitude and used to estimate the nonlinear parameters of the system. Many mechanical systems are not nominally linear over a broad frequency range for any operating amplitude. A new method for nonlinear system identification, in the absence of an input measurement, is presented that works in the opposite direction. Information about the nonlinear elements of the system is used to estimate the underlying linear parameters. Restoring force, boundary perturbation and direct parameter estimation techniques are combined to develop this approach. The approach is applied to data from an experimental tire-vehicle suspension system.

A Frequency Domain Versus a Time Domain Identification Technique for Nonlinear Parameters Applied to Wire Rope Isolators

2000 ◽  
Vol 123 (4) ◽  
pp. 645-650 ◽  
Author(s):  
Gaetan Kerschen ◽  
Vincent Lenaerts ◽  
Stefano Marchesiello ◽  
Alessandro Fasana
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Nonlinear Dynamical Systems ◽  
Wire Rope ◽  
Restoring Force ◽  
Nonlinear Parameters ◽  
Nonlinear Dynamical ◽  
Domain Identification ◽  
Identification Technique ◽  
Reverse Path Method

The present paper aims to compare two techniques for identification of nonlinear dynamical systems. The Conditioned Reverse Path method, which is a frequency domain technique, is considered together with the Restoring Force Surface method, a time domain technique. Both methods are applied for experimental identification of wire rope isolators and the results are compared. Finally, drawbacks and advantages of each technique are underlined.

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