A new method for the accurate measurement of higher-order frequency response functions of nonlinear structural systems

2018 ◽  
Vol 81 ◽  
pp. 270-285 ◽  
Author(s):  
R.M. Lin ◽  
T.Y. Ng
Keyword(s):  
Frequency Response ◽  
Higher Order ◽  
New Method ◽  
Structural Systems ◽  
Response Functions ◽  
Frequency Response Functions ◽  
Nonlinear Structural

Characterization of automotive dampers using higher order frequency response functions

1997 ◽  
Vol 211 (3) ◽  
pp. 181-203 ◽  
Author(s):  
S Cafferty ◽  
G. R. Tomlinson
Keyword(s):  
Energy Transfer ◽  
Frequency Response ◽  
Ride Comfort ◽  
Higher Order ◽  
Suspension System ◽  
Response Functions ◽  
Frequency Response Functions ◽  
Damping Coefficients ◽  
Non Linear ◽  
Linear Behaviour

Automotive dampers are an important element of a vehicle's suspension system for controlling road handling and passenger ride comfort. Many automotive dampers have non-linear asymmetric characteristics to accommodate the incompatible requirements between ride comfort and road handling, thus the ride comfort engineer requires techniques that can characterize this non-linear behaviour and provide models of the dampers for use in ride performance simulations of the full suspension system. The work presented in this paper is concerned with developing a frequency domain technique using higher order frequency response functions (HFRFs) to characterize a Monroe automotive damper. The principal diagonals and multidimensional surfaces of the HFRFs up to third order are obtained. Non-linear damping coefficients for the damper are derived from the HFRFs and the energy transfer properties are investigated. The results show that the majority of the HFRFs contain no peaks or resonances, indicating that the damper has no preferred frequencies for energy transfer. The accuracy of the damping coefficients determined from the HFRFs is poor. This is due to the inability of the technique to measure the pure HFRFs and separate the effects of non-linearities in the input actuator from those in the damper. It is concluded that these constraints currently impose some limit on the use of the methodology.

Calculation of Component Mode Synthesis Matrices From Measured Frequency Response Functions, Part 1: Theory

1998 ◽  
Vol 120 (2) ◽  
pp. 503-508 ◽  
Author(s):  
J. A. Morgan ◽  
C. Pierre ◽  
G. M. Hulbert
Keyword(s):  
Frequency Response ◽  
Component Mode Synthesis ◽  
New Method ◽  
Response Functions ◽  
Frequency Response Functions ◽  
Measured Frequency ◽  
Experimental Implementation ◽  
Measured Frequency Response ◽  
Expansion Coefficients ◽  
Theoretical Developments

This paper presents a new method to calculate the so-called Craig-Bampton component mode synthesis (CMS) matrices from measured frequency response functions. The procedure is based on a modified residual flexibility method, from which the Craig-Bampton CMS matrices are recovered. Experimental implementation of the method requires estimating the modal parameters corresponding to the measured free boundary modes and the Maclaurin series expansion coefficients corresponding to the omitted modes. Theoretical developments are presented in the present paper, Part 1. The performance of the new method is then demonstrated in Part 2 (Morgan et al., 1998) by comparison of experiment and analysis for a simple two-beam system.

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