Author : Jong-Yun Yoon
Publisher :
ISBN 13 :
Total Pages : 202 pages
Book Rating : 4.:/5 (682 download)
Book Synopsis Quasi-linear Dynamic Models of Hydraulic Engine Mount with Focus on Interfacial Force Estimation by : Jong-Yun Yoon
Download or read book Quasi-linear Dynamic Models of Hydraulic Engine Mount with Focus on Interfacial Force Estimation written by Jong-Yun Yoon and published by . This book was released on 2010 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: This dissertation proposes indirect methods to estimate dynamic forces that are transmitted by a fixed or free decoupler type hydraulic engine mount to a rigid or compliant base. The estimation processes detailed models of the hydraulic mount, and motion and/or internal pressured measurements. Linear system transfer functions that relate the force transmitted to the top chamber pressure and excitation displacement are first derived in the Laplace and frequency domains; these clearly identify the roles of rubber and hydraulic force paths up to 50 Hz. Since hydraulic mounts are inherently nonlinear, a new quasi-linear model is developed that incorporates spectrally-varying and amplitude-sensitive parameters such as top chamber compliance and rubber path properties (stiffness and damping). Alternate schemes based on a quasi-linear fluid system model of the mount are formulated. These work well in frequency domain as dynamic force spectra over a range of harmonic displacement excitations are successfully predicted given motion and/or pressure measurements. In particular, the force to pressure transfer function model is quite promising. Conversely, the analogous mechanical system model fails as it yields highly inaccurate forces. Next, experimental data from the non-resonant dynamic stiffness test are investigated in both time and frequency domains. In particular, the super-harmonic contents in fluid chamber pressure and force time histories are examined using both measurements and mathematical models. Linear time-invariant, nonlinear and quasi-linear fluid and mechanical system models are proposed to predict the transmitted force time history under sinusoidal excitation conditions given measured (or calculated) motion and/or internal pressure time histories. Several alternate indirect schemes for estimating dynamic forces are formulated. In particular, the quasi-linear model with effective system parameters, say in terms of force to pressure or force to motion transfer functions, is found to correlate well with measured dynamic forces though linear time-invariant and nonlinear models could be employed as well. Finally, a new indirect measurement concept is developed to estimate interfacial dynamic forces by employing the hydraulic mount as a dynamic force sensor. The proposed method utilizes a combination of linear mathematical models and operating motion and/or pressure measurements. A laboratory experiment, consisting of a powertrain, three powertrain mounts including a dynamic load sensing hydraulic mount, a sub-frame, and 4 bushings, is then constructed to verify the proof of the concept. Quasi-linear fluid and mechanical system models of the experiment are proposed and evaluated in terms of eigenvalues, transfer functions and forced sinusoidal responses. The lower chamber pressure in the hydraulic mount is also estimated as it was not measured. This leads to a better estimation of effective rubber and hydraulic path parameters with spectrally-varying and amplitude-sensitive properties up to 50 Hz. The reverse path spectral method is finally employed to predict interfacial forces at both mount ends by using measured motions and upper chamber pressure signals. Overall, the proposed fluid system model yields better prediction of forces when compared with the direct measurements of the dynamic forces though simpler mechanical models provide some insights. This work also advances prior component and transfer path type studies by providing an improved system perspective.
