Variability analysis of vibrational responses in a passenger car considering the uncertainties of elastomers

Abstract

Passenger cars have many elastomeric joints that are used to reduce the vibration transmission from the source to the cabin structure. In the design stage, the dynamic characteristics of the elastomeric joints are optimally determined in order to satisfy the design goals for interior noise and vibration. However, the material properties of the elastomeric joints have large variations due to production variability. In addition, operational conditions, e.g. environmental temperature, vary according to the locations of the car. As a result, the vibrational comfort of a passenger car exhibits large variations. In this paper, the amount of vibration fluctuation due to uncertain elastomeric joint parameters is estimated using a statistical approach. First, the dynamic characteristics of the elastomers are described using the fractional derivative model. The uncertainties of the fractional derivative model parameters of the elastomers are characterized using a statistical calibration approach based on specimen test data. Then, a finite element model for the elastomers and the passenger car structure are constructed in order to calculate the vibrational response. In order to estimate the variability of the vibrational response due to the uncertainties of the elastomers, uncertainty propagation analyses are conducted using the eigenvector dimension reduction (EDR) method. The operational conditions such as temperature are also included in the variability analysis. The performance of the EDR method is assessed through comparing the estimated response distribution with that of the Monte Carlo simulation (MCS) method in a simplified structure. The variability analysis results demonstrate that the vibrational response variation due to the uncertainties of the elastomers can be efficiently predicted using the proposed method. The proposed variability analysis procedure could be an effective tool in the design stage for quality control of passenger car comfort.

Predictive Model of an Elastomer for Dynamic Properties under Thermal Environment

“…Among them, thermo-oxidative aging is a dominant factor in the degradation of mechanical properties in elastomers. The dynamic characteristics of elastomers are also heavily dependent upon frequency and operational temperature (Jung et al 2011;Kwon and Lee 2015;Lee and Hwang 2011;Lee et al 2016). In this paper, a variability analysis procedure for the thermal oxidative aging for elastomers is described.…”

The uncertainty in stiffness and damping of an automotive vehicle’s trim-structure mounts and its effect on the variability of the vibration transfer function

“…For example, Resh 14 investigated the uncertainty in the dynamic properties of engine mounts while Donders et al 15 used a Monte Carlo simulation to study the variation in the natural frequencies of an automotive vehicle body-in-white arising from the uncertainty in the spot welds 1 characteristics. The variability in the natural frequencies of a car windscreen due to temperature is studied by Scigliano et al 16 More recently, Kwon and Lee 17 modelled the uncertainty in the elastomeric joints and used the eigenvector dimension reduction method in order to obtain the variability in the dynamic response of the vehicle. They showed that the acceleration on the seat track can vary up to 6 dB due to the uncertainty in the sub-frame elastomer mounts.…”

“…The variability in the natural frequencies of a car windscreen due to temperature is studied by Scigliano et al. 16 More recently, Kwon and Lee 17 modelled the uncertainty in the elastomeric joints and used the eigenvector dimension reduction method in order to obtain the variability in the dynamic response of the vehicle. They showed that the acceleration on the seat track can vary up to 6 dB due to the uncertainty in the sub-frame elastomer mounts.…”