On joint mobility design in multi-structural systems

Abstract

This article aims to develop a measure that can estimate the isolator performance in joint design problems. The relationships between the receptances of the connection points and the isolator bushes in multi-structural car-body systems are explored from the perspective of a frequency-response-function-based substructuring method. From the formulation for the frequency-response-function-based substructuring method, the desirable magnitude difference between the receptances is proposed through an order analysis of a one-dimensional system. The receptance magnitude concept is extended to a multi-structural system using a singular-value diagram. In order to represent the magnitude of the receptance matrices, matrix measures are introduced. Using the defined measures, a joint design index is proposed in order to assess the structural joint system which consists of two structures and isolator bushes. Finally, two numerical examples are used to demonstrate the relationships between the suggested joint design concept and the relevant responses (i.e. the vibrations, the force and the power) of the structures. The proposed joint design index can estimate the isolator performance and indicate the possibilities for improvement in multi-structural systems, which is very useful for noise and vibration reduction in the automotive industry.

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

“…It should be noted that the fractional derivative model parameters, log(a 1 ) and log(c 1 ), are linearly correlated, because the ratio of the parameters log(a 1 /c 1 ) physically represents the asymptotic value of the storage modulus in a high frequency region. 10 The EDR method 24 was used to generate a response PDF at a given h and a gradient-based optimizer, the ''fmincon'' function of MATLAB, 25 was used to solve the unconstrained optimization problem in equation (8). Table 1 lists the identified uncertainties in terms of the fractional derivative model parameters.…”

“…In general, the amounts of response variation differ between vehicles, even for the same elastomer, because the sensitivity of the joint in which the elastomer is attached changes according to the relative relationships of the structures. 8 Figure 15 presents the estimated variabilities of the reaction forces at the joints and the transmitted powers through the joints due to the uncertainties of the elastomers. The variabilities of the reaction forces and the transmitted powers, as depicted in Figure 15, are significantly less than the variability of the vibrational response.…”

“…As a result, uncertainties in the dynamic characteristics of the elastomers can also explain a large portion of the variability of the structural responses. 8 Elastomers consist of viscoelastic rubber and exhibit displacement-dependent and frequencydependent characteristics. 9 In addition, the operation temperature has a significant influence on the dynamic characteristics of the viscoelastic materials.…”

Component mode synthesis methods for a body-in-white noise and vibration analysis

“…In order to reduce the simulation time but to maintain highly accurate results, as explained by Klerk et al, 10 the DS is based on the principle of dividing a large structure into smaller subsystems which are easier and faster to study. 11 The DS approach is not a new way of working, since the idea was probably introduced by Hurty, 12,13 which led to a constant increase in the interest in DS, resulting in the classic methods of Craig and Bampton, [14][15][16][17] MacNeal 18 and Rubin. 19 The Craig-Bampton method uses two sets of vibrational modes to reduce the system.…”

Chiral nuclear forces: Recent developments

“…These studies have revealed the important role of the chiral 3NF yielding many promising results, see [15] and references therein. For a progress report on the discretized formulation of nuclear chiral EFT see [16]. Still, the well-known discrepancies between state-of-the-art theoretical calculations and experimental data in the three-nucleon continuum at intermediate energies of E N ∼ 50 .…”