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As an important vibration damping element in automobile, the rubber mount can effectively reduce the vibration transmitted from the engine to the frame. In this study, a method of parameters identification of Mooney-Rivlin model by using surrogate model was proposed to more accurately describe the mechanical behavior of mount. Firstly, taking the rubber mount as the research object, the stiffness measurement was carried out. And then the calculation model of the rubber mount was established with Mooney-Rivlin model. Latin hypercube sampling was used to obtain the force and displacement calculation data in different directions. Then, the parameters of the Mooney-Rivlin model were taken as the design variables. And the error of the measured force-displacement curve and the calculated force-displacement curve was taken as the system response. Two surrogate models, the response surface model and the back-propagation neural network, were established. In addition, their prediction accuracy was compared and analyzed. For the prediction accuracy, the response surface model is more accurate than the back-propagation neural network. Finally, the surrogate model was combined with crow search algorithm to obtain the minimum error between the measured force-displacement curve and the calculated force-displacement curve. And the parameters of the Mooney-Rivlin model were identified with the presented method. The results show that the relative errors between the calculated stiffness and the measured stiffness in the three directions are less than 3%, which proving the identified parameters are accurate.

Rubber mounts are the vital component to reduce the vibration translated from the powertrain to the vehicle body. The dynamic stiffness of the conventional rubber mount increase with the increase of the excitation frequency, and form a peak under high-frequency excitation in the battery electric vehicle (BEV). So the double isolation rubber mount has gradually been used in the BEV powertrain to improve the vibration isolation performance in the high-frequency range. Compared with conventional rubber mounts, the double isolation rubber mount has smaller dynamic stiffness in the high-frequency range. However, the traditional simulation model of the dynamic characteristics cannot consider the influence of the metal bracket of the double isolation rubber mount on the dynamic characteristics. Therefore, it is necessary to carry out the modeling and analysis of the dynamic characteristics simulation model of the double isolation rubber mount. In this paper, a general dynamic model of double isolation rubber mounts is proposed to describe the high-frequency dynamic characteristics. In this general dynamic model, the complex stiffness element representing the viscoelasticity of rubber is expressed using the fractional derivative model and the Maxwell model, respectively, and two high-frequency dynamic models are established. Two model parameter identification methods are proposed for high-frequency dynamic models of double isolation rubber mounts, and the identification results are compared and analyzed. Then, two high-frequency dynamic models are used to simulate the high-frequency dynamic characteristics of double isolation rubber mounts. The simulation results show that both high-frequency dynamic models can calculate the high-frequency dynamic characteristics of double isolation rubber mounts. Among them, the dynamic model based on fractional derivative elements has relatively high accuracy, and the dynamic model based on Maxwell elements has relatively high stability. The high-frequency dynamic characteristic modeling method of double isolation rubber mounts presented in this paper is helpful to the vibration and noise analysis of electric vehicle powertrain systems under high-frequency excitation.

The rubber isolator is a key component connecting the vehicle body and the powertrain, which plays a significant role in reducing the vibration transmission from the engine to the vehicle body. With the development of electric vehicles, the excitation frequency generated by the powertrain can exceed 2 kHz. The conventional dynamic models are usually used to simulate the low-frequency dynamic characteristics of rubber isolators, in the range of 0–200 Hz, which is the main excitation frequency range of the traditional internal combustion engine vehicle. However, they cannot simulate the high-frequency dynamic characteristics accurately since the inertial force caused by the mass of rubber isolators increases greatly under high frequencies. And the high-frequency dynamic characteristics of rubber isolators is of great significance for isolator fatigue life prediction, powertrain system vibration isolation design and noise control caused by the high-frequency resonance of the isolator. In this paper, a general model with mass elements is proposed to describe the effect of the inertial force on high-frequency dynamic stiffness. Based on the proposed model and considering the different expressions of the viscoelastic properties of rubber isolators, three improved dynamic models of rubber isolators are established, and used to analyze the high-frequency dynamic characteristics of rubber isolators. It has been demonstrated that the inertial force plays a non-negligible role in the dynamic characteristics of rubber isolators under high-frequency excitation. The proposed model can be used to analyze the effect of the inertial force on the dynamic characteristics at high frequencies accurately. The high-frequency dynamic characteristic modeling method of rubber isolators presented in this paper is helpful to the vibration and noise analysis of electric vehicle powertrain systems under high-frequency excitation.

In order to get the excitation forces of the vehicle powertrain, a six-degree-of-freedom model of the powertrain mounting system is established. Two different identification methods are presented. Through the test of mount dynamic response, the powertrain excitations identified through these two methods are compared. The results show that the powertrain excitations identified through two methods are basically the same, since the mount accelerations at the body side are really small. The identified excitation is verified by comparing the deformation of torque strut. The robustness analysis of the mount acceleration phase affecting the identification results is also proposed. Improving the accuracy of phase in test input is helpful to improve the accuracy of identification results.

The design logic and calculation method for determining mount stiffness and damping for a Powertrain Mounting System (PMS) based on reductions of vehicle vibration and noise contributed by mounts is proposed in this paper. Firstly, the design target for a PMS with regard to vibration and noise limitations of vehicle level contributed form mounts is described. Then a vehicle model with 13 Degree of Freedoms (DOFs) is proposed, which includes 6DOFs for the powertrain, 3 DOFs for the car body and 4DOFs for the four unsprung mass, and the dynamic equation for the model is derived. Some widely used models, such as the 6 DOFs model of the powertrain for the design calculation of a PMS, the 7 DOFs model (Body’s 3 DOFs; unsprung mass’s 4 DOFs) and the 9 DOFs model (powertrain’s 6 DOFs; Body’s 3 DOFs) for ride analysis of a vehicle, are the specific cases of the presented model of 13 DOF. Thirdly, the calculation method for obtaining the vibration of seat track and evaluation point and the noise at driver right ear is presented based on the mount forces and the vibration and noise transfer functions. An optimization process is proposed to get the mount stiffness and damping based on minimization of vehicle vibration and noise, and the optimized stiffness is validated by comparing the calculated vibration and noise and limitations. In the end of this paper, the natural frequencies and mode energies for the powertrain, the body and the unsprung mass are calculated using different models and the results are compared and analyzed.

Compared with unbalance forces and moments of four- and six-cylinder engines, forces and moments applied to the engine block from a three-cylinder engine are large and the mechanism for balancing the unbalance forces are complex. So design of a mounting system for the powertrain with a three-cylinder engine is more challenging. This paper presents the analytical methods for obtaining the unbalance forces and moments applied to the engine block for a three-cylinder engine with or without balance measures, and develops a design methodology for the Powertrain Mounting System with a three-cylinder engine. The unbalance forces and moments generated by cylinders, crank and connecting rod mechanisms and applied to the engine block are analyzed firstly. Then, three balance methods for reducing the forces and moments applied to the engine block are proposed and discussed. Three balance measures are described and analyzed. The methods for estimating forces and moments applied to the engine block under the three balance measures are developed and compared. Thirdly, an optimization method is proposed to estimate mount stiffness based on minimization of mount forces transmitted to the car body or sub-frame, along with meeting requirements for placing natural frequencies of the powertrain in prescribed ranges and those for maximizing modal energy distributions of the powertrain in six directions. An example is given to validate the calculation methods and design philosophy for the mounting system of a powertrain with a three-cylinder engine.

Elastomeric isolators are used in a variety of different applications to reduce noise and vibration. Using isolators effectively requires the product design and development engineer to satisfy multiple objectives, which typically include packaging restrictions, environmental criteria, limitations on motion control, load requirements, and minimum fatigue life, in addition to vibration isolation performance. An understanding of elastomeric material properties and the methods used to characterize elastomeric component behavior is necessary to achieve desired performance. Typical design criteria and functional objectives for various isolator applications, including powertrain mounts, suspension control arm bushings, shock-absorber bushings, exhaust hangers, flexible couplings, cradle mounts, body mounts, and vibration dampers are also discussed. Keywords: rubber components; NVH ; automotive industry; vibration isolation; powertrain mounting system