Automotive Science and Engineering

---

By new advancements in vehicle manufacturing vehicle quality evaluation and assurance has become a more critical issue. In present work, the vibration transfer path analysis and vibration path ranking of a car interior has been performed. The method is similar to classical multilevel TPA methods but has distinct differences. The method is named VIVS which stands for Vehicle Interior Vibration Simulation. Performance of some tests like chassis dyno test, virtual mass function test and body transfer function test are required in this approach. The accelerations on both sides of the engine mounts are measured on chassis dyno by which the virtual mass and body transfer functions are measured at engine mounts. Using the concept of multilevel TPA, the vibration share from each path is calculated. The overall vibration magnitude at target point is calculated by summing the shares. Path ranking can be done by having the share of each path from overall vibration magnitude. Using this method on a sample vehicle, some modification has been proposed to decrease the vibration at target point, and the side effect of the modifications on the powertrain dynamic behavior has been evaluated. The proposed method needs less analysis time than classical TPA methods and its ability in optimization of vibration magnitude at target points is proven.

---

The constitutive relationships of the rubber materials that act as the main spring of a hydraulic engine mount are nonlinear. In addition to material induced nonlinearity, further nonlinearities may be introduced by mount geometry, turbulent fluid behavior, temperature, boundary conditions, decoupler action, and hysteretic behavior. In this research all influence the behavior of the system only certain aspects are realistically considered using the lumped parameter approach employed. The nonlinearities that are readily modeled by the lumped parameter approach constitute the geometry and constitutive relationship induced nonlinearity, including hysteretic behavior, noting that these properties all make an appearance in the load-deflection relationship for the hydraulic mount and may be readily determined via experiment or finite element analysis. In this paper we will show that under certain conditions, the nonlinearities involved in the hydraulic mounts can show a chaotic response.

---

Car design incorporates many engineering sciences where today, have led to the use of advanced technologies in automobiles to provide more satisfaction and comfort for the passengers, increase the quality of vehicles, efficiency and more pleasure than previous cars. These issues can be categorized into two groups in general. In the first group, the effects and performance of components involved in vehicle vibrations are considered, and in the second group, attention is paid to the importance of joints and junctions of these components. Heretofore, in order to minimize vehicle NVH (noise, vibration and harshness), an exuberance of efforts have been done to raise the passengers comfort. In the meantime, it should be noted that the engine mounts play a considerable and serious role in reducing vibration exchanged between the engine and chassis. In designing the engine mounts, the most important concern is to balance the two opposite criteria that come into the car as a result of different vibration inputs (road and motor). Generally, vehicle engine mounts are used by three types of targets (motor bearing weight, motor vibration absorption, motor overloading, acceleration or braking). With the development of the automotive industry, the tendency towards the use of more efficient engine mount categories, has been prepared.
This article describes a concise functional overview of the engine mount in automobiles; it illustrates operating frequency range, relationship of the P and boundary diagram of engine mounts with other car collections, torque roll axis, positioning public types of the car’s engine mounts; and it also compares their operations. Afterwards, the structure and the basic functional of hydraulic engine mount are described as the most common engine mount categories. Finally, advantages and disadvantages of various types engine mounts with capability of use in the vehicle (including elastomeric, hydraulic (with inertia track or/and decouplier or/and bell plate (plunger), semi-active (switchable) and active hydraulic engine mount) are compared with each other.

---

A combined hydraulic engine mount and buffer is proposed in this study for use in the mid-priced vehicle. In some vehicle design projects, an engine is selected to use in a new car design. To achieve the desired vibration conditions, the mount can be redesigned with exorbitant costs and long-term research. The idea of using a buffer in the combination of the conventional engine mount is to suggest a solution with affordable price which can improve mount vibration specifications. As a case study, the engine of Renault L90 (Dacia Logan), which name is K4M engine, is selected to use in the national B class automotive platform design. This automotive platform is designed at Automotive Engineering Research Center of Iran University of Science and Technology. The hydraulic engine mount is modeled in CATIA. Some tests are done to validate the simulation results. The conventional and buffer-equipped mount characteristics, which are determined by CATIA, is imported to Adams/Vibration software to evaluate the vibration behavior of the engine mounts. The results show that the use of buffer reduces the stiffness of mount, which should be 2 to 3 times lower than engine's frequency excitation. In some directions, the buffer-equipped mount has a better modal energy and isolation characteristics.

---

Elastomeric engine mounts are being used in heavy vehicles as well as passenger cars to absorb the vibrations of the engine, carry its weight and reduce its movement while driving. The aim of this research is some studies that have been done to find the components of the elastomeric compound. Moreover, the feasibility study of constructing three different specimens with different percentages of soot and oil has been carried out in order to achieve the desired characteristics in the heavy vehicle engine mount. A rheometric test was then performed to determine the temperature and time of sintering. The tensile strength test has been used to determine the elasticity of the rubber specimens and to achieve high damping coefficients. Also the tensile strength test was performed with the aim of obtaining a specimen with a suitable stress-strain relationship and comparing the results with the reference engine mount. Consequently, the elastomeric compound is used to make the elastomeric engine mount of heavy duty vehicle in the form of rubber and reverse engineering.