Finite Element Analysis Of Dynamic Characteristics For Main Rubber Spring Of Hydraulic Engine Mount

With the rapid improvement of the science and the technology, the trend of the design for the cars appears to be light-weight and low-cost. People pay more and more attention to the amenity of the cars, and the excellent riding performance and low noises came to be the typical features of the modern cars. At present, the whole motor industry focuses on the problem how to enhance the amenity of the cars. The factors affecting the amenity are so many, of all these factors, the vibration and the noise are the typical and important ones. However, the noise comes from the vibrations. In order to improve the performance of ride comfort, the vibrations should be controlled as much as possible.As the engine is the main source of vibration and noise in automobiles, the engine mount, which is designed to isolate the vibration between the engine and the chassis, plays the key role in avoiding the vibrations of the engine from the body. Meanwhile, it affects the seating comfort significantly. With the great improvement of the technology of automobiles, the traditional rubber engine mount couldn't meet the demand for the isolation system any longer. Recently, the hydraulic engine mounts are being used more and more in automobiles. Compared to the rubber engine mounts, the hydraulic one has more excellent performance of isolating the vibrations.While the engine mounts are being designed, in order to optimize the design of the engine mount system, the finite element analyzing method could be used to do the static or the dynamic characteristics analysis and make some improvements on design. Using this method could effectively enhance the quality of the vibration isolators, shorten the period of developing new products, reduce the cost of preproduction and tests. In this paper, based on the precious experience of others'research on the hydraulic engine mount, one main rubber spring of the hydraulic engine mount of the car is chosen to be the subject investigated. The main part of this paper is the analysis on the dynamic characteristics of the main rubber spring of the hydraulic engine mount using the finite element analyzing method. It consists of these four parts:1. After looking up large quantities of documentations and papers about the engine mount, the developing history of the engine mount system is reviewed and summarized. Besides this, the modeling methods of the engine mount system are illustrated according to different theories. Then choose the proper method of modeling in this paper.2. At first, the three dimensional solid model of the main rubber spring is created, then make some necessary cleanups and proper simplifications on the model referring the working environment and the stress of the main rubber spring. Define the property parameters of the materials involved in the model, and then apply the boundary conditions and the loads.3. Analyze the static characteristics of the main rubber spring by using the ABAQUS. Then design the test to make sure that the model could be appropriate and available. After being tested, the model used in this paper was proved to be available and credible.4. The finite element analyzing software ABAQUS is applied to analyze the dynamic characteristics of the main rubber spring. It is known that the types of the elements and the size of meshing scale would affect the precision of the calculating result. More attentions should be located on the types of the elements and the meshing scale in the large deformation zone. Evaluate the result by quoting two parameters: the dynamic rigidity and the lagging angle. The analysis consists of two main parts: the driving force in the first part has low frequencies but large amplitudes, in the second part with high frequencies but small amplitudes.5. In this paper, the factors which would influence the dynamic characteristics of the main rubber spring are represented in detail, especially illustrating on the stiffness of the main rubber. With the low pump frequencies, if the stiffness of the main rubber spring gets larger, the output displacement would become smaller, then the maximum of the modulus of the complex stiffness would get larger, and the maximum of the lagging angle smaller, however, the effects on the dynamic characteristics are not evident in the high pump frequencies area. The stiffness of the main rubber spring are influenced by many factors. In this paper, the analysis mainly consists of the hardness and the compressive ability of the rubber, the structures of the metal skeletons, as well as the different sections of the main rubber spring. If the rubber becomes harder, the Young's modulus will be larger, then the stiffness of the rubber spring would get larger. When the parameter of the compressive ability gets larger, the stiffness of the main spring reduces slightly. The metal skeleton of the main rubber spring could maintain the shape of the main spring, and improve the stiffness of the main spring. With the larger metal skeleton, the maximal deformation of the main rubber spring gets smaller, then the stiffness of the main spring gets larger. If the section of the main spring gets smaller, the shearing deformed rubber elements become less when loaded, then the stiffness of the main rubber spring would reduce. With the proper conditions of the manufacturing craft and the installing space, making some changes on the section area could ensure the enough stiffness of the main rubber spring.