At present, the widely used metal spring stress and deformation calculation formula is derived from material mechanics. Without a certain amount of practical experience, it is difficult to design and manufacture high-precision springs, along with the progress of design stress, the past experience is no longer used.
In recent years, the design method of the finite element of spring has entered the practical stage, and a lot of practical speeches have been made, such as the effect of the spiral angle on spring stress, the relationship between stress and fatigue life calculated by finite element method, etc. The comparison of stress is calculated using the current design method and the finite element method is analyzed. For the same structure of the spring, under the same load, it can be seen from the figure, the effective ring less or the helix angle of the high stress spring stress pressure, the results of the two methods are relatively large difference. This is due to the increase of the spiral angle, increase the load eccentricity, so that the outer diameter of the spring or lateral deformation is larger, so the stress is relatively large. The current design calculation method can not be reflected locally, and the law of finite element can be more local reaction.
For example, as the design stress of the metal spring progresses, the helical angle increases, which shifts the exhaustion source of the spring from the inside of the reed ring to the outside. To this end, it is necessary to use spring precision analysis technology, the current application of a wide range of methods is finite element method. The characteristic of the vehicle suspension spring is that in addition to sufficient fatigue life, its permanent deformation should be small, that is, anti-relaxation function to be in the defined range, otherwise because of the different deformation of the spring, the body center of gravity will occur. At the same time, consider the effects of environmental erosion on their fatigue dye life.
With the increase of vehicle maintenance period, the permanent deformation and fatigue life are put forward more stringent requirements, for which it is necessary to use high-precision design methods. The finite element method can guess the effect of spring stress fatigue life and permanent deformation, and can correctly reflect the relationship between spring fatigue life and permanent deformation of the material.
Spring design has made some progress in the use of reliability technology, but to further improve, data development and accumulation is required. With the development of computer technology, at home and abroad to compile a variety of versions of the spring design program, for the metal spring technical staff to provide a convenient premise for the development of different. The design program is used to complete the development of the curved clutch spring and drum suspension spring, which are more difficult to design. With the development of spring application technology, but also to the designers put forward a lot of need to pay attention to and solve the new topic.
Such as materials, pressure and shot treatment on the effects of fatigue and relaxation function, design is difficult to cut when calculating, rely on experimental data to determine. Also, according to the current design formula to find the number of laps, the spring stiffness made than the design stiffness value is smaller, need to reduce the effective number of laps, in order to meet the design requirements. The current design trend of high-volume production products, taking the maximum working stress and fatigue life requirements as an example.
Spring finite element analysis method, although the high level of spring technology in the country has entered practical, although China has the technical development of this aspect, but has not yet formed a practical model. In addition, an optimized design has been introduced in the design process of the spring. The structure of the spring is simple, the function is simple, the influence structure and function of the parameter variables are less, so the designer early use of the analysis method, the illustration method or the illustration analysis method to find the best design, and achieved some results.
With the development of computing technology, the optimization design of non-linear planning by computer has achieved effective reliability design is a series of analysis and design techniques used to ensure the reliability of the products designed, and its function is to make the design edited on the basis of the possible failure of the products, so that the designed products reach the defined reliability target value, which is a supplement and perfection of the traditional design methods.