汽車安全氣囊碰撞有限元分析外文翻譯-汽車設(shè)計(jì)-文庫吧
2025-04-16 22:41 本頁面
【正文】 ide line interface (ISL) elements, and slide line elements. The finite element analysis results were in excellent agreement with experimental results for various electromechanical sensors studied in this paper. PROBLEM DEFINITION The key ponents of the electromechanical sensor analyzed are two thin metallic springs (referred to as spring1 and spring2) which are cantilevered from a rigid plastic housing and a solid metallic ball as shown in Figure 1. The plastic housing contains a hollow tube closed at one end which guides the ball in the desired direction. The ball is held in place by spring1 at the open end of the tube. When the sensor is assembled, spring1 is initially displaced by the ball which creates a preload on spring1. The ball is able to travel in one direction only in this sensor and this direction will be referred to as the xdirection (see the global coordinate system shown in Figure 2) in this paper. Once enough acceleration in the xdirection is applied to overe the preload on spring1, the ball displaces the spring. As the acceleration applied continues to increase, spring1 is displaced until it is in contact with spring2. Once Figure 1. Electromechanical automobile crash sensor. contact is made between spring1 and spring2, an electric circuit is pleted allowing the sensor to perform its function within the airbag system. FINITE ELEMENT ANALYSIS METHODOLOGY When creating a finite element representation of the sensor, the following simplifications can be made. The two springs can be fully restrained at their bases implying a perfectly rigid plastic housing. This is a good assumption when paring the flexibility of the thin springs to the stiff plastic housing. The ball can be represented by a rigid surface since it too is very stiff as pared to the springs. Rather than modeling the contact between the plastic housing and the ball, all rotations and translations are fully restrained except for the xdirection on the rigid surface representing the ball. These restraints imply that the housing Figure 2. Electromechanical sensor finite element mesh. will have no significant deformation due to contact with the ball. These restraints also ignore any gaps due to tolerances between the ball and the housing. The effect of friction between the ball and plastic is negligible in this sensor can be analyzed by applying an enforced displacement in the xdirection to the rigid surface representing the ball to simulate the full displacement of the ball. Contact between the ball and springs is modeled with various contact elements as discussed in the following section. A nonlinear static analysis is sufficient to capture the forcedisplacement response of the sensor versus using a more expensive and time consuming nonlinear transient analysis. Although the sensor is designed with a ball mass and spring stiffness that gives the desired response to a given acceleration, there is no mass associated with the ball in this static analysis. The mass of the ball can be determined by dividing the force required to deflect the springs by the acceleration input into the sensor. Mesh The finite ele
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