考虑易损件的斜支承包装系统动力学特性研究

发布时间：2018-08-07 16:27

【摘要】：丰田汽车自二十世纪九十年代在北京国际汽车及工艺装备展览会上展出了弹簧减震器（斜支承减振系统），受到各工程领域的广泛关注。斜支承包装系统是由四个弹性缓冲元件将内箱体与外箱体底部连接在一起的一种结构改进缓冲包装系统，利用倾斜安装弹簧的几何非线性对发动机进行减振保护，其减振效果优于弹簧垂直悬挂的线性系统，一般应用于脆值较低的精密仪器、设备的减振保护。在物流运输过程中，产品的破损首先发生在某个或某几个脆弱部件，即易损件，将产品处理为二自由度几何结构非线性缓冲系统更贴近实际。针对考虑易损件的斜支承包装系统为研究对象，基于数值分析、牛顿第二定律及产品破损评价等理论方法，研究系统的动力学特性。主要内容如下：首先，建立系统的动力学模型。根据牛顿第二定律，建立系统二自由度动力学方程，应用泰勒级数展开进行简化处理，得到系统振动动力学方程和冲击动力学方程并进行无量纲化处理。其次，研究系统的自振特性。基于四阶龙格-库塔数值分析方法，求解振动动力学方程，得到系统易损件的位移响应和加速度响应，分析系统支承角、系统频率比、系统质量比、主体无量纲初始位移等对易损件位移、加速度响应的影响规律。结果表明，增加系统频率比、减小主体无量纲初始位移，易损件的位移响应峰值显著降低；随支承角度的减小或质量比的增加，易损件的位移响应峰值略有下降且周期延长；随系统支承角的减小、频率比的增加、主体无量纲初始位移的减小、质量比的增加，系统易损件的加速度响应峰值降低。最后，研究系统在矩形脉冲激励下的冲击特性。基于四阶龙格-库塔数值分析方法，求解冲击动力学方程，得到易损件加速度响应，并结合传统脆值理论，得到系统易损件的冲击响应谱和破损边界。结果表明，减小系统支承角，，可抑制系统的加速度响应幅值，扩大破损边界的安全区域；在低频率比处，增加质量比可抑制易损件加速度响应峰值；考虑阻尼条件下，增加易损件与主体连接部阻尼、主体与基础连接部阻尼，可降低易损件加速度响应峰值、扩大破损边界安全区域；系统频率比是设计中关注的重要参数，在允许条件下应尽可能增加系统频率比。
[Abstract]:Since the 1990s, Toyota has exhibited spring shock absorbers (oblique support vibration absorbers) at the Beijing International Automobile and Technology equipment Exhibition, which has received extensive attention in various engineering fields. The oblique support packaging system is an improved buffer packaging system which is connected by four elastic buffer elements to the bottom of the inner box and the outer box. It uses the geometric nonlinearity of the inclined mounting spring to protect the engine against vibration. The damping effect is better than that of the linear system with vertical spring suspension. It is generally used in precision instruments with low brittleness and in the protection of the equipment. In the process of logistics transportation, the breakage of the product first occurs in one or several fragile parts, that is, the vulnerable parts, so it is closer to the reality to treat the product as a nonlinear buffer system with two degrees of freedom geometric structure. Based on numerical analysis, Newton's second law and product damage evaluation, the dynamic characteristics of the system are studied. The main contents are as follows: firstly, the dynamic model of the system is established. According to Newton's second law, the dynamic equation of two degrees of freedom of the system is established, and the vibration dynamic equation and the shock dynamic equation of the system are obtained by Taylor series expansion, and the dimensionless treatment is carried out. Secondly, the natural vibration characteristics of the system are studied. Based on the fourth order Runge-Kutta numerical analysis method, the vibration dynamic equations are solved, and the displacement and acceleration responses of the vulnerable parts of the system are obtained. The supporting angle of the system, the frequency ratio of the system, and the mass ratio of the system are analyzed. The influence of the main body's dimensionless initial displacement on the displacement and acceleration response of the damaged parts. The results show that with the increase of the frequency ratio of the system and the decrease of the main body dimensionless initial displacement, the peak value of the displacement response of the vulnerable parts decreases significantly, and with the decrease of the supporting angle or the increase of the mass ratio, the peak value of the displacement response of the vulnerable parts decreases slightly and the period prolongs. With the decrease of the support angle, the increase of the frequency ratio, the decrease of the main body's dimensionless initial displacement and the increase of the mass ratio, the peak value of the acceleration response of the vulnerable parts of the system is decreased. Finally, the impact characteristics of the system under rectangular pulse excitation are studied. Based on the fourth-order Runge-Kutta numerical analysis method, the shock dynamic equation is solved, and the acceleration response of the damaged parts is obtained. Combined with the traditional brittle value theory, the shock response spectrum and the damage boundary of the system are obtained. The results show that the acceleration response amplitude of the system can be restrained by reducing the supporting angle of the system, and the safe area of the damaged boundary can be enlarged. At the low frequency ratio, the peak acceleration response of the damaged parts can be suppressed by increasing the mass ratio. Increasing damping between the damaged part and the main part, and the damping between the main part and the base part can reduce the peak acceleration response of the damaged part, enlarge the damaged boundary security area, and the frequency ratio of the system is an important parameter in the design. The system frequency ratio should be increased as much as possible under permitted conditions.
【学位授予单位】：江南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB48

【参考文献】