發(fā)布時間：2018-08-07 16:27

【摘要】：豐田汽車自二十世紀九十年代在北京國際汽車及工藝裝備展覽會上展出了彈簧減震器（斜支承減振系統(tǒng)），受到各工程領域的廣泛關注。斜支承包裝系統(tǒng)是由四個彈性緩沖元件將內(nèi)箱體與外箱體底部連接在一起的一種結構改進緩沖包裝系統(tǒng)，利用傾斜安裝彈簧的幾何非線性對發(fā)動機進行減振保護，其減振效果優(yōu)于彈簧垂直懸掛的線性系統(tǒng)，一般應用于脆值較低的精密儀器、設備的減振保護。在物流運輸過程中，產(chǎn)品的破損首先發(fā)生在某個或某幾個脆弱部件，即易損件，將產(chǎn)品處理為二自由度幾何結構非線性緩沖系統(tǒng)更貼近實際。 針對考慮易損件的斜支承包裝系統(tǒng)為研究對象，基于數(shù)值分析、牛頓第二定律及產(chǎn)品破損評價等理論方法，研究系統(tǒng)的動力學特性。主要內(nèi)容如下： 首先，建立系統(tǒng)的動力學模型。根據(jù)牛頓第二定律，建立系統(tǒng)二自由度動力學方程，應用泰勒級數(shù)展開進行簡化處理，得到系統(tǒng)振動動力學方程和沖擊動力學方程并進行無量綱化處理。 其次，研究系統(tǒng)的自振特性�；�于四階龍格-庫塔數(shù)值分析方法，求解振動動力學方程，得到系統(tǒng)易損件的位移響應和加速度響應，分析系統(tǒng)支承角、系統(tǒng)頻率比、系統(tǒng)質(zhì)量比、主體無量綱初始位移等對易損件位移、加速度響應的影響規(guī)律。結果表明，增加系統(tǒng)頻率比、減小主體無量綱初始位移，易損件的位移響應峰值顯著降低；隨支承角度的減小或質(zhì)量比的增加，易損件的位移響應峰值略有下降且周期延長；隨系統(tǒng)支承角的減小、頻率比的增加、主體無量綱初始位移的減小、質(zhì)量比的增加，系統(tǒng)易損件的加速度響應峰值降低。 最后，研究系統(tǒng)在矩形脈沖激勵下的沖擊特性。基于四階龍格-庫塔數(shù)值分析方法，求解沖擊動力學方程，得到易損件加速度響應，并結合傳統(tǒng)脆值理論，得到系統(tǒng)易損件的沖擊響應譜和破損邊界。結果表明，減小系統(tǒng)支承角，，可抑制系統(tǒng)的加速度響應幅值，擴大破損邊界的安全區(qū)域；在低頻率比處，增加質(zhì)量比可抑制易損件加速度響應峰值；考慮阻尼條件下，增加易損件與主體連接部阻尼、主體與基礎連接部阻尼，可降低易損件加速度響應峰值、擴大破損邊界安全區(qū)域；系統(tǒng)頻率比是設計中關注的重要參數(shù)，在允許條件下應盡可能增加系統(tǒng)頻率比。
[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.
【學位授予單位】：江南大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TB48

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