本文選題：沖擊 + 應(yīng)力波��； 參考：《哈爾濱工業(yè)大學(xué)》2015年碩士論文

【摘要】：沖擊機(jī)械由于利用撞擊而能產(chǎn)生強(qiáng)度極大的力流,與相同功率下的靜壓機(jī)械相比,其結(jié)構(gòu)更為緊湊,在工業(yè)生產(chǎn)中有著廣泛的應(yīng)用并有著相似的動(dòng)作原理:即沖錘部件在重力、液壓、或蒸汽等力的作用下加速運(yùn)動(dòng),并以一定的速度撞擊工作對(duì)象,使得工作對(duì)象發(fā)生位移、變形和破壞。傳統(tǒng)機(jī)械動(dòng)力學(xué)分析將機(jī)械零部件作為剛體或質(zhì)點(diǎn),忽略了介質(zhì)微單元體的慣性。波動(dòng)力學(xué)理論考慮了以毫秒甚至納秒計(jì)短暫時(shí)間尺度上發(fā)生的運(yùn)動(dòng)參量顯著變化,是沖擊機(jī)械系統(tǒng)能量傳遞過程分析所必須依賴的力學(xué)基礎(chǔ)。受空間環(huán)境下月壤采樣機(jī)構(gòu)能源供給的限制,本文立足于一般化的沖擊機(jī)械模型,在假定巖土動(dòng)態(tài)加載剛度一定的條件下分析比較了不同入射波形對(duì)巖土介質(zhì)作功過程中能量傳遞效率情況;以實(shí)現(xiàn)最優(yōu)指數(shù)應(yīng)力波形為目標(biāo),基于一維波動(dòng)力學(xué)理論并使用?函數(shù)法對(duì)沖錘部件的波阻抗進(jìn)行反演設(shè)計(jì);使用正解計(jì)算和有限元仿真的方法驗(yàn)證反演設(shè)計(jì)的正確性;首次提出假設(shè)脫離法,基于線性疊加原理,分析了沖錘與擊桿間的受力及運(yùn)動(dòng)狀態(tài),分析了沖錘幾何外形無量綱參數(shù)影響下能量傳遞效率和沖錘沖擊效率的變化規(guī)律并計(jì)算相關(guān)的最優(yōu)參數(shù)。入射波在變波阻抗或是變截面桿形部件傳播過程中必然會(huì)有反射波的產(chǎn)生。本文以應(yīng)力波在變波阻抗桿形部件的透反射規(guī)律為研究對(duì)象,利用頻域分析法及有限元程序,在擊桿兩端波阻抗比值給定且一端受到?jīng)_擊載荷的情況下對(duì)不同波阻抗方案的能量透射效率給予分析與比較;使用泛函極值問題的變分法,兼顧能量透射效率,求解得到反對(duì)稱波阻抗條件下使擊桿部件具有質(zhì)量最小的平原式幾何方案;比較分析了該方案相對(duì)于其他方案的優(yōu)勢(shì),有利于實(shí)際工程應(yīng)用。將提高系統(tǒng)工作效率的相關(guān)措施應(yīng)用在以空心為幾何特征的月壤采樣機(jī)構(gòu)設(shè)計(jì)中。結(jié)合有限元仿真程序,對(duì)比優(yōu)化設(shè)計(jì)前后的仿真結(jié)果,驗(yàn)證了文中理論研究所得到的優(yōu)化設(shè)計(jì)方案可有效提高系統(tǒng)的工作效率。
[Abstract]:The impact machine can produce a strong force flow by using the impact. Compared with the static pressure machine with the same power, its structure is more compact, and it is widely used in industrial production and has similar action principle: namely, the impact hammer parts are in gravity.Under the action of hydraulic pressure or steam equal force accelerates motion and impinges the working object at a certain speed which causes displacement deformation and destruction of the working object.In the traditional mechanical dynamic analysis, the mechanical parts are regarded as rigid body or particle, and the inertia of dielectric microelement is ignored.The theory of wave mechanics takes into account the significant changes of motion parameters in millisecond or even nanosecond time-scales, which is the mechanical basis on which the analysis of energy transfer process of impact mechanical system depends.Limited by the energy supply of lunar soil sampling mechanism in the space environment, this paper is based on the general impact mechanical model.Under the assumption that the dynamic loading stiffness of rock and soil is constant, the energy transfer efficiency of different incident waveforms in the process of doing work on geotechnical medium is analyzed and compared, with the goal of realizing the optimal exponential stress waveform, based on the theory of one-dimensional wave mechanics and using?The function method is used to counter the wave impedance of hammer components for inversion design; the forward solution calculation and finite element simulation are used to verify the correctness of the inversion design; the hypothesis separation method is proposed for the first time, which is based on the principle of linear superposition.The force and motion state between impact hammer and hammer are analyzed. The energy transfer efficiency and impact efficiency of impact hammer under the influence of dimensionless parameters of impact hammer geometry are analyzed and the optimal parameters are calculated.The incident wave is bound to produce reflected waves during the propagation of variable impedance or rod-shaped parts with variable cross-section.In this paper, we take the law of the stress wave reflected in the variable wave impedance bar as the research object, and use the frequency domain analysis method and the finite element program.The energy transmission efficiency of different wave impedance schemes is analyzed and compared under the condition that the ratio of wave impedance at both ends of the rod is given and one end is subjected to impact load, and the energy transmission efficiency is taken into account by using the variational method of functional extremum problem.The plain geometry scheme with minimum mass of the hammer member is obtained under the condition of antisymmetric wave impedance, and the advantages of the scheme compared with other schemes are compared and analyzed, which is beneficial to practical engineering application.The related measures to improve the working efficiency of the system are applied to the design of the lunar soil sampling mechanism with hollow geometry.Combining with the finite element simulation program, the simulation results before and after the optimization design are compared, and it is verified that the optimal design scheme obtained in this paper can effectively improve the working efficiency of the system.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P184.5

【參考文獻(xiàn)】

相關(guān)期刊論文 前2條

1 丁問司;丁元文;范亞軍;;交變氣動(dòng)沖擊錘瞬態(tài)沖擊特性分析[J];機(jī)械工程學(xué)報(bào);2015年03期

2 牛雷雷;朱萬(wàn)成;李少華;李帥;于淼;;擺錘沖擊加載下砂巖中應(yīng)變率動(dòng)力特性的試驗(yàn)研究[J];巖石力學(xué)與工程學(xué)報(bào);2014年12期

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本文編號(hào)：1756433