本文關(guān)鍵詞： 熱楔 Eyring流變模型 剪稀效應(yīng) 廣義粘度 粘壓關(guān)系 滑滾比 微彈流　出處：《青島理工大學(xué)》2016年博士論文　論文類型：學(xué)位論文

【摘要】：熱效應(yīng)、流變效應(yīng)、粗糙度效應(yīng)和時(shí)變效應(yīng)是現(xiàn)代彈性流體動(dòng)力潤(rùn)滑理論中重要的研究?jī)?nèi)容。本學(xué)位論文的目的是圍繞熱流變潤(rùn)滑理論,由單一到復(fù)合,深入厘清各效應(yīng)對(duì)特定工況下潤(rùn)滑油膜摩擦學(xué)行為的影響。本論文先從牛頓流體入手,對(duì)剛性固體光滑表面間的平行間隙內(nèi)的潤(rùn)滑油膜開(kāi)展了溫度分布與熱效應(yīng)對(duì)油膜承載力影響的研究,即對(duì)熱楔承載機(jī)理的研究。分析指出:熱楔包括熱密度楔與熱粘度楔兩個(gè)組成部分,熱密度楔對(duì)承載力的貢獻(xiàn)始終為正但效果很小,起主導(dǎo)作用的則是熱粘度楔。分析進(jìn)一步指出:熱粘度楔效應(yīng)有兩個(gè)來(lái)源,即固體表面的溫度差異和油膜內(nèi)部的溫度梯度。這些結(jié)論豐富了五十多年前由英國(guó)學(xué)者Cameron提出的粘度楔潤(rùn)滑理論。另外,通過(guò)固液界面上不同溫度邊界條件下的數(shù)值解,揭示了在流體動(dòng)力潤(rùn)滑狀態(tài)下幾何楔和熱楔各自對(duì)滑塊軸承承載力的貢獻(xiàn)大小。接下來(lái),面向非牛頓流變模型,明確了廣義粘度的物理意義,重新推導(dǎo)并改進(jìn)了廣義Reynolds方程。對(duì)Eyring流變模型的本構(gòu)方程給出了一個(gè)新的表達(dá)形式,使得數(shù)值求解時(shí)可通過(guò)牛頓粘度和剪應(yīng)變率直接計(jì)算廣義粘度,從而極大提高了流變分析的計(jì)算效率。通過(guò)具體算例及對(duì)尺度效應(yīng)的研究指出,廣義粘度的高低和摩擦系數(shù)的大小是由熱稀效應(yīng)和剪稀流變效應(yīng)共同決定的。剪稀效應(yīng)在重載小滑滾比條件下就會(huì)發(fā)生,而大滑滾比條件下熱稀效應(yīng)更為強(qiáng)烈。使用“同一油品相同的密度對(duì)應(yīng)相同的粘度”的假說(shuō),提出了一個(gè)由密度求粘度的新粘壓關(guān)系式,該關(guān)系式不僅可以與實(shí)驗(yàn)測(cè)得的粘度變化高度吻合,且通過(guò)Dowson-Higginson密度公式可以把Barus粘度、Doolittle粘度以及Roelands粘度在形式上統(tǒng)一起來(lái),從而在更深的層次上揭示了粘度與密度的關(guān)系。新粘度公式被成功應(yīng)用到點(diǎn)接觸Eyring熱彈流潤(rùn)滑分析中,摩擦系數(shù)的數(shù)值解與實(shí)驗(yàn)結(jié)果吻合良好,這不僅驗(yàn)證了新公式的準(zhǔn)確性,也證實(shí)了所用密度和粘度關(guān)系假說(shuō)的合理性。在本論文的最后兩章,按先易后難的順序,把前面關(guān)于穩(wěn)態(tài)潤(rùn)滑問(wèn)題的工作推廣到因粗糙表面的運(yùn)動(dòng)而存在時(shí)變效應(yīng)的點(diǎn)接觸Eyring非牛頓流體的熱彈流數(shù)值仿真之中。先分析了高速滾滑條件下固體材料的熱導(dǎo)率、滑滾比的大小和正負(fù)、單個(gè)橫向粗糙峰谷的相對(duì)位置等對(duì)接觸區(qū)壓力、膜厚、溫度、流變行為及摩擦力的影響,接著探討了兩固體表面各有一列粗糙峰時(shí)粗糙輪廓之間相互作用的規(guī)律,揭示了粗糙度波長(zhǎng)和接觸固體尺度等參數(shù)與摩擦系數(shù)的關(guān)聯(lián),從而豐富了微彈流潤(rùn)滑的知識(shí)體系。這無(wú)論在學(xué)術(shù)上,還是對(duì)工程設(shè)計(jì)都有一定的參考價(jià)值。
[Abstract]:Thermal effect, rheological effect, roughness effect and time-varying effect are important research contents in modern elastohydrodynamic lubrication theory. The effects of various effects on the tribological behavior of lubricating oil film under specific conditions are thoroughly clarified. This paper begins with Newtonian fluid. The effects of temperature distribution and thermal effect on the bearing capacity of lubricating oil film in parallel gap between smooth surfaces of rigid solids were studied. It is pointed out that the hot wedge consists of thermal wedge and viscosity wedge. The contribution of thermal wedge to bearing capacity is always positive but the effect is very small. The thermal viscosity wedge plays a leading role. The analysis further points out that there are two sources of thermal viscosity wedge effect. These conclusions enrich the viscosity wedge lubrication theory put forward by British scholar Cameron more than 50 years ago. The contribution of geometric wedge and hot wedge to bearing bearing capacity under hydrodynamic lubrication is revealed by numerical solution under different temperature boundary conditions at solid-liquid interface. Next, non-Newtonian rheological model is introduced. The physical meaning of generalized viscosity is clarified, the generalized Reynolds equation is rederived and improved, and a new expression of constitutive equation of Eyring rheological model is given. The generalized viscosity can be directly calculated by Newtonian viscosity and shear strain rate, which greatly improves the computational efficiency of rheological analysis. The generalized viscosity and the friction coefficient are determined by the thermal dilute effect and the shear-dilute rheological effect. The thermal thinning effect is stronger under the condition of large slip ratio. Using the hypothesis that "the same density of the same oil corresponds to the same viscosity", a new visco-pressure relation is proposed, in which the viscosity is calculated by the density. The formula can not only accord with the viscosity measured by experiment, but also can be used to calculate the viscosity of Barus by Dowson-Higginson density formula. Doolittle viscosity and Roelands viscosity are unified in form. The new viscosity formula has been successfully applied to point contact Eyring thermal elastohydrodynamic lubrication analysis. The numerical solution of friction coefficient is in good agreement with the experimental results. This not only verifies the accuracy of the new formula, but also verifies the rationality of the hypothesis of density and viscosity. The previous work on steady state lubrication is extended to the thermal elastohydrodynamic simulation of point contact Eyring non-Newtonian fluid with time-varying effect due to the motion of rough surface. Firstly, the solid is analyzed under the condition of high speed rolling and sliding. Thermal conductivity of bulk materials. The influence of the ratio of slip to roll, the relative position of a single transverse rough peak and valley on the contact pressure, film thickness, temperature, rheological behavior and friction force. Then, the interaction of rough profiles with a series of rough peaks on two solid surfaces is discussed, and the correlation between the parameters such as roughness wavelength, contact solid scale and friction coefficient is revealed. It enriches the knowledge system of micro elastohydrodynamic lubrication, which has certain reference value in both academic and engineering design.
【學(xué)位授予單位】：青島理工大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：TH117.2

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