【摘要】：磁流變液是一種新型的智能材料,在無磁場的情況下表現(xiàn)為低粘度的牛頓液體特性,一旦加入磁場,便會在毫秒級時間內(nèi)響應(yīng)變?yōu)楣腆w或者類固體狀態(tài),這種特性被稱為磁流變效應(yīng)。目前的眾多磁流變液產(chǎn)品一般都是對磁流變液的力學(xué)特性的應(yīng)用,因此磁流變液的力學(xué)性能研究也是磁流變液研究工作的一個重要方面。在磁流變液眾多力學(xué)特性應(yīng)用中,當(dāng)屬剪切應(yīng)力特性應(yīng)用最為廣泛,因此磁流變液的流變特性研究也集中于此。磁流變液剪切應(yīng)力特性輸出一般受到磁場、溫度場、重力場、剪切速率、剪切應(yīng)力方向、導(dǎo)磁性顆粒的大小形狀與分散情況、工作時間、裝置結(jié)構(gòu)與材料特性、工作面表面粗糙度與紋路等眾多因素影響。其中磁場是磁流變液磁流變效應(yīng)的必備因素,而磁流變液實(shí)際工作過程中會有大量的機(jī)械能轉(zhuǎn)化為內(nèi)能從而引起磁流變液的溫升,或者溫度場的不均勻分布。因此,磁場和溫度場變化在磁流變液影響因素中最為突出,而磁流變液實(shí)際工作一般都處于在磁場、溫度相互耦合的環(huán)境之中。本文對磁流變液及影響其力學(xué)特性輸出的主要因素作了簡要介紹,并從磁場、溫度場這兩個影響因素角度,綜述了磁流變液剪切應(yīng)力特性理論研究進(jìn)展和磁流變液流變特性檢測技術(shù)的現(xiàn)狀和發(fā)展趨勢,分析和比較了現(xiàn)有流變特性理論和檢測方法的優(yōu)勢以及不足之處,針對復(fù)合場下磁流變液的特點(diǎn),并提出了本文的研究目的、研究方法、研究意義。文章根據(jù)磁流變液試驗(yàn)裝置設(shè)計和材料性能的檢測需要,介紹了Bingham模型、Bingham雙塑性模型、Herschel-Bulkley模型和Eyring本構(gòu)模型來描述磁流變液流變學(xué)特性理論。經(jīng)過分析和比較,選取了參數(shù)較少,物理意義較為明確的bingham模型作為復(fù)合場內(nèi)磁流變液流變特性理論模型建立的基礎(chǔ)。并從磁流變液的工作模式出發(fā),介紹了管道流動式剪切模型、圓盤剪切模型、圓筒剪切模型,比較選擇了圓筒剪切模型作為實(shí)驗(yàn)裝置的力學(xué)模型基礎(chǔ)。通過有限元分析法,對圓筒剪切模型中磁流變液微元進(jìn)行了受力分析,得到了磁流變液微元的力學(xué)模型,進(jìn)而分析得到了圓筒剪切模型中磁流變液的力學(xué)和運(yùn)動學(xué)規(guī)律。最終總結(jié)得到了圓筒剪切模型中磁流變液剪切應(yīng)力和剪切速率的測量方法,并有效得避免了預(yù)屈服區(qū)間對磁流變液檢測的影響。從復(fù)合場的角度出發(fā),對磁流變液工作過程中磁場和溫度場兩個場復(fù)合作用對磁流變液剪切應(yīng)力輸出特性的影響規(guī)律進(jìn)行了理論分析,以bingham模型、粘溫特性、居里公式、磁流變液磁場強(qiáng)度與流變特性變化規(guī)律四個方面為基礎(chǔ)進(jìn)行理論推導(dǎo),得到了復(fù)合場內(nèi)磁流變液應(yīng)力輸出理論模型。經(jīng)過理論分析發(fā)現(xiàn)溫度場對磁流變液的影響的本質(zhì)乃是改變了磁流變液中軟磁性顆粒的導(dǎo)磁率和載液的粘度,進(jìn)而改變了磁場強(qiáng)度,導(dǎo)致應(yīng)力輸出改變。以圓筒剪切模型、磁場理論分析、溫度場理論分析為基礎(chǔ)設(shè)計并研制了一套復(fù)合場下磁流變液流變特性研究裝置,并通過ansys仿真分析,對裝置的內(nèi)磁流變液的溫度場及磁場分布規(guī)律進(jìn)行了仿真模擬。仿真證明了實(shí)驗(yàn)裝置能夠很好的為磁流變液剪切應(yīng)力特性檢測提供均勻穩(wěn)定的磁場和溫度場,復(fù)合實(shí)驗(yàn)需求。設(shè)計了磁場和剪切速率影響實(shí)驗(yàn)測量、磁場和溫度場復(fù)合實(shí)驗(yàn)測量過程兩個實(shí)驗(yàn),測量了大量的實(shí)驗(yàn)數(shù)據(jù)。從實(shí)驗(yàn)的角度對磁流變液剪切工作過程中溫度場、磁場復(fù)合影響規(guī)律進(jìn)行了研究。數(shù)據(jù)分析發(fā)現(xiàn),磁流變液剪切應(yīng)力輸出隨著磁場、剪切速率上升而上升,隨著溫度場的上升而下降。相比較而言,磁場強(qiáng)度的上升對應(yīng)力輸出的影響要遠(yuǎn)大于剪切速率上升的影響。研究還發(fā)現(xiàn),磁場強(qiáng)度越大的情況下,剪切應(yīng)力隨著溫度場上升而下降的量越大。這與磁場越大時,溫度上升對磁場影響越大的規(guī)律相一致。實(shí)驗(yàn)數(shù)據(jù)分析表明,將溫度場的影響通過居里公式、粘溫特性公式轉(zhuǎn)化為磁場和粘度影響的理論與實(shí)際相吻合,證明了理論推導(dǎo)的正確性。以磁場和溫度場理論模型為基礎(chǔ),設(shè)計了溫度場補(bǔ)償實(shí)驗(yàn)。通過磁場的微量上升補(bǔ)償溫度場上升帶來的磁流變液剪切應(yīng)力下降影響。通過實(shí)驗(yàn)發(fā)現(xiàn),磁流變液剪切應(yīng)力下降量由原來的30%/100℃降低至3%/100℃,基本降到了可接受范圍內(nèi),也進(jìn)一步證明了磁場溫度復(fù)合場對磁流變液影響理論的正確性。
[Abstract]:The magneto-rheological fluid is a new type of intelligent material, which exhibits a Newtonian liquid characteristic of low viscosity in the absence of a magnetic field. Once the magnetic field is added, the response becomes a solid or solid state in the millisecond time, which is referred to as the magneto-rheological effect. At present, a large number of magneto-rheological fluid products are generally applied to the mechanical properties of the magneto-rheological fluid, so that the mechanical property research of the magneto-rheological fluid is also an important aspect of the research of the magneto-rheological fluid. In that application of a plurality of mechanical properties of the magneto-rheological fluid, the application of the shear stress characteristic is the most widely used, and therefore, the rheological property of the magneto-rheological fluid is also concentrated. The output of the shear stress characteristic of the magneto-rheological fluid is generally influenced by the magnetic field, the temperature field, the gravity field, the shear rate, the shear stress direction, the size and shape and the dispersion condition of the magnetic conductive particles, the working time, the device structure and the material property, the surface roughness and the grain of the working surface, and the like. In which the magnetic field is a necessary factor of the magneto-rheological effect of the magneto-rheological fluid, and a large amount of mechanical energy is converted into internal energy in the actual working process of the magneto-rheological fluid so as to cause the temperature rise of the magneto-rheological fluid or the non-uniform distribution of the temperature field. Therefore, the change of the magnetic field and the temperature field is the most prominent in the influence factors of the magneto-rheological fluid, and the actual operation of the magneto-rheological fluid is generally in the environment in which the magnetic field and the temperature are coupled with each other. In this paper, the main factors that influence the output of the magneto-rheological fluid and its mechanical properties are briefly introduced, and the research progress of the shear stress characteristic of the magneto-rheological fluid and the current situation and development trend of the rheological property detection technology of the magneto-rheological fluid are summarized from the aspects of the magnetic field and the temperature field. In this paper, the advantages and disadvantages of the current rheological property theory and the detection method are analyzed and compared, and the characteristics of the magnetorheological fluid under the compound field are analyzed and compared, and the research purpose, the research method and the research significance of the present invention are put forward. According to the design of the magneto-rheological fluid test device and the detection of the material property, the theory of the rheological property of the magneto-rheological fluid is described by the Bingham model, the Bingham double-plastic model, the Herschel-Bulkley model and the Eyring constitutive model. Through the analysis and comparison, the bigham model with less parameters and more physical meaning is selected as the basis of the theoretical model of the rheological property of the magneto-rheological fluid in the composite field. Based on the working mode of the magneto-rheological fluid, the flow-type shear model, the disk shear model and the cylinder shear model are introduced, and the cylinder shear model is selected as the mechanical model base of the experimental device. The mechanical and kinematic law of the magneto-rheological fluid in the cylinder shear model is obtained by means of the finite element analysis method, and the mechanical model of the magnetorheological fluid micro-element is obtained by the force analysis of the magnetorheological fluid micro-element in the cylindrical shear model. In the end, the shear stress and shear rate of the magnetorheological fluid in the cylinder shear model are measured, and the influence of the pre-yield interval on the detection of the magneto-rheological fluid is effectively avoided. From the angle of the compound field, the influence of the magnetic field and the temperature field on the output characteristic of the magneto-rheological fluid in the working process of the magneto-rheological fluid is theoretically analyzed, and the Bingham model, the viscosity-temperature characteristic and the Curie formula are analyzed. Based on the four aspects of the change of the magnetic field strength and the rheological property of the magneto-rheological fluid, the theoretical model of the stress output of the magneto-rheological fluid in the composite field is obtained. It is found that the effect of the temperature field on the magneto-rheological fluid is the change of the permeability of the soft magnetic particles and the viscosity of the carrier liquid in the magneto-rheological fluid, and then the magnetic field strength is changed, resulting in a change of the stress output. Based on the analysis of the cylinder shear model, the magnetic field theory and the temperature field theory, the rheological property of the magneto-rheological fluid under the complex field is developed and the simulation of the temperature field and the distribution of the magnetic field is simulated by the ansys simulation. The simulation proves that the experimental device can provide a uniform and stable magnetic field and temperature field for the detection of the shear stress of the magneto-rheological fluid and the composite experimental requirement. The effects of magnetic field and shear rate on the experimental measurement, magnetic field and temperature field are designed. The influence of temperature field and magnetic field on the process of shear operation of the magneto-rheological fluid is studied from the experimental point of view. The data analysis shows that the shear stress of the magneto-rheological fluid increases with the magnetic field and the shear rate, and decreases with the rise of the temperature field. In contrast, the effect of the rise of the magnetic field strength on the stress output is much greater than the shear rate increase. It has also been found that the larger the magnetic field strength, the more the shear stress decreases as the temperature field increases. The larger the magnetic field, the greater the influence of the temperature rise on the magnetic field. The experimental data analysis shows that the influence of the temperature field through the Curie formula and the viscosity-temperature characteristic formula is the theoretical and practical coincidence of the influence of the magnetic field and the viscosity, and the correctness of the theoretical deduction is proved. The temperature field compensation experiment is designed based on the theoretical model of the magnetic field and the temperature field. The decrease of the shear stress of the magneto-rheological fluid due to the rise of the temperature field is compensated by the increase of the magnetic field. The experimental results show that the decrease of the shear stress of the magneto-rheological fluid is reduced from 30%/100 鈩，

本文編號：2435186