發(fā)布時(shí)間：2018-02-22 08:57

  本文關(guān)鍵詞： 壓電主動(dòng)傳感 分形理論 時(shí)間反演法 螺栓預(yù)緊力 頻率跟蹤　出處：《武漢科技大學(xué)》2016年博士論文　論文類(lèi)型：學(xué)位論文

【摘要】：螺栓聯(lián)接廣泛應(yīng)用于機(jī)械、化工、交通、電力、航空、土木等行業(yè)的各類(lèi)設(shè)備和結(jié)構(gòu)中,一方面用于聯(lián)接可拆卸部件,另一方面在很多情況下也用于傳遞零部件間的載荷,其聯(lián)接狀態(tài)(表現(xiàn)為軸向預(yù)緊力)直接關(guān)系到整個(gè)設(shè)備或結(jié)構(gòu)工作的可靠性和安全性。因此對(duì)螺栓的聯(lián)接狀態(tài)進(jìn)行實(shí)時(shí)有效地監(jiān)測(cè),對(duì)于保障結(jié)構(gòu)安全、避免重大安全事故具有重大意義和應(yīng)用價(jià)值。論文根據(jù)對(duì)超聲波在螺栓聯(lián)接界面?zhèn)鞑ヌ匦缘姆治?揭示了超聲波能量在螺栓聯(lián)接界面的傳遞機(jī)理;通過(guò)對(duì)螺栓聯(lián)接界面表面微觀特征分形和接觸特性的研究,確立了螺栓聯(lián)接界面實(shí)際接觸面積與預(yù)緊力之間的關(guān)系;基于壓電主動(dòng)傳感的方式,采用能量法、時(shí)間反演法和頻率跟蹤法對(duì)螺栓聯(lián)接狀態(tài)監(jiān)測(cè)進(jìn)行了研究。論文所做的主要工作如下:(1)螺栓聯(lián)接界面表面微觀特性與接觸研究考察了分形參數(shù)對(duì)傳統(tǒng)粗糙度參數(shù)的影響,探討了分形維數(shù)與傳統(tǒng)粗糙度參數(shù)存在的聯(lián)系,證實(shí)分形維數(shù)可以用來(lái)表征工程粗糙面的粗糙程度。從接觸點(diǎn)(即微凸體)的彈性變形、彈塑性變形及全塑形變形出發(fā),建立了螺栓聯(lián)接界面實(shí)際接觸面積分形模型。隨著接觸總載荷的增加,實(shí)際接觸面積也相應(yīng)增加;在相同載荷下,表面越光滑,實(shí)際接觸面積越大。這為揭示超聲波能量在螺栓聯(lián)接界面的傳遞機(jī)理提供了理論基礎(chǔ)。(2)螺栓聯(lián)接界面超聲透射波能量傳遞模型研究利用反射定律和折射定律建立了螺栓聯(lián)接界面超聲透射波能量傳遞模型,該模型表示出超聲透射波能量、實(shí)際接觸面積和預(yù)緊力三者之間的關(guān)系。當(dāng)一個(gè)分形表面與一個(gè)理想平面接觸時(shí),隨著預(yù)緊力的增加,實(shí)際接觸面積增加,接收到的超聲透射波信號(hào)能量也隨之增大。這一結(jié)論揭示了超聲波能量在螺栓聯(lián)接界面的傳遞機(jī)理。(3)基于能量法的螺栓聯(lián)接狀態(tài)監(jiān)測(cè)研究超聲透射波響應(yīng)信號(hào)能量與預(yù)緊扭矩有較好的相關(guān)性,但螺栓聯(lián)接界面表面粗糙度對(duì)響應(yīng)信號(hào)能量變化趨勢(shì)有影響。能量法不用考慮螺栓聯(lián)接結(jié)構(gòu)的具體特征參數(shù)值,也不用考慮壓電材料的具體規(guī)格,具有較好的實(shí)際應(yīng)用意義,適用于設(shè)備底座及鋼結(jié)構(gòu)等接觸表面粗糙度較大的螺栓聯(lián)接狀態(tài)監(jiān)測(cè)。(4)基于時(shí)間反演法的螺栓聯(lián)接狀態(tài)監(jiān)測(cè)研究時(shí)間反演的聚焦信號(hào)峰值(即信號(hào)能量)與螺栓預(yù)緊力有較好的單調(diào)變化關(guān)系,通過(guò)分析信號(hào)峰值能夠確定螺栓聯(lián)接狀態(tài)。與直接測(cè)量響應(yīng)信號(hào)相比,聚焦信號(hào)信噪比高,抗干擾能力強(qiáng)。時(shí)間反演法可以作為螺栓聯(lián)接狀態(tài)監(jiān)測(cè)的一種有效手段。(5)基于頻率跟蹤法的螺栓聯(lián)接狀態(tài)監(jiān)測(cè)研究基于分形理論建立了螺栓聯(lián)接界面法向接觸剛度模型,探討了螺栓預(yù)緊力、聯(lián)接界面法向接觸剛度和模態(tài)頻率之間的聯(lián)系。當(dāng)螺栓預(yù)緊力增加時(shí),法向接觸剛度增加,螺栓聯(lián)接結(jié)構(gòu)的模態(tài)頻率也隨之增加。實(shí)驗(yàn)研究表明,頻率跟蹤法避開(kāi)了螺栓聯(lián)接界面實(shí)際接觸面積、接觸剛度、結(jié)構(gòu)各階模態(tài)頻率等的復(fù)雜計(jì)算過(guò)程,無(wú)需考慮壓電材料規(guī)格的具體參數(shù)值,能跟蹤螺栓聯(lián)接結(jié)構(gòu)某階模態(tài)頻率隨預(yù)緊力的變化趨勢(shì)。(6)提出一種基于宏觀接觸面可控的壓電主動(dòng)式螺栓預(yù)緊力監(jiān)測(cè)方法螺栓聯(lián)接界面表面粗糙度對(duì)以上幾種監(jiān)測(cè)方法的監(jiān)測(cè)范圍都有影響,當(dāng)接觸界面粗糙度值較小時(shí),隨著預(yù)緊力增加,信號(hào)很快趨于飽和,限制了預(yù)緊力監(jiān)測(cè)范圍。鑒于此,提出了一種采用凹凸面接觸型式的螺栓預(yù)緊力監(jiān)測(cè)方法,該方法測(cè)量范圍廣、抗噪性能好,能實(shí)現(xiàn)對(duì)螺栓預(yù)緊力的在線監(jiān)測(cè),在螺栓聯(lián)接狀態(tài)監(jiān)測(cè)上具有很好的應(yīng)用前景。
[Abstract]:Bolt is widely used in mechanical, chemical, transportation, electric power, aviation, various types of equipment and structures of civil industry, on the one hand is used for connecting removable parts, on the other hand, in many cases is also used to transfer load between parts, the connection state (as axial preload) is directly related to the reliability and the safety of the equipment or construction work. So the connection state of the bolt are effectively in real time monitoring, to ensure the safety of the structure, to avoid major accidents is of great significance and application value. Based on the analysis of the connection interface propagation characteristics of ultrasonic wave in bolt, reveals the ultrasonic energy transfer mechanism at the interface through the bolt connection; Study on the interfacial microstructure and surface fractal contact characteristics of bolt connection, establish the relation between the bolt connection interface to the actual contact area and the pretightening force based on piezoelectric; Active sensing method using energy method of bolt connection monitoring frequency tracking and time reversal method. The main contents are as follows: (1) the microscopic characteristics of bolt connection interface surface and contact study examined the influence of fractal parameters on the traditional roughness parameters are discussed, and the fractal dimension the traditional roughness parameters, confirmed that the fractal dimension can be used to characterize the engineering rough surface roughness. From the point of contact (i.e. asperity) elastic deformation, elastic-plastic deformation and plastic deformation of a bolt connection interface of the actual contact area. With the increase of the contact fractal model of total load, the actual contact area also increase; under the same load, the surface is smooth, the actual contact area larger. This provides a theoretical basis for revealing the ultrasonic energy in the bolt interface transfer mechanism (2) bolts. The interface of ultrasonic wave energy transfer model based on the laws of reflection and refraction a bolt connection interface ultrasonic transmission wave energy transfer model, this model expresses the ultrasonic wave energy, the relationship between the actual contact area and the pretightening force of the three. When a fractal surface and an ideal plane contact, with the increase of the preload, the actual contact area increases, the energy of ultrasonic transmission received signal increases. This conclusion reveals the ultrasonic energy transfer mechanism in the bolt interface. (3) the connection bolt energy method for condition monitoring of the ultrasonic wave response signal energy and torque have a good correlation based on but, the bolt connection interface of surface roughness on the response signal energy variation trend. The energy method not value the specific parameters of bolt connection structure into account, also need not consider piezoelectric The size of the material, and has better practical significance for equipment base and steel structure contact surface roughness of bolt connection monitoring greatly. (4) the focusing signal peak bolt connection state monitoring of time reversal method based on time reversal (i.e. signal energy) have good monotonic relation with bolt the pretightening force, through the analysis of peak signal to determine the bolt connection state. Compared with the direct measurement of the response signal, the focusing signal with high signal-to-noise ratio, strong anti-interference ability. An effective method of time reversal method can be used as a bolt connection state monitoring. (5) frequency tracking method based on condition monitoring of bolt connection based on Fractal theory is established the bolt connection interface contact stiffness model of bolt preload, contact connection between interfacial normal contact stiffness and modal frequency. When the increase of bolt preload when And the normal contact stiffness increases, the modal frequency of bolt joint structure is also increased. Experimental results show that the frequency tracking method to avoid the bolt connection interface to the actual contact area, contact stiffness, the complicated calculation process of each mode frequency, without the value of specific parameters of piezoelectric material specifications into account, can change trend track bolt connection structure of a modal frequency with preload. (6) the effect of piezoelectric active bolt preload monitoring method of bolt connection interface surface based on a macroscopic contact surface roughness on the controllable monitoring method of several monitoring range, when the interface roughness is small, with the the increase of the pre tightening force, signal quickly become saturated, limiting the preload of the monitoring range. In view of this, put forward a concave convex contact type bolt preload monitoring method, the method of wide measurement range, anti noise performance Well, the on-line monitoring of bolt pre tightening force can be realized, and it has a good application prospect in the monitoring of bolt connection state.

【學(xué)位授予單位】：武漢科技大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類(lèi)號(hào)】：TH131.3;TP274

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