基于压电主动传感的螺栓联接状态监测机理与方法研究

发布时间：2018-02-22 08:57

本文关键词： 压电主动传感分形理论时间反演法螺栓预紧力频率跟踪　出处：《武汉科技大学》2016年博士论文　论文类型：学位论文

【摘要】：螺栓联接广泛应用于机械、化工、交通、电力、航空、土木等行业的各类设备和结构中,一方面用于联接可拆卸部件,另一方面在很多情况下也用于传递零部件间的载荷,其联接状态(表现为轴向预紧力)直接关系到整个设备或结构工作的可靠性和安全性。因此对螺栓的联接状态进行实时有效地监测,对于保障结构安全、避免重大安全事故具有重大意义和应用价值。论文根据对超声波在螺栓联接界面传播特性的分析,揭示了超声波能量在螺栓联接界面的传递机理;通过对螺栓联接界面表面微观特征分形和接触特性的研究,确立了螺栓联接界面实际接触面积与预紧力之间的关系;基于压电主动传感的方式,采用能量法、时间反演法和频率跟踪法对螺栓联接状态监测进行了研究。论文所做的主要工作如下:(1)螺栓联接界面表面微观特性与接触研究考察了分形参数对传统粗糙度参数的影响,探讨了分形维数与传统粗糙度参数存在的联系,证实分形维数可以用来表征工程粗糙面的粗糙程度。从接触点(即微凸体)的弹性变形、弹塑性变形及全塑形变形出发,建立了螺栓联接界面实际接触面积分形模型。随着接触总载荷的增加,实际接触面积也相应增加;在相同载荷下,表面越光滑,实际接触面积越大。这为揭示超声波能量在螺栓联接界面的传递机理提供了理论基础。(2)螺栓联接界面超声透射波能量传递模型研究利用反射定律和折射定律建立了螺栓联接界面超声透射波能量传递模型,该模型表示出超声透射波能量、实际接触面积和预紧力三者之间的关系。当一个分形表面与一个理想平面接触时,随着预紧力的增加,实际接触面积增加,接收到的超声透射波信号能量也随之增大。这一结论揭示了超声波能量在螺栓联接界面的传递机理。(3)基于能量法的螺栓联接状态监测研究超声透射波响应信号能量与预紧扭矩有较好的相关性,但螺栓联接界面表面粗糙度对响应信号能量变化趋势有影响。能量法不用考虑螺栓联接结构的具体特征参数值,也不用考虑压电材料的具体规格,具有较好的实际应用意义,适用于设备底座及钢结构等接触表面粗糙度较大的螺栓联接状态监测。(4)基于时间反演法的螺栓联接状态监测研究时间反演的聚焦信号峰值(即信号能量)与螺栓预紧力有较好的单调变化关系,通过分析信号峰值能够确定螺栓联接状态。与直接测量响应信号相比,聚焦信号信噪比高,抗干扰能力强。时间反演法可以作为螺栓联接状态监测的一种有效手段。(5)基于频率跟踪法的螺栓联接状态监测研究基于分形理论建立了螺栓联接界面法向接触刚度模型,探讨了螺栓预紧力、联接界面法向接触刚度和模态频率之间的联系。当螺栓预紧力增加时,法向接触刚度增加,螺栓联接结构的模态频率也随之增加。实验研究表明,频率跟踪法避开了螺栓联接界面实际接触面积、接触刚度、结构各阶模态频率等的复杂计算过程,无需考虑压电材料规格的具体参数值,能跟踪螺栓联接结构某阶模态频率随预紧力的变化趋势。(6)提出一种基于宏观接触面可控的压电主动式螺栓预紧力监测方法螺栓联接界面表面粗糙度对以上几种监测方法的监测范围都有影响,当接触界面粗糙度值较小时,随着预紧力增加,信号很快趋于饱和,限制了预紧力监测范围。鉴于此,提出了一种采用凹凸面接触型式的螺栓预紧力监测方法,该方法测量范围广、抗噪性能好,能实现对螺栓预紧力的在线监测,在螺栓联接状态监测上具有很好的应用前景。
[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.

【学位授予单位】：武汉科技大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TH131.3;TP274

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