【作者】 刘阳；

【导师】 张伟； 王欣；

【作者基本信息】 大连理工大学 ， 机械工程（专业学位）， 2021， 硕士

【摘要】 螺栓连接广泛应用于现代机器中,在航空航天行业中,螺栓连接装配的成本可以达到总成本的40%,装配螺栓的工作量大概为整机装配总工作量的一半,螺栓连接的装配质量对整机可靠稳定运行具有重大影响。螺栓连接的特点是通过施加合适的预紧力使整体的结构可以承受较大的载荷,而预紧力的精准控制一直是螺栓装配的难点和重点,影响螺栓拧紧精度的因素众多,包括材料、形状、尺寸、螺栓数量以及排列方式,装配环境等等,而我国的螺栓装配理论在螺栓防松、拧紧工艺的优化等方面有一些研究,但是对于制造误差对于装配质量的影响研究较少;另外缺乏实用性的计算服役阶段螺栓实际承受载荷的方法,因为绝大多数情况下螺栓承受的都是偏心载荷,并且连接结构各不相同,所以难以对螺栓承载传递函数做出统一的计算,国内大多数研究采用有限元仿真分析以及试验的方法针对某一特定结构进行研究,对于影响载荷传递函数因素的研究寥寥无几。针对以上两点问题,本文将结合面制造误差引入到预紧力形成以及接触应力状态变化的过程中,并在此基础上进一步分析了预紧力离散以及其他一些因素对服役阶段螺栓连接结构疲劳性能的影响规律。首先,本文以M10螺栓连接为例,建立了考虑螺距误差下的螺牙啮合理论模型,揭示了应力重分布的产生机理。然后,为了进一步定量的分析变化规律,建立了参数化的有限元单螺栓拧紧仿真模型,通过绘制不同制造误差下的扭矩-预紧力关系曲线,验证了制造误差下预紧力形成机理的正确性,通过对比不同制造误差下的螺栓节点应力分布云图,验证了制造误差对接触面应力重分布理论的正确性,并据此提出了一种改善螺栓承载性能的方法。最后,通过单螺栓拧紧试验建立了螺距误差与螺纹摩擦扭矩、端面摩擦扭矩以及螺栓预紧力的关联关系,验证了仿真模型的合理性以及上述理论的准确性。在以上工作的基础上,本文对螺栓服役阶段实际承受载荷的计算进行了研究,分析了不同阶段螺栓承载的变化,研究了预紧力离散对螺栓承载的影响,并进一步分析了影响螺栓承受载荷的因素,然后通过有限元仿真模型验证影响规律的准确性。本文将结合面制造误差带入到拧紧过程中螺栓预紧力形成过程中,并研究了其对服役过程中螺栓承载的影响,从螺栓拧紧精度和螺栓承载两个状态连续的角度分析了多种因素对螺栓连接疲劳性能的影响规律,对螺栓的装配工艺以及环形法兰螺栓连接结构的设计具有一定的指导意义。更多还原

【Abstract】 Bolted connections are widely used in modern machines.In the aerospace industry,the cost of bolted connection assembly can reach 40% of the total cost.The workload of assembling bolts is about half of the total assembly workload of the whole machine.The assembly quality of bolted connections is right The reliable and stable operation of the whole machine has a major impact.The characteristic of bolt connection is that the overall structure can withstand larger loads by applying appropriate pretension.The precise control of pretension has always been the difficulty and focus of bolt assembly.There are many factors that affect the accuracy of bolt tightening,including materials,Shape,size,number and arrangement of bolts,assembly environment,etc.,while our country’s bolt assembly theory has some research on bolt antiloosening and tightening process optimization,but there are few studies on the impact of manufacturing deviation on assembly quality;in addition,There is no practical method for calculating the actual load of bolts during the service stage.Because the bolts are subjected to eccentric loads in most cases,and the connection structures are different,it is difficult to make a unified calculation of the bolt load transfer function.Most studies use finite element simulation analysis and test methods to study a specific structure,and there are few studies on the factors that affect the load transfer function.In view of the above two problems,this paper introduces the manufacturing deviation of the joint surface into the process of pretension formation and contact stress state change,and on this basis,further analyzes the pretension dispersion and other factors that affect the fatigue of the bolted connection structure in the service stage.The law of influence on performance.First of all,this paper takes M10 bolt connection as an example,establishes a theoretical model of thread engagement considering the pitch deviation,and reveals the mechanism of stress redistribution.Then,in order to further quantitatively analyze the change law,a parameterized finite element single bolt tightening simulation model was established.By drawing the torque-pretension relationship curve under different manufacturing deviation,it was verified that the pretension formation mechanism is correct under the manufacturing deviation.By comparing the stress distribution cloud diagrams of bolt nodes under different manufacturing deviation,the correctness of the theory of stress redistribution on the contact surface is verified by manufacturing deviation,and a method to improve the bearing performance of bolts is proposed based on this.Finally,through a single bolt tightening test,the relationship between the pitch deviation and the thread friction torque,the end face friction torque and the bolt pretension is established,which verifies the rationality of the simulation model and the accuracy of the above-mentioned theory.On the basis of the above work,this paper studies the calculation of the actual bearing load of the bolt in service stage,analyzes the change of the bolt load in different stages,studies the influence of the dispersion of the pretension on the bolt load,and further analyzes the influence on the bolt load And then verify the accuracy of the influence law through the finite element simulation model.In this paper,the manufacturing deviation of the joint surface is brought into the process of bolt pretension formation during the tightening process,and its influence on the bolt load capacity in the service process is studied.Various aspects are analyzed from the perspective of the two continuous states of bolt tightening accuracy and bolt load capacity.The influence law of factors on the fatigue performance of bolt connections has certain guiding significance for the assembly process of bolts and the design of ring flange bolt connection structure.更多还原