水轮发电机主轴螺栓联接的有限元分析

针对"某水轮发电机主轴螺栓联接仅采用传统的安全系数法设计,得出的水轮发电机主轴无垫片螺栓联接的最大应力为72.0 MPa,可靠性不高"的问题,运用ANSYS软件,建立了由精细结构和一般结构组成的主轴螺栓联接有限元模型,精细结构为对称的1/12螺栓联接结构;一般结构只模拟上/下法兰,不包含螺栓,用来传递主轴的扭转力矩;两部分之间运用约束方程联接;采用了TARGE170/CONTA174单元模拟螺栓与法兰轴接触,PREST179单元模拟螺栓预紧。计算了在额定工作状态下,有/无14.5 mm垫片的主轴螺栓联接结构应力分布。研究结果表明,有/无14.5 mm垫片两种主轴螺栓联接结构均满足强度要求;无垫片结构的螺栓最大应力为92.6 MPa,比由安全系数法得到的结果大28.61%;有垫片结构的各部件应力增大4.10%~8.55%,螺栓最大应力为96.4 MPa,比无垫片结构增大4.10%。

Finite element analysis of bolted connection of hydro-generator shaft

Aiming at the problem that the low reliability of the result that the maximum stress of bolted connection without gaskets is 72.0 MPa,which is obtained by the traditional safety factor method applied to design the bolted connection of the hydro-generator shaft,a nonlinear finite dement model of the bolted connection of the hydro-generator shaft was built by ANSYS,which composed of the fine structure and the general structure.Both parts were connected with constraint equations.The fine structure was a symmetrical 1/12 bolt coupling structure.The general structure,not including the bolts,only simulated the up/down flange which transmitted the torsional moment of the shaft.Elements of TARGE170/CONTA174 and PREST179 were used to simulate the bolt-flange contact and the bolts preload respectively.The stress distribution of the bolted connection structure of the main shaft under the rated working condition with/without 14.5 mm gaskets was calculated.The results indicate that the strength requirements of the bolted connection structure with/without 14.5 mm gaskets of the main shaft can be both satisfied.In terms of the no-gaskets structure,the maximum stress of the bolts is 92.6 MPa which increases by 28.61％ compared with the results obtained by the safety factor method.In terms of the structure with gaskets,the maximum stress of each component increases by 4.10％～8.55％.The maximum stress of the bolts is 96.4 MPa,which increases by 4.10％ compared with the no-gaskets structure.