悬臂搅拌轴动力特性研究.pdf

单位代码:10010
学号
硕士研究生学位论文
题目悬臂搅拌轴动力特性研究
京化工学
人由片
专业化工过程机械
研究生
李建丰
指导教师徐鸿教授
Xw1B02-2
日期
2003年1月8日
北京化工大学硕士学位论文
悬臂搅拌轴动力特性研究
摘要
本论文中所指的搅拌轴包括轴本身和随轴转动的附件,如搅拌器、联轴器等。
在本课题研究中,建立了搅拌轴的三种有限元模型,即有限元实体模型及简化的
梁盘模型、梁壳模型,在这几种模型中的轴承简化为刚性约束,并采用这三种有
限元模型分别计算了搅拌轴临界转速,且与经验公式计算的临界转速值进行了比
较;借助参数化有限元模型讨论了搅拌轴结构参数对临界转速的影响,并用实例
验证了有限元法求解搅拌轴临界转速的正确性与有效性。将搅拌器上的流体作用
力简化为一个主矩和主矢;为考虑作用在搅拌轴上的惯性力效应,根据平衡精度
预设搅拌器的初始偏心;在转子动力学软件 ROTOR中建立搅拌轴的梁盘模型,分
别计算了搅拌轴在空载和搅拌工况下的动力响应,并进一步讨论了动力响应与工
作转速、轴径和轴长的关系。最后在动力响应的基础上对搅拌轴进行了疲劳分析。
对搅拌轴动力特性的研究得到下列较重要的结论:(1)现行搅拌轴临界转速
经验公式的计算值相对于空载时的临界转速值偏大,搅拌轴在搅拌工况下的临界
转速值因被搅拌介质的阻尼作用而减小,介质粘度越大,阻尼作用越强,临界转
速值越小。(2)在搅拌轴的众多结构参数中调节搅拌轴的轴径、搅拌器离底距和
层间距对调节临界转速最有效。(3)采用有限元法计算搅拌轴动力响应,能真实
反映搅拌轴自激振动、流体激振对动力响应的放大作用。(4)对一定结构的搅拌
轴存在一个适于其工作的转速区,搅拌轴运行在这个转速区时,动力响应值很小
(5)当搅拌轴动力响应超过许用范围时,按照搅拌轴转速、叶片通过频率应远离
临界转速的原则调整搅拌轴结构参数,改变搅拌轴轴径、调节搅拌器离底距和层
间距对调节搅拌轴动力响应非常有效。
关键词:搅拌轴,临界转速,动力响应,疲劳分析
北京化工大学硕士学位论文
A STUDYON DYNAMIC RESPONSE
OF CANTILEVER AGITATING SHAFT
ABSTRACT
In this thesis, agitating shaft is defined as an assembly including shaft
and accessories, such as agitators, shaft couplings. Mechanical bearings
are simplified as inflexible constraints. 3-D finite element solid model
simplified beam-shell model and beam-disk model are built. Critical speeds
of agitating shaft are obtained by performing modal analysis of three finite
element models. The results from above methods are compared and
analyzed. With the solid model, the effects of structural parameters on
critical speed are studied. The correctness and efficiency of the results from
FEM are proved by experiments. Hydraulic forces applied on the agitator
are simplified as a main moment and a main force on the agitating shaft,
Initial decentration of agitator is determined based on the balance standard
The dynamic responses, such as fluctuating bending stresses and dynamic
deflections, of the agitating shaft under no-liquid and normal working
conditions are studied. The relations between dynamic responses and
working speed, structural parameters, are discussed. Lastly, fatigue analysis
of the agitating shaft is also performed based on the dynamic response
results