梁单元与壳单元在固有振动计算中的比较

分别采用ANSYS中的beam188单元和shell63单元对圆筒形结构进行有限元建模,利用APDL语言编制了程序,计算了长径比为4～20的圆筒形结构的自由振动特性,对固有频率和模态进行了分析.结果表明,对于长径比>10的筒形结构,采用ANSYS中以Timoshenko梁为基础的单元基本可以满足要求;对于长径比<6的筒形结构,需根据工程实际,采用更接近结构实际情况的单元(如壳单元或体单元)建立模型,以提高计算结果的准确性.

Comparison of Beam Element and Shell Element in Analyzing Inherent Vibration of Structures

Finite element models of tube structures are set up using ANSYS with beam 188 element and shell63 element respectively.The computing programs are written by means of APDL language,the free vi-bration characteristics of tube structures with length-to-diameter ratios of 4~20 are computed.Also,the cor-responding inherent frequencies and modes are analyzed.The results show that as to tube structures with length-to-diameter larger than 10,the beam element of ANSYS based on Timoshenko beam can meet our re-quirements;but as to tube structures with length-to-diameter smaller than 6,in order to improve the accuracy,elements which are more close to real structures such as shell element or solid element should be used ac-cording to practical engineering.