ANSYS动力学分析的几个入门例子

ANSYS动力学分析的几个入门例子问题一：悬臂梁受重力作用发生大变形，求其固有频率。图片附件: 1.jpg ( 4.85 K )

基本过程：

1、建模

2、静力分析

NLGEOM,ON

STRES,ON

3、求静力解

4、开始新的求解：modal

STRES,ON

UPCOORD,1,ON 修正坐标

SOLVE...

5、扩展模态解

6、察看结果

/PREP7

ET,1,BEAM189 !使用beam189梁单元MPTEMP,,,,,,,,

MPTEMP,1,0

MPDATA,EX,1,,210e9

MPDATA,PRXY,1,,0.3

MPDATA,DENS,1,,7850

SECTYPE, 1, BEAM, RECT, secA, 0 !定义梁截面secA SECOFFSET, CENT

SECDATA,0.005,0.01,0,0,0,0,0,0,0,0

K, ,,,, !建模与分网

K, ,2,,,

K, ,2,1,,

LSTR, 1, 2

LATT,1, ,1, , 3, ,1

LESIZE,1, , ,20, , , , ,1

LMESH, 1

FINISH

/SOL !静力大变形求解

ANTYPE,0

NLGEOM,1

PSTRES,ON !计及预应力效果

DK,1, , , ,0,ALL, , , , , ,

ACEL,0,9.8,0, !只考虑重力作用

TIME,1

AUTOTS,1

NSUBST,20, , ,1

KBC,0

SOLVE

FINISH

/SOLUTION

ANTYPE,2 !进行模态求解

MSA VE,0

MODOPT,LANB,10

MXPAND,10, , ,0 !取前十阶模态

PSTRES,1 !打开预应力效应MODOPT,LANB,10,0,0, ,OFF

UPCOORD,1,ON !修正坐标以得到正确的应力PSOLVE,TRIANG !三角化矩阵

PSOLVE,EIGLANB !提取特征值和特征向量FINISH

/SOLU

EXPASS,1 !扩展模态解

PSOLVE,EIGEXP

FINISH

/POST1

SET,LIST !观察结果

FINISH

问题二：循环对称结构模态分析

这是ANSYS HELP里的例子，但那个命令流似乎有些问题，下面是整理过的命令流。

图片附件: 2.gif ( 18.74 K )

基本过程：

1、建模

2、define cyclic

3、定义约束

4、求模态解

5、展开并察看结果

r1=5 !建模

r2=10

d1=2

nsect=24

alpha_deg=360/nsect

alpha_rad=2*acos(-1)/nsect

/prep7

csys,1

k,1,0,0,0

k,2,0,0,d1

k,3,r1,0,0

k,4,r1,0,d1

l,3,4

arotat,1,,,,,,1,2,alpha_deg/2

k,7,r2,0,0

k,8,r2,0,d1

l,7,8

arotat,5,,,,,,1,2,alpha_deg/2

arotat,2,,,,,,1,2,alpha_deg/2

arotat,6,,,,,,1,2,alpha_deg/2

a,5,6,10,9

mshkey,1

et,1,181

r,1,0.20

r,2,0.1

mp,ex,1,10e6

mp,prxy,1,0.3

mp,dens,1,1e-4

esize,0.5

asel,,,,1,4

aatt,,1

asel,,,,5

aatt,,2

allsel

CYCLIC, , , ,'CYCLIC' !定义基本扇区AMESH,all !分网FINISH

/SOL !求模态解ANTYPE,2

MODOPT,LANB,10

MXPAND,10, , ,0

PSTRES,0

MODOPT,LANB,10,0,0, ,OFF

DK,5, , , ,0,UZ, , , , , ,

SOLVE

FINISH

/POST1

SET,LIST

SET, , ,1, , , ,4,

/CYCEXPAND, ,ON

PLNS,U,SUM !观察扩展模态

FINISH

问题三：三角平台受谐波载荷作用,求结构响应

谐波载荷为作用在平台上面一点的集中力，幅值为10N，频率范围5Hz~70Hz

基本过程：

1、建模

2. 求模态解

3、用模态叠加法作谐分析

4. 观察结果

/PREP7 !建模

ET,1,BEAM189

ET,2,SHELL93

R,1,0.01, , , , , ,

MP,EX,1,210e9

MP,PRXY,1,0.3

MP,DENS,1,7850

SECTYPE, 1, BEAM, RECT, secA, 0 SECOFFSET, CENT

SECDATA,0.005,0.008,0,0,0,0,0,0,0,0

K, ,-0.5,,,

K, ,0.5,,,

K, ,,,1,

K, ,,1,1,

K, ,-0.5,1,,

K, ,0.5,1,,

K, ,,,0.5,

A,4,5,6

LSTR, 1, 5

LSTR, 3, 4

LSTR, 2, 6

LSEL,S,LINE,,4,6

LATT,1,1,1, , 7, ,1

LSEL, , , ,ALL

LESIZE,ALL, , ,10, , , , ,1

LMESH,4,6

TYPE, 2

MSHAPE,0,2D

MSHKEY,1

AMESH,1

FINISH

/SOL !为了使用模态叠加法谐分析ANTYPE,2

MODOPT,LANB,20 !先取结构前20阶模态MXPAND,20, , ,0

MODOPT,LANB,20,0,0, ,OFF

KSEL,S,KP,,1,3

DK,ALL, , , ,0,ALL, , , , , ,

SOLVE

FINISH

!/POST1 !最好事先看一下模态结果