Patran中怎么提取模态质量呢？

hit126

　　在论坛中看见一些关于ansys的模态质量提取的方法，现在想要知道MSC.Patran中怎样可以提取到?

NASA

http://forum.vibunion.com/thread-91342-1-1.html

wangyibo407

楼主，你会了么？

sd

模态分析过程中打开振型型则化开关命令的Nrmkey设置为ON)，ANSYS程序将自动将每阶模态的最大位移单位化，就可以提取模态质量。计算方法如下：

1、利用SSUM对ETABLE动能数据求和获得结构总动能（ ）；

2、 将结构总动能除以 得到 ，其中 是系统的角频率。下面是《ANSYS Verification Manual》VM89.DAT稍加修改后提取模态质量的例子：代码:/PREP7
/TITLE, VM89, NATURAL FREQUENCIES OF A TWO-MASS-SPRING SYSTEM
C*** VIBRATION THEORY AND APPLICATIONS, THOMSON, 2ND PRINTING, PAGE 163,EX 6.2-2
ET,1,COMBIN14,,,2
ET,2,MASS21,,,4
R,1,200 ! SPRING CONSTANT = 200
R,2,800 ! SPRING CONSTANT = 800
R,3,.5 ! MASS = .5
R,4,1 ! MASS = 1
N,1
N,4,1
FILL
E,1,2 ! SPRING ELEMENT (TYPE,1) AND K = 200 (REAL,1)
TYPE,2
REAL,3
E,2 ! MASS ELEMENT (TYPE,2) AND MASS = .5 (REAL,3)
TYPE,1
REAL,2
E,2,3 ! SPRING ELEMENT (TYPE,1) AND K = 800 (REAL,2)
TYPE,2
REAL,4
E,3 ! MASS ELEMENT (TYPE,2) AND MASS = 1 (REAL,4)
TYPE,1
REAL,1
E,3,4 ! SPRING ELEMENT (TYPE,1) AND K = 200 (REAL,1)
M,2,UX,3
OUTPR,BASIC,1
D,1,UY,,,4
D,1,UX,,,4,3
FINISH


/SOLU
ANTYPE,MODAL
MODOPT,subspa,2,,,2,ON
MXPAND,2,,,YES
SOLVE
FINISH


/post1


set,1,1
etabl,kene,kene
ssum

*get,keneval1,ssum,,item,kene
*get,freqval1,mode,1,freq
eigen1=(2*3.14159*freqval1)**2

pmass1=2*keneval1/eigen1


set,1,2
etabl,kene,kene
ssum
*get,keneval2,ssum,,item,kene
*get,freqval2,mode,2,freq
eigen2=(2*3.14159*freqval2)**2
pmass2=2*keneval2/eigen2


finish