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模态分析相关,可以看看
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:
- /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
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