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Posts tagged with "tutorial"

[ansys] vm4 铰接支承变形

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两根相同的钢材料棒,铰接在一起,铰接处施加一个向下的力F,求解钢棒中的应力和铰接点的位移,忽略钢棒的自重。

静态分析,使用Link1单元模拟。 这个问题相当简单,没有太多内容要研究的。

/COM,ANSYS MEDIA REL. 10.0 (05/31/2005) REF. VERIF. MANUAL: REL. 10.0
/VERIFY,VM4
/PREP7
/TITLE, VM4, DEFLECTION OF A HINGED SUPPORT
C***     STR. OF MATL., TIMOSHENKO, PART 1, 3RD ED., PAGE 10, PROB. 2
L=15*12                         ! LENGTH OF BAR IN INCHES
*AFUN,DEG                       ! TRIG FUNCTIONS IN DEGREES 
THETA=30                        ! ANGLE TO BE USED TO CALCULATE A AND B
A=2*L*COS(THETA)                ! CALCULATED X LOCATION - NODE 3
B=L*SIN(THETA)                  ! CALCULATED Y LOCATION - NODE 2
ET,1,LINK1
R,1,.5
MP,EX,1,30E6
N,1
N,2,A/2,-B                      ! X LOCATION = A/2; A AND B AS ABOVE
N,3,A                           
E,1,2
E,2,3
D,1,ALL,,,3,2
F,2,FY,-5000
OUTPR,,1
FINISH
/SOLU    
SOLVE
FINISH
/POST1 
MID_NODE = NODE (A/2,-B,0 )
*GET,DISP,NODE,MID_NODE,U,Y 
LEFT_EL = ENEARN (MID_NODE) 
ETABLE,STRS,LS,1  
*GET,STRSS,ELEM,LEFT_EL,ETAB,STRS 

*DIM,LABEL,CHAR,2
*DIM,VALUE,,2,3
LABEL(1) = 'STRS_psi','DEF_in'
*VFILL,VALUE(1,1),DATA,10000,-0.120
*VFILL,VALUE(1,2),DATA,STRSS,DISP
*VFILL,VALUE(1,3),DATA,ABS(STRSS /10000 ) ,ABS( DISP /0.120 )
/OUT,vm4,vrt
/COM
/COM,------------------- VM4 RESULTS COMPARISON ---------------------
/COM,
/COM,         |   TARGET   |   ANSYS   |   RATIO
/COM,
*VWRITE,LABEL(1),VALUE(1,1),VALUE(1,2),VALUE(1,3)
(1X,A8,'   ',F10.3,'  ',F10.3,'   ',1F5.3)
/COM,----------------------------------------------------------------
/OUT

FINISH
*LIST,vm4,vrt

[ansys] vm9 不等刚度弹簧横向大变形

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Large Lateral Deflection of Unequal Stiffness Springs

两弹簧系统,受力F (F=5*sqrt(2)) 作用,求系统的应变能以及节点位移。

此问题的求解是通过增加质量,和slow dynamics技术(包括估计临界阻尼)。组合单元(COMBIN40)用于提供x, y方向的阻尼。阻尼系数分别为 cx = 2 * sqrt(Kx * m) ,cy = 2 * sqrt(Ky * m) 这里 m 是任意值,这里假定为1, Kx 和 Ky 在求解之前不能得到,所以用 `Ky = k2 = 1N/cm` 和 `Kx = Ky/2 = 0.5 N/cm` 来近似。

注意到cx和cy的定义都是临界阻尼的定义式,根据临界阻尼的性质,当时间无限长时,单自由度系统的自由振动响应趋于0。kx和ky是如何选择的呢?如果更换别的值,得出的结果就完全不对了。 对此疑问很大:confused:

由于对载荷的抵抗是变形位置的函数,所以进行大变形分析。使用 POST1 获得结果

/COM,ANSYS MEDIA REL. 10.0 (05/31/2005) REF. VERIF. MANUAL: REL. 10.0
/VERIFY,VM9
/PREP7
/TITLE, VM9, LARGE LATERAL DEFLECTION OF UNEQUAL STIFFNESS SPRINGS
/COM, REF: G.N. VANDERPLAATS, "NUMERICAL OPTIMIZATION TECHNIQUES FOR
/COM,      ENGINEERING DESIGN", PP 72-73, MCGRAW-HILL, 1984
ET,1,COMBIN14,,,2          ! UX AND UY DOF ELEMENT
ET,3,COMBIN40,,,,,,2       ! ALL MASS IS AT NODE J, UX DOF ELEMENT
ET,4,COMBIN40,,,2,,,2      ! ALL MASS IS AT NODE J, UY DOF ELEMENT
R,1,1                      ! SPRING STIFFNESS = 1
R,2,8                      ! SPRING STIFFNESS = 8
/COM USE COMBIN40 MASS, K, AND DAMPING C, TO APPROX. CRITICAL DAMPING
R,3,,1.41,1                ! C = 1.41, M = 1
R,4,,2,1                   ! C = 2, M = 1
N,1
N,2,,10
N,3,,20
N,4,-1,10
N,5,,9
LOCAL,11,0,0,0,0,45        ! 定义一个局部坐标系,将 x 轴移动45度
NROTAT,2                   ! 将节点 2 的节点坐标系旋转到当前的局部坐标系,这样即将施加的45度载荷就与局部坐标系x轴一致了。
E,1,2                      ! ELEMENT 1 IS SPRING ELEMENT WITH STIFFNESS 1
REAL,2
E,2,3                      ! ELEMENT 2 IS SPRING ELEMENT WITH STIFFNESS 8
TYPE,3
REAL,3
E,4,2                      ! ELEMENT 3 IS COMBINATION ELEMENT WITH C = 1.41
TYPE,4
REAL,4
E,5,2                      ! ELEMENT 4 IS COMBINATION ELEMENT WITH C = 2
NSEL,U,NODE,,2
D,ALL,ALL
NSEL,ALL
FINISH
/SOLU    
ANTYPE,TRANS               ! 瞬态动力学分析 FULL TRANSIENT DYNAMIC ANALYSIS
NLGEOM,ON                  ! 大变形 LARGE DEFLECTION
KBC,1                      ! STEP BOUNDARY CONDITION
F,2,FX,7.071068            ! 载荷在旋转后的节点坐标系内 FORCE IS IN ROTATED NODAL COORDINATE SYSTEM 
AUTOTS,ON
NSUBST,20
OUTPR,,20
OUTPR,VENG,20
TIME,15                    ! ARBITRARY TIME FOR SLOW DYNAMICS
SOLVE
FINISH
/POST1
SET,,,,,15                 ! USE ITERATION WHEN TIME = 15
ETABLE,SENE,SENE           ! 应变能 STORE STRAIN ENERGY
SSUM                       ! 相加 SUM ALL ACTIVE ENTRIES IN ELEMENT STRESS TABLE
*GET,ST_EN,SSUM,,ITEM,SENE
PRNSOL,U,COMP              ! PRINT DISPLACEMENTS IN GLOBAL COORDINATE SYSTEM
*GET,DEF_X,NODE,2,U,X
*GET,DEF_Y,NODE,2,U,Y
*DIM,LABEL,CHAR,3,2
*DIM,VALUE,,3,3
LABEL(1,1) = 'STRAIN E','DEF_X (C','DEF_Y (C'
LABEL(1,2) = ', N-cm  ','m)      ','m)      '
*VFILL,VALUE(1,1),DATA,24.01,8.631,4.533
*VFILL,VALUE(1,2),DATA,ST_EN ,DEF_X,DEF_Y
*VFILL,VALUE(1,3),DATA,ABS(ST_EN/24.01), ABS(8.631/DEF_X), ABS(DEF_Y/4.533 )
/COM
/OUT,vm9,vrt
/COM,------------------- VM9 RESULTS COMPARISON ---------------------
/COM,
/COM,                 |   TARGET   |   ANSYS   |   RATIO
/COM,
*VWRITE,LABEL(1,1),LABEL(1,2),VALUE(1,1),VALUE(1,2),VALUE(1,3)
(1X,A8,A8,'   ',F10.3,'  ',F10.3,'   ',1F5.3)
/COM,----------------------------------------------------------------

/OUT
FINISH
*LIST,vm9,vrt

[ansys] vm3 热载荷结构

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Thermally Loaded Support Structure

铜线和钢线悬挂在墙上,下面连接刚性的梁,通过梁施加一个力Q, 同时有一个dT的热载荷。求解铜线和钢线的应力

分析
使用了2D spar单元,下面的三个节点4, 5, 6使用CP进行y方向位移的耦合处理。另外,对于加热造成的热膨胀,设定任意的参考温度70F, 和加载的温度80F(意味着+10F的温度载荷)。结果通过ETABLE进行处理。

INP

finish
/clear
/COM,ANSYS MEDIA REL. 10.0 (05/31/2005) REF. VERIF. MANUAL: REL. 10.0
/VERIFY,VM3
/PREP7
/TITLE, VM3, THERMALLY LOADED SUPPORT STRUCTURE
C***      STR. OF MATL., TIMOSHENKO, PART 1, 3RD ED., PAGE 30, PROB. 9
ANTYPE,STATIC             ! STATIC ANALYSIS
ET,1,LINK1
R,1,.1
MP,EX,1,16E6
MP,ALPX,1,92E-7           ! alpx, alpy, alpz 热膨胀系数?
MP,EX,2,30E6
MP,ALPX,2,70E-7
TREF,70                   ! REFERENCE TEMPERATURE
N,1,-10                   ! DEFINE NODES AND ELEMENTS
N,3,10   
FILL
N,4,-10,-20
N,6,10,-20   
FILL
E,1,4   
E,3,6
MAT,2
E,2,5
CP,1,UY,5,4,6             ! 耦合4, 5, 6三个节点的Y向位移
D,1,ALL,,,3               ! BOUNDARY CONDITIONS AND LOADING
F,5,FY,-4000
BFUNIF,TEMP,80            ! UNIFORM TEMPERATURE (TREF+10)
FINISH
/SOLU    
OUTPR,BASIC,1       
OUTPR,NLOAD,1             
NSUBST,1
SOLVE
FINISH
/POST1                                
STEEL_N  = NODE (,,,)                      ! 选择节点
COPPER_N = NODE (10,0,0)      
STEEL_E = ENEARN (STEEL_N)                 ! 选择单元
COPPER_E = ENEARN (COPPER_N)
ETABLE,STRS_ST,LS,1                        ! LINK1单元的ls,1表示SAXL: Axial stress in the element
ETABLE,STRS_CO,LS,1   
*GET,STRSS_ST,ELEM,STEEL_E,ETAB,STRS_ST  
*GET,STRSS_CO,ELEM,COPPER_E,ETAB,STRS_CO

*DIM,LABEL,CHAR,2,2
*DIM,VALUE,,2,3
LABEL(1,1) = 'STRSS_ST','STRSS_CO'
LABEL(1,2) = ' (psi)  ',' (psi)  '
*VFILL,VALUE(1,1),DATA,19695,10152 
*VFILL,VALUE(1,2),DATA,STRSS_ST,STRSS_CO
*VFILL,VALUE(1,3),DATA,ABS(STRSS_ST/19695 ) ,ABS( STRSS_CO/10152 )
/COM
/OUT,vm3,vrt
/COM,------------------- VM3 RESULTS COMPARISON ---------------------
/COM,
/COM,                 |   TARGET   |   ANSYS   |   RATIO
/COM,
*VWRITE,LABEL(1,1),LABEL(1,2),VALUE(1,1),VALUE(1,2),VALUE(1,3)
(1X,A8,A8,'   ',F10.0,'  ',F10.0,'   ',1F5.3)
/COM,----------------------------------------------------------------
/OUT

FINISH
*LIST,vm3,vrt

[ansys] vm2 梁应力与变形

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Beam Stresses and Deflections

一根标准工字梁在中部有两处支撑,同时部分段受到均布载荷,要求梁中点位置的应力和位移

  • 分析使用2D梁单元(beam3: 两节点,每个节点3个自由度ux, uy, rotz)
  • 注意均布载荷为线载荷 (N/M)
  • 单元输出位置是at 9 intermediate locations
  • 根据beam3的单元说明,是用于etable的输出选项,确定table里各输出项的意义。


/SHOW, JPEG 将输出指向JPEG图形,所以在GUI模式下看不到输出。可以将这句注释掉。

/TITLE 设定此次分析的名称,可在输出图形上显示。

KEYOPT 与单元相关的选项设置。不同单元具有不同的附加功能,通过此命令设定。

MID_NODE = NODE (240,,, ) 获取坐标为(240,0,0)的节点标号

MID_ELM = ENEARN (MID_NODE) 获取靠近节点MID_NODE的单元的标号

ETABLE,STRS,LS,3 怎么解?

COM,ANSYS MEDIA REL. 10.0 (05/31/2005) REF. VERIF. MANUAL: REL. 10.0
/VERIFY,VM2
JPGPRF,500,100,1             ! MACRO TO SET PREFS FOR JPEG PLOTS
/SHOW,JPEG
/PREP7    
MP,PRXY,,0.3
/TITLE, VM2, BEAM STRESSES AND DEFLECTIONS
C***        STR. OF MATL., TIMOSHENKO, PART 1, 3RD ED., PAGE 98, PROB. 4
ANTYPE,STATIC                
ET,1,BEAM3
KEYOPT,1,9,9                  ! OUTPUT AT 9 INTERMEDIATE LOCATIONS
R,1,50.65,7892,30
MP,EX,1,30E6
N,1                           ! DEFINE NODES AND ELEMENTS
N,5,480
FILL
E,1,2
EGEN,4,1,1
D,2,UX,,,,,UY                 ! BOUNDARY CONDITIONS AND LOADING
D,4,UY
SFBEAM,1,1,PRES,(10000/12)      
SFBEAM,4,1,PRES,(1E4/12)
FINISH
/SOLU    
OUTPR,BASIC,1
SOLVE
FINISH
/POST1
SET,1,1
PRNSOL,U,COMP
PRNSOL,ROT,COMP
PLDISP,1
MID_NODE = NODE (240,,, )               
*GET,DISP,NODE,MID_NODE,U,Y         
MID_ELM = ENEARN (MID_NODE)       
ETABLE,STRS,LS,3              
*GET,STRSS,ELEM,MID_ELM,ETAB,STRS

*DIM,LABEL,CHAR,2
*DIM,VALUE,,2,3
LABEL(1) = 'STRS_psi','DEF_in'
*VFILL,VALUE(1,1),DATA,-11400,0.182
*VFILL,VALUE(1,2),DATA,STRSS,DISP
*VFILL,VALUE(1,3),DATA,ABS(STRSS /11400 ) ,ABS( DISP /0.182 )
/OUT,vm2,vrt
/COM
/COM,-------------------VM2 RESULTS COMPARISON ---------------------
/COM,
/COM,         |   TARGET   |   ANSYS   |   RATIO
/COM,
*VWRITE,LABEL(1),VALUE(1,1),VALUE(1,2),VALUE(1,3)
(1X,A8,'   ',F10.3,'  ',F10.3,'   ',1F5.3)
/COM,---------------------------------------------------------------
/OUT
FINISH
*LIST,vm2,vrt

[ansys] vm1 静不定支反力分析

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Statically Indeterminate Reaction Force Analysis

等截面杆两端固定,中间受到相反方向的力的作用,求两端支撑的支反力。

因为物理模型只受到轴向的拉伸,所以可以使用杆单元(spar)来分析,这里使用的是单元link1。另外只对支反力感兴趣,不需要应力应变的结果,所以杆单元的横截面可以给任意值。

需要注意的是此问题是一个静不定问题,在理论力学里面可以使用虚功原理来求解(假设有一个微小位移,然后建立平衡方程进行求解)。

link1 2D两节点杆单元,每节点两个自由度ux, uy,只能承受轴向的拉伸和压缩,可以模拟truss, link, spring

FSUM Sums the nodal force and moment contributions of elements. 对于不受外载荷的节点来说,其对所有相连节点的作用力和力矩的总和必然为0,在此例题中,如果在1、2节点之间多加入一个节点,则此节点的FSUM值等于0

OUTPR 定义结果输出。用于控制输出的内容,对于规模较大的模型,可以使用此命令输出必要的结果,控制结果文件大小。


/COM,ANSYS MEDIA REL. 10.0 (05/31/2005) REF. VERIF. MANUAL: REL. 10.0
/VERIFY,VM1
/PREP7
/TITLE, VM1, STATICALLY INDETERMINATE REACTION FORCE ANALYSIS
C***      STR. OF MATL., TIMOSHENKO, PART 1, 3RD ED., PAGE 26, PROB.10
ANTYPE,STATIC                  ! STATIC ANALYSIS
ET,1,LINK1
R,1,1                          ! CROSS SECTIONAL AREA (ARBITRARY) = 1
MP,EX,1,30E6
N,1
N,2,,4
N,3,,7
N,4,,10
E,1,2                          ! DEFINE ELEMENTS
EGEN,3,1,1
D,1,ALL,,,4,3                  ! BOUNDARY CONDITIONS AND LOADING
F,2,FY,-500
F,3,FY,-1000
FINISH
/SOLU    
OUTPR,BASIC,1                  ! output basic quantities
OUTPR,NLOAD,1                  ! output element nodal loads
SOLVE
FINISH
/POST1
NSEL,S,LOC,Y,10                ! 选取适当节点
FSUM                           ! 获得节点力
*GET,REAC_1,FSUM,,ITEM,FY      ! 赋值给某变量
NSEL,S,LOC,Y,0
FSUM
*GET,REAC_2,FSUM,,ITEM,FY

*DIM,LABEL,CHAR,2
*DIM,VALUE,,2,3
LABEL(1) = 'R1, lb','R2, lb '
*VFILL,VALUE(1,1),DATA,900.0,600.0
*VFILL,VALUE(1,2),DATA,ABS(REAC_1),ABS(REAC_2)
*VFILL,VALUE(1,3),DATA,ABS(REAC_1 / 900) ,ABS( REAC_2 / 600)
/OUT,vm1,vrt
/COM
/COM,------------------- VM1 RESULTS COMPARISON ---------------------
/COM,
/COM,         |   TARGET   |   ANSYS   |   RATIO
/COM,
*VWRITE,LABEL(1),VALUE(1,1),VALUE(1,2),VALUE(1,3)
(1X,A8,'   ',F10.1,'  ',F10.1,'   ',1F5.3)
/COM,----------------------------------------------------------------
/OUT
FINISH
*LIST,vm1,vrt