公司動(dòng)態(tài)
news聯(lián)系我們
contact聯(lián)系電話:13986118909
13986962795
地址:武漢市漢陽(yáng)區(qū)江城大道298號(hào)麥普利斯廣場(chǎng)B座16樓
發(fā)布時(shí)間:2023-03-13 11:18:10 瀏覽次數(shù):818次
武漢建策工程咨詢有限公司?譚成煌
本次學(xué)習(xí)的是基于ansys apdl語(yǔ)言,已知索的受力狀態(tài)(有力態(tài)),求初始態(tài)(無(wú)力態(tài))的方法。
列舉實(shí)例,我們晾衣服采用的繩索,如何做到晾曬衣服后,保證衣服不接觸地面,或離地面有要求的精確距離,那么我們就要在制作晾衣繩時(shí),就要提前確定好長(zhǎng)度,長(zhǎng)度確定即確定了線型,才能保證繩索的工作態(tài)。如下圖:
繩晾衣服圖
轉(zhuǎn)成工程實(shí)例,采用直徑為d=0.2m的鋼繩,牽過(guò)跨度為120m的塔上,并受11個(gè)集中荷載100T后,要求垂度為50m,求鋼繩的長(zhǎng)度和初始態(tài)。草圖簡(jiǎn)要如下所示:
求解條件和求解問(wèn)題已明確,想要解決此問(wèn)題,實(shí)質(zhì)上就是對(duì)索結(jié)構(gòu)進(jìn)行找形。索結(jié)構(gòu)的形態(tài)其實(shí)是非線性大位移的問(wèn)題,因?yàn)樗鹘Y(jié)構(gòu)的形狀和應(yīng)力形態(tài)是成相互影響的。所以,其索的有力態(tài)是很難事先提前找到的,也就是不知道空纜態(tài)的。因?yàn)榧纫獫M足假設(shè)的初始形態(tài),又要滿足假設(shè)的預(yù)加力的分布,這利用常規(guī)的方法很難達(dá)到。由于計(jì)算軟件的非線性功能強(qiáng)大,可以借助有限元軟件進(jìn)行對(duì)索的找形求解。主要的方法是采用迭代,通過(guò)軟件不斷的往下更新模型狀態(tài),與施加荷載產(chǎn)生的位移相加的和慢慢逼近所需的結(jié)果。如下圖:
即,通過(guò)軟件不斷的往下更新模型,提取跨中節(jié)點(diǎn)坐標(biāo)+本次更新后模型的受力位移:fi+△dy=逼近目標(biāo)值。當(dāng)所求得的值滿足我們所設(shè)定的誤差范圍內(nèi)時(shí),命令程序退出迭代,即求解完成。理論上很簡(jiǎn)單,但將理論落實(shí)到地確實(shí)很難,需要不斷的摸索與反復(fù)嘗試比對(duì)。計(jì)算過(guò)程動(dòng)畫(huà)演示如下:
FINISH
/CLEAR
/FILNAME,EX820
/PREP7
L0=120 !跨度120m
XH=0
AREA=0.0314 !m2 d=0.2m r=0.1 A=0.1*0.1*3.14=0.0314m2
Ex=2.06E7 !規(guī)范2.06E5mpa=2.06E8KN/m2。10KN=1tonf。2.06E7tonf/m2。
Dens=7.85 !7.85tonf
Prxy=0.31
*dim,xy1,array,61,2
Q0=1 !1 tonf
QF=100 !100 tonf
ERR0=1/10000 !結(jié)束誤差
enum=60
istran=0.000006 !初始應(yīng)變
ET,1,10
R,1,AREA,istran !在實(shí)常數(shù)中給初應(yīng)力
MP,EX,1,EX
MP,PRXY,1,0.31
MP,DENS,1,DENS
k,1
k,2,L0,-XH
L,1,2
LESIZE,ALL,,,ENUM
LMESH,ALL
NSEL,s,node,,3,61,1 !節(jié)點(diǎn)3-61
cm,zk,node
allsel,all
d,1,all !等效=d,all,ux d,all,uy d,all,uz
D,2,all
*do,i,3,61,1
!ddele,i,ux
!ddele,i,uy
!D,i,uz
!d,i,ux,0
!D,i,ux
*enddo
!同上 ddele,zk,ux ddele,zk,uy
NODE1=NELEM(ENUM/2,1)
NODE2=NELEM(ENUM/2,2)
ACEL,,1
*do,i,7,57,5
f,i,fy,-100
*enddo
FINISH
PASS1=1
*DOWHILE,PASS1
/SOLU
ANTYPE,0
NLGEOM,ON
SSTIF,ON
cnvtol,f,,0.01,2,1 !非線性收斂準(zhǔn)則,根據(jù)計(jì)算情況修改。程序默認(rèn)值是5/1000.
NSUBST,60
OUTRES,ALL,ALL
SOLVE
FINISH
/POST1
SET,LAST,LAST
!UPCOORD,1,1
!*GET,LOCY,NODE,32,LOC,Y
!*get,UY0,node,32,u,Y
RAODU=ABS(uy(32)+ny(32))
AAA=ny(32)
BBB=UY(32)
!ERR1=abs(5-RAODU)/5
!raodu=abs(LOCY+UY0)
err1=(50-raodu)/50
!PLDISP,2
plnsol,u,y
FINISH
/PREP7
*do,i,1,61,1
*get,xy1(i,1),node,i,loc,x
*get,xy1(i,2),node,i,loc,y
*enddo
*if,ERR1,lt,0.5,THEN !LT小于,GT大于
UPGEOM,0.1,LAST,LAST,EX820,RST
*ELSE
UPGEOM,5,LAST,LAST,EX820,RST
*ENDIF
*IF,ERR1,LT,ERR0,EXIT
*if,RAODU,gt,50,exit
*if,abs(uy(32)),gt,50,exit
*ENDDO
本次學(xué)習(xí)的軟件:ansys,梯滴威(比對(duì))。
本次參考的書(shū)籍:《ansys工程結(jié)構(gòu)數(shù)值分析》?王新敏;《ansys參數(shù)化編程與命令手冊(cè)》?王新敏
感謝某公司分公司副總經(jīng)理周總的技術(shù)指導(dǎo)。
本次學(xué)習(xí)了ansys中的dowhile循環(huán)語(yǔ)句的使用,并結(jié)合if設(shè)置滿足誤差條件使程序在條件下執(zhí)行運(yùn)算,知道滿足相應(yīng)規(guī)則退出。也學(xué)習(xí)了在計(jì)算找形時(shí),所注意的各種相應(yīng)的開(kāi)關(guān),如打開(kāi)非線性,打開(kāi)大位移,打開(kāi)剛度硬化效應(yīng)等,并反復(fù)查找過(guò)程中的發(fā)散(不收斂)問(wèn)題,最終確定了迭代合適的步長(zhǎng)和更新模型因子,否則就很難收斂。
下面利找形的結(jié)果,提取初始線性,算受力態(tài)是否與假定相符。
FINISH
/CLEAR
/FILNAME,EX820
/PREP7
L0=120 !跨度120m
XH=0
AREA=0.0314 !m2 d=0.2m r=0.1 A=0.1*0.1*3.14=0.0314m2
Ex=2.06E7 !規(guī)范2.06E5mpa=2.06E8KN/m2。10KN=1tonf。2.06E7tonf/m2。
Dens=7.85 !7.85tonf
Prxy=0.31
*dim,xy1,array,61,2
Q0=1 !1 tonf
QF=100 !100 tonf
ERR0=1/1000 !結(jié)束誤差
enum=60
istran=0.000006 !初始應(yīng)變
ET,1,10
R,1,AREA,istran !在實(shí)常數(shù)中給初應(yīng)力
MP,EX,1,EX
MP,PRXY,1,0.31
MP,DENS,1,DENS
N,1,0.00000000,0.00000000
N,2,120.000000,0.00000000
N,3,1.66774346,-2.74920970
N,4,3.33639244,-5.49609014
N,5,5.00594810,-8.24064085
N,6,6.67641157,-10.9828614
N,7,8.34778402,-13.7227512
N,8,10.1093031,-16.0968529
N,9,11.8718471,-18.4686240
N,10,13.6354173,-20.8380632
N,11,15.4000148,-23.2051693
N,12,17.1656407,-25.5699412
N,13,19.0574415,-27.5524739
N,14,20.9503994,-29.5325233
N,15,22.8445155,-31.5100869
N,16,24.7397906,-33.4851626
N,17,26.6362256,-35.4577482
N,18,28.6949672,-36.9995653
N,19,30.7549384,-38.5385274
N,20,32.8161391,-40.0746310
N,21,34.8785693,-41.6078726
N,22,36.9422288,-43.1382486
N,23,39.1816212,-44.1469650
N,24,41.4220757,-45.1522378
N,25,43.6635899,-46.1540629
N,26,45.9061616,-47.1524363
N,27,48.1497883,-48.1473539
N,28,50.5189397,-48.5083222
N,29,52.8885416,-48.8653113
N,30,55.2585889,-49.2183191
N,31,57.6290767,-49.5673437
N,32,60.0000000,-49.9123829
N,33,62.3709233,-49.5673437
N,34,64.7414111,-49.2183191
N,35,67.1114584,-48.8653113
N,36,69.4810603,-48.5083222
N,37,71.8502117,-48.1473539
N,38,74.0938384,-47.1524363
N,39,76.3364101,-46.1540629
N,40,78.5779243,-45.1522378
N,41,80.8183788,-44.1469650
N,42,83.0577712,-43.1382486
N,43,85.1214307,-41.6078726
N,44,87.1838609,-40.0746310
N,45,89.2450616,-38.5385274
N,46,91.3050328,-36.9995653
N,47,93.3637744,-35.4577482
N,48,95.2602094,-33.4851626
N,49,97.1554845,-31.5100869
N,50,99.0496006,-29.5325233
N,51,100.942559,-27.5524739
N,52,102.834359,-25.5699412
N,53,104.599985,-23.2051693
N,54,106.364583,-20.8380632
N,55,108.128153,-18.4686240
N,56,109.890697,-16.0968529
N,57,111.652216,-13.7227512
N,58,113.323588,-10.9828614
N,59,114.994052,-8.24064085
N,60,116.663608,-5.49609014
N,61,118.332257,-2.74920970
E,1,3
*DO,I,3,60,1
E,I,I+1
*ENDDO
E,61,2
!LESIZE,ALL,,,ENUM
!LMESH,ALL
!NSEL,s,node,,3,61,1 !節(jié)點(diǎn)3-61
!cm,zk,node
!allsel,all
d,1,all !等效=d,all,ux d,all,uy d,all,uz
D,2,all
!ddele,i,ux
!ddele,i,uy
!D,i,uz
!d,i,ux,0
!D,i,ux
!同上 ddele,zk,ux ddele,zk,uy
NODE1=NELEM(ENUM/2,1)
NODE2=NELEM(ENUM/2,2)
ACEL,,1
!*do,i,7,57,5
!f,i,fy,-100
!*enddo
FINISH
!PASS1=1
!*DOWHILE,PASS1
/SOLU
ANTYPE,0
NLGEOM,ON
SSTIF,ON
!cnvtol,f,,0.01,2,1 !非線性收斂準(zhǔn)則,根據(jù)計(jì)算情況修改。程序默認(rèn)值是5/1000.
NSUBST,10
OUTRES,ALL,ALL
SOLVE
FINISH
計(jì)算簡(jiǎn)圖如下:
與找形結(jié)果一致。垂度=50.002
節(jié)點(diǎn) | 節(jié)點(diǎn)號(hào) | x | y | dy | y+dy |
N | 32 | 60 | -49.360 | -0.6403 | -50.0003 |
比對(duì):
采用不同的軟件進(jìn)行計(jì)算比對(duì),利用ansys找形的到的最終形態(tài),反算初始形態(tài)。下圖為最終一次找形前的初始態(tài)。
比對(duì)空纜線性,采用原坐標(biāo)導(dǎo)入CAD比對(duì):
原坐標(biāo)對(duì)比2中軟件的空纜線性,基本完全吻合。
提取空纜狀態(tài)下受F=1000KN的集中荷載的線性結(jié)果。受集中力F后,跨中最終大位移為50.011m,與我們初定的50m目標(biāo)值誤差僅為2/10000,與ansys求得的位移值50.0003基本一致。
其2種軟件最終結(jié)果對(duì)比;
軟件 | 節(jié)點(diǎn) | 節(jié)點(diǎn)號(hào) | F集 中力 | x | y | dy(m) | y+dy (m) | 目標(biāo)值f(m) | 誤差 |
ANSYS | N | 32 | 100tonf | 60 | -49.36 | -0.6403 | -50 | -50 | 6E-06 |
TDV | N | 31 | 1000KN | 60 | -49.361 | -0.6504 | -50.011 | -50 | 0.00022 |
△ | - | - | - | - | 0.00068 | 0.01012 | 0.01088 | - | - |
其結(jié)果有誤差原因可能是2種軟件輸入的材料特性方式不一樣,截面特性也不一樣,一種是直接四舍五入后直接填入軟件,后者是采用軟件自帶材料特性和截面工具輸入,所以截面特性上有區(qū)別。另外,集中力的輸入一個(gè)采用的tonf為單位,一個(gè)是KN,此處也有區(qū)別。
總結(jié)與心得,待續(xù)。
返回頂部
13986118909
13986962795
微信二維碼