ANSYS變層厚復(fù)合材料殼的定義

2017-03-02 by:CAE仿真在線來源:互聯(lián)網(wǎng)

對(duì)于疊層狀符合材料殼,可以采用shell181,shell91或shell99來模擬,通常推薦使用she
ll181,因?yàn)檫@個(gè)單元提供了最強(qiáng)的材料模型、非線性以及求解技術(shù)支持能力,而且可以方
便地進(jìn)行截面偏置或定義厚度函數(shù)。厚度函數(shù)可以指定隨坐標(biāo)變化的殼厚度,來模擬變厚
度殼。但對(duì)于shell181單元來說,厚度函數(shù)只用來控制殼的總厚度,并不能控制單層厚度
,各個(gè)疊層的厚度是由總厚度根據(jù)殼截面定義中輸入的各層厚度值按比例分配的。但有些
情況下,我們需要控制單層的厚度函數(shù),也就是說復(fù)合材料中只有某一層或幾層的厚度是
坐標(biāo)的函數(shù),而其余層的厚度并沒有變化,這種情況下就不能用總厚度來控制了:如下圖
所示的復(fù)合材料截面。

只有中間兩層的厚度在變化,這種情況下就需要我們根據(jù)函數(shù)指定中間兩層的厚度,而其
余層的厚度不變,這時(shí)用shell181單元就不好實(shí)現(xiàn)了?？梢杂胹hell91或shell99來實(shí)現(xiàn)這
種情況,這兩種殼單元和shell181不同,不是通過截面來定義鋪層,而是通過實(shí)常數(shù)定義
,可以定義每一個(gè)單層的變厚度,即每一層在四個(gè)角節(jié)點(diǎn)上的厚度。只要對(duì)每個(gè)單元定義
一個(gè)實(shí)常數(shù),其每一層的厚度通過實(shí)常數(shù)定義其對(duì)應(yīng)角節(jié)點(diǎn)所在位置的層厚度,就可以實(shí)
現(xiàn)層厚的函數(shù)化。由于每一層每個(gè)角節(jié)點(diǎn)的厚度值都是實(shí)常數(shù)中的某個(gè)數(shù)值,所以可以通
過RTHICK命令根據(jù)函數(shù)來修改實(shí)常數(shù),從而達(dá)到這樣一個(gè)目的。關(guān)于RTHICK命令的說明這
里不進(jìn)行詳細(xì)描述,可以參閱ANSYS幫助中對(duì)這個(gè)命令的詳細(xì)介紹,下面通過一個(gè)例子用sh
ell91單元來說明具體方法。

這個(gè)例子為20×10的一個(gè)板,如下圖所示。其厚度沿長邊方向變化,左半部分為32層,中
間兩層厚度由0.125逐漸收縮到0,其余層厚不變,右半部分為30層,情況類似?？梢詤㈤?
上圖,只是層數(shù)有所不同。

命令流如下(注:本例只是為了說明方法,殼的厚度偏大,可能并不適合用殼單元來模擬
,只是為了后處理中便于看到結(jié)果,實(shí)際結(jié)構(gòu)厚度可能小的多,您可以根據(jù)需要調(diào)整):

/prep7
ET,1,SHELL91,32,1
KEYOPT,1,11,0,
KEYOPT,1,8,1
ET,2,SHELL91,30,1
KEYOPT,2,11,0,
KEYOPT,2,8,1

MP,EX,1,135000
MP,EY,1,8800
MP,EZ,1,8800
MP,PRXY,1,0.33
MP,PRYZ,1,0.33
MP,PRXZ,1,0.33
MP,GXY,1,4470
MP,GYZ,1,4470
MP,GXZ,1,4470

RECTNG,0,10,0,10,
RECTNG,10,20,0,10,
AGLUE,all

LESIZE,all, , ,20, , , , ,1
!*

ASEL,S,LOC,X,0,10
MSHAPE,0,2D
MSHKEY,0
TYPE, 1
AMESH,all
allsel,all

ASEL,S,LOC,X,10,20
MSHAPE,0,2D
MSHKEY,0
TYPE, 2
AMESH,all
allsel,all

CSWPLA,11,0,1,1,
esys,11

*GET,MXNODE,NODE,,NUM,MAX,
*GET,MXELE,ELEM,,NUM,MAX,
*DIM,THICK,,MXNODE

ESEL,S,TYPE,,1
NSLE,S

*DO,ELE,1,MXELE
*IF,ESEL(ELE),EQ,1,THEN
R,ELE
RMODIF,ELE,1,32,0, , , ,0
RMODIF,ELE,13,1,45,0.125,0,0,0, !1
RMODIF,ELE,19,1,135,0.125,0,0,0, !2
RMODIF,ELE,25,1,90,0.125,0,0,0, !3
RMODIF,ELE,31,1,135,0.125,0,0,0, !4
RMODIF,ELE,37,1,45,0.125,0,0,0, !5
RMODIF,ELE,43,1,90,0.125,0,0,0, !6
RMODIF,ELE,49,1,135,0.125,0,0,0, !7
RMODIF,ELE,55,1,45,0.125,0,0,0, !8
RMODIF,ELE,61,1,0,0.125,0,0,0, !9
RMODIF,ELE,67,1,45,0.125,0,0,0, !10
RMODIF,ELE,73,1,135,0.125,0,0,0, !11
RMODIF,ELE,79,1,90,0.125,0,0,0, !12
RMODIF,ELE,85,1,135,0.125,0,0,0, !13
RMODIF,ELE,91,1,45,0.125,0,0,0, !14
RMODIF,ELE,97,1,0,0.125,0,0,0, !15
RMODIF,ELE,103,1,45,0.125,0,0,0, !16
RMODIF,ELE,109,1,135,0.125,0,0,0, !17
RMODIF,ELE,115,1,90,0.125,0,0,0, !18
RMODIF,ELE,121,1,45,0.125,0,0,0, !19
RMODIF,ELE,127,1,135,0.125,0,0,0, !20
RMODIF,ELE,133,1,90,0.125,0,0,0, !21
RMODIF,ELE,139,1,135,0.125,0,0,0, !22
RMODIF,ELE,145,1,45,0.125,0,0,0, !23
RMODIF,ELE,151,1,0,0.125,0,0,0, !24
RMODIF,ELE,157,1,45,0.125,0,0,0, !25
RMODIF,ELE,163,1,135,0.125,0,0,0, !26
RMODIF,ELE,169,1,90,0.125,0,0,0, !27
RMODIF,ELE,175,1,45,0.125,0,0,0, !28
RMODIF,ELE,181,1,135,0.125,0,0,0, !29
RMODIF,ELE,187,1,90,0.125,0,0,0, !30
RMODIF,ELE,193,1,135,0.125,0,0,0, !31
RMODIF,ELE,199,1,45,0.125,0,0,0, !32
*ENDIF
*ENDDO

*DO,NODE,1,MXNODE
*IF,NSEL(NODE),EQ,1,THEN
THICK(node) = 0.125-0.0125*NX(NODE)
*ENDIF
*ENDDO

RTHICK,THICK(1),105,106,107,108
RTHICK,THICK(1),111,112,113,114

*DO,NODE,1,MXNODE
THICK(node) =0

*ENDDO
ALLSEL,ALL

ESEL,S,TYPE,,2
NSLE,S

*DO,ELE,1,MXELE
*IF,ESEL(ELE),EQ,1,THEN
R,ELE
RMODIF,ELE,1,30,0, , , ,0
RMODIF,ELE,13,1,45,0.125,0,0,0, !1
RMODIF,ELE,19,1,135,0.125,0,0,0, !2
RMODIF,ELE,25,1,90,0.125,0,0,0, !3
RMODIF,ELE,31,1,135,0.125,0,0,0, !4
RMODIF,ELE,37,1,45,0.125,0,0,0, !5
RMODIF,ELE,43,1,90,0.125,0,0,0, !6
RMODIF,ELE,49,1,135,0.125,0,0,0, !7
RMODIF,ELE,55,1,45,0.125,0,0,0, !8
RMODIF,ELE,61,1,0,0.125,0,0,0, !9
RMODIF,ELE,67,1,45,0.125,0,0,0, !10
RMODIF,ELE,73,1,135,0.125,0,0,0, !11
RMODIF,ELE,79,1,90,0.125,0,0,0, !12
RMODIF,ELE,85,1,135,0.125,0,0,0, !13
RMODIF,ELE,91,1,45,0.125,0,0,0, !14
RMODIF,ELE,97,1,0,0.125,0,0,0, !15
RMODIF,ELE,103,1,45,0.125,0,0,0, !16
RMODIF,ELE,109,1,135,0.125,0,0,0, !17
RMODIF,ELE,115,1,90,0.125,0,0,0, !18
RMODIF,ELE,121,1,45,0.125,0,0,0, !19
RMODIF,ELE,127,1,135,0.125,0,0,0, !20
RMODIF,ELE,133,1,90,0.125,0,0,0, !21
RMODIF,ELE,139,1,135,0.125,0,0,0, !22
RMODIF,ELE,145,1,45,0.125,0,0,0, !23
RMODIF,ELE,151,1,0,0.125,0,0,0, !24
RMODIF,ELE,157,1,45,0.125,0,0,0, !25
RMODIF,ELE,163,1,135,0.125,0,0,0, !26
RMODIF,ELE,169,1,90,0.125,0,0,0, !27
RMODIF,ELE,175,1,45,0.125,0,0,0, !28
RMODIF,ELE,181,1,135,0.125,0,0,0, !29
RMODIF,ELE,187,1,90,0.125,0,0,0, !30
*ENDIF
*ENDDO

*DO,NODE,1,MXNODE
*IF,NSEL(NODE),EQ,1,THEN
THICK(node) = 0.125-0.0125*(NX(NODE)-10)
*ENDIF
*ENDDO

RTHICK,THICK(1),99,100,101,102
RTHICK,THICK(1),105,106,107,108

*DO,NODE,1,MXNODE
THICK(node) =0
*ENDDO

ALLSEL,ALL
/ESHAPE,1.0
EPLOT

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