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[求助]
求教有关ANSYS梁壳模型静力学分析刚度阵不正定的问题
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小学渣开始学习APDL语言时间不是很久，尝试用SHELL181与BEAM188一起画了一个钢桥，桥面是壳单元，其余部分都是梁单元，如图1所示，看上去挺科学的但是如果尝试求解的话会提示：【刚度阵不正定，一般来说存在没有被约束住的刚体模态。】但是反复看来看去学弱都觉得写的没什么大错orz，求各位大神指点迷津，不甚感谢。因为写的比较长，材料组数等相对比较多，所以悬赏分数也相应地提高了一些。.png#opennewwindow) 图1：单元示意图 附录：APDL代码： /PREP7 Fail=600e6 !Fail Stress of the material DPipe=5 !Diameter of the pillars TCPP=0.001 !Thickness of the pillars DArc=8 !Diameter of the Arc TCArc=0.01 !Thickness of the Arc DASupport=2!Diamter of the supportive lines TCSupport=0.01!Thickness of the supportive lines TCSH=0.001 !Thickness of the plate TCSH2=0.01 !Thickness of the second plate H=50 !Height of the bridge DeltaX=150 !DeltaX of the pillars DeltaZ=16 !Wedth of the bridge Dividen=13 !Dividen of the arc Young2=210e9 !E of the second material Miu2 =0.3 !Miu of the second material DENS2=7800 !Density of the second material ShellMeshSize=10 PillarMeshSize =50 ArcMeshSize=500 SpprtMeshSize=20 *DIM,DivXi,ARRAY,Dividen-1,1,1 *DO, I, 1,Dividen-1, DivXi(I)=I*DeltaX/Dividen *ENDDO !* Set the Element ET,1,BEAM188 ET,2,SOLID185 ET,3,SHELL181 !Set the Material !Material 1 MPTEMP,,,,,,,, !Material Temperature MPTEMP,1,0 MPDATA,DENS,1,,7800 MPTEMP,,,,,,,, MPTEMP,1,0 MPDATA,EX,1,,210e9 MPDATA,PRXY,1,,0.3 !Material 2 MPTEMP,,,,,,,, MPTEMP,1,0 MPDATA,EX,2,,Young2 MPDATA,PRXY,2,,Miu2 MPTEMP,,,,,,,, MPTEMP,1,0 MPDATA,DENS,2,,DENS2 !Set the section !Pillars SECTYPE, 201, BEAM, CTUBE, Pillars, 0 SECOFFSET, CENT SECDATA,DPipe/2,TCPP+DPipe/2,0,0,0,0,0,0,0,0,0,0 !Pillar at the middle SECTYPE, 202, BEAM, CTUBE, Pillarmiddle, 0 SECOFFSET, CENT SECDATA,DPipe/2,DPipe/2+TCPP/2,0,0,0,0,0,0,0,0,0,0 !Arc SECTYPE, 203, BEAM, CTUBE, ARC, 0 SECOFFSET, CENT SECDATA,DArc/2,DArc/2+TCArc,0,0,0,0,0,0,0,0,0,0 !Supportive lines SECTYPE, 204, BEAM, CTUBE, Supportive, 0 SECOFFSET, CENT SECDATA,DASupport/2,DASupport/2+TCSupport,0,0,0,0,0,0,0,0,0,0 !Shell sect,205,shell,,Plate secdata, TCSH,2,0.0,3 secoffset,MID seccontrol,,,, , , , !Set the failure FC,1,S,XTEN, Fail FC,1,S,YTEN, Fail FC,1,S,ZTEN, Fail FC,1,S,XCMP,-Fail FC,1,S,YCMP,-Fail FC,1,S,ZCMP,-Fail !Modeling !Model the bridge surface !Modeling the keypoints *DO, I, 1, 6, K, I,(I-1)*DeltaX,H,0 *ENDDO *DO, I, 1, 5, K,6+I,I*DeltaX,0,0 *ENDDO *DO, I, 1, 6, K,11+I,(I-1)*DeltaX,H,DeltaZ *ENDDO *DO, I, 1, 5, K,17+I,I*DeltaX,0,DeltaZ *ENDDO ! Modeling the Areas A,1,12,13,2 A,2,3,14,13 A,3,4,15,14 A,4,5,16,15 A,5,6,17,16 !Modeling the Pillars !Modeling the keypoints K,23,0*DeltaX,0,0 K,24,0*DeltaX,0,DeltaZ !Modeling the Pipes *Do,I,1,5 LSTR,1+I,6+I *ENDDO *Do,I,1,5 LSTR,12+I,17+I *ENDDO !Modeling the Arc !Modeling the keypoints *Do,I,1,5 K,24+I,(I-0.5)*DeltaX,H,0 K,29+I,(I-0.5)*DeltaX,H,DeltaZ *ENDDO !Modeling the Pipes *Do,I,1,4 LARC,17+I,18+I,30+I LARC,6+I,7+I,25+I *ENDDO LARC,24,18,30 LARC,23,7 ,25 !Modeling the supportive Lines *DIM,B,ARRAY,10,1,1 B(1)=35,34,32,30,28,27,29,31,33,36 *DIM,C,ARRAY,10,1,1 C(1)=2 ,14,11, 8, 5, 7,10,13,16, 4 counter=35 counter2=35+(Dividen-1)*10 Rarc=((DeltaX/2)**2+H**2)/(2*H) Theta0=asin(DeltaX/2/Rarc)*2 Hi=sqrt(Rarc**2-(DeltaX/2)**2) *DO,I,1,Dividen-1, Tanhaha=(DivXi(I)-DeltaX/2)/Rarc Theta=asin(Tanhaha)+0.5*Theta0 haha=Theta/Theta0 !haha=1-haha *DO,J,1,5, KL,B(J),haha,counter, KL,C(J),1/Dividen*I,counter2, counter=counter+1 counter2=counter2+1 *ENDDO I=Dividen-I *DO,J,6,10, KL,B(J),haha,counter, KL,C(J),1/Dividen*I,counter2, counter=counter+1 counter2=counter2+1 *ENDDO *ENDDO counter=35 numpillar=(Dividen-1)*10 *DO,I,1,numpillar, LSTR,counter,counter+numpillar counter=counter+1 *ENDDO *if，abs(nint(Dividen/2)-Dividen/2),le,0.3,then !If dividen is even LDELE,37+(Dividen/2-1)*10,37+(Dividen/2-1)*10+9,0, !Delete the length zero lines *endif !Meshing the shells asel,all AATT, 2, , 3, 0, 205 mshkey,1 LESIZE,ALL,,,ShellMeshSize amesh,all allsel !Meshing the Pillars lsel,S,,,17,20, lsel,A,,,22,25, LATT,1, ,1, , , ,201 mshkey,1 LESIZE,ALL,,,PillarMeshSize lmesh,all allsel !Meshing the Pillars Middle lsel,S,,,26,26, lsel,A,,,21,21, LATT,1, ,1, , , ,202 mshkey,1 LESIZE,ALL,,,PillarMeshSize lmesh,all allsel !Meshing the Arc lsel,S,,,27,36, LATT,1, ,1, , , ,203 mshkey,1 LESIZE,ALL,,,ArcMeshSize lmesh,all allsel !Meshing the Supportive Lines lsel,S,,,37,37+(Dividen-1)*10, LATT,1, ,1, , , ,204 mshkey,1 LESIZE,ALL,,,SpprtMeshSize lmesh,all allsel /sol !Fix the DOFS on the bottom KSEL,S,,, 7,11, KSEL,A,,,18,24, DK,ALL, ALL,0, allsel !Fix the DOFS on the left LSEL,S,,,1, DL,ALL,, ALL,0, allsel !Fix the DOFS on the right to apply symmetry boundary LSEL,S,,,15, LSEL,A,,,21, LSEL,A,,,26, ! DL,ALL,, UX,0, DL,ALL,,ALL,0, allsel !Gravity ON ACEL,0,0,-9.8, |
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