I want to model a structure having very thin plates that join thicker solid structures. If I model the thin regions with shell elements and the thick ones with solids, how do I effect the moment transfer where they join?
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One way to effect moment transfer between the shells (that have rotational degrees of freedom) and solids (which do not) is to use contact elements (see section 9.2: "Modeling a Shell-Solid Assembly" in the Contact Technology Guide). An example input file demonstrating the procedure for a small cantilever beam model appears below. Input file: fini /cle /vie,1,1,1,1 /vup,1,z /pnu,type,1 /num,1 C******************************** C*** PARAMETERS C******************************** l=100 w=20 t=2 e=2e11/3 nu=0.3 uz_tip=-5 C******************************** C*** GEOMETRY C******************************** /prep7 bloc,,l/2,-w/2,w/2,-t/2,t/2 vatt,1,1,1 asel,none rect,l/2,l,-w/2,w/2 aatt,2,2,2 C******************************** C*** ATTRIBUTES, MESH C******************************** et,1,45 mp,ex,1,e mp,nuxy,1,nu et,2,43 mp,ex,2,e mp,nuxy,2,nu r,2,t vmes,all ames,all C******************************** C*** MOMENT TRANSFER CONTACT ELEMENTS C******************************** et,3,175 ! CONTACT NODE ATTRIBUTES (PLACEON SHELLS) keyo,3,2,2 ! MPC ALGORITHM keyo,3,12,5 ! ALWAYS BONDED keyo,3,4,0 ! RIGID SURFACE CONSTRAINT keyo,3,5,3 ! SHELL-SOLID CONSTRAINT et,4,170 ! TARGET SURFACE ATTRIBUTES (PLACE ON SOLIDS) ksel,s,loc,x,l/2 ! PUT CONTACT ELEMS ON SHELLS ksel,r,loc,z lslk,s,1 nsll,s,1 *get,nnds,node,,count type,3 real,3 nd=0 *do,i,1,nnds nd=ndnext(nd) e,nd *enddo asel,s,loc,x,l/2 ! PUT TARGET ELEMENTS ON SOLIDS nsla,s,1 esln type,4 real,3 esurf C******************************** C*** BOUNDARY CONDITIONS C******************************** asel,s,loc,x da,all,ux da,all,uy da,all,uz lsel,s,loc,x,l dl,all,,uz,uz_tip alls fini C******************************** C*** SOLVE C******************************** /solu alls solv fini C******************************** C*** POST PROCESS C******************************** /post1 plns,u,z |
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