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?
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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