Learning Forum

[norbert.ionas]

Hi,

Would like to extract the working load of a Bolt which has a pretension on it using APDL commands.

Thanks,

N

[Ashish Khemka]

Hi,

 

You can use a Bolt Tool to extract the working load:

Regards,

Ashish Khemka

[wrbulat]

Hello Norbert,

I'd have to experiment with a test case to be absolutely sure this works, but I'd start by making sure that you save calculated nodal forces to the results file and set "Save MAPDL db" to "Yes" before solving. These settings are made in Analysis Settings Details.

Then, in a post processing command object, you could select the pretension elements and list forces using PRRSOL of PRRFOR:

resume

/post1

set,last

esel,s,ename,,179

nsle

prrfor

 

The reactions force listing would appear in either the solve.out or post.out file, depending on whether you run the create the post processing command object before or after solving.

 

 

 

Similarly, you could try this (if it works it'll show the net bolt load force in Details of the command object):

esel,s,ename,,179

nsle

esel,inve

nsle,u

esel,s,ename,,179

nsel,r,d,ux,-1e8,1e8

fsum

*get,my_net_bolt_load,fsum,,item,fx

Regards,

 

Bill

[庆森 陈]

hello, did you solve this problem ?

[norbert.ionas]

Yes, I did. thanks

[庆森 陈]

 

Can you describe the method?

If possible, please give the relevant APDL command.

Thanks.

 

[norbert.ionas]

total_nodes=0

ESEL,S,ENAME,,179                       !select all pretension elements PRETS179
CM,bp_comp,ELEM                         !creates a component for the bolt pretension elements
NSLE,S,POS,3                            !show/select head nodes for the pretension elements
CM,bphn_comp,NODE                       !creates a component for the bolt pretension head nodes
*GET,nr_nodes,NODE,0,COUNT              !getting the number of head nodes

total_nodes=nr_nodes

*GET,NR_STEPS,ACTIVE,0,SET,NSET                 !get total number of time steps
*DIM,nids,ARRAY,nr_nodes,7                      !array to store the forces
*DIM,bolt_force,ARRAY,NR_STEPS,nr_nodes+1       !array to store bolt forces

*IF,total_nodes,GE,1,THEN                !if at least one bolt pretension exist in the model
    *DO,i,1,NR_STEPS
        SET,,,,,,,i
        *GET,time,ACTIVE,0,SET,TIME
        bolt_force(i,1)=time
        
        *DO,q,1,nr_nodes
            column = q+1
            *GET,nodes,NODE,0,NUM,MIN               !get minimum node number
            *GET,nx,NODE,nodes,LOC,X                !gets x coordinate of the node
            *GET,ny,NODE,nodes,LOC,Y                !gets y coordinate of the node
            *GET,nz,NODE,nodes,LOC,Z                !gets z coordinate of the node
            
            NSEL,S,NODE,,nodes                      !select the identified head node
            
            my_force = 0
            *GET,my_force,NODE,nodes,RF,FX          !gets the bolt force
            bolt_force(i,column)=my_force

            CM,pproc_node,NODE                      !creates component for the post processed head nodes
            ESLN                                    !selects the pretnesion elements which are connected to the head node
            CM,pproc_sec,ELEM                       !creates component for the post processed pretension elements
            my_elem=ELNEXT(0)                       !select the first element from the list
            *GET,bpe_type,ELEM,my_elem,ATTR,TYPE    !get element type of the selected pretention element 

            NSLE
            ESLN
            my_elem=ELNEXT(0)                       !select the first element from the list
            !*GET,be_type,ELEM,my_elem,ATTR,TYPE     !get element type of the selected bolt element (issue with this approac when the bolt have two type of elements tetras and hex as they have different element id) 
            *GET,mat_id,ELEM,my_elem,ATTR,MAT       !get material id of the selected solid bolt element
        
            nids(q,1)=q
            nids(q,2)=nodes
            nids(q,3)=mat_id
            nids(q,4)=bpe_type
            nids(q,5)=nx
            nids(q,6)=ny
            nids(q,7)=nz
        
            !unselect processed elements and nodes
            CMSEL,S,bp_comp
            CMSEL,U,pproc_sec
            CM,bp_comp,ELEM
            CMSEL,S,bphn_comp
            CMSEL,U,pproc_node
            CM,bphn_comp,NODE
            *GET,rem_nr_nodes,NODE,0,COUNT
            !/com, **rem_nr_nodes: %rem_nr_nodes%
            CMSEL,S,bphn_comp
            *ENDDO
        ALLSEL
        ESEL,S,ENAME,,179                       !select all pretension elements PRETS179
        CM,bp_comp,ELEM                         !creates a component for the bolt pretension elements
        NSLE,S,POS,3                            !show/select head nodes for the pretension elements
        CM,bphn_comp,NODE  
    *ENDDO
*ENDIF

[庆森 陈]

Thanks, I will try.