pid${}_{bolt}$, pid${}_{plate}$, cid, $sf$, $t_{beg}$, $t_{end}$
Parameter definition
pid${}_{bolt}$ Bolt part ID
pid${}_{plate}$ Plate part ID
cid ID of a CURVE or FUNCTION defining bolt shaft stress versus time
$sf$ Shaft stress curve scale factor
default: 1
$t_{beg}$ Start time
$t_{end}$ End time
default: 1.0e20

This command is used to prestress a set of bolts and to apply balancing forces to the surface of the holes in which the bolts are attached. pid${}_{bolt}$ is assumed to contain one or several bolts. pid${}_{plate}$ must have holes matching the bolts. The command identifies the discrete bolts and holes and creates bolt-hole pairs. The bolt shafts are prestressed with the axial stress defined by curve cid.

Prestress blind hole bolt
Bolted connection
Bolted connection

The following commands define an axial bolt shaft stress of 100MPa. The bolt is in part 3 and the threaded base plate in part 1. The applied shaft stress ramps up from 0 to 100MPa and is then held constant.

# Step 1 - pre-stress
sig_pre = 100.0, "bolt shaft stress"
tend = 0.005, "termination time"
0, 0, ALL
"base plate"
1, 1
"mounted plate"
2, 1
"M12 bolt"
3, 2
"M12 bolt"
3, 1, 200
"shaft stress versus time"
smooth_d(%sig_pre, 0.0, %tend/2)

The OUTPUT command is defined to output state files for the complete model at termination. These state file are to be included in the next modeling stage, where the bolt is merged to the hole in the base plate:

# Step 2 - inlcude state from Step 1
# elements, nodes and final state after Step 1
# file with *MERGE command, locking the bolt to base plate

impetus_state_boltX.k contains a MERGE command that locks bolt to the hole:

"bolt (0,0)"
G, 10001, G, 10002
208, 0, 95.0
10070, 0, 95.0

Each bolt hole pair has its own MERGE definition. As a consequence merge.out will have one force history curve for each connection.

Bolted connection under shear load
Bolted connection under shear load