Bolt

Bolted Plates

Tested with CGX 2.19 / CCX 2.19

• Non-linear static analysis
• Surface-to-surface penalty contact
• Thermal shrinkage for bolt pre-tension.

File	Contents
Bolt.geo	Gmsh script for geomentry and meshing
pre.fbd	CGX script, pre-processing
post.fbd	CGX script, post-processing, movie
thermal.inp	CCX input
test.py	python script to run the simulation

The model represents one half of two plates and two bolts. The lower plate is fixed at the outer sides, the upper plate is pulled up vertically in the center. The bolt is pre-stressed by thermal shrinkage.

Pre-Processing

Contact surfaces and node sets for constraints:

• nsym1 and nsym2 are set to UX=0 (symmetry)
• nc2r is constrained to UY=UZ=0 (support)
• In step 1, the bolt is cooled down to pre-tighten it.
• In step 2, nsym1 is displaced to UZ=0.001 (displacement-controlled loading)

Parameter	Value	Meaning
d	10	nominal bolt diameter in mm
s	17	key-width of head and nut in mm
k	7	height of bolt head in mm
db	11	diameter of holes in mm
t1	10	thickness of upper plate in mm
b1	40	width of upper plate in mm
l1	40	length of upper plate in mm
t2	15	thickness of lower plate in mm
b2	50	width of lower plate in mm
l2	45	length of lower plate in mm
e	20	distance of bolt axis from plane of symmetry in mm

You may adjust the parameter values in the file Bolt.geo and then run

> gmsh Bolt.geo
> cgx -b pre.fbd

Solving

> ccx thermal
> monitor.py thermal

Post-Processing

> cgx -b post.fbl

Stress and contact pressure after pre-tensioning

Stress and contact pressure under external load