The following procedure is adopted for the design of
circumferential lap joint for a boiler.
1. Thickness of the shell and diameter of rivets. The
thickness of the boiler shell and thediameter of the rivet will be same as for
longitudinal joint.
3. Pitch of rivets.
Knowing the efficiency of the circumferential lap joint ,
the pitch of the rivets for the lap joint may be obtained by using the relation
ECCENTRIC LOADED RIVETED JOINT
When the
line of action of the load does not pass through the centroid of the rivet
system and thus all rivets are not equally loaded, then the joint is said to be
an eccentric loaded riveted joint, as shown in Fig. (a).
The eccentric loading results in secondary shear caused by the tendency of force
to twist the joint about the centre of gravity in addition to direct shear or
primary shear.
Let P = Eccentric load on the joint, and
e =
Eccentricity of the load i.e. the distance between the line of action of
the load and the centroid of the rivet
system i.e. G.
The following procedure is adopted for the design of an
eccentrically loaded riveted joint.
From the
above expression, the value of F1 may be calculated and hence F2
and F3 etc. are known. The direction of these forces are at right angles
to the lines joining the centre of rivet to the centre of gravity of the rivet
system, as shown in Fig (b), and should produce the moment in the same
direction (i.e. clockwise or anticlockwise) about the centre of gravity,
as the turning moment (P × e).
No comments:
Post a Comment