What is rivet | Types of riveted joints - Mechanicaltalks - Mechanicaltalks

What is rivet | Types of riveted joints – Mechanicaltalks

Introduction

Riveted joints are the permanent joints which are mostly used in structural members. Riveted joints are preferably made of ductile materials pins which are called rivets which are inserted into the hole of members. Due to this hole, it weakens the section.

Here in this article we will discuss different types of riveted joints, important terms, failures and applications of riveted joints.

• Types of riveted joints 

Following are the two types of riveted joints, depending upon the way in which the members are connected –

1. Lap joint 

It is defined as a joint in which a part of one members overlaps the other and then the two members are riveted together.

2. Butt joint

A butt joint is that in which the main plates are kept in alignment which are butting ( touching ) each other and a cover plate is placed on one side or on both sides of the main plates. The cover plate is then riveted together with the main plates.

It has generally two types :

a) Single cover butt joint – It is defined as the joint in which the edge of the two members butt against each other and only one cover plate is placed on one side of the member and riveted together.

b) Double cover butt joint

It is defined as a joint in which the edge of the two members butt against each other and two cover plates are placed on each side of the member.

Apart from the above, following are the types of riveted joints depending upon the number of rows of the rivets :

a) Single riveted joints – It is defined as the joint in which there is a single row of rivets in a lap joint or there is a single row of rivets on each side in a butt joint.

b) Double riveted joints – A double riveted joint is one in which there are two rows of rivets in a lap joint or there are two rows of rivets in each side in a butt joint.

Note : Similarly the joints may be triple riveted or quadruple riveted.

Some special type rivets :

a) Chain riveted joints – Here in this joint every rivet of a row is opposite to the other rivets of the other row.

b) Zig – Zag riveted joints – It is a joint in which the spacing of the rivets are staggered in such a way that every rivet is in the middle of the two rivets of the opposite row.

c) Diamond riveted joints – It is defined as a joint in which the number of rivets decreases as we proceed from inner most row to the outer most row. It is adopted in butt joint only.

Important terms used in riveted joints

1) Pitch – It is the distance from the centre of one rivet to the centre of the next rivet measured parallel to the seam. It is denoted by P.

2) Back pitch – It is the perpendicular distance between the centre lines of the successive rows.

3) Diagonal pitch – It is the distance between the centres of the rivets in adjacent rows of zig zag riveted joint.

4) Margin or marginal pitch – It is the distance between the centre of rivet hole to the nearest edge of the plate.

• Failure of riveted joints :

A riveted joint may be failed due many reasons but the two major reasons are :

1. Failure of rivets

2. Failure of plates

1. Failure of rivets are consists of –

a) Shearing of rivets

The shearing resistance or pull required to shear off the rivet per pitch length is given by,

Ps = n × π/4 × d^2 × τ ( for single shear )

Ps = n × 2 × π/4 × d^2 × τ ( for double shear

Where, 

n= number of rivets per pitch length

τ = permissible shear stress for the rivet material.

b) Crushing ( bearing ) of rivets

The crushing resistance or pull required to crush the rivet per pitch length is given by,

Pc= n × d × t × σc

Where σc = permissible crushing stress for the rivet material.

2. Failure of plates are consists of –

a) Tearing of the plate at an edge

This phenomena of failure can be avoided by keeping the margin ( m ) = 1.5d, where d is the diameter of the rivet hole.

b) Tearing of the plate across the row of rivets

The tearing resistance or pull required to tear off the plate per pitch length is given by,

Pt = ( p – d ) × t × σc

Where p = pitch of the rivets

d = diameter of the rivet hole

t = thickness of the plate

σc = Permissible tensile stress for the plate material.

• Application of riveted joints

1. Riveted joints are mostly used in pressure vessels.

2. It has also a huge application in airplane structure.

3. It also used in construction of bridges or any other structural members.

4. Where there is Aluminium alloy, there will be rivets.

That was all about the Riveted joints. Hope you all like this article and it should have clear all you doubts. If you have any questions related to this or any mechanical engineering topics then let us know in comment box below or feel free to contact us through email. If this was helpful to you then share this article to your friends.

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