Unit 4 �Riveted Connections
Metal sheets can be joined in several ways, such as using bolts, electric welding, or riveted connections. Among these, riveting is one method for connecting metal sheets together. Riveted connections can be observed in various applications, such as water tanks, cargo ships, or bridges that use rivets for connection.
Figure 4.1
“Pressure vessels” are mostly constructed from several curved metal sheets joined together to form the desired shape. One common method of joining is by using rivets.
d = The diameter size of the rivet.
t = The thickness of the metal sheet to be joined
p = Pitch refers to the distance between the centers of the longest rivets, measured parallel to the seam."
There are two types of riveted joints
Lap joint (a,b) and Butt joint (c,d)
1. Lap joint it is when two metal sheets overlap each other
Figure 4.2
2. Butt Joint It is when the sheets to be joined are aligned (in the same direction) and have one or two backing plates.
Figure 4.3
Principle of calculation
Principle of considering the pitch distance
1. Consider the row where the rivets are spaced the farthest apart
2. For cutting, only cut one span of the rivet
3. The cutting line must pass through the center of the rivet and be perpendicular to the edge of the joint, covering all rows of rivets.
4. Try cutting the pitch distance at the next rivet span. If the pitch distance you cut is the same, it indicates that the cut is correct. However, if it is not the same, it means the cut is incorrect, and you should cut again.
Example of considering the pitch distance for cutting
In design, it is possible to calculate the forces acting on an object that may cause damage, in order to avoid hazards to both property and individuals. The design can categorize the characteristics of damage in riveted work as follows
Characteristics of failure and breakage of rivets and joined sheets.
Consider one wide strip. = p Rivets and main plates can fail in the following scenarios
1. The rivet is sheared off
This can be expressed in the following equation
Shear resistance force. = Sheared area x Shear stress of the rivet.
Butt joint with parallel planes.
When. n = Number of rivets.
2. The plate was punctured and damaged by the rivets.
It can be expressed in the equation as follows.
Resistance to crushing force. = Area subjected to crushing. x Crushing stress of the rivet.
Fc = n x d x t x σc
Crushed area of each component. = Cross-sectional area of the rivet perpendicular to the line of force. = dt
When. n = Number of rivets.
d = Diameter of the rivet. t = Thickness of the metal plate
3. The plate is torn along the seam.
It can be expressed in the equation as follows
Tensile fracture resistance force perpendicular to the tensile force = Fractured area. x Tensile stress
Ft = ( p – d )t x σt
When. p = Width of the metal plate
d = Diameter of the rivet t = Thickness of the metal plate.
4 The plate is sheared at the rivet (the plate is gouged by the rivet, resulting in material loss).
It can be expressed in the equation as follows
Shear resistance force. = Sheared area x Shear stress.
When. a = The edge of the metal plate that is sheared to the center of the rivet. t = Thickness of the metal plate.
Fτ = 2a x t x τ
5. The plate tears around the rivet area
The tearing that occurs is caused by multiple factors, making calculations difficult.
6. The plate is torn along with the rivets.
7. The connection plate with a row of rivets is subjected to shear failure.
This can be expressed in the equation as follows
Total resistance force = Area of the sheared connection plate.+ Area of the sheared connection plate and area of the compressed rivet.
Area of the sheared connection plate = ( p – d )t
Area of the compressed rivet = d x t x σc
Note.
1. The characteristics of tearing or breaking of the rivets in situations 4 and 5 will not occur if the distance is specified.
a ≥ 1.5d For ductile steel used in design.
a ≥ 2d For aluminum or mild steel.
2. In good design, all components should fail simultaneously, meaning that the resistance forces acting on each component should be equal. This can be assessed in the design using the following equation:
Fs = Fc , Fs = Ft , Ft = Fc Such as.
Efficiency of the joint
The joint with the best efficiency is when the connecting plate has not yet been drilled for rivets and is a full plate. Considering the connecting plate width as 𝑝 under tensile force, the equation for the resistance force of the full plate is equal to
F = p.t.σt
The actual efficiency of the connection is taken as the minimum value obtained from the calculations.
Ex.1. Calculate the shear resistance force of the metal sheets that are joined together using 2 rivets with a diameter of 16 millimeters, where the shear stress is 360 Newtons per square millimeter.
Ex.2 Calculate the resistance force against shear failure perpendicular to the vertical direction of a connection plate with a pitch distance of 72 millimeters and a diameter of 28 millimeters. The steel plate has a thickness of 12 millimeters, and the tensile stress of the steel plate is 270 Newtons per square millimeter.
Ex.3 Calculate the resistance force against shear failure of a connection plate with a diameter of 40 millimeters. The steel plate has a thickness of 16 millimeters, and the compressive stress of the steel plate is 320 Newtons per square millimeter. Four rivets are used to connect the metal sheets.
Ex.4 Calculate the resistance force of a full plate in a shear connection with a row of rivets subjected to shear, with a pitch distance of 65 millimeters and a diameter of 30 millimeters. The steel plate has a thickness of 18 millimeters, with a compressive stress of 420 Newtons per square millimeter and a tensile stress of 260 Newtons per square millimeter. Also, determine the efficiency of the joint.
EXERCISE UNIT 4