Introduction:
In this question, we are given a figure showing the connection of a steel bar to an aluminum bar. We need to explain in detail how this connection is formed.

Connection of Steel Bar to Aluminum Bar:
The connection between the steel bar and the aluminum bar is formed using a mechanical joint. This type of joint is commonly used in various engineering applications where different materials need to be connected together.

Mechanical Joint:
A mechanical joint is a type of connection that relies on mechanical forces to hold the two components together. It is achieved by using fasteners such as bolts, screws, or rivets. In this case, the steel bar and aluminum bar are connected using bolts.

Bolts:
Bolts are cylindrical fasteners with a threaded shaft and a head at one end. They are commonly used in mechanical joints due to their ability to provide a strong and secure connection. In this case, bolts are used to connect the steel bar and aluminum bar together.

Connection Process:
The connection process involves the following steps:

1. Alignment: The steel bar and aluminum bar are aligned in the desired position to ensure a proper fit.

2. Drilling: Holes are drilled through both the steel and aluminum bars at predefined locations. These holes will accommodate the bolts.

3. Insertion of Bolts: Bolts are inserted through the holes in both bars. The threaded shaft of the bolt passes through the holes, while the head rests on the outer surface of the steel bar.

4. Tightening of Bolts: Nuts are placed on the threaded shaft of the bolts and tightened using a wrench or spanner. This creates a compressive force between the steel and aluminum bars, holding them securely together.

5. Locking: To prevent the bolts from loosening due to vibrations or external forces, locking mechanisms such as lock washers or thread-locking compounds may be used.

Advantages of Mechanical Joints:
- Mechanical joints provide a strong and secure connection between different materials.
- They are relatively easy to assemble and disassemble.
- Mechanical joints allow for flexibility and can accommodate dimensional changes due to temperature variations.
- They provide good load transfer between the connected components.

Conclusion:
The connection between the steel bar and aluminum bar is formed using a mechanical joint with bolts. This type of connection provides a strong and reliable bond between the two materials. The use of bolts allows for easy assembly and disassembly when required. Mechanical joints are commonly used in various engineering applications due to their numerous advantages.