Before we go through the difference between a machine and a structure, let’s first see what they are. Once we comprehend that, understanding the difference between them will be a cakewalk for us.
A machine typically contains mechanisms that are designed to provide significant forces and transmit significant power. Some examples of machines are a food blender, an automobile transmission, a bulldozer, a robot, and an amusement park ride.
A structure is an assembly of resistant bodies (known as members) such that these bodies don’t have any relative motion between them. A structure is meant for carrying loads. For example, a building, a roof truss, a railway bridge, machine frames, etc.
The degree of freedom of a structure is zero. A structure with a negative degree of freedom is known as a preloaded structure.
The key differences between a machine and a structure are:
1. A machine transforms the available energy into some useful work, whereas in a structure no energy is transformed into useful work. The purpose of a structure is to bear the load for which it is designed.
2. Since a machine comprises of mechanisms, the parts of a machine move relative to one another. On the other hand, the members of a structure do not move relative to one another.
3. The links of a machine may transmit both power and motion, while the members of a structure transmit forces only.
4. A machine may consist of flexible links like belts and chains which undergo partial deformation when transmitting power and motion. On the other hand, a structure consists of only resistant bodies that undergo negligible deformation while bearing the load.