Mechanical StructuresEnergy and Power Considerations
Energy is required to produce vibration and in the case of machine vibration, this energy comes from the source of power to the machine. This energy source can be the AC power line, an internal combustion engine, or steam driving a turbine, etc. Energy is defined as force multiplied by the distance over which the force acts, and the SI unit of energy is the Joule. One Joule of energy is equivalent to a force of one Newton acting over a distance of one meter. The physical concept of work is similar to that of energy, and the units used to measure work are the same as those for measuring energy.
The actual amount of energy present in the machine vibration itself is usually not very great compared to the energy required to operate the machine for its intended task.
Power is defined as the rate of doing work, or the rate of energy transfer, and according to the SI, it is measured in Joules per second, or Watts. One horsepower is equivalent to 746 watts. Power is proportional to the square of the vibration amplitude, just as electrical power is proportional to the voltage squared or the current squared.
According to the law of conservation of energy, energy cannot be created or destroyed, but it can be transformed into different forms. The vibratory energy in a mechanical system is ultimately dissipated in the form of heat.