Springs and dampers are key components in many vibration isolation, and dissipation systems; examples include springs and shock absorbers (dampers) used in cars, and in washing machines.
Figure 1. A spring (left) and shock absorber (right) attached to a washing machine tub to dampen vibrations to the outer cabinet of the machine.
Springs and dampers are common components found in many machines that experience vibration. Their design and selection is based on the forces that will be generated due to vibration, for any particular machine.
A spring works by storing energy and providing an opposing force that is directly proportional to its linear displacement. There are usually two types of linear displacement springs available:
- Compression springs, which have to be compressed
- Tension springs, which have to be stretched
The opposing force of the spring, Fspring, is determined by its spring constant, k, and its linear displacement, x, as follows:
Fspring = -k x
Springs on their own are not always sufficient in preventing vibrations because they tend to oscillate; this is why dampers or shock absorbers are used, because they dissipating energy from vibrations. The force to oppose vibrations in a damper, Fdamper, is proportional to the velocity of the motion, v. The force is also dependent on the damping coefficient, c, of the fluid in the damper. The force is calculated using this equation:
Fdamper = -c v
Dampers are useful in machines that pass through their natural frequency. Without damping a machine can observe very large oscillations that may lead to failure.
Springs and dampers are used as a means to control vibrations by dissipating the excess energy and controlling the motion; however, this does not solve the issue of vibration at the root of the problem. The XYO Balancer Technology automatically and dynamically compensates for imbalances in a machine, and thus addresses vibration at its source; using this technology it is possible to lessen the demand for heavy and expensive springs and dampers in rotating machinery.