Vibrations can arise through internal excitation such as mechanical or hydrodynamic processes
or external ones such as wind loads or earthquakes.
Internal excitations mostly arise from rotating masses originating from the operation of machines, aggregates and processing facilities. Typical sources are pumps, centrifuges, compressors, rolling mills, presses, forge hammers and other large machine tools.
Moreover, internal excitation frequently arises in pipe systems of processing facilities through flowdynamic processes in the transport of fluids or gases. Hazardous peak loads can also be caused by incidents such as pressure surges resulting from water hammer or the sudden closure of valves.
External excitations due to factors such as wind and earthquakes can also cause severe damage or complete destruction of structures. Wind loads can in fact create serious problems in high buildings and slender bridges. Earthquakes can produce powerful shocks with a high risk of cracks and the collapse of entire constructions.
Traffic loads are also very often a source of unwanted vibrations. Railways in densely inhabited areas may cause discomfort by raising noise and vibrations levels in plants and buildings. Furthermore, slender and light bridges, such as footbridges for instance, may build up vibrations originating even from pedestrians.