Massefjærdempere

Massefjærdempere, also known as tuned mass dampers (TMDs), are passive vibration control devices. They are designed to reduce or eliminate resonant vibrations in structures. A TMD consists of a mass attached to a spring and a damping mechanism. This system is tuned so that its natural frequency is close to the dominant natural frequency of the structure it is designed to protect. When the structure begins to vibrate at its resonant frequency, the TMD oscillates out of phase with the structure. This oscillation absorbs energy from the structure, effectively reducing the amplitude of the vibrations.

The principle behind a TMD is the concept of resonant frequency. Every object has a natural frequency at which it will vibrate most readily when disturbed. If external forces, such as wind or earthquakes, excite a structure at its resonant frequency, the vibrations can become dangerously large. A TMD works by introducing a secondary vibrating system that counteracts the primary vibrations. The mass in the TMD is designed to be significant relative to the mass of the structure, and the stiffness of the spring and the damping coefficient are carefully chosen to achieve the desired tuning.

Massefjærdempere are commonly used in a variety of applications. Tall buildings, bridges, and even some rotating machinery benefit from their implementation to mitigate wind-induced vibrations, seismic response, and operational vibrations. The effectiveness of a TMD depends on its mass ratio to the structure, the damping ratio of the TMD itself, and the accuracy of its tuning to the structure's dominant frequency. While effective, TMDs add mass and complexity to a structure and require careful design and installation.