26-07-2016, 12:36 PM
A tuned mass damper, also known as a harmonic absorber, is a device mounted in structures to reduce the amplitude of mechanical vibrations. Their application can prevent discomfort, damage, or outright structural failure. They are frequently used in power transmission, automobiles, and buildings.
Tuned mass dampers stabilize against violent motion caused by harmonic vibration. A tuned damper reduces the vibration of a system with a comparatively lightweight component so that the worst-case vibrations are less intense. Roughly speaking, practical systems are tuned to either move the main mode away from a troubling excitation frequency, or to add damping to a resonance that is difficult or expensive to damp directly. An example of the latter is a crankshaft torsional damper. Mass dampers are frequently implemented with a frictional or hydraulic component that turns mechanical kinetic energy into heat, like an automotive shock absorber. An electrical analogue is an LCR circuit.
Given a motor with mass {\displaystyle m_{1}} m_{1} attached via motor mounts to the ground, the motor vibrates as it operates and the soft motor mounts act as a parallel spring and damper, {\displaystyle k_{1}} k_{1} and {\displaystyle c_{1}} c_{1}. The force on the motor mounts is {\displaystyle F_{0}} F_{0}. In order to reduce the maximum force on the motor mounts as the motor operates over a range of speeds, a smaller mass, {\displaystyle m_{2}} m_{2}, is connected to {\displaystyle m_{1}} m_{1} by a spring and a damper, {\displaystyle k_{2}} k_{2} and {\displaystyle c_{2}} c_{2}. {\displaystyle F_{1}} F_{1} is the effective force on the motor due to its operation.
Production cars
Tuned mass dampers are widely used in production cars, typically on the crankshaft pulley to control torsional vibration and, more rarely, the bending modes of the crankshaft. They are also used on the driveline for gearwhine, and elsewhere for other noises or vibrations on the exhaust, body, suspension or anywhere else. Almost all modern cars will have one mass damper, some may have 10 or more.
The usual design of damper on the crankshaft consists of a thin band of rubber between the hub of the pulley and the outer rim. This device, often called a harmonic damper, is located on the other end of the crankshaft opposite of where the flywheel and the transmission is. An alternative design is the centrifugal pendulum absorber which is used to reduce the internal combustion engine's torsional vibrations on a few modern cars.
All four wheels of the Citroen 2cv incorporated a tuned mass damper (referred to as a "Batteur" in the original French) of very similar design to that used in the Renault F1 car, from the start of production in 1949 on all four wheels, before being removed from the rear and eventually the front wheels in the mid 1970s
Tuned mass dampers stabilize against violent motion caused by harmonic vibration. A tuned damper reduces the vibration of a system with a comparatively lightweight component so that the worst-case vibrations are less intense. Roughly speaking, practical systems are tuned to either move the main mode away from a troubling excitation frequency, or to add damping to a resonance that is difficult or expensive to damp directly. An example of the latter is a crankshaft torsional damper. Mass dampers are frequently implemented with a frictional or hydraulic component that turns mechanical kinetic energy into heat, like an automotive shock absorber. An electrical analogue is an LCR circuit.
Given a motor with mass {\displaystyle m_{1}} m_{1} attached via motor mounts to the ground, the motor vibrates as it operates and the soft motor mounts act as a parallel spring and damper, {\displaystyle k_{1}} k_{1} and {\displaystyle c_{1}} c_{1}. The force on the motor mounts is {\displaystyle F_{0}} F_{0}. In order to reduce the maximum force on the motor mounts as the motor operates over a range of speeds, a smaller mass, {\displaystyle m_{2}} m_{2}, is connected to {\displaystyle m_{1}} m_{1} by a spring and a damper, {\displaystyle k_{2}} k_{2} and {\displaystyle c_{2}} c_{2}. {\displaystyle F_{1}} F_{1} is the effective force on the motor due to its operation.
Production cars
Tuned mass dampers are widely used in production cars, typically on the crankshaft pulley to control torsional vibration and, more rarely, the bending modes of the crankshaft. They are also used on the driveline for gearwhine, and elsewhere for other noises or vibrations on the exhaust, body, suspension or anywhere else. Almost all modern cars will have one mass damper, some may have 10 or more.
The usual design of damper on the crankshaft consists of a thin band of rubber between the hub of the pulley and the outer rim. This device, often called a harmonic damper, is located on the other end of the crankshaft opposite of where the flywheel and the transmission is. An alternative design is the centrifugal pendulum absorber which is used to reduce the internal combustion engine's torsional vibrations on a few modern cars.
All four wheels of the Citroen 2cv incorporated a tuned mass damper (referred to as a "Batteur" in the original French) of very similar design to that used in the Renault F1 car, from the start of production in 1949 on all four wheels, before being removed from the rear and eventually the front wheels in the mid 1970s