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Damping capacity is a mechanical property of materials that measure a material's ability to dissipate elastic strain energy during mechanical vibration or wave propagation. When ranked according to damping capacity, materials may be roughly categorized as either high- or low-damping.
The damping ratio provides a mathematical means of expressing the level of damping in a system relative to critical damping. For a damped harmonic oscillator with mass m , damping coefficient c , and spring constant k , it can be defined as the ratio of the damping coefficient in the system's differential equation to the critical damping ...
Anelasticity is therefore by the existence of a part of time dependent reaction, in addition to the elastic one in the material considered. It is also usually a very small fraction of the total response and so, in this sense, the usual meaning of "anelasticity" as "without elasticity" is improper in a physical sense.
Relative damping capacity of various metals [15] Materials Damping capacity † Gray iron (high carbon equivalent) 100–500 Gray iron (low carbon equivalent) 20–100 Ductile iron: 5–20 Malleable iron: 8–15 White iron: 2–4 Steel: 4 Aluminum: 0.47 † Natural log of the ratio of successive amplitudes
Damping dissipates energy in the system, which reduces the vibration level which is transmitted at the natural frequency. The fluid in automotive shock absorbers is a kind of damper, as is the inherent damping in elastomeric (rubber) engine mounts. Damping is used in passive isolators to reduce the amount of amplification at the natural frequency.
The ratio of the loss modulus to storage modulus in a viscoelastic material is defined as the , (cf. loss tangent), which provides a measure of damping in the material. tan δ {\displaystyle \tan \delta } can also be visualized as the tangent of the phase angle ( δ {\displaystyle \delta } ) between the storage and loss modulus.
Classic model used for deriving the equations of a mass spring damper model. The mass-spring-damper model consists of discrete mass nodes distributed throughout an object and interconnected via a network of springs and dampers.
The earliest study of thermoelastic damping can be found in Clarence Zener’s classical work, [1] [2] in 1937, in which he studied thermoelastic damping in beams undergoing flexural vibrations. Flexural vibrations cause alternating tensile and compressive strains to build up on opposite sides of the neutral axis leading to a thermal imbalance.