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Materials like brass and steel have small damping capacities allowing vibration energy to be transmitted through them without attenuation. An example of a material with a large damping capacity is gray cast iron. [2] An understanding of this effect can be gained from observation of a stress-strain diagram with exaggerated features.
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
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 ...
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.
The energy consumed in manufacturing ductile iron pipe was 19.55 MJ per kg and volume of emissions released during manufacture was 1.430 kg CO 2 per kg, compared to 68.30 MJ per kg of energy and 4.860 kg CO 2 per kg emissions for PVC pipes, and 1.24 MJ per kg and 0.148 kg CO 2 per kg for concrete pipes of the same diameter.
More commonly, for crystalline materials with low damping, a pulse propagation method is used. This method employs a wave packet whose length is small compared to the specimen. The pulse is produced by a transducer at one end of the sample, and the velocity of the pulse is determined either by the time it takes to reach the end of the sample ...
In North America and the UK, pressure piping is usually specified by Nominal Pipe Size (NPS) and schedule (SCH). Pipe sizes are documented by a number of standards, including API 5L, ANSI/ASME B36.10M (Table 1) in the US, and BS 1600 and BS 1387 in the United Kingdom. Typically the pipe wall thickness is the controlled variable, and the Inside ...
Impact damping refers to only a single (somewhat larger) auxiliary mass in a cavity, whereas particle damping is used to imply multiple auxiliary masses of small size in a cavity. The principle behind particle damping is the removal of vibratory energy through losses that occur during impact of granular particles which move freely within the ...