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Damping materials in mechanics and construction: Ideas, applications and advantages

Damping

Damping materials are essential in mechanics and construction. They are used to dampen the impact of shocks and vibrations and to improve the operation of machines and systems. They can be used in different mechanical and technical applications due to their unique properties. This article describes different types of damping and elastic materials, as well as their use in mechanics and construction. This article deals with different types of damping materials, their uses in mechanical applications and their specific properties.

Why are damping materials useful in mechanics?

Damping materials can be used in mechanics as vibration dampers to reduce vibrations, shocks and/or noise generated by mechanical systems such as engines, transmissions and other components. Reducing vibration and noise from mechanical systems improves overall system performance, reliability and safety. Effective damping of your system optimises the properties of your application and reduces the risk of damage or failure. As the use of damping materials minimises the material stress caused by vibrations, they significantly increase the service life of a mechanical system.

Types of damping materials

Different types of damping material are available that can be used efficiently in mechanics and construction. These include polyurethanes, elastomers and foams. Each material has its own specific properties, which must be evaluated for the respective application and the possible solutions. The choice of damping material depends on the specific requirements of the system, such as the frequency or the intensity of the vibration.

Polyurethane rubber

Polyurethane rubber is highly effective at dampening vibrations. It has excellent mechanical strength and is particularly resistant in combination with the high abrasion resistance. As polyurethane rubber has extensive vibration damping properties, it effectively cushions vibrations and absorbs the energy generated. It also has excellent resistance to oil and is primarily suitable for use in dry and chemical-free environments. Particularly heat-resistant, anti-static or abrasion-resistant forms of polyurethane rubber can be used depending on the area of application.

Polyurethane rubber

Properties of polyurethane
Designation Unit Polyurethane rubber
Standard Vulkollan® Abrasion-resistant Ceramic polyurethane rubber Heat-resistant Low rebound Very soft
Hardness Shore A 95 90 70 50 30 92 68 90 70 95 90 70 50 90 70 15
Specific gravity g/cm³ 1.13 1.13 1.20 1.20 1.20 1.26 1.20 1.13 1.13 1.2 1.15 1.13 1.03 1.02
Tensile strength MPa 44 27 56 47 27 45.5 60 44.6 31.3 42 26 53 45 44.6 11.8 0.6
Elongation % 380 470 720 520 600 690 650 530 650 360 440 680 490 530 250 445
Heat stability up to °C 70 80 (short-term 120) 70 70 120 70 80
Low temperature resistance up to °C -40 -20 -20 -20 -40 -20 -20 -20 -40
Note: The characteristic values for tensile strength and elongation are measured according to JIS standard K6251.

Elastomers

Elastomers are used in a large number of mechanical applications. Elastomers commonly used in industrial applications are:

  • Nitrile rubber (NBR)
  • Chloroprene rubber (CR)
  • Ethylene rubber (EPDM)
  • Butyl rubber (IIR)
  • Fluorinated rubber (FPM)
  • Silicone rubber (SI)
  • Hard rubber
  • Natural rubber (NR)

Elastomers are extremely versatile and can be used in different versions for a wide range of applications. Elastomers generally have a pronounced damping effect and can therefore withstand even strong vibrations and shocks. The material has particularly chemical- and temperature-resistant properties depending on the type of rubber used and can be used in applications requiring a high degree of shock absorption.

Properties of caoutchouc
Designation Unit Nitrile rubber (NBR) Chloroprene rubber (CR) Ethylene rubber (EPDM) Butyl rubber (IIR) Fluororubber (FPM) Silicone rubber (SI) Hard rubber (Hanenaito®) Natural Rubber (NR)
Standard High-strength version
Hardness Shore A 70 50 65 65 65 80 60 70 50 50 57 32 45
Specific gravity g/cm³ 1.60 1.30 1.60 1.20 1.50 1.80 1.90 1.20 1.20 1.30 1.20 0.90
Tensile strength MPa 12.7 4.4 13.3 12.8 7.5 12.5 10.8 7.4 8.8 7.8 8.3 10.3 16.1
Elongation % 370 400 460 490 380 330 270 300 330 400 810 840 730
Max. Operating temperature °C 90 99 100 120 120 230 200 200 60 70
Temperature for continuous use °C 80 80 80 80 210 150 150 30 70
Low temperature resistance up to °C -10 -35 -40 -30 -10 -70 -50 10 0
Note: The characteristic values for tensile strength and elongation are measured according to JIS standard K6251.

Foams

Foams can effectively dampen vibrations by absorbing the energy of the vibration across a variety of individual pores. They are very flexible and can also be applied to uneven or curved surfaces. They have good elasticity and, due to their porosity and low weight, can be used in a variety of ways to minimise vibrations and dampen noise. Another advantage of foams is the wide frequency range in which they can absorb vibrations.

Why are shock absorbers used in the field of mechanics?

Shock absorbers are used in mechanics to reduce or dampen the movement of an object or system. They can also prevent delays that can result in vibrations and oscillations in mechanical systems. Shock absorbers are frequently used in mechanical systems to absorb shocks and dampen the speed of moving objects in the event of a change in direction or impact. Frequently used for damping hydraulic systems (e.g. oil), achieving a compact design and robust operating characteristics.

In this data sheet, MISUMI shows an application example for "shock absorbers in mechanics".

How damping characteristics affect your application

Damping characteristics are an important factor for selecting the right shock absorber for an application. This characteristic describes the behaviour of the damper depending on the speed and deflection of the moving object.

There are different types of damping characteristics which are determined by the size, number and arrangement of the openings between the pressure chamber and the pressure accumulator inside the shock absorber.

Damper, classification according to damping characteristics

Damper, classification according to the damping characteristics
Structure Execution by prefabricated force Description
One opening S-design
Type A
Type B
Type L		 Type A, B, L A single hole design has the same resistance properties as a slotted design with space between the piston and cylinder, a single pipe design with an opening in the piston, or a double pipe design and one single opening.
A piston with one opening runs in an oil-filled cylinder. Since the opening area is the same throughout the stroke, the resistance is greatest immediately after an impact and then decreases evenly throughout the rest of the stroke.		 Graph
Multiple irregular openings Medium speed Type A, B, L In this double pipe design, the piston runs in the inner pipe. This inner pipe has several openings in the direction of lift and not only constant energy, but also energy from different sources can be absorbed. Designed for the absorption of kinetic energy during the first half of the stroke and regulation of the speed during the second half. Therefore, it is well suited for the absorption of energy in connection with air cylinders. Graph
Multiple openings High speed
H-design		 H-design In this double pipe design, the piston runs in the inner pipe. It has several openings in the direction of lift. Since the openings slowly become smaller at a decreasing lifting speed, the resistance remains relatively constant, even if it is slightly wave-like. Graph

How do you select the right shock absorber for your application?

When selecting the right shock absorber for an application, other factors must be considered in addition to the damping characteristics in order to achieve an optimal damping effect. The following calculations and tests must be carried out to determine the right shock absorber for your application:

  • Calculation of inertial energy
  • Calculation of temporary damper stroke
  • Calculation of excess energy
  • Calculation of total energy
  • Checking the maximum equivalent mass
  • Selection of damping characteristics
  • Checking the maximum energy consumed per minute

The choice of shock absorber depends on the application. High speed applications, for example, require shock absorbers with higher damping capacity.

Temperature and ambient conditions must also be taken into account to achieve optimal performance. Careful selection and installation of shock absorbers can help prolong the service life of mechanical systems and minimise noise and vibration.

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Product overview in the MISUMI catalogue