Vibration and Viscoelasticity of NonBuren Anti-vibration Material

About Vibration

Vibration and shock isolation can be classified into two categories.

1. Active Applications
   This involves preventing the transmission of vibrational or shock forces from machinery operations to the foundation. This is mainly achieved by placing anti-vibration materials, such as under vacuum pumps, to reduce the impact on surrounding areas.
2. Passive Applications
   Thisinvolves preventing vibrations or shock movements from the foundation, caused by external sources, from being transmitted to machinery. This is also referred to as vibration isolation. It is mainly used in applications such as microscopes and inspection equipment.

About Elasticity

There are two types of elasticity: rubber elasticity (entropic elasticity) and crystalline elasticity (enthalpic elasticity).

1. Rubber Elasticity (Entropy Elasticity)
   This refers to the ability to absorb external forces and store them as energy, which can then be released to return the material to its original shape. Rubber is an example of this.
2. Crystalline Elasticity (Enthalpy Elasticity)
   This refers to elasticity where energy cannot be stored, leading to plastic deformation or breakage. Metals are an example of this.

About Viscoelasticity

When it comes to polymer materials, viscoelasticity can be modeled by combining elements of elasticity and viscosity. Elasticity is represented by a spring, and viscosity by a dashpot.

This means that in addition to the spring constant, a constant representing the viscous element is also necessary. Solids exhibit elasticity, while fluids exhibit viscosity. Materials like NonBuren possess both properties.

Stress σ = Eε (E: Elastic element (spring constant), ε: Strain)
Stress σ = ηε' (η: Viscous element, ε': Strain rate (differential of strain))

In simple terms, the more you compress a spring, the more force is applied. A dashpot, on the other hand, applies more force the faster you push it. If it’s fluid-like, you can easily press it, but if it’s sticky, the faster you try to press it, the more resistance you feel.

The combination of these elements leads to models like the Maxwell (series) model or the Voigt (parallel) model, which are fundamental when modeling real-world phenomena.

How to Select Anti-Vibration Materials (About Spring Constants)

Series and Parallel Connection of Springs

Series Connection:

Parallel Connection:

The above equations apply in each case.

When combining materials of the same type, the following equation generally applies.

Where \(K\) is the spring constant, \(S\) is the cross-sectional area and \(l\) is the length. This means the spring constant is proportional to the cross-sectional area and inversely proportional to the length.

How to Select Anti-Vibration Materials

From this, it can be understood that when supporting a heavier object with Anti-Vibration materials like NonBuren, either the cross-sectional area should be increased or the hardness should be increased to raise the spring constant. The appropriate load is determined by the balance between cross-sectional area and hardness, so please consider this balance when selecting materials.

Precautions (Handling Instructions)

Precautions When Installing Anti-Vibration Rubber

1. Ensure that the deformation of each part is uniform during installation.
2. Do not install the anti-vibration rubber in a way that causes abnormal deformation.
   Abnormal deformation refers to situations such as:
   1. No tension or excessive compression beyond the design limits on the anti-vibration rubber. Installing in a way that causes abnormal compression or tension due to misalignment or curvature of the mounting part, as shown in Figure 1.
   2. Do not install anti-vibration rubber in a twisted or sheared condition, as shown in Figures 2 and 3.

Usage Precautions

1. Follow the precautions for storage and transportation.
2. Do not exceed the allowable load during use.
3. Avoid contact with solvents
4. Ensure that the surrounding temperature and transmitted heat do not exceed 70°C during use.
5. Make sure to conduct regular inspections and check for any abnormalities. (such as separation between the rubber and metal parts, rubber damage, corrosion, or deformation of metal parts).

Precautions for Storeage and Transportation of Anti-Vibration Rubber

1. Store in a cool, dark place with little airflow, avoiding direct sunlight.
2. Maintain storage and transportation temperatures at around 40°C or below.
3. Avoid contact with solvents.
4. Do not store in places with high ozone concentrations.
5. Ensure that the rubber does not undergo abnormal deformation due to excessive loading.
6. Take care to prevent damage from external forces.
7. Avoid long-term storage as much as possible.

Replacement of Anti-Vibration Rubber

1. Cracks in the rubber.
2. Separation between the rubber and metal parts.
3. Deformation of the rubber (if the deformation progresses beyond the initial state and exceeds 20% of the rubber thickness).
4. Swelling of the rubber due to solvents.