Pranab Kumar Bhattacharyya
Founder – AI Chat Rubber Polymers, Pune, Maharashtra, India
Introduction
Rubber is an elastic, extensible, and flexible solid material characterized by its ability of extending many of the times of its original length even under the effect of a weak force and of rapidly returning nearly to their original dimensions and shape when the external force is removed. Rubber Composed of long flexible molecules, undergo reversible deformation like plastics under controlled (not so large) deformation and narrow temperature interval for a short period of time. However, if the deformation is large and stay for longer period and at elevated temperature then it becomes irreversible. Rubber is widely used as an engineering material in applications such as resilient mountings, vibration isolators, dampers, and impact pads. These applications often require precise control over the material’s stiffness characteristics, both static and dynamic. To ensure optimal performance, appropriate test specifications must be established.
A static test is only “static” in that the load application comes to rest before the measurement is taken or the rate of deflection does not normally exceed 0.8mm/s (2 in./min.). Typically, such tests place the rubber in shear or compression. There are several methods to specify static load deflection characteristics, ensuring the rubber performs effectively under the expected static conditions.
For applications like vibration isolators, the behavior of rubber under dynamic conditions is crucial. Rubber exhibits greater stiffness dynamically than statically. Because the ratio of static to dynamic stiffness varies among different rubber compounds, specifying the dynamic characteristics is often necessary. Various methods exist for dynamic testing, each aimed at understanding how rubber will perform under the operational conditions it will face. Understanding the factors that influence both static and dynamic load deflection characteristics is essential. These factors ensure that rubber components perform reliably in their intended applications, providing the desired levels of resilience, vibration isolation, damping, and impact resistance. By carefully considering and specifying the appropriate static and dynamic characteristics, engineers can ensure that rubber components meet the functional requirements of their applications. Materials that possess typical rubber like viscoelastic properties are also known as Elastomers.
To define the scope of this chapter the following contents have been covered mostly with data and chart and compounding guideline.
- Understanding Dynamic Properties of Rubber and their influences
- Significance of Hysteresis Loop and energy absorption
- Resilience & Heat Buildup of general-purpose rubber
- Temperature dependence Rebound Resilience of EPDM rubber
- Importance of tangent delta (Damping Factor) for service in static and dynamic application.
- Frequency and temperature dependence of Damping factor of Natural and Neoprene Rubber.
- Factors effecting static and dynamic load characteristics
- Compressor Grommets: Dynamic and service property requirements and basis of compounding for noise isolation based on EPDM rubber.
- Bridge bearing: Dynamic and service property requirements and basis of compounding for vibration isolation, based on NR and CR.
- Shock absorbers and silent blocks: Dynamic and service property requirements and basis of compounding for Shock absorption, based on NBR rubber.
Disclaimer
The chapter author, and AI Chat Rubber Polymers are not responsible for the use or accuracy of information in this chapter, such as applications and properties
(The complete chapter is available in member’s area)
