Customized Rubber Parts for Extreme Environments: Materials and Design Considerations |

Abstract: The performance of rubber materials is severely challenged by extreme environments such as high temperature, low temperature, high pressure, corrosion and radiation. The material choice and structural design are critical to the manufacture of custom rubber parts for use in extreme environments. This article lays out the systematic analysis of how properties are affected due to the extreme environment and the selection of the rubber materials commonly used in the extreme environments, provides relevant considerations for the design tomake custom rubber parts, hoping to provide theoretical guidance and practical reference for the application of rubber parts in extreme environments.

Keywords: extreme environment, custom rubber products, material properties, structural design, reliability

Introduction

Excellent sealing, shock absorption, wear resistance and corrosion resistance, so that custom rubber parts widely used in aerospace, petrochemical, deep sea exploration, nuclear industry and other extreme environment fields. But extreme environmental factors greatly affect the performance of rubber materials so that rubber parts often have performance degradation and even failure. So, selecting an appropriate rubber material and implementing a sound structural design is the solution to make customized rubber parts run safely and reliably in extreme environments.

Collecting data on the properties of rubber material from a biosafe environment

The effect of extreme environment on rubber materials performance is multi-level and complex, mainly including the following aspects:

High temperature heat: the secondary erosion of rubber from high temperature accelerates the aging process of rubber materials, which will cause the hardness to increase, the tensile strength will decrease, the elongation at break will decrease, and even thermal decomposition leads to permanent deformation. On the other hand, high temperature can deteriorate the compressive performance and wear resistance of rubber materials.

This means very low temperature environment: Low temperature makes the rubber material glass transition, and lose elasticity, become brittle and hard, and impact strength decreased sharply. Excessively low temperature can cause the rubber parts to shrink, and it will also affect the sealing performance, and even lead to failure.

Under the action of pressure, rubber materials can occur volume compression, creep and stress relaxation, etc. At the upper end of pressure, seals can fail — for seals. Moreover, the high-pressure field is often accompanied by temperature change, which will also complicate the performance change of rubber materials.

Swelling and cracking of rubber materials or dissolution, decomposition, resulting in reduced mechanical properties and shorten life. FX: The performance of various rubber materials against corrosive media varies greatly.

Radiation environment: The high-energy rays (gamma rays, X-rays, etc.) are radiated to break, crosslink and oxidize rubber molecular chains, change the chemical structure and physical properties of rubber materials, and increase its hardness, increase brittleness, and decrease strength.

Rubber materials used in extreme environment.

It is also important to use rubber materials with corresponding tolerance to different extreme environments. Below is a list of a few of the most standard rubber materials used for extreme environments:

Fluorine rubber (FKM) : select high temperature resistance, oil resistance, chemical corrosion resistance of elastomer, can be used in the high temperature acid base and a variety of organic solvent environment for a long time. It is frequently used to produce seals, heat resistant tubes / parts, etc. But the low temperature resistance of fluorine rubber is not well.

Silicone rubber (VMQ): Silicone rubber has excellent high and low temperature resistance, electrical insulation and oxidation resistance, can still maintain good elastic in the temperature range of 60 ° C to 200 ° C. Used to be used to manufacture high temperature cable sheath, low temperature seals, etc. But, the mechanical strength of silicone rubber is not high, and the wear resistance is not good.

Hydrogenated nitrile butadiene rubber (HNBR): Hydrogenated nitrile butadiene rubber is hydrogenated on the basis of nitrile butadiene rubber, its heat resistance, oil resistance and ozone resistance are greatly improved. Applicable to manufacture automotive engine seals, oil drilling equipment etc.

Ethylene propylene rubber (EPDM): Ethylene propylene rubber has good ozone resistance, weather resistance, water resistance and chemical corrosion resistance, and can be made into outdoor rubber products. But it isn't resistant to oil and some solvents.

Perflurane rubber (FFKM): One of the most excellent rubber materials, with extreme high temperature resistance, chemical corrosion resistance and solvent resistance, can be used in extremely harsh environment for a long time. Its price is expensive, and it is appropriate for a situation where reliability is needed.

Tailoring rubber components in challenging applications: Critical design aspects

Besides the selection of the rubber material, a reasonable structure must be designed to guarantee the rubber parts can work reliably in such environment. Some design considerations to keep in mind:

Difference curve coordinates: Guarantee the accuracy of support coordinates and curvature radius coordinates, avoid stress concentration in large areas of rubber parts, and use rounded corner transition to minimize local stress concentration and improve the fatigue life coefficient of weapons rubber parts.

The deformation range is controlled: Rational design of the shape and size of the rubber parts, control the deformation range in the working process, avoid stretching or excessive compression, and extend the service life.

2 Optimize sealing structure: according to the different sealing application, shall be the right sealing structure, such as O-ring, Y-ring, rectangular ring, etc., so as to ensure the reliability of sealing performance. One should, however, take into account the effect of temperature change on the size of the seal.

In the design process of rubber medium, it is necessary to fully consider the compatibility of rubber with the contact medium to avoid the swelling, cracking or phosphorus of the material, and choose the appropriate contact area and contact mode.

Perform FEA: With the finite element simulation software, simulate the rubber/parts stress and strain distribution in the extreme environment, David engineers help optimize the structure design and improve product reliability.

Sufficient test verification: Sufficient test verification shall be conducted before practical application, including high temperature, low temperature, corrosion, aging and other tests, to verify that the rubber parts can satisfy the design requirements and reliability.

Conclusion

Customization demands that performance of a rubber part be able to hold up under extreme environments. It is the key to ensure the safe and reliable working of rubber parts in extreme environment by selecting suitable rubber materials and carrying out reasonable structural design. In the future, there will be more and more new materials emerging and design methods improving, customized rubber parts for extreme environment will be applied to more areas. At the same time, it needs to further study the aging mechanism and failure mode of rubber materials in extreme environment, in order to provide theoretical guidance for the design and application of rubber parts.