Elastomer and rubber have been used in lots of industry applications, such as BOP/RCD packing elements, O-ring and other elastomeric seals, and other
elastomer components (bumper, vibration isolator, and etc). In most of the elastomer applications, the rubber/elastomer is molded with metal or other rigid materials.
FEA has helped the designers to achieve accurate analysis of the elastomer. However, due to the nonlinearity of elastomer and the extreme large deformation
as well as the composite structure, complex boundary conditions and contact, it is challenged to perform the analysis correctly and accurately.
Advanced understanding in nonlinear mechanics, hyper-elasticity, finite element method, with strong skills on FEA software are required for proper modeling and analysis of
elastomers and result interpretation. Tau Engineering has years' of both research and industry expierence in properties and applications of elastomers. Tau Engineering is
experienced in the following areas about elastomer
To obtain accurate results, several material test need to be performed to determine the material parameters. The uniaxial tension, biaxial tension, planar shear, simple shear tests, and volumetric test are normally required. For high temperature application, viscoelastic stress relaxation test may also need to be done. Tau Engineering is familiar with various material hyper-elastic model, and is able select the most appropriate model based on the material test data.
- BOP annular packing element design
- RCD passive packing element design
- other elastomer component design
- Nonlinear elastomer constitute model development
- FE code development and implementation
To obtain accurate results, several material test need to be performed to determine the material parameters. The uniaxial tension, biaxial tension, planar shear, simple shear tests, and volumetric test are normally required. For high temperature application, viscoelastic stress relaxation test may also need to be done. Tau Engineering is familiar with various material hyper-elastic model, and is able select the most appropriate model based on the material test data.
BOP Annular Elastomer Packing Element
The annular packing element is used in conventional BOP or modern managed pressure drilling (MPD) and riser gas handling (RGH) to shut off a well, when a kick is detected.
It is molded by rubber/elastomer with specially shaped wedges of metal fingers distributed at equal radial distance from each other within the elastomeric body.
The packing
element is able to seal off the well by hydraulic force. This causes the elastomer to flow inward towards the radial center. The elastomer need to undergo extreme nonlinear
defomration to achieve the sealing. For example, when a packing element is compressed into the closed position to seal about drillpipe, the elastomeric body of the packing
element may experience strains in excess of 300% in the area of the strain contrations. Furthermore, in a case where no drillpipe is present, the packing element may experience
strains of about 400-450%. These elevated strain, especially when repetitively and cyclically, may lead to the ultimate failure of the packing element.
The nonlinearity and large deformation need careful meshing and preprocess to ensure an accurate analysis results. Tau Engineering has
successfuly design and deployed BOP annular packing element in several RGH systems. Tau Engineering's skills in FEA and research experience in elastomer have helped
to model and analyze the packing elements in a proper and effective way.
The packing
element is able to seal off the well by hydraulic force. This causes the elastomer to flow inward towards the radial center. The elastomer need to undergo extreme nonlinear
defomration to achieve the sealing. For example, when a packing element is compressed into the closed position to seal about drillpipe, the elastomeric body of the packing
element may experience strains in excess of 300% in the area of the strain contrations. Furthermore, in a case where no drillpipe is present, the packing element may experience
strains of about 400-450%. These elevated strain, especially when repetitively and cyclically, may lead to the ultimate failure of the packing element.
The nonlinearity and large deformation need careful meshing and preprocess to ensure an accurate analysis results. Tau Engineering has
successfuly design and deployed BOP annular packing element in several RGH systems. Tau Engineering's skills in FEA and research experience in elastomer have helped
to model and analyze the packing elements in a proper and effective way.
RCD or other Passive Packing Element
Passive packing elements are integrated components in rotating control devices (RCDs) and other managed pressure drilling (MPD) or riser gas handling (RGH) devices to isolate the annulus.
Like BOP annular packing element, the seals conventionally have a metal insert or frame which provides strength, rigidity and installtion. Unlike BOP annular packing element which
is actively actuated, RCD packing element is passive. Therefore, the seal element must be flexible enough to allow pipe and tool joints to pass through the RCD while maintaining a seal around the drill pipe.
This results in different design conditions for passive packing element, e.g., wellbore pressure exerting on the sealing element, tool joints passing throught sealing element,
drillpipe/tooljoint rotating around the seal element. These conditions make the design of the passive packing element also very complicated. Example of Tau Engineering's design and analysis
is as follows.
Like BOP annular packing element, the seals conventionally have a metal insert or frame which provides strength, rigidity and installtion. Unlike BOP annular packing element which
is actively actuated, RCD packing element is passive. Therefore, the seal element must be flexible enough to allow pipe and tool joints to pass through the RCD while maintaining a seal around the drill pipe.
This results in different design conditions for passive packing element, e.g., wellbore pressure exerting on the sealing element, tool joints passing throught sealing element,
drillpipe/tooljoint rotating around the seal element. These conditions make the design of the passive packing element also very complicated. Example of Tau Engineering's design and analysis
is as follows.
O-ring/other Elastomeric seals
FEA is also important in modern design of O-ring and other elstomeric seals. The linear elastic properties were used to design and analyze O-ring
and other simple seal structure convertionally. However, modern design requires nonlinear FEA considering nonlinear material properties, contact,
viscoelasticity, and hysteresis.
Other Elastomeric/metal Components
A widespread use of rubber is for shock/vibration isolation and noise suppression in different industry, such as vehicles, machinery and buildings.
These applications takes advantage of well-known characteristics of rubber, i.e., energy absorption, damping, flexibility, resilience, long service life,
and moldability. These rubber/elastomer components requires dynamic analysis and quasi-static analysis to design an optimized structure.
