MODES (Modelling Of Decompression in Elastomeric Systems) is a successful project that has resulted in software that predicts explosive decompression (ED) in elastomer systems. It provides a cost efficient alternative to physical testing by allowing a company's engineers to assess an extensive range of 'what if...' scenarios.

Explosive Decompression Damage
Elastomer seal failure due to rapid depressurisation can cause problems within many industries such as oil and gas, chemical or automotive. Failure is often insidious and progressive taking the form of cracks, blisters and gross deformations or in some cases producing immediate catastrophic fragmentation and severe leakage. Failure of inexpensive elastomeric seals can lead to loss of containment and potentially to whole fields or systems closing down. The MODES project is predicting the onset of ED damage in seals, enabling the design of components and operating procedures to avoid failure.

MODES Results

• Understanding ED and the relationship of seal manufacturing processes
• Prediction of ED using a new methodology that combines material testing and finite element analysis
• Over 88% accuracy for prediction of ED damage in elastomer O-rings subjected to multiple decompressions

MODES provides an extremely reliable prediction of explosive decompression damage for the materials in the database. The modelling software is available to each sponsor and contains extensive data on the selected materials.

The new phase, MODES 4, launched in June 2005, will review and refine the finite element modelling approach to elucidate the mechanisms and physical models of how the best elastomers work.

This exciting model refinement will aim to incorporate the latest proven hyperelastic strain energy functions and to investigate developments in elastomer fracture mechanics to improve the capturing of the physical behaviour of the material within the finite element stress model.

The programme has collected a wealth of material data and experience in the field and this revisiting of the early modelling will bring all that knowledge to bear, to produce an invaluable tool for the end user to predict the decompression resistance of commercial compounds, and for commercial elastomer formulators to understand the influence of elastomer composition on decompression performance.

Please contact us for more details.

The MODES Software
Currently MODES can be used to determine:

• The safe minimum decompression time
• The number of decompression cycles the seal can survive without damage
• Seal performance under user-specified conditions

MODES enables users to:

• Optimise seal and housing design
• Perform a sensitivity study on material variability and material type
• Assess the effect of different fluids, pressures, and temperatures

Benefits to Seal Users and Manufacturers

• Prevention of hazardous environmental incidents
• System design to avoid ED damage
• Prediction of damage onset
• Understanding of damage process
• Risk analysis
• Maintenance planning
• Material database
• Materials recommendation
• Validated test procedures

Benefits to Seal suppliers

• Extended market opportunities
• Close involvement with operators
• QC/QA guidance
• Exposure of products to end users