Contact Pressure and Strain Energy Density of Hyperelastic U-shaped Monolithic Seals under Axial and Radial Compressions in an Insulating Joint: A Numerical Study

Abstract

Abstract:In insulation joints, elastomeric U-shaped monolithic seals (UMSs) are replacing O-ring systems because of their enhanced sealing capabilities for the oil and gas industries. UMSs are compressed axially during assembly and radially when pressurized in operation. The reliability of UMSs due to the displacement imposed during assembly and the internal pressure in operation is influenced by the axial compression ratio, thickness ratio (TR), and geometric complexity. In this study, the hyperelastic behavior of elastomeric UMSs under axial and radial compressions is investigated using axisymmetric finite-element analysis. Twelve examples of UMSs with three geometric restraints (open grooves on both sides (type 1), an open groove on one side only (type 2), and no groove (type 3)) and four thickness ratios (TR = 0.25, 0.50, 1.00, and 1.50) are evaluated. To analyze nonlinear elastomeric materials, neo-Hookean constitutive equations are applied and the UMSs are considered as being a nearly incompressible hyperelastic material with a Poisson's ratio of 0.499. The failure and detachment risks of UMSs are analyzed in terms of the equivalent stress, gap distance, contact pressure, and strain energy density. It is advantageous that the smaller the TR, the smaller the stress distribution. However, the generation of broader detachment regions is observed. Type 1 symmetrically shows the lowest stress distribution and the smallest detachment region, whereas type 3 symmetrically shows the highest values. Type 3 (TR = 0.25) shows the broadest detachment region in the arc-length range from −15.7 to 15.7 mm, whereas the largest gap of 0.7 mm is observed in type 2 (TR = 0.5). For all types, the detachment region disappears completely at TR = 1.0 or higher, which implies that full sealing is occurring. The average contact pressure increases exponentially during axial compression (in assembly) and linearly during radial compression (in operation). The largest contact pressure of 31.5 MPa is observed in type 3 (TR = 1.5), while the lowest is observed in type 1 (TR = 0.25). As for the strain energy density, type 3 at TR = 0.25 shows the largest increase in the strain energy density with 1.75 MJ/m 3 , while type 1 shows the most stable values of all cases. In conclusion, the lowest risk of failure of a nonlinear hyperelastic UMS was investigated numerically with minor equivalent stress and detachment region with higher contact pressure, which can be taken into account to ensure the reliability of the UMS.

A design and optimization of a high throughput valve based microfluidic device for single cell compartmentalization and analysis

“…The von Mises stress failure criterion is related to strain energy density which tells the failure of the material once the distortional strain energy exceeds a critical value, which in turn depends on the design parameters 18 . The strain energy density function ( W ) or the stored energy density refers to the energy stored in the material per unit volume of the original geometry as a function of strain at that material point.…”

Design and Optimizations of a High-throughput Valve-based Microfluidic Device for Single Cell Compartmentalization and Analysis

“…The von Mises stress failure criterion is related to strain energy density which tells the failure of the material once the distortional strain energy exceeds a critical value, which in turn depends on the design parameters 20 . The strain energy density function (W) or the stored energy density refers to the energy stored in the material per unit volume of the original geometry as a function of strain at that material point.…”

Visco-Hyperelastic Model with Damage for Simulating Cyclic Thermoplastic Elastomers Behavior Applied to an Industrial Component

“…From the phenomenological hyperelastic models existing in the literature most of them can be classified among those defining the strain energy density as a scalar function of material properties and deformation invariants, and those using principal stretches instead [19,29].…”