Design of Test Setup to Measure Shear Strength of Polymers at Elevated Temperatures

Photo of Meena Alavi, Lauren Burns, and Patricia Rodriguez Students: Meena Alavi, Lauren Burns, and Patricia Rodriguez

Sponsor: Schlumberger

Date: Fall 2011

Requirements:
The improved test stand is required to withstand temperatures up to 200°C because the O-rings and disks are tested between 25°C and 200°C. To provide more consistent results, the new stand also must have an automated source of force, rather than the previous hydraulic hand pump, . Safety was another requirement during design and experimentation as the team was dealing with high temperatures and pressures. Cost was another limitation as team wanted to produce the best cost effective solution.

Problem:
Schlumberger uses O-rings and thermoplastic disks to seal electric equipment that they use deep below the earth in drilling operations. These materials fail by shearing under high temperatures and pressures, and Schlumberger has no way to test the shear strength of these materials. The design team's goal this semester was to modify a previous team's test stand that shears O-rings both longitudinally and axially. This included developing a new attachment to test thermoplastic disks, automating the current stand, and decreasing the difference between the axial and longitudinal O-ring experimental shearing data.

Solution:
The team delivered to the sponsor a newly reinforced test stand with three attachments to shear thermoplastic disks and O-rings (axially and longitudinally). The hydraulic hand pump was replaced with a hydraulic power unit and the longitudinal cutter was redesigned to obtain more consistent results between the longitudinal and axial O-ring tests. For the disk tests, materials from two different suppliers were tested to provide the sponsor with data on which material and brand had the higher shear strength. The sponsor not only gained a way to test polymeric materials, but they received sets of experimental data. This test stand and analysis will help Schlumberger understand failure modes and reduce costs due to inactivity.

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