INL Glovebox Tensile Testing System

The goal of this project is to create a small-scale tensile testing system for Idaho National Laboratory with the capability to perform high-temperature tests that can be easily installed in a glovebox.

Background
Idaho National Laboratory is currently researching a Uranium-Plutonium-Zirconium alloy as a potential solid fuel for nuclear reactors. While some testing has already been done, there is still much more to learn, particularly about the mechanical properties of the alloys. Due to its radioactive nature, any test performed on the U-Pu-Zr alloy must be done in a glovebox for safety, hence the need for a glovebox-based tensile tester. Our machine will enable INL to further their knowledge of this alloy and its potential usefulness. There are many models of tensile tester that already exist, but none meet the requirements set by INL. Many of these machines, especially those with the capability to perform high-temperature tests, are much too large and complex to be used in a glovebox. The models that are small enough are designed for much smaller loads than required for this device and cannot heat testing samples.

Deliverables
At the end of this project, we will have a functional tensile testing device that meets the requirements of INL. We will also create detailed instructions for the assembly of the device inside the glovebox, as well as usage instructions for performing tests and operating the heater.

Requirements
In addition to these, there were some more qualitative requirements. The device had to:
 * Provide accurate data regarding sample extension and applied force
 * Be capable of running a test from outside the glovebox after initial setup of sample and heater elements
 * Contain all external electronic components and controls in one location, ideally with a control panel for the ease of the user
 * Be visually appealing. While not a hard constraint, we wanted our machine to look more like a finished product than a rough prototype. We did this through painting and using a box to manage electrical systems

Design Considerations
The main limitation of the glovebox is a size constraint. Not only is there limited space inside the glovebox, but whatever we design has to fit through an 8” diameter hole so that researchers at INL can install it in the glovebox. On top of that, the system must be able to perform high temperature tests up to 700 C. Due to the radiation inside the glovebox, as many of the electronic components need to be outside as possible. The glovebox does have passthroughs that enable this. For the safety of the user, no external surface can exceed 50C, so some form of insulation will be needed around the heating chamber.

Tensile Testing
Tensile testing is used to measure certain mechanical properties of a material. The test is performed by pulling on a sample until it fractures and measuring the sample’s behavior. Measured data from the test is then used to generate a stress-strain curve. There are numerous properties that can be found through tensile testing. The first is a stress-strain curve, which plots the relationship between the stress and strain in a sample during the test. The stress is a measure of the force applied over the cross-sectional area of the sample ($$\sigma=\frac{F}{A}$$). The strain measures how far the sample elongates during the test relative to its original length ($$\epsilon=\frac{\Delta L}{L_0}$$). The linear portion of the graph is known as the elastic region, in which the material will return to its original shape after the load is removed. The slope of this line is known as Young’s Modulus. Past the yield strength, any deformation is permanent. Also of note is the ultimate tensile strength (UTS), which is the maximum stress that material can withstand. Finally, the fracture stress is the point at which the sample breaks.



Additional Documentation
Project Schedule

Fits Like a Glove Gantt Chart

Meeting Minutes

[Fits Like a Glove Meeting Minutes Document]

Presentations