Autoclave Upgrade for Corrosion Fatigue Testing

The objective of this project is to expand the University of Idaho’s current fatigue testing capabilities to include an autoclave load frame for use in fatigue testing of materials with a focus in metals to be used in nuclear power plants.

=Problem Definition=

Background
The objective of this project is to expand the University of Idaho’s current fatigue testing capabilities to include an autoclave load frame for use in fatigue testing of materials with a focus in metals to be used in nuclear power plants. Currently, no system is on hand to accomplish the fatigue testing desired by Dr. Stephens.

Deliverables
The scope of this project includes designing/purchasing all of the components for the fatigue testing apparatus, assembling it, and testing it for proper usability as defined in the following deliverables.

Initial Client Meeting & Expectations
The initial client meeting was conducted on June 14th, 2018. Dr. Stephens and Nicholas Schaber prepared the following list of "Primary Objectives" for the project.
 * Load Frame Upgrades
 * Loading system (motor/drive/gearbox, rated to &asymp;10 kips)
 * Load cell (coinciding with applied loads)
 * Load cell calibrated in line with seal
 * Load train displacement measurement (LVDT)
 * Extension rates up to 0.05 mm/s
 * Lid lifting/holding device
 * Load Control and Measurement
 * Feedback control loop (load controlled)
 * User interface for load frame
 * Programmable loading waveforms including:
 * Variable strain rate
 * Fatigue (cyclic loading, variable frequencies)
 * Creep-fatigue (variable hold time and set loading)
 * Constant load
 * Crack measurement/monitoring (DCPD)
 * User interface over/under warnings (temp, pressure, load)
 * Autoclave Upgrades
 * High temperature/pressure dynamic seal
 * Lid modifications
 * Loading rod
 * Internal load support
 * Isolated through-lid fittings for DCPD wires
 * Operating temperature of 400&deg;C (&asymp;750&deg;F)
 * Operating pressure of 20MPa (&asymp;3000psi)

Specifications
Acronyms used in this text:
 * UI:  User Interface
 * LVDT: Linear Variable Differential Transformer
 * DCPD: Direct Current Potential Drop

=Design Considerations=



=Project Learning= The autoclave load frame system being developed has many components, but the two requiring the most research and consideration are the Dynamic Seal and the Actuation System.

Dynamic Seal
With the design shown in Figure 1, a rod is moved linearly through the top of the autoclave pressure chamber. This requires a strong, Dynamic Seal to handle the movement of the rod while containing the required maximum temperature, pressure, and corrosive environment.

One of the seals considered is a Stuffing Box. According to Wikipedia, a stuffing box is an assembly which is used to house a gland seal. It is used to prevent leakage of fluid, such as water or steam, between sliding or turning parts of machine elements.
 * Advantages
 * Awesome
 * Cool
 * Disadvantages
 * Lame
 * Boring
 * Potential Source and Cost

Another option considered is a spring seal, which is a shaft seal with a Garter Spring contained within the seal to provide compression around the shaft and prevent leakage.
 * Advantages
 * Disadvantages
 * Potential Source and Cost
 * Disadvantages
 * Potential Source and Cost
 * Potential Source and Cost
 * Potential Source and Cost

The next seal considered is a Metal Bellows. Wikipedia defines metal bellows as elastic vessels that can be compressed when pressure is applied to the outside of the vessel, or extended under vacuum. When the pressure or vacuum is released, the bellows will return to its original shape (provided the material has not been stressed past its yield strength).
 * Advantages
 * Disadvantages
 * Potential Source and Cost
 * Disadvantages
 * Potential Source and Cost
 * Potential Source and Cost
 * Potential Source and Cost

Actuation System
Referring again to Figure 1, an Actuator System is needed to raise and lower the gripper arm attached to the test specimen. This system needs to be robust enough to provide the test loads required for fatigue testing of the specimen.

Potential Source and Cost
=Final Design=

=Validation=

=Team Members=

=Additional Documentation=

Project Schedule



Meeting Minutes

File:2018 AutoclaveExperts MeetingMinutes.pdf

Presentations



Client Interview

File:2018_AutoclaveExperts_QuestionsForClient.pdf