Mechanical Engineering

doctor ali beheshti running tribological experiments

COLLABORATION HOPES TO INCREASE EFFICIENCY IN MECHANICAL REACTORS

In collaboration with Texas A&M and Purdue University, Dr. Ali Beheshti, Assistant Professor in the Department of Mechanical Engineering, has been granted $773,000 ($165,000 for Lamar) funding support from Department of Energy to study tribological performance of Nickel alloys under a helium environment. The results of this project will enhance very high-temperature gas cooled reactors efficiency through obtaining basic/fundamental knowledge of failure mechanisms and tribological response in high temperature materials as well as developing predictive models. The project is expected to run through October 2019.

“Tribology is the science of interacting surfaces in relative motion dealing with the study of friction, wear and lubrication from nano to micro and macroscales,” says Beheshti, who has been assigned the modeling portion of the project and hopes evaluate the tribological response of Nickel alloys at operating temperatures that can exceed 700-950oC (1292o-1742oF) and establish predictive models. Beheshti’s team (Multiscale Tribology and Contact Mechanics Group) will focus on comprehensive multiscale numerical modeling to investigate and compare friction, surface damage and contact response of high temperature contacting pair materials in atmospheric condition and helium environments.

Operation at high temperatures is critical for power plants and nuclear reactors, resulting in substantial thermal efficiency. Materials that can withstand high temperatures and harsh environments are necessary for reliable and effective nuclear reactor operation. Nickel alloys are the principle candidates in high/very high temperature gas cooled reactors with outlet temperatures of 700-950°C. Therefore, understanding and optimizing mechanical and tribological response of high-temperature materials, particularly Nickel alloys, used in very high-temperature gas cooled reactors is crucial to increase durability, operational reliability, decrease exchange cost and understanding thermal effects on mechanical response.

“Our modeling concentrates on hot nano-indentation/scratch to estimate mechanical properties of the bulk material and potential thin oxide film. In addition, novel modeling of friction considering surface nano/micro features, creep and temperature fluctuations will be performed,” says Beheshti.

“By September 2019, we hope to find fundamental knowledge of failure mechanisms, and identify a tribological response in these materials and establish predictive models,” says Beheshti. Specifically, knowledge of friction coefficient behavior, surface wear, fretting, and self-welding leading to interface failures, as a function of aging time, dwell time, temperature, speed, load, gas composition, and surface roughness will be established for each material pair in the presence of air, helium and helium with impurities. In addition, this research hopes to uncover and suggest alternative solutions to mitigate tribological problems with Nickel alloys under high and very high temperature gas cooled reactors conditions by investigating different practical approaches such as optimizing design, operating conditions, and surface modifications. The successful fulfillment of this project promotes an improved, safer design of high and very high temperature gas cooled reactors.

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