Materials Joining Engineering Projects

In addition to their capstone senior design and other class projects, LeTourneau MJE students have a unique opportunity to conduct materials joining research and development where graduate students and undergraduates work together, most of which is sponsored by the same companies that hire our graduates.  The critical thinking, problem-solving and project management skills that are developed in the applied research environment, as well as the self-direction, inquisitiveness and creativity that it fosters, make our graduates especially attractive in the career marketplace.  While there are certain commonalities between Senior Capstone Design projects and R&D, research is aimed at applied scientific aspects of each work and at finding new knowledge. On the other hand, the Capstone Design deals with making new devices, validating new designs and supporting the practical aspects of R&D. Below are a few examples. Here is a link to the Senior Design project page.

Thermoelectric Element Joining 

 The II-VI Foundation awarded a second year, $69,775 in external funding in May 2011 to the Materials Joining Engineering program at LETU for continuation of Thermoelectric Element joining research and development. This stage of research is titled “Microwave Welding of Bismuth- and Lead- Telluride Semiconductors” and brings a novel approach to joining by using both Dielectric and Eddy Current heating using microwave frequencies. The ultimate goal of the work is to increase the efficiency of thermoelectric modules, which have the potential of being safe, sustainable and maintenance-free electrical power sources for waste heat reclamation.

One such an example is BMW’s 521 Series TE generator attached to the exhaust pipe which charges ~10% of the electricity needed to the batteries. These solid state devices use the Seebeck effect to generate electricity from the temperature differential between the cold and hot side of the elements.

 Among limiting factors in the current low efficiency of these thermoelectric devices is the joining technology (mostly soldering) used for manufacturing modules. The ability to use welding processes (laser, ultrasonic, microwave) that work above the melting temperature of solder could potentially increase the Figure of Merit of welded TE modules to 15%.

The supporting Senior Design project can be found at:
Prof. Yoni Adonyi is the Principal Investigator, while Associate Prof. Robert Warke and Assistant Prof. Seung Kim are co-investigators in different areas of Materials Science and Electrical Engineering involved in the research.

Innovative Welding Technologies for Bridge Steels: 

 Following 15 years of weldability research on the hydrogen induced cracking susceptibility of High Performance Steels having 70 ksi yield strength, the MJE program at LETU was entrusted with a new, two-year $330,000 R&D project funded by the Federal Highway Administration (FHWA) Research Labs from McLean, VA. 

The numerical modeling and experimental work is aimed at finding innovative welding technologies to replace fusion welding Fracture Critical Members or FCM in modern bridges.   Properties of dissimilar combinations of high strength and corrosion resistant steels will be investigated.  Of particular interest is improving the tool life when using Friction Stir Welding in steels (so far, the most successful applications of FSW were in welding Aluminum and other light alloys).

The welding processes and subcontractors involved are: Friction Stir Welding (FSW) at the Navy Surface Warfare Center (Carderock, MD), High Frequency (HF) at Thermatool Corp and the currently developed hybrid HF/FSW processes at LETU. One more innovation is the recently patented Thermal Stir Welding process by NASA Marshall Space Center (Huntsville, Al). 
Visit the Senior Design project for Hybrid Friction Stir Welding.
Neither of these four solid-state processes involve melting of the metal during welding, and they show promise in improving toughness in the weld Heat Affected Zone or HAZ, when compared to fusion welding. While $220,000 will end up at LETU for the research lead by Prof. Yoni Adonyi and the rest will be paid to the subcontractors, this still is a significant recognition of LETU’s expertise in the area of welding HPS steels by receiving the lead as well as the final evaluator’s role in the project.