GRI Newsletter

The Board of Trustees, at their September 2009 meeting, decided to undertake a campaign to enlist members to the Gear Research Institute (GRI). Annual corporate membership to the Institute would be $600 and the collected membership fees would be utilized solely for the purpose of supporting Engineering undergraduates (juniors and seniors) at Penn State to work in the laboratories. The laboratories of the Drivetrain Technology Center, which hosts the activities of GRI, is resident to state-of-art gear inspection equipment and a wide range of gear and gear material test machines. Working 40 hours a week during the summer and 10-15 hours a week during the fall and spring semesters would expose these students to a wide range of gear related technologies that they would not encounter anywhere else.

The Board members, most of whom are from the gear industry, were of the opinion that this exposure to gear technology for graduating engineers would be of benefit to the industry, if they were to employ these individuals. On enquiry, such candidates would be available to corporate members for hiring considerations. Matching grants to increase the available funds are also being sought to maximize this opportunity.

This research experience for undergraduates would cost approximately $15,000 per student, all in wages. It is hoped that sufficient funds can be raised to employ at least two students for the summer of 2010. So please consider corporate membership in GRI and help us help you. If your company is interested in interviewing and sponsoring a student directly, we would also be happy discuss this option with you.

Suren Rao
Managing Director

Research Projects

While it is the intent of any designer to design a system that can handle anything that mother nature can throw at it, it is impossible in the natural world to meet this objective. This is especially true of equipment that is required to have a useful life of several decades.

An we have used for clients is to characterize the behavior of the system and its components after it has been subjected to an unusual event and determine how it could be designed to perform for a “safe” period after such an event. In light of this perspective we characterize gear steel fatigue behavior after being subjected to an overload.

Of primary concern has been bending fatigue characteristics of gear teeth subjected to an overload, since bending fatigue tooth failure is by its nature a catastrophic event. Three different kinds of overloads are considered. They are:

1. Impact overload
2. Static overload, and
3. Dynamic overload.

In an impact overload characterization the gear tooth is subject to a controlled impact so as to induce a small amount of plastic deformation of the gear tooth but no other damage. The static overload characterization is also similar except that a static load is applied as opposed to an impact. In the case of a dynamic overload a cyclic overload, determined from the S-N (stress-cycles) curve of the original material, is applied in the range of 100 to 1000 cycles. The impact overload is carefully introduced into the test gear tooth in our drop-weight test stand, described in the previous newsletter (Transmissions 4, 2009). The static and dynamic overloads can be introduced into the test gear teeth on the several single tooth test stands that are available at GRI. Once the overload is applied a full S-N characterization follows, consisting of several bending fatigue tests at different stress levels.

The Gear Research Institute is well equipped to handle all aspects of this type of a research program. While the data obtained in these experiments are proprietary to the sponsors of this effort interesting results have been obtained. This effort continues to better understand gear failures in machinery.

While it appears that the US economy averted a catastrophe, business conditions continue to be lethargic, at best. We, at GRI, are still busy and hope 2010 will bring a revival of the gear industry and impact us in a positive manner. We hope 2010 sees your business return as well.

The Gear Research Institute is a non profit corporation. It has contracted with the Applied Research Laboratory of The Pennsylvania State University to conduct its activities, as a sponsor within the Drivetrain Technology Center. The Gear Research Institute is equipped with extensive research capabilities. These include rolling contact fatigue (RCF) testers for low- and high-temperature roller testing, power circulating (PC) gear testers for parallel axis gears with a 4-inch center distance (testers can be modified to accommodate other center distances), single tooth fatigue (STF) testers for spur and helical gears, gear tooth impact tester, and worm gear testers with 1.75 and 4-inch center distances. Extensive metallurgical characterization facilities are also available at Penn State in support of the Gear Research Institute. For further details on our testing capabilities please go to the Drivetrain Technology Center website or call Dr. Suren Rao, Managing Director, at (814) 865-3537.