Aircraft Wheel-Tire Dynamic Interface Pressure

ABSTRACT: A new sensor for the measurement of ground reaction forces that terminate into the aircraft wheel-tire interface is proposed. Current measurement methods are limited to capturing normal force values. We propose the use of a thin-film sensor based on Innovative Scientific Solutions Inc."s Surface Stress Sensitive Film (S3F). This technology has been used to measure pressure and shear forces at the ground-aircraft tire interface with loads over 40,000 pounds. Current S3F measurement approaches utilize optical imaging of the film, but optical access is not an option for this application. The key innovation is the construction of an S3F sensor that employs a conventional capacitance-based scheme for detection of the normal and tangential film deformations. The film reaction is then modeled using Finite Element Analysis to reconstruct the forces at the wheel-tire interface. The application of these electronics to the S3F will be performed by Applied Nanotech, Inc. who have demonstrated this process for printed circuit boards, flexible electronics and displays, communications instrumentation, and RFIDs. Phase I will include construction of thin-film sensor candidates, validation in bench-top experiments and hydraulic presses, demonstration in an automotive wheel-tire interface, and development of a Phase II design for aircraft wheel-tire testing. BENEFIT: ISSI has an active commercial program, currently led by our sales of Pressure and Temperature Sensitive Paints (PSP/TSP), as well as the illumination components, imaging components, control software, and analysis software to support their usage in aerodynamics research. ISSI is the key commercial source of PSP/TSP technology worldwide, with customers in the US, Japan, Korea, Singapore, China, and several countries in the EU. Total sales from this technology are over $1,000,000 per year with significant growth seen in each of the last 4 years. A new commercial emphasis, in fluid flow, is the use of our Surface Stress Sensitive Films (S3F) for skin friction measurements. Of particular interest are non-optical point sensors which are the focus of this program. These sensors are of value for aerodynamic, hydrodynamic, and biomedical applications. In addition to expanding our commercial presence in aerodynamics and hydrodynamics, ISSI is making a significant push into contact force measurement using technologies such as our patented S3F. This proposal is one example. ISSI is specifically teaming with Bertec Corp. and the University of Akron to develop a system for measurements of shear stress on the feet of diabetics for medical research, clinical diagnosis, and ulcer prevention. Market analysis of this optically-based sensor suggested potential sales of over 200 systems per year with an associated revenue stream of more than $7M, annually. A non-optical S3F sensor that could be molded into a shoe insert, for example, would be of great value in this area, as well as in biomechanics, orthopedics, podiatry and sports medicine. Admittedly, the tire testing market is not likely to be numerically as large as the ones described above. The AUTOPEDIA, website lists over 40 automobile tire manufacturers worldwide. This number increases to over 60 if country-specific divisions are included for the major manufacturers. Many of the major manufacturers produce truck, heavy equipment and aircraft tires as well, but there are some additional firms that focus on specific markets such as heavy or other off-road, equipment. Because of the different sizes, loads, and performance demands of automobile, truck, heavy equipment, and aircraft tires, multiple system sales are possible to a single firm.