Dynamic Aircraft Tire Footprint Sensor (DATFS)

The ability to visualize and quantify the slip velocities of the tire contact patch during touchdown, high-speed braking, and takeoff of aerospace vehicles could provide insight into tire life and braking performance. The ability to capture and characterize contact stresses at the tire-runway interface should lead to improved tire life and braking performance. We propose a new measurement system using Surface Stress Sensitive Film to resolve continuous measurement of normal and tangential contact stress at the tire-runway interface in the LGTF 168i facility. The basis of this measurement is an elastic film that deforms under the action of applied loads. The reaction of the film is monitored by imaging the surface and detecting the tangential and normal deformation of the film. The film reaction is modeled using a finite element analysis model. The result is a continuous distribution of skin friction and pressure over the filmed surface. The film has been calibrated at a range of temperatures from 160 to 470 K. Experimental measurements have been demonstrated under aircraft tires at loads over 60,000 pounds. The quantitative accuracy of the pressure and skin friction measurements have been demonstrated to be better than 5% full scale in a variety of experiments.