Abstract
We had conducted medium scale field indentation tests of JOIA projects, and have reported the pattern of local pressure distribution by the use of pressure data of Tactile sensor (Takeuchi, et. al., 2004). There are high pressure zones mainly inside line-like contact zone at the interface between icesheet and structure in the brittle condition, and these are forming and fading rapidly with a certain size and pressure. It is very interesting to investigate the characteristics of high pressure zone, since force of high pressure zone plays an important role on global force and it relates to non-simultaneous stress transmission to structure in the brittle condition. Mechanism of high pressure zone has been reported by Jordaan (2001, 2008) and Dempsey et al. (2001) have treated the estimation of its pressure theoretically. In the paper, "labeling process" of the image processing was newly applied to tactile sensor data, and the process allows us to find a zone that has adjacent grid pressures. Area, pressure and location of high pressure zone were estimated at each frame of Tactile sensor data through threshold which was taken as a uni-axial compressive strength here.
In the paper, area and force of each zone were calculated and they have a linear relation. Acting position, of x- and y- direction calculated from moment and force of each zone, and distance, between adjacent acting positions, were estimated. Statistics on area, force, acting position and distance of each high pressure zone were considered. Especially, the probability density function on area and distance looks like log-normal type. In addition, these findings allow us to conduct Monte Carlo Simulation to evaluate the slope of upper limit of pressure area curve.
