Development of the Brinell Sandwich Passive Soil Stress Gage.

摘要

The interior of the Brinell Sandwich soil stress gage consists of a layer of small hardened steel balls between softer materials. Indentations in the softer materials (their diameters are measured by a microscope) indicate the maximum compressive force that has been exerted at the location of each ball. A flat, disk-shaped gage body package seals off the space around the balls from external pressure and provides protection against shear in the plane of the sandwich. These gages combine high axial stiffness with good resolution over a range of more than a factor of 100. Sensing ranges of two versions tested are 4 MPa to 470 MPa, and 0.67 MPa to 100 MPa. Laboratory investigations have shown that with pulses ranging from static to approximate half-sines with rise times of 0.1 millisecond, gage performance is not influenced by rate effects. (Author)