Further Development of 3-D In-Situ Soil Stress Sensor

A field portable monitoring system is proposed that will provide ARO with the capability to measure the 3-D in-situ state of stress in soils which results from vehicle element's terrain interaction. The system will comprise a compact 3-D stress sensingpackage that is connected via a rugged flexible cable assembly to a field-portable controls/ excitation-and-amplification source and to an integrated data acquisition / Lap Top PC arrangement. The approach to stress measurements will consist in using threesolid- or fluid-coupled high-output thin-film piezoresistive Carbon stress gauges that are orthogonal-mounted on the faces a suitable solid substrate block or behind its faces at the bottom of small fluid cavities. The 3-D sensing package will beintegrally attached to a short rigid stem that extends into a set of armored and flexible output leads. Such arrangement can be made very small ( one cubic centimeter ) or as large as needed to meet the requirements. The Carbon stress gauge is capable ofresolving stresses as low as a few PSI up 15,000 PSI or above in dynamic or static environments. Relying on nearly thirty years of experience in designing and manufacturing numerous types of soil stress sensors for UGT and AGT applications in support tonearly all US DOE and DOD Laboratories, the proposed system will be constructed and fully evaluated, and rendered functional at our test facility under simulated but representative stress environments prior to its delivery to the Army. Coupling to soil andmethods for minimizing ground disturbance will also be investigated. A very degree of success is anticipated from this effort. BENEFITS: To allow researchers to model vehicle element interaction with soils. Earth Quake measurements and mining industryapplications.