Accession Number : AD0438826


Title :   DEVELOPMENT OF A SOIL STRAIN GAGE FOR LABORATORY DYNAMIC TESTS.


Descriptive Note : Final rept., 1 Mar-31 Dec 63,


Corporate Author : IIT RESEARCH INST CHICAGO ILL


Personal Author(s) : Keller,Robert W ; Anderson,Marvin E


Report Date : Apr 1964


Pagination or Media Count : 43


Abstract : A 'four-coil' soil strain gage was developed for measurements in laboratory samples subjected to static or dynamic loads. This report covers work done under a program for continued gage development and modifications which have resulted in the 'coil-plate' gage. The coil-plate gage can be used for applications for which the fourcoil gage in its present form is not suitable. The new coil-plate gage can be operated with the same auxiliary electronics used with the fourcoil gage. The gage consists of two bifilarly wound coils and two conducting plates and associated electronic instrumentation. On bifilar coil and plate is embedded in soil as the strain sensing element; the other coil and plate is externally positioned on an adjustable precision mount to serve as a reference. The principle of operation is that of a series adding transformer having its secondary connected to an open circuit-null balancing system to permit accurate measurements of small strains. Measurements can be made close to boundaries and to materials exihibiting magnetic properties. (Author)


Descriptors :   STRAIN GAGES , SOILS , COILS , STRAIN(MECHANICS) , INSTRUMENTATION , TRANSFORMERS , MEASUREMENT , SOIL MECHANICS , ENGINEERING DRAWINGS , TRANSISTORS , ELECTRIC BRIDGES , POWER SUPPLIES , ELECTRODES


Distribution Statement : APPROVED FOR PUBLIC RELEASE