ELECTROMAGNETIC GAGE TECHNIQUES FOR DYNAMIC TENSILE FRACTURE

ELECTROMAGNETIC GAGE TECHNIQUES ARE IDEALLY SUITED TO MEASURING THE DYNAMIC TENSILE FRACTURE OF A BROAD VARIETY OFMATERIALS. AS ELECTROMAGNETIC SENSING ELEMENTS CAN BE CONSTRUCTED OF ANY CONDUCTING MATERIAL AND ARE NOT AFFECTED BY MICRO-DEFORMATION THEY CAN BE READILY EMBEDDED IN CERAMICS, PLASTICS, COMPOSITES, CONCRETE, ROCKS AND OTHER NON-CONDUCTING MATERIALS FOR MAKING PRECISE IN-MATERIAL MEASUREMENTS. BECAUSE THE TECHNIQUES ARE BASED UPON FARADAY'S LAW OF INDUCTION, IN-MATERIAL VELOCITIES AND DISPLACEMENTS CAN BE DIRECTLY COMPUTED FROM KNOWN GAGE GEOMETRIES AND MAGNETIC FIELD STRENGTH. WHILE GAGE FUNCTIONING IS QUITE SIMPLE IN THEORY, CONSIDERABLE EFFORT MUST BE DEVOTED TO GAGE EMPLACEMENT TECHNIQUES AND DATA REDUCTION METHODS. IT IS PROPOSED TO DEVELOP AND DEMONSTRATE GAGE PLACEMENT TECHNIQUES AND DIGITAL DATA ACQUISITION, REDUCTION AND INTERPRETATION METHODS SUITABLE FOR MAKING DYNAMIC TENSILE FRACTURE MEASUREMENTS. THE PROPOSED EFFORTS WILL FOCUS UPON DYNAMIC TENSILE FRACTURE INA SPECIALIZED TENSILE HOPKINSON BAR ARRANGEMENT, BUT THE TECHNIQUES SHOULD BE APPLICABLE TO A BROAD RANGE OF DYNAMIC TESTS. THE METHODS WOULD ALSO BE APPLICABLE TO THE STUDY OFUNSTABLE DYNAMIC FRACTURE IN STATICALLY LOADED TESTS.