Apparatus for testing of elastic materials

Claim 1

APPARATUS FOR THE TESTING OF ELASTIC MATERIALS FOR INTERNAL FLAWS COMPRISING THE COMBINATION OF A PIEZOELECTRIC TRANSDUCER OF BARIUM TITANATE, MEANS FOR APPLYING THE TRANSDUCER TO A SPECIMEN UNDER CONTROLLED PRESSURE CONDITIONS ENABLING ULTRASONIC VIBRATIONS TO PASS IN BOTH DIRECTIONS BETWEEN THE TRANSDUCER AND THE SPECIMEN, A BRIDGE CIRCUIT IN ONE ARM OF WHICH THE TRANSDUCER IN CONNECTED AND IN THE OPPOSITE ARM OF WHICH IS INCLUDED A NETWORK OF ELEMENTS WHICH SUBSTANTIALLY BALANCE THE TRANSDUCER, SAID NETWORK COMPRISING AT LEAST A FIRST VARIABLE CAPACITANCE SIMULATING THE ELECTROSTATIC CAPACITANCE OF THE TRANSDUCER AND A SERIES COMBINATION SHUNTING SAID FIRST CAPACITANCE, SAID COMBINATION INCLUDING AT LEAST A CAPACITANCE AND AN INDUCTANCE SIMULATING THE MECHANICAL CAPACITANCE AND AN INDUCTANCE OF THE TRANSDUCER AND A VARIABLE RESISTANCE SIMULATING THE MECHANICAL LOAD OF THE SPECIMEN, AN AMPLIFIER AND INDICATING SYSTEM IN ONE DIAGONAL OF THE BRIDGE CIRCUIT, AND MEANS FOR SUPPLYING THE OTHER DIAGONAL OF THE BRIDGE CIRCUIT WITH PULSES OF ALTERNATING CURRENT ENERGY OF AN ULTRASONIC FREQUENCY APPROPRIATE TO THE TRANSDUCER.