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US 4,056,974 AGranted
Method and hydraulic testing apparatus for performing resonance tests
AssigneeCarl Schenck AG
InventorsFriedrich Klinger, Josef Beran, Jan Brezina
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AssigneeCarl Schenck AG
InventorsFriedrich Klinger, Josef Beran, Jan Brezina
Estimating the term…
Materials, or structural components are tested under resonance conditions by means of a pressure operated load mechanism controlled by a servo-hydraulic control unit. The pressure medium is part of the oscillating system. The spring rate or stiffness of the pressure medium is adjusted relative to the spring rate of the test sample, or rather relative to the spring rate of the entire oscillating system in such a manner that the maximum pressure occurring at resonance operation corresponds as close as possible to the rated supply pressure of the system. The load mechanism comprises a single cylinder for producing dynamic loads for the resonance operation and also static loads of substantially the same size as said dynamic loads.
In a method for resonance testing of materials and structural elements in which a test sample constitutes with the members of a testing apparatus a unit including a load mechanism with a single cylinder piston arrangement forming two cylindrical chambers and a pressure medium in said load mechanism, and an oscillatory system driven at resonance, the improvement comprising the steps of incorporating said pressure medium in the load mechanism as an elastic element of said oscillatory system, adjusting the spring rate of the pressure medium relative to the spring rate of the test sample or relative to the spring rate of the entire oscillatory system of the testing apparatus, further adjusting the spring rate of the pressure medium also relative to the mass of said oscillatory system, and supplying the pressure medium to said single cylinder piston arrangement for exciting the oscillation of said oscillatory system, at high pressure in said single cylinder piston arrangement, whereby any pressure difference between supply pressure of the system and the pressure in the single cylinder piston arrangement at the time of pressure supply is minimized.
In a hydraulic testing apparatus for testing test samples at resonance, comprising a hydraulically operated load mechanism including an oscillatory system with a single cylinder piston arrangement having a pressure medium therein for applying to a test sample dynamic loads in a resonance operation as well as pre-loads, and hydraulic control valve means operatively connected to said single cylinder piston arrangement, the improvement comprising a hydraulic control unit operatively connected to said control valve means and responsive to the applied testing forces, said test sample and said pressure medium in said single cylinder piston arrangement each forming an active elastic spring element of said oscillatory system, said hydraulic control unit operating said control valve in such a manner that oscillation exciting pressure is supplied to the oscillatory system at high pressure in said single cylinder piston arrangement.
Dependencies are inferred from the claim text.