Recursive hexapod system and method for multiaxial mechanical testing

US8978480B2 · kind B2 · utility

Assignees

• United States of America as represented by the Secretary of the Air Force · US
• The United States of America, as represented by the Secretary of Agriculture · US

Inventors

• John G. Michopoulos · Washington, US
• John Hermanson · Santa Clarita, US
• Athanasios Iliopoulos · Bethesda, US

Key dates

• Filing date: Aug 2, 2012
• Grant date: Mar 17, 2015
• Expiry date: Jul 16, 2033

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N2203/0617
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A recursive hexapod testing machine for mechanical testing of deformable material specimens under six degrees of freedom multiaxial loading. The machine includes a fixed base, a movable base connected to the fixed base at by a hexapod arrangement of six linearly extendable actuator linkages, with an end of each linkages attached to the movable base and the other end of the linkage attached to the fixed base. Each actuator linkage includes a hydraulic cylinder and piston, a digitally-controlled electro-hydraulic servo-valve for actuating the hydraulic cylinder in response to a digital command string, a load cell in line between the piston and the universal joint attached to the movable base, a linear variable displacement transducer for measuring extension of the piston, and a magneto-resistive position transducer for measuring a position of the piston. The servo-valves extend each hydraulic cylinder a predetermined amount to effect a desired motion of the material specimen.