Method and apparatus for measuring the strain developed in a coated surface

US5199305A · kind A · utility

Assignee

• The United States of America as represented by the Administrator of the National Aeronautics and Space Administration · US

Inventors

• Sheldon Smith · Rua Antonieta Borges, US
• Clement Hiel · Rancho Palos Verdes, US

Key dates

• Filing date: Oct 21, 1991
• Grant date: Apr 6, 1993
• Expiry date: Oct 21, 2011

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N2203/0682
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A method and apparatus are provided for determining the strain developed in a coated surface. A beam with a coating on a surface thereof is mounted as a cantilever and a force is applied to the free end of the beam to cause deflection of the beam until the coating on the beam fails. The strain in the beam, and hence in the coating at the point of failure, is determined based on the dimensions of the beam, the point along the beam where failure of the coating occurs and the amount of deflection of the beam, and this determination is made independently of the temperature of the beam and the material from which the beam is made. The determination is made based on the equation E=1.5.sub.x /1.sup.3, where E is strain, h is the beam thickness, d is the beam deflection, x is the distance from the free end of the beam to the point where failure of the coating occurred, and l is the length of the beam.