Title: Impact-Echo: The Complete Story

Author(s): Mary Sansalone

Publication: Structural Journal

Volume: 94

Issue: 6

Appears on pages(s): 777-786

Keywords: flaws; impact-echo; nondestructive testing; quality control; research; stress wave propagation.

DOI: 10.14359/9737

Date: 11/1/1997

Abstract:
Impact-echo’s history is an interesting story of how a real need for nonde-structive test methods for flaw detection in concrete structures led to a sys-tematic and sustained basic and applied research effort to develop such a method, beginning in 1983, at the National Bureau of Standards, and con-tinued since 1987 at Cornell University. This paper discusses the contributions of the people and the organizations who carried out the theoretical, numerical, laboratory, and field studies that established the method and who developed the software and instrumentation that gave rise to a patented impact-echo field system. It also documents how this effort was undertaken and sustained with government and industry funding. Subsequently, this paper draws on knowledge gained over twelve years of research to provide, for the first time, a unified explanation of impact-echo theory as it applies to the testing of structural elements, including plates (slabs, walls, bridge decks, pavements, etc.), bars (beams and columns), and hollow cylinders (pipes and tunnel and mine shaft liners) and to the detection of flaws within these elements. The last key pieces fell into place in 1995, and it is now possible to explain in a concise and coherent way the principles upon which impact-echo testing is based.