Recording the Initiation and Development of Failure in Timber

Abstract

MICROSCOPIC examinations of fractures in materials have been restricted, in the past, to the detailed study of surfaces after failure has occurred; pre-failure development within the material has remained an elusive phenomenon. Thus the changes in structure which occur during stressing have usually been deduced from information obtained from a series of blocks each being subjected to different degrees of stress. While this approach can yield valuable information on the sequential changes in the internal structure of a material before failure, it lacks continuity, because it introduces both variations between samples and a degree of subjectivity in the interpretation of the sequence from the observed stages.