Four Point Bending: A New Look

Abstract

Four point bending (FPB) is a cornerstone element of the beam flexure portion of a sophomorelevel mechanics of materials course. The FPB lecture has traditionally developed the theory from free body diagram through beam deflection, with related homework problems providing analytical practice. Similarly, the FPB laboratory, which has been essentially unchanged for nearly two decades, has provided students an opportunity to experimentally and analytically verify and validate beam flexure theory. Although excellent correlation between theoretical and experimental results was frequently obtained, hardware requirements have limited the accuracy and amount of data that collected within a standard 110-minute laboratory session.Recent FPB laboratory upgrades utilizing data acquisition (DAQ) hardware and software have enabled the students to test a much larger sample of beams in roughly the same timeframe with increased repeatability. The DAQ upgrade has facilitated increased understanding of flexural theory, introduced modern experimental methods in both lecture and laboratory, given students a more robust data set upon which to base their analyses, and enhanced student experiences with technical report writing. This paper includes an overview of FPB theory, analysis techniques, and traditional laboratory procedures, and details the success of the FPB DAQ upgrade, operation, and outputs.