Comparison Of The Strength To Weight Ratio Of Variable Section Beams With Prismatic Beams

An experiment for examination of the stress distribution in a prismatic cantilever beam and a tapered cantilever beam of equal weight is proposed for national adoption. Strain gauges attached at four identical locations of the two beams will provide data regarding the state of stress for comparison purposes. Obtaining meaningful strain levels, and at the same time avoiding damage due to permanent set of the precious gauged specimens is always a challenge. To control this catch 22 situation, a backward analysis has been conducted to prescribe the allowable range of loads. The students must develop the mathematical model for predicting the levels of strain and stress in the two beams and manually calculate the expected levels of strain and stress. Modeling of the two different beams in ANSYS and comparison of the behavior of the beams may be added as an optional integral part of the project. This experiment vividly illustrates the advantages of the tapered beams over the prismatic ones. Students however, must comment on the extra manufacturing cost of the tapered beams in justification of their final design decisions in different applications.