Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2005.Includes bibliographical references (leaf 30).An experimental study was conducted to investigate the possible influence of shear lag in the discrepancy between the theoretical and measured stiffness of truss core sandwich beams. In previous studies, the measured values of stiffness in loading have proven to be 50% of the theoretical stiffness during three point bending tests. To test the effect of shear lag on this phenomenon, the beams' dimensions were altered to decrease the presence of shear lag in a gradual manner so a trend could be observed. The experimental trails were carried out on three types of beams each with different diameters of truss material. Results show that this study has improved the accuracy of the measured results from previous studies with the two smallest truss diameter beams. Because the discrepancy between the theoretical and measured values is the greatest for the largest beams, (when the shear deflection has the least influence), it is concluded that shear lag is not responsible for the discrepancy between measured and theoretical stiffness.by Ryan Roberts.S.B
