Imperfection-Sensitivity of Integral and Debonded Sandwich Beams Under Compression

The compressive behavior of sandwich columns with relatively thin facing sheets is investigated. Nonlinear analyses are performed on columns with and without delaminations incorporating a variety of imperfections. The characteristic buckling mode of the columns investigated is one of face-sheet wrinkling. With the onset of wrinkling, the column loses much of its stiffness and buckles in the overall mode. As a result, the column is found to be considerably sensitive to both wrinkling mode imperfections and overall bending introduced by the application of small lateral loads. The sense of imperfection plays a significant role in delaminated specimens. If the imperfection tends to keep the delamination open, it results in a more significant reduction of the load carrying capacity. A comparison of the responses of the beams with and without delamination indicates that the presence of the delamination of relatively short length (1/15 of span) can reduce the maximum load carrying capacity by about 30%.