Events Calendar

Aerospace and Mechanical Engineering Seminar Series

Speaker: Emmanuel Gdoutos, Professor in Department of Civil and Environmental Engineering at Northwestern University, Evanston, IL & School of Engineering, Democritus University of Thrace, Xanthi, Greece

Talk Title: Failure Modes of Sandwich and Cellular Materials

Series: Aerospace and Mechanical Engineering Seminar Series

Abstract: Sandwich structures consisting of strong and stiff facings and light weight cores offer improved stiffness and strength to weight ratios compared to monolithic materials. Under flexural loading the facings carry almost all of the bending, while the core takes the shear loading and helps to stabilize the facings. Facing materials include metals and fiber reinforced composites. The latter are being used in advanced applications due to the large strength-to-weight ratio. The core materials mainly include honeycombs, cellular foams and wood. In the present seminar the failure behavior of composite sandwich beams subjected to three- and four-point bending will be presented. The beams were made of unidirectional carbon/epoxy facings and various core materials including PVC closed-cell foams, a polyurethane foam and an aluminum honeycomb. Various failure modes including facing wrinkling, indentation failure and core failure were observed and compared with analytical predictions. It was established that the initiation, propagation and interaction of failure modes depend on the type of loading, constituent material properties and geometrical dimensions. The crack growth behavior of polymeric foams under mixed-mode loading conditions will also be presented. Polymeric foams are anisotropic materials and crack kinking occurs even though the applied load is perpendicular to the crack plane. The stress analysis of the plate was performed by finite elements. Crack trajectories for various angles of the orientation of the axes of orthotropy of the material with respect to the applied load were obtained.

Biography: Emmanuel Gdoutos is Professor of Theoretical and Applied Mechanics and Director of the Laboratory of Applied Mechanics at the Democritus University of Thrace, Greece, and Adjunct Professor at Northwestern University. His interests and experience include many areas of mechanics of materials with emphasis on experimental mechanics, fracture mechanics, composite materials and nanotechnology. He serves on the editorial board of eight international journals. He has awarded two Fulbright fellowships and an excellent teaching award from the University of Toledo. He has held numerous lectureships and visiting professorships (Lehigh Univ., Univ. of California at Santa Barbara and Davis, Toledo Univ., Michigan Technological University. and Northwestern University). He served as chairman of the Department of Civil Engineering of the Democritus University of Thrace. He authored over 240 papers in refereed journals and conference proceedings, 15 books and edited 14 books. His book titled "Fracture Mechanics - An Introduction" is a widely used textbook for fracture mechanics courses.

Host: Professor Paul Ronney

Location: Seaver Science Library (SSL) - 150

Audiences: Everyone Is Invited

Contact: Valerie Childress