Blog posts

Stress analysis of composite cylindrical shells with an elliptical cutout  

Erkan Oterkus & Erdogan Madenci & Michael P. Nemeth

This paper presents an anharmonic lattice statics analysis of 180 and 90 domain walls in tetragonal ferroelectric perovskites. We present all the calculations and numerical examples for the technologically important ferroelectric material PbTiO3. We use shell potentials that are fitted to quantum mechanics calculations. Our formulation places no restrictions on the range of the interactions. This formulation of lattice statics is inhomogeneous and accounts for the variation of the force constants near defects.

The simple extension tear test-piece also referred to as the trousers sample is widely used to study crack propagation in rubber. The corresponding energy release rate, called tearing energy for rubber materials, was first established by Rivlin and Thomas (Rupture of rubber. I. Characteristic energy for tearing. J. Polym. Sci., 10:291–318, 1953); a second derivation was proposed later by Eshelby (The calculation of energy release rates. In G. C. Sih, H. C. van Elst, and D. Broek, editors, Prospects of Fracture Mechanics, 69–84, Leyden, Noordhoff, 1975).

All metallic, hollow sandwich cylinders having ultralight two-dimensional prismatic cores are optimally designed for maximum thermo-mechanical performance at minimum mass. The heated cylinder is subjected to uniform internal pressure and actively cooled by forced air convection. The use of two different core topologies is exploited: square- and triangular-celled cores. The minimum mass design model is so defined that three failure modes are prevented: facesheet yielding, core member yielding, and core member buckling.

In response to a NSF call for proposal on Cyberinfrastructure Training, Education, Advancement, and Mentoring for Our 21st Century Workforce (CI-TEAM), in June 2006, several of us submitted a proposal entitled "iMechanica:  Leveraging Cyberinfrastructure to Evolve All Knowledge of Applied Mechanics"