6,332 publications from this institution
No abstract is provided for this article.
Take a drinking straw and bend it from its ends. After sufficient bending, the tube buckles forming a kink, where the curvature is localized in a very small area. This instability, known generally as the Brazier effect, is inherent to thin-walled cylindrical shells, which are particularly ubiquitous in living systems, such as rod-shaped bacteria. However, tubular biological structures are often pressurized, and the knowledge of the mechanical response upon bending in this scenario is limited. In this work, we use a computational model to study the mechanical response and the deformations as a result of bending pressurized tubes. In addition, we employ tension-field theory to describe the mechanical behaviour before and after the wrinkling transition. Furthermore, we investigate the development and evolution of wrinkle patterns beyond the instability, showing different wrinkled configurations. We discover the existence of a multi-wavelength mode following the purely sinusoidal wrinkles and anticipating the kinked configuration of the tube.
No abstract is provided for this article.
We found a significant positive association between the Western dietary pattern and the risk of colon cancer.
The durability of thermal barrier coatings for reciprocating internal combustion engine applications was investigated using a coupled, unsteady fracture-based thermomechanics model. The intra-cycle engine heat flux varies substantially in magnitude and has frequency similar to that of the coating thermal timescale, giving rise to relatively large spatial temperature nonuniformity within the coating that varies temporally. A finite difference scheme was used to calculate the temperature field. An analytical model that assumes equi-biaxial stress followed by plane strain delamination was used to evaluate an energy release rate that represents the driving force for cracking. Because the location and time of the peak energy release rate cannot be established a priori, they were computed for all times in the cycle. The peak energy release rate was found to occur later in the cycle than the peak surface temperature, and was often located within the coating as compared to at the coating–substrate interface where there was a mismatch in coefficient of thermal expansion. Coating thickness was found to affect both the magnitude of the peak energy release rate and its location. The residual stress, which arises from the coating deposition process, was found to have a significant effect on the peak energy release rate, and may be a process parameter that can be used to promote coating life. The computational framework demonstrated insight regarding the trade-off between engine thermodynamic performance and coating durability.
Elastic reciprocity and geometric symmetry are used to constrain the expressions for stresses due to introduction of line dislocations near a half-space surface. Specifically, a relationship is shown to exist between the changes induced by dislocations of orthogonal Burgers vectors (normal and parallel to the free surface). These results are used to address inconsistencies of solutions in the literature.
