A closed-form solution for predicting the tangential stress of an inclusion locatedin mixed mode I and II crack tip field was developed based on the Eshelby equivalent inclusiontheory. Then a mixed mode fracture criterion, including the fracture direction and the criticalload, was established based on the maximum tangential stress in the inclusion for brittle inclusion-induced fracture materials. The proposed fracture criterion is a function of the inclusion fracturestress, its size and volume fraction, as well as the elastic constants of the inclusion and the matrixmaterial. The present criterion will reduce to the conventional one as the inclusion having thesame elastic behavior as the matrix material. The proposed solutions are in good agreement withdetailed finite element analysis and measurement.
Flexible, large area electronics using various organic and inorganic materials are beginning to show great promise. During manufacture and service, large deforma- tion of these hybrid materials will pose significant challenges in terms of high performance and reliability. A deep understanding of the ductility or flexibility of macroelectronics becomes one of the major issues that must be addressed ur- gently. This paper describes the current level of understanding on the thin-film ductility, both free-standing and substrate-supported, and relevant influencing factors.
200-nm-thick Au interconnects on a quartz substrate were tested in-situ inside a dual-beam microscope by applying direct current,alternating current and alternating current with a small direct current component. The failure behavior of the Au interconnects under three kinds of electric currents were characterized in-situ by scanning electron microscopy.It is found that the formation of voids and subsequent growth perpendicular to the interconnect direction is the fatal failure mode for all the Au interconnects under three kinds of electric currents.The failure mechanism of the ultrathin metal lines induced by the electric currents was analyzed.
The microstructures of the Saxidomus purpuratus shell were observed.It was found that the inner and middle layers of the shell are composed of crossed lamellae,while the outer layer exhibits porous structures.With the characteristic structure of each layer,the hardness of inner layer with narrow domains in crossed lamellar structure is the highest,and that of middle layer with wide domains is lower,while the outer layer has the lowest hardness.The damage morphologies of the indentations change a lot,depending not only upon the magnitude of the indentation load,but also upon the orientation between the indentation direction and the crossed lamellae in the microstructure of the shell,which illustrates the anisotropy in mechanical properties of such shells.
