A Brief Review of Some Local Approaches for the Failure Assessment of Brittle and Quasi-Brittle Materials

Brittle failure of components weakened by cracks and notches is a topic of active and continuous research. It is a key topic for all researchers who face the problem of fracture of materials under different loading conditions and deals with a large number of applications in different engineering fields. This topic is significant in all the cases where intrinsic defects of materials or geometrical discontinuities give rise to localized stress concentration which, in brittle materials, may generate a crack leading to catastrophic failure or to a shortening of the assessed structural life. Whereas cracks are viewed as unpleasant entities in most engineering materials, U- and V-notches of different acuities are sometimes deliberately introduced in design and manufacturing of structural components. The main aim of the present contribution is to present a short review of some local approaches applicable near stress raisers both sharp and blunt allowing the reader to have an update state of the art for the considered criteria

Crack initiation at V-notch tip subjected to in-plane mixed mode loading: An application of the fictitious notch rounding concept

The fictitious notch rounding concept is applied for the first time to V-notches with root hole subjected to in-plane mixed mode loading. Out-of-bisector crack propagation is taken into account. The fictitious notch radius is determined as a function of the real notch radius the microstructural support length and the notch opening angle. Due to the complexity of the problem, a method based on the simple normal stress failure criterion has been used. It is combined with the maximum tangential stress criterion to determine the crack propagation angle. An analytical method based on Neuber's procedure has been developed. The method provides the values of the microstructural support factor as a function of the mode ratio and the notch opening angle. The support factor is considered to be independent of the microstructural support length. Finally, for comparison, the support factor is determined on a purely numerical basis by iterative analysis of FE models

Taming the runabout imagination ticket

The ‘puzzle of imaginative use’ (Kind and Kung in Knowledge through imagination, Oxford University Press, Oxford, 2016) asks: given that imagination is arbitrary escape from reality, how can it have any epistemic value? In particular, imagination seems to be logically anarchic, like a runabout inference ticket: one who imagines A may also imagine whatever B pops to one’s mind by free mental association. This paper argues that at least a certain kind of imaginative exercise—reality-oriented mental simulation—is not logically anarchic. Showing this is part of the task of solving the puzzle. Six plausible features of imagination, so understood, are listed. Then a formal semantics is provided, whose patterns of logical validity and invalidity model the six features