Notice of RetractionShear response of a clamped beam subjected to intense dynamic loading with considering weakening effect of the shear sliding cross-section
The present paper, adopting a rigid, perfectly plastic idealization material model and a square yield locus, with the consideration of two conditions of weakening and non-weakening effects of transverse shear sliding section, analyses the shear response of a clamped beam in the initial plastic deformation stage subject to a uniformly distributed impulsive loading and the precondition of possible shear failure mode, writes the shear's movement equation, puts forward the expressions of shear velocity and shear sliding volume, finally the conclusion of the availability of different shear response model for weakening effect is drawn.
Failure of plastic structures under intense dynamic loading: modes, criteria and thresholds
Abstract This paper surveys the failure modes, criteria and thresholds of plastic structural members (beams, rings, plates and thin shells, etc.) subjected to intense dynamic loads, such as impulsive velocities or impact. Besides the three basic failure modes identified by Menkes and Opat [7] for impulsively loaded beams, namely, large inelastic deformation (Mode I), tensile tearing (Mode II) and transverse shear failure at the supports (Mode III), more complicated failure behaviours observed in the cases of complex structural members and/or dynamic loading conditions are summarized and discussed. All the failure criteria used in the relevant theoretical analyses including elementary failure criterion, energy density criterion and quasi-static equivalent energy criterion, etc., are commented upon. The threshold impulsive velocities for the onset of Mode III failure of fully clamped beams predicted from various approaches are compared with each other, as well as with the relevant experimental results. Particular attention is paid to structural members with macro imperfections (for example, containing cracks or notches), where failure which usually originate from the imperfections are fracture-dominant so that local fracture criteria, such as the J-integral criterion, should be incorporated into the global structural failure description. In addition, some most recent results of the authors’ studies are briefly presented.
A Study on Technology Embedded English Classes Using QR Codes
The development of information and technology has brought plenty of changes to the educational environment. The prevalence of smart phones is particularly playing a huge role in shaping learning methods. Smart phones provide the opportunity to scan QR codes, which can greatly ease access to information. Due to a high recognition speed, recognition rate, and restoration rate, they can be useful tools for English teachers to use in their class. In this study, we suggest using QR codes for writing and picture descriptions. Based on this study, more research should invest in Technology Embedded English teaching models to create better English classes for students.