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.
Prediction of a representative point for rail temperature measurement by considering longitudinal deformation
Monitoring rail temperature is very important for determining the safe running speed of trains and to prevent buckling. In general, the maximum variation of the internal rail temperature can be >7 ℃ depending on the point of measurement. However, there is as yet no sufficient information about how to predict the measurement point to represent the thermal deformation due to temperature distribution. In this study, the authors report a new point, called the representative measurement point, at which the rail temperature can be measured. This point considers the average deformation of the rail through structural analysis by adopting experimental and actual rail temperature data. The authors designed and installed a measurement system similar to an actual rail environment. Using the system, various data were acquired (internal/surface rail temperature and weather data) for 10 months. On the basis of these data, an analysis was done to calculate the average deformation point through thermal analysis. Finally, the representative measurement point was proposed as the position at which the average deformation point converges regardless of weather or seasons. The authors believe that the method described herein is advantageous in that it could be used in a high-accuracy temperature-monitoring system and for predicting thermal deformation and buckling.