A study of modelling approaches for rail vehicle collision behaviour

A rigid wall model has been used widely in the numerical simulation of rail vehicle impacts. Finite element impact modelling of rail vehicles is generally based on a half-width and full-length or half-length structure, depending on the symmetry. The structure and components of rail vehicles are normally designed to cope with proof loading to ensure adequate ride performance. In this paper, the authors present a study of a rail vehicle with driving cab focused on improving the modelling approach and exploring the intrinsic structural weaknesses to enhance its crashworthiness. The underpinning research used finite element analysis and compared the behaviour of the rail vehicle in different impact scenarios. It was found that the simulation of a rigid wall impact can mask structural weaknesses; that even a completely symmetrical impact may lead to an asymmetrical result; that downward bending is an intrinsic weakness of conventional rail vehicles and that a rigid part of the vehicle structure, such as the body bolster, may cause uncoordinated deformation and shear fracture between the vehicle sections. These findings have significance for impact simulation, the full-scale testing of rail vehicles and rail vehicle design in general.

Segregation of bulk particulates through multiple process handling steps

Segregation or de-blending of bulk particulates is a problem that is encountered in many industrial sectors. The magnitude of segregation can often determine whether a complete production batch can be transferred for onward processing within the plant or released to market. It is a phenomenon that impacts directly upon the profitability of a process. Segregation can occur through a coincidence of a range of variables that relate to the process and bulk particulate properties, common mechanisms for this include; percolation, surface effect (rolling) and elutriation. The importance to industry of predicting the sensitivity of bulk particulates to segregation cannot be under-estimated, and to this end various test procedures have been developed. Within many industries striving to improve product quality and reduce wastage, the determination of variability in blend consistency caused by segregation is an increasing priority. This paper considers recent work undertaken to evaluate the effects of multiple handling operations on the degree of segregation that results. The bulk properties of segregability (and resulting flowability) can not only influence the product consistency, but can have great influence over the process (production) control and performance.