Freight rail is often the preferred method for transportation of dangerous goods. One particular application is the use of rail to convey radioactive material in purpose built packages. During transit, packages are secured to a rail wagon bed with a tie down system. The design of tie down systems vary considerably depending on package type and rail vehicle, for example shackles, turnbuckles, tie-rods, gravity wells or transport frames are all commonly used. There are also a large number of different packages in existence that all vary in size and mass; typically 1 -7 m in length and 100 kg -100 tonnes in mass. Despite the uniqueness of many transport configurations the design of tie down systems is always carried out using a limited set of design load cases as defined in the appropriate Codes of Practice and Standards. Many authors have suggested that the load cases within the standards need revision or question which load cases should apply to which scenario. In a previous experiment accelerations and strains have been measured on a freight wagon and transport frame of a heavy package during a routine rail journey. From these data new insight into the magnitude and nature of loading has been gained. There is now, at least, limited supporting evidence of real world loading. In the present study the measured accelerations have been used as input to a Finite Element Model (FEM) of the transport frame and a method based on correlation between predicted and measured strains has been developed to determine an appropriate low pass filter cutoff frequency, f c , which separates quasi-static loading from raw dynamic data. The residual dynamic measurements have been assessed using signals processing techniques to understand their significance. The FEM has also been used to assess the presence of contact and boundary nonlinearities and how they affect the agreement between measured and predicted strains.
The response of a thermosetting cross-linked polyethylene, commercially referred to as Vitrite, has been studied experimentally and numerically. Two different testing programmes have been carried out; the first to characterise the mechanical properties of the material, and the second to provide information to validate a finite element model. Strain-rate dependent stress–strain curves have been obtained to determine the static and dynamic mechanical properties of Vitrite in tension and compression. Guided drop testing of a mass onto small scale samples has been used to study their deformation and rebound response. This has been compared to the deformation results of a finite element analysis model of the drop tests using the data obtained from the material characterisation tests as input to the model.
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