Gordana Vasic Franklin and Oliver Warlow
Gordana Vasic Franklin: "Wear and Crack Initiation in Rails"
During operation rails wear and crack. This is a major safety problem that can lead to derailment and casualties, which may be devastating in terms of loss of life, but also costs millions. The picture in the UK is not so grim, with a declining trend, but derailments are still a major cause for concern around the world.
Rails have to be maintained regularly to provide good dynamic stability – to keep freight trains from derailing and for passenger comfort on high speed trains. Grinding tracks typically removes only about 0.1 mm of material from the railhead, which shows just how sensitive train dynamics is to the shape of the wheels and rails; 0.1 mm near the rail surface is also the most highly stressed and deformed material in the rail, and is the place where cracks initiate.
The overall aim of this work is to gain further knowledge of new rail grade materials’ behaviour under cyclic loading, in order to help improve rail material characteristics in future productions, to help with the selection of rail material for certain types of rail operation and optimise maintenance through adjusting maintenance schedules and grinding depths to realistic figures dependant on real material deterioration, and to develop new rail renewal strategies.
The main aim is to make rails safer.
Oliver Warlow: "Kinematic and Anatomical Measurement for Biomechanical Finger Models"
Biomechanical models of the fingers are used to gain a greater understanding of their internal loading which will help guide clinicians treat injuries and pathologies. These models require accurate measurement of body kinematics, external reaction forces and anthropometry. The aim of this work was to gain a greater understanding of the predicted internal loading using biomechanical finger models and propose improvements in the kinematic and anatomical measurements required as their inputs.
Through sensitivity analysis, correlations between uncertainty in the anthropometry and kinematics with predicted internal loading were found. This showed that the predicted internal loading was most sensitive to changes in the moment arm of the flexor digitorum profundus tendon.
A new method of motion capture of the fingers using functionally defined joint centres was assessed. This method required the subject to complete a set of calibration movements. Subjects with an injury or pathology may have significantly reduced mobility, therefore an analysis was carried out to quantify the effect of reducing the available movement to that of a subject with pathological mobility. This resulted in errors of less than 5% in the predicted internal loading. It was important to note however, that in the extreme cases of deformity and lack of mobility these functional techniques would not be suitable.
Finally, a combined method of ultrasound and stereo-photogrammetry to measure the in-vivo moment arm of the flexor digitorum profundus was developed, enabling non-invasive subject specific measurements. Measurement made using this technique found moment arms within the range of previous studies but they were found to alter the predicted internal loading by up to 84%. This demonstrated the importance of subject specific measurement. Although this was only a pilot study with a single subject it showed how this technique could be applied not just to the fingers but to other parts of the body where subject specific measurements of moments arms are important.
Published: 9th January 2012