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Wheelchair seating systems are specialised for a number of reasons as users can have impaired mobility, which increases the possibility of pressure build up. These areas of high pressure frequently occur in the trunk region under the bony prominences known as the Ischial Tuberosities (IT), pressure ulcers may occur consequently. Polyurethane foam has been in use for some time in wheelchair seating systems as it exhibits good pressure relieving capabilities in most cases. However, little quantitative research has gone into foamed polymers, in comparison with conventional elastomeric materials. This lack of knowledge can ultimately lead to more time being spent in fitting, increased possibility of refitting and potentially an increase in trunk region pressures leading to the development of ulcers. Test results were used to accurately validate a Visco-Hyperfoam material model. Accurately simulating an indentation procedure using FE software verified the validation of the material model.
Briody, C., Duignan, B., Jerrams, S.: Testing, modelling and validation of numerical model capable of predicting stress fields throughout polyurethane foam. Proceedings of the 7th European Conference on Constitutive models for Rubber (ECCMR). Dublin, Ireland, 20 - 23 September, 2011.