A finite element model able to reproduce measurement’s errors related to the use of inflation cuff of improper size was made by the ANSYS code. For the analysis it was assumed a simplified geometry which provides a tissue with circular section, placed evenly around the bone and containing the brachial artery and basilic vein, arranged along the same diameter. The dimensions were chosen in reference to those listed by Eycleshymer and Schoemaker: the outer diameter of the bone is 28 mm long, the outer diameter of the muscle tissue is 108 mm, the inner diameter of the artery is equal to 4 mm, the thickness is of 0.6 mm, while the inner diameter of the vein is equal to 7 mm, with the assumption of zero thickness. The air gap was set at 2 mm for an overall width between 40 and 170 mm. The muscle tissue was modeled to form a smooth, elastic and isotropic set composed of skin, muscle, nerves and fat, which was assigned a Young's modulus E = 47.5 kPa. The Poisson's modulus was derived during the model validation and was equal to = 0.04, which might presuppose a behavior of the system similar to a compressible tissue. This value differs by an order of magnitude from those reported in the literature, however, seems quite acceptable in view of the realistic hypothesis, of the complete emptying of vessels during the inflation. The bone was modeled as a not deformable body, anchored to its pilot node placed at the center of the longitudinal axis. The model was validated by testing the measurement errors related to the phenomenon of miscuffing with reference to the corrections proposed by Reid and Chantler.
UN NUOVO MODELLO FEM PER LA VERIFICA DEGLI ERRORI DI MISURAZIONE DELLA PRESSIONE ARTERIOSA
USAI, MARIANGELA;VALLASCAS, RINALDO
2011-01-01
Abstract
A finite element model able to reproduce measurement’s errors related to the use of inflation cuff of improper size was made by the ANSYS code. For the analysis it was assumed a simplified geometry which provides a tissue with circular section, placed evenly around the bone and containing the brachial artery and basilic vein, arranged along the same diameter. The dimensions were chosen in reference to those listed by Eycleshymer and Schoemaker: the outer diameter of the bone is 28 mm long, the outer diameter of the muscle tissue is 108 mm, the inner diameter of the artery is equal to 4 mm, the thickness is of 0.6 mm, while the inner diameter of the vein is equal to 7 mm, with the assumption of zero thickness. The air gap was set at 2 mm for an overall width between 40 and 170 mm. The muscle tissue was modeled to form a smooth, elastic and isotropic set composed of skin, muscle, nerves and fat, which was assigned a Young's modulus E = 47.5 kPa. The Poisson's modulus was derived during the model validation and was equal to = 0.04, which might presuppose a behavior of the system similar to a compressible tissue. This value differs by an order of magnitude from those reported in the literature, however, seems quite acceptable in view of the realistic hypothesis, of the complete emptying of vessels during the inflation. The bone was modeled as a not deformable body, anchored to its pilot node placed at the center of the longitudinal axis. The model was validated by testing the measurement errors related to the phenomenon of miscuffing with reference to the corrections proposed by Reid and Chantler.
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