ANÁLISIS NUMÉRICO DE PRUEBAS EXPERIMENTALES DE EXTRACCIÓN EN UN TORNILLO CORTICAL MINIATURA (NUMERICAL ANALYSIS OF PULL-OUT TESTS IN A MINIATURE CORTICAL SCREW)
Resumen
Las pruebas de extracción son una herramienta que permite comparar la estabilidad de los tornillos médicos. Las pruebas experimentales están limitadas a solo obtener la gráfica fuerza-desplazamiento. El análisis numérico permite complementar las pruebas de extracción para poder identificar las zonas de concentración de esfuerzos y deformaciones.
Se analizó de manera experimental y numérica tornillos corticales miniatura. Se utilizo un tornillo con rosca HA 1.5 y con longitud de 18mm. Los tornillos fueron insertados en espuma de poliuretano con una densidad de 640.74 kg/m^3. Se realizaron 3 pruebas experimentales con el mismo tipo de tornillo y espuma para obtener la curva fuerza-desplazamiento. El análisis numérico se realizó en Ansys mediante una simulación explicita en un entorno 2D, se obtuvo la curva fuerza-desplazamiento y la concentración de los esfuerzos y deformaciones.
La simulación permitió obtener, con un porcentaje de error de 1.74%, la fuerza de extracción en estos tornillos corticales. La grafica esfuerzo-desplazamiento difieren en cuanto a comportamiento, esto se debe a las limitaciones del análisis 2D asimétrico que se realizó.
Palabras clave: Análisis explícito, Elemento finito, Espuma de poliuretano, Prueba de extracción, Tornillo cortical.
Abstract
Pullout testing is a tool that allows you to compare the stability of medical screws. Experimental tests are limited to only obtaining the force-displacement graph. Numerical analysis allows us to complement the extraction tests to identify the areas of concentration of stress and deformations.
Miniature cortical screws were analyzed experimentally and numerically. A screw with an HA 1.5 thread and a length of 18mm was used. The screws were inserted in polyurethane foam with a density of 640.74 Kg/m^3. Three experimental tests were carried out with the same type of screw and foam to obtain the force-displacement curve. The numerical analysis was carried out in Ansys through an explicit simulation in a 2D environment, the force-displacement curve and the concentration of the stresses and deformations were obtained.
The simulation allowed us to obtain, with an error rate of 1.74%, the extraction force in these cortical screws. The stress-displacement graph differs in behavior, this is due to the limitations of the asymmetric 2D analysis that was carried out.
Keywords: Explicit analysis, Finite element, Polyurethane foam, Pull-out test, Cortical screw.
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