Numerical Simulation And Experimental Verification On Animal Thorax Model Under Physiological Load

Pectus excavatum is a congenital and associated with familial thoracic deformity disease,accounting for 90% of all chest wall deformity. It makes the sternum and costal cartilage inward depression, the cause for patients with cardiopulmonary oppression. Meanwhile, the appearance of the funnel deformity, seriously affects the patient’s mental health, make patient introverted and have sense of inferiority.At present, the main treatment of pectus excavatum orthopedic operation is minimally invasive operation represented by Nuss. The method of Nuss is lifting depressive sternum and costal cartilage in keeping with thoracic bones complete, but which involved the changing rule of the lifting force and changes in the environment after thoracic large deformation mechanics of biomechanics research seldom. In the study of numerical calculation, different scholars use different calculation model and different calculation method, the result of numerical calculation is still lack of the experimental verification. Limited by ethics, it’s can’t adopt the method of electrical measurement experiment of strain measurement in the human body directly, to verify the accuracy of calculating model and method of using the numerical simulation through the comparison of strain and displacement.At present, we can use model of artificial bone thoracic and animal thoracic model in the experimental study, considering the need to study the effect of thoracic intercostal muscle deformation, this paper adopted electric measurement test method to study the sheep thoracic model’s thoracic displacement and strain distribution of rib and costal cartilage under physiological load. With fresh animal(sheep) thorax as the research object, to retain the intercostal muscles and sternal inside muscle, the rib on the upper and lower ends and the rib cartilage are adhered with 3 groups of resistance strain gauge, measuring point layout reference the body funnel chest orthopedic process the results of numerical calculation.Through the WDW-10 material testing machine to exert sagittal thoracic displacement, which reference the orthopedic displacement of funnel chest, get the load-displacement curve, and through dynamic resistance strain instrument to obtain measuring points’ strain. The author also studied the effect of intercostal muscles for animal thoracic deformity, remove the intercostal muscles of the thoracic applied sagittal plane displacement on material testing machine, numerical reference without removing the intercostal muscles thoracic model displacement, got the without intercostal muscles thoracic load-displacement curve and the strain. By comparing the displacement-load curve and strain numbers of whether have intercostal muscles of the thorax, to determine the effect of deformation in the model under physiological load regularity.The paper also underwent CT scanning for animal thorax, and rebuilt the animal thoracic3 D solid model of the sternum, vertebral and rib. Three-point bending test on rib, and makingthe thoracic specimen carried out compression test, we could obtained material parameters of rib and thorax. Referring to animal experiments measuring the the thorax, the model was applied to the corresponding displacement loads and constraints, to calculate displacement and distribution of stress and strain of the animal thorax model.Finally, the numerical simulation of the thorax to get the animal with experimental results were compared and analyzed to study the main factors error of numerical simulation and experimental results.The paper guide for pectus excavatum orthopedic result of numerical simulation using reasonable calculation model and calculation methods, as well as to further develop the model of thoracic electrical test experience have good reference value, including animal thorax model and artificial thorax model.