Fitting of Hyperelastic Constitutive Models in Different Sheep Heart Regions Based on Biaxial Mechanical Properties

Ṋemavhola, Fulufhelo; Pandelani, Thanyani; Ngwangwa, Harry

doi:10.1101/2021.10.28.466240

Cited by 3 publications

(1 citation statement)

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“…The mechanical material properties of the sheep trachea were observed to be nonlinear anisotropic and hyperelastic material, similar to other biological soft tissues (Grillo, 1989). Biaxial testing is a reliable method utilised in understanding the mechanical behaviour of soft tissues (Nemavhola, 2017b;Nemavhola et al, 2021b;Nemavhola et al, 2021c;Nemavhola et al, 2021d;Ngwangwa et al, 2022). The data presented in this study covers the circumferential and longitudinal directions.…”

Section: Discussionmentioning

confidence: 94%

Experimental analysis and biaxial biomechanical behaviour of ex-vivo sheep trachea

Pandelani,

Ngwangwa,

Nemavhola

2023

Front. Mater.

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Besides surgery, there are currently no other established methods for routine treatment of tracheal pathologies such a tracheal stenosis or tracheal and airway tumors. Even with several attempts to repair the infected trachea with artificial and natural prostheses, there is a need for the fundamental understanding of the tissue’s mechanical behaviour. The purpose of this study was to investigate the mechanical behaviour of the tracheal tissue under biaxial tensile loading. Furthermore, the study examines the material properties of the tissue through a study of the model parameters for six constitutive models. Materials and methods: The fourteen (n = 14) specimens of sheep trachea (Vleis Merino) measured to be ∼30 × 20 mm where only the effective area of ∼25 × 16 mm was subjected to engineering strain. In this study, we assume that the tracheal tissue is anisotropic and incom-pressible, therefore we apply and study the material parameters from six different constitutive material models. Results: The results show that the tracheal tissue is twice as stiff along the circumferential direction as it is along the longitudinal direction. It is also observed that the material properties are different (non-homogeneous) along the trachea. Conclusion: The findings of this study will benefit computational models for the study of tracheal diseases or injuries. Furthermore, these findings will assist in the development of regenerative medicine for different tracheal pathologies and in the bioengineering of replacement tissue in cases of damage.

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Section: Discussionmentioning

confidence: 94%

Experimental analysis and biaxial biomechanical behaviour of ex-vivo sheep trachea

Pandelani,

Ngwangwa,

Nemavhola

2023

Front. Mater.

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Experimental analysis and biaxial biomechanical behaviour of ex-vivo sheep trachea

Ṋemavhola¹,

Ngwangwa²,

Pandelani

2021

Preprint

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PurposeThe purpose of this study is to investigate the mechanical behaviour of the tracheal tissue under biaxial tensile loading. Furthermore, the study examines the material properties of the tissue through a study of the model parameters for six constitutive models.Materials and methodsThe fourteen (n = 13) trachea sheep (Vleis Merino) pieces of tissues measured to be ~ 30 × 20 mm where only the effective area subjected to engineering strain was ~ 25 × 16 mm. In this study, we assume that the tracheal tissue is anisotropic and incompressible, therefore we apply and study the material parameters from six models namely the Fung, Choi-Vito, Holzapfel (2000), Holzapfel (2005), Polynomial (Anisotropic) and Four-Fiber Family models.ResultsThe results show that the trachea tissue is twice as stiff along the circumferential direction as it is along the longitudinal direction. It is also observed that the material properties are different (non-homogeneous) along the trachea.ConclusionsThe findings of this study will benefit computational models for the study of tracheal diseases or injuries. Furthermore, these findings will assist in the development of regenerative medicine for different tracheal pathologies and in the bioengineering of replacement tissue in cases of damage.

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Mathematical modeling of biomechanical elastic and hyperelastic properties of the myocardium

Muslov,

Vasyuk,

Zavialova

et al. 2024

Medical academic journal

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BACKGROUND: The study of mechanical properties of biological tissues is extremely informative and is one of the most important areas of biomechanics. Knowledge of these aspects of biological objects based on experimental data can become a source of new medical and technical solutions for the reconstruction of organs and the development of replacement materials. AIM: Passive mechanical properties of isolated myocardium are compared with linear, bilinear, exponential and the most common hyperelastic models (neohookean, Mooney–Rivlin, Ogden, Yeoh, polynomial and Veronda–Westmann). MATERIALS AND METHODS: Literature data on mechanical tests of autopsy material obtained from mongrel dogs were used as initial data. To search for the most advanced calculation algorithms the computer algebra system was used, the Mathcad 15.0 software package and the multifunctional finite element analysis application ANSYS 2022 R2 were used. Direct comparison of models was made based on mathematical statistics. RESULTS: Among the first group of models, the results closest to the experimental data were demonstrated by the exponential model R = 0.9958/0.9984 (in the longitudinal/transverse direction with respect to the myocardial fibers), the lowest accuracy was demonstrated by the linear model R = 0.9813/0.9803. Young’s moduli of linear, bilinear and exponential models and material constants of hyperelastic models are determined. The coefficient of elastic anisotropy of the myocardium, defined as the ratio of the elastic moduli of the linear model measured along and across the direction of the fibers, is equal to 2.18, which is very different from the literature data for the myocardium of the human heart. Deformation along the fibers of the heart muscle is more energy-consuming in the direction along the fibers than in the transverse direction (3.81 and 2.52 mJ/cm3). The most accurate hyperelastic models turned out to be the 2nd order polynomial model R = 0.9971 and the 3rd order Yeoh model R = 0.997. The largest deviations and the lowest correlation coefficient between the experimental and model data were demonstrated by the simple neohookean model R = 0.974 with a single parameter μ. The numerical values of the parameters of hyperelastic models obtained by calculation methods used practically did not differ from each other (≤2.16%). CONCLUSIONS: The study demonstrated the importance of selecting the correct mechanical model for isolated myocardium. The data obtained can be useful in virtual interventions (simulations) for predicting outcomes and supporting clinical decisions, developing replacement materials and structures made of them for reconstructive operations on heart structures.

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Fitting of Hyperelastic Constitutive Models in Different Sheep Heart Regions Based on Biaxial Mechanical Properties

Cited by 3 publications

References 37 publications

Experimental analysis and biaxial biomechanical behaviour of ex-vivo sheep trachea

Experimental analysis and biaxial biomechanical behaviour of ex-vivo sheep trachea

Experimental analysis and biaxial biomechanical behaviour of ex-vivo sheep trachea

Mathematical modeling of biomechanical elastic and hyperelastic properties of the myocardium

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