Dept. de Ingeniería Mecánica y de Materiales. Instituto de Ingeniería Mecánica y Biomecánica de Valencia - I2MB, Universitat Politècnica de València, Camino de Vera, Building 5E-9C, Valencia 46022, Spain.
Dept. de Ingeniería Mecánica y de Materiales. Instituto de Ingeniería Mecánica y Biomecánica de Valencia - I2MB, Universitat Politècnica de València, Camino de Vera, Building 5E-9C, Valencia 46022, Spain.
Comput Methods Programs Biomed. 2022 Jun;219:106764. doi: 10.1016/j.cmpb.2022.106764. Epub 2022 Mar 21.
Elastic and strength properties of lamellar tissue are essential to analyze the mechanical behaviour of bone at the meso- or macro-scale. Although many efforts have been made to model the architecture of cancellous bone, in general, isotropic elastic constants are assumed for tissue modelling, neglecting its non-isotropic behaviour. Therefore, isotropic damage laws are often used to estimate the bone failure. The main goals of this work are: (1) to present a new model for the estimation of the elastic properties of lamellar tissue which includes the bone mineral density (BMD) and the microporosity, (2) to address the numerical modelling of cancellous bone damage using an orthotropic failure criterion and a discrete damage mechanics analysis, including the novel approach for the tissue elastic properties aforementioned.
Numerical homogenization has been used to estimate the elastic properties of lamellar bone considering BMD and microporosity. Microcomputed Tomography (μ-CT) scans have been performed to obtain the micro-finite element (μ-FE) model of cancellous bone from a vertebra of swine. In this model, lamellar tissue is orientated by considering a unidirectional layer pattern being the mineralized collagen fibrils aligned with the most representative geometrical feature of the trabeculae network. We have considered the Hashin's failure criterion and the Material Property Degradation (MPDG) method for simulating the onset and evolution of bone damage.
The terms of the stiffness matrix for lamellar tissue are derived as functions of the BMD and microporosity at tissue scale. Results obtained for the apparent yield strain values agree with experimental values found in the literature. The influence of the damage parameters on the bone mechanics behaviour is also presented.
Stiffness matrix of lamellar tissue depends on both BMD and microporosity. The new approach presented in this work enables to analyze the influence of the BMD and porosity on the mechanical response of bone. Lamellar tissue orientation has to be considered in the mechanical analysis of the cancellous bone. An orthotropic failure criterion can be used to analyze the bone failure onset instead of isotropic criteria. The elastic property degradation method is an efficient procedure to analyze the failure propagation in a 3D numerical model.
板层组织的弹性和强度特性对于分析中观或宏观骨骼的力学行为至关重要。尽管已经做出了许多努力来模拟松质骨的结构，但通常情况下，组织建模都会假设各向同性弹性常数，而忽略其各向异性行为。因此，各向同性损伤法则通常用于估计骨骼失效。这项工作的主要目标是：（1）提出一种新的模型，用于估计包括骨密度（BMD）和微孔率的板层组织的弹性特性；（2）使用各向异性失效准则和离散损伤力学分析来解决松质骨损伤的数值建模问题，包括上述组织弹性特性的新方法。
使用数值均匀化方法来估计考虑 BMD 和微孔率的板层骨的弹性特性。进行了微计算机断层扫描（μ-CT）扫描，以从猪的椎骨获得松质骨的微有限元（μ-FE）模型。在该模型中，板层组织通过考虑单向层模式进行取向，其中矿化的胶原纤维与小梁网络的最具代表性的几何特征对齐。我们考虑了 Hashin 的失效准则和材料性能退化（MPDG）方法来模拟骨骼损伤的开始和演化。
板层组织的刚度矩阵项被推导为组织尺度上的 BMD 和微孔率的函数。得出的表观屈服应变值与文献中发现的实验值吻合。还介绍了损伤参数对骨骼力学行为的影响。
板层组织的刚度矩阵取决于 BMD 和微孔率。本文提出的新方法可用于分析 BMD 和孔隙率对骨骼力学响应的影响。在松质骨的力学分析中必须考虑板层组织的取向。各向异性失效准则可用于分析骨骼失效的开始，而不是各向同性准则。弹性特性退化方法是分析 3D 数值模型中失效传播的有效程序。
