Zambrano M Lilibeth A, Famaey Nele, Gilchrist Michael, Annaidh Aislin Ní
Aerospace and Mechanical Engineering Department, South East University of Ireland, Carlow, Ireland; School of Mechanical and Materials Engineering, University College Dublin, Dublin, Ireland.
BioMechanics (BMe) KU Leuven, Leuven, (Arenberg), Belgium.
J Mech Behav Biomed Mater. 2025 Mar;163:106821. doi: 10.1016/j.jmbbm.2024.106821. Epub 2024 Nov 20.
The mechanical properties of the human skull have been examined and established previously in the literature, for example, the transversal isotropy of cranial bone and properties including the Elastic modulus and Poisson's ratio. However, despite the existing data, there are still mechanical properties which remain to be determined for the human skull. The present study aims to characterise the fracture properties of human cranial bone within the Linear Elastic Fracture Mechanics (LEFM) framework. Unembalmed human (2 female and 3 male) cortical cranial bone samples were harvested from the frontal, and left and right parietal bones and were tested in Mode I (N = 124), Mode II (N = 31) and Mixed-Mode I-II (N = 47) loading conditions. For Mode I, samples were tested using Single Edge Notched Beams (SENB) under symmetric 3-point bending, while for Mixed-Mode I-II samples were tested under asymmetric 3-point bending. For Mode II, 4-point bend tests were carried out. All samples fractured in a brittle fashion. From these tests, reference values of stress intensity factor (K and K) and the strain energy release rate (J, G, G, G) for the frontal, left and right parietal bones were calculated. It was determined that the fracture toughness of the frontal, and left and right parietal bones are not statistically different from each other and that they exhibit symmetry about the sagittal plane. It was also demonstrated that, as is the case for other human bones and for the age range tested here, the fracture toughness of human cranial bone is lower for females (Kfemale 2.48 (±2.16) MPa∗m, Kmale 4.75 (±2.58) MPa∗m, Gfemale 1.07 (±3.01) kJ/m, Gmale 1.85 (±1.93) kJ/m, Jfemale 1.57 (1.89) kJ/m and Jmale 4.03 (±3.32) kJ/m) and varies with age. More experimental work should be carried out to confirm the extrapolation of these conclusions to the other fracture modes tested here. Although these results are influenced by the age range and the age gap within the group of donors, the primary data presented here is valuable to those wishing to predict crack evolution and propagation in the human cranial bone and may prove useful in developing failure criterion or simulations of skull fracture using Finite Element Analysis.
人类颅骨的力学性能此前已在文献中得到研究和确定，例如颅骨的横向各向同性以及包括弹性模量和泊松比在内的性能。然而，尽管已有相关数据，但人类颅骨仍有一些力学性能有待确定。本研究旨在在线性弹性断裂力学（LEFM）框架内表征人类颅骨的断裂特性。从不曾防腐处理的人类（2名女性和3名男性）颅骨皮质样本中获取额骨、左右顶骨样本，并在I型（N = 124）、II型（N = 31）和I-II混合型（N = 47）加载条件下进行测试。对于I型，样本采用单边切口梁（SENB）在对称三点弯曲下进行测试，而对于I-II混合型样本则在非对称三点弯曲下进行测试。对于II型，进行四点弯曲试验。所有样本均呈脆性断裂。通过这些测试，计算出了额骨、左右顶骨的应力强度因子（K和K）以及应变能释放率（J、G、G、G）的参考值。研究确定，额骨、左右顶骨的断裂韧性在统计学上并无差异，且它们关于矢状面呈对称分布。研究还表明，与其他人类骨骼以及此处测试的年龄范围情况相同，人类颅骨的断裂韧性在女性中较低（女性K值为2.48（±2.16）MPa∗m，男性K值为4.75（±2.58）MPa∗m，女性G值为1.07（±3.01）kJ/m，男性G值为1.85（±1.93）kJ/m，女性J值为1.57（1.89）kJ/m，男性J值为4.03（±3.32）kJ/m），并且随年龄变化。应开展更多实验工作以确认这些结论能否外推至此处测试的其他断裂模式。尽管这些结果受到供体组内年龄范围和年龄差距的影响，但此处呈现的原始数据对于那些希望预测人类颅骨裂纹演变和扩展的人来说是有价值的，并且可能在制定失效准则或使用有限元分析模拟颅骨骨折方面证明是有用的。
