摘要:
皮质骨作为人体骨骼系统的重要组成部分,能有效分散与吸收外部冲击力,保护内部骨髓腔、周围软组织和器官不受损伤。为研究冲击载荷作用下皮质骨力学响应,借助万能材料试验机、分离式霍普金森压杆(Split Hopkinson Pressure Bar, SHPB)装置对猪皮质骨开展了不同应变率下准静态与动态压缩实验。采用超景深三维显微系统和数字图像相关(Digital Image Correlation, DIC)技术观察了皮质骨压缩形变特征,利用含损伤的黏弹性本构模型对实验数据进行了拟合,确定了模型中本构参数。结果表明,皮质骨压缩过程体现为骨质裂纹的产生与扩展,其力学性能具有明显的应变率相关性,弹性模量、屈服应力和压缩强度随应变率的增加而显著提高。准静态加载时,应力-应变曲线包括弹性变形和塑性变形阶段;高应变率加载时,应力-应变曲线在应变小于0.2%时为弹性,随着压缩量增加呈现高度的非线性,无显著塑性变形,展现一定的黏弹性特征。通过实验曲线与本构模型理论曲线对比,理论值与实验值误差较小,能准确描述皮质骨在不同应变率下压缩力学行为,研究成果为人体冲击伤的救治与防护设计提供理论参考。
关键词:
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皮质骨 /
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冲击载荷 /
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黏弹性 /
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应变率 /
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本构模型
Abstract:
The cortical bone, an essential component of the human skeletal system, effectively disperses and absorbs external impact forces, protecting the internal bone marrow cavity, surrounding soft tissues, and organs from damage. To investigate the mechanical response of cortical bone under impact loading, quasi-static and dynamic compression experiments were conducted on porcine cortical bone at different strain rates using a universal materials testing machine and a Split Hopkinson Pressure Bar (SHPB) apparatus. Observations of the deformation characteristics of the cortical bone under compression were made using a super-depth-of-field 3D microscopic system and Digital Image Correlation (DIC) technology. The experimental data was fitted using a viscoelastic constitutive model that accounts for damage, to determine the constitutive parameters within the model. The results indicate that the compression process of cortical bone is characterized by the initiation and propagation of bone cracks, with its mechanical properties showing significant strain rate dependency. Both elastic modulus, yield stress, and compressive strength increase markedly with the rise in strain rate. Under quasi-static loading, the stress-strain curve includes stages of elastic and plastic deformation; whereas under high strain rate loading, the stress-strain curve remains elastic until strains less than 0.2%, after which it exhibits pronounced nonlinearity as the compression increases, without evident plastic deformation, revealing certain viscoelastic features. Comparing the experimental curves with theoretical curves derived from the constitutive model, the discrepancy between theoretical values and experimental values is minimal, accurately describing the compressive mechanical behavior of cortical bone at different strain rates. This research provides valuable theoretical reference for the treatment and protective design against human impact injuries. This translation conveys the scientific study's setup, methodology, findings, and implications regarding the mechanical behavior of cortical bone under varying conditions of strain rates, emphasizing the importance of this knowledge for medical applications.