Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control, School of Mechanical Engineering, Tianjin University of Technology, Tianjin, China.
National Demonstration Center for Experimental Mechanical and Electrical Engineering Education (Tianjin University of Technology), Tianjin, China.
Biomed Eng Online. 2019 Jul 30;18(1):85. doi: 10.1186/s12938-019-0705-7.
Ratcheting strain is produced due to the repeated accumulation of compressive strain in cartilage and may be a precursor to osteoarthritis. The aim of this study was to investigate the ratcheting behaviors of young and adult articular cartilages under cyclic compression by experiments and theoretical predictions.
A series of uniaxial cyclic compression tests were conducted for young and adult cartilage, and the effects of different loading conditions on their ratcheting behaviors were probed. A theoretical ratcheting model was constructed and applied to predict the ratcheting strains of young and adult cartilages with different loading conditions.
Ratcheting strains of young and adult cartilages rapidly increased at the initial stage, followed by a slower increase in subsequent stages. The strain accumulation value and its rate for young cartilage were greater than them for adult cartilage. The ratcheting strains of the two groups of cartilage samples decreased with increasing stress rate, while they increased with increasing stress amplitude. As the stress amplitude increased, the gap between the ratcheting strains of young and adult cartilages increased gradually. The ratcheting strains of young and adult cartilages decreased along the cartilage depth from the surface to the deep layer. The ratcheting strains of different layers increased with the compressive cycle, and the difference among the three layers was noticeable. Additionally, the theoretical predictions agreed with the experimental data.
Overall, the ratcheting behavior of articular cartilage is affected by the degree of articular cartilage maturation.
由于软骨中压缩应变的反复累积，棘轮应变会产生，并且可能是骨关节炎的前兆。本研究旨在通过实验和理论预测来研究年轻和成年关节软骨在循环压缩下的棘轮行为。
对年轻和成年软骨进行了一系列单轴循环压缩试验，并探讨了不同加载条件对其棘轮行为的影响。构建了一个理论棘轮模型，并将其应用于预测不同加载条件下年轻和成年软骨的棘轮应变。
年轻和成年软骨的棘轮应变在初始阶段迅速增加，随后在随后的阶段增加较慢。年轻软骨的应变累积值及其速率大于成年软骨。两组软骨样本的棘轮应变随应力率的增加而减小，而随应力幅度的增加而增加。随着应力幅度的增加，年轻和成年软骨的棘轮应变之间的差距逐渐增大。年轻和成年软骨的棘轮应变从表面到深层沿软骨深度逐渐减小。不同层的棘轮应变随压缩循环而增加，并且三层之间的差异明显。此外，理论预测与实验数据吻合良好。
总体而言，关节软骨的棘轮行为受关节软骨成熟度的影响。
