兔单椎轴向动态冲击的实验研究

目的通过对兔单椎进行动态冲击破坏试验,并与静态压缩实验进行对比,研究椎体轴向冲击的损伤机制。方法通过落锤动态冲击实验装置,利用示波器和高速摄影获得力传感器的电压波形图和椎体冲击的详细过程。结果胸、腰椎平均静态载荷分别为910、947 N,平均动态载荷分别为1 196、1 026 N;胸、腰椎平均动荷系数分别为1.37和1.08。静载条件下,胸、腰椎平均等效应力为15.28、12.51 MPa;动载条件下,胸、腰椎平均等效应力20.03、13.56 MPa。动态冲击过程中,纵向、横向平均应变分别为-0.3和-0.005(压缩);动载条件下,椎骨的破坏能量从0 J一直增大到4.4 J。结论在动、静态实验条件下,同一椎体动态载荷大于静态载荷;胸椎平均动荷系数大于腰椎;胸椎应力大于腰椎;椎体受到轴向冲击力时纵向应变大于横向应变;椎体能量增长呈现先缓慢后快速的过程。研究结果可以为临床人脊柱椎体损伤的预防和康复提供指导意见。

Experimental Study on Axial Dynamic Impact of Rabbit Single Vertebra

Objective To conduct dynamic impact failure test of rabbit single vertebra, and make comparison with the static compression experiment, so as to study damage mechanism of the vertebral body under the axial impact. Methods The voltage waveform diagram of the force sensor and the detailed process of the vertebral impact were obtained by the oscilloscope and high-speed photography through the drop hammer dynamic impact experimental device. Results The average static load of the thoracic and lumbar vertebra were 910 N and 947 N, respectively; the average dynamic load of the thoracic and lumbar vertebra were 1 196 N and 1 026 N, respectively; the average thoracic and lumbar dynamic load coefficients were 1.37 and 1.08; under static load, the average stress of the thoracic and lumbar vertebra was 15.28 MPa and 12.51 MPa, respectively; under dynamic load, the average stress of the thoracic and lumbar vertebra was 20.03 MPa and 13.56 MPa; during dynamic impact, the mean longitudinal strain and transverse strain was -0.3 and -0.005 (compression); under dynamic conditions, the destruction energy of vertebrae increased from 0 J to 4.4 J. Conclusions Under dynamic and static experimental conditions, the dynamic load of the same vertebral body was greater than that of the static load; the average dynamic load coefficient of the thoracic vertebra was larger than that of the lumbar vertebra; the equivalent stress of the thoracic vertebra was greater than that of the lumbar vertebra; the axial strain of vertebra under impact was greater than the transverse strain; energy growth of the vertebral body presented a slow at first and then a rapid changing process. The research findings can provide some guidance for prevention and rehabilitation of human vertebral body injury in clinic.