NONLINEAR DYNAMIC CHARACTERISTICS OF LUMBAR DISC SUBJECTED TO STOCHASTIC EXCITATION

Abstract

The lumbar disc has complex structure and material properties, and if it develops disease, it cannot heal itself. Therefore, prevention of lumbar disc herniation is very important. In this paper, the model of lumbar disc is built, and the nonlinear dynamic response of the system is researched. A modified Van der Pol model is imported to describe the stress–strain curves of the lumbar disc. The system’s dynamic model is set up, and harmonic balance method is applied to revise the natural frequency of the system. The product of numerical simulation reveals that the lumbar disc has complex dynamic characteristics, including balance point, limit cycle bifurcation and stochastic Hopf bifurcation. By changing the parameters, we can avoid large-scale periodic movement of the lumbar disc which causes lumbar disc herniation. These results contribute to the prevention of lumbar disc herniation.