Study On Riding Comfort Based On Finite Element Analysis Of Humar Lumbar Spine

Seat is a main component in a motor train unit to directly guarantee the crew’s confort. The human spinal column can provide an optimal shock-absorption. At the same time an incorrect seated posture will make the vertebra have an offset from the natural physiological position. This will make a physiological pain and a psychological tiredness. An incorrect long-term seated posture will make the spinal column have a chronic. Therefore, it is especially important to study riding comfort by the current finite element method (FEM) with the knowledge of spinal biomechanics.First, this thesis uses Mimics to extract the point cloud data of L3-L5lumbar vertebral segments based on the CT’s data. The human vertebrae surface is synthesized by using Imageware software, and the three-dimensional solid model is generated from Pro/E. With the accurate physical model, we can improve the reliability and validity of the results.Then, this thesis imports model data to ANSYS through an interface between Pro/E and ANSYS. The discs, ligamentscan can also be made3-D entities. Different material is assigned different mechanical parameters, and the3-D entities are meshed to constructe a finite element model of L3-L5lumbar vertebral segments. To evaluate the stress distribution under different sitting posture, we simulate the typical riding posture, and it can provide a basis for the static seat comfort design.At last, this thesis carries out modal analysis for the L3-L4, L4-L5single motion segments and the L3-L5multi-motion segments, and extracts the former22-order modal shapes and frequencies separately. Through this we can find the difference between single motion segments and multi-motion segments in natural frequency also lay the foundation for dynamic response analysis. This thesis simulates the impact of the external harmonic excitation on lumbar vertebral segments, in order to propose the design of dynamic seat comfort.Biomechanics and finite element theory are used in this thesis, combined with modern CT and reverse engineering, some new conceptions about comfort design are suggested, which will be beneficial for the design of a motor train unit seat.