Risk assessment study on the impact of sitting posture on lumbar vibration injury based on finite element method and neural network

Different driving postures may alter the impact of vibrations on the lumbar spine. This study explores the influence of posture on the lumbar spine by analyzing the risk of intervertebral disc vibration injury. Initially, Python language was utilized to develop code to obtain 48 different postural three-dimensional finite element models of the human-chair system. Subsequently, these models underwent harmonic response analyses at frequencies of 5, 7, and 9 Hz, with the maximum Von Mises stress on the L4–L5 intervertebral disc used to calculate the risk factor. Finally, a neural network model was trained using the frequency and posture angles as input values and the risk factor as the output values, enabling prediction of intervertebral disc risk factors in more precise sitting postures. The findings reveal that the posture of the upper body plays a primary role in influencing the lumbar spine, with the thigh posture having a greater impact when the upper body is closer to a vertical position, while the influence of the lower leg posture is minimal. Across all three frequencies, the optimal angle for the upper body is 109°, 109°, 115°, and for the thighs, it is 90°, 90°, 100°. A higher risk factor is observed when the upper body is angled between 90° and 100°. Conversely, an upper body angle between 110° and 120° is deemed acceptable. Vibration at 9 Hz had the greatest impact on the risk of lumbar injury when the upper body is in or close to a vertical sitting position.