Session: ASME Undergraduate Student Design Expo

Paper Number: 176165

Development and Validation of a Lumbar Spine Model for Vibration Analysis 

Introduction: Prolonged exposure to vehicular vibration has long been recognized as a critical occupational risk factor for lower back pain and spinal injury. Individuals working in transportation, construction, agriculture, and heavy machinery industries are particularly vulnerable, as daily exposure to vibration can accelerate spinal degeneration and contribute to chronic musculoskeletal disorders. Despite decades of epidemiological and experimental studies, the underlying biomechanical mechanisms of vibration-induced spinal injury remain insufficiently understood. Computational modeling provides a powerful approach for bridging this knowledge gap by enabling controlled, ethical, and repeatable investigations of tissue-level responses that are otherwise difficult to measure in vivo. The objective of this research is to develop and validate a finite element (FE) model of the human lumbar spine, focusing on the L1–L5 region, to investigate spinal response under vibration-induced loading and to establish a framework for predicting potential injury mechanisms.

This study contributes to advancing both computational biomechanics and occupational health by creating a lumbar-specific FE model that offers a balance between fidelity and computational efficiency. Rather than relying on full-body human models, which are resource-intensive and less practical for targeted studies, this focused approach enables detailed analysis of stress, strain, and displacement in the lumbar vertebrae, intervertebral discs, and supporting ligaments. By adapting an established FE model for use in new computational environments, this research also demonstrates a methodological advancement in multiscale modeling workflows. Ultimately, the validated model will serve as a versatile tool with applications in automotive safety design, ergonomic evaluation, and clinical decision-making.

Methodology: The lumbar model was developed by extracting the spine components from the Total Human Model for Safety (THUMS), originally implemented in LS-DYNA, converted to NASTRAN, and subsequently adapted for use in Abaqus to support multiscale computational frameworks. The L1–L5 segment was anatomically isolated, including vertebrae, intervertebral discs, and key spinal ligaments. Physiological boundary conditions were imposed by constraining the superior endplate of L1 and the inferior endplate of L5, replicating thoracolumbar and lumbosacral attachment. Simulations were conducted under controlled conditions, where translational motion was restricted in the X and Y directions while maintaining freedom in the Z axis to reflect axial loading. Dynamic loading inputs included simplified sinusoidal acceleration profiles to establish baseline responses, with ongoing implementation of complex road-graph-based vibration profiles to replicate real-world vehicular conditions. Model outputs captured displacements, stresses, and strains, with a focus on the intervertebral discs and vertebral bodies.

Preliminary Results: Preliminary results demonstrated that sinusoidal loading produced measurable displacements and stress distributions aligned with the direction of applied vibration. Stress concentrations were particularly pronounced in the intervertebral discs, whereas vertebral bodies experienced lower, more evenly distributed stresses. These findings are consistent with experimental data reported in the literature, reinforcing the role of intervertebral discs as primary load-bearing structures susceptible to vibration-induced damage. Validation efforts are ongoing, using both published biomechanical datasets and vibration measurements collected independently at the L1–L5 region. Early comparisons indicate that the model accurately reproduces trends observed in experimental studies, supporting its potential reliability as a predictive tool.

Conclusions: This research demonstrates the feasibility and utility of a lumbar-specific FE model adapted from the THUMS model for analyzing the spine biomechanical response to vibration. By isolating the L1–L5 region, the model reduces computational demand while preserving essential anatomical and mechanical fidelity. The results underscore the importance of intervertebral discs as critical sites of injury under vibration and highlight the broader value of computational approaches for addressing occupational health risks. Once fully validated with complex loading scenarios, the model will provide a foundation for developing ergonomic guidelines, informing safety regulations, and designing targeted interventions to reduce the prevalence of vibration-induced spinal disorders.

Presenting Author: Abdulrehman Nagi Mississippi State University

Presenting Author Biography: Abdulrehman Nagi is an undergraduate researcher at the Center for Advanced Vehicular Systems at Mississippi State University, working under the mentorship of Dr. Raheleh Miralami. His research focuses on finite element simulations of the lumbar spine to investigate how mechanical vibrations contribute to spinal injury.

Authors:

Abdulrehman Nagi Mississippi State University
Michael Murphy Mississippi State University
Raheleh Miralami Mississippi State University