Material Parameter Determination of an L4-L5 Motion Segment Finite Element Model Under High Loading Rates

Area of Science:

• Biomechanics
• Spinal Injury Research
• Finite Element Modeling

Background:

• Underbody blast (UBB) events cause severe lumbar spine injuries.
• Previous research focused on quasi-static loading, leaving dynamic responses unclear.
• Understanding dynamic component behavior is crucial for injury prevention.

Purpose of the Study:

• To develop and validate a high-fidelity finite element model of the lumbar spine for underbody blast (UBB) events.
• To characterize the dynamic material properties of individual spinal components.
• To improve the prediction of lumbar spine injuries during high-rate impacts.

Main Methods:

• Utilized high-rate impacts on dissected lumbar motion segments.
• Employed Split-Hopkinson pressure bar testing for tissue characterization.
• Modeled annulus fibrosus as fiber-reinforced Mooney-Rivlin and ligaments as nonlinear springs.
• Optimized material parameters by minimizing root-mean-square error in displacement and rotation.

Main Results:

• Achieved a 0.42% difference between predicted and experimental axial compression during impact.
• Successfully validated material properties for a dynamic lumbar spine model.
• Demonstrated the model's capability to simulate high-rate impact loading.

Conclusions:

• The dynamically optimized lumbar spine model accurately predicts response to UBB loading.
• This model is suitable for cross-validation and injury prediction in dynamic scenarios.
• Enhances understanding of lumbar spine mechanics under blast conditions.