Project Card 06

Finite Element Simulation of Femur or Pelvic Impact Injury Using Force-Based Criteria

Project Pathway

🟦 Numerical / Computational Modeling (FEM)

1. Background & Motivation

Injuries to the pelvis and lower extremities, particularly the femur, are common in automotive crashes, pedestrian impacts, falls, and industrial accidents. These injuries can lead to severe long-term disability and are therefore a major focus of trauma biomechanics and safety system design.

Unlike head or thoracic injuries, femur and pelvic injury assessment often relies on force-based injury criteria, reflecting the load-bearing role of these structures. Finite element (FE) modeling enables detailed investigation of load transfer, stress distribution, and sensitivity of injury metrics to impact conditions and modeling assumptions.

This project focuses on developing and using a simplified FE model of the femur or pelvis to study impact injury mechanisms and evaluate commonly used force-based injury criteria.

2. Core Biomechanical Question

How do impact conditions and modeling assumptions influence force-based injury criteria predicted by a simplified finite element model of the femur or pelvis?

3. Injury Mechanisms & Relevant Injury Criteria

The project should address the following biomechanical aspects:

• Lower extremity injury mechanisms:
  • Axial compression
  • Bending and shear
  • Load transmission through the pelvis or femur
• Impact scenarios relevant to automotive or pedestrian trauma

Relevant injury metrics may include:

• Femur axial force
• Femur Force Criterion (FFC)
• Pelvic compression force (conceptual discussion)
• Stress- or strain-based indicators (optional, with justification)

Students must justify the selection of injury criteria and explain their biomechanical relevance and limitations.

4. Modeling / Analysis Approach

This is a numerical FEM-based project using a simplified lower-extremity model.

The student is expected to:

• Develop or adapt a simplified FE model of the femur or pelvic structure
• Represent cortical and cancellous bone at a conceptual level
• Apply impact or compressive loading representative of traumatic events
• Extract and interpret force-based injury metrics

High anatomical detail is not required. Emphasis is placed on load paths, injury metrics, and interpretation.

5. Technical Specification (Core Section)

The project must include a clear and structured description of:

a) Geometry and Model Structure

• Choice of femur or pelvis geometry (simplified)
• Mesh type and resolution
• Justification of geometric simplifications

b) Material Modeling

• Material assumptions for bone (linear elastic or simplified nonlinear)
• Treatment of heterogeneity (if any)
• Rationale for parameter selection

c) Boundary Conditions and Loading

• Loading configuration (axial impact, bending, or combined loading)
• Impact velocity or applied force
• Constraints and contact definitions

d) Output Quantities

• Internal forces and reaction forces
• Force-based injury metrics (e.g., FFC)
• Stress or strain distributions (if used)

6. Parametric / Sensitivity Study

A limited parametric study is required, such as:

• Variation of impact velocity or loading magnitude
• Variation of bone stiffness or boundary conditions
• Comparison between different loading configurations

The goal is to assess relative trends and sensitivities, not precise fracture thresholds.

7. Validation Strategy & Limitations

The project must explicitly discuss:

• Comparison with published femur or pelvis impact tolerance data
• Sensitivity of injury predictions to modeling assumptions
• Limitations related to:
  • simplified geometry,
  • absence of fracture modeling,
  • lack of experimental validation

Students must clearly state what conclusions are justified by the model.

8. Feasibility & Computational Considerations

The project must address:

• Software used (e.g., Abaqus/Explicit, LS-DYNA)
• Computational cost and runtime
• Mesh density and timestep considerations
• Numerical stability under high loads

Overly complex fracture or damage models are discouraged.

9. Expected Outcomes

By the end of the project, the student should deliver:

• A simplified FE femur or pelvis impact model
• Computed force-based injury metrics for selected scenarios
• Sensitivity analysis results
• A critical interpretation of lower-extremity injury predictions

The outcome should demonstrate numerical competence and biomechanical reasoning.

10. Deliverables

1. Final Report (20-25 pages, excluding appendices)
2. Model description and representative figures
3. Injury metric plots and tables
4. Oral presentation (15-20 minutes)

Optional appendices:

• Input files
• Post-processing scripts
• Additional simulation cases

11. Project-Specific Grading Rubric

12. Project Scope Agreement

By choosing this project, the student agrees to:

• Focus on load-path interpretation, not fracture prediction
• Clearly document assumptions and limitations
• Avoid unjustified claims about injury thresholds

Note:
In lower-extremity trauma biomechanics, understanding force transmission is often more informative than predicting exact fracture locations.