Improved Crashworthiness of Automotive A-Pillars Through Hybrid Composite Reinforcement: An Experimental Study on Tensile and Compressive Performance

Abstract

This study investigates the structural enhancement of automotive A-pillars using a hybrid composite filler composed of epoxy resin, hardener, crushed wood, and glass fibre. The research compares the mechanical performance of hollow mild steel tubes with their composite-filled counterparts through rigorous tensile and compression testing. The Result demonstrated a 23.6% improvement in tensile strength and a 25.6% increase in compressive load capacity for the composite-filled specimens, along with superior energy absorption and controlled deformation. These findings highlight the potential of hybrid composites to optimize crashworthiness while maintaining lightweight design principles, offering significant implications for automotive safety engineering.

Introduction

The study focuses on improving the structural performance of automotive A-pillars—key components in vehicle safety—by using a hybrid composite filler. Traditional A-pillars made from hollow steel are strong but heavy, which affects fuel efficiency. To address this, the research investigates composite-filled A-pillars, using a hybrid mix of epoxy resin, crushed wood, and glass fiber to enhance strength while reducing weight.

Objectives of the Study:

1. Evaluate tensile and compressive performance of composite-reinforced A-pillars.

2. Analyze failure modes and energy absorption.

3. Offer insights for automotive designers balancing strength and weight.

Materials and Methods:

• Mild steel tubes (25.4 mm × 25.4 mm × 0.8 mm wall thickness) were used.

• Tubes were either left hollow or filled with a composite mix (epoxy resin + hardener + glass fiber + crushed wood).

• Fabrication included cutting, shaping, welding steel tubes, pouring in the filler, and curing for 15 days.

Experimental Setup:

• Tests conducted on a Universal Testing Machine (UTM).

• Two test types:

  • Tensile testing (per ASTM D3039): measured max load, elongation, yield strength.

  • Compression testing (per ASTM E9): measured load capacity, buckling behavior, shape retention.

Tensile Test Results:

• Composite-filled A-pillars showed:

  • ~23.6% higher max load (24.4 kN vs. 19.74 kN).

  • ~19% higher tensile strength (39.09 MPa vs. 32.91 MPa).

  • Much lower ductility (4% elongation vs. 45% for hollow steel).

• Failure mode: Hollow tubes showed ductile necking; composite tubes failed abruptly, indicating higher strength but brittleness.

Compression Test Results:

• Composite-filled specimens had:

  • ~25.6% higher compressive load capacity (33.72 kN vs. 26.85 kN).

  • More controlled, gradual deformation compared to the sudden buckling in hollow specimens.

  • Greater post-failure shape retention (~80% vs. ~25% for hollow steel).

• Failure mode: Hollow tubes failed via sudden buckling; composite-filled tubes resisted deformation longer and collapsed progressively.

Key Findings:

• The hybrid filler significantly improves both tensile and compressive strength.

• Trade-off: Strength increases at the expense of ductility (less deformation before failure).

• The filler enhances load distribution, delays failure, and improves crashworthiness.

• The approach offers a feasible, lightweight, and stronger alternative for automotive A-pillar design, beneficial for safety and fuel efficiency.

Conclusion

The results showed the feasibility and benefits of using epoxy-based composite fillers in tubular steel A-pillars to enhance its mechanical properties. The hybrid configuration improves the tensile and compressive performance while maintaining a lightweight design, suggesting its potential for automotive crash-resistant components. These performance improvements align with broader trends in automotive materials engineering, as noted by in their review of multiphase composites. However, the trade-off between strength and ductility requires further investigation, as observed in. Future research could explore thermoplastic matrices or alternative fibre architectures to mitigate ductility loss while preserving strength gains.The results validated hybrid composites as a viable solution for A-pillar reinforcement, offering measurable crashworthiness improvements. Given the importance of weight savings in electric vehicles, these findings support industry adoption, highlighting the need for further optimization. To summaries, this study investigates the structural enhancement of automotive A-pillars using a hybrid composite filler, demonstrating a 23.6% improvement in tensile strength and a 25.6% increase in compressive load capacity, highlighting the potential of hybrid composites to optimize crashworthiness while maintaining lightweight design principles.

References

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Copyright

Copyright © 2025 Arjun Alias Ajay U. Shimpi, Kedar H. Inamdar , Aniket C. Patil. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.