Zhuojin Pipe Fitting Co., LtdContact Explosion Resistance of Steel Plate Sandwiched Steel Tube Composite Panels
Literature Overview
This research, published in Journal of Vibration and Shock (Vol. 36, No. 8, 2017, pp. 149–155) by Xia Zhicheng, Wang Xihao, Zhao Yueting, Gong Ziming, and Kong Xinli from the College of National Defence Engineering, National University of Defence Technology, investigates the blast resistance of a novel sandwich composite panel structure consisting of face plates separated by a steel tube core layer. Supported by a National Natural Science Foundation project (51478469), this study addresses the important engineering challenge of protecting structures against contact detonation threats through innovative structural design.
Core Technical Content
Structural Design Concept
The sandwich composite panel employs a layered configuration of steel plate–steel tube core–steel plate, combining the advantages of:
- Face plates: provide initial resistance and distribute blast pressure
- Steel tube core: provides energy absorption through plastic deformation and maintains separation between face plates
- Sandwich architecture: provides superior strength-to-weight ratio compared to monolithic plates
This design philosophy leverages the well-established principle that sandwich structures achieve higher bending stiffness and energy absorption capacity than monolithic structures of equivalent weight, while the tubular core elements specifically exploit the high ductility and progressive collapse characteristics of steel tubes under compressive loading.
Experimental Programme
Three configurations were tested, varying the number of steel tube core elements:
| Configuration | Core Tube Count | TNT Charge | Test Type |
|---|---|---|---|
| Panel A | 5 tubes | 1 kg | Contact detonation |
| Panel B | 4 tubes | 1 kg | Contact detonation |
| Panel C | 3 tubes | 1 kg | Contact detonation |
Key Experimental Findings
- Deformation mode: The composite panels primarily undergo localised compressive deformation under contact blast loading, with the steel tube core elements buckling and crushing in a progressive manner.
- Energy dissipation mechanism: The steel tube core deformation constitutes the primary pathway for energy dissipation in the composite panel system, effectively converting blast kinetic energy into plastic deformation energy.
- Design parameter effects:
- Increasing the number of core tubes reduces deformation and improves blast resistance
- Increasing face plate thickness reduces deformation and improves blast resistance
- Increasing tube wall thickness reduces deformation and improves blast resistance
Theoretical and Numerical Analysis
The study complemented experimental results with theoretical analysis and numerical simulation to:
- Validate the experimental observations
- Predict performance for untested parameter combinations
- Understand the deformation and failure sequence in detail
- Provide a basis for optimising the panel design
Engineering Practice Implications
Steel Tube Fabrication Requirements
For the core tubes in blast-resistant sandwich panels, the following fabrication quality requirements are critical:
- Uniform wall thickness: Non-uniform wall thickness creates weak spots that initiate premature buckling, reducing overall energy absorption capacity
- Surface quality: Surface defects (scratches, dents, weld marks) act as stress concentrators and can trigger localised failure
- Microstructural uniformity: Inconsistent heat treatment can create soft zones that fail prematurely under compressive loading
- Dimensional accuracy: Tube diameter and straightness must be controlled to ensure uniform load distribution across the core layer
Material Selection Considerations
| Material Property | Design Priority | Reasoning |
|---|---|---|
| Yield strength | Moderate (not excessively high) | Allows controlled plastic deformation for energy absorption |
| Strain hardening exponent | High | Provides progressive resistance during deformation |
| Fracture strain | High | Ensures complete crushing before separation |
| Toughness | Adequate | Prevents brittle fracture during dynamic loading |
| Fatigue resistance | Secondary | Static/impulsive loading dominates |
Design Optimisation Strategy
The parametric study provides clear guidance for engineers designing blast-resistant sandwich panels:
- For a given blast threat level, select the minimum number of core tubes that achieves the required performance, as additional tubes increase weight and cost.
- Prioritise face plate thickness over tube wall thickness when both are variable, as the face plate directly interacts with the blast wave.
- Ensure adequate spacing between core tubes to prevent stress concentration at the face plate-to-tube interface.
Study Insights and Reflections
This research demonstrates the practical viability of steel tube core sandwich panels as blast-resistant protective structures. The key insight for steel tube manufacturers and structural engineers is that the energy absorption capacity of the core tubes depends not only on their geometric parameters but also on the controlled plasticity of the material. For steel tube producers, this opens a market opportunity for specially specified tubes with optimised strain hardening behaviour rather than maximum strength. The progressive crushing behaviour of the steel tube cores provides predictable energy dissipation, which is advantageous for structural design because the load-deflection response can be accurately modelled. Future work should address the multi-event response (residual strength after initial blast) and the effects of varying blast charge weights and standoff distances on the panel performance, as these represent realistic design scenarios that extend beyond the single-event contact detonation tested in this study.