Key Takeaways & Executive Findings
- •• • Shock waves alone may not cause complete structural failure; bubble pulsation can induce strain growth exceeding shock wave effects, as observed in stiffened plates, necessitating combined load consideration in design. • • Underwater contact explosions can create breaches over ten meters in diameter in ship hulls, leading to dynamic buckling, tearing, and rapid flooding of multiple compartments, as evidenced by WWII data where 19 large ships were sunk by torpedoes. • • Multi-cabin protective structures, particularly liquid-filled compartments, effectively dissipate energy through fluid-structure interaction and impedance mismatch, reducing damage to inner bulkheads, as demonstrated in comparative studies of single vs. double liquid compartments. • • Composite materials and structures offer improved blast resistance but face challenges in scalability and integration into existing ship designs, requiring further research to optimize performance and cost-effectiveness.
Abstract
Underwater contact explosions from torpedoes and mines pose severe threats to ship survivability. The coupled effects of shock waves, bubbles, and secondary fragments induce complex structural damage. This review first analyzes the load characteristics of underwater contact explosions, detailing the spatial-temporal evolution of shock waves, bubbles, and secondary fragments. Subsequently, it examines protective mechanisms from two perspectives: multi-cabin structural protection and composite structure/material protection, focusing on damage suppression and energy dissipation. Finally, key technical challenges are summarized to guide future research. The review highlights that shock waves cause initial indentation and perforation of the outer plate, while bubble pulsation and collapse jets dominate subsequent large deformation and tearing of bulkheads. Experimental studies show that stiffened plates exhibit significant strain growth during bubble pulsation, potentially exceeding shock wave effects. Multi-cabin designs, such as liquid-filled compartments, effectively mitigate damage through energy absorption and impedance mismatch. Composite materials offer enhanced blast resistance but face scalability issues. The paper underscores the need for high-fidelity numerical methods and experimental validation to resolve controversies regarding dominant damage mechanisms. This work provides a comprehensive reference for advancing ship structural protection against underwater contact explosions.
1. Introduction
Underwater contact explosions represent a critical threat to naval vessels, with torpedoes and mines capable of inflicting catastrophic damage. The extreme loading conditions involve intense shock waves, non-spherical bubble dynamics, and high-velocity secondary fragments, all interacting with the hull structure in a highly nonlinear manner. Traditional protective designs, such as multi-cabin arrangements, have been developed based on empirical data from WWII and subsequent experiments, yet the underlying mechanisms remain incompletely understood. The complexity arises from the coupling of shock wave propagation through multi-phase media, bubble growth and collapse near deformable boundaries, and the generation of irregular fragments that penetrate internal compartments. These factors challenge existing analytical and numerical models, which often assume small deformations and neglect the progressive damage that occurs during the event.
This review addresses the bottleneck in current protective design by synthesizing recent advances in load characterization and structural response. It critically evaluates the roles of shock waves versus bubble pulsation in causing structural failure, a topic of ongoing debate. By examining experimental and numerical studies, the review identifies that bubble-induced loads can dominate late-stage damage, leading to extensive tearing and flooding. Furthermore, it assesses the efficacy of multi-cabin and composite protective systems, highlighting their energy dissipation mechanisms and limitations. The synthesis of these findings provides a framework for developing more resilient ship structures, emphasizing the need for integrated experimental-numerical approaches to capture the full spectrum of damage mechanisms.
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MING Furen, JIN Yuenan, ZHANG Bowen, ZHU Shipeng, JIANG Ruihan, ZHANG Nu, ZHANG Aman (2026). Review on Ship Structural Damage and Protection Subjected to Underwater Contact Explosions. Chinese Journal of Energetic Materials (含能材料). https://doi.org/10.11943/CJEM2026118
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Frequently Asked Questions
What are the dominant damage mechanisms in underwater contact explosions, and how do shock waves and bubble pulsation contribute to structural failure?
The dominant damage mechanisms involve an initial shock wave that causes indentation and perforation of the outer plate, followed by bubble pulsation and collapse jets that induce large deformation and tearing of inner bulkheads. Experimental studies show that stiffened plates exhibit significant strain growth during bubble pulsation, sometimes exceeding shock wave effects, indicating that bubble loads are critical for progressive damage. The relative contribution depends on the standoff distance and structural configuration, with contact explosions emphasizing bubble effects due to the proximity.
How effective are liquid-filled multi-cabin structures in mitigating damage compared to air-filled compartments?
Liquid-filled compartments are more effective due to their ability to absorb and dissipate energy through fluid-structure interaction and impedance mismatch. Comparative studies of single and double liquid compartments under contact explosions show that double liquid layers provide superior protection by reducing the transmitted impulse to inner bulkheads. The presence of liquid also alters bubble dynamics, reducing the intensity of collapse jets. However, the design must optimize liquid volume and compartment geometry to maximize energy dissipation without compromising structural integrity.
What are the limitations of current numerical methods in predicting structural response to underwater contact explosions?
Current numerical methods, such as ALE and SPH, face challenges in accurately capturing the multi-phase, multi-material interactions and the transition from intact to damaged structures. The extreme pressures and large deformations require fine mesh resolution and robust contact algorithms, which are computationally expensive. Additionally, the stochastic nature of secondary fragment generation and the coupling between bubble dynamics and structural failure are not fully resolved. Validation against experimental data is essential, but high-fidelity experiments are difficult due to measurement limitations in the near-field.
What are the scalability challenges for composite materials in ship protective structures?
Composite materials offer high specific strength and energy absorption, but scaling up to full ship sections presents challenges in manufacturing, joining, and cost. The anisotropic behavior and strain-rate sensitivity require careful characterization under blast loading. Additionally, the integration of composites with existing steel structures introduces galvanic corrosion and thermal expansion mismatches. While laboratory tests show improved blast resistance, the long-term durability and repair logistics in a naval environment remain uncertain, necessitating further research and cost-benefit analysis.
How do historical data and empirical formulas inform current protective design, and what are their limitations?
Historical data from WWII ship damage, such as the empirical formula by Yoshida for breach size, provide baseline estimates for design. However, these formulas are based on limited data and specific ship configurations, lacking generality for modern hull forms and explosive types. Semi-empirical models for plugging and petaling, such as those by Wierzbicki and Rajendran, offer insights but rely on simplified assumptions. Current design must integrate these with advanced numerical simulations and scaled experiments to account for complex geometries and loading scenarios, ensuring robustness against evolving threats.
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