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Optimization of a Small-Scale Submersible Composite Hull Subjected to Underwater Explosion

Background. One of the requirements of designing underwater vehicles for use in hostile environments is to provide a certain degree of resistance to shock waves due to noncontact underwater explosionsHeavy hull structure is inherently resistant to a variety of different explosion events.For miniat

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Optimization of a Small-Scale Submersible Composite Hull Subjected to Underwater Explosion

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    1. Optimization of a Small-Scale Submersible Composite Hull Subjected to Underwater Explosion Leonard J. Askinazy Engineering Project Fall 2010

    2. Background One of the requirements of designing underwater vehicles for use in hostile environments is to provide a certain degree of resistance to shock waves due to noncontact underwater explosions Heavy hull structure is inherently resistant to a variety of different explosion events. For miniature submersibles, the use of heavy hull structure can seriously impact potential payload and crew capacity. Overall weight can be reduced with the use of composite materials.

    3. Objective Using finite element analysis, investigate whether a small-scale composite submersible model can provide satisfactory shock resistance as compared to isotropic configurations.

    4. Assumptions Underwater explosions generate shock waves and form a superheated, highly compressed gas bubble. Since most damage to structure backed by water occurs early due to the shock wave, only this damage will be considered. Other loading requirements, such as submergence, will not be considered in the optimization process. Effects of the free surface or seabed on the reflection of pressure waves will not be considered, only the fluid-structure interaction between the structure and the surrounding water.

    5. Structural Model

    6. Fluid Representation

    7. Sandwich Honeycomb Panel In [5], Kalavalapally optimized a FEM of a lightweight torpedo concept of size comparable to MSV for resistance to underwater shock using a sandwich honeycomb panel as shown below

    8. Ply Thicknesses (from optimized torpedo)

    9. Explosion Scenario of MSV

    10. Processing Results in ABAQUS ABAQUS has the capability to evaluate, for each ply, a multitude of failure criteria simultaneously for each simulation, including maximum stress, maximum strain, Tsai-Wu, and Tsai-Hill criteria.

    11. Pressure Profile surrounding MSV

    12. Failure Criteria Results (Tsai-Hill), Sandwich Honeycomb

    13. Findings and Alternative Materials to be Explored Sandwich-Stiffened Honeycomb: satisfies first-ply failure criteria, absorbs more energy of pressure wave than steel due to higher velocity distribution along hull Graphite-epoxy: Progress: simulations run, however optimal design not yet achieved Additional filament-wound multilayer sandwich structures

    14. Future Tasks Continue to optimize performance and weight of composite structure Final Validation and Documentation

    15. References C.Y. Jen, “Coupled acoustic-structural response of optimized ring-stiffened hull for scaled down submerged vehicle subject to underwater explosion, Theoretical and Applied Mechanics 52 (2009),” 96-110. S.W. Gong, K. Y. Lam, “Transient response of stiffened composite submersible hull subjected to underwater explosive shock,” Composite Structures 41 (1998), 27-37. James LeBlanc, Arun Shukla, “Dynamic response and damage evolution in composite materials subjected to underwater explosive loading: An experimental and computational study,” Composite Structures (2010), 2421-2430. R.C. Batra, N.M. Hassan, “Response of fiber reinforced composites to underwater explosive loads,” Composites: Part B 38 (2007), 448-468. Rajesh Kalavalapally, Vavi Penmetsa, Ramana Grandhi, “Multidisciplinary optimization of a lightweight torpedo structure subjected to an underwater explosion,” Finite Elements in Analysis and Design 43 (2006), 103-111. Li Jun, Hua Hongxing, “Transient vibrations of laminated composite cylindrical shells exposed to underwater shock waves,” Engineering Structures 31, (2009), 738-748. K. Y. Lam, Z. Zong, Q. X. Wang, “Dynamic response of a laminated pipeline on the seabed subjected to underwater shock,” Composites: Part B 34 (2003), 59-66. ABAQUS Analysis Version 6.8 EF1 User’s Manual. C. S. Smith, “Design of submersible pressure hulls in composite materials,” Marine Structures 4 (1991), 141-182. Cho-Chung Liang, Hung-Wen Chen, Chan-Yung Jen, “Optimum design of filament-wound multilayer-sandwich submersible pressure hulls,” Ocean Engineering 30 (2003), 1941-1967.

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