DockShock: Predicting Target Response
Dr. Russel Miller, Anteon Corporation

Abstract:
The DockShock Research and Development Program was initiated by the Office of Naval Research (ONR) to develop an environmentally acceptable and less costly alternative for conducting full ship shock tests compared to the current open ocean testing using large explosive charges.  The DockShock system, currently being developed by Anteon and its team, uses an array of electrochemical or electromechanical sources to generate a shock pulse and simulate the at-sea ship target response within a dockside setting.  A bubble screen is employed to mitigate the pressure pulse to sufficiently low levels so that the surrounding structures and environment are protected.  The objective of the R&D technical program is to demonstrate by analyses, design and testing that DockShock provides the desired ship target response and that the environment is not adversely impacted. At the basis of the DockShock system is an array of sources with high pressure pulse generation capability.  The sources are submerged in close proximity to the ship or desired target.  The number of sources, source energy, source size and spacing is engineered based on the required pressure pulse impinging upon the ship. Computational modeling has been conducted to simulate the target response generated by an array of electrochemical/electromechanical sources.  Several steps are required in the target response analysis.  First, BAE Systems, a team partner with Anteon in the DockShock program, creates source models covering a wide range of peak pressures and impulse strengths. Second, models of the BAE sources are then implemented by Anteon using the DYSMAS fluid-structure modeling and simulation tool.  DYSMAS combines an Euler fluid model called Gemini with a lagrangian structural model DYNA_N.  Third, the individual source models are combined into arrays and submerged underwater next to FSP and ship section targets.  The computational models simulate the source activation, the pressure pulse propagation, and the target excitation and response.  The deformations, velocities, and accelerations of the target are monitored throughout the simulation. Fourth, pressures in the water and target response are then compared to experimental and computational time histories resulting from explosives.  Finally, modifications are made, as necessary, to the sources and array geometry to improve the comparisons between experiment and computation.

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