Naval Engineers Journal最新文献

The FY11 Report to Congress on Annual Long-Range Plan for Construction of Naval Vessels (commonly known as the 30-Year Shipbuilding Plan) forecasts that the Navy's Attack Submarine (SSN) force structure will fall below the requirement of 48 SSNs in 2024, and will remain below the requirement throughout at least 2040 (the limit of the current report). Operating the fleet with fewer ships than necessary to meet commitments around the globe makes it imperative to maximize the mission time provided by each platform. Accordingly, the VIRGINIA Class Submarine Program Office (PMS 450) has developed a plan to mitigate this shortfall in force structure by designing reductions in depot-level maintenance, thereby improving operational availability and maximizing mission time. This plan is encompassed in the Program Office's Reduction of Total Ownership Cost (RTOC) goals. However, actions arising from pressure to reduce Total Ownership Cost (TOC) may have the potential to inadvertently limit available platform mission time if the full consequences, including indirect impacts, are not rigorously assessed and analyzed in advance. The VIRGINIA Class Submarine Program faced this challenge explicitly in implementing the RTOC program while simultaneously working through details of a class maintenance plan modification for later submarines that adds a deployment to the operating cycle. Reducing TOC, while making changes to both the maintenance plan and the platform design, requires an integrated analytic capability to assess the impact of potential changes to both cost and delivered mission time. Evaluating the impact of maintenance changes on mission time is complicated by interactions between multiple stakeholders involved in controlling and managing the lifecycle of the submarine—including those responsible for maintenance planning (and the ability of the maintenance facilities to execute the work), operations and training, and modernizations. An approach and analytic framework, which captures “TOC Effectiveness” (defined as Mission Time Delivered divided by Net Cost) is needed to balance divergent program and stakeholder goals. To capture TOC effectiveness, a time-phased dynamic simulation of the lifecycle employment of VIRGINIA Class Submarines (including depot maintenance time) has been developed to determine the likely submarine employment consequences of the plans, policies, and constraints of the stakeholders involved, and to ensure that the lifecycle maintenance plan targets are achieved. The simulation was validated against historical performance of LOS ANGELES Class maintenance execution at public shipyards, explicitly adjusting for known differences in VIRGINIA Class work packages (the first VIRGINIA Class depot maintenance availability did not start until October 2010). Simulation analysis has identified likely results of alternative plans and/or policies and provided insight into where changes can be made across multiple stakeholders to efficientl

As modular weapon systems allow cost-effective upgrades of a vessel's war-fighting capability, the degradation of the difficult-to-upgrade structure of the vessel may soon become one of the key drivers of vessel retirement and lifecycle maintenance costing. Existing structural design approaches are reviewed, along with recent developments in this field. It is argued that recent research has produced a number of ad hoc metrics for structural design, such as producability; however, to truly address the needs of future ship design teams it is necessary to integrate several such metrics in a systems-engineering view to evaluate how the structural system contributes to the overall capabilities and costs of a proposed vessel. Potential architectures for this approach are discussed, along with key shortcomings. A comparative example is given for structural fatigue of a strength deck under global bending loading, comparing the traditional design approach with a systems-oriented view.

The United States and Allied Maritime domain dominance of sea approaches, lengthy coastlines, and associated rivers and ports is essential. At risk are the security and the economies of the United States and allied countries. The classical Mahan strategies for control of the maritime domain are the role of ships of the line, submarines, and aircraft in roles for Sea and Choke Points Control and Amphibious Assault. Current threats have proven the need to extend tactical response options beyond the ship's hull to its boats and RHIBs used for security and “combatant” craft roles including antipiracy, antidrug, illegal trade, and border security. The stakes are high for these “outside the hull” craft operations because the threats beyond the ship's hull are increasingly more capable and violent and the legal stakes are frequently international in nature. Positive control of these boats is also required for safety-at-sea in darkness and rough sea states. Under these conditions command and control (C2) functions similar to the capabilities of ships of the line are now required to be extended to the ship's manned craft in a distributed defensive and offensive role outside the hull of the ship. The ASNE topics list suggested “Engineering the Fighter Integer … into a Distributed Defense Architecture.” This paper will address the potential threat scenarios, the associated C2 requirements for success, and postulate C2 solutions as available to the United States and allied navies for distributed defensive and offensive architectures for the manned boats beyond the hull of the ship: we call this, “C2 to the Tactical Edge.”

Ship design is a highly intensive and complex process mainly due to the large number of components and competing requirements. With advancement in technology, design, and evaluation processes, more emphasis has been placed on obtaining not just a feasible design, but also an optimal one. Advanced design methods such as set-based design (SBD) can provide a structured approach to evaluating the design space in order to make accurate and informed decisions toward a more globally optimal design. This paper presents the general application of the SBD process for US Naval vessels as well as a specialized focus on changes in design requirements. Specifically, the two main objectives are an evaluation of how delaying decisions using SBD could cause higher adaptability to changes later in the design process and development of a tradeoff space for evaluating reduced sets. A design experiment that simulated cycles of the SBD process was developed and implemented to provide insight into this objective. The different stages of the experiment included determining intersections between design components in the design space, narrowing variable sets to eliminate infeasible regions, and evaluating the effects of changing design requirements.

The Ship to Shore Connector (SSC), a replacement for the Landing Craft, Air Cushion (LCAC), is the first government-led design of a ship in over 15 years. This paper will discuss the changes that a government-led design presents to the design approach, including schedule, organization structure, and design methodology. While presenting challenges, a government-led design also afforded the opportunity to implement a new technique for assessing various systems and ship alternatives, set-based design (SBD). The necessity for implementing SBD was the desire to design SSC from a blank sheet of paper and the need for a replacement craft in a short time frame. That is, the LCACs need to be replaced and consequently the preliminary design phase of the SSC program will only be 12 months. This paper will describe SBD and how it was applied to the SSC, the challenges that the program faced, and an assessment of the new methodology, along with recommendations that future design programs should consider when adopting this approach.

The American Society of Naval Engineers and Society of Naval Architects and Marine Engineers SD-8 Navy Ships Panel, SD-4 Arrangements Panel, and SD-10 Hull Panel, co-sponsored a workshop at the Johns Hopkins University Applied Physics Laboratory on March 30-31, 2011 to explore three challenging and timely issues facing the Navy acquisition and operations organizations.Working Group One was led by RADM Bill Wyatt (Ret), RADM Bob Traister (Ret), Captain Barry Tibbitts (Ret), and Captain Brian Perkinson (Ret). The objective of this working group was to identify what actions can be taken to control the life-cycle costs (LCC) of surface ships. Dr. Norbert Doerry, Technical Director Technology Group, Naval Sea Systems Command, led Working Group Two. The objective of this working group was to develop a list of potential obstacles in the design, acquisition, construction, testing, and in-service support of a surface ship that has strong decoupling of the combat systems from the host ship “truck.” Jason Thomas, chair of the SD-10 hull form panel, led Working Group Three. The objective of this working group was to explore improvements for conveying the design across the contractual boundary and discuss the flexibility left for the shipbuilder during detail design. This paper summarizes the collective thoughts and recommendations of various participants of this workshop with an emphasis on the LCC issue.