SBIR-STTR Award

In modern submarine design, the effort to produce more efficient, lighter and less expensive structures drives the analysis beyond simple historic empirical techniques towards a higher reliance on finite element modeling (FEM) analysis. The problem increases in complexity with the choice of FEM modeling techniques varying widely between different organizations in their choice of criteria such as element formulation, mesh density, assumptions, and boundary conditions. To solve this problem MTech will develop a Finite Element Manual to be used by NAVSEA and the Shipyards as a design tool to ensure FEM techniques are consistent and appropriate for the design detail. MTech will combine conventional techniques with innovative solutions to reduce US Navy cost and schedule. The MTech design tool will ensure equivalent tools are used, document common knowledge of best practices, provide accurate guidance and provide test verified techniques all while providing the analyst maximum flexibility.

Benefit:
In an environment of reduced funding and additional oversight, design uncertainty decreases and delays the availability of the US Navys submarine fleet. The engineering effort associated with the execution of these calculations and development of the associated deliverable reports forms a significant portion of the overall Non Recurring Engineering (NRE) budget for a submarine program. To limit these costs, the development of a design manual of FEM procedures based on bridging the gap between the current design process and one with specific verified techniques is needed.

Keywords:
Verification Testing, Verification Testing, complex geometry, Standard Techniques for Finite Element Modeling of Complex Structures, Stress Concentrations, Finite element modeling, FEM Guidelines and Procedures, Submarine Hull Structure, Structural Analysis

Phase II Full Proposal for SBIR contract for topic: N171-059 Verification and Optimization of Advanced Finite Element Modeling Techniques for Complex Submarine Hull Structures . This NAVSEA Phase II SBIR proposal describes the technical objectives and work plan toward the creation of a manual of finite element modeling(FEM) procedures for complex submarine hull structures, with accuracy validated through analysis and testing. The proposed approach builds on the feasibility efforts of Phase I using FEM analysis, test validation, sensitivity studies, index problems and industry best practices . The analysis tasks identify FEM modeling criteria limitations specific to complex submarine geometry and provide guidance to insure correct interpretation of analysis results. Test validation plans are identified, including reduced-scale risk mitigation testing within Phase II. The proposed objective and work plan show a path toward development of a FEM manual for complex submarine hull structures, which will avoid cost and schedule overruns caused by analysis method conflicts between the DON technical community and submarine design yards. The resulting manual can be extended for commercial use to the shipbuilding, oil exploration and other industries.

Benefit:
The Navy has shown as interest in determining technologies and methods that streamline the undersea weapon system design process. A large portion of the development cycle of submarine hull structures relates to detailed analysis of complex geometry details. With the lack of a verified method, conflicts over chosen methods between the shipyards and the NAVSEA technical community has led to additional analysis, schedule delays and cost over-runs. A project goal is to allow those programs to accelerate their design capability. The future OHIO Class submarine would be a target platform to benefit from this additional capability. However, other PEO Submarines groups would find immediate applications for this technology. These groups include PMS450-VIRGINIA and PMS397-COLUMBIA Class program offices of record and PMS392-Fleet Support. The tool being developed will have immediate usage for surface vessels and commercial submersibles. The overall tool architecture will be readily adaptable to aerospace, automotive, nautical and any other industry performing large scale idealization of complex structures. We know from our experience that a design tool with this information is not commercially available in the aerospace industry and would find great interest from commercial organizations. Uses in aircraft Type Certification, Modifications and Repairs and Supplemental Type Certificates (STCs) would increase FAA confidence while reducing development cost. However, advanced structural analysis transcends multiple industries with increasing geometrically complex items being developed using cutting-edge CAD and FEM analysis tools. The ability of designers to rapidly create complex designs puts increased demands on structural analysts to substantiate designs using FEM analysis. Unfortunately, FEA software will allow untrained analysts to produce results that look good on the surface but are inaccurate. This leads to faulty designs entering the marketplace placing companies at risk for injury, litigation and reduced customer satisfaction. Utilizing a tool such as ours would allow companies to standardize their techniques and reduce cost, schedule and risk. By standardizing the processes and creating best of breed procedures for Finite Element Analysis, our tool reduces uncertainty, increases confidence, and extends the life of a multitude of products. Furthermore, the unique process of developing this technology will provide MTech with a competitive edge in securing future design and analysis contracts. The deep understanding of the applications of this research and design methodologies will place MTech as a subject matter expert in this highly specialized field.

Keywords:
Bulkhead Taper Insert, complex geometry, Submarine Hull Structure, Stress Analysis, Model verification, Finite element modeling, Penetration Insert, Ring-Stiffened Pressure Vessel