OPERATIONAL ANALYSIS IN SYSTEM DESIGN OF SUBMARINES DURING THE EARLY PHASES

This paper presents a new method for operational analysis (OA) as a tool in simulation based design (SBD) for Naval Integrated Complex Systems (NICS), here applied to the submarine domain. An operational analysis model is developed and described. The first step of the design process is to identify and collect the needs from the customer and stakeholders, from which requirements can be deduced and designed in an organized way, i.e. requirement elucidation. It is important to evaluate the benefits or penalties of each requirement on the design as early as possible during initial design. Thus the OA-model must be able to evaluate requirements aggregated in synthesised ships such as initial concepts, i.e. Play-Cards, as representations of a submarine concept in the functions domain where the first set of requirements are designed, and establish their Measure of Capability (MoC) and Measure of Effectiveness (MoE). The work has resulted in an OA-model for submarine design that can be used during the development and for evaluation during the life cycle of a submarine system. The purpose of integrating OA in the design process is to explore the design space and evaluate not only technical solutions and cost but also the system effect in the early phases and thereby find and describe a suitable design room. This will generate a more rapid knowledge growth compared to the classic basic ship design procedures which focus on technical performance and cost. It is expected that we not only reach a higher level of knowledge about the design object but also achieve higher precision in the compliance to needs and deduced and designed requirements by the use of an OA-model as an integrated tool during initial design. This approach also invites customer participation within the framework of integrated project teams.

On geometry parameterization for simulation-driven design closure of antenna structures

Full-wave electromagnetic (EM) simulation tools have become ubiquitous in antenna design, especially final tuning of geometry parameters. From the reliability standpoint, the recommended realization of EM-driven design is through rigorous numerical optimization. It is a challenging endeavor with the major issues related to the high computational cost of the process, but also the necessity of handling several objectives and constraints over often highly-dimensional parameter spaces. From the numerical perspective, making decisions about the formulation of the optimization problem, the approach to handling the design constraints, but also parameterization of the antenna geometry, are all non-trivial. At the same time, these issues are interleaved, and may play an important role in the performance and reliability of the simulation-based design closure process. This paper demonstrates that the approach to arranging the structure parameterization (e.g., the use of absolute or relative parameters) may have a major effect of the optimization outcome. Our investigations are carried out using three broadband monopole antennas optimized under different scenarios and using different parameterizations. In particular, the results indicate that relative parameterization is preferred for optimization of input characteristics, whereas absolute parameterization is more suitable for size reduction.

FE-Simulation Based Design of Wear-Optimized Cutting Edge Roundings

The performance of cutting tools can be significantly enhanced by matching the cutting edge rounding to the process and material properties. However, the conventional cutting edge rounding design is characterized by a significant number of experimental machining studies, which involve considerable cost, time, and resources. In this study, a novel approach to cutting edge rounding design using FEM-based chip formation simulations is presented. Based on a parameterized simulation model, tool temperatures, stresses and relative velocities can be calculated as a function of tool microgeometry. It can be shown that the external tool loads can be simulated with high agreement. With the help of these loads and the use of wear models, the resulting tool wear and the optimum cutting edge rounding can be determined. The final experimental investigations show a qualitatively high agreement to the simulation, which will enable a reduced effort design of the cutting edge in the future.

On geometry parameterization for simulation-driven design closure of antenna structures

Full-wave electromagnetic (EM) simulation tools have become ubiquitous in antenna design, especially final tuning of geometry parameters. From the reliability standpoint, the recommended realization of EM-driven design is through rigorous numerical optimization. It is a challenging endeavor with the major issues related to the high computational cost of the process, but also the necessity of handling several objectives and constraints over often highly-dimensional parameter spaces. From the numerical perspective, making decisions about the formulation of the optimization problem, the approach to handling the design constraints, but also parameterization of the antenna geometry, are all non-trivial. At the same time, these issues are interleaved, and may play an important role in the performance and reliability of the simulation-based design closure process. This paper demonstrates that the approach to arranging the structure parameterization (e.g., the use of absolute or relative parameters) may have a major effect of the optimization outcome. Our investigations are carried out using three broadband monopole antennas optimized under different scenarios and using different parameterizations. In particular, the results indicate that relative parameterization is preferred for optimization of input characteristics, whereas absolute parameterization is more suitable for size reduction.