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Vlahopoulos N.,University of Michigan | Medyanik S.,Michigan Engineering Services, LLC
SAE Technical Papers | Year: 2015

In the Energy Finite element Analysis (EFEA) method, the governing differential equations are formulated for an energy variable that has been spatially averaged over a wavelength and time averaged over a period. A finite element approach is used for solving the differential equations numerically. Therefore, a library of elements is necessary for modeling the various wave bearing domains that are present in a structural-acoustic system. Discontinuities between wave bearing domains always exist due to the geometry, from a change in material properties, from multiple components being connected together, or from different media interfacing with each other. Therefore, a library of joints is also necessary for modeling the various types of physical connections which can be encountered in a structural-acoustic system. In this paper, a new joint formulation is presented for using incompatible meshes in EFEA models, when shapes and/or sizes of elements at structural-acoustic interfaces do not match. The algorithm which identifies automatically the joints in a finite element model is presented, and the implementation of the joints in the EFEA solver is discussed. The new developments are tested by comparing results generated using incompatible models for a simple configuration, and through comparison to test data for a representative automotive air-borne noise application. Copyright © 2015 SAE International.


Grant
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 99.48K | Year: 2009

One of the main attributes contributing to the civil competitiveness of rotorcraft, is the continuously increasing expectations for passenger comfort which is directly related with reduced vibration levels and reduced interior noise levels. Such expectations are amplified in the VIP market where people are used in the acoustic and vibration levels of civil and executive jets. One of the most critical excitations for interior noise in helicopters is the one from the gearbox. Thus, the structure-borne noise path (i.e. excitation propagating from mounting locations through the fuselage structure to the panels of the cabin and to the interior) must be captured in rotorcraft interior noise computations. This proposal addresses the need stated in the solicitation for developing physics based tools that can be used within a multi-disciplinary design-analysis-optimization for computing interior noise in rotorcraft applications. The hybrid FEA method can be used for structure-borne helicopter applications and can be integrated very easily (due to the finite element based model) with models from other disciplines within a multidisciplinary design environment. During the Phase I project the main focus will be in demonstrating the feasibility of the hybrid FEA technology for computing rotorcraft structure-borne interior noise from gearbox excitation. A multi-discipline optimization rotorcraft case study will also be performed for demonstrating how the hybrid FEA facilitates the design of a rotorcraft fuselage based on simultaneous crash landing/passenger safety and structure-borne noise considerations. The new developments will become part of MES' commercial EFEA code and of its implementation within SOL400 of NASTRAN. UTRC will participate in the proposed effort for ensuring relevance of the work to rotorcraft interests and for providing technical consultancy.


Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase I | Award Amount: 149.90K | Year: 2015

ABSTRACT:Advancements in propulsion systems, aerodynamics, and flight control capabilities are enabling hypersonic vehicles to operate at high speeds and altitudes. Therefore, significant new demands are placed on the materials used for constructing a hypersonic system due to the harsh environment created by the high speeds. An integrated design approach that considers the design, the processing, and the selection of the materials simultaneously with the overall design of the vehicle will link the material properties selection to the overall performance of a hypersonic vehicle and constitute a major new enabling technology. In this project the ICMSE modeling and simulation approaches will be investigated and the material selection will be integrated with the decision support environment which is offered by the DS Toolkit. The DS Toolkit offers the ability to determine how the performance metrics and the operational requirements change when the design of the vehicle varies. The DS Toolkit has been employed in the past for hypersonic vehicle design. The new developments will be employed for conducting the material selection, the trajectory analysis, and the thermal protection system (TPS) design simultaneously for a hypersonic vehicle. Thus, the tight integration of the material selection with the overall design process will be demonstrated.BENEFIT:Integrating material selection with product design is of interest to the shipbuilding, automotive, aircraft, space, military ground vehicle, and energy Industry sectors. The common factors among these Industries are: all use multi-physics simulation models for assessing the performance of their products during design; designing materials for cost effectiveness, ease of manufacturing, and enhanced properties is an essential part in new product development; they all have needs for reducing weight and creating fuel efficient systems; they all have multiple and mutual competing performance requirements. In addition, the energy Industry and any powertrain application have similar needs with hypersonic vehicles for materials that exhibit good mechanical properties at high temperatures. Thus, significant benefits will be offered in many Industries by the technology which will be developed by the proposed project.


Grant
Agency: Department of Defense | Branch: Army | Program: SBIR | Phase: Phase I | Award Amount: 149.98K | Year: 2013

Design is the act of generating information that is used to make decisions or produce a product. Modern products are moving away from segregated disjointed systems and towards interdependent systems that utilize shared hardware and software resources (e.g. zonal power distribution, ethernet based controls, shared racks and mounts to facilitate advanced outfitting, etc.). Determining the appropriate balance between hardware and software configurations is an integral part of the design process. Modern design methods and tools still create and analyze designs as a set of disjointed systems, or in most cases, segregated analysis operations are organized by traditional technical domains. The concept of"shared resource"must become part of an integrated design process that considers allocation trade-off between hardware and software capabilities. Developing a software tool for balancing decisions when allocating investments in hardware and software during the development of complex DoD systems will have an impact on the lifecycle cost, the reliability, the robustness, and the utility of a new Defense system. Such a software tool will have the ability to select in an automated top-down approach the hardware/software configuration which will maximize the utility of the system through probabilistic analysis given a set of targeted performance characteristics. It will also be possible to use the new software in a manual bottom-up approach in order to assess the utility of a particular selection of hardware/software configuration made by the user. In either mode of operation, information will be presented in a graphical format for easy interpretation of the impacts that the selections have to the performance of the system. Such a research effort will be pursued by Michigan Engineering Services, LLC (MES) under the proposed SBIR program for developing a Decision Support toolkit for Hardware/Software allocation studies (DS toolkit for H/S).


Grant
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 99.49K | Year: 2011

The design of an aircraft is a highly iterative process. During the conceptual design phase there is no time for developing detailed simulation models and decisions are typically made either by using low fidelity models or existing data and regression models. However, the decisions made during the conceptual design phase greatly affect the performance of the aircraft and the associated cost, and typically the majority of the cost is locked during very early stages of the design process. Usually the sound insulation requirements of a passenger cabin are met after the outer mold line of the aircraft and the design of the fuselage structure have been completed and this approach adds weight to the design. Ideally the structural-acoustic concerns should enter the design cycle early and be considered along with other main design disciplines. During the early design stages of an aircraft the interior noise performance of different fuselage configurations must be evaluated based on the following information: length, cross sectional stations as a function of longitudinal location, main interior arrangements, spacing and size of stiffeners and stringers, thickness and material properties of insulation blankets, thickness and material properties of the fuselage and of the trim panels, and the type of acoustic treatment placed in the interior. The acoustic performance expressed in terms of noise reduction comprises the metric for assessing the aircraft performance for interior noise considerations. The proposed project will develop an easy to use, physics based, computational capability that can provide fast an assessment for the interior noise of either conventional or novel aircraft during the early stages of the design process. It will also allow engaging information from multi-scale simulations for designing quiet composite materials with increased damping and reduced radiation efficiency characteristics.


Grant
Agency: Department of Defense | Branch: Office of the Secretary of Defense | Program: SBIR | Phase: Phase II | Award Amount: 999.74K | Year: 2014

In DoD systems a large number of software systems are embedded in a single platform. In the proposed research the ability to determine simultaneously the optimal allocation of resources and the associated configurations for multiple hardware/software systems will be developed in the DS Toolkit. The MDO algorithms of the Toolkit enable the new developments due to their abilities to balance decisions among multiple competing objectives and constraints. New decision algorithms based on set-based design and fuzzy logic will be implemented. The probabilistic computations for robustness and reliability will be strengthened and evidence theory will be used for introducing expert opinion in the probabilistic assessments. Existing capabilities of MES in generating metamodels for scalar and time dependent performance metrics will be integrated in the Toolkit. New visualization capabilities will be developed in support of all new research. Case studies will demonstrate the work. Manuals and the source code will be delivered to the sponsor. The proposed research is aligned with several ERS objectives and will develop a unique tool for hardware/software allocation trades without duplicating existing products. The transition to DoD primes (Newport News Shipbuilding) and to DoD (US Army TARDEC, CREATE) will take place through the current utilization of the DS Toolkit by these organizations.


Grant
Agency: National Aeronautics and Space Administration | Branch: | Program: STTR | Phase: Phase I | Award Amount: 124.86K | Year: 2015

Entry vehicle design and aircraft design are just two examples of systems that are of interest to NASA, requiring interactions and exchange of information among multiple performance disciplines. Since any computational optimization process relies on simulation models for identifying the impact of design changes in meeting performance expectations and improving metrics of goodness, it is essential that the uncertainty quantification of these models is captured by the optimization. Fuzzy Logic (FL) provides a systematic approach for introducing linguistic articulation of mental perception into a mathematical framework. In the proposed project the FL approach will be used for introducing in an automated multidisciplinary optimization process the human judgment and the expert opinion associated with the credibility of the modeling and simulations (as stated in the NASA-STD-7009) which are utilized for making decisions. The proposing firm has developed a Decision Support Toolkit (DS Toolkit) which can be used for multidisciplinary design and for balancing many multiple competing performance objectives. The multidisciplinary analysis is done automatically due to specialized algorithms and capabilities which are embedded in the DS Toolkit; both discrete and continuous design variables can be defined. The proposed research will develop the ability to consider the credibility of the models and of the simulations which are used for evaluating the performance requirements and the performance metrics during the analysis. A Fuzzy Logic System (FLS) capability will be developed for this purpose. The membership functions in the FLS will be reflecting the credibility scores assigned by subject matter experts to each one of the eight credibility factors of a simulation. The rule bank in the FLS will capture the expert opinion of the decision makers on how the credibility of the simulations will influences the decisions which are made by the optimization process.


Grant
Agency: Department of Defense | Branch: Navy | Program: SBIR | Phase: Phase I | Award Amount: 70.00K | Year: 2010

The U.S. Armed forces face the need for rapid deployment from the United States in order to engage regional threats decisively on a global basis. Size and weight are paramount factors for ground combat vehicles supporting this force projection structure. Lighter weight vehicles is an enabling factor for faster transport, higher mobility, fuel conservation, and a reduced ground footprint of supporting forces. At the same time the design of ground combat vehicles to survive a blast from a mine or from an Improvised Explosive Device (IED) is of great interest in order to provide an appropriate level of protection for the vehicle and its occupants. Weight reduction and high levels of survivability are mutually competing objectives. Therefore, a significant effort must be invested in order to ensure that the vehicle’s survivability is not compromised. Michigan Engineering Services, LLC (MES) has developed a Blast Event Simulation sysTem (BEST) for providing a seamless and easy to use technology for conducting blast simulations and injury analysis. In this manner it eliminates the burden of specialized knowledge from the analyst who will be conducting the simulations. The BEST simulation process was first validated through comparison with test data available in the literature. Further validation has been completed for a generic vehicle structure with a V shaped double bottom and subjected to a load from an explosion. A Hybrid III ATDs was placed inside the structure during the test. Results from the BEST simulation process were compared successfully with test data for the deformation of the structure and for the loads developed in the lower legs of the occupant. The proposed Phase I effort will demonstrate the ability of BEST to conduct simulations for non-centerline IED explosions, and the feasibility of utilizing BEST for introducing design changes in the generic vehicle for improving the occupant’s safety.


Grant
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 599.98K | Year: 2010

One of the main attributes contributing to the competitiveness of rotorcraft, is the continuously increasing expectations for passenger comfort which is directly related with reduced vibration levels and reduced interior noise levels. Such expectations are amplified in the VIP market where people are used in the acoustic and vibration levels of civil and executive jets. One of the most critical excitations for interior noise in helicopters is the one from the gearbox. Thus, the structure-borne noise path (i.e. excitation propagating from mounting locations through the fuselage structure to the panels of the cabin and to the interior) must be captured in rotorcraft interior noise computations. This proposal addresses the need stated in the solicitation for developing physics based tools that can be used within a multi-disciplinary design-analysis-optimization for computing interior noise in rotorcraft applications. Currently, there is no robust simulation capability for this type of acoustic simulations. The hybrid FEA method can be used for structure-borne helicopter applications and can be integrated very easily (due to the finite element based model) with models from other disciplines within a multidisciplinary design environment. It combines conventional FEA with Energy Finite Element (EFEA) and it extends the frequency range of applicability of an existing finite element model by converting the elements that model the flexible panels into EFEA type of elements. A seamless Hybrid FEA capability of commercial quality will be developed based on MES' commercial EFEA code. UTRC will participate in the proposed effort for validating the new developments through comparisons to test data for a rotorcraft structure and for providing technical consultancy.


Grant
Agency: National Aeronautics and Space Administration | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 99.61K | Year: 2010

Aircraft design is a complex process requiring interactions and exchange of information among multiple disciplines such as aerodynamics, strength, fatigue, controls, propulsion, corrosion, maintenance, and manufacturing. A lot of attention has been paid during the past fifteen years in the Multi-disciplinary Design Optimization (MDO) nature of the aircraft design process. However, a consistent void in aircraft design is the ability to integrate high-fidelity computational capabilities from multiple disciplines within an organized MDO environment. Integrating high fidelity simulation technology (that has been developed over the years though significant investments) within a MDO environment will constitute a disruptive technological development in aircraft design. The ability to replace time consuming solvers with metamodels within the highly iterative environment of an integrated network of optimizations is critical for engaging high fidelity simulation tools in the MDO analysis of complex aircraft systems. Previous work completed by the proposing firm has demonstrated the feasibility of conducting such MDO analysis for an aircraft system, while considering outer mold line shape optimization and structural sizing simultaneously. Since the ability to create metamodels from results obtained at a number of sample points from the actual solvers is the key enabling factor for conducting the multi-discipline optimization analysis, the proposed project will use as foundation the existing metamodeling capability of the proposing firm and will pursue new research that will lead to the development of a powerful stand-alone commercial product for metamodel development. The latter, along with the proposing firm's MDO solver will provide the means for operating an integrated network of optimizations for designing aircraft systems.

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