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At least 55 records · Page 3

A Government/Industry Summary of the Design Analysis Methods for Vibrations (DAMVIBS) Program

The NASA Langley Research Center in 1984 initiated a rotorcraft structural dynamics program, designated DAMVIBS (Design Analysis Methods for VIBrationS), with the objective of establishing the technology base needed by the rotorcraft industry for developing an advanced finite-element-based dynamics design analysis capability for vibrations. An assessment of the program showed that the DAMVIBS Program has resulted in notable technical achievements and major changes in industrial design practice, all of which have significantly advanced the industry's capability to use and rely on finite-element-based dynamics analyses during the design process.

Kvaternik, Raymond G.↗

Design, Analysis, and Operations Toolkit (DAO-Tk)

The Design, Analysis, and Operations Toolkit (DAO-Tk) is a software package that allows users to explore design optimization, operations decision, and performance characterization of concentrating solar power tower plants. Users interface with the tool through a scripting language, and results are reported in time series tables, plots, runtime logs, and design outputs. Users choose from a list of variables such as tower height, solar multiple, design-point irradiance, thermal storage size, etc., and specify information about the system using a list of parameters. The software can then optimize the specified variables to reduce the cost of energy produced by the system while meeting certain production requirements, accounting for uncertain weather and electricity price forecasts, and correcting for equipment failures or repair time. The DAO-Tk software is the first comprehensive design tool of it's kind to incorporate all of these aspects while being deployed as open source.

Martinek, Janna↗

The NASA/industry design analysis methods for vibrations (DAMVIBS) program: Accomplishments and contributions

A NASA Langley-sponsored rotorcraft structural dynamics program, known as Design Analysis Methods for VIBrationS (DAMVIBS), has been under development since 1984. The objective of this program was to establish the technology base needed by the industry to develop an advanced finite-element-based dynamics design analysis capability for vibrations. Under the program, teams from the four major helicopter manufacturers have formed finite-element models, conducted ground vibration tests, made test/analysis comparisons of both metal and composite airframes, performed 'difficult components' studies on airframes to identify components which need more complete finite-element representation for improved correlation, and evaluated industry codes for computing coupled rotor-airframe vibrations. Studies aimed at establishing the role that structural optimization can play in airframe vibrations design work have also been initiated. Five government/industry meetings were held in connection with these activities during the course of the program. Because the DAMVIBS Program is coming to an end, the fifth meeting included a brief assessment of the program and its benefits to the industry.

Kvaternik, Raymond G.↗

The NASA/industry design analysis methods for vibrations (DAMVIBS) program - Accomplishments and contributions

A NASA Langley-sponsored rotorcraft structural dynamics program, known as Design Analysis Methods for VIBrationS (DAMVIBS), has been under development since 1984. The objective of this program was to establish the technology base needed by the industry to develop an advanced finite-element-based dynamics design analysis capability for vibrations. Under the program, teams from the four major helicopter manufacturers have formed finite-element models, conducted ground vibration tests, made test/analysis comparisons of both metal and composite airframes, performed 'difficult components' studies on airframes to identify components which need more complete finite-element representation for improved correlation, and evaluated industry codes for computing coupled rotor-airframe vibrations. Studies aimed at establishing the role that structural optimization can play in airframe vibrations design work have also been initiated. Five government/industry meetings were held in connection with these activities during the course of the program. Because the DAMVIBS Program is coming to an end, the fifth meeting included a brief assessment of the program and its benefits to the industry.

Kvaternik, Raymond G.↗

Thermal design analysis of shuttle cargo bay payloads

The thermal design analysis methodology, the thermal control philosophy, and preliminary thermal analysis results associated with specific shuttle payloads are presented. The payloads considered are the Get-Away Special canisters being developed by NASA Goddard, which may be flown on a variety of missions, and the six experiments which are mounted on the GSFC pallet to be flown on Operational Flight test No. 4 (OFT-4). The thermal control alternatives currently available to OFT-4 instruments are the use of pallet cold plates (if available) or operational constraints which allow passive thermal control without the use of excessive heater power. The characteristics of a completely passive thermal control design are evidenced by the results of the Get-Away Special canister analysis.

Bartoszek, J. T.↗

The NASA/Industry Design Analysis Methods for Vibrations (DAMVIBS) Program - A government overview

An overview is presented of government contributions to the program called Design Analysis Methods for Vibrations (DAMV) which attempted to develop finite-element-based analyses of rotorcraft vibrations. NASA initiated the program with a finite-element modeling program for the CH-47D tandem-rotor helicopter. The DAMV program emphasized four areas including: airframe finite-element modeling, difficult components studies, coupled rotor-airframe vibrations, and airframe structural optimization. Key accomplishments of the program include industrywide standards for modeling metal and composite airframes, improved industrial designs for vibrations, and the identification of critical structural contributors to airframe vibratory responses. The program also demonstrated the value of incorporating secondary modeling details to improving correlation, and the findings provide the basis for an improved finite-element-based dynamics design-analysis capability.

Kvaternik, Raymond G.↗

Systems design analysis applied to launch vehicle configuration

As emphasis shifts from optimum-performance aerospace systems to least lift-cycle costs, systems designs must seek, adapt, and innovate cost improvement techniques in design through operations. The systems design process of concept, definition, and design was assessed for the types and flow of total quality management techniques that may be applicable in a launch vehicle systems design analysis. Techniques discussed are task ordering, quality leverage, concurrent engineering, Pareto's principle, robustness, quality function deployment, criteria, and others. These cost oriented techniques are as applicable to aerospace systems design analysis as to any large commercial system.

Ryan, R.↗

A compact MOST model for design analysis.

A generalized extension of Kotani's (1970) design analysis model is described that is accurate for a majority of modern MOST structures. The generalized model retains much of the ease of parameter measurement characteristics of the original and enough physical correspondence to accurately represent important steady-state environmental effects, such as those caused by radiation.

Kalinowski, J. J.↗

Managing Uncertainty in Preliminary Aeroshell Design Analysis

An analysis tool to aid in preliminary design of re-entry aeroshells for interplanetary exploration is presented. The computational tool addresses a common feature of design analysis, the need to make use of results from several analysis regimes and from several sources.

Design Methods and Models Design Representations C↗

Design analysis for a nutating plate drive 4

A simplified design analysis was conducted on a nutating plate type drive system for a 2500 horsepower helicopter main rotor gear box. A drive system that split the output torque evenly between two nutating plates for the purpose of reducing the load on each nutating plate was analyzed. Needle bearings were used on the nutating plate pins. The results of the analysis indicate that the required load capacity of the pin bearings and the speed of the nutating plate bearings were beyond the state-of-the-art capacity of rolling-element bearings. The analysis further indicates that the nutating plate drive is less efficient, and results in a higher weight per horsepower than a conventional planetary helicopter transmission with similar design specifications.

Loewenthal, S. H.↗

The design, analysis and application of a practical vibrational platform

The design, analysis and application of a unique vibrational platform employing flexural pivots is described. A Lagrangian equation for the slightly-damped second-order system was derived and verified experimentally. Platform frequencies from 0.7 to 20 Hz with an extremely low damping coefficient were observed. Various educational and instrumentation applications of this simple mechanical system are included.

Tcheng, P.↗

Altair Lander Life Support: Design Analysis Cycles 4 and 5

Life support systems are a critical part of human exploration beyond low earth orbit. NASA s Altair Lunar Lander team is pursuing efficient solutions to the technical challenges of human spaceflight. Life support design efforts up through Design Analysis Cycle (DAC) 4 focused on finding lightweight and reliable solutions for the Sortie and Outpost missions within the Constellation Program. In DAC-4 and later follow on work, changes were made to add functionality for new requirements accepted by the Altair project, and to update the design as knowledge about certain issues or hardware matured. In DAC-5, the Altair project began to consider mission architectures outside the Constellation baseline. Selecting the optimal life support system design is very sensitive to mission duration. When the mission goals and architecture change several trade studies must be conducted to determine the appropriate design. Finally, several areas of work developed through the Altair project may be applicable to other vehicle concepts for microgravity missions. Maturing the Altair life support system related analysis, design, and requirements can provide important information for developers of a wide range of other human vehicles.

Anderson, Molly↗

Altair Lander Life Support: Design Analysis Cycles 4 and 5

Life support systems are a critical part of human exploration beyond low earth orbit. NASA s Altair Lunar Lander team is pursuing efficient solutions to the technical challenges of human spaceflight. Life support design efforts up through Design Analysis Cycle (DAC) 4 focused on finding lightweight and reliable solutions for the Sortie and Outpost missions within the Constellation Program. In DAC-4 and later follow on work, changes were made to add functionality for new requirements accepted by the Altair project, and to update the design as knowledge about certain issues or hardware matured. In DAC-5, the Altair project began to consider mission architectures outside the Constellation baseline. Selecting the optimal life support system design is very sensitive to mission duration. When the mission goals and architecture change several trade studies must be conducted to determine the appropriate design. Finally, several areas of work developed through the Altair project may be applicable to other vehicle concepts for microgravity missions. Maturing the Altair life support system related analysis, design, and requirements can provide important information for developers of a wide range of other human vehicles.

Anderson, Molly↗

The design analysis of a rechargeable lithium cell for space applications

Ambient temperature rechargeable lithium batteries are needed by NASA for advanced space power applications for future missions. Specific energies of not less than 100 Wh/kg and long cycle life are critical performance goals. A design analysis of a 35 Ah Li-TiS2 cell was carried out using literature and experimental data to identify key design parameters governing specific energy. It is found that high specific energies are achievable in prismatic cells, especially with the use of advanced hardware materials. There is a serious need for a greatly expanded engineering database in order to enable more quantitative design analysis.

Subba Rao, S.↗

Design, analysis, and fabrication of the technology integration box beam

Numerous design concepts, materials, and manufacturing methods were investigated analytically and empirically for the covers and spars of a transport wing box. This information was applied to the design, analysis, and fabrication of a full-scale section of a transport wing box. A blade-stiffened design was selected for the upper and lower covers of the box. These covers have been constructed using three styles of AS4/974 prepreg fabrics. The front and rear T-stiffened channel spars were filament wound using AS4/1806 towpreg. Covers, ribs, and spars were assembled using mechanical fasteners. When they are completed later this year, the tests on the technology integration box beam will demonstrate the structural integrity of an advanced composite wing design which is 25 percent lighter than the metal baseline.

Griffin, C. F.↗

Framework for Multidisciplinary Analysis, Design, and Optimization with High-Fidelity Analysis Tools

A plan is presented for the development of a high fidelity multidisciplinary optimization process for rotorcraft. The plan formulates individual disciplinary design problems, identifies practical high-fidelity tools and processes that can be incorporated in an automated optimization environment, and establishes statements of the multidisciplinary design problem including objectives, constraints, design variables, and cross-disciplinary dependencies. Five key disciplinary areas are selected in the development plan. These are rotor aerodynamics, rotor structures and dynamics, fuselage aerodynamics, fuselage structures, and propulsion / drive system. Flying qualities and noise are included as ancillary areas. Consistency across engineering disciplines is maintained with a central geometry engine that supports all multidisciplinary analysis. The multidisciplinary optimization process targets the preliminary design cycle where gross elements of the helicopter have been defined. These might include number of rotors and rotor configuration (tandem, coaxial, etc.). It is at this stage that sufficient configuration information is defined to perform high-fidelity analysis. At the same time there is enough design freedom to influence a design. The rotorcraft multidisciplinary optimization tool is built and substantiated throughout its development cycle in a staged approach by incorporating disciplines sequentially.

Orr, Stanley A.↗

Advanced hydrogen/oxygen thrust chamber design analysis

The results are reported of the advanced hydrogen/oxygen thrust chamber design analysis program. The primary objectives of this program were to: (1) provide an in-depth analytical investigation to develop thrust chamber cooling and fatigue life limitations of an advanced, high pressure, high performance H2/O2 engine design of 20,000-pounds (88960.0 N) thrust; and (2) integrate the existing heat transfer analysis, thermal fatigue and stress aspects for advanced chambers into a comprehensive computer program. Thrust chamber designs and analyses were performed to evaluate various combustor materials, coolant passage configurations (tubes and channels), and cooling circuits to define the nominal 1900 psia (1.31 x 10 to the 7th power N/sq m) chamber pressure, 300-cycle life thrust chamber. The cycle life capability of the selected configuration was then determined for three duty cycles. Also the influence of cycle life and chamber pressure on thrust chamber design was investigated by varying in cycle life requirements at the nominal chamber pressure and by varying the chamber pressure at the nominal cycle life requirement.

Shoji, J. M.↗