Search NASA⌕ Search

SEARCH · Search NASA

Results for “Nastran”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Computer Aided Modeling and Post Processing with NASTRAN Analysis

Computer aided engineering systems are invaluable tools in performing NASTRAN finite element analysis. These techniques are implemented in both the pre-processing and post-processing phases of the NASTRAN analysis. The finite element model development, or pre-processing phase, was automated with a computer aided modeling program called Supertabl, and the review and interpretation of the results of the NASTRAN analysis, or post-processing phase, was automated with a computer aided plotting program called Output Display. An intermediate program, Nasplot, which was developed in-house, has also helped to cut down on the model checkout time and reduce errors in the model. An interface has been established between the finite element computer aided engineering system and the Learjet computer aided design system whereby data can be transferred back and forth between the two. These systems have significantly improved productivity and the ability to perform NASTRAN analysis in response to product development requests.

Boroughs, R. R.↗
NASA NTRS1985

New Enhancements in April 85 NASTRAN Release

Several features were added to COSMIC NASTRAN, along with some enhancements to improve or update existing capabilities. Most of these additions and enhancements were provided by industry users to be incorporated into NASTRAN for wider use. DIAG 48 provides a synopsis of significant developments in past NASTRAN releases (1983-1985) and indexes all diagnostic output messages and operation requests (DOMOR). Other features include: volume and surface computation of the 2-D and 3-D elements, NOLIN5 input and; NASTRAN PLOTOPT-N (where N = 2, 3, 4, or 5); shrink element plots; and output scan. A nonprint option on stress and force output request cards was added. Automated find and nofind options on the plot card, fully stressed design, high level plate elements, eigenvalue messages, and upgrading of all FORTRAN source code to the ANSI standard are enhancements made.

Chan, G. C.↗
NASA NTRS1988

A NASTRAN DMAP alter for linear buckling analysis under dynamic loading

A unique modification to the NASTRAN solution sequence for transient analysis with direct time integration (COSMIC NASTRAN rigid format 9) was developed and incorporated into a DMAP alter. This DMAP alter calculates the buckling stability of a dynamically loaded structure, and is used to predict the onset of structural buckling under stress wave loading conditions. The modified solution sequence incorporates the linear buckling analysis capability (rigid format 5) of NASTRAN into the existing Transient solution rigid format in such a way as to provide a time dependent eigensolution which is used to assess the buckling stability of the structure as it responds to the impulsive load. As a demonstration of the validity of this modified solution procedure, the dynamic buckling of a prismatic bar subjected to an impulsive longitudinal compression is analyzed and compared to the known theoretical solution. In addition, a dynamic buckling analysis is performed for the analytically less tractable problem of the localized dynamic buckling of an initially flawed composite laminate under transverse impact loading. The addition of this DMAP alter to the transient solution sequence in NASTRAN facilitates the prediction of both time and mode of buckling.

Aiello, Robert A.↗
NASA NTRS1989

A NASTRAN DMAP alter for linear buckling analysis under dynamic loading

A modification to the NASTRAN solution sequence for transient analysis with direct time integration (COSMIC NASTRAN rigid format 9) was developed and incorporated into a DMAP alter. This DMAP alter calculates the buckling stability of a dynamically loaded structure, and is used to predict the onset of structural buckling under stress-wave loading conditions. The modified solution sequence incorporates the linear buckling analysis capability (rigid format 5) of NASTRAN into the existing Transient solution rigid format in such a way as to provide a time dependent eigensolution which is used to assess the buckling stability of the structure as it responds to the impulsive load. As a demonstration of the validity of this modified solution procedure, the dynamic buckling of a prismatic bar subjected to an impulsive longitudinal compression is analyzed and compared to the known theoretical solution. In addition, a dynamic buckling analysis is performed for the analytically less tractable problem of the localized dynamic buckling of an initially flawed composite laminate under transverse impact loading. The addition of this DMAP alter to the transient solution sequence in NASTRAN facilitates the computational prediction of both the time at which the onset of dynamic buckling occurs in an impulsively loaded structure, and the dynamic buckling mode shapes of that structure.

Aiello, Robert A.↗
NASA NTRS1991

Online NASTRAN documentation

The distribution of NASTRAN User Manual information has been difficult because of the delay in printing and difficulty in identification of all the users. This has caused many users not to have the current information for the release of NASTRAN that could be available to them. The User Manual updates have been supplied with the NASTRAN Releases, but distribution within organizations was not coordinated with access to releases. The Executive Control, Case Control, and Bulk Data sections are supplied in machine readable format with the 91 Release of NASTRAN. This information is supplied on the release tapes in ASCII format, and a FORTRAN program to access this information is supplied on the release tapes. This will allow each user to have immediate access to User Manual level documentation with the release. The sections on utilities, plotting, and substructures are expected to be prepared for the 92 Release.

Turner, Horace Q.↗
NASA NTRS1971

An Evaluation of Current NASTRAN Discrete Element Models for Monocoque and Semimonocoque Structures

The current discrete element analysis models in NASTRAN, Levels 8. 1.0 and 11. 1. 0, are evaluated for semi-rnonocoque and monocoque structures. Comparative results are presented with the FORMAT-I11 general-purpose code for a swept wing statics analysis and a Skylab substructure vibration analysis. Good agreement between Level i I. 1.0 and FORMAT-111 is demonstrated; however, a major error in Level 8. 1.0 was discovered on the Skylab vibration problem. The computational performance of NASTRAN was superior to FORMAT, but the vibration rigid format was found to have several inefficiencies. Comparative results are also presented between Level 11. 1. 0 and STACUSS, SLADE, BOND, UNIVALVE, and another special-purpose code. Results for two of the structures analyzed, a cylindrical shell and an elliptic plate, indicate curved discrete elements are significantly more accurate than the plate elements in NASTRAN for the same number of degrees of freedom.

Edward L. Stanton↗
NASA NTRS1972

Some applications of NASTRAN to the buckling of thin cylindrical shells with cutouts

The buckling of isotropic and waffle-stiffened circular cylinders with and without cutouts was studied using NASTRAN's Rigid Format 5 for the case of axial compressive loading. The results obtained for the cylinders without cutouts are compared with available reference solutions. The results for the isotropic cylinders containing a single circular cutout with selected radii are compared with available experimental data. For the waffle-stiffened cyclinder, the effect of two diametrically opposed rectangular cutouts was studied. A DMAP alter sequence was used to permit the necessary application of different prebuckling and buckling boundary conditions. Advantage was taken of available symmetry planes to formulate equivalent NASTRAN model segments which reduced the associated computational cost of performing the analyses. Limitations of the applicability of NASTRAN for the solution of problems with nonlinear characteristics are discussed.

Williams, J. G.↗
NASA NTRS1972

Experiences in interfacing NASTRAN with another finite element program

The coupling of NASTRAN to another finite element program developed for the static analysis of automotive structures is discussed. The two programs were coupled together to use the substructuring capability of the in-house program and the normal mode analysis capability of NASTRAN. Modifications were made to the NASTRAN program in order to make the coupling feasible.

Schwerzler, D. D.↗
NASA NTRS1972

Some aspects of the NASTRAN program output

The NASTRAN program output is discussed from a structural analysts point of view, and the simple modifications which were made to the program in order to improve it are also described. The convenience of the output for use in original design work is critically appraised and compared with the output from ASTRAL. It is shown that considerable hand calculation is necessary in order to extract useful load distribution data from the available NASTRAN output. For this reason, some effort was directed toward providing additional force output for the NASTRAN shear panel element.

Gregory, D. J.↗
NASA NTRS1972

The BANDIT computer program for the reduction of matrix bandwidth for NASTRAN

A computer program, BANDIT, is described which was developed for use as a preprocessor to NASTRAN to automatically resequence the grid point numbers for reduced matrix bandwidth. The BANDIT program accepts a standard NASTRAN data deck as input, resequences the grid point numbers for reduced bandwidth, and generates a set of SEQGP cards for insertion into the NASTRAN bulk data deck. BANDIT uses the Cuthill-McKee strategy for resequencing grid points. The program is operational on the CDC 6000 series of computers, the IBM 360, and the Univac 1108.

Everstine, G. C.↗
NASA NTRS1972

Applications of NASTRAN to nuclear problems

The extent to which suitable solutions may be obtained for one physics problem and two engineering type problems is traced. NASTRAN appears to be a practical tool to solve one-group steady-state neutron diffusion equations. Transient diffusion analysis may be performed after new levels that allow time-dependent temperature calculations are developed. NASTRAN piecewise linear anlaysis may be applied to solve those plasticity problems for which a smooth stress-strain curve can be used to describe the nonlinear material behavior. The accuracy decreases when sharp transitions in the stress-strain relations are involved. Improved NASTRAN usefulness will be obtained when nonlinear material capabilities are extended to axisymmetric elements and to include provisions for time-dependent material properties and creep analysis. Rigid formats 3 and 5 proved to be very convenient for the buckling and normal-mode analysis of a nuclear fuel element.

Spreeuw, E.↗
NASA NTRS1972

NASTRAN thermal analyzer: A general purpose finite element heat transfer computer program

The program not only can render temperature distributions in solids subjected to various thermal boundary conditions, including effects of diffuse-gray thermal radiation, but is fully compatible in capacity and in the finite-element model representation with that of its structural counterpart in the NASTRAN system. The development history of the finite-element approach for determining temperatures is summarized. The scope of analysis capability, program structure, features, and limitations are given with the objective of providing NASTRAN users with an overall veiw of the NASTRAN thermal analyzer.

Lee, H.↗
NASA NTRS1972

VIEW: A modification of the RAVFAC view factor program for use with the NASTRAN thermal analyzer

The NASTRAN thermal analyzer will include the capability to perform complete thermal analyses on structures. One of the inputs to NASTRAN required to simulate radiative heat transfer between surfaces will be the view factors (also called shape factors, form factors, configuration factors) between those surfaces. The purpose of the VIEW program is to compute these view factors and produce appropriate RADMTX and RADLST output to be used as NASTRAN bulk data.

Puccinelli, E. F.↗
NASA NTRS1972

Design of NASTRAN demonstration problems

Criteria and procedures are supplied for the selection, evaluation, and maintenance of an optimum set of demonstration problems to be used for the purposes of checking out the NASTRAN program and demonstrating NASTRAN's capabilities. Also, suggestions are made for a new demonstration problem manual that will better assist the user community in the selection of NASTRAN options and preparation of input data, as well as allow the user to isolate the various options used in the set of demonstration problems.

Levy, A.↗
NASA NTRS1973

Addition of three-dimensional isoparametric elements to NASA structural analysis program (NASTRAN)

Implementation is made of the three-dimensional family of linear, quadratic and cubic isoparametric solid elements into the NASA Structural Analysis program, NASTRAN. This work included program development, installation, testing, and documentation. The addition of these elements to NASTRAN provides a significant increase in modeling capability particularly for structures requiring specification of temperatures, material properties, displacements, and stresses which vary throughout each individual element. Complete program documentation is presented in the form of new sections and updates for direct insertion to the three NASTRAN manuals. The results of demonstration test problems are summarized. Excellent results are obtained with the isoparametric elements for static, normal mode, and buckling analyses.

Field, E. I.↗
NASA NTRS1973

Intercomputer transfer in full precision of arbitrary data on magnetic tape employing NASTRAN user tape format

A description is presented of two new utility programs which implement the transfer, in full precision, of arbitrary data (matrices or tables) between any of the three NASTRAN operative computers without the handling of large card decks. These computers include the CDC 6000 series, the IBM 360-370 series, and the Univac 1100 series. The data may be generated by NASTRAN or by another computer program if the NASTRAN user tape format is employed.

Rogers, J. L., Jr.↗
NASA NTRS1973

Future NSMO plans for maintenance of NASTRAN

The objectives of the NASTRAN computer program system are discussed. Specific reference is made to the use of NASTRAN in the space shuttle program. The use of NASTRAN by agencies other than NASA is reported. The subjects presented are: (1) planned developments, (2) capability improvements, (3) efficiency improvements, and (4) new error correction procedure.

Weidman, D. J.↗
NASA NTRS1973

NASTRAN analysis of an air storage piping system

The application of NASTRAN to a complex piping design evaluation problem is summarized. Emphasis is placed on structural modeling aspects, problems encountered in modeling and analyzing curved pipe sections, principal results, and relative merits of using NASTRAN as a pipe analysis and design tool. In addition, the piping and manifolding system was analyzed with SNAP (Structural Network Analysis Program). The parallel SNAP study provides a basis for limited comparisons between NASTRAN and SNAP as to solution agreement and computer execution time and costs.

Young, C. P., Jr.↗