Generalized stiffness matrix of a curved-beam element
Stiffness matrix derivation for curved beam emphasizing uncoupled normal to plane loads
Lee, H.-P.↗
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SAMMSOR 2 - A finite element program to determine Stiffness And Mass Matrices of Shells Of Revolution
Finite element program for determining stiffness and mass matrices of shells of revolution - users manual
Haisler, W. E.↗
The effects of nonuniform swash-plate stiffness on coupled blade-control system dynamics and stability. Part 2 - Computer program listing
Computer program for calculating effects of swash-plate stiffness on helicopter rotor system dynamics and stability
Piarulli, V. J.↗
Non-linear Consideration of Gravity in a Stiffness Test of a Weak Structure at Small Strains
NASTRAN computer program used to calculate lateral deflections of weak spacecraft antenna boom to determine stiffness at small strains
Barclay, R. G.↗
NASTRAN Differential Stiffness Analysis of an Aircraft Canopy
NASTRAN computer program differential stiffness and static load analysis methods compared for aircraft tandem side opening canopies
Bennett, R. D.↗
Development and evaluation of solution procedures for geometrically nonlinear structural analysis by the direct stiffness method
Numerical solution procedures evaluation for geometrically nonlinear structural analysis by direct stiffness method, noting capability of self correcting initial value formulation
Haisler, W. E.↗
Geometrically nonlinear structural analysis by direct stiffness method
Modified Newton-Raphson stiffness matrices and initial value formulations to geometrically nonlinear structural analysis for beam and plane stress triangular elements
Haisler, W. E.↗
Effects of nonuniform swash-plate stiffness on coupled blade-control system dynamics and stability
Program has been developed that analytically determines effects of nonuniform swash-plate support stiffness, swash-plate flexibility, and out-of-blade track on vibratory mechanical stability characteristics of helicopter rotor systems. Analysis is based on combined Laplace transform and associated matrix approach.
Piarulli, V. J.↗
Thermal effects on the clearance and stiffness of foil journal bearings for a Brayton cycle turboalternator
An analysis of foil journal bearings for a NASA Brayton Cycle Unit (BRU) is presented. The study represents an extension of previous work in that it includes the effects of thermal expansion of foil-bearing components, as well as an improved model of the influence of foil flexure. The results presented give the bearing film thickness, the bearing stiffness, and the foil tension as functions of the operating temperatures and the elasto-hydrodynamic and geometrical parameters pertinent to the design of BRU foil bearings. A computer program for the evaluation of design data and for parametric studies is included.
Eshel, A.↗
Derivation of mass and stiffness matrices from dynamic test data.
A technique is described by which orthonormal modal vectors, computed from dynamic test response data, are used to derive mass, stiffness, and damping matrices for a discrete model of the distributed elastic system. Matrices thus computed from subsystems tests may be readily incorporated into larger system models. The method has been applied to a test of the Saturn V S-II stage LOX tank-engine support system. The dynamic responses of the discrete model are shown to correlate well with test data throughout the frequency range tested.
Thoren, A. R.↗
Engineering analysis and test results of the pre-stage planetary gear trains for wrist rotation and pitch assembly and azimuth and elevation assembly of the extendable stiff arm manipulator kit assembly
In order to improve the performance capability of the Extendable Stiff Arm Manipulator (ESAM) it was necessary to increase the overall gear ratio by a factor of approximately four. This is accomplished with minimum effect to existing hardware by the interposition of a planetary gear transmission between the respective drive motors and the harmonic drive transmissions. The engineering analysis in support of this design approach and the subsequent no-load test results are reported.
Morris, R. N.↗
Evaluation of experimental methods for determining dynamic stiffness and damping of composite materials
Various methods potentially usable for determining dynamic stiffness and damping of composite materials are reviewed. Of these, the following most widely used techniques are singled out for more detailed discussion: free vibration, pulse propagation, and forced vibration response. To illustrate the usefulness and validity of dynamic property data, their application in dynamic analyses and comparison with measured structural response are described for the following composite-material structures: free-free sandwich beam with glass-epoxy facings, clamped-edge sandwich plate with similar facings, free-end sandwich conical shell with similar facings, and boron-epoxy free plate with layers arranged at various orientations.
Bert, C. W.↗
A note on the effect of bending stiffness of stringers attached to a plate with a crack
An infinite stringer partially bonded to a plate through a layer of adhesive is considered. The stringer had bending as well as longitudinal stiffness. The effect of the stringer's bending rigidity on the stress intensity factor at the tip of the crack is illustrated. Shear stress distribution between the plate and the stringer and the stress intensity factors are obtained from the solution of a system of Fredholm integral equations. The continuity of displacements along the line of bond is represented by the equations.
Arin, K.↗
A Study of the Effect of Adhesive and Matrix Stiffnesses on the Axial, Normal, and Shear Stress Distributions of a Boron-epoxy Reinforced Composite Joint
The mechanical properties of a symmetrical, eight-step, titanium-boron-epoxy joint are discussed. A study of the effect of adhesive and matrix stiffnesses on the axial, normal, and shear stress distributions was made using the finite element method. The NASA Structural Analysis Program (NASTRAN) was used for the analysis. The elastic modulus of the adhesive was varied from 345 MPa to 3100 MPa with the nominal value of 1030 MPa as a standard. The nominal values were used to analyze the stability of the joint. The elastic moduli were varied to determine their effect on the stresses in the joint.
Howell, W. E.↗
Pressure deformation of tires using differential stiffness for triangular solid-of-revolution elements
The derivation is presented of the differential stiffness for triangular solid of revolution elements. The derivation takes into account the element rigid body rotation only, the rotation being about the circumferential axis. Internal pressurization of a pneumatic tire is used to illustrate the application of this feature.
Chen, C. H. S.↗
Analysis of twisting stiffness for a multifiber composite layer
The twisting stiffness of a rectangular cross section consisting of a single row of solid circular cross-section fibers embedded in a matrix is analyzed. The problem is formulated as a Dirichlet torsion problem of a multielement region and solved by the boundary-point least-squares method. Numerical results for a single-fiber square cross section compare favorably with previous relaxation-method results. New numerical results for three and five-fiber composites suggest that the torsional rigidity of a multifiber composite can be approximated from the torsional rigidities of single and three-fiber models.
Bert, C. W.↗
A note on the effect of lateral bending stiffness of stringers attached to a plate with a crack
An infinite stringer which is assumed to be partially bonded to a plate through a layer of adhesive is considered. The stringer is assumed to have bending as well as longitudinal stiffness. The effect of the stringer's bending rigidity on the stress intensity factor at the tip of the crack is illustrated. Shear stress distribution between the plate and the stringer and the stress intensity factors will be obtained from the solution of a system of Fredholm integral equations which represent the continuity of displacements along the line of bond.
Arin, K.↗
Relative stiffness of flat conductor cables
The measurement of the bending moment required to obtain a given deflection in short lengths of flat conductor cable (FCC) is presented in this report. Experimental data were taken on 10 different samples of FCC and normalized to express all bending moments (relative stiffness factor) in terms of a cable 5.1 cm (2.0 in.) in width. Data are presented in tabular and graphical form for the covenience of designers who may be interested in finding torques exerted on critical components by short lengths of FCC.
Hankins, J. D.↗