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At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1926

Wing spar stress charts and wing truss proportions

In order to simplify the calculation of beams continuous over three supports, a series of charts have been calculated giving the bending moments at all the critical points and the reactions at all supports for such members. Using these charts as a basis, calculations of equivalent bending moments, representing the total stresses acting in two bay-wing trusses of proportions varying over a wide range, have been determined, both with and without allowance for column effect. This leads finally to the determination of the best proportions for any particular truss or the best strut locations in any particular airplane. The ideal proportions are found to vary with the thickness of the wing section used, the aspect ratio, and the ratio of gap to chord.

Warner, Edward P↗
NASA NTRS1940

The Strength of Shell and Tubular Spar Wings

The report is a survey of the strength problems arising on shell and tubular spar wings. The treatment of the shell wing strength is primarily confined to those questions which concern the shell wing only; those pertaining to both shell wing and shell body together have already been treated in TM 838. The discussion of stress condition and compressive strength of shell wings and tubular spar wings is prefaced by several considerations concerning the spar and shell design of metal wings from the point of view of strength.

Ebner, H↗
NASA NTRS1925

Calculation of wing spars of variable cross-section and linear load

The calculation of wing spars of constant cross-section and load has been thoroughly treated by a large number of authors. Such is not the case,however, regarding the calculation of wing spars whose section and linear load diminish toward the ends, as in wings of trapezoidal contour and decreasing section.

SPARS↗
NASA NTRS1927

Approximations for column effect in airplane wing spars

The significance attaching to "column effect" in airplane wing spars has been increasingly realized with the passage of time, but exact computations of the corrections to bending moment curves resulting from the existence of end loads are frequently omitted because of the additional labor involved in an analysis by rigorously correct methods. The present report represents an attempt to provide for approximate column effect corrections that can be graphically or otherwise expressed so as to be applied with a minimum of labor. Curves are plotted giving approximate values of the correction factors for single and two bay trusses of varying proportions and with various relationships between axial and lateral loads. It is further shown from an analysis of those curves that rough but useful approximations can be obtained from Perry's formula for corrected bending moment, with the assumed distance between points of inflection arbitrarily modified in accordance with rules given in the report. The discussion of general rules of variation of bending stress with axial load is accompanied by a study of the best distribution of the points of support along a spar for various conditions of loading.

Warner, Edward P↗
NASA NTRS1940

Stresses in single-spar wing constructions with incompletely built-up ribs

It is shown that the force distribution resulting from incomplete ribs in single spar wing structures may be determined with the aid of the shear field method by a statistically indeterminate computation. A numerical computation is given of the force distribution of a wing structure whose two neighboring incomplete ribs with web missing in half the section are torsionally loaded.

Reinitzhuber, F↗
NASA NTRS1931

Metal-truss wing spars

The purpose of the study was to develop improvements in the current methods for the calculation of the loads in members of metal truss wing spars which are subjected to combined bending and compression. The theory developed here has two important practical applications. One is the calculation of the effective moment of inertia of a truss spar from the geometry of the spar and the loads to which the spar is to be subjected. The second is the determination of the most economical location of metal for stiffening a truss spar which has too much deflection.

Swickard, Andrew E↗
NASA NTRS2019

Structural Analysis and Performance-Based Validation of a Composite Wing Spar

Electric-motor powered aircraft possess the ability to operate with efficient energy delivery, but lack the operational range of internal combustion engine powered aircraft. This range limitation requires the use of high aspect ratio, thin-chord wings to minimize aerodynamic drag losses, which results in highly loaded composite spar structures. High aspect ratio wings are required to increase mission durations for a NASA-developed experimental multi-rotor electric powered aircraft denoted as the Scalable Convergent Electric Propulsion Technology and Operations Research (SCEPTOR) or “X-57”. This paper examines the structural performance of the composite main wing spars to validate spar strength using ply-based laminate finite element methods. Geometric scaling of a main spar test-section was initially proposed for proof-testing but sacrificed stability. Ply-based structures modeling with local structural features was implemented as a risk-reduction methodology. Ply-based modeling was selected to augment the conventional “building block” approach to reduce risk, and leverage a “performance-based” approval processes encouraged in Federal Aviation Administration (FAA) design guidance. Therefore, ply-based laminate modeling of the full-scale main spar and forward spar shear-web attachments were subsequently undertaken to determine load path complexity with predicted flight loads. Ply-based modeling included stress concentrations and interlaminate behavior at interface locations that can be obscured in traditional finite element sizing models. Analysis of the wing spar laminate ply-based models compared with bearing test coupon performance was used to reduce future wing assembly proof-testing burden and facilitate performance-based flight hardware safety for the X-57 experimental aircraft.

Moore, James B.↗
NASA NTRSDate not supplied

Refill Friction Stir Spot Welding as an Alternative Joining Method for Wing Spar Structures

Since the introduction of refill friction stir spot welding (RFSSW) in the early 2000s, numerous evaluations of properties, performance, and prototypes have been documented. RFSSW is a solid-state spot joining technique that is being evaluated as a rivet replacement technology for aerospace structures and fuselage fabrication. A production evaluation of overlapping wing skin assembly was completed and experimentation on stringer-stiffened curvilinear panels is underway. Weld properties were evaluated for spots produced on bare sheet as well as for sections with sealant applied. Furthermore, evaluations of the performance of repaired spots using the RFSSW process is demonstrated. Characterization of the weld interface, heat-affected zone, and complete through-thickness consolidation via computed tomography is presented.

Solid-state joining↗
NASA NTRS1921

Calculation of wing spars

The author presents a comparison and combination of the numerical and geometrical determinations of the maximum M, when calculating the maximum bay moment.

Muller-Breslau, H↗
NASA NTRS1921

Calculation of wing spars

The author presents a comparison and combination of the numerical and geometrical determinations of the maximum M, when calculating the maximum bay moment.

Muller-Breslau, H↗
NASA NTRS1972

A parametric study of planform and aeroelastic effects on aerodynamic center, alpha- and q-stability derivatives. Appendix E: Procedures used to determine the structural representation for idealized low aspect ratio two spar fighter wings

An explanation is presented of the method used to locate the elastic axis and the method to determine the EI and GJ distributions along the elastic axes of wings with a 2-spar (front and rear) construction or a single torque-box construction.

Roskam, J.↗
NASA NTRS1936

Analysis of 2-spar cantilever wings with special reference to torsion and load transference

This report deals with the analysis of 2-spar cantilever wings in torsion, taking cognizance of the fact that the spars are not independent, but are interconnected by ribs and other structural members. The principles of interaction are briefly explained, showing that the mutual relief action occurring depends on the "pure torsional stiffness" of the wing cross section. Various practical methods of analysis are outlined. The "Friedrichs-Von Karman equations" are shown to require the least amount of labor. Numerical examples by the several methods of analysis are given and the agreement between the calculation and experiment is shown.

Kuhn, Paul↗
NASA NTRS2010

Methods for In-Flight Wing Shape Predictions of Highly Flexible Unmanned Aerial Vehicles: Formulation of Ko Displacement Theory

The Ko displacement theory is formulated for a cantilever tubular wing spar under bending, torsion, and combined bending and torsion loading. The Ko displacement equations are expressed in terms of strains measured at multiple sensing stations equally spaced on the surface of the wing spar. The bending and distortion strain data can then be input to the displacement equations to calculate slopes, deflections, and cross-sectional twist angles of the wing spar at the strain-sensing stations for generating the deformed shapes of flexible aircraft wing spars. The displacement equations have been successfully validated for accuracy by finite-element analysis. The Ko displacement theory that has been formulated could also be applied to calculate the deformed shape of simple and tapered beams, plates, and tapered cantilever wing boxes. The Ko displacement theory and associated strain-sensing system (such as fiber optic sensors) form a powerful tool for in-flight deformation monitoring of flexible wings and tails, such as those often employed on unmanned aerial vehicles. Ultimately, the calculated displacement data can be visually displayed in real time to the ground-based pilot for monitoring the deformed shape of unmanned aerial vehicles during flight.

Ko, William L.↗
NASA NTRS2019

Shape Sensing for Wings with Spars and Ribs Using Simulated Strain

Active trim shape control can be used to minimize error between target and actual aircraft trim shape during flight. Trim shape sensing for aircraft during flight is not only important for highly flexible aircraft, such as the National Aeronautics and Space Administration (NASA) Helios Prototype remotely piloted flying wing aircraft, but also for a delta-wing type aircraft, such as a supersonic commercial transport aircraft. A two-step theory utilizing distributed strain for a real-time shape sensing of a full three-dimensional structure has been introduced previously. This study focuses on the application of the two-step theory to finite element models of a wing with spars and ribs such as the X-59 QueSST aircraft (Lockheed Martin Corporation, Bethesda, Maryland), a tapered wing, a dihedral/anhedral wing, and a stiffened dihedral/anhedral wing. A finely meshed finite element structural model is desired to capture accurate curvature distributions along the neutral axes of the wing cross sections during pre-test analysis for shape sensing of a wing with ribs and spars. The two-step theory used in this study gives excellent deformation correlation with the MSC/NASTRAN (MSC Software, Newport Beach, California) results along the neutral axis for all test cases used in this study except the X-59 QueSST aircraft.

strain↗