Engineering topics

Bales, Thomas T.

Publications and source records attributed to Bales, Thomas T..

9 records

NASA NTRS2019

Structural Framework for Flight II: NASA’s Role in Development of Advanced Composite Materials for Aircraft and Space Structures

This monograph is organized to highlight the successful application of light alloys on aircraft and space launch vehicles, the role of NASA in enabling these applications for each different class of flight vehicles, and a discussion of the major advancements made in discipline areas of research. In each section, key personnel and selected references are included. These references are intended to provide additional information for technical specialists and others who desire a more in-depth discussion of the contributions. Also in each section, lessons learned and future challenges are highlighted to help guide technical personnel either in the conduct or management of current and future research projects related to light-weighting advanced air and space vehicles.

Tenney, Darrel R.↗

NASA NTRS2007

Development and Processing Improvement of Aerospace Aluminum Alloys

This final report, in multiple presentation format, describes a comprehensive multi-tasked contract study to improve the overall property response of selected aerospace alloys, explore further a newly-developed and registered alloy, and correlate the processing, metallurgical structure, and subsequent properties achieved with particular emphasis on the crystallographic orientation texture developed. Modifications to plate processing, specifically hot rolling practices, were evaluated for Al-Li alloys 2195 and 2297, for the recently registered Al-Cu-Ag alloy, 2139, and for the Al-Zn-Mg-Cu alloy, 7050. For all of the alloys evaluated, the processing modifications resulted in significant improvements in mechanical properties. Analyses also resulted in an enhanced understanding of the correlation of processing, crystallographic texture, and mechanical properties.

Lisagor, W. Barry↗

NASA NTRS2007

Development and Processing Improvement of Aerospace Aluminum Alloys-Development of AL-Cu-Mg-Ag Alloy (2139)

This final report supplement in presentation format describes a comprehensive multi-tasked contract study to continue the development of the silver bearing alloy now registered as aluminum alloy 2139 by the Aluminum Association. Two commercial scale ingots were processed into nominal plate gauges of two, four and six inches, and were extensively characterized in terms of metallurgical and crystallographic structure, and resulting mechanical properties. This report includes comparisons of the property combinations for this alloy and 2XXX and 7XXX alloys more widely used in high performance applications. Alloy 2139 shows dramatic improvement in all combinations of properties, moreover, the properties of this alloy are retained in all gauge thicknesses, contrary to typical reductions observed in thicker gauges of the other alloys in the comparison. The advancements achieved in this study are expected to result in rapid, widespread use of this alloy in a broad range of ground based, aircraft, and spacecraft applications.

Cho, Alex↗

NASA NTRS1994

Fabricating Structural Stiffeners By Superplastic Forming

Superplastic forming (SPF) of aluminum alloys effective technique for making strong, lightweight structural components conforming to close dimensional tolerances. Technique applied in experimental fabrication of prototypes of stiffening ribs for cylindrical tanks. When making structural panel, stiffening ribs spot-welded to metal skin. Use of discrete eliminates machining waste, and use of SPF. Cost of fabrication reduced.

Bales, Thomas T.↗

NASA NTRS1992

Airframe materials for HSR

Vugraphs are presented to show the use of refractory materials for the skin of the High speed Civil Transport (HSCT). Examples are given of skin temperature ranges, failure mode weight distribution, tensile properties as a function of temperature, and components to be constructed from composite materials. The responsibilities of various aircraft companies for specific aircraft components are defined.

Bales, Thomas T.↗

NASA NTRS1991

Test of superplastically formed corrugated aluminum compression specimens with beaded webs

Corrugated wall sections provide a highly efficient structure for carrying compressive loads in aircraft and spacecraft fuselages. The superplastic forming (SPF) process offers a means to produce complex shells and panels with corrugated wall shapes. A study was made to investigate the feasibility of superplastically forming 7475-T6 aluminum sheet into a corrugated wall configuration and to demonstrate the structural integrity of the construction by testing. The corrugated configuration selected has beaded web segments separating curved-cap segments. Eight test specimens were fabricated. Two specimens were simply a single sheet of aluminum superplastically formed to a beaded-web, curved-cap corrugation configuration. Six specimens were single-sheet corrugations modified by adhesive bonding additional sheet material to selectively reinforce the curved-cap portion of the corrugation. The specimens were tested to failure by crippling in end compression at room temperature.

Davis, Randall C.↗

NASA NTRS1990

Superplastically Formed Titanium Hat-Stiffened Panels

Recent advances in superplastic forming of some metals make it possible to fabricate new shapes. Superplastic forming enables design of structures using mass more efficiently. Parts having intersecting compound contour surfaces made; impossible to fabricate such parts by more conventional methods. Beaded hat-stiffened panel has higher critical buckling strain than conventional hat-stiffened panel.

Davis, Randall C.↗

NASA NTRS1987

Analysis and test of superplastically formed titanium hat-stiffened panels under compression

Four hat-stiffened titanium panels with two different stiffener configurations were fabricated by superplastic forming/weld brazing and tested under a moderately heavy compressive load. The panels had the same overall dimensions but differed in the shape of the hat-stiffener webs; three panels had stiffeners with flat webs and the other panel had stiffeners with beaded webs. Analysis indicated that the local buckling strain of the flat stiffener web was considerably lower than the general panel buckling strain or cap buckling strain. The analysis also showed that beading the webs of the hat stiffeners removed them as the critical element for local buckling and improved the buckling strain of the panels. The analytical extensional stiffness and failure loads compared very well with experimental results.

Davis, Randall C.↗

NASA NTRS1987

Superplastic forming/weld-brazing of Ti-6Al-4V panels for enhanced structural efficiency

An account is given of the results obtained by NASA-sponsored studies which exploit the processing advantages of superplastic forming (SPF) and joining by weld-brazing (WB) for the fabrication of Ti-alloy skin-stiffened structural components. The buckling strengths of panels with stiffeners having the geometry of a conventional hat shape are compared with those of panels having advanced-geometry stiffereners. Both single- and multiple-stiffened panels have been evaluated at room temperature; the SPF/WB panels with advanced-geometry stiffeners developed up to 60-percent higher buckling strength than panels with conventional-geometry stiffeners. Selective stiffener reinforcement with a boron-reinforced Al-matrix MMC was also evaluated.

Royster, Dick M.↗