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Technical Paper

Weldbond and its Performance in Aluminum Automotive Body Sheet

1975-02-01
750462
IN WELDBONDING, a joint is produced by (a) spotwelding through an uncured adhesive bondline or (b) flowing adhesive by capillary action into the bond area after spotwelding. Weldbonding can offer higher joint strength, reduced joint weight, improved fatigue life and, in some aircraft-oriented investigations, showed reduced manufacturing costs(1,2). Although weldbonding has had repeated use in the Russian aircraft industry(3,4), it has not been widely employed in American manufacturing to date. The most intensive efforts to develop the process have resulted from contracts sponsored by the U. S. Air Force(4). The only aluminum alloys used in these investigations were the high strength aircraft alloys and the emphasis was to develop the highest strength weldbond joints with economics a secondary consideration. These studies usually included the use of special surface treatments on the aluminum, special adhesives, and carefully controlled curing conditions.
Technical Paper

Verification of Crystallographic Texture Based FLD Predictions for Aluminum Sheet

1995-02-01
950701
Determination of forming limit diagrams (FLDs) by experimental methods requires a significant amount of time and expertise in interpretation of data. Their construction can be especially difficult for aluminum alloys due to slightly negative or near zero strain rate sensitivity characteristics which create sharp strain gradients. For this reason a mathematical model which incorporates microstructural attributes, namely crystallographic texture, with a description of strain hardening behavior was developed by Barlat1 to predict the forming limit strains for a given material. Using Barlat, forming limit diagrams were predicted for various automotive body sheet alloys and verified against experimental data. Excellent correlation was found between the experimental and predicted diagrams. Prediction of limit strains requires approximately one-tenth of the time required for experimental diagrams and eliminates variations associated with experimental determination techniques.
Technical Paper

Tool Material Performance During Draw Bead Deformation of Aluminum Sheet

1996-02-01
960820
Draw bead simulator tests were performed on various tool materials using aluminum alloys 2008-T4 and 6111-T4. The tool materials included hardened cast steel J435/0050A, D2 alloy, cast steel with ion nitride and PVD chromium nitride surface treatments, and cast steel with standard chromium and Wearalloy™ chromium coatings. Friction and galling behavior were monitored over an extended period of testing which allowed differentiation of the tool materials and alloys. Wearalloy™ and CrN tool coatings consistently demonstrated improved ability to prevent material transfer for both aluminum alloys, in spite of friction coefficients which were higher than the uncoated and ion nitrided tools. The ion nitrided surface exhibited the lowest friction coefficients of the surface treatments tested, but showed appreciably more wear. For a given lubricant and dilution ratio, alloy 2008-T4 exhibited an increased tendency for material transfer compared to alloy 6111-T4 for all tool materials tested.
Technical Paper

The Development/Application of Sheet Metal Forming Technology at Alcoa

1993-03-01
930523
The advent of high speed computers permits the use of the finite element method to model complex sheet metal forming processes on a reasonable time scale. The design and development of sheet metal parts in the automotive industry and the need for improved sheet forming processes and reduced part development cost have led to the use of computer simulation in tool/die design of sheet metal pressings. An accurate constitutive description of plastic anisotropic yield loci and work hardening of material behavior in sheet forming is now a reality. The constitutive equation developed at Alcoa for describing anisotropic material behavior is consistent with polycrystalline plasticity, and it is expected to improve the computational accuracy of forming process for polycrystalline metals and alloys.
Technical Paper

Recycling of Automotive Aluminum - Present and Future

1983-02-01
830099
About 70% of the 740 million pounds of aluminum in U.S. cars scrapped in 1982 will be recovered for the secondary aluminum industry, making cars second only to used beverage containers as a source of old aluminum scrap. By the late 1990’s aluminum could supersede ferrous materials as the component with the highest total scrap value in the car. To fully realize this value, the automotive scrap industry will probably move from methods primarily designed to recover ferrous values toward practices which decrease the mixing of materials that presently limits recovery and value for aluminum. Today’s system for recycle of used aluminum beverage cans could foreshadow development of a means for recycling automotive aluminum back to primary aluminum producers. This could be accomplished by increasing dismantling and by identification and segregation of aluminum components by alloy.
Technical Paper

New 6XXX-Series Alloys for Auto Body Sheet

1977-02-01
770307
Two new aluminum alloys, 6009 and 6010, for auto body sheet are described and technical data are presented. The 6XXX-series alloys are ideal for body sheet in several respects, providing excellent corrosion resistance, improved spot weldability, and freedom from Luder's lines, together with favorable response to aging in many paint bake cycles. The result is a combination of excellent formability in the T4 temper and, after aging, higher strength than achievable in any other aluminum alloy system having other characteristics desired in body sheet. The latter translates to excellent dent resistance, superior even to that of steel. Furthermore, scrap loop problems are eliminated; compatible alloys 6009 and 6010 may be used together to obtain optimum strength and formability without any penalties in scrap utilization. Forming, aging, finishing, and joining data for these alloys are presented.
Technical Paper

Microstructural Material Models for Fatigue Design of Castings

1996-02-01
960161
Classically, structural component fatigue design is based on testing and empirical models. First a series of average stress-life curves are generated from fatigue tests. Constant life diagrams are then developed accounting for mean stress effect, casting quality, surface finish, volume and other factors. Component design is then based on keeping the effective alternating stress below the diagram limit stress. While this procedure has worked well to design many components, it is based on extensive fatigue testing and empirical stress reduction factors. Thus, material and process improvements and computerization of the design process are difficult to incorporate into this test/empirical based design methodology. Fracture mechanics and damage tolerant design methodologies are used in aerospace for fatigue design. These methods predict well the fatigue life for surface scratches (rogue inspectable flaws) of about 0.25-1.27 mm in size.
Technical Paper

Metallurgical Factors Related to Machining Aluminum Castings

1967-02-01
670465
Three metallurgical factors have a major influence on the machinability of aluminum castings: chemical composition, heat treatment, and foreign inclusions. Othermet-allurgical factors that may also affect machinability are generally related to one of these three items. In general, aluminum alloys have good machining characteristics, although tests indicate that they cover a range. Some of the differences that do exist are discussed and practices identified that lead to improved machinability.
Technical Paper

Evaluation of Various Yield Criteria in LS-DYNA3D for Sheet Forming Application for Aluminum

1995-02-01
950925
Finite element modeling of sheet forming processes for complex automotive parts using an explicit dynamic code such as LS-DYNA3D is increasingly used for producibility analysis and die development. In modeling sheet metal forming processes, it is very common to represent material behavior by either Von Mises' or Hill's yield criterion using commercial finite element codes. However, these criteria do not provide an accurate representation of aluminum alloys. Recently, a new yield criterion proposed by Barlat has been incorporated into LS-DYNA3D to describe the anisotropic material behavior of aluminum alloys. This paper examines the influence of Von Mises', Hill's (1948) and Barlat's yield criteria on the FEM simulation results for the deep drawing of a square cup and cylindrical cup for aluminum alloys. The sensitivity of predicted results to yield criteria is examined for deformation behavior, strain localization and potential of wrinkling.
Technical Paper

Design Considerations for Aluminum Fasteners

1980-02-01
800455
Weight considerations and the need for corrosion resistance make aluminum fasteners attractive for new automotive design. This paper reviews design considerations in using aluminum fasteners. Newly developed high-strength fastener alloys complimented by lightweight and the well known attributes of aluminum give the designer wide latitude in using aluminum for standard and special purpose fasteners.
Technical Paper

Aluminum Automotive Recycling and Materials Selection Issues

1993-03-01
930493
Different scenarios for aluminum usage in automotive body structure are examined with emphasis on the potential effects on recycling. Alloy selection issues are addressed with regard to the limits on absorption of recycled automotive scrap into new cast or wrought products. The difference between “open loop” and “closed loop” recycling is discussed. Possible impacts of increased aluminum usage on the needs for separation technology and recycling infrastructure are reviewed briefly.
Technical Paper

ALUMINUM ENGINES—design for modern fabrication

1959-01-01
590037
ALUMINUM engines promise a gain in the power/weight ratio and possibilities of production economies. Aluminum has already proved its value for some parts; only the adaptation of design for high production methods delays full realization of the metal's potentials. This paper describes the problems encountered in adapting the V-type engine to fabrication methods using aluminum alloy parts. Applications of aluminum in crankcase and cylinder block, cylinder liners and heads, intake manifold, pistons, and bearings are also discussed.
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