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Technical Paper

2-D Springback Analysis for Stretch-Bending Processes Based on Total Strain Theory

A theoretical model is presented for predicting springback of wide sheet metal subjected to 2D-stretch-bending operation. The material is assumed to be normal anisotropic with n-th power hardening law, σ = Fεn. Two types of stretch-bending experiment, bending with simultaneous stretching and stretch-bending followed by consecutive re-stretching, is conducted using AK sheet steel and sheet aluminum alloy A5182-O. The measured values of springback are in good agreement with analytical ones for a wide range of bending radii, stretching forces, and loading conditions. Furthermore, a calculation method for predicting springback configurations of 2D sheet metal parts with arbitrary cross-sections which include both stretch-bending and stretch-bending-unbending deformation is proposed.
Technical Paper

56 Development of two-cylinder liquid-cooled utility gasoline engine models with twin balancer shafts

The new small and lightweight 2-cylinder liquid-cooled OHC gasoline engines were developed. These new engines are featuring high output, low vibration and noise radiation and so able to improve the comfortableness and amenity of applied utility machines. In this paper, the features of the new engines and the process to realize development targets are introduced. The basic structure adopted on the new engines is a liquid-cooled, inline 2-cyilinder layout with 360-degree firing intervals, twin balancer shafts, and an overhead camshaft that is driven by a cogged belt. Also various parts made of aluminum alloy and plastics could make the engine lighter. By these measures, the new engines could satisfy their hardest development targets, and realize their easy installation, higher versatility, and have the excellent features such as compact size, lightweight, high output, low exhaust gas emission and low vibration and noise radiation.
Technical Paper

A Benchmark Test for Springback: Experimental Procedures and Results of a Slit-Ring Test

Experimental procedures and results of a benchmark test for springback are reported and a complete suite of obtained data is provided for the validation of forming and springback simulation software. The test is usually referred as the Slit-Ring test where a cylindrical cup is first formed by deep drawing and then a ring is cut from the mid-section of the cup. The opening of the ring upon slitting releases the residual stresses in the formed cup and provides a valuable set of easy-to-measure, easy-to-characterize springback data. The test represents a realistic deep draw stamping operation with stretching and bending deformation, and is highly repeatable in a laboratory environment. In this study, six different automotive materials are evaluated.
Technical Paper

A Comparative Study on the Performance of Ventilated Brake Discs Manufactured in Different Advanced Materials

Two different aluminium alloy materials have been used to produce ventilated brake discs, on one hand, AS17G0.6 hypereutectic alloy and on the other hand, AS7G0.6 reinforced with 20% in wt. of SiC particles. The casting production technique used has been Low Pressure Casting (LPC) and some of the brake discs have been heat treated using a T6 treatment. Once the ventilated brake discs were produced and machined, they were tested in a dynamometer in order to compare the performance under service conditions of the aluminum alloy and grey cast iron (GCI) discs currently used in the market.
Journal Article

A Comprehensive Plasticity and Fracture Model for Metal Sheets under Multi-axial Stress and Non-Linear Strain Path

A comprehensive plasticity and fracture model was built for metal sheets with application to metal sheet forming and vehicle crash simulations. The combined Bai-Wierzbicki (BW [1]) and CPB06ex2 [2] (or Yld2000-2D [3]) anisotropic plasticity model was further extended to consider elevated temperature effects in additional to the effect of multiaxial stress states. A fully modularized framework was established to combine isotropic, kinematic, and cross hardening behaviors under non-linear loading conditions. The all strain based modified Mohr-Coulomb (eMMC) fracture model was used to consider material anisotropy and nonlinear strain path. The model has been implemented into Abaqus/Explicit as a user material subroutine (VUMAT). Test results on advanced high strength steels, aluminum alloy sheets and magnesium alloy sheets are used to validate the modeling and testing methodologies. Very good correlation was observed between experimental and simulation results.
Technical Paper

A Development of a Light Weight and High Performance Aluminum Radiator

This paper introduces a new type of aluminum radiator that has been developed with the objective of high performance and light weight. Aluminum radiators have recently been replacing copper radiators because of their light weight, but the heat rejection of such conventional alminum radiators does not exceed that of copper radiators. Authors established the aluminum radiator not only being light weight but also having high performance through the following approaches. (1) Optimization of radiator core module. (2) Thickness reduction of tube and fin. (3) Development of aluminum alloys with improved corrosion resistance for tubes and fins. As a result, a new type single-row aluminum radiator has achieved 7% higher rejection at 50% lighter weight than those of copper double-row radiator.
Technical Paper

A Diamond-Like Carbon Coating for Aluminum Alloy Piston/Bore Application

This paper examines the potential use of diamond-like carbon (DLC) on aluminum alloy pistons of internal combustion engines. Our approach is to apply a DLC coating on the piston running against an aluminum-390 bore thus eliminating the iron liners in a standard piston/bore system. Experimental data, using a pin-on-disk tribometer under unlubricated test conditions, indicate that the performance of the DLC coating against aluminum 390 exhibits superior friction resistance compared to aluminum-390 against cast iron; the latter material couple representing the materials currently being used in production for the piston/bore application. Moreover, by thermally cycling the DLC coatings we show that improved friction and wear properties can he maintained to temperatures as high as 400°C.
Technical Paper

A Highly Formable Aluminum Alloy-5182-SSF

The best combination of strength and formability of any aluminum alloy is offered by the 5000 series (Al-Mg) alloys containing 4 to 5% magnesium, e.g. 5182. In the conventional annealed state (-0 temper) necessary for maximum formability, this alloy suffers from the formation of type A Luder lines (stretcher strains) when plastically deformed a small amount (<1%). Such Luder lines are similar to those commonly encountered in steel and are unacceptable in outer panels. The conditions under which Luder lines form are discussed. The introduction of 5182-SSF has completely avoided these problems with a stretcher-strain free (SSF) material which exceeds the formability of 5182-0.
Technical Paper

A Low-cost Modular Small Engine System Utilizing Extruded Aluminum

The use of modularized aluminum extrusions for the block, crankcase and head in small engine systems allows a range of engines to be mass produced without resort to casting for the stationary components. The use of modern accurately dimensioned extrusions greatly reduces the machining required. The versatility and strength of extruded aluminum alloys enables the elimination of load bearing threads and most other finish machining, thus significantly reducing the labor costs of manufacture. A range of strokes and hence of different capacity engines can be produced from a single extrusion form. For extended life, bores can be coated with a variety of finishes, including simple anodizing. Extrusion technology allows cost-effective engines to be manufactured with a significantly lower investment than with other technologies.
Technical Paper

A Multiscale Study of Single Crystal Copper Plate with Octal Orientation Struck by a Nickel Projectile

A common interaction between a penetrator and a target has been the use of copper and nickel materials. However, a multiscale analysis has not been performed on such a system. Compared to steels, aluminum alloys, titanium alloys and other metallic materials, a description of the mechanical behavior of pure ductile metals such as Cu struck by a penetrator comprises nickel under the high strain rate at different multiscale still remains unknown. In this research, Modified Embedded Atom Method (MEAM) Potential is utilized to study this system and the molecular dynamics simulation is employed in order to provide structure property evolution information for plasticity and shearing mechanisms.
Technical Paper

A New Aluminum-Based Bearing Alloy for Slide Type Antifriction Bearings

A new aluminum alloy named 1531 is described. It has been specifically designed for journal bearings of the new families of automotive engines expected to be produced in the second half of the nineties. This new alloy, based on the Al-Sn-Si system, offers improved characteristics as regards resistance to dynamic loading and to wear, in comparison with conventional AlSn20 alloys now used. The foreseen technological production process makes such alloy competitive to overplated Cu-Pb alloys.
Technical Paper

A New Concept Thrust Washer for Gasoline & Diesel Engines

A new concept in thrust washers for gasoline and diesel engines has been developed. Traditionally, thrust washers have been made from the same steel-backed bimetal or trimetal materials that are used for connecting rod bearings and crankshaft main bearings. The new concept is a solid aluminum alloy, specifically formulated for optimum performance as a thrust washer material. This alloy has environmental advantages and performance characteristics superior to currently used materials. The composition, manufacturing process, and microstructure of the new concept thrust washer are briefly explained, and the performance characteristics and environmental advantages are presented.
Technical Paper

A New Evaluation Method for the Measurement of Internal Corrosion Resistance in Braze Clad Alloys

Historically, the development of brazing alloys for heat exchangers has focused on improving mechanical properties, improving external corrosion resistance and retaining good brazeability. Recently, the interest has been in the measurement of internal corrosion resistance and the development of aluminum alloys that will provide good internal corrosion resistance. Previously, testing to determine the internal corrosion resistance was performed on full size units. Herein is a description of an internal corrosion test loop, which has been designed and manufactured for testing internal corrosion resistance on small coupons of material. The test results for the coupons have been compared to those of a full size radiator that was exposed simultaneously with the coupons in the same corrosion test loop. The similarity between the results validates the ability of the system to test sheet specimens prior to production trials.
Technical Paper

A New Measurement of Aluminum Alloy Edge Stretching Limit Based on Digital Image Correlation Method

In Aluminum Alloy, AA, sheet metal forming, the through thickness cracking at the edge of cut out is one of the major fracture modes. In order to prevent the edge cracking in production forming process, practical edge stretch limit criteria are needed for virtual forming prediction and early stamping trial evaluations. This paper proposes new methods for determining the edge stretching limit of the sheet coupons, with and without pre-stretching, based on the Digital Image Correlation (DIC) technique. A numbers of sets of notch-shaped smaller coupons with three different pre-stretching conditions (near 5%, 10% and fractured) are cut from the prestretched large specimens. Then the notch-shaped smaller coupons are stretched by uniaxial tension up to through edge cracking observed. A dual-camera 3D-DIC system is utilized to measure both coupon face strain and thickness strain in the notch area at the same time.
Technical Paper

A New Paint-Bake-Hardenable Aluminum Alloy for Auto Body Sheet Applications

A new 5xxx-series aluminum alloy, which was designed to have an excellent paint-bake-hardenability with practically no room-temperature aging, has been developed for automobile body sheets. The alloy contains 2∼3%Mg with additional amounts of Cu and Si. Yield strength in the as-shipped condition is very low, 80∼100MPa, but it can be increased by as much as about 60MPa through 2% stretch and paint-bake at 170°C. Such an excellent response to paint-bake was revealed to result from Guinier-Preston-Bagaryatskii(GPB) zone formation and enhanced by the optimum addition of Si. Density of vacancies in the alloy was reduced through a special annealing process to suppress room-temperature aging. Press-forming for fender outer and engine hood inner panels was done, and the alloy was demonstrated to have formability superior to 6xxx-series alloys and Al-4.5%Mg alloys, due to the reduced initial yield strength which also suppressed susceptibility to spring back.
Technical Paper

A New V-8 Engine for the LEXUS LS 400

A new 4.0 liter V8 engine, 1UZ-FE, has been developed for the luxury sedan, LEXUS LS400. The engine has 4 camshafts and 32 valves, and weighs only 195 kg (430 lbs) having many light alloy components and carefully designed configurations. The appropriate engine displacement and high technology adopted throughout from design to manufacturing process enable the LS400 to run powerfully with excellent fuel economy and a pleasant sounds. It develops 250HP at 5600 rpm and 260ft-lbs of torque at 4400 rpm, and its fuel economy figure, well exceeds the EPA's tax charge level of 22.5mpg. These figures have been achieved through the newest technologies applied to every part of the design, such as: Well studied intake and exhaust systems, centrally located spark plug in the TOYOTA original four-valve combustion chamber, which has a narrow valve including angle, and low friction components like aluminum alloy valve lifters and well balanced moving parts.
Technical Paper

A Novel Approach for Rapid Solidification Processing of High Strength PM Aluminum Alloys

Incremental spray casting has been applied to the consolidation of advanced high strength aluminum alloys requiring rapid solidification processing. The conditions for incremental spray casting are described and compared with the spray rolling process as proposed originally by A. R. E. Singer. Microstructures and tensile properties of the aluminum alloys 7075, 7091, and PM64 prepared by incremental spray casting and subsequently rolled and heat treated are presented and compared with their conventionally prepared counterparts. This process provides a direct route from pre-alloyed melt stock to sheet bar; it is a promising alternative to conventional powder metallurgy methods for producing a dense, rapidly solidified deposit of high strength PM aluminum alloy. At the present time the process is limited to producing deposit thicknesses of about 1 to 2 cm. Improved methods of extracting heat from the solidifying deposit are required for scaleup to thicker sections.
Technical Paper

A Realistic Friction Test for Sheet Forming Operations

A new technique for measuring the friction coefficient between the punch and workpiece during sheet forming operations has been developed at the Ohio State University. Various materials, such as interstitial-free (IF) steel, high strength (HS) steel, an aluminum alloy (2008T4) and 70/30 brass, were tested under dry and oil lubrication conditions at different punch rates and process conditions. The results show that punch friction depends on the angle of wrap, which varies with punch stroke, and on the strain rate, which depends on punch velocity. The O.S.U. Friction Test is described and typical results are presented which verify the usefulness of the new procedure.
Technical Paper

A Study of Erosion-Corrosion in Aluminum Radiator Alloys

The frequent occurrence of erosion-corrosion attack in service failures of aluminum radiators suggests the need for a rapid test which will predict erosion-corrosion susceptibility in aluminum alloys under conditions simulating those in an actual radiator. This paper describes a multijet test apparatus which has been used to compare the erosion-corrosion resistance of aluminum alloys in antifreeze solutions at 200 F. Impingement velocities of up to 130 ft/s have been used. The effect of short-term jet impingement has been found to produce a mode of erosion-corrosion attack similar to that found in a 6951 alloy radiator after 40,000 miles of service. Attack appears to progress through several distinct stages starting with the development of a high density of pits which eventually become coalesced together at points of very high impingement velocity. The rate of attack has been found to be dependent on alloy composition and properties, jet velocity, and metal surface condition.