Criteria

Text:
Topic:
Display:

Results

Viewing 1 to 30 of 1821
2010-04-12
Technical Paper
2010-01-0405
David A. Wagner, Stephen Logan, Kangping Wang, Timothy Skszek
Finite element analysis (FEA) predictions of magnesium beams are compared to load versus displacement test measurements. The beams are made from AM60B die castings, AM30 extrusions and AZ31 sheet. The sheet and die cast beams are built up from two top hat sections joined with toughened epoxy adhesive and structural rivets. LS-DYNA material model MAT_124 predicts the magnesium behavior over a range of strain rates and accommodates different responses in tension and compression. Material test results and FEA experience set the strain to failure limits in the FEA predictions. The boundary conditions in the FEA models closely mimic the loading and constraint conditions in the component testing. Results from quasi-static four-point bend, quasi-static axial compression and high-speed axial compression tests of magnesium beams show the beam's behavior over a range of loadings and test rates. The magnesium beams exhibit significant material cracking and splitting in all the tests.
2010-04-12
Technical Paper
2010-01-0408
Qiang Zhang, Henry Hu
In the past decade, magnesium (aluminum) alloy use in the automotive industry has increased in order to reduce vehicle weight and fuel consumption. However, their applications are usually limited to temperatures of up to 120°C. Improvements in the high-temperature mechanical properties of magnesium alloys would greatly expand their industrial applications. As compared to the unreinforced monolithic metal, metal matrix composites have been recognized to possess superior mechanical properties, such as high elastic modulus and strengths as well as enhanced wear resistance. In this study, a novel approach of making hybrid preforms with two or more types reinforcements, i.e., different size particles and fibers, for magnesium-based composites was developed. An advanced and affordable technique of fabricating hybrid magnesium-based composites called the preform-squeeze casting was employed successfully.
2010-04-12
Technical Paper
2010-01-0407
Jafar Albinmousa, Adrian Pascu, Hamid Jahed, M.F. Horstemeyer, Alan Luo, D. Chen, Steve Lambert, J. Jordon, S. Begum, Xuming Su, Q.Q. Duan, Richard Osborne, Z. Zhang, Lin Zhang, T. Luo, Yuansheng Yang
Magnesium alloys are the lightest structural metal and recently attention has been focused on using them for structural automotive components. Fatigue and durability studies are essential in the design of these load-bearing components. In 2006, a large multinational research effort, Magnesium Front End Research & Development (MFERD), was launched involving researchers from Canada, China and the US. The MFERD project is intended to investigate the applicability of Mg alloys as lightweight materials for automotive body structures. The participating institutions in fatigue and durability studies were the University of Waterloo and Ryerson University from Canada, Institute of Metal Research (IMR) from China, and Mississippi State University, Westmorland, General Motors Corporation, Ford Motor Company and Chrysler Group LLC from the United States.
2010-04-12
Technical Paper
2010-01-0410
Alan A. Luo, Joy Forsmark, Xichen Sun, Scott Shook
Magnesium alloy extrusions offer potentially more mass saving compared to magnesium castings. One of the tasks in the United States Automotive Materials Partnership (USAMP) ?Magnesium Front End Research and Development? (MFERD) project is to evaluate magnesium extrusion alloys AM30, AZ31 and AZ61 for automotive body applications. Solid and hollow sections were made by lowcost direct extrusion process. Mechanical properties in tension and compression were tested in extrusion, transverse and 45 degree directions. The tensile properties of the extrusion alloys in the extrusion direction are generally higher than those of conventional die cast alloys. However, significant tension-compression asymmetry and plastic anisotropy need to be understood and captured in the component design.
2010-04-12
Technical Paper
2010-01-0409
John Jekl, Richard D. Berkmortel, Paula Armstrong
The main objective of this paper is to demonstrate how flow and solidification simulation were used in the development of a new gating system design for three different magnesium alloys; and to determine the relative castability of each alloy based on casting trials. Prototype tooling for an existing 3-slide rear wheel drive automatic transmission case designed for aluminum A380 was provided by General Motors. Flow and solidification simulation were performed using Magmasoft on the existing runner system design using A380 (baseline), AE44, MRI153M and MRI230D. Based on the filling results, new designs were developed at Meridian for the magnesium alloys. Subsequent modeling was performed to verify the new design and the changes were incorporated into the prototype tool. Casting trials were conducted with the three magnesium alloys and the relative castability was evaluated.
2010-04-12
Technical Paper
2010-01-0412
Jonathan Robert Burns, Henry Hu, Xueyuan Nie, Lihong Han
Powertrain applications of alloy AJ62 arose from its comparative resistance to high temperature deformation among magnesium alloys. In this research, AJ62 permanent-mould cast in different section thicknesses was subjected to immersion corrosion in commercially-available engine coolant. The objective was to determine corrosion behaviour variation among casting thicknesses. Corrosion product accumulation suggests passive film formation, and unlike in other media, the film exhibits certain stability. Extreme thicknesses were used to generate polarization curves for their respective microstructures in engine coolant. Variation with casting section thickness was observed in the curves. These preliminary results indicate coarsened microstructures reduce corrosion resistance of the permanent mold cast AJ62 alloy.
2010-04-12
Technical Paper
2010-01-0411
Behzad Behravesh, Lei Liu, Hamid Jahed, Stephen Lambert, Grzegorz Glinka, Norman Zhou
Interest in magnesium, as the lightest engineering metal, has increased in the automotive industry as a result of requirements for lighter and cleaner vehicles. Resistance spot welding (RSW) is already the predominant mode of fabrication in this industry, and the fatigue of spot welded magnesium sheet must be studied. In this study, the tensile and fatigue strength of resistance spot welded AZ31 Mg alloy was studied. Three sets of tensile shear spot welded specimens were prepared with different welding parameters to achieve different nugget sizes. Metallographic examination revealed grain size changes from the base material (BM) to heat affected zone (HAZ) to the fusion zone (FZ). Monotonic tensile and fatigue tests were conducted and the effect of nugget size on tensile shear and fatigue strength was discussed.
2010-04-12
Technical Paper
2010-01-0403
Kumar Sadayappan, Michael Vassos
Thixomolding® is a semi-solid metal-molding process used to produce magnesium alloy components. The component quality is claimed to be high due to the low speed non-turbulent filling experienced in the thixomolding process. Parts of AM60 alloy were produced in a USAMP/DOE funded and directed project to demonstrate economic production of quality large thin wall, structural magnesium component using thixomolding. The selected application was the Ford F-150 shotgun; the structural connection between the A-pillar and the radiator support structure, and produced by G-Mag International. Test pieces were assessed through radiography and mechanical testing. The properties of the shot-gun casting were compared to those of experimental plate castings. Properties of the large casting were found to have a higher level of scatter compared to plate castings which can be attributed to the gas entrapment and oxide inclusions. The results are presented and discussed in this publication.
2010-04-12
Journal Article
2010-01-0404
Okechukwu Anopuo, Yuanding Huang, Norbert Hort, Hajo Dieringa, Karl Ulrich Kainer
Understanding the creep and bolt load retention (BLR) behavior of promising Mg-Al alloys are crucial to developing elevated temperature resistance alloys. This is especially true for elevated temperature automotive applications with a prevalence of bolted joints. In this study, creep and fastener clamp load response of Mg-Al alloy AS41 was investigated and compared to that of Mg4Al and AS41 micro-alloyed with 0.15 % Ca. A compliance-creep approach was used to model the response of these Mg-Al alloys at bolted joints. The equation prediction of the BLR response and experimental results are in good agreement. AS41+0.15 Ca shows improved creep and BLR properties up to 175°C. A correlation between the microstructures, creep and BLR results reveal that the formation of a ternary CaMgSi phase is responsible for the improved elevated temperature behavior.
2011-04-12
Technical Paper
2011-01-0429
Mathew Kuttolamadom, Joshua Jones, Laine Mears, John Ziegert, Thomas Kurfess
For incorporating titanium components onto a vehicle in place of existing iron/steel components, there is a need for a methodical procedure to ensure successful and efficient integration. This involves a refinement over standard lightweight engineering procedures. In this paper, a suitable procedure is developed for replacing a structural component with titanium and the method realized. Design and manufacturing issues associated with integrating titanium are identified and addressed. The importance of justifying component replacement in terms of life-cycle costs rather than purely by the manufacturing cost alone is also emphasized.
2011-04-12
Journal Article
2011-01-0470
Pai-Chen Lin, Ru-Yi He, Zheng-Ming Su, Zhi-Long Lin
Failure modes of spot friction welds in cross-tension specimens of aluminum 6061-T6 sheets are first investigated based on experimental observations. Optical and scanning electron micrographs of the welds before and after failure under quasi-static and cyclic loading conditions are examined. Experimental results show that the failure modes of the welds under quasi-static and cyclic loading conditions are quite different. Under quasi-static loading conditions, the failure mainly starts from the necking of the upper sheet outside the weld. Under low-cycle loading conditions, the dominant fatigue cracks are the kinked cracks growing into the upper sheet from the crack tips; hence, the upper nugget pullout failure mode can be seen. Under high-cycle loading conditions, the dominant fatigue cracks are kinked cracks growing into the lower sheet from the crack tips; subsequently, the lower nugget pullout failure mode can be seen.
2010-04-12
Journal Article
2010-01-0655
Greg Wallace, Andrew P. Jackson, Stephen P. Midson
A turbocharger essentially consists of a turbine and an impeller wheel connected on a common shaft. The turbocharger converts waste energy from the exhaust into compressed air, which is pushed into an engine to produce more power and torque, as well as improving the overall efficiency of the combustion process. The compression ratio for modern diesel engines can be up to 5:1, which can be only achieved using a complex impeller design and very high rotation speeds (up to 150,000 rpm for small impellers). The complex geometry and very high running speeds of impellers creates high stresses at locations such as blade roots and around the bore, and so impellers normally fail from fatigue. Therefore, it is vital to minimize defects while fabricating turbocharger impellers. Current methods for producing aluminum turbocharger impellers are plaster casting or by forging + machining. However, both of these current methods have serious drawbacks.
2010-04-12
Journal Article
2010-01-0657
William (Jud) Dunlap, Alan Druschitz
Exhaust manifolds and turbocharger housings require good elevated temperature strength, good resistance to thermal fatigue and a stable microstructure. High silicon ductile iron, high silicon-molybdenum ductile iron and Ni-resist (a high nickel ductile iron) are the cast materials of choice. Unfortunately, molybdenum and nickel are expensive. In this study, a lower cost, high silicon-titanium, compacted graphite iron was developed and compared to high silicon ductile iron and higher cost, high silicon-molybdenum ductile iron. Room and elevated temperature strength data is presented.
2010-04-12
Journal Article
2010-01-0652
Christopher A. Bixler, Kathy L. Hayrynen, John Keough, George Pfaffmann, Scott Gledhill
There are numerous component applications that would benefit from localized austempering (heat treating only a portion of the component) for either improved wear properties or fatigue strength. Currently available methods for “surface austempering” of ductile iron are often expensive and not as well controlled as would be desired. This study was undertaken to find a better process. Locally Austempered Ductile Iron (LADI) is the result of those efforts. LADI is a surface hardening heat treatment process that will produce a localized case depth of an ausferrite microstructure (ADI) in a desired area of a component. This process has been jointly developed by Ajax Tocco Magnethermic Corporation (ATM) and Applied Process, Inc.- Technologies Division (AP) with support and collaboration from ThyssenKrupp Waupaca, Inc. (TKW). This paper describes the outcome of using this patent pending process (US #65/195,131).
2010-04-12
Journal Article
2010-01-0654
Delin Li, Clayton Sloss
There is a wide spectrum of cast ferrous heat resistant alloys available for exhaust component applications such as exhaust manifolds and turbocharger housings. Generally speaking, the ferrous alloys can be divided into four groups including: ferritic cast irons, austenitic cast irons, ferritic stainless steels, and austenitic stainless steels. Selection of a suitable alloy usually depends on a number of material properties meeting the requirements of a specific application. Ferritic cast irons continue to be an important alloy for exhaust manifolds and turbocharger housings due to their relatively low cost. A better understanding of the alloying effects and graphite morphologies of ferritic cast irons are discussed and their effect on material behavior such as the brittleness at medium temperatures is provided. The nickel-alloyed austenitic cast irons, also known as Ni-resist, exhibit stable structure and improved high-temperature strength compared to the ferritic cast irons.
2011-04-12
Technical Paper
2011-01-0235
Fadi Abu-Farha, Louis Hector, Paul Krajewski
Forming Limit Curves (FLCs) were developed for the 5083 aluminum alloy at conditions simulating high temperature processes such as superplastic and quick plastic forming. Sheet samples were formed at 450 °C and at a constant strain rate of 5x10-3 s-1, by free bulging into a set of elliptical die inserts with different aspect ratios. Friction-independent formability diagrams, which distinguish between the safe and unsafe deformation zones, were constructed. Although the formability diagrams were confined to the biaxial strain region (right side quadrant of an FLD), the elliptical die insert methodology provides formability maps under conditions where traditional mechanical stretching techniques are limited.
2011-04-12
Journal Article
2011-01-0193
Qigui Wang, Peggy Jones
Cast aluminum alloys are increasingly used in cyclically loaded automotive structural applications for light weight and fuel economy. The fatigue resistance of aluminum castings strongly depends upon the presence of casting flaws and characteristics of microstructural constituents. The existence of casting flaws significantly reduces fatigue crack initiation life. In the absence of casting flaws, however, crack initiation occurs at the fatigue-sensitive microstructural constituents. Cracking and debonding of large silicon (Si) and Fe-rich intermetallic particles and crystallographic shearing from persistent slip bands in the aluminum matrix play an important role in crack initiation. This paper presents fatigue life models for aluminum castings free of casting flaws, which complement the fatigue life models for aluminum castings containing casting flaws published in [1].
2011-04-12
Journal Article
2011-01-0528
Qigui Wang, Yucong Wang
There is an increasing demand in automated manufacturability analysis of metal castings at the initial stages of their design. This paper presents a system developed for virtual manufacturability analysis of casting components. The system can be used by a casting designer to evaluate manufacturability of a part designed for various manufacture processes including casting, heat treatment, and machining. The system uses computational geometrics and geometric reasoning to extract manufacturing features and geometry characteristics from a part CAD model. It uses an expert system and a design database consisting of metal casting, heat treatment and machining process knowledge and rules to present manufacturability analysis results and advice to the designer. Application of the system is demonstrated for the manufacturability assessment of automotive cast aluminum components.
2011-04-12
Journal Article
2011-01-0535
L. Rafael Sanchez PhD, Susan Hartfield-Wunsch
During sheet metal forming, the friction and surface roughness change as the sheet slides, bends and stretches against the tools. This study assessed evolution of friction and surface roughness changes on aluminum sheet with two surface finish conditions, mill finish (MF) and electron discharge texture (EDT), in both the longitudinal and the transverse rolling directions of the sheet. The sheets were tested using a three pin Draw Bead Simulator (DBS). Surface roughness of the sheet evolved as a result of bending at the first shoulder, reverse bending at the middle pin, bending at the second shoulder and unbending at the exit. Stretching conditions and sheet-pin contact were also varied to see the impact on surface roughness. In general, the largest surface roughness change for the transverse direction was observed at the convex side of the exit shoulder pin and on the convex side of the first shoulder for the longitudinal direction.
2011-04-12
Journal Article
2011-01-0534
Susan E. Hartfield-Wunsch, Donald Cohen, L. Rafael sanchez PhD, Lars-Erik Brattstrom
Aluminum sheet is commercially available in three surface finishes, mill finish (MF), electric discharge texture (EDT), and dull finish (DF). This surface finish impacts the friction behavior during sheet metal forming. A study was done to compare ten commercially available sheet samples from several suppliers. The friction behavior was characterized in the longitudinal and transverse directions using a Draw Bead Simulator (DBS) test, resulting in a coefficient of friction (COF) value for each material. Characterization of the friction behavior in each direction provides useful data for formability analysis. To quantitatively characterize the surface finish, three-dimensional MicroTexture measurements were done with a WYKO NT8000 instrument. In general, the MF samples have the smoothest surface, with Sa values of 0.20-0.30 μm and the lowest COF values. The EDT samples have the roughest surface, with Sa values of 0.60-1.00 μm, and the highest COF values.
2011-04-12
Journal Article
2011-01-0533
Susan E. Hartfield-Wunsch, Jamie Burdeski, Elgin Miller, Wei Ji
It is important to understand the accuracy level of the formability analysis for any new process so that correct predictions can be made in product and die design. This report focuses on the formability analysis methodology developed for the preform anneal process. In this process, the aluminum panel is partially formed, annealed to eliminate the cold work from the first step, and then formed to the final shape using the same die. This process has the ability to form more complex parts than conventional aluminum stamping, and has been demonstrated on a complex one-piece door inner and a complex one-piece liftgate inner with AA5182-O3. Both panels only required slight design modifications to the original steel product geometry. This report focuses on the formability analysis correlation with physical panels for the liftgate inner, considering both full panel anneal in a convection oven and local annealing of critical areas.
2011-04-12
Journal Article
2011-01-0477
Sri Lathabai, Vinay Tyagi, David Ritchie, Trevor Kearney, Barrie Finnin, Shane Christian, Andrew Sansome, Gary White
Friction stir blind riveting (FSBR) is a new process for joining automotive light alloys based on aluminium and magnesium. During FSBR, a blind rivet, rotating at high speed (typically 2000-12000 rpm), is brought in contact with the upper sheet or workpiece of a lap joint. The frictional heat generated between the rivet and the workpieces softens the material and this, in turn, reduces the force required to drive the rivet into the workpieces. Once fully inserted, the blind rivet is upset using the internal mandrel and an appropriate tool, as in conventional blind riveting. The FSBR process thus retains the one-sided accessibility of conventional blind riveting, but eliminates the extra predrilling and any subsequent cleaning steps required for the latter process.
2013-04-08
Technical Paper
2013-01-1153
Alexandre Bellegard Farina, Rodrigo César N. Liberto, Celso Antonio Barbosa
UNS N07751 and UNS N07080 alloys are commonly applied for automotive valve production for high performance internal combustion engines. These alloys present high hot resistance to mechanical strength, oxidation, corrosion, creep and microstructural stability. However, these alloys present low wear resistance and high cost due to the high nickel contents. In this work it is presented the development of two new nickel intermediate alloys for application in automotive high performance valves that are alternatives to the alloys UNS N07751 and UNS N07080. The new developed alloys are based on a high nickel chromium austenitic matrix with dispersion of γ' and γ'' phases and containing different NbC contents.
2013-04-08
Technical Paper
2013-01-1154
Thomas Cornelio, Michael R. Schloder, Michael O'Neill, Stephen Bowyer, Gary Vrsek
As a result of the wide range of operating environments, component parts of automotive and commercial engine exhaust systems require a unique combination of material properties that are not easily met using existing wrought, cast, or powder metallurgy alloys. Alpha Sintered Metals (ASM) now offers a new Powder Metal (PM) alloy with improved hot oxidation properties that not only supplements the application of traditional stainless steel alloys but also enhances the service life reliability of these components for elevated exhaust temperature applications. ASM's new alloy named Alphaloy, demonstrates material property advantages for several critical exhaust system attributes. The test results of studies comparing Alphaloy to other traditional materials exhibit improved performance relative to hot oxidation resistance, tensile strength and machinability while maintaining consistent performance for thermal expansion, atmospheric corrosion and weldability.
2013-04-08
Technical Paper
2013-01-1170
Nia R. Harrison, Andrey Ilinich, Peter A. Friedman, Jugraj Singh, Ravi Verma
Traditional warm forming of aluminum refers to sheet forming in the temperature range of 200°C to 350°C using heated, matched die sets similar to conventional stamping. While the benefits of this process can include design freedom, improved dimensional capability and potentially reduced cycle times, the process is complex and requires expensive, heated dies. The objective of this work was to develop a warm forming process that both retains the benefits of traditional warm forming while allowing for the use of lower-cost tooling. Enhanced formability characteristics of aluminum sheet have been observed when there is a prescribed temperature difference between the die and the sheet; often referred to as a non-isothermal condition. This work, which was supported by the USCAR-AMD initiative, demonstrated the benefits of the non-isothermal warm forming approach on a full-scale door inner panel. Finite element analysis was used to guide the design of the die face and blank shape.
2013-04-08
Journal Article
2013-01-1024
Pai-Chen Lin, Zheng-Ming Su, Wei-Jen Lai, Jwo Pan
Fatigue behavior of self-piercing rivets (SPRs) and clinch joints in lap-shear specimens of 6111-T4 aluminum sheets is investigated based on experimental observations and a fatigue life estimation model. Lap-shear specimens with SRPs and clinch joints were tested under cyclic loading conditions. Under cyclic loading conditions, fatigue cracks start from the curved interfacial surface of the upper sheet and then grow into the upper sheet thickness for both self-piercing rivets and clinch joints. The self-piercing rivets and clinch joints fail finally through the circumferential/transverse crack growth in the upper sheets and inner button crack growth, respectively. The structural stress solution and the experimental stress-life data for aluminum 6111-T4 sheets are adopted to estimate the fatigue lives of both types of joints. The fatigue life estimations based on the structural stress model show good agreement with the experimental results.
2013-04-08
Journal Article
2013-01-1020
Wei-Jen Lai, Jwo Pan, Zhili Feng, Michael Santella, Tsung-Yu Pan
Failure modes and fatigue behaviors of ultrasonic spot welds in lap-shear specimens of magnesium AZ31B-H24 and hot-dipped-galvanized mild steel sheets with and without adhesive are investigated. Ultrasonic spot welded, adhesive-bonded, and weld-bonded lap-shear specimens were made. These lap-shear specimens were tested under quasi-static and cyclic loading conditions. The ultrasonic spot weld appears not to provide extra strength to the weld-bonded lap-shear specimen under quasi-static and cyclic loading conditions. The quasi-static and fatigue strengths of adhesive-bonded and weld-bonded lap-shear specimens appear to be the same. For the ultrasonic spot welded lap-shear specimens, the optical micrographs indicate that failure mode changes from the partial nugget pullout mode under quasi-static and low-cycle loading conditions to the kinked crack growth mode under high-cycle loading conditions.
2013-04-08
Journal Article
2013-01-1017
Tsung-Yu Pan, Zhili Feng, Michael Santella, Jian Chen
Development of reliable magnesium (Mg) to steel joining methods is one of the critical issues in broader applications of Mg in automotive body construction. Ultrasonic spot welding (USW) has been demonstrated successfully to join Mg to steel and to achieve strong joints. In this study, corrosion test of ultrasonic spot welds between 1.6 mm thick Mg AZ31B-H24 and 0.8 mm thick galvanized mild steel, without and with adhesive, was conducted. Adhesive used was a one-component, heat-cured epoxy material, and was applied between overlapped sheets before USW. Corrosion test was conducted with an automotive cyclic corrosion test, which includes cyclic exposures of dipping in the 0.5% sodium chloride (NaCl) bath, a constant humidity environment, and a drying period. Lap shear strength of the joints decreased with the cycles of corrosion exposure. Good joint strengths were retained at the end of 30-cycle test.
2004-03-08
Technical Paper
2004-01-0133
Wenyue Zheng, C. Derushie, R. Zhang, J. Lo
Magnesium alloys, with the highest strength-to-weight ratio of the common engineering alloys, have been used in castings of various automotive components. The forecast trend for the use of the metal in automobiles suggests a more rapid growth pace in the coming decade. However, Mg alloys happen to be among the most reactive materials in natural environments, such as those applicable to the exterior automotive conditions. The most challenging form of corrosion is galvanic corrosion: the corrosion of Mg parts when in contact with other materials such as coated steel bolts and nuts. In the joining areas, crevice corrosion can also be a concern. Effective coatings are essential for such applications.
2004-03-08
Technical Paper
2004-01-0137
S. E. LeBeau, M. W. Walukas, R. F. Decker, Pierre LaBelle, A. R. Moore, J. W. Jones
Automotive manufacturers are continually pushing for reduced cost, increased fuel economy, lower emissions and improved performance. Magnesium is the lightest structural metal and has therefore enjoyed a double-digit annual growth in automotive applications since 1990, aimed at reducing vehicle platform weights to increase fuel economy. Nevertheless the progress of magnesium as an alternative lightweight structural material (compared to aluminum, engineered plastics and high alloy steels) is being impeded by the lack of published alloy properties and general knowledge of the material. Thixomat, Inc. is conducting independent fundamental studies to measure the influence of Thixomolding® process parameters on a variety of physical and mechanical properties for injection molded magnesium alloys. Determination of conventional mechanical properties are being complemented with fatigue behavior studies using new ultrasonic fatigue instrumentation at the University of Michigan.
Viewing 1 to 30 of 1821

Filter

  • Range:
    to:
  • Year: