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Viewing 121 to 150 of 36593
1990-02-01
Technical Paper
900728
Gary P. McKittrick
In order to more fully explain variations in the performance of instrument panel (IP) structural attachment bosses of molded plastic, computerized mold filling analysis was performed on a mold cavity and its melt distribution system (manifold, drops, runners and gates). A comparison of the simulated filling pattern with measured boss stripping torques showed a correlation between boss quality and the conditions experienced by the melt during the molding process. By optimizing the diameters of various flow channels in the mold, an improvement in the quality of certain “problem” bosses is anticipated. Balancing of the filling pattern to improve boss performance is also expected to enhance the processability of the mold. Recommendations which resulted from this study are currently being implemented to quantify benefits and substantiate conclusions.
1990-02-01
Technical Paper
900738
David Dickinson, Chon-Liang Tsai, Oussama Jammal
The weld nugget in resistance spot welding of stainless 347 steel was found, using the finite element method, initiating at a distance from the electrode center in a ring shape. The ring-like weld nugget expands inwards and outwards during the welding cycles. The welding current, electrode pressure and hold time affected the thermomechanical interactions of the welding process and changed the final nugget geometry. As a result of spot welding of unequal thickness workpieces, the weld nugget formed mostly in the thicker workpiece than in the thinner workpiece. When spot welding dissimilar materials, the weld nugget formed more in the workpiece of lower thermal conductivity or higher electrical resistivity.
1990-02-01
Technical Paper
900734
John T. Russell
This paper proposes and discusses criteria for determining whether or not a test is useful in fulfilling its intended purpose. Distinctions are drawn between those criteria which are desirable but not absolutely necessary and those which are essential to a useful test. Key criteria include correlation of test results to performance characteristics, applicability to a wide range of products, discrimination between different products, and sufficient precision and accuracy. In addition, some of the basic philosophy behind test method development and the compromises necessary in that process are discussed.
1990-02-01
Technical Paper
900721
Edward C. Chiang, George P. C. Huang, Zintai Chang, John H. Johnson
Engineers have found that the one-dimensional approach to compressible flows in ducts is extremely informative and effective. This paper extends these methods to cooling airflow for engine cooling system that they may be used to understand and estimate the behavior of cooling air flow in a complex duct system.
1990-02-01
Technical Paper
900724
Ralph L. Webb, Paul A. Farrell
This paper describes improvements in the design of conventional copper-brass radiators that should provide increased thermal performance, durability, and reduced material cost. A 1-row, and an improved 2-row design is described that has lower air and coolant pressure drop, and lower material costs than a conventional multi-row design. A parametric study describes how changes in core geometry affect thermal and pressure drop performance, and core weight. Several mechanical design improvements are identified, which reduce stress in the radiator tube-header joint. Design equations supporting the design recommendations are also given or referenced. Work in progress leading to reduced fin corrosion is also reviewed.
1990-02-01
Technical Paper
900722
Ralph L. Webb
A flow visualization study of the louvered fin geometry, commonly used in automotive heat exchangers was performed. Flow visualization was performed using a dye injection technique with 10:1 scale models. The geometrical parameters, louver pitch, louver angle, and fin pitch were varied to determine their effect on the flow structure. Tests covered louver pitch based Reynolds numbers of 400 - 4000. Data are presented in the form of a dimensionless flow efficiency (defined in terms of the mean flow angle, relative to the louver angle) and Reynolds number. Correlations are developed to predict the flow efficiency as a function of dimensionless geometrical groups and Reynolds number. A discussion of the flow structure is also presented.
1990-02-01
Technical Paper
900716
C. L. Alaniz, L. E. Brookes, T. N. Seel
The stiffness of an automobile body panel is significant to structural performance as well as customer perception. Body panel stiffness can be predicted with limited accuracy using spherical shell theory, empirical methods and linear elastic finite element codes. This paper describes a study to confirm that body panel stiffness can be accurately predicted by non-linear finite element analysis. Specifically, the stiffnesses of two sets of 8 simple bispherically curved test panels with curvature and thickness differences were experimentally measured and correlated to ABAQUS non-linear finite element plots. It was concluded that increased accuracy in body panel stiffness predictions can be obtained with non-linear finite element analysis techniques.
1990-04-01
Technical Paper
900928
John Suchyta
Abstract Microcontrollers (MCUs) are found in all types of vehicle electronics, from powertrain control to interior features. The microcontroller suppliers who are successful in the vehicle electronics industry know that quality must be designed into their products and processes. The quality of the final product is just as dependent on the design of the software as it is on the design of the hardware. How does the design of the microcontroller affect the task of the software engineer in developing quality software? Microcontroller design considerations to assure quality start with the processor architecture and the peripheral functions which the MCU must perform, and extend to processing, packaging, and testing. Motorola microcontroller architectures and peripheral functions are examined to show how designed-in quality reduces the risk of error for the software engineer developing code.
1990-04-01
Technical Paper
900927
Ralph E. Johnson
Abstract One of the best ways to improve the quality and reduce the cost of software is to increase software reuse. One of the best technologies for increasing software reuse is object-oriented programming. Languages like C++ are making object-oriented programming accessible to more people, but many do not realize the impact that increasing reuse can have on the software development process. Reusable software is easy to use, but hard to produce. Object-oriented programming decreases the time spent coding and debugging, but increases the proportion of time spent designing. Object-oriented programming can have a big pay-off, but like all new technologies it has costs and risks, and the most successful uses of object-oriented programming are by those who are aware of the potential problems.
1990-04-01
Technical Paper
900923
M. Joseph King, Paul K. Erickson
Abstract Along with the many benefits of 3-D CAD systems there are also problems. One problem is that multiple uses of a part require redundant work to keep layouts current. Multiple uses result from using the same part in different assemblies or the same assembly in different configurations. Existing CAD products offer solutions which do not address issues like version control adequately. A set of computer programs has been developed to reduce this redundant work. They allow the engineer or designer to change component geometry in one CAD model and have that change reflected in all usages of the part while maintaining version control.
1990-04-01
Technical Paper
900926
Simon M. Kaplan, Alan M. Carroll
Abstract How shall we improve the quality and reliability of the software we produce? We believe that the critical factor is an understanding how software is constructed, and why it is constructed in that way. Once something is understood, we can begin to build better tools to support and mold the process. This paper outlines a view of how the software process proceeds, why it proceeds that way, and how we can use this perspective to build better tools.
1990-04-01
Technical Paper
900917
Hugh C. Morris
This paper presents a response to the question: Simulation - mathematical manipulation or useful design tool? A mathematical model of a modulating valve in a transmission control system was developed to predict clutch pressure modulation characteristics. The transmission control system was previously reported in SAE Paper 850783 - “Electronic/Hydraulic Transmission Control System for Off-Highway Vehicles”. The comparison of simulation predictions with test data illustrates the effectiveness of simulation as a design tool. THE EVOLUTION OF COMPUTER hardware and simulation software has resulted in increased interest and usage of simulation for dynamic analysis of hydraulic systems. Most commercially available software is relatively easy to learn to use. The application of such software and the modeling techniques involved require a longer learning curve.
1990-04-01
Technical Paper
900908
Jason R. Lemon
Concurrent Product and Process Development (CP/PD) is a disciplined computer integrated product and manufacturing process development methodology. CP/PD combines marketing, finance, design, engineering, manufacturing, purchasing and suppliers in the development process from concept initiation to customer delivery.
1990-04-01
Technical Paper
900904
Edward C. Chiang, John R. Keller
When the low-flow engine cooling system was developed, besides the addition of a two-pass radiator, another important design change was the replacement of the conventional single valve thermostat with a dual-valve thermostat. This new thermostat was believed to offer better control of coolant temperatures and provide better engine cooling system responses. The present study is to understand the thermal characters of the dual-valve thermostat and its effect on the performance of a low-flow engine cooling system. By developing a computational thermostat model for use with the VECSS Simulation Code, several computational experiments were conducted to compare the dynamic performance of a low-flow cooling system fitted with different thermostats.
1990-04-01
Technical Paper
900912
Sridhar Thyageswaran, Francisco Ruiz
The regenerative engine cycle, in which part of the thermal energy of the exhaust gases is stored internally, for use in the following engine cycle, is analyzed as a function of time and several design parameters: compression ratio, regeneration timing, equivalence ratio, regenerator design Reynolds number and engine speed. The effects of fluid friction and heat transfer in the regenerator are taken into account in the model. Calculations show that the regenerative engine maintains a substantial efficiency advantage over the conventional Otto cycle, even after fluid friction losses. The effects of the different design parameters are pointed out, as well as ways to optimize the performance of a regenerative engine.
1990-04-01
Technical Paper
900888
Harold W. Hill
The 621 is the first of the new Case “21 Series” Wheel Loaders. At 116 net horsepower and with bucket capacities of 2.00 to 2.75 cubic yards, it features a cab located on the rear mainframe and a z-bar loader linkage. The 621 is the culmination of a customer-based development program and is representative of J I Case Company's continuing focus on productivity and durability in its products. It was designed with the operator in mind, thoroughly considering ergonomics and visibility. The 621's loader and vehicle performance, dynamic stability and responsive steering lead to short cycle times and high productivity. The product development cycle of the 621 was reduced to two-and-one-half years through the application of simultaneous engineering and manufacturing concepts. As a result of an extensive, statistics-based field and laboratory demonstration test program, the 621 offers improved reliability over its predecessor, the W20C.
1990-04-01
Technical Paper
900890
A. A. Shabana
In this paper methods for the nonlinear dynamic analysis of multibody vehicle systems are presented. A total Lagrangian finite element formulation for deformable bodies of the vehicle systems that undergo large translational and rotational displacements is developed. A set of nonlinear dynamic differential equations are developed in a closed form for each finite element in terms of the reference as well as the nodal elstic coordinates and their time derivatives. These equations are expressed in terms of a set of element invariants that depend on the assumed displacement field. The invariants of the deformable body that undergoes large reference translational and rotational displacements can be obtained by assembling the invariants of its elements using a standard finite element procedure. The nonlinear dynamic equations of the deformable body can then be obtained by assembling the nonlinear element equations.
1990-04-01
Technical Paper
900886
David N. Philipps, Charles J. Hunckler
Mesh sizes of finite element models are typically based on an engineers past experience. A better method might be an automated mesh refinement based on reducing the solution error to an acceptable level. The procedure would be to analyze a rough model, determine where the maximum solution erros are occurring and refine the model in those regions. The ANSYS finite element program was used to apply this automated technique to typical structural components.
1990-04-01
Technical Paper
900892
R. Natarajan
Literature search reveals that for design of saddle supported pressure vessels there are no codified design procedures analogous to Zick's analysis. Thus a detailed study of the pressure vessel in terms of stress distribution in the cylindrical vessel and in the vicinity of the saddle-vessel intersection will lead to an alternate design procedure. A finite element code has thus been developed which will pave way in achieving this goal. Finite element analyses have been performed on several geometries of the vessel under different loading conditions and the results presented in this paper.
1990-04-01
Technical Paper
900877
John L. Rowland
Throughout the entire life of a product, establishing and improving product quality are dependent upon clear, accurate data, strong participation by all included disciplines and strong basic systems to provide the proper feedback at the proper time. The ongoing improvement of product quality and reliability is a key element to the survival of any manufacturing organization in today's marketplace. In the electronics market, the ever accelerating pace of technological development places additional emphasis upon methodical analysis and disciplined execution of product development and release to guard against the potential design and manufacturing errors or oversights which could result in interruptions in manufacturing flow or latent product defects. The customer-supplier relationship setting for this paper is the “build to specification” scenario.
1990-04-01
Technical Paper
900879
Thomas J. Mueller
Abstract Stereolithography has emerged as a means of quickly creating model and prototype parts without tooling and is becoming a tool designers can use to get products to market faster, reduce development costs, and improve product quality. Applications of stereolithography in the development of injection molded, investment cast, sand cast, and NC machined parts will be covered. In the last several years, a number of market factors have begun to significantly change the nature of product development. Continuing improvements in technology have resulted in significantly shorter product life cycles, requiring that new products get to market in a timely manner. Improved product quality has ceased to be a sales feature and has become instead a minimum requirement to compete in the marketplace. Selling prices have experienced downward pressure from both domestic and foreign competitors.
1990-04-01
Technical Paper
900878
Steve Colburn
A computer solid modeling based system is described that is used for the numerical control machining of foundry patterns and forging dies. Key elements of the system include support of parametric modeling, a new global blending process to form the fillets and rounds required by these manufacturing processes and the automatic generation of numerical control tool path programs. These elements of the system are described and compared to existing methods. Use of the system is illustrated by an example forge die application.
1990-04-01
Technical Paper
900876
James A. Mosier
Abstract Adaptive control, based on modeling of a manufacturing process and coupled with predictive control methods, allows for adjustment of nonrobust process variables while maintaining the ability to statistically monitor the cause system for unexpected change. This strategy recognizes both the need for continual improvement in process operation and the need to face the reality of current process under-standing and practical commercial considerations. It incorporates both active and passive use of statistical methods for improving the quality of process output while retaining the ability to detect new process changes. A final feature is the opportunity to refine engineering knowledge concerning process interaction and the adaptive decision model.
1990-04-01
Technical Paper
900875
James L. McCollough
One of the key elements of response by many companies to the competitive environment is significant investments in new products. This increased competitive environment has been most influenced by international competition. Striving for “world class” products has to evolve if U.S. companies are to survive in the 1990s and beyond. While many large U.S. companies excel in basic research, with few exceptions they have had less than positive results in turning that advantage into a competitive edge as they introduce new products in the world marketplace. We cannot continue to believe that being first with a new technology is enough to enable us to thwart competition. Speed to market is extremely critical, as is the challenge of producing world class quality. Add to this the desire to recover our return on investment quickly.
1990-02-01
Technical Paper
900843
E. C. Mikulcik, L. G. Jensen
ABSTRACT
1990-02-01
Technical Paper
900850
Mark D. Hemingway
Technology has progressed from strip charts to computerized acquisition systems. Unfortunately, even with the advanced computational equipment available we still convert the data into “strip chart” graphs (time dependent representation). Perhaps a better way to analyze a complex system such as an automobile would be to graphically represent various parameters and their relationship to each other. Most engine calibrations are presented in this fashion. This paper presents a system to acquire, compactly store, analyze and report data in a relational manner for modeling, trouble shooting, and calibration.
1990-02-01
Technical Paper
900835
Tsugio Ikeda, Katsutoshi Iwamoto, Tsuyoshi Sato
Plastic composites are increasingly applied to automotive mechanical parts which demand high strength and high stiffness to meet cost saving and weight reduction. However, plastic component design and molding have often involved a process of trial and error. Recent progress in numerical analysis, including the use of the FEM (Finite Element Method), has made it possible to obtain quantitative data on part deformation and in-mold material flow and to optimize mold geometries. This paper first describes a developemental process of an injection molded accelerator pedal made from glass fiber reinforced thermoplastics (Polyamide: PA, Polypropylene: PP). This process consists of an integrated CAE (Computer Aided Engineering) system which can be applied both to component and mold optimized design. (Fig.1 shows) This paper also discusses the effects of ribbed structure (Type I ∼ III) and the number of molding gates on parts.
1990-02-01
Technical Paper
900840
Edward A. Bass, Larry M. Bendele, Scott T. McBroom
Forty-five cars were entered from 37 universities across the U.S. and Canada in the ninth annual Formula SAE Student Design Competition held on May 25, 26 and 27 at the University of Texas at San Antonio (UTSA). Thirty-six cars from 31 schools actually competed, but only 22 cars finished. The event included many firsts in Formula SAE. The SAE South Texas Section set a precedent by co-hosting the competition with the UTSA. The GM Sunraycer display and demonstration exhibited high technology and corporate support of Formula SAE. Total award funds (from various sponsors) exceeded those of previous events. New awards were given by new sponsors in 1989.
1990-02-01
Technical Paper
900830
Kyung K. Choi, Jong Sang Park
A unified continuum formulation for design sensitivity analysis of critical loads is developed for nonlinear structural systems that are subjected to conservative loading. Sizing design variables such as cross-sectional areas of beam or truss design components and thicknesses of plate or membrane design components are included in development of the continuum design sensitivity analysis method. For nonlinear structural analysis, both geometric and material nonlinear effects are considered. The total Lagrangian formulations for incremental equilibrium analysis and one-point linear eigenvalue problems for stability analysis are utilized. Numerical methods are presented to evaluate design sensitivity expressions, using structural analysis results from established finite element codes. For design sensitivity of the estimated critical load, a continuum design sensitivity analysis method is developed using the lowest eigenvalue of the linear eigenvalue problem.
1990-02-01
Technical Paper
900832
Mohamed E. M. El-Sayed, Elizabeth H. Lund
Abstract This paper presents a nominal stress approach to the optimum design of structures for fatigue life requirement. The basic concept is to use the load history data, the nominal stresses of the structure and the material fatigue properties to calculate the fatigue life during the optimization process. The optimization task with fatigue life constraints and the fatigue life calculation are discussed. The life requirement is considered as side constraint and the structure weight as the objective function. The approach developed yields good results, for the design optimization of the SAE keyhole specimen, using the fatigue test data of different load histories.
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