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Technical Paper

Errors in the Driveline System Balancing Process

2001-04-30
2001-01-1504
Single-plane balancing is a very well-understood process, whereby an imbalance vector is determined and then opposed by a similar vector of equal magnitude but 180° out of phase. This is used in many situations to improve machine performance, vibration, noise etc. However, there is inherent in this process a sensitivity to errors of measurement and correction, since a large imbalance vector and the equally large correction vector must be of exactly equal magnitude and exactly 180° apart for perfect balance. This paper examines the effect of errors in measurement of the initial imbalance and correction of it on the residual balance of automotive drivelines. In particular, it examines the effects of the errors present in a system whereby a system balance correction is made, on a driveline assembly, at discrete points around a given plane (at bolt locations). Errors occur in measurement of vibration, in calculating correction masses and in applying those correction masses.
Technical Paper

Experimental Determination of Automotive System Response Characteristics

2001-04-30
2001-01-1477
Vehicle NVH performance is significantly affected by the dynamics of various primary systems. In the automotive industry, different design activities or vendors are responsible for designing various different systems simultaneously. Therefore, it is highly desirable to gain a better understanding of the individual system characteristics and the interaction between the primary systems to achieve a desirable overall NVH performance. Unfortunately, it is usually quite difficult to construct a proper fixture to accurately measure and quantify the actual uncoupled system characteristics. This paper examines an alternate approach of applying the FRF-based substructuring method to back-calculate the system response characteristics from the full vehicle system measurements. The results are then used to forward-compute the dynamic response of the vehicle, which are also validated by comparison to the direct response function measurements.
Technical Paper

Experimental Study of Automotive Heat Shield Geometry with Natural Convection and Radiation Boundary Conditions

2001-05-14
2001-01-1746
Shielding a vehicle underbody is becoming a daunting task with increased exhaust temperatures due to emissions regulations and ever-increasing packaging constraints, which place components ever closer to exhaust systems. This experimental study was initiated to evaluate the two dimensional thermal effects of heat shield flange height and shield width in vehicle underbody idle conditions. The ultimate goal of this study is to develop a function to optimize the shape of heat shielding to achieve a specified floorpan temperature during vehicle idle conditions.
Technical Paper

The Effects of Front Suspension Parameters on Road Wheel Toe Dynamics

2001-03-05
2001-01-0482
Front road wheel toe dynamics directly affects tire wear and steering wheel vibration, which in turn negatively impacts customer satisfaction. Though static toe can be preset in assembly plants, the front road wheels can vibrate around steering axes or kingpin axes due to tire mass unbalance and nonuniformity. The frequency of the vibration depends on the wheel size and vehicle speed, while the amplitude of the vibration is not only dictated by the tire forces, but also by suspension and steering parameters. This paper presents a study on the sensitivities of the front road wheel toe dynamics to the parameters of a short-long-arm suspension (SLA) and a parallelogram steering system. These parameters includes hard point shift, steering gear compliance, gear friction, control arm bushing rates, friction in control arm ball joints, and compliance in tie rod outboard joints.
Technical Paper

Spot Weld Failure Loads under Combined Mode Loading Conditions

2001-03-05
2001-01-0428
Failure loads of spot welds are investigated under static and impact loading conditions. A test fixture was designed and used to obtain maximum loads of spot welds under a range of combined opening and shear loads with different loading rates. Optical micrographs of the cross sections of spot welds before and after failure were obtained to understand the failure processes under various loading rates and different combinations of loads. The experimental results indicate that under nearly pure opening loads, the failure occurs along the nugget circumferential boundary. Under combined opening and shear loading conditions, the failure starts from the tensile side of the base metal near the nugget in a necking/shear failure mode. The effects of sheet thickness and combined load on the load carrying behavior of spot welds are investigated under static and impact loading conditions based on the experimental results.
Technical Paper

The Effect of High Mileage Spot Weld Degradation on Vehicle Body Joint Stiffness

2001-03-05
2001-01-0426
Joint stiffness is a major contributor to the vehicle body overall bending and torsional stiffness which in turn affects the vehicle NVH performance. Each joint consists of spot welds which function as load paths between adjacent sheet metal. Spot welds tend to lose structural integrity as a result of fatigue, loosening, aging, wear and corrosion of parts as a vehicle accumulates mileage. Experimental methods are used to identify potential degradation mechanisms associated with a spot weld. A CAE model which simulates a vehicle body joint generically is used to determine the effects of each individual degradation mode of a spot weld on joint stiffness. A real life B-pillar to roof joint CAE model of a production vehicle is then employed to examine the significance of weld distribution on joint stiffness degradation. The knowledge derived from this study can be used as a guidance in designing vehicle body structures with respect to spot weld distribution.
Technical Paper

Frequency Response Assurance Criterion and Applications to Model Correlation of Body Structures

2003-05-05
2003-01-1737
Frequency response functions are frequently used production development to identify correlation levels between designs or between analytical simulation and tests. Frequency Response Assurance Criterion is one effective method to quantify such correlations. However, practical issues such as a large number of FRFs exist and complicated modal characteristics often prevent us using the traditional FRAC analysis. A Group FRAC method was developed and is introduced in this article to resolve these application difficulties. This Group FRAC method enables automatic and efficient processing of large number of FRFs in additional to other improvements. The benefit of using the Group FRAC is evidenced through practical applications.
Technical Paper

Drawbeads in Sheet Metal Stamping - A Review

1997-02-24
970986
The paper reviews the role of drawbeads in sheet metal stamping. The design of drawbeads is discussed in depth, with treatment of different bead cross sections, bead end shapes, and bead materials. International standards and practices are included. This is followed by the historical development of the modeling of the drawbead restraining force, starting with basic equilibrium approaches, and leading to the use of the finite element method which permits the study of drawbead effects on sheet metal flow in three dimensions. Finally, the potential of active drawbeads is described based upon ongoing research which is directed toward closed-loop computer control of the stamping process through adjustment of the drawbead penetration.
Technical Paper

Critical Engine Geometry Generation for Rapid Powertrain Concept Design Assessment

1998-02-23
981090
This paper presents some of the design rules used to calculate critical geometry of engine components, and the object-oriented component hierarchy system in PET. This paper also presents parametric solid model assembling schemes used to dynamically construct an assembly of whole powertrain systems. Some examples of powertrain concept design, such as the estimation of friction, packaging, and moving component clearances, will be presented. The computational efficiency of this concept design method will be compared to traditional methods also.
Technical Paper

Matching Ignition System Multi-Spark Calibration to the Burn-Rate of an Engine to Extend Ignitability Limits

1998-02-23
981046
“Multi-Spark” refers to the charging and discharging of an ignition coil multiple times during a single combustion event. This paper attempts to use multi-sparking to achieve an effect similar to a long duration spark to enhance combustion during slow burn conditions. Although multi-sparking is more typical of capacitive discharge (CDI) ignition systems, this paper discusses the multi-sparking of Kettering ignition systems to achieve the benefits of multi-sparking without CDIs' cost, packaging, complexity and reliability issues. The goal of the multi-spark calibration is to successfully initiate flame kernal development with the first spark discharge and add supplemental energy fast enough through restriking to prevent the flame kernal from quenching.
Technical Paper

Current and Past Technologies for Headliners Including Acoustics, Recycling and Safety

1998-02-23
980951
Headliner technology will be presented in this paper. Older established technologies such as cut & score, fiberglass, hardboard and resinated cotton are still used because of their proven reliability and low cost. But newer processes including polyester, natural fiber, Tramivex™ and urethane offer reliability, structure, acoustic performance and some recyclability. Fiberglass has always been a leader in acoustical performance but has breakage and handability issues in the assembly plants. This paper will be divided in four sections. The first section discusses manufacturing processes for headliners covering current and past. It also covers the materials used and types of facing. This section will state why headliner technology used in the USA is different than Europe or emerging markets. Second section describes acoustics. It will explain performance as related to material types. Porosity, cell type, fiber length and diameter is explained as it relates to the absorption of sound.
Technical Paper

Design and Development of 25% Post-Industrial Recycled SMC Hood Assembly for the 1998 Lincoln Continental Program

1998-02-23
981019
This paper describes the process of incorporation of 25% post-industrial recycled sheet molded composite (SMC) material in the 1998 Continental Hood inner. 1998 Continental Hood assembly consists of traditional SMC outer and this recycled hood inner along with three small steel reinforcements. BUDD Plastics collects SMC scraps from their manufacturing plants. The scrap is then processed and made into fillers for production of SMC. Strength of SMC comes from glass fibers and fillers are added to produce the final mix of raw materials. This recycled material is approximately 10% lighter and less stiff than the conventional virgin SMC. This presented unique challenges to the product development team to incorporate this material into a production vehicle in order to obtain the desired goal of reducing land fill and improving the environment.
Technical Paper

A Protocol for Testing and Evaluation of Paint Spray Applicators for the Automotive Industry

1998-09-29
982289
In this paper we discuss the development of a paint applicator system test protocol developed by Ford Motor Company. The test protocol involves spraying commercially available automotive primers, basecoats and clearcoats with known characteristics onto 90 cm long by 30 cm wide phosphated panels (36 in by 12 in) at application conditions necessary to obtain a typical range of film builds. The film builds are then measured at frequent intervals to obtain build averages, standard deviations, and spray pattern sizes. From these, transfer efficiency and pattern uniformity are obtained. In addition, the quality of the applied paint is measured at well defined film builds using several instruments to determine whether the application system being tested is capable of achieving the superb appearance demanded by our customers. Details of the required test matrix, the measurement templates and some comparative results obtained using the Ford protocol will be presented.
Technical Paper

An Experimental Investigation of Spray Transfer Processes in an Electrostatic Rotating Bell Applicator

1998-09-29
982290
A better understanding is needed of the electrostatic rotating bell (ESRB) application of metallic basecoat paint to automobile exteriors in order to exploit their high transfer efficiency without compromising the coating quality. This paper presents the initial results from experimental investigation of sprays from an ESRB which is designed to apply water-borne paint. Water was used as paint surrogate for simplicity. The atomization and transport regions of the spray were investigated using laser light sheet visualizations and phase Doppler particle analyzer (PDPA). The experiments were conducted at varying levels of the three important operating parameters: liquid flow rate, shaping-air flow rate, and bellcup rotational speed. The results show that bellcup speed dominates atomization, but liquid and shaping-air flow rate settings significantly influence the spray structure. The visualization images showed that the atomization occurs in ligament breakup regime.
Technical Paper

Engineering Moveable Glass Window Seals of Automotive Door Using Upfront CAE

1998-09-29
982383
The traditional moveable glass window seal development process has relied heavily on physical prototypes for design verification. Due to frequent styling changes and an overall reduction in design time, physical prototypes for the glass window seals have proven to be inadequate. Utilization of computer aided engineering (CAE) tools is necessary in order to shorten lead time. CAE tools will help to decrease expensive prototyping, free up valuable manufacturing line time, and improve overall quality. A cross functional approach has been applied to expand the scope beyond traditional methods of moveable glass window seal design, such as wedged boarding, into new computerized modeling methods. The CAE was used to address major requirements of the glass window seals including glass velocity, glass stall force, sealing-ability, seal durability, seal assembly, seal appearance, and regulator motor current.
Technical Paper

Paint Inspection Lighting

1998-09-29
982315
An improved defect detection system for painted surfaces has been developed which significantly increases topographic defect visibility (dirt-in-paint, sags/runs/drips, sealer-under-paint, spits, craters, etc.) for the final inspector / polisher. These minor defects can then be repaired before leaving the “spillout” deck. A new luminaire was designed to maximize the contribution of several applicable principles. The new process has significantly reduced the number of defects leaving the spillout area, doubled the number of “zero defect” vehicles, and increased energy savings from 25-40%. The improved Paint Inspection Lighting process was issued as a Uniform Process specification by the Ford Motor Company Vehicle Operations and was implemented in all of the Ford North American assembly plants.
Technical Paper

Laser & Fine Plasma Trimming of Sheet Metal Parts for Low Volume Production

1998-09-29
982333
This study compared laser and fine plasma technology for cutting typical electro-galvanized steel and aluminum automotive stampings. Comparisons were made of various aspects of cut quality, accuracy, disturbance of parent material, cycle time, and capital and operating costs. A sensitivity analysis was included to determine how different scenarios would impact the operating costs. It was found that both processes were capable of high quality cuts at 3800mm/min. Capital savings were achievable through the fine plasma system, but careful consideration of the specific application was essential. This work will allow for an advised comparison of options for sheet metal flexible cutting.
Technical Paper

Comparison of Analytically and Experimentally Obtained Residual Fractions and NOX Emissions in Spark-Ignited Engines

1998-10-19
982562
Using a fast-sampling valve, residual-fraction levels were determined in a 2.0L spark-ignited production engine, over varying engine operating conditions. Individual samples for each operating condition were analyzed by gas-chromatography which allowed for the determination of in-cylinder CO and CO2 levels. Through a comparison of in-cylinder measurement and exhaust data measurements, residual molar fraction (RMF) levels were determined and compared to analytical results. Analytical calculations were performed using the General Engine SIMulation (GESIM) which is a steady state quasi-dimensional engine combustion cycle simulation. Analytical RMF levels, for identical engine operating conditions, were compared to the experimental results as well as a sensitivity study on wave-dynamics and heat transfer on the analytically predicted RMF. Similarly, theoretical and experimental NOx emissions were compared and production sensitivity on RMF levels explored.
Technical Paper

A New Multi-point Active Drawbead Forming Die: Model Development for Process Optimization

1998-02-01
980076
A new press/die system for restraining force control has been developed in order to facilitate an increased level of process control in sheet metal forming. The press features a built-in system for controlling drawbead penetration in real time. The die has local force transducers built into the draw radius of the lower tooling. These sensors are designed to give process information useful for the drawbead control. This paper focuses on developing models of the drawbead actuators and the die shoulder sensors. The actuator model is useful for developing optimal control methods. The sensor characterization is necessary in order to develop a relationship between the raw sensor outputs and a definitive process characteristic such as drawbead restraining force (DBRF). Closed loop control of local specific punch force is demonstrated using the die shoulder sensor and a PID controller developed off-line with the actuator model.
Technical Paper

High Temperature Stability of Ceria-Zirconia Supported Pd Model Catalysts

1998-02-23
980668
A series of ceria and ceria-zirconia supported Pd model automotive catalysts were prepared and aged under air or redox conditions at 1050°C for 12 h. The supports were manufactured by different methods and represent a range of compositions. The samples were characterized before and after aging by BET, X-ray diffraction, mercury porosimetry, XPS, H2 temperature-programmed reduction, and oxygen storage capacity measurements. Oxygen storage measurements revealed that the behavior of the catalysts varied according to aging conditions and temperature of measurement. Pd/ceria-zirconia catalysts showed higher oxygen storage characteristics after 1050°C aging than Pd/ceria catalysts, and the phase purity of the ceria-zirconia was shown to positively affect the amount of oxygen storage. The initial rates of oxygen release from the model catalysts at 350°C were shown to depend on the preparation conditions of the supports.
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