Refine Your Search

Topic

Author

Search Results

Technical Paper

Aluminum Rail Rivet and Steel Rail Weld DOE and CAE Studies for NVH

2001-04-30
2001-01-1608
Vehicle body with aluminum riveted construction instead of steel welded one will be a big challenge to NVH. In this paper, aluminum and steel rails with the dimensions similar to the rear rail portion of a typical mid-size sedan were fabricated. Rivets were used to assemble the aluminum rails while welds were used to assemble the steel rails. Adhesive, rivet/weld spacing, and rivet/weld location were the three major factors to be studied and their impact on NVH were investigated. The DOE matrix was developed using these three major factors. Modal tests were performed on those rails according to the DOE matrix. The FEA models corresponding to the hardware were built. CAE modal analysis were performed and compared with test data. The current in-house CAE modeling techniques for spot weld and adhesive were evaluated and validated with test data.
Technical Paper

Analysis of Instabilities and Power Flow in Brake Systems with Coupled Rotor Modes

2001-04-30
2001-01-1602
Recent investigations by others have indicated that the dynamic response of automotive brake rotors in the squeal frequency range involves the classic flexural modes as well as in-plane motion. While the latter set creates primarily in-plane displacements, there is coupling to transverse displacements that might produce vibrational instabilities. This question is investigated here by analyzing a modal model that includes two modes of the rotor and two modes of the pad and caliper assembly. Coupling between in-plane and transverse displacements is explicitly controlled. Results from this model indicate that the coupling does create vibrational instabilities. The instabilities, whose frequencies are in the squeal range, are characterized by power flow through the transverse motion of the rotor.
Technical Paper

Gear Whine Improvements for an Automatic Transmission through Design Retargeting and Manufacturing Variability Reduction

2001-04-30
2001-01-1505
Gear whine in 1st gear for an automatic transmission that has been in production for nearly thirty years was identified as an NVH issue. Due to advances in vehicle level refinement, and reduction of other masking noises, the automatic transmission gear whine became an issue with the customer. Since the transmission was already in production, the improvements had to be within the boundaries of manufacturing feasibility with existing equipment to avoid costly and time consuming investment in new machines. The approach used was one of identifying optimum values of existing gear parameters to provide a reduction in passenger compartment noise. The problem was in a light truck application. Objective noise measurements were recorded for 10 transmissions from more than 50 driven in vehicles. The transmissions were disassembled and the gears inspected.
Technical Paper

Eliminating Piston Slap through a Design for Robustness CAE Approach

2003-05-05
2003-01-1728
Piston slap is a problem that plagues many engines. One of the most difficult aspects of designing to eliminate piston slap is that slight differences in operating conditions and in part geometries from build to build can create large differences in the magnitude of piston slap. In this paper we will describe a design for robustness CAE approach to eliminating piston slap. This approach considers the variations of the significant control factors in the design, e.g. piston pin offset, piston skirt design, etc. as well as the variation in the noise factors the system is subjected to, e.g. assembly clearance, skirt collapse, peak cylinder pressure, cylinder pressure rise rate, and location of peak cylinder pressure. Using analytical knowledge about how these various factors impact the generation of piston slap, a piston design for low levels of piston slap can be determined that is robust to the various noise factors.
Technical Paper

Finite Element Prediction of Backlite Molding Squeak Noise

1997-02-24
970584
The backlite molding squeak noise is caused by the stick-slip type of friction between the window molding and the body panel. To predict if the molding would squeak a finite element analysis technique which uses the nonlinear explicit code LS-DYNA3D has been developed. The three dimensional finite element simulation technique is based on the threshold displacement velocity spectrum and the relative movement of the window glass with respect to the body panel. Comparisons between FEA analysis and tests are also presented in this paper.
Technical Paper

“Next Generation” Means for Detecting Squeaks and Rattles in Instrument Panels

1997-05-20
972061
Engineers doing squeak and rattle testing of instrument panels (IP's) have successfully used large electrodynamic vibration systems to identify sources of squeaks and rattles (S&R's). Their successes led to demands to test more IP's, i.e., to increase throughput of IP's to reflect the many design, material, and/or manufacturing process changes that occur, and to do so at any stage of the development, production, or QA process. What is needed is a radically different and portable way to find S&R's in a fraction of the time and at lower capital cost without compromising S&R detection results.
Technical Paper

Statistical Energy Analysis for Road Noise Simulation

1997-05-20
971972
Statistical Energy Analysis (SEA) is being actively pursued in the automotive industry as a tool for vehicle high frequency noise and vibration analysis. A D-class passenger car SEA model has been developed for this purpose. This paper describes the development of load cases for the SEA model to simulate road noise on rumble road. Chassis roll test with rough shells was performed to simulate rumble road noise. Sound radiation from tire patch and vibration transmission through spindles were measured to construct the SEA load cases. Correlation between SEA model predictions and measured data was examined. Test and SEA result comparisons have shown that simulation of airborne road noise requires only a trimmed body SEA model, while simulation of structure-borne road noise may require SEA modeling of chassis components.
Technical Paper

Powertrain Applications for Rapid Prototyping, Fabrication and Tooling in Motorsports

1998-11-16
983091
Rapid Prototyping, Fabrication and Tooling is a process that blends a series of technologies (machines, tools, and methods) capable of generating physical objects directly from a CAD database. The process dramatically reduces the time spent during product development by allowing for fast visualization, verification, iteration, optimization, and fabrication of parts and tools. Many new techniques of tooling have been and are being developed by using rapid fabricated parts. These are having a dramatic impact on both timing and costs throughout the automotive industry. One area that these methods can be utilized to their full potential is motorsports. Of particular interest is the growing use of bridge tooling to provide first article through production intent parts that promote cost effective changes.
Technical Paper

A Comparative Study of the Fatigue Behavior of Spot Welded and Mechanically Fastened Aluminum Joints

1995-02-01
950710
The cyclic behavior of single overlap aluminum joints joined through a number of different methods has been investigated using Alcan 5754-O, an alloy that potentially could be used in structural applications. Overlap shear tests of spot welded, clinched and riveted joints are compared on the basis of their fatigue performance. The fatigue response of the spot welded joint was the baseline to which the other fasteners were compared. Test results showed an improvement of approximately 25% for both the mechanical clinch joints and aluminum rivets in fatigue strength at 106 cycles. The most significant improvement in fatigue strength of 100% was found for the self piercing rivets at 106 cycles. The failure behavior of the various joining methods is discussed as well as the surface appearance.
Technical Paper

Effect Pre-Consumer Reclaim on S/MA-GR Property Retention

1996-02-01
960699
A process was developed and commercialized by Ford Motor Company, ACD for the recovery of S/MA-GR (glass fiber reinforced styrene maleic anhydride copolymer) resin from trim offal and rejected composite foam instrument panels, SAE# 93005. This high quality, low contaminate level “Reclaim”, S/MA-GR resin, has very good physical property retention through the manufacturing cycle. It compares favorably to post consumer “recycle” S/MA-GR resin recovered from Arizona. Acrylic (PMMA) resin recovered from manufacturing tail lamp lenses, etc. and post consumer applications was compounded with S/MA and fiberglass. This S/MA-GR compound has improved acrylic dispersion, uniform fiberglass content and improved mechanical properties: Dylark ® 378 P20A. The adverse effects of acrylic regrind on S/MA Boss/Joint Performance as described in SAE# 95810 should be minimized by reducing the variability incurred by blending regrind acrylic at the molding machine.
Technical Paper

Effect of Post Consumer Recyclate on SMA Copolymer Boss/Joint Performance

1996-02-01
960698
The use of Post Consumer Recyclate (PCR) or Post Industrial Regrind (PIR) to manufacture thermoplastic (or thermoset) automotive parts and components has significantly increased over the last 10 years. Due to this increase in use, automotive designers are continuously challenged with the question of how PCR or PIR material differ in performance from the virgin material? To compound the dilemma, automotive OEMs are requiring increased durability of thermoplastic attachments (joints), so that warranty costs associated with interior squeak and rattle (from ill-fitting joints) are minimized. To answer this question, there exist several techniques for finding thermoplastic joint durability performance. Some of them are: strip-to-drive torque ratios, screw pull-off force and clamp load fall-off. A thermoplastic attachment (i.e. boss) which experiences clamp load fall-off will lead to a loose fitting joint and subsequently result in squeaks and rattles.
Technical Paper

Geometric and Thermal Characterization of a Machining Center Under Dry and Wet Conditions

1996-05-01
961640
Quantification of geometric and thermal characteristics of machinery is critical to the improvements in part dimensional accuracy and reduction of part to part dimensional variations in a high volume manufacturing operations. Assembly and alignment of different components in a machine result in geometric error over the machining volume of a machine. These errors, once quantified, can be corrected through offsets in positioning controls. The objectives of a good machine design should be to minimize the geometric errors during fabrication and assembly of the components, and replacement of the wear prone components during maintenance of the machine in operations. Thermal errors in machines are even more critical and have not been addressed sufficiently in improving part to part dimensional variations.
Technical Paper

Enhanced Machining Center Accuracy Through Real Time Error Compensation

1996-05-01
961641
There is an ever increasing demand on part quality and tighter tolerances for machining of components in high volume manufacturing. A major source of problem in the machine tools is the thermally induced error due to thermal gradients and uneven heating and expansion of various machine components. Current practice of manufacturing precision parts involves periodic gaging of parts, whereby, production is interrupted and manual compensating offsets are input to the controller. Also, additional production costs are introduced due to requirement of initial warm up cycles without cutting parts and utilization of chillers for temperature controlled coolants. In this paper, a methodology is described for automatic compensation for thermal error by means of components/locations temperature profile and calculated error between the tool tip and the workpiece.
Technical Paper

Drilling Burr Characterization Using Semantic Differential Method

1996-05-01
961643
The semantic differential (SD) method was used to characterize the size and shape of burrs created under various cutting conditions, drill size, tool geometry and coatings. Human subjects visually rated the burr using a SD evaluation form. Significant differences were found in tool type and feed rate. A high performance drill with titanium-nitride coating and a high depth/diameter ratio, yielded minimum burr. A lower feed rate resulted in less burr formation in the majority of the cases. Three primary factors emerged, and accounted for 83% of the variances. Factor scores were mapped into the SD space to show the effect of treatments.
Technical Paper

Understanding the Mechanical Behavior of Threaded Fasteners in Thermoplastic Bosses Under Load

1996-02-01
960293
Because it is common to attach plastic parts to other plastic, metal, or ceramic assemblies with mechanical fasteners that are often stronger and stiffer than the plastic with which they are mated, it is important to be able to predict the retention of the fastener in the polymeric component. The ability to predict this information allows engineers to more accurately estimate length of part service life. A study was initiated to understand the behavior of threaded fasteners in bosses molded from engineering thermoplastic resins. The study examined fastening dynamics during and after insertion of the fastener and the effects of friction on the subsequent performance of the resin. Tests were conducted at ambient temperatures over a range of torques and loads using several fixtures that were specially designed for the study. Materials evaluated include modified-polyphenylene ether (M-PPE), polyetherimide (PEI), polybutylene terephthalate (PBT), and polycarbonate (PC).
Technical Paper

Bolt-Load Retention and Creep of Die-Cast Magnesium Alloys

1997-02-24
970325
New high-temperature Mg alloys are being considered to replace 380 Al in transmission cases, wherein bolt-load retention, and creep, is of prime concern. One of these alloys is die cast AE42, which has much better creep properties than does AZ91D but is still not as creep resistant as 380 Al. It is thus important to investigate bolt-load retention and creep of AE42 as an initial step in assessing its suitability as a material for transmission housings. To that end, the bolt-load retention behavior of die-cast AE42, AZ91D and 380 Al have been examined using standard M10 bolts specially instrumented with stable high-temperature strain gages. The bolt-load retention test pieces were die cast in geometries approximating the flange and boss regions in typical bolted joints. Bolt-load retention properties were examined as a function of time (at least 100 hours), temperature (150 and 175 °C) and initial bolt preload (14 to 34 kN).
Technical Paper

Joint Alternatives for Dual Inlet Mufflers

1996-10-01
962167
A joint system for a dual inlet muffler has been designed which allows the muffler system to be better aligned during assembly. The system uses a slip-fit joint coupled with a ball-and-flair joint. This combination decreases variations in manufacturing and assembly thus, improving tailpipe variability in the vehicle build. The slip-fit/ball-flair joint was compared to conventional inlet systems of flat flanges and flex-couplings. A Variable Simulation Analysis (VSA) audit, finite element analysis of the joint strengths, and variable cost study all showed advantages for the slip-fit/ball-flair system.
Technical Paper

A Novel Approach to Statistical Energy Analysis Model Validation

1995-05-01
951328
Statistical Energy Analysis (SEA) is a tool for estimating the response of complex dynamic systems at high modal density. This tool is seeing ever wider application in a range of industries, including aerospace industry, marine industry, and building trades. The automotive industry is beginning to explore the application of SEA to high frequency vehicle acoustic design. The SEA model of vibrational power transmission has a direct analogy to thermal power transmission (diffusion). As thermal power flow is proportional to temperature difference, vibrational power flow is proportional to modal energy difference. In this paper the thermal analogy is exploited to visualize the SEA results. This is accomplished by color coding a finite element representation of the structure. In this paper, the thermal analogy is used to correlate test data with SEA model results. This is accomplished by constructing a test based modal power thermogram.
Technical Paper

The Effect of Chemicals and Solvents on Plastics -An Engineering Practice Guide

1995-02-01
950634
The presence of a foreign substance on or within a polymer often affects the mechanical, chemical and thermal properties of the material. The change in strength and rigidity of a polymer resulting from the plasticizing action of a sorbed chemical or due to the withdrawal of an added plasticizer by the leaching operation can seriously affect the useful life of the material. In the real engineering world, incompatible chemicals and lubricants get onto various plastic components unexpectedly through design, manufacturing processes, customers services and repairs. This paper presents a number of case-studies which illustrate how undesirable chemicals found on plastic parts can affect product performance and cause damage to the parts.
Technical Paper

A New Method Development to Predict Brake Squeal Occurrence

1994-11-01
942258
A new method to predict brake squeal occurrence was developed by MSC under contract to Ford Motor Company. The results indicate that the stability characteristics of this disc brake assembly are governed mainly by the frictional properties between the pads and rotor. The stability is achieved when the friction coefficient of the pads is decreasing as the contact force increases. Based on the results, a stable brake system can be obtained without changing the brake structure by incorporating the appropriate frictional coefficient in the brake system. The method developed here can be also used as a tool to test the quality of any brake design in the early design stage.
X