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Technical Paper

Material Damping Properties: A Comparison of Laboratory Test Methods and the Relationship to In-Vehicle Performance

2001-04-30
2001-01-1466
This paper presents the damping effectiveness of free-layer damping materials through standard Oberst bar testing, solid plate excitation (RTC3) testing, and prediction through numerical schemes. The main objective is to compare damping results from various industry test methods to performance in an automotive body structure. Existing literature on laboratory and vehicle testing of free-layer viscoelastic damping materials has received significant attention in recent history. This has created considerable confusion regarding the appropriateness of different test methods to measure material properties for damping materials/treatments used in vehicles. The ability to use the material properties calculated in these tests in vehicle CAE models has not been extensively examined. Existing literature regarding theory and testing for different industry standard damping measurement techniques is discussed.
Technical Paper

Methodology On The Testing Of The Automobile Mount Dynamic Response

2001-03-05
2001-01-0474
This paper reports the latest development of methodologies for testing and CAE modeling of the automobile mounts. The objective of this study is to provide dynamic mount properties for product evaluation and CAE modeling guideline for crashworthiness simulations. The methodology is divided into component, subsystem and full system levels. The study at the component level is to extract the dynamic parameters of mounts, such as stiffness and damping coefficient, based on the component tests. Furthermore, such parameters are employed to investigate the interaction between mount and connecting structures at the subsystem level. A robust connection mechanism from mount to surrounding structures is also developed during this process. Finally, the results from full vehicle system tests are compared with the CAE simulations to verify the methodology at the component and subsystem levels. A robust component test methodology is the first key element of this study.
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

An Assessment of a FEA NVH CAE Body Model for Design Capability

2001-04-30
2001-01-1401
Finite Element Analysis (FEA) models are routinely being adopted as a means of up-front design for automotive body structure design. FEA models play two important functions: first as a means of assessing design versus an absolute target; secondly they are used to assess the performance of design alternatives required to meet targets. Means of assessing model capability versus task is required to feed appropriate information into the design process. Being able to document model capability improves the credibility of the FEA model information. A prior paper addressed assessing the absolute performance of model technology using a metric based on a statistical hypotheses test that determines membership in a reference set. This paper extends the use of quality technology to determining the capability of the FEA model to span the design space using Designed Experiments.
Technical Paper

Influence of Mount Stiffness on Body/Subframe Acoustic Sensitivities

2003-05-05
2003-01-1714
A comparison of acoustic sensitivities of the 2000 Ford Taurus and 1999 Toyota Camry identifies an interesting paradox: the Taurus has a competitive advantage over the Camry when comparing body-only transfer functions, but a handicap to the Camry when the subframe is included in the measurements. Further, the Taurus subframe/mount subsystem actually behaves as an amplifier rather than an isolator over most of the powertrain excited frequency range. This report attempts to explain the cause of these behaviors through a hybrid CAE/test method and recommends a design strategy to lower the Subframe to Driver's Right Ear sensitivities of the Taurus.
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

Chassis System Integration Approach for Vehicle High Mileage NVH Robustness

1998-02-23
980903
High mileage NVH performance is one of the major concerns in vehicle design for long term customer satisfaction. Elastomeric bushings and brake rotors are key chassis components which tend to degrade as vehicle mileage accumulates with time. The degradation of these components normally causes the overall degradation of vehicle NVH performance. In the current paper two categories of problems are addressed respectively: road-induced vibration due to bushing degradation, and brake roughness due to rotor wear. A system integration approach is used to derive the design strategies that can potentially make the vehicle more robust in these two NVH attributes. The approach links together bushing degradation characteristics, brake rotor wear characteristics, the design of experiment (DOE) method, and CAE modeling in a systematic fashion. The concept and method are demonstrated using a production vehicle.
Technical Paper

Design and Development of Method of Valve-Train Friction Measurement

1998-02-23
980572
The general trend in the IC engine design has been towards reduction in fuel consumption since the 1973 oil embargo. The improvement in combustion process has contributed greatly to a better fuel economy of today's engine and there are many challenges ahead on the GDI front towards the 3L/100km engine [1]. One of the biggest windows of opportunity in achieving higher engine fuel efficiency together with an acceptable emissions level is to reduce its friction. To achieve these an accurate method of assessing friction levels through the concept, design and development is paramount. Translation of friction torque to the total drive cycle's fuel consumption is carried out using Ford's in-house CAE analytical packages. A new method of directly measuring camshaft friction has been developed, which offers both exceptional accuracy and unprecedented convenience.
Technical Paper

Light Truck Stabilizer Bar Attachment Non-linear Fatigue Analysis

1998-11-16
982833
The stabilizer bar attachments problem can not be simply analyzed by using linear FEA methodology. The large deformation in the bushing, the elastic-plastic material property in the bushing retainer bracket, and the contact between different parts all add complexity to the problem and result in the need for an analysis method using a non-linear code, such as ABAQUS. The material properties of the bushing were experimentally determined and applied to the CAE model. It was found that using strains to estimate the fatigue life was more accurate and reliable than using stress. Many modeling techniques used in this analysis were able to improve analysis efficiency.
Technical Paper

1983 Ranger Pickup

1981-11-01
811270
The Ford Ranger will be a domestically built, small pickup truck engineered to many design objectives typical of a fullsize pickup, yet with four cylinder engine fuel efficiency. Ranger is a full-function on-and-off road pickup truck with a uniquely smooth ride and a capacity to carry up to a 725.7 kg. (1600 lb.) payload. The truck features a three passenger body-on-frame cab and a double wall pickup box with provision for 1.2m × 2.4m (4 ft. × 8 ft.) sheets of construction material. Featured in this comprehensive paper are the engineering highlights and innovations contributing to the accomplishment of these Small Truck objectives.
Technical Paper

CAE Simulation of Engine Oil Pump Tonal Noise: Design Modifications and Countermeasures

2017-03-28
2017-01-1076
In this presentation, two cases of CAE simulations of oil pump-induced tonal noises are presented. The first case involves oil pump-induced whine in an I4engine during coast down. The second case addresses oil pan moan during hot idle and the effect of oil pump pick-up tube positioning inside the oil pan of an I5 engine. The investigations include several design modifications to the pump and the pick-up tube to prevent the tonal noise. Test data are also included to demonstrate the accuracy of the CAE simulation.
Technical Paper

Geometrical Optimization of an Automotive Halfshaft

2017-03-28
2017-01-1125
Halfshafts are very important components from vehicle powertrain. They are the element responsible to transmit torque and rotation from transmission to wheels. Its most basic design consists of a solid bar with joints at each extreme. Depending of bar length, the natural frequency of first bending mode might have a modal alignment with engine second order, resulting in undesired noise on vehicle interior. Many design alternatives are available to overpass this particular situation, like adding dampers, use tube shafts or use link-shafts, however, all of them are cost affected. This study proposes an investigation to obtain an optimal profile for a solid shaft, pursuing the lowest possible frequency for the first bending mode by changing its diameter at specific regions. The study is divided in four main stages: initially, a modal analysis of a halfshaft is done at vehicle to determinate its natural frequency when assembled on vehicle.
Technical Paper

Folded Pelvis-Thorax Side Airbag Modeling with CFD Approach and Implementation in Full Vehicle Crash Analysis

2017-03-28
2017-01-1460
The Pelvis-Thorax Side Air Bag (PTSAB) is a typical restraint countermeasure offered for protection of occupants in the vehicle during side impact tests. Currently, the dynamic performance of PTSAB for occupant injury assessment in side impact is limited to full-vehicle evaluation and sled testing, with limited capability in computer aided engineering (CAE). The widely used CAE method for PTSAB is a flat bag with uniform pressure. The flat PTSAB model with uniform pressure has limitations because of its inability to capture airbag deployment during gap closure which results in reduced accuracy while predicting occupant responses. Hence there is a need to develop CAE capability to enhance the accuracy of prediction of occupant responses to meet performance targets in regulatory and public domain side impact tests. This paper describes a new CAE methodology for assessment of PTSAB in side impact.
Technical Paper

Engine Flywheel Failure Avoidance through CAE Optimization

2017-03-28
2017-01-1024
A Flywheel is a rotating mechanical device that evens out the energy fluctuations of an engine and establishes an even crank rotational speed by storing kinetic energy. This paper aims to study the effect of the potential failures on flywheel due to balancing hole position for a proposed grey cast iron material. Any change in its design requires a thorough comprehension of the expected failure modes during operation. For a flywheel, typical failure like crack is very critical for vehicle and occupant safety. Here, CAE test method is adopted for simulating the actual bench tests for design validation of the flywheel. This simulation helps to understand the stresses caused by the structural and thermal loads and recommend design solution which can be readily adopted. The simulation is followed by a rig test where the validation tests are performed for different balancing hole depths. The study revealed that 1. Balancing hole have immense role in crack initiation 2.
Technical Paper

Time to Torque Optimization by Evolutionary Computation Methods

2017-03-28
2017-01-1629
Time to torque (TTT) is a quantity used to measure the transient torque response of turbocharged engines. It is referred as the time duration from an idle-to-full step torque command to the time when 95% of maximum torque is achieved. In this work, we seek to control multiple engine actuators in a collaborative way such that the TTT is minimized. We pose the TTT minimization problem as an optimization problem by parameterizing each engine actuator’s transient trajectory as Fourier series, followed by minimizing proper cost function with the optimization of those Fourier coefficients. We first investigate the problem in CAE environment by constructing an optimization framework that integrates high-fidelity GT (Gamma Technology) POWER engine model and engine actuators’ Simulink model into ModeFrontier computation platform. We conduct simulation optimization study on two different turbocharged engines under this framework with evolutionary computation algorithms.
Technical Paper

Safe Handling of Floating Point Math in C Code Embedded Applications

2017-03-28
2017-01-1619
The introduction of floating point math in Embedded Application ECU’s has made the implementation of complex math functions less error prone but not error proof. This paper shall focus on raising awareness of the pitfalls that come from the use of the basic floating point arithmetic operations, that is, Divide, Multiply, Add and Subtract. Due to the known pitfalls inherent in these basic math operations, it is proposed that a standard library with common functions appropriate for Powertrain Embedded applications (but not limited to Powertrain) be identified. This paper shall explore what these common functions will look like for both standard C code as well as the equivalent versions in Matlab™ Simulink™. The particular pitfalls this paper shall discuss are Divide-By-Zero, Overflow, Underflow and Loss-Of-Precision for both single and double precision floating point variables. This paper shall reference the IEEE-754 Floating Point standard used by most Embedded C applications.
Technical Paper

Use of Plastic Trim Fasteners for Automotive Trimming Applications

2017-03-28
2017-01-1304
For many years, the use of in-mold fasteners has been avoided for various reasons including: not fully understanding the load cases in the part, the fear of quality issues occurring, the need for servicing, or the lack of understanding the complexity of all failure modes. The most common solution has been the use of secondary operations to provide attachments, such as, screws, metal clips, heat staking, sonic welding or other methods which are ultimately a waste in the process and an increase in manufacturing costs. The purpose of this paper is to take the reader through the design process followed to design an in-molded attachment clip on plastic parts. The paper explores the design process for in-molded attachment clips beginning with a design concept idea, followed by basic concept testing using a desktop 3D printer, optimizing the design with physical tests and CAE analysis, and finally producing high resolution 3D prototypes for validation and tuning.
Technical Paper

Towards a One Day Frame Model Build

2017-03-28
2017-01-1314
Virtual Verification (VV) of engineering designs is a critical enabler in the Product Development (PD) process to reduce the time-to-market in a cost efficient manner. Reliance on cost effective VV methods have significantly increased with increased pressure to meet customer expectations for new products at reduced PD budgets. Computer Aided Engineering (CAE) is one such VV method that affords an engineer to make decisions about the ability of the designs to meet the design criteria even before a prototype is built. The first step of the CAE process is meshing which is a time consuming, manual and laborious process. Also mesh development time and accuracy significantly varies with the (1) component (trim body, engine, suspension, brakes, etc.), (2) features predominantly occurring in the component (welds, ribs, fillets, etc.), meshing guidelines based on which the model needs to be developed (durability, safety, NVH, etc.), and the expertise of the meshing engineer involved.
Technical Paper

Analytical Prototype Model Development - Continuous Model Build Approach

2017-03-28
2017-01-1312
Computer Aided Engineering (CAE) has been widely utilized as an essential component of the product development phase in the automotive industry. Every successful automotive company has established its own design and development approach in order to build competitive, better and safer cars, in a more cost-effective manner. In an ever demanding automotive sector, every key player wants its products to be hitting the roads at shorter intervals but also develop them to be highly competitive. Ford product development processes define the multiple phases of the product development progression and timeline. For each of the phases, Vehicle CAE models are built to assess Vehicle NVH / Durability/ Safety/ Thermal & Aero and other performances. The design level of the input data and the data availability timings, to build the Vehicle CAE models, play a significant role in determining the quality and timing of the product development progression.
Technical Paper

Effective Application of CAE Guidance for Hemmed Closures Throughout the Vehicle Development Process

2017-03-28
2017-01-1310
The perceived quality of automotive closures (flushness and margin) is strongly affected by flanging and hemming of the outer panels and assembly respectively. To improve the quality of closures, the traditional hardware approach needs significant amount of time and costly die re-cuts and trials with prototype panels. Thus, such approach may delay the vehicle program and increase the overall investment cost. The proposed CAE methodology provides upfront design guidance to dies and panels, reduces time and increases cost savings associated with flanging and hemming while improving overall quality of the closures. In this proposed approach, as a first step, analytical formulae and design of experiments (DOE) are followed to estimate magnitude of design parameters of panels and dies as the upfront design guidance.
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