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Technical Paper

Flow Noises Associated with Integrated Compressor Anti-Surge Valve

2011-05-17
2011-01-1532
Turbocharged gasoline engines are typically equipped with a compressor anti-surge valve or CBV (compressor by-pass valve). The purpose of this valve is to release pressurized air between the throttle and the compressor outlet during tip-out maneuvers. At normal operating conditions, the CBV is closed. There are two major CBV mounting configurations. One is to mount the CBV on the AIS system. The other is to mount the CBV directly on the compressor housing, which is called an integrated CBV. For an integrated CBV, at normal operating conditions, it is closed and the enclosed passageway between high pressure side and low pressure side forms a “side-branch” in the compressor inlet side (Figure 12). The cavity modes associated with this “side-branch” could be excited by shear layer flow and result in narrow band flow noises.
Journal Article

An Advanced and Comprehensive CAE Approach of Piston Dynamics Studies for Piston Optimal and Robust Design

2011-04-12
2011-01-1404
A successful piston design requires eliminate the following failure modes: structure failure, skirt scuffing and piston unusual noise. It also needs to deliver least friction to improve engine fuel economy and performance. Traditional approach of using hardware tests to validate piston design is technically difficult, costly and time consuming. This paper presents an up-front CAE tool and an analytical process that can systematically address these issues in a timely and cost-effectively way. This paper first describes this newly developed CAE process, the 3D virtual modeling and simulation tools used in Ford Motor Company, as well as the piston design factors and boundary conditions. Furthermore, following the definition of the piston design assessment criteria, several piston design studies and applications are discussed, which were used to eliminate skirt scuffing, reduce piston structure dynamic stresses, minimize skirt friction and piston slapping noise.
Technical Paper

CAE Methodology for Optimizing NVH, Functional Reliability, and Mass Reduction at Engine Concept Design Phase

2011-05-17
2011-01-1511
Due to the global economic downturn and higher environmental awareness, the social demands for low cost and fuel efficient vehicles are increasing. At the same time the engine power is increasing and customer expectations of reliability and NVH levels are increasing. To meet all the requirements, engineers are challenged to design light weight parts with higher performance. However, unconsidered mass reduction carries a risk of compromised NVH, Functional Reliability, and other functional demands. In order to resolve this contradiction, it is important to establish a basic structure with minimum necessary mass at the concept design phase, when there are still many degrees of freedom in the design space. Hence, a multi-objective optimization CAE methodology applicable for designing the basic structure of the Engine system was developed and is detailed below.
Technical Paper

Optimization of Gear Whine, Efficiency, and Durability of a Manual Transaxle

2009-05-19
2009-01-2064
Development of modern powertrains used in car and truck applications is more competitive than ever before. Powertrains and components previously considered to be advanced technology, such as hybrids and dual-clutch transmission technology, are now commonplace, being designed and manufactured in all worldwide markets. In order to stay competitive, powertrain OEMs must simultaneously optimize attributes such as performance, cost, weight, durability, fuel economy and NVH while producing new, desirable designs with reduced product development timelines. Oftentimes, the ideal solution for optimization of gear whine will result in an unexpected deterioration of durability, and vice versa. An advanced software tool was previously developed for the design of transmissions and transaxles, including analysis of the vibration, efficiency and durability performance under specified speeds and loads.
Technical Paper

Modeling, Validation and Analysis of the Fuel Supply and Injection System for NVH Improvement

2009-05-19
2009-01-2055
In the powertrain development of an automobile, the accurate prediction and understanding of the fuel supply and injection system behavior is necessary to achieve the targeted vehicle performance. With stronger demand from the customers for quieter vehicles, complementary functional objectives have to be met such as packaging, component or material change, or the modification of the fuel supply system layout. Understand the possible sources of noise and vibration from the fuel supply and delivery system requires having an analytical model of a complete fuel system, from the fuel pump assembly to the injectors. One has to note that adequate level of component details is required for the modeling and validation. In this study, the lumped-parameter model approach of the fluid dynamics on the fuel supply and delivery system has been developed and validated with the test results.
Technical Paper

Modeling, Design and Validation of an Exhaust Muffler for a Commercial Telehandler

2009-05-19
2009-01-2047
This paper describes the design, development and validation of a muffler for reducing exhaust noise from a commercial tele-handler. It also describes the procedure for modeling and optimizing the exhaust muffler along with experimental measurement for correlating the sound transmission loss (STL). The design and tuning of the tele-handler muffler was based on several factors including overall performance, cost, weight, available space, and ease of manufacturing. The analysis for predicting the STL was conducted using the commercial software LMS Virtual Lab (LMS-VL), while the experimental validation was carried out in the laboratory using the two load setup. First, in order to gain confidence in the applicability of LMS-VL, the STL of some simple expansion mufflers with and without extended inlet/outlet and perforations was considered. The STL of these mufflers were predicted using the traditional plane wave transfer matrix approach.
Journal Article

Prediction of Muffler Insertion Loss by a Hybrid FE Acoustic-SEA Model

2009-05-19
2009-01-2042
A reactive aftermarket automotive style muffler was considered for development and validation of a procedure to numerically predict and experimentally validate acoustic performance. A CAD model of the silencer was created and meshed. The silencer interior included two sections of perforated pipe, which were included in the cavity mesh. A hybrid FE-SEA (Statistical Energy Analysis) numerical model consisting of a finite element acoustic cavity excited by a diffuse acoustic field at the inlet and coupled via hybrid junctions to SEA semi-infinite fluids on both the inlet and outlet. The hybrid FE-SEA model solves very rapidly on a desktop PC making iterative numerical design a realistic option. To validate the predictions, an experimental setup was created to directly measure the muffler insertion loss. This was done by using a broadband acoustic source piped into a hemi-anechoic chamber.
Technical Paper

Boundary Conditions Affecting Gear Whine of a Gearbox Housing Acting as a Structural Member

2009-05-19
2009-01-2031
Vehicle cabin gear whine levels have long been known to contribute to driver annoyance and perceptions of poor quality in passenger cars and trucks, as well as contributing to operator fatigue in helicopters and heavy machinery. For material handling vehicles, radiated gear whine not only influences annoyance and fatigue of operators, but also creates unwanted noise in the operational environment such as warehouses and plants. Upfront management of gear whine levels using predictive software tools is therefore critical for satisfactory design of gearboxes used in such applications. One challenge, however, is selecting the proper boundary conditions for modeling a gearbox acting as a load-bearing structural member used in the material handling vehicles.
Technical Paper

A Test-Based Procedure for the Identification of Rack and Pinion Steering System Parameters for Use In CAE Ride-Comfort Simulations

2009-05-19
2009-01-2090
Current CAE modeling and simulation techniques in the time domain allow, by now, very accurate prediction of many ride-comfort performances of the cars. Nevertheless, the prediction of the steering wheel rotation vibration excited by, for instance, wheel unbalance or asymmetric obstacle impact, often runs into the difficulty of modeling the steering line with sufficient accuracy. For a classic rack and pinion, hydraulic assisted steering line, one of the challenges is to model the complex and non linear properties - stiffness, friction and damping - of the rack-rack case system. This paper proposes a rack model, thought for easy implementation in complex multi-body models, and an identification procedure of its parameters, based on measurements, in the operational range of the wheel unbalance excitation. The measurements have been gathered by specific tests on the components and the test set-up is also shown here.
Technical Paper

Optimizing R&H and NVH Performances Early in the Design Process via Multi Body Simulation

2009-05-19
2009-01-2087
This paper presents a CAE based approach to accurately simulate and optimize Ride and Handling metrics. Because of the wide range of vehicle phenomena involved, across the variety of frequency ranges, it is essential that the vehicle model includes proper representation of the dynamic properties of the various subsystems (e.g. tires, steering, PT, etc.) Precise correlation between test and simulation for standalone vehicle components and systems is achieved by replicating in the MBS (Multi-body Simulation) the same tests and boundary conditions. This allows the analyst to correctly define those crucial elements and parameters which have the greatest effect on the R&H attribute to be investigated. Setting up the simulation to correctly represent only one single maneuver simulation at a time would not allow the analyst to consider how the dynamic properties of the chassis design variables should be tuned to achieve to best balance and trade-offs.
Technical Paper

High Frequency Brake Squeal Prediction Index for Disc In-plane Mode

2009-05-19
2009-01-2102
As well as performance and safety, sensibility factor such as brake squeal noise has become an important factor to consider in today’s automotive industry. However, regardless of its importance, reduction of brake squeal noise has remained as one of the biggest challenges that have not yet been solved. Recently, many studies are being conducted to reduce squeal noise with the development of numerical analysis using FEM(Finite Element Method). This paper deals with complex eigenvalue analysis with commercial software program ABAQUS to resolve the squeal noise related to disc in-plane mode which is reported to occur frequently in the squeal noise frequency band 1~20kHz. As the reliability of the FE model is the most critical factor in numerical analysis, the FE model is first correlated with FRF modal test of each brake part and measurement of material property of pad with the anisotropic character through ultrasonic methods.
Technical Paper

Virtual and Physical Testing for Design Engineering of Intelligent Vehicles

2009-01-21
2009-26-0065
The increasing contribution of electronic and mechatronic content to the vehicle value requires rethinking the vehicle design and engineering processes. The present paper describes an approach hereto, based on virtual and physical prototype testing of heterogeneous systems. A key element is the integration between 3D geometry-Based Models (FE, MBS) and 1D multi-physics system-theoretic models for simulating complex devices (hydraulics, actuators, specific sensors) and processes (combustion, thermal, flow). Embedding control laws paves the way to Model-ln-the-Loop (MIL) and Software-In-the-Loop (SIL) concepts. By linking the virtual models to hardware systems on a physical test-bench, the static and dynamic performance of the rest of the vehicle system (suspension, body…) can be represented, enabling “Hardware in the Loop testing” (HIL). The “Vehicle-in-the-Loop” (VIL) validation finally allows the evaluation of all system dependencies and system interconnections.
Technical Paper

CAE Analysis of Dynamic Stiffness and NTF of Exhaust Attachment Point for NVH Improvement

2009-01-21
2009-26-0062
Dynamic stiffness at vehicle attachment points like powertrain, suspension or exhaust significantly affect excitations being transferred from respective sources to vehicle structure, which in turn affect the NVH performance. Simulation tools can be used to predict and improve attachment location dynamic stiffness and Noise Transfer Function (NTF). In this paper a case study on the influence of improvement in dynamic stiffness of exhaust attachment point to improve NTF is presented. Correlation of predicted results with test results and design solution through simulation has been developed to improve NTF performance. This was corroborated by experimental results too. The results show that higher dynamic stiffness will generally lead to better NTF, which is a measure of sensitivity to excitation at any attachment location and resulting in cab noise.
Technical Paper

Squeak and Rattle Prevention in the Design Phase Using a Pragmatic Approach

2009-01-21
2009-26-0051
Squeaks and Rattles (S&R) today are one of the main issues leading to a down ranking in quality perception of interiors in vehicles. Being annoyed by these types of noises, customers are driving up warranty and goodwill cost to many billion per vehicle model on lifetime. Still most of the problems are solved by automotive manufacturers and suppliers after they appear in hardware testing. Usually expensive solutions like felts and oil/grease are selected to solve the problem. However prevention is the key to eliminate unwanted Squeaks and Rattles early in the design phase based on CAD data and material information. This paper shows a pragmatic approach to support the design engineer to create a virtually S&R free CAD-model.
Technical Paper

CAE Techniques for System Analysis of Hypoid Gearset Vibration

2011-05-17
2011-01-1502
Traditionally, the development of automotive drivelines incorporating hypoid or spiral bevel gearing using Computer Aided Engineering (CAE) methods have included the analysis of gear contact patterns independent of the influence of the flexible members of the driveline such as the housing and shafting. The gear tooth form development typically occurs using various non-linear gear contact solutions available on the market, but the final refinement of the gear itself usually must wait until the actual hardware can be fabricated and tested in the driveline system. This behavior may result in several costly and time consuming iterations of testing, modifying, and re-testing a gearset, since the up-front CAE tools did not account for the flexibility of the driveline system, nor factors such as bearing pre-load effects, thermal growth, driveline torque levels, dynamic modes of the shafting, and many other important factors.
Technical Paper

A Study on Improvement of Indicated Thermal Efficiency of ICE Using High Compression Ratio and Reduction of Cooling Loss

2011-08-30
2011-01-1872
Improvement of indicated thermal efficiency of internal combustion engines is required, and increasing the compression ratio is an effective solution. In this study, using a CAE analysis coupling a 0-dimensional combustion analysis and a 1-dimensional heat conduction analysis, the influence of compression ratio on indicated thermal efficiency and combustion was investigated. As a result, it was found that there was an optimal compression ratio that gave the best indicated thermal efficiency, because the increase of cooling loss caused by high compression was bigger than the increase of theoretical indicated thermal efficiency in some cases. Next, the influence of cooling loss reduction on the optimal compression ratio was investigated. It was found that indicated thermal efficiency improved by reducing cooling loss, because the compression ratio which made the best indicated thermal efficiency was shifted to higher compression ratio.
Technical Paper

Door Check Load Durability - Fatigue Life Prediction

2011-04-12
2011-01-0790
This paper describes an analytical methodology for predicting the fatigue life of a door system for check load durability cycles. A check stop load durability cycle occurs when a customer opens the door beyond the door detent position with a force applied on the check link or hinge check stops. This method combines Finite Element Analysis (FEA) model and fatigue code to compute the durability requirements. The FEA model consists of Door-in-White (DIW) on body with integrated hinge check link or independent check link. Nonlinear material, geometric and parts contact were considered for the door with body-in-white (BIW). Several door hinge designs, with integrated and independent check links, were investigated. Using the Von Mises stress and plastic strain from the above analysis, the fatigue life was predicted and compared with the test data. Integrating FEA and fatigue allows predicting the threshold total strain value, which is developed, for check load durability requirements.
Technical Paper

CAE based ‘Multi Objective Optimization approach for Spot Weld Connections Layout’ in Automotive Structure

2011-04-12
2011-01-0794
Spot weld connections are used extensively in the automotive industry to join panels of automotive structures. Spot weld connections play a very vital role in the overall structural rigidity and integrity of the Body in White. The spot weld connections and layout have direct impact on functionability of automotive structure and capital investment for robots, guns and operators. There is continuous pressure on automotive engineers to reduce the number of spot weld connections in a structure without compromising on the structural performance across various disciplines such as crash, NVH & durability. Hence the need is felt to develop a generic and systematic CAE simulation procedure which will guide the designer towards arriving at an optimum design, with minimum number of spot weld connections, which meet all the performance requirements of the structure.
Technical Paper

Enhanced Error Assessment of Response Time Histories (EEARTH) Metric and Calibration Process

2011-04-12
2011-01-0245
Computer Aided Engineering (CAE) has become a vital tool for product development in automotive industry. Increasing computer models are developed to simulate vehicle crashworthiness, dynamic, and fuel efficiency. Before applying these models for product development, model validation needs to be conducted to assess the validity of the models. However, one of the key difficulties for model validation of dynamic systems is that most of the responses are functional responses, such as time history curves. This calls for the development of an objective metric which can evaluate the differences of both the time history and the key features, such as phase shift, magnitude, and slope between test and CAE curves. One of the promising metrics is Error Assessment of Response Time Histories (EARTH), which was recently developed. Three independent error measures that associated with physically meaningful characteristics (phase, magnitude, and slope) were proposed.
Technical Paper

Development of Robust CAE Modeling Technique for Decklid Slam Analysis

2011-04-12
2011-01-0242
Engineering has continuously strived to improve the vehicle development process to achieve high quality designs and quick to launch products. The design process has to have the tools and capabilities to help ensure both quick to the market product and a flawless launch. To achieve high fidelity and robust design, mistakes and other quality issues must be addressed early in the engineering process. One way to detect problems early is to use the math based modeling and simulation techniques of the analysis group. The correlation of the actual vehicle performance to the predictive model is crucial to obtain. Without high correlation, the change management process begins to get complicated and costs start to increase exponentially. It is critical to reduce and eliminate the risk in a design up front before tooling begins to kick off. The push to help achieve a high rate of correlation has been initiated by engineering management, seeing this as an asset to the business.
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