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The conflicting requirements of better fuel economy, higher performance and lower emissions from an automobile engine have brought many new challenges that require development teams to look beyond conventional test and seek answers from simulations. One of the relatively unexplored areas of development where frictional losses haven't been completely understood is the flow in the crankcase. Here computational engineering can play a significant role in analyzing flow field in a hidden and complex region where otherwise testing has serious limitations. Flow simulation in the crankcase poses significant complexity and provides an opportunity to enhance the understanding of underlying physics by using multi-physics analyses tools available commercially. In this study, air space under the piston and above the oil level in oil pan is simulated. It is known that bay-to-bay breathing and windage holes account for considerable amount of power losses in the crankcase.

This paper discusses CAE simulation methods to predict the thermal induced buckling issues when vehicle body panels are subjected to the elevated temperature in e-coat oven. Both linear buckling analysis and implicit quasi-static analysis are discussed and studied using a quarter cylinder shell as an example. The linear buckling analysis could produce quick but non-conservative buckling temperature. With considering nonlinearity, implicit quasi-static analysis could predict a relative conservative critical temperature. In addition, the permanent deformations could be obtained to judge if the panel remains visible dent due to the buckling. Finally these two approaches have been compared to thermal bucking behavior of a panel on a vehicle going through thermal cycle of e-coat oven with the excellent agreement on its initial design and issue fix design. In conclusion, the linear buckling analysis could be used for quick thermal buckling evaluation and comparison on a series of proposals.

The use of signature analysis to determine the acceptability of parts in a production line quality control situation is highly desirable. Specifically, the use of acoustic signature analysis is attractive due to the relaxed constraints in terms of fixturing the part in preparation for analysis. This study discusses techniques presently being investigated which rely on knowledge of the modal coefficients to direct the area of investigation.

With the implementation of digital signal processing, frequency response measurements are not limited to swept sine testing. With the discrete Fourier Transform, any physically realizable signal can be used for excitation. The best technique depends on the application, available equipment, the presence of measurement noise, the linearity of the test object, and the time available in which to execute the test. In this paper a number of excitation techniques have been described. All of these techniques have advantages and disadvantages which have been described in the text of this paper.

In an automotive air-conditioning (AC) system, the amount of work done by the compressor is also influenced by the suction line which meters the refrigerant flow. Optimizing the AC suction line routing has thus become an important challenge and the plumbing designers are required to come up with innovative packaging solutions. These solutions are required in the early design stages when prototypes are not yet appropriate. In such scenarios, one-dimensional (1D) simulations shall be employed to compute the pressure drop for faster and economical solution. In this paper, an approach of creating a modeling tool for suction line pressure drop prediction is discussed. Using DFSS approach L12 design iterations are created and simulations are carried out using 1D AMESim software. Prototypes are manufactured and tested on HVAC bench calorimeter. AC suction line pressure drop predicted using the 1D modeling co-related well with the test data and the error is less than 5%.

Reliable testing of a mechanical system requires the procedures used for the evaluation to be repeatable and reproducible. However, it is never possible to exactly repeat or reproduce the tests that are used for evaluation. To overcome this limitation, a statistical evaluation procedure can generally be used. However, most of the statistical procedures use scalar values as input without the ability to handle vectors or time-histories. To overcome these limitations, two numerical/statistical methods for determining if the impact time-history response of a mechanical system is repeatable or reproducible are evaluated and elaborated upon. Such a system could be a vehicle, a biological human surrogate, an Anthropometric Test Device (ATD or dummy), etc. The responses could be sets of time-histories of accelerations, forces, moments, etc., of a component or of the system. The example system evaluated is the BioRID II rear impact dummy.

Surge is a phenomenon that limits the operational range of the compressor at low mass flow rates. The objective of this research is to study effective operational range for a ported shroud compressor. The size of the compressor is typical for a turbocharger used on diesel engines. To be able to extend the operational range, the surge characteristics have to be assessed. This is done by performing measurement of the flow at the inlet to the compressor wheel and pressure fluctuations at the inlet and outlet of the compressor housing. Detailed numerical computations of the flow in the entire compressor section under similar operating conditions have also been carried out. The experimental work includes Particle Imaging Velocimetry (PIV) measurements of the instantaneous and mean velocity field at the inlet. At surge, low frequency pulsations are detected that seem to result from back flow already observed in stall.

The benefits of utilizing virtual engineering include not only shortened product development time and reduced reliance on expensive physical testing, but also the opportunities for greater standardization to support higher product quality. This paper describes a project for building a smart meshing template with a CAD/CAE link. The objective of the project is to optimize the utilization of CAD software and CAE preprocessing software capabilities. The deliverable of the project is a cylinder head mesh template which meets all the cylinder head durability simulation meshing requirements, and which links to CAD/CAE software. Special surface areas identified are built into the cylinder head CAD model design. By using one of the features in CAD software, all the special surfaces can be automatically updated throughout the design process.

In this paper, the development of random vibration testing schedules for durability design verification of engine mounted products is presented, based on the equivalent fatigue damage concept and the 95th-percentile customer engine usage data for 150,000 miles. Development of the 95th-percentile customer usage profile is first discussed. Following that, the field engine excitation and engine duty cycle definition is introduced. By using a simplified transfer function of a single degree-of-freedom (SDOF) system subjected to a base excitation, the response acceleration and stress PSDs are related to the input excitation in PSD, which is the equivalent fatigue damage concept. Also, the narrow-band fatigue damage spectrum (FDS) is calculated in terms of the input excitation PSD based on the Miner linear damage rule, the Rayleigh statistical distribution for stress amplitude, a material's S-N curve, and the Miles approximate solution.

This book, written for practicing engineers, designers, researchers, and students, summarizes basic vibration theory and established methods for analyzing vibrations. Principles of Vibration Analysis goes beyond most other texts on this subject, as it integrates the advances of modern modal analysis, experimental testing, and numerical analysis with fundamental theory. No other book brings all of these topics together under one cover. The authors have compiled these topics, compared them, and provided experience with practical application. This must-have book is a comprehensive resource that the practitioner will reference time and again.

With the advent of quieter powertrain and improved cabin acoustic sealing, there is an increased focus on noise generated in the HVAC unit and climate control ducting system. With improved insulation from exterior noise sources such as wind & road noise, HVAC noise is more perceptible by the occupants and is a key quality indicator for new generation vehicles. This has increased the use of simulations tools to predict HVAC noise during the virtual development phase of new vehicle programs. With packaging space being premium under the instrument panel, changes to address noise issues are expensive and often impractical. The current methodology includes the best practices in simulation accumulated from prior aero acoustics validation studies on fans, ducts, flaps and plenum volume discharge. The paper details the acoustic noise generation and propagation in the near field downstream of an automotive HVAC unit in conjunction with ducting system.

The sound quality of a prototype series hydraulic hybrid passenger vehicle powertrain was analyzed. Different sound quality metrics were evaluated to determine which one correlated best with the subjective assessment of sound quality, and a desired sound quality target was developed. Next, the effect of the design of the hydraulic powertrain components on sound quality was analyzed. Two extreme options were analyzed: “stiff” systems with a hard drive shaft or short fluid hoses, and “soft” systems with a soft drive shaft or long fluid hoses. Experimental results from these systems are presented in the paper. Finally, design recommendations were made to achieve the best sound quality of the hybrid hydraulic powertrain, and therefore maximum customer satisfaction.

Taguchi method is a technology to prevent quality problems at early stages of product development and product design. Parameter design method is an important part in Taguchi method which selects the best control factor level combination for the optimization of the robustness of product function against noise factors. The air induction system (AIS) provides clean air to the engine for combustion. The noise radiated from the inlet of the AIS can be of significant importance in reducing vehicle interior noise and tuning the interior sound quality. The porous duct has been introduced into the AIS to reduce the snorkel noise. It helps with both the system layout and isolation by reducing transmitted vibration. A CAE simulation procedure has been developed and validated to predict the snorkel noise of the porous ducted AIS. In this paper, Taguchi's parameter design method was utilized to optimize a porous duct design in an AIS to achieve the best snorkel noise performance.

Traditional warm forming of aluminum refers to sheet forming in the temperature range of 200°C to 350°C using heated, matched die sets similar to conventional stamping. While the benefits of this process can include design freedom, improved dimensional capability and potentially reduced cycle times, the process is complex and requires expensive, heated dies. The objective of this work was to develop a warm forming process that both retains the benefits of traditional warm forming while allowing for the use of lower-cost tooling. Enhanced formability characteristics of aluminum sheet have been observed when there is a prescribed temperature difference between the die and the sheet; often referred to as a non-isothermal condition. This work, which was supported by the USCAR-AMD initiative, demonstrated the benefits of the non-isothermal warm forming approach on a full-scale door inner panel. Finite element analysis was used to guide the design of the die face and blank shape.

Road-tire induced vibrations are in many vehicles determining the interior noise levels in (semi-) constant speed driving. The understanding of the noise contributions of different connections of the suspension systems to the vehicle is essential in improvement of the isolation capabilities of the suspension- and body-structure. To identify these noise contributions, both the forces acting at the suspension-to-body connections points and the vibro-acoustic transfers from the connection points to the interior microphones are required. In this paper different approaches to identify the forces are compared for their applicability to road noise analysis. First step for the force identification is the full vehicle operational measurement in which target responses (interior noise) and indicator responses (accelerations or other) are measured.

During component development of multiple fastener bolted joints, it was observed that one or two fasteners had a higher potential to slip when compared to other fasteners in the same joint. This condition indicated that uneven distribution of the service loads was occurring in the bolted joints. The need for an optimization tool was identified that would take into account various objectives and constraints based on real world design conditions. The objective of this paper is to present a method developed to determine optimized multiple fastener locations within a bolted joint for achieving evenly distributed loads across the fasteners during multiple load events. The method integrates finite element analysis (FEA) with optimization software using multi-objective optimization algorithms. Multiple constraints were also considered for the optimization analysis. In use, each bolted joint is subjected to multiple service load conditions (load cases).

Using gasoline and diesel simultaneously in a dual-fuel combustion system has shown effective benefits in terms of both brake thermal efficiency and exhaust emissions. In this study, the dual-fuel approach is applied to a light-duty spark ignition (SI) gasoline direct injection (GDI) engine. Three combustion modes are proposed based on the engine load, diesel micro-pilot (DMP) combustion at high load, SI combustion at low load, and diesel assisted spark-ignition (DASI) combustion in the transition zone. Major focus is put on the DMP mode, where the diesel fuel acts as an enhancer for ignition and combustion of the mixture of gasoline, air, and recirculated exhaust gas. Computational fluid dynamics (CFD) is used to simulate the dual-fuel combustion with the final goal of supporting the comprehensive optimization of the main engine parameters.

Superior NVH performance is a key focus in the development of new powertrains. In recent years, computer simulations have gained an increasing role in the design, development, and optimization of powertrain NVH at component and system levels. This paper presents the results of a study carried out on a 4-cylinder in-line spark-ignition engine with focus on growl noise. Growl is a low frequency noise (300-700 Hz) which is primarily perceived at moderate engine speeds (2000-3000 rpm) and light to moderate throttle tip-ins. For this purpose, a coupled and fully flexible multi-body dynamics model of the powertrain was developed. Structural components were reduced using component mode synthesis and used to determine dynamics loads at various engine speeds and loading conditions. A comparative NVH assessment of various crankshaft designs, engine configurations, and in- cylinder gas pressures was carried out.

Most manufacturing and assembly processes like stamping, clamping, interference fits introduce a pre-stress condition in components or assemblies. Very often these stresses are high enough and alter the mean stress state resulting in significant effect on fatigue life performance and thus cannot be ignored. If the pre-stress is compressive, it will increase the allowable stress range and improve fatigue life performance; on the other hand if these stresses are tensile, they will decrease the allowable stress range resulting in a degradation of fatigue life. At times it becomes critical to effectively introduce the pre-stress condition in order to accurately represent the stress state in an FEA based durability simulation. Accounting for the pre-stress state in FEA based constant amplitude loading fatigue life simulation is relatively straight forward, but when it comes to random variable amplitude multi-channel loads simulation, the problem becomes more complicated.

The complexity of both hardware and software has increased significantly in automotive over the past decade. This is apparent even in the compact passenger car market segment where the presence of electronic control units (ECU) has nearly tripled. In today's luxury vehicles, software can reach 100 million lines of code and are only projected to increase. Without preventive measures, the risk of safety-related system malfunction becomes unacceptably too high. The functional safety standard ISO 26262, released as first edition in 2011, provides crucial safety-related requirements for passenger vehicles. Although the standard defines the proper development for safety-related systems to ensure the avoidance of a hazard, it's implication for electromagnetic compatibility (EMC) is not clearly defined. This paper outlines the impact of ISO 26262 for EMC related issues, and discusses the standard's implications for EMC requirements on the present EMC practices for production vehicles.