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In recent years, Nearfield Acoustical Holography (NAH) has been used to identify stationary vehicle exterior noise sources. However that application has usually been limited to individual components. Since powertrain noise sources are hidden within the engine compartment, it is difficult to use NAH to identify those sources and the associated partial field that combine to create the complete exterior noise field of a motor vehicle. Integrated Nearfield Acoustical Holography (INAH) has been developed to address these concerns: it is described here. The procedure entails sensing the sources inside the engine compartment by using an array of reference microphones, and then calculating the associated partial radiation fields by using NAH. In the second part of this paper, the use of farfield arrays is considered. Several array techniques have previously been applied to identify noise sources on moving vehicles.

Although soot-formation processes in diesel engines have been well characterized during the mixing-controlled burn, little is known about the distribution of soot throughout the combustion chamber after the end of appreciable heat release during the expansion and exhaust strokes. Hence, the laser-induced incandescence (LII) diagnostic was developed to visualize the distribution of soot within an optically accessible single-cylinder direct-injection diesel engine during this period. The developed LII diagnostic is semi-quantitative; i.e., if certain conditions (listed in the Appendix) are true, it accurately captures spatial and temporal trends in the in-cylinder soot field. The diagnostic features a vertically oriented and vertically propagating laser sheet that can be translated across the combustion chamber, where “vertical” refers to a direction parallel to the axis of the cylinder bore.

During development of an air assisted, direct injection combustion system, it was found that an air pulse during the late part of compression stroke significantly shortened the combustion duration and extended the lean limits of the engine. The effect of an injection of pure air through an air assist direct injector was studied with Particle Image Velocimetry, PIV. Results showed that an air pulse during the compression stroke significantly speeded up in-cylinder velocities, which also was showed in the heat release analysis. A system to use low density seeding particles was developed and is presented in the paper.

A noticeable degree of inconsistent forming behaviors has been observed for the 1st generation advanced high strength steels (AHSS) in production, and they appear to be associated with the inherent microstructural-level inhomogeneities for various AHSS. This indicates that the basic material property requirements and screening methods currently used for the mild steels and high strength low alloys (HSLA) are no longer sufficient for qualifying today's AHSS. In order to establish more relevant material acceptance criteria for AHSS, the fundamental understandings on key mechanical properties and microstructural features influencing the local formability of AHSS need to be developed. For this purpose, in this study, DP980 was selected as model steels and eight different types of DP980 sheet steels were acquired from various steel suppliers.

Engineering new technology and products challenges managers to balance design innovation and program risk. To do this, managers need methods to judge future results to avoid program and product disasters. Besides the traditional prediction tools of schedule, simulations and “iron tests”, process control standards (with measurements) can also be applied to the development programs to mitigate risks. This paper briefly discusses the theory and case history behind some new process control methods and standards currently in place at Caterpillar's Electrical & Electronics department. Process standards reviewed in this paper include process mapping, ISO9001, process controls, and process improvement models (e.g. SEI's CMMs.)

Microstructure level inhomogeneities between the harder martensite phase and the softer ferrite phase render the dual phase (DP) steels more complicated failure mechanisms and associated failure modes compared to the conventionally used low alloy homogenous steels. This paper examines the failure mode DP780 steel under different loading conditions using finite element analyses on the microstructure levels. Micro-mechanics analyses based on the actual microstructures of DP steel are performed. The two-dimensional microstructure of DP steel was recorded by scanning electron microscopy (SEM). The plastic work hardening properties of the ferrite phase was determined by the synchrotron-based high-energy X-ray diffraction technique. The work hardening properties of the martensite phase were calibrated and determined based on the uniaxial tensile test results. Under different loading conditions, different failure modes are predicted in the form of plastic strain localization.

Smaller locomotives often use mechanical transmissions instead of diesel-electric drive systems typically used in larger locomotives. This paper discusses how Model Based Design was used to develop the complete drive train control system for a 24 ton sugar cane locomotive. A complete MATLAB Simulink machine model was built to fully test and verify the shift control logic, traction control, vehicle speed limiting, and braking control for this locomotive application before it was commissioned. The model included the engine, torque converter, planetary transmission, drive line, and steel on steel driving surface. Simulation was used to debug all control code and test and refine control strategies so that the initial field commissioning in remote Australia was executed very quickly with minimal engineering support required.

In this paper, the microstructure-based finite element modeling method is used in investigating the loading path dependence of formability of transformation induced plasticity (TRIP) steels. For this purpose, the effects of different loading path on the forming limit diagrams (FLD) of TRIP steels are qualitatively examined using the representative volume element (RVE) of a commercial TRIP800 steel. First, the modeling method was introduced, where a combined isotropic/kinematic hardening rule is adopted for the constituent phases in order to correctly describe the cyclic deformation behaviors of TRIP steels during the forming process with combined loading paths which may include the unloading between the two consecutive loadings. Material parameters for the constituent phases remained the same as those in the authors' previous study [ 1 ] except for some adjustments for the martensite phase due to the introduction of the new combined hardening rule.

Laser-Rayleigh imaging has been employed to measure the relative fuel concentration in the gaseous jet region of DME sprays. The measurements were performed in an optically accessible diesel truck engine equipped with a common rail injection system. A one-hole nozzle was used to guarantee that the recorded pressure history was associated with the heat release in the imaged spray. To compensate for the low compression ratio in the modified engine the inlet air was preheated. Spray development was studied for two levels of preheating, from the start of injection to the point where all fuel was consumed. The results indicate that there is a strong correlation between the amount of unburned fuel present in the cylinder and the rate of heat release at a given time. The combustion can not be described as purely premixed or purely mixing-controlled at any time, but always has an element of both. After all fuel appears to have vanished there is still an extended period of heat release.

This paper presents results from a quantitative characterization of the NO distribution in a SI engine fueled with a stoichiometric iso-octane/air mixture. Different engine operating conditions were investigated and accurate results on NO concentrations were obtained from essentially the whole cylinder for crank angle ranges from ignition to the mid expansion stroke. The technique used to measure the two-dimensional NO concentration distributions was laser induced fluorescence utilizing a KrF excimer laser to excite the NO A-X (0,2) bandhead. Results were achieved with high temporal and spatial resolution. The accuracy of the measurements was estimated to be 30% for absolute concentration values and 20% for relative values. Images of NO distributions could also be used to evaluate the flame development. Both the mean and the variance of a combustion progress variable could be deduced.

To study the effect of different injection timings on the charge inhomogeneity, planar laser-induced fluorescence (PLIF) was applied to an operating engine. Quantitative images of the fuel distribution within the engine were obtained. Since the fuel used, iso-octane, does not fluoresce, a dopant was required. Three-pentanone was found to have vapour pressure characteristics similar to those of iso-octane as well as low absorption and suitable spectral properties. A worst case estimation of the total accuracy from the PLIF images gives a maximum error of 0.03 in equivalence ratio. The results show that an early injection timing gives a higher degree of charge inhomogeneity close to the spark plug. It is also shown that charge inhomogeneity gives a more unstable engine operation. A correlation was noted between the combustion on a cycle to cycle basis and the average fuel concentration within a circular area close to the spark plug center.

This paper presents development of a multi-scale material model for a 980 MPa grade transformation induced plasticity (TRIP) steel, subject to a two-step quenching and partitioning heat treatment (QP980), based on integrated computational materials engineering principles (ICME Model). The model combines micro-scale material properties defined by the crystal plasticity theory with the macro-scale mechanical properties, such as flow curves under different loading paths. For an initial microstructure the flow curves of each of the constituent phases (ferrite, austenite, martensite) are computed based on the crystal plasticity theory and the crystal orientation distribution function. Phase properties are then used as an input to a state variable model that computes macro-scale flow curves while accounting for hardening caused by austenite transformation into martensite under different straining paths.

The induction hardening process involves a complex interaction of electromagnetic heating, rapid cooling, metallurgical phase transformations, and mechanical behavior. Many factors including induction coil design, power, frequency, scanning velocity, workpiece geometry, material chemistry, and quench severity determine a process outcome. This paper demonstrates an effective application of a numerical analysis tool for understanding of induction hardening. First, an overview of the Caterpillar induction simulation tool is briefly discussed. Then, several important features of the model development are examined. Finally, two examples illustrating the use of the computer simulation tool for solving induction-hardening problems related to cracking and distortion are presented. These examples demonstrate the tool's ability to simulate changes in process parameters and latitude of modeling steel or cast iron.

High-speed laser diagnostics was utilized for single-cycle resolved studies of the formaldehyde distribution in the combustion chamber of an HCCI engine. A multi-YAG laser system consisting of four individual Q-switched, flash lamp-pumped Nd:YAG lasers has previously been developed in order to obtain laser pulses at 355 nm suitable for performing LIF measurements of the formaldehyde molecule. Bursts of up to eight pulses with very short time separation can be produced, allowing capturing of LIF image series with high temporal resolution. The system was used together with a high-speed framing camera employing eight intensified CCD modules, with a frame-rate matching the laser pulse repetition rate. The diagnostic system was used to study the combustion in a truck-size HCCI engine, running at 1200 rpm using n-heptane as fuel. By using laser pulses with time separations as short as 70 μs, cycle-resolved image sequences of the formaldehyde distribution were obtained.

High-speed video imaging in a swirl-supported (Rs = 1.7), direct-injection heavy-duty diesel engine operated with moderate-to-high EGR rates reveals a distinct correlation between the spatial distribution of luminous soot and mean flow vorticity in the horizontal plane. The temporal behavior of the experimental images, as well as the results of multi-dimensional numerical simulations, show that this soot-vorticity correlation is caused by the presence of a greater amount of soot on the windward side of the jet. The simulations indicate that while flow swirl can influence pre-ignition mixing processes as well as post-combustion soot oxidation processes, interactions between the swirl and the heat release can also influence mixing processes. Without swirl, combustion-generated gas flows influence mixing on both sides of the jet equally. In the presence of swirl, the heat release occurs on the leeward side of the fuel sprays.

The transportation industry is finding an ever-increasing number of applications for products manufactured using the tubular hydroforming process. Most of the current hydroforming applications use steel tubes. However, with the mounting regulatory pressure to reduce vehicle emissions, aluminum alloys appear attractive as an alternative material to reduce vehicle weight. The introduction of aluminum alloys to tubular hydroforming requires knowledge of their forming limits. The current work investigates the forming limits of AA6061 in both the T4 and T6 tempers under laboratory conditions. These experimental results are compared to theoretical forming limit diagrams calculated via the M-K method. Free hydroforming results and forming limit diagrams are also compared to components produced under commercial hydroforming conditions.

Two-dimensional cycle-resolved burnt gas temperatures were measured using two line atomic fluorescence (TLAF) in a single cylinder spark ignition car engine. Mapping of the in-cylinder flow was done under the same operating conditions using Particle Imaging Velocimetry (PIV). Experimental data for temperature and flow was compared to results from numerical simulations.

This paper examines some key aspects of the manufacturing process that “ Transformation Induced Plasticity” (TRIP) steels would be exposed to, and systematically evaluate how the forming and thermal histories affect final strength and ductility of the material. We evaluate the effects of in-service temperature variations, such as under hood and hot/cold cyclic conditions, to determine whether these conditions influence final strength, ductility and energy absorption characteristics of several available TRIP steel grades. As part of the manufacturing thermal environment evaluations, stamping process thermal histories are included in the studies. As part of the in-service conditions, different pre-straining levels are included. Materials from four steel suppliers are examined. The thermal/straining history versus material property relationship is established over a full range of expected thermal histories and selected loading modes.

This paper examines the effects of fusion zone size on failure modes, static strength and energy absorption of resistance spot welds (RSW) of advanced high strength steels (AHSS). DP800 and TRIP800 spot welds are considered. The main failure modes for spot welds are nugget pull-out and interfacial fracture. Partial interfacial fracture is also observed. The critical fusion zone sizes to ensure nugget pull-out failure mode are developed for both DP800 and TRIP800 using the limit load based analytical model and the microhardness measurements of the weld cross sections. Static weld strength tests using cross-tension samples were performed on the joint populations with controlled fusion zone sizes. The resultant peak load and energy absorption levels associated with each failure mode were studied using statistical data analysis tools. The results of this study show that the conventional weld size of can not produce nugget pull-out mode for both the DP800 and TRIP800 materials.

In this paper, results of finite element crash simulation are presented for a TRIP steel side rail with and without considering the phase transformation during forming operations. A homogeneous phase transformation model is adapted to model the mechanical behavior of the austenite-to-martensite phase. The forming process of TRIP steels is simulated with the implementation of the material model. The distribution and volume fraction of the martensite in TRIP steels may be greatly influenced by various factors during forming process and subsequently contribute to the behavior of the formed TRIP steels during the crushing process. The results indicate that, with the forming induced phase transformation, higher energy absorption of the side rail can be achieved. The phase transformation enhances the strength of the side rail.