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Welding induced residual stresses are an important factor to consider when evaluating fatigue design of welded automotive parts. Fortunately, design engineers have various residual stress mitigation technologies at their disposal for improving the fatigue performance of these parts. For this purpose, it is essential to understand the relationship between the residual stresses and fatigue performance quantitatively as well as qualitatively. It has been widely accepted that tensile residual stresses in welded structures are as high as the material yield strength level. Therefore, the fatigue strength of welded joints is governed predominantly by the applied stress range, regardless of the load ratio. However, in stress relieved components the tensile residual stress level is not as high, and the weld fatigue behavior is more influenced by the load ratio.

Even under uniaxial loading, seemingly simple welded joint types can develop multi-axial stress states, which must be considered when evaluating both the fatigue strength and failure location. Based on the investigation of fatigue behavior for the multi-axial stress state, a procedure for fatigue behavior of welded joints with multi-axial stress states was proposed using an effective equivalent structural stress range parameter combined normal and in-plane shear equivalent structural stress ranges and the master S-N curve approach. In automotive structures, fatigue failure is often observed at weld end, which often show a complex stress state. Due to simplified weld end representation having a sharp right-angled weld corner, the fatigue failure prediction at the weld end tends to be overly conservative due to the excessive stress concentration at the right-angled weld termination.

Lightweight, optimized vehicle designs are paramount in helping the automotive industry meet reduced emissions standards. Self-piercing rivets are a promising new technology that may play a role in optimizing vehicle designs, due to their superior fatigue resistance compared with spot welds and ability to join dissimilar materials. This paper presents a procedure for applying the mesh-insensitive Battelle Structural Stress Method to self-piercing riveted joints for fatigue life prediction. Additionally, this paper also examines the development of an interim fatigue design master S-N curve for self-piercing rivets. The interim fatigue design master S-N curve accounts for factors such as various combinations of similar and dissimilar metal sheets, various sheet thicknesses, stacking sequence, and load ratios. A large amount of published data was collapsed into a single interim S-N curve with reasonable data scattering.

Weld fatigue evaluation using the mesh-insensitive Battelle structural stress method has been applied to fusion welds, resistance spot welds and non-welded components. The effectiveness of the Battelle structural stress procedure has been demonstrated in a series of earlier publications for welded structures with different joint types, plate thicknesses, and loading modes. In this paper, a weld fatigue evaluation procedure using the Battelle structural stress method is proposed for friction stir welds currently being used in the automotive and aerospace industries. The applicability of the Battelle structural stress procedure is demonstrated by comparing fatigue life predictions for friction stir welded specimens to well-documented test data from the literature. Different specimen types, plate thicknesses and loading ratios were analyzed for several aluminum alloys.

Automotive industries in the US and around the world have enormous impact on the economy of each country. Not just the major vehicle manufacturer, but all the other companies in the supply chain are equally important. This was evident with the earthquake and Tsunami that happened in March 2011. Because of the massive destruction at suppliers' facilities, the automakers in the US and other countries struggled to get the necessary parts and supplies. This created a ripple effect throughout the world and led to the closure of several automakers' facilities for a long time. Thus, the automotive supply chains are as important as the main automotive manufacturing facilities. Since these suppliers produce a lot of parts and supplies, the corresponding energy usage is also significant. The current research is focused on compressed air and process heating system analysis at one of the automotive parts manufacturer in Mexico.

The nodal force based Battelle structural stress method has shown its mesh insensitivity in the stress analysis of spot welds as well as fusion welds. In the conventional structural stress simulation procedure, the structural stress is calculated at the nodes along the nugget periphery. However, implementing a nugget into each spot weld is cumbersome and time consuming not only in preparing mesh for FE analysis but also in preparing a series of structural stress calculation after finishing the FE analysis. Therefore, the efficiency of the current Battelle structural stress practice for spot welds can be improved significantly for structures with a large number of spot welds. The simplified modeling procedure presented here delivers reliable structural stresses at spot welds and these stresses can then be utilized for fatigue life prediction using a master S-N Curve approach that is applicable to wide range of spot welding techniques.

Recent advances in Metal Matrix Composites have made them ready for transition to large-volume production and commercialization. Such new materials seem to allow the fabrication of higher quality parts at less than 50 percent of the weight as compared to steel. The increasing requirements of weight savings and extended durability motivated the potential application of MMC technology into the heavy vehicle market. However, significant technical barriers such as joining are likely to hinder the broad applications of MMC materials in heavy vehicles. The focus of this paper is to examine the feasibility of manufacturing and the behavior of bolted joint connections made from aluminum matrix reinforced with Silicon Carbide (SiC) particles. Two reinforcement ratios: 20% and 45% were considered in this study. The first part of the paper concentrates on experimental evaluation of bolted MMC joints.

Tailor-welded blanks (TWB) have been increasingly used in the automotive industry as an effective way to reduce weight and costs. Although some of the joining processes for TWB are relatively well known, little independent information exists regarding welding procedure effects on weld/HAZ properties, particularly their effects on form-ability and structural performance under various conditions. In this paper, advanced computational modeling techniques were used to investigate the effects of welding procedures on weld property evolution and its impact on the formability issues. Two case studies were presented. One is on TIG welding of 6000 series aluminum tailored blanks, where thermomechanical effects on weldability was analyzed. Its implication on weld performance during forming will be discussed. The other case is on laser-beam welding of high strength steel to mild steel with a non-linear weld. The detailed thermal history and residual stress development will be presented.

In this study, an incrementally coupled finite element analysis procedure is used to analyze the electrical, thermal, and mechanical interaction during resistance spot welding processes. The results of the finite element analysis are validated by experimental measurements of the weld nugget sizes and dynamic resistance. The temperature results from the thermo-electric analysis are used as the input for the prediction of the microstructure evolution in the resistance spot welds of high strength steels. Consequently such welding parameters as welding current, electrode force, electrode designs, cooling water temperature and flow rate, and electrode holding time can be linked with the weld nugget size, microstructure and mechanical properties in spot welds, and eventually the residual stresses and performance of spot welded structures.

The effects of electrode wear on nugget development during resistance spot welding are major concerns in auto-body assembly and manufacturing. By considering detailed electrode-sheet interactions using advanced finite element modeling procedure, this paper presents a framework for detecting the electrode wear conditions and associated nugget development characteristics. Two important in-process parameters are studied in detail. They are the electrode movement and the dynamic resistance. It is found that the second-order derivative of the electrode movement and the first-order derivative of the dynamic resistance can be correlated in a fundamental form to identify the detailed nugget development process under various electrode wear conditions.

This paper presents results from a study on speciation of the emission profiles and on the ozone forming potential of heavy-duty diesel exhaust under steady state engine operation. Very limited attempts have been made at determining the ozone forming potential of heavy duty diesel exhaust emissions. In this study a proportional sample of the dilute exhaust was drawn from a CFV-CVS system using a temperature controlled sampling line. The particulate matter was collected on a 70 mm Teflon coated glass fiber filter (TX40HI20WW), the semi-volatiles on XAD-2 copolymer resin and volatiles in Tedlar bags. The samples were analyzed by gas chromatography after conditioning and chemical extractions. The initial phase of the study was directed towards developing techniques and establishing protocols to determine the ozone forming potential of heavy-duty diesel exhaust. A pre-chamber naturally aspirated engine was tested on steady-state modes 1, 3, 5, 7 and 8 of the ISO 8 mode cycle.

A family of transmission systems based on a “Planetary Gear - CVT” mechanism is presented here. The systems considered consist of two compound planetary gear trains connected through a CVT pulley system to provide the power/torque split and recirculation function, without the use of additional clutches and/or chain drives. A two degree of freedom system results in which one of the degrees of freedom is directly related to the CVT ratio. The mechanisms considered here combine the gear reduction function of compound planetary gear trains with the continuously variable trans- used as a circulating power control unit. The kinematics and dynamics of this family of systems is presented with emphasis on the belt forces, torques on the various shafts and the overall input/output velocity ratios through the CVT ratio span. Then a parametric analysis is conducted to characterize the effect of the various functional ratios and parameters of the system in terms of the overall performance.

In this paper, a new method for the hydro-dynamic analysis of a sliding cylinder in a fully lubricated parallel track is presented. The method is an extension of Booker's “Mobility Method” (developed for cylindrical journal bearings) to the case of sliding cylinders, in which the clearance between the track and the cylinder, the viscosity of the lubricant, the radius and length of the pin, the sliding velocity and the applied transverse load determine the hydrodynamic behavior of the cylinder. In the Rand Cam™ Engine [1]*, the axicycloidal motion of vanes is driven by a rotor and a cylindrical cam, and one of the alternative designs to provide this function is based on a cylindrical pin sliding within a track which follows the profile of the motion of the main cams of the engine. This function is very important for the engine, since it separates the load bearing function from the sealing function left to the apex-like seals.

Analysis of two types of bearings has been performed for the rotor shaft of the Rand Cam™ engine. Rolling element bearings and a combination of journal and thrust bearings for selected engine configurations have been considered. The engine configurations consist of four, five, six, seven, and eight vanes. The bearing geometry and orientation was also addressed. This analysis is crucial due to the potentially large axial loading on the bearings and the need for the bearing arrangement to be compact and reliable. An emphasis was placed on the combination of fluctuating axial and radial loads and the resulting effect upon the bearings. Tapered roller bearings were found to be effective. However, a combination of journal and thrust bearings is a more compact bearing arrangement for this application. The eight vane configuration is the most desirable configuration based upon the bearing analysis.

The Stiller-Smith mechanism is a new mechanism for the translation of linear motion into rotary motion, and has been considered as an alternative to the conventional slider-crank mechanism in the design of internal combustion engines and piston compressors. Piston motion differs between the two mechanisms, being perfectly sinusoidal for the Stiller-Smith case. Plots of dimensionless volume and volume rate-change are presented for one engine cycle. It is argued that the different motion is important when considering rate-based processes such as heat transfer to a cylinder wall and chemical kinetics during combustion. This paper also addresses the fact that a Stiller-Smith engine will be easier to configure for adiabatic operation, with many attendant benefits.

New high-tech materials which are anticipated to revolutionize the internal combustion engine are being created everyday. However, their actual utilization in existing engines has encountered numerous stumbling blocks. High piston sidewall forces and thermal stresses are some of the problems of primary concern. The Stiller-Smith Engine should provide an environment more conducive to the use of some of these materials. Absent from the Stiller-Smith Engine is a crankshaft, and thus a very different motion is observed. Since all parts in the Stiller-Smith Engine move in either linear or rotary fashion it is simple to balance. Additionally the use of linear connecting rod bearings changes the location of the sidewall forces thus providing an isolated combustion chamber more tolerant to brittle materials and potential adiabatic designs. Presented herein is the development of this new engine environment, from conceptualization to an outline of present and future research.