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More than 200 tensile-shear resistance spot welded specimens were produced and tested to analyze the effect of spot weld spacing, weld size, sheet thickness, and adhesive on the ultimate strength of joints made from a mild hot dip galvannealed steel and an unexposed quality hot dip galvannealed 590 MPa minimum tensile strength dual phase steel (DP590). The geometric layout parameters were analyzed by a design of experiment (DOE) approach. The analysis showed that weld size is a primary factor affecting the strength of the joints for a given material. It was also determined that structural adhesive created a large relative strengthening for joints made from the mild steel. Interactions of the geometrical factors are also presented.

With the stringent emission regulations and renewable energy concerns, hydrogen application either to direct injection combustion or fuel cell application attracts more attention. However, a major obstacle for vehicle utilization of hydrogen as a main fuel is onboard storage. Due to the low mass density, hydrogen has the lowest energy per unit volume among all potential fuels. One of the typical methods to store hydrogen is in very high pressure storage tanks. The high pressure (35 MPa and higher) combined with small size of hydrogen molecules makes the tanks and adjacent fittings prone to leakage, which may cause important potential safety issues, given the wide combustion range and easy ignition of hydrogen. Our research focuses on characterizing the relative importance of basic modes of hydrogen leakage at the joints of commercial stainless steel fittings.

A liquid fuelled, fuel cell auxiliary power unit (APU) can provide efficient, quiet and low pollution power for a variety of applications including commercial and military vehicles. Truck idling regulation, customer comfort or military “stealth” operation by using electrical power, require a device disconnected from the main diesel engine. The power can be utilized for air conditioning as well as other auxiliary systems found on board commercial trucks for driver comfort. In a military vehicle, this regulated power could be supplied to telecommunication and other computer equipment required for military operations. A system designed to be an add-on or retrofit solution using alternative fuel can have the potential to meet these requirements on the hundreds of thousands of existing vehicles currently in service or as optional equipment on a newly procured vehicle.

In the present study, several welded beam and plate specimens are fabricated using an electrical resistance type spot welder and studied experimentally applying the frequency response function approach. The experimental data is used to guide the dynamic finite element modeling effort, and to determine the weld joint representation that most accurately characterizes the measured dynamic response. The results reveal the compliant nature of the spot welds at higher frequencies and in applications consisting of more complex geometrical structures and boundary conditions. This finding shows the inadequacy in the classical rigid element representation that is widely used in current dynamic modeling practices.

A multiaxial spot weld damage parameter and a basic load-life approach are applied to proportional shear and peel loading for a standard SAE variable amplitude loading history. Miner's rule and the rainflow cycle counting method are used to calculate fatigue damage using constant amplitude load-life test data for various ratios of the combined loading. The calculations are compared to test results for an HSLA galv-annealed sheet steel obtained by using the DaimlerChrysler Spot Weld Design Committee multiaxial spot weld test fixture. The applicability of the methods are discussed, as are the crack initiation and propagation behavior of the specimens.

Prototype selective catalytic reduction (SCR) systems using urea have been demonstrated on diesel trucks in Europe in recent years. In view of upcoming stringent emissions control standards for US HD diesel engines, urea-SCR is being evaluated by US engine and truck manufacturers. The authors and their companies have worked jointly on a project to develop, test, and demonstrate urea-SCR on a US HD diesel engine and Class-8 truck. A prototype urea-SCR system was applied to a 12-liter HD diesel engine. The engine model selected is rated at 350 bhp and is common for highway trucks. The only engine modifications were changes to the injection timing control map in order to better suit the application of the urea-SCR system. This paper details two demonstration phases of the project as follows. The first phase includes recent emissions cell tests using a new compact SCR catalyst and an engine calibration optimized for lower NOX.

This paper describes the procedures used to reduce the tonal noise of a class eight truck engine timing gear train that was initially found to be objectionable under idle operating conditions. Initial measurements showed that the objectionable sounds were related to the fundamental gear mesh frequency, and its second and third harmonics. Experimental and computational procedures used to study and trouble-shoot the problem include vibration and sound measurements, transmission error analysis of the gears under light load condition, and a dynamic analysis of the drive system. Detail applications of these techniques are described in this paper.

Mack Trucks' E7 direct injection heavy-duty diesel engine is a four cycle, in-line six cylinder design. The 728 cu in. (12 1) engine is turbocharged and chassis mounted air-to-air aftercooled. The E7 is being introduced in 1989 with power ratings of 250 hp to 400 hp (186 kW to 298 kW) at 1700 to 1800 rpm, calibrated to 1990 EPA standards. Highlights of the E7 engine's design, development and performance are presented. Information is included which illustrates the strategies utilized to attain program goals of controlling weight and cost while extending power ratings, reducing emissions levels, and improving fuel economy, serviceability, durability and reliability.

Two ceramic monolith wall flow diesel particulate traps, incorporating a new split flow design with a base metal catalytic coating were tested on line haul highway trucks to investigate their performance characteristics. The trucks were equipped with a 300 HP turbocharged and after-cooled engine. After-cooler by-pass was used to effect the regeneration of the trap and an elapsed-time scheme was employed to control the regeneration process. Tests were terminated after one trap completed 147,500 miles of operation on the truck for in-depth examination of the trap to determine the cause of substantial increase in back pressure. Tests with the second trap of identical design was also terminated due to filtering efficiency loss, the cause of which was traced to a flaw in the canning arrangement. This arrangement permitted exhaust flow to by-pass the element and led to melt down of the trap, due to reduced flow during regeneration.

A foundation of highway truck ride and cab suspension historical evolution is laid describing the influence of marketplace demands, highway conditions, and government laws. Ride quality test methods are revealed along with variables tried and conclusions drawn. These data and techniques are then used to design cab suspension systems for a new line of truck products including both conventional and COE cabs.

This paper describes development of a full-scale laboratory truck axle test used to predict the field performance of gear lubricants in heavy truck use. The relationship between laboratory results and known field performance will be described, as will a unique way of analyzing laboratory results. Data will also be presented which will show the laboratory test to be both repeatable and reproducible. Finally, data will be presented which shows lubricant additive type to play a vital role in defining field performance.

A new 998 CID V8 engine series has been developed by Mack Trucks, Inc. to supplement its line of heavy duty diesel engines. These engines, the E9 Series, are available in two configurations--a 400 bhp (298 kW) high torque rise version and a 440 bhp (328 kW) conventional torque backup version. Increased horsepower and improved fuel economy were achieved through the development of a chassis mounted charge air cooler and a new four-valve cylinder head. In addition, significant durability improvements were obtained due to the reduced thermal loadings resulting from the lower charge air temperatures. Additional noteworthy features include a new injection pump, improved lube oil system, advanced piston design, and proper selection of seals and gasket materials.

The application of an advanced state-of-the-art air inlet system has produced a high specific output, high torque rise, heavy-duty diesel truck engine. By integrating a compact plate-fin air-to-air heat exchanger with the cooling air driven by a novel tip turbine fan, a 25% increase in power output has been achieved with minimal increase in mechanical engine loads. The use of an aluminum two-piece piston which prevents side thrust loading on the ring-carrying head section results in improved ring life and reduced oil consumption.

The truck flywheel power takeoff has proven itself as a reliable means of supplying continuous power to a variety of mounted equipment. The features of available units are described in detail in an effort to provide the design and application engineer with complete information regarding their function and application, and to stimulate expanded usage of this constant power source.