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The accurate prediction of burst of hydroformed tubes is a research area of considerable importance in order to evaluate a design before prototyping. This report applies the presently available criteria (forming limit diagram, stress-based forming limit diagram, extended stress based forming limit curve and the plastic strain criterion) to some of the benchmark examples carried out by the Auto/Steel partnership. It was found that the formability predictions are lowest if the plastic strain criterion is used and highest if either the stress-based criteria are used. Predicted and measured results were also compared.

Federal standards that mandate improved fuel economy have resulted in the increased use of lightweight materials in automotive applications. However, the environmental burdens associated with a product extend well beyond the use phase. Life cycle assessment is the science of determining the environmental burdens associated with the entire life cycle of a given product from cradle-to-grave. This report documents the environmental burdens associated with every phase of the life cycle of two fuel tanks utilized in full-sized 1996 GM vans. These vans are manufactured in two configurations, one which utilizes a steel fuel tank, and the other a multi-layered plastic fuel tank consisting primarily of high density polyethylene (HDPE). This study was a collaborative effort between GM and the University of Michigan's National Pollution Prevention Center, which received funding from EPA's National Risk Management Research Laboratory.

This paper describes a bench method to evaluate the frictional behavior, under scuffing conditions, of some test coupons of standard materials currently used in making cylinder bores and pistons. The usefulness of this method is in evaluating new materials and coatings that may enable the elimination of iron liners from engine blocks. While investigating the potential application of Plasma Source Ion Implantation (PSII) on engine piston/bore materials, we have systematically studied the scuffing related friction behavior of aluminum 390 alloy and cast iron. A pin-on-disk tribometer is used under dry sliding conditions. Testing parameters for simulating cold scuff in bench tests have been specified. This proposed test method offers a screening tool desirable for the development of PSII technology and may also be useful for the design of other new surface modification techniques.

This paper examines the potential use of diamond-like carbon (DLC) on aluminum alloy pistons of internal combustion engines. Our approach is to apply a DLC coating on the piston running against an aluminum-390 bore thus eliminating the iron liners in a standard piston/bore system. Experimental data, using a pin-on-disk tribometer under unlubricated test conditions, indicate that the performance of the DLC coating against aluminum 390 exhibits superior friction resistance compared to aluminum-390 against cast iron; the latter material couple representing the materials currently being used in production for the piston/bore application. Moreover, by thermally cycling the DLC coatings we show that improved friction and wear properties can he maintained to temperatures as high as 400°C.

ACuZinc™ 5, a GM-patented, high-performance ternary zinc-copper-aluminum alloy which is suitable for manufacturing net shape die castings, plays a vital role in the success of new automotive parts and systems. The new parts were designed to meet the auto industry's higher load and safety specifications. The superior mechanical properties of ACuZinc™ make it suitable for structural applications where commercial zinc die casting alloys have been found to be inadequate. From a business viewpoint, ACuZinc™ can help in penetrating new markets by competing for cast iron, powder metal and brass applications. ACuZinc is a registered GM trademark.