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A new fatigue test specimen configuration has been developed which allows testing of spot welded joints in a fully reversed axial fatigue mode in a life range from 5 × l03 to 1 × 107 cycles. The specimen, a unique square concentric tube arrangement, tests four spot welds simultaneously. The materials tested in this program included three dual-phase steels, an SAE 940X grade, SAE 1020 steel and a cold rolled, low carbon steel - SAE 1006AK for purposes of comparison. The general results indicate the superiority of the dual-phase steels in the low life region with all steels showing equivalent behavior beyond 5 × 105 cycles. Additionally, beneficial effects of increased steel thickness and increased nugget diameter were observed.

Experimental fuels made up of cottonseed oil, transesterified cottonseed oil (methyl ester) and No. 2 diesel fuel have been compared to a baseline No. 2 diesel fuel in a turbo-charged, open chamber diesel engine. All fuel blends were analyzed and their properties compared to those of typical No. 2 diesel fuels. Test results include data on performance, gaseous emissions and limited (200-hour) cyclic durability. Crankcase oil samples were withdrawn at regular intervals during durability tests and analyzed for indications of fuel-lubricant compatibility. The paper presents the data obtained and discusses effects of fuel properties and engine operating conditions on the short and long-term response of existing diesels.