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Surface defects were demonstrated to result from high productivity machining (HPM) as well as conventional machining of a titanium alloy Ti-6Al-4V, with HPM causing the larger sized defects. These defects could act as initiation sites for fatigue cracks showing that machining would affect fatigue strength and life of the part produced. A finishing pass appears to remove the defects. Better understanding is needed of the relationships between machining, surfaces, and strength.

High speed machining of aluminum and magnesium helicopter gearcases was experimentally demonstrated to be five times more productive than contemporary conventional commercial practice for suitable operations. Appropriate techniques and performance characteristics are discussed for face milling, endmilling and planetary milling operations. Potential problem areas, such as surface characteristics and machine tool performance requirements are discussed.

The contemporary context of mechanical design engineering undergraduate education is briefly reviewed. A three-course sequence for mechanical design education is proposed which meets the general needs of undergraduate students while providing a strong background for future automotive engineers. A somewhat traditional machine design course with sections on design background, power transmission, and structural design is followed by a course in modern intermediate machine design which covers recent advances in machine design and significant gaps in the traditional design curriculum. A capstone design project course in which the students work in teams completes the sequence. Some suggestions for course content and conduct are presented.

Continuously-variable transmissions are reviewed with an emphasis on heavy agricultural and construction equipment. Designs of split-torque hydromechanical transmissions are discussed. The combination of powershift and hydrostatic elements should provide comfortable, stepless shifting and the ability to allow the vehicle to operate at optimum engine and travel speeds. An integration of a continuously-variable transmission and differential steering is proposed for tracked vehicles.

Issues concerning the use of object-oriented knowledgebases in hydraulic circuit design are discussed. Hydraulic system knowledge representation is described with a semantic association model. Hydraulic circuit design rules are categorized and modeled as integrity constraint or deductive rules. This work demonstrates that an object-oriented knowledgebase could potentially be a viable tool for providing the hydraulic circuit designer with an evaluation of the designed circuit. The techniques need further development to be useful by the practicing designer.

There is an increased interest in spatially-variable field operations, especially fertilizer application. Design concepts for mobile equipment to vary fluid fertilizer rate and mixture are presented and discussed. The potential systems vary the fertilizer component flowrates by changing centrifugal pump speed or by controlling recirculation valves. Although more complex, and hence costly, than conventional machines, spatially-variable fluid fertilizer applicators appear to be feasible utilizing currently-available commercial components.