His research includes design of micro air vehicles, development of innovative design methodologies, and enhancement of engineering education. Jensen has authored approximately 100 papers and has been awarded more $2.5 million of research grants.

No abstract

No abstract

No abstract

A project has been undertaken to design, build and test internal combustion engine poppet valves made from resin transfer molded (RTM) Fiber Reinforced Composites (FRCs). For poppet-valve engines, the valve train mass and stiffness is of particular importance because valve train natural frequency and the onset of valve float and bounce typically limit the engine operating speed. This in turn limits engine power and performance. FRC poppet valves offer the potential for substantial mass reduction as well as increased component stiffness. This enables reduced power consumption by the valve train, and increased overall engine efficiency. Resin transfer molding was chosen because of potential for high-volume production and near-net shape products. Valve design details include; identification of valve operating requirements, fiber orientations, material selection, and evaluation of potential solutions using computerized structural analysis. Mold design includes; mold configuration requirements, fiber placement strategies evaluated, intermediate validation testing done and initial prototype configuration. Results include the final valve design for an exhaust valve, fiber and matrix material selection, fiber placement strategy, and mold configuration. Plans for additional validation testing are presented.

No abstract

No abstract

This paper presents an investigation into the potential efficiency and performance improvements in an internal combustion engine by changing the mass and stiffness of valve train components, specifically the mass of the valve and the stiffness of the valve spring. Changes in valve mass affect the dynamic response of the valve train, so changes in other components must be made to maintain reliable and efficient engine operation. In order to quantify the potential benefits of lightweight engine valves, a dynamic model of the complete valve train system was developed. This model was experimentally validated on a motored engine in which the valve motion was measured for different combinations of valve mass, spring stiffness and engine speed. This paper describes the development and validation of the dynamic model, and discusses the effects of varying the valve mass and valve spring stiffness. It was found that a 75% reduction in the mass of the valves (as expected through the use of fiber reinforced composites) could reduce the maximum camshaft drive torque and frictional power by about 60–70%.