Available at: https://digitalcommons.calpoly.edu/theses/1996
Date of Award
MS in Mechanical Engineering
Composite materials hold great potential for the replacement of traditional materials in machines utilized on a daily basis. One such example is within an engine block assembly where massive components inherently reduce the efficiency of the system they constitute. By replacing metal elements such as connecting rods, cylinder caps, or a crank shaft with composite alternatives, a significant increase in performance may be achieved with respect to mechanical strength, thermal stability, and durability, while also reducing mass. Exploration of this technology applied to a connecting rod geometry was investigated through a combination of process development, manufacturing, numerical analysis and testing. Process development explored composite material options based on experimental characterization, fabrication, and machining methods. Finite element analysis provided insight into model and data accuracy, as well as a basis for study on a unidirectional composite I-beam geometry. Destructive testing of the composite connecting rods provided data for a strength to weight ratio comparison with the original steel component. The composite connecting rods exhibited weight savings of 15%-17% that of the steel component. The rod made of woven composite material exhibited an elastic modulus of 68.1 Msi in its linear behavior before failure, thereby exhibiting a higher stiffness than the steel rod tested. Although the failure strengths were 25% below the required design load, the calculated strength to weight ratios showed favor for the composite alternatives.