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Date of Award


Document Type

Campus Access Master's Report

Degree Name

Master of Science in Mechanical Engineering (MS)

Administrative Home Department

Department of Mechanical Engineering-Engineering Mechanics

Advisor 1

Gregory Odegard

Committee Member 1

Trisha Sain

Committee Member 2

Paul Van Susante


Different molding sands generates different surface finish on casting irons. The effect of skin roughness on failure mechanism and on fatigue properties is presented in this report. Fracture surface analysis for as-cast chemically bonded, green sand, inorganically bonded sand samples, as well as machined chemically bonded samples are discussed. Fractography provided significant information regarding mode of failure, crack initiation sites and crack propagation path. Quantification of surface profile was done by performing surface profilometer tests. Profilometer tests gave a detailed picture and accurate areal parameters for surface flaws present on all the samples. Based on fractography observations and areal parameters, stress intensity factor (SIF) at surface were calculated by using the appropriate stress intensity solution formulated by J.C. Newman and I.S. Raju [4] [5] [6]. Aspect ratio evolution with respect to relative crack depth was estimated from macroscopic fractography. Using Paris Law relation, an analytical model was created to predict percentage change in fatigue life of as-cast samples with respect to machined samples. Fractography results showed that cracks initiated at the surface and propagated in semi-elliptical and quarter-elliptical fashion. Analytical SIF and Paris Law results estimates that all as-cast samples will fail earlier than machined samples with green sand displaying poorest properties.