Browsing by Subject "Dynamics of machinery"
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Item Effects of computer animated instruction upon cognition of undergraduates in an agricultural power technology course(Texas Tech University, 2002-12) McGregor, Kyle W.The utilization of visual elaboration has been a key component of the educational process for instmctors of agricultural power technology. Traditionally, still illustration and representatives of real equipment (realia) have been utilized to teach the hidden theoretical concepts that comprise the most basic operational processes of the internal combustion engine and its accompanying systems. Exponential technology advancement has allowed the development of a new mode of visual elaboration in the form of highquality computer generated animation. This dissertation, which utilized the dual coding theory as a theoretical framework, is the first of its kind to compare the use of traditional visual elaboration in agricultural power technology with that of the traditional methods and the added component of computer-generated animation. Computer-generated animations are most effective when used with topics that are abstract, vague, hidden or too fast or slow to view. When applied to operational theory of common internal combustion engines, animation is a natural fit. Animation must also be utilized with suitable content and an appropriate learner in order to be effective. Animations are beneficial when compared to still illustration and realia because they offer the benefit of motion and trajectory. The study sought to identify any significant benefits that would result from the addition of animation to an agricultural power technology lesson.Item Prediction of the dimensional instability resulting from machining of residually stressed components(Texas Tech University, 1995-08) Shin, Shang HyonResidual stresses, built into most manufactured components, are revealed most dramatically during subsequent machining operations. Depending on the magnitude and distribution of the original residual stress state, the remaining part of a machined component distorts in order lo maintain the equilibrium of internal forces, resultng in a new state of residual stress distribution in the remaining material. Given a known residual stress state in a material, the purpose of this research was to develop a methodology for the prediction of machining-induced distortions and the determination of the new state of residual stresses in the remaining material. In the first phase of this work, closed-form equations for the distortions of a residually stressed block, subjected to surface layer removal, were developed. Experimental and finite element simulations of the surface layer removal were also conducted and compared to the closed-form solutions. In the second phase of this study, analytical solutions for the distortions and residual stress re-distribution in a cylinder subjected to machining of the inner surface were developed. The original residual stress state was determined by the elasto-plastic solution of a cylinder subjected to the autofrettage process as well as the finite element simulations of the autofrettage process. The effect of isotropic as well as cylindrically orthotropic material properties on the ensuing machining distortions and the redistributions of residual stress state were studied. Closed-form solutions and finite element results of this study demonstrated excellent agreement in the determination of distortions and the new state of residual stresses due to material removal operations.