Saudi Cultural Missions Theses & Dissertations
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Item Restricted Dynamic Response of 3D-Printing Heterogeneous Beam(Cranfield University, 2023-08) Alhamdan, Naif; Khan, MuhammadHeterogeneous structures differ in composition, characteristics, and spatial distribution. These structures have non-uniform composition, features, or spatial distribution. High-temperature structural components and thermal barrier materials have been investigated for FGMs in aerospace engineering. Their design has also been utilised in high-speed aeronautical vehicles. This work predicts the dynamic response of inhomogeneous beams by studying structural factors' mechanical behaviour. Structures with inhomogeneity, such as fractures and segment locations, must behave reliably non many engineering applications. The study methodically examines how inhomogeneity, crack depth, and segment position affect fundamental frequency and resonance amplitude. The results indicate if that specific segment with lower infill density is far away from the beam's fixed end, the natural frequency results are higher. An empirical model with 0.96 R-square value was developed to estimate the fundamental frequency for the beam with local inhomogeneity and was validated.11 0Item Restricted VERTICAL AND ROCKING VIBRATIONS OF MACHINE FOUNDATIONS EMBEDDED IN GRS SAND(University of Colorado, 2024-04-19) Binmahfouz, Yahya; Chang, Nien-YinMachine foundations and neighboring structures can be adversely affected by excessive machine vibration. To minimize vibration amplitude and to meet Richart's Chart (1965) performance requirements, the machine operating frequency must differ sufficiently from the system’s natural frequency. This dissertation studies the influence of different spacing of woven geotextile (Amoco 4800) and foundation-embedded depth on machine foundation behavior under vertical and rocking vibrations, respectively. Large-scale experiments are conducted to simulate machine foundation behavior using a rigid steel soil container (RSSC) measuring 48 inches long by 48 inches wide and 48 inches high. A 12-inch circular steel model foundation of 3 inches thick is used in this study. The foundation is placed at 12, 6, and 0 inches from the top of the first woven geotextile layer. This is done in Ottawa sand prepared to a relative density of 70 percent. Several reinforcing patterns were used to investigate how the reinforcing effect changes with increasing reinforcing layers. The reinforcing spacings are 12, 8, and 4 inches. Material testing system (MTS machine) provides harmonic loads for vertical and rocking vibrations. After the finite element analysis was verified to be effective, parametric studies of the machine foundations were performed. Then, multivariate regression analyses were conducted. These findings reveal that reducing the spacing of woven geotextile layers while increasing embedment depths results in decreased displacement amplitude and increased natural frequencies. Such adjustments enhance the foundation's capacity to withstand dynamic loads.37 0