A new method for predicting forced vibratory blade response to total pressure distortion has been developed using modal and harmonic analysis. Total pressure distortions occur in gas turbine engines when the incoming airflow is partially blocked or disturbed. Distorted inlet conditions can have varying effects on engine performance and engine life. Short-term effects are often in the form of performance degradation where the distorted airflow causes a loss in pressure rise, and a reduction in mass flow and stall margin. Long-term effects are a result of vibratory blade response that can ultimately lead to high cycle fatigue (HCF), which in turn can quickly cause partial damage to a single blade or complete destruction of an entire compressor blade row, leading to catastrophic failure of the gas turbine engine. A better understanding and prediction of vibratory blade response is critical to extending engine life and reducing HCF-induced engine failures. This work covers the use of finite element modeling coupled with computational fluid dynamics-generated pressure fields to create a generalized forcing function. The first three modes of a low-aspect-ratio, transonic, first stage blade of a two-stage fan were examined. The generalized forcing function was decomposed to the frequency domain to identify the dominant harmonic magnitude present, as well as other contributing harmonics. An attempt to define the relationship between modal force with varying total pressure distortion levels produced a sensitivity factor that describes the relationship in the form of a simple multiplier. A generalized force was applied to the blade and varied harmonically across a frequency range known to contain the first natural frequency. The mean rotor stress variation was recorded and compared to experimental results to validate the accuracy of the model and verify its ability to predict vibratory blade response accurately. / Master of Science

This research studies the effects of a damage arrestment device embedded between a carbon fiber facesheet and foam core to find whether there is an increase in the structural integrity of the sandwich composites. Experimental and theoretical finite element analyses are implemented for two different composite sandwich geometries; plates and beams. Each structure consisted of the same loading criteria and was restricted to the same vibration fixture during the experiment. An accelerometer was placed on the composite plate to record the amplitude and the natural frequencies of the composite structure. Each composite specimen is then fixed to the surface of the Cal Poly Shake Table by two aluminum block fixtures. The mechanical properties of LTM45/CF1803 pre-impregnated carbon fiber and Last-A-foam FR 6710 polyvinylchloride foam were experimentally analyzed using ASTM D3039 and ASTM D1621 standards respectively to determine the material’s mechanical properties. By using the finite element program COSMOS with the pre-software GeoStar, accuracy representation were created to compare numerical, analytical, and theoretical results.

Actualmente la población limeña no cuenta con viviendas propias y seguras; por ello, surge el auge del rubro de la construcción masiva con grandes edificaciones multifamiliares, cuya resistencia al impacto telúrico de enorme magnitud de 8 a 9 grados sigue en prueba sísmica; por ende, es muy relevante realizar la comparación del análisis del método modal espectral de la estructura (desplazamientos y aceleraciones respecto al suelo) y un análisis del método tiempo-historia donde se obtendrán las deformaciones máximas de la estructura de los edificios en este presente estudio; asimismo, evaluará la vulnerabilidad de la construcción estructural mediante acelerogramas sintéticos utilizando como espectro objetivo el espectro de peligro uniforme obtenido en el Parque de la Reserva, Cercado de Lima, por medio de un estudio peligro sísmico para un periodo de retorno de 475 años, reconociendo el comportamiento estructural ante un sismo de gran magnitud. El presente estudio titulado: Análisis de la amplificación sísmica de edificios del Cercado de Lima – Lima y La Punta – Callao por medio del análisis modal espectral y tiempo – historia mediante acelerogramas sintéticos; cuyo objetivo es realizar la comparación de dichos métodos en 4 edificios (2 de 5 niveles y 2 de 12 niveles) cuya configuración estructural es de muros de concreto armado, los cuales se estudiaran en dos distintos tipos de suelo (Cercado de Lima y La Punta) con la finalidad de obtener resultados de derivas, fuerzas, desplazamientos y aceleraciones para determinar la amplificación sísmica en los suelos mencionados, y así optar por el método de análisis más óptimo. Asimismo, el propósito del presente estudio es conocer el comportamiento de la edificación acorde con la realidad peruana; es decir edificaciones con periodos cortos; el cual evaluará la vulnerabilidad mediante acelerogramas sintéticos, reconociendo el comportamiento estructural ante una eventualidad sísmica de gran magnitud. / Currently, the population of Lima does not have their own and secure homes; For this reason, the boom in the field of massive construction emerges with large multi-family buildings, whose resistance to the telluric impact of enormous magnitude of 8 to 9 degrees continues in seismic testing; therefore, it is very relevant to make the comparison of the analysis of the spectral modal method of the structure (displacements and accelerations with respect to the ground) and an analysis of the time-history method where the maximum deformations of the structure of the buildings will be obtained in this present study. ; Likewise, it will assess the vulnerability of structural construction using synthetic accelerograms using the uniform hazard spectrum obtained in Parque de la Reserva, Cercado de Lima as the objective spectrum, through a seismic hazard study for a return period of 475 years, recognizing structural behavior in the face of a large earthquake. The present study entitled: Analysis of the seismic amplification of buildings in Cercado de Lima - Lima and La Punta - Callao by means of spectral modal analysis and time - history using synthetic accelerograms; the objective of which is to compare these methods in 4 buildings (2 of 5 levels and 2 of 12 levels) whose structural configuration is made of reinforced concrete walls, which will be studied in two different types of soil (Cercado de Lima and La Punta ) in order to obtain results of drifts, forces, displacements and accelerations to determine the seismic amplification in the mentioned soils, and thus opt for the most optimal analysis method. Likewise, the purpose of this study is to know the behavior of the building in accordance with the Peruvian reality; that is to say buildings with short periods; which will assess vulnerability using synthetic accelerograms, recognizing the structural behavior in the event of a large seismic event. / Tesis