Ciencias Exactas y Ciencias de la Salud
Permanent URI for this collectionhttps://hdl.handle.net/11285/551039
Pertenecen a esta colección Tesis y Trabajos de grado de las Maestrías correspondientes a las Escuelas de Ingeniería y Ciencias así como a Medicina y Ciencias de la Salud.
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- Mathematical modeling of ultrasonic micro injection molding using dimensional analysis for manufacturing polymeric parts(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2020-11-23) Salazar Meza, Marco; Elías Zúñiga, Alex; hermlugo/tolmquevedo; Olvera Trejo, Daniel; Escuela de Ingeniería y Ciencias; Campus Monterrey; Martínez Romero, OscarUltrasonic micro injection molding is a novel processing method to produce micro-scaled specimens at low production volumes that overcomes the material degradation originated by high residence times, and reduces material waste compared to conventional injection molding. Ultrasonic micro injection molding deals with ultrasonic energy and polymers under cyclic loads which experience a phase-change from solid to a non-Newtonian fluid flowing to fill a mold. Attempts have been made to study each of the steps of the process, all of them needing powerful FEM software and the establishment of several assumptions to simplify the calculus on the otherwise thermomechanical coupled problem with different time scales. This research work presents a methodology to reduce the mathematical complexity of the process while preserving the physics of the system through the usage of dimensional analysis. A correct relationship of processing parameters and energy consumption values was obtained using four different polypropylenes with distinct mechanical properties, all of them fitting adequately in the proposed formulation composed of dimensionless groups obtained through the Buckingham-Pi Theorem. A mathematical expression capable of quantitatively predict energy consumption from processing parameters was obtained. Additionally, a relationship between the processing parameters and the Young’s Modulus of the produced specimens was found, and a mathematical expression to calculate this property using processing parameters was stablished.
- Dimensional analysis for tuning Selective Laser Melting parameters for near-full density of Inconel 718(Instituto Tecnológico y de Estudios Superiores de Monterrey, 2020-06) Estrada Díaz, Jorge Alfredo; ELIAS ZUÑIGA, ALEX; 19150; Elías Zúñiga, Alex; ilquio, emipsanchez; Martínez Romero, Oscar; Olvera Trejo, Daniel; School of Engineering and Sciences; Campus Monterrey; Rodríguez Salinas, Juan JoséSelective laser melting is a powder bed fusion process that allows the production of metallic pieces of high geometrical complexity. Full densification is regarded as fundamental to achieve mechanical integrity. Nevertheless, doing so for a new material requires an intensive, in time and resources, experimentation stage in order to set proper manufacturing parameters. In this work, dimensional analysis is used to develop a general mathematical model on bulk density of SLMed components taking volumetric energy density, scanning speed and powder’s thermal conductivity, specific heat capacity and average grain diameter as independent variables. Strong relation between dependent and independent dimensionless products was observed. Bulk density is found to be proportional to volumetric energy density and be affected by scanning speed by a factor of negative two. Inconel 718 probes were produced and a particular expression, in the form of a first order polynomial, for its bulk density,in the independent dimensionless product π1 range from 3.17x10−8 to 4.6 x10−8 was obtained. In this range, better densification is achieved at lower scanning speed and lower laser power. The first is related to higher exposure time and ensuring full melt of the powder, and the second may be due to powder particle sublimation / ejection due to improperly large laser power conditions. An average relative density of 95.218% was measured. An average error percentage of 1.6503% between experimental and predicted bulk density (and dimensionless density) was achieved. A mathematical tool for tuning scanning speed to achieve full densification, with respect to laser power, was developed. Moreover, particular conditions for achieving so for Inconel 718 in the π1 range was provided.