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Book Part Citation - WoS: 6Citation - Scopus: 10Stereolithography and its applications(de Gruyter Oldenbourg, 2020) Oliaei, Samad Nadimi Bavil; Nasseri, BehzadAdditive manufacturing (AM) using cost-effective, accurate, and fast processes is one of the major challenges of today's manufacturing community. Stereolithography (SL or SLA) is a promising technique of AM that is believed to satisfy these requirements. In this process, photopolymerization is used to obtain a 3D model of the desired parts directly from their computer-aided design models. The process works by focusing an ultraviolet (UV) laser on a reservoir of photosensitive polymer resin to solidify it layer by layer, resulting in the desired 3D shape. In this chapter, photopolymerization process and how photopolymers response when they are exposed to UV light sources are discussed along with the application of SLA process in different industries such as manufacturing of industrial parts, including military, medical, and biomedical applications. The physicomechanical properties of fabricated polymeric parts will be explained, including viscosity, tensile strength, elastic modulus, flexibility, and toughness. Some case studies regarding the application of this method for polymeric composite material fabrication, preoperation phantom models, scaffolds preparation used in tissue engineering, and drug-loaded models are discussed.Article Citation - WoS: 12Citation - Scopus: 11Effect of Constitutive Material Model on the Finite Element Simulation of Shear Localization Onset(Elsevier, 2020) Yilmaz, Okan Deniz; Oliaei, Samad Nadimi BavilOne of the most challenging problems in the field of machining is to determine the onset of shear localization. The consequences of the emergence of shear localized chips are fluctuations in the machining forces, tool wear, deterioration of the surface quality and out-of-tolerance machined components. Several constitutive material models are developed for the simulation of shear localization during machining, especially for Ti6Al4V. However, the accuracy and capability of the proposed models for the prediction of shear localization onset have not been investigated yet. In this study, the effect of different constitutive material models in the prediction of shear localization onset has been investigated. Different material models are studied including the Johnson-Cook (J-C) material model with Cockcroft-Latham damage model, J-C material model with a J-C damage model, models based on modified J-C material models (MJ-C) with strain softening terms, and material model with power-law type strain hardening and strain rate sensitivity, with polynomial thermal softening and polynomial temperature-dependent damage. The results of the finite element models are verified using orthogonal cutting experiments in terms of chip morphology and machining forces. Metallography techniques are used along with SEM observations to elucidate the distinction between continuous and shear localized chips. The results of this study indicate that three models are capable of predicting shear localization onset. However, when compared to the experiments, where a critical cutting speed of 2.8 m/min is obtained for shear localization onset, the results revealed that the model proposed by Sima and Ozel (2016) which is a model based on MJ-C model with temperature-dependent overarching modifier and temperature-dependent material model parameters is more accurate for the prediction of shear localization onset during machining Ti6Al4V. This model is shown to reveal a good prediction for the machining forces as well.Article Citation - WoS: 19Citation - Scopus: 21Plateau Honing of a Diesel Engine Cylinder With Special Topography and Reasonable Machining Time(Elsevier Sci Ltd, 2020) Sadizade, Babak; Araee, Alireza; Oliaei, Samad Nadimi Bavil; Farshi, Vahid RezaeizadDeep valleys and flattened peaks are essential characteristics of the finished cylinder bore surface, which is known as the plateau surface. Generally, a honing process is done in three steps to achieve a plateau surface, which is costly and time-consuming and acts as a bottleneck for cylinder block machining line. The real challenge is to select optimum levels of honing process parameters to achieve desired surface characteristics with minimum machining time. The aim of this study is to examine the influence of the input parameters of the honing process on the surface texture of diesel engine cylinder bore. The Rk family parameters are used for surface roughness evaluation and the honing crosshatch angle, in accordance with engine design requirements, which was fixed for all experiments. Optimization by means of the desirability function technique allowed determining most appropriate conditions to desirable roughness (surface quality) and/or minimize machining time (productivity). Based on the findings of this study the conventional three-stage honing process has been replaced by the two-stage process. Using the proposed two-stage honing process the intended plateau surface in cylinder bores are achieved and a remarkable reduction in the honing process time is obtained. Consequently, the process efficiency is improved significantly.Article Citation - WoS: 22Citation - Scopus: 27Modeling and Analysis of Surface Roughness of Microchannels Produced by Μ-Wedm Using an Ann and Taguchi Method(Korean Soc Mechanical Engineers, 2017) Jafari, Rahim; Kahya, Muge; Oliaei, Samad Nadimi Bavil; Unver, Hakki Ozgur; Ozyurt, Tuba OkutucuMicrochannel heat exchangers are used to remove the high heat fluxes generated in compact electronic devices. The roughness of the microchannels has a significant effect on the heat transfer characteristics, especially the nucleate boiling and pumping power. Therefore, development of predictive models of surface texture is of significant importance in controlling heat transfer characteristics of these devices. In this study, micro-Wire electrical discharge machining (mu-WEDM) was employed to fabricate metal-based microchannel heat sinks with different surface textures. First, experiments were conducted to achieve the desired surface roughness values. Oxygen-free copper is a common material in the cooling systems of electronic devices because of its high thermal conductivity and low cost. Design of experiment approach based on the Taguchi technique was used to find the optimum set of process parameters. An analysis of variance is also performed to determine the significance of process parameters on the surface texture. An artificial neural network model is utilized to assess the variation of the surface roughness with process parameters. The predictions are in very good agreement with results yielding a coefficient of determination of 99.5 %. The results enable to determine mu-WEDM parameters which can result in the desired surface roughness, to have a well-controlled flow and heat transfer characteristics for the microchannels.Conference Object Citation - WoS: 1On the Digital Manufacturing Development Applying Engineering Informatics as a Discipline of Field Study(Ieee, 2018) Dadvandipour, Samad; Oliaei, Samad Nadimi BavilThe digital manufacturing system is the process of product lifecycle management which considers the development of a perfect product. It provides the processing of manufacturing system, to be improved and optimized by the engineerings. Digital manufacturing has always been a promising technology to reduce production lead time, the cost minimization and responding to the marketing on time as well as producing qualified and quantified products over the last decades. This paper is a study review of digital manufacturing system model using holonic concept. The paper presents the characteristic of existing entities integrated with knowledge-based systems along with information science and technology. Furthermore, the paper shows an ongoing theoretical supplementary approach using computer-aided production and control (CAPC) system with three components, corresponding to the manufacturing of the products with the least time, optimum cost, and qualified product.
