1,721,085 research outputs found
Additive Manufacturing for Rapid Sand Casting: Mechanical and Microstructural Investigation of Aluminum Alloy Automotive Prototypes
Full text linkThe automotive industry is undergoing a rapid evolution to meet today's challenges; therefore, continuous innovation and product development are needed. Validation tests on prototypes play a crucial role in moving new components into industrial production. There is also a pressing need for faster prototyping processes. In this context, rapid sand casting (RSC), based on additive manufacturing technology, offers a promising solution for a quick production of sand molds. While this technology is already employed in the industry, the need to deepen the general understanding of its impact on the casting properties is still a relevant item. In this study, different geometries of automotive prototypes made of aluminum EN AC 42100-T6 alloy were experimentally analyzed. Microstructural examinations, tensile tests, and fractography and porosity analyses were conducted. The findings demonstrate the considerable potential of RSC, giving, in general, high mechanical properties. A comparative analysis with prototypes produced through traditional sand casting revealed similar results, with RSC exhibiting superior yield strength and stress at brake. However, both technologies revealed a reduced elongation percentage, as expected. Future efforts will focus on standardizing the RSC process to enhance ductility levels
Enhancing Aluminum Alloy Properties Through Low Pressure Forging: A Comprehensive Study on Heat Treatments
No full textThe weight reduction is a key objective in modern engineering, particularly in the automotive industry, to enhance vehicle performance and reduce the carbon footprint. In this context aluminum alloys are widely used in structural automotive applications, often through forging processes that enhance mechanical properties compared to the results for casting. However, the high cost of forging can limit its economic feasibility. Low pressure forging (LPF) combines the benefits of casting and forging, employing controlled pressure to fill the mold cavity and improve metal purity. This study investigates the effectiveness of the LPF process in optimizing the mechanical properties of AlSi7Mg aluminum alloy by evaluating the influence of three different magnesium content levels. The specimens underwent T6 heat treatment (solubilization treatment followed by artificial aging), with varying aging times and temperatures. Microstructural analysis and tensile tests were conducted to determine the optimal conditions for achieving superior mechanical strength, contributing to the design of lightweight, high-performance components for advanced automotive applications. The most promising properties were achieved with a T6 treatment consisting of solubilization at 540 °C for 6 h followed by aging at 180 °C for 4 h, resulting in mechanical properties of σy 280 MPa, σm 317 MPa, and A% 3.5%
Theoretical and experimental procedure for scaling-up RDF gasifiers: The Gibbs Gradient Method
No full textThe thermodynamic Model "Gibbs Free Energy Gradient Method" (GMM), published on the Vol. 90 (2011) of this Journal and validated with literature data, is now applied to the simulation of an experimental campaign realized at the ENEA Research Centre of Trisaia (Italy). The GMM well reproduces the experimental results of steam gasification of refuse-derived fuel (RDF) obtained on two laboratory and pilot scale rotary kilns. Consequently, the experimental syngas composition is put in relation to the main process parameters through a new approach incorporating the GMM for identifying a reliable correlation between the extent of reactions and the gasifier temperature. This correlation appears independent from the scale of the rotary kiln and the residence time in the investigated range of variables. On this basis, the GMM is adapted to become a tool for designing industrial gasifiers starting from experimental data since the required final composition of the syngas and the required performances may be obtained by designing a gasification zone operating at the temperature calculated by the proposed method. It is believed that this procedure is extendable to other geometries and different type of apparatus by studying and including the effect of other parameters. © 2016 Elsevier Ltd. All rights reserved
Effect of fiber orientation and residual stresses on the structural performance of injection molded short-fiber-reinforced components
No full textThe increasingly need of lightweight structures in different sectors is driving new researches about the substitution of metal with polymeric matrix composite. Objective of this work is to optimize the strength design of short-fiber injection molding manifold block, originally made with brass, with the aid of a three-dimensional flow and structural analysis simulations. These Finite Element Analyses (FEA) were based on orthotropic, linear and elastic models including process-induced residual stresses. Through an appropriate interface, the results of injection molding analysis of 35 wt.% fiber reinforced polyphthalamides (PPA) manifold block are transferred to the structural analysis software. Autodesk Moldlfow software was used to predict the fiber orientation and the in-cavity residual stresses considering the flow kinetics and moulding parameters. The Abaqus interface for Moldflow was used to translate this data into a form that can be used for the structural analysis. Finally, this paper reports some experimental tests carried out on the injection moulded component in order to evaluate the internal burst pressure values. The results not only highlighted the importance of carrying out structural simulations, which consider both the orientation of the glass fibre and the residual stresses given by molding, but also showed the usefulness and accuracy of an integrated CAD-FEA approach. The application on a real case demonstrated good agreement with numerical analysis predictions
Reuse of Electric Arc Furnace Slag as Filler for Nitrile Butadiene Rubber
Full text linkThis work shows an innovative application for electric arc furnace (EAF) slag: its use as a filler for nitrile butadiene rubber (NBR). Composites with various EAF slag contents were tested. It was found that the polymer matrix significantly reduces the leaching of slag (determined according to the standard CEN-EN 12457-2) incorporated in the NBR. The processability characteristics determined by the rheometric curves highlight that the EAF slag accelerates the crosslinking kinetics, reducing the production cycle time. Mechanical characterization demonstrated that EAF slag increases hardness and compression modulus. The ability to recover an imposed deformation quantified by the compression set is reduced as the EAF slag amount increases but remains below an acceptable value. It can be stated that in sealing systems, the EAF slag as a filler for NBR positively affects the compound properties. Moreover, NBR filled with EAF slag also has magnetic properties compared with standard rubber
Tribological Behavior of a Selective Laser Melted CoCrMo Alloy under Different Heat Treatment, Loading, and Sliding Conditions
No full textSelective laser melted (SLM) CoCrMo alloy holds promise in various biomedical and industrial applications, requiring exceptional tribological properties to withstand contact interactions and wear. Despite this, research on SLM-CoCrMo tribology remains relatively unexplored. This study presents a comprehensive comparative analysis, evaluating the impact of heat treatments, specifically at 800 °C/2 h, 1150 °C/2 h, and hot isostatic pressing (HIP), under varying load levels (2 N, 5 N, and 7 N) and sliding conditions (single way or reciprocating). The results demonstrate that different combinations of load, sliding condition, and heat treatment induce diverse wear mechanisms, significantly influencing the alloy’s tribological performance. Specifically, the as-built (AB) condition showed the highest wear rates at 2 N, whereas HIP-treated samples exhibited a significant reduction in wear rate compared to AB specimens at 7 N, under both reciprocating and single-way sliding conditions. Among the investigated conditions, HIP treatment emerged as the optimal compromise between wear resistance and mechanical properties. The findings provide valuable insights for optimizing the tribological behavior of the SLM-CoCrMo alloy, especially in load-bearing biomedical applications such as joint implants and prosthetics components
Heat exchanger design and optimization by using genetic algorithm for externally fired micro-turbine
No full textIn this study, a new configuration where syngas produced by downdraft gasifier is feed directly in an externally fired air turbine is discussed. Attention was posed towards the critical component of this configuration: the heat exchanger. To achieve acceptable electrical efficiencies, high temperature of the air at the inlet turbine section was imposed. A code for heat exchanger design was built by using Matlab, while the geometrical optimization was performed by using modeFRONTIER by imposing a multi-objective function to maximize the overall heat transfer coefficient and minimize both costs and pressure drops across the equipment. İ 2018 The Authors. Published by Elsevier Ltd
The effect of partial recrystallization on the corrosion resistance of EN AW6082 forged components evaluated with different tests
No full textStructural automotive components are extensively made of aluminum alloy forgings, due to the elevate strength and low weight required. These products are frequently subjected to recrystallization. Recrystallization, often limited to surface or forging portions, is expected to reduce its tensile strength and corrosion resistance, but the literature is scarce on this subject. For a more comprehensive understanding, the present research studied the corrosion behavior of samples collected from EN AW 6082-T6 forged components, designed to expose both recrystallized and not recrystallized surfaces to the corrosive environment. Several standardized corrosion tests (i.e., PV 1113, ISO 11846, and VW 96380) were applied to assess the most representative with respect to real field exposure. Tensile tests were performed in four different conditions, recrystallized and not recrystallized specimens in an as-forged state or after corrosion. The recrystallization led to a reduction in tensile properties, but this gap was compensated by a higher corrosion resistance than the not recrystallized samples. Consequently, the mechanical properties became comparable after the corrosion test.The main purpose of the paper is to study the effect of recrystallization phenomenon, typically encountered in aluminum alloy forgings, on tensile and corrosion resistance. The results highlight the fact that recrystallization reduced the tensile properties, but the corrosion resistance is higher than that of not recrystallized samples. Consequently, the mechanical properties are comparable after the corrosion test. imag
Wear and Corrosion Characterization of a Ti–6Al–4V Component for Automotive Applications: Forging versus Selective Laser Melting Technologies
No full textSelective laser melting (SLM) is applied to manufacture a Ti–6Al–4V conrod, an engine component, in order to reduce the weight respect to the original version produced by forging with the same alloy. The weight reduction is achieved through a topological optimization and is about 15%. The article focuses on an experimental study of titanium SLM and hot forging components based on evaluation and comparison of properties relevant for automotive applications: metallurgy, corrosion behavior, and wear resistance. The microstructure is duplex, composed of equiaxial α and β grains for both the technologies analyzed; different morphology and distribution of α and β phases are observed as expected. The analysis on corrosion and wear resistance against 100Cr6 highlights very similar properties for the two technologies. Finally, this study confirms that Ti–6Al–4V made by SLM can substitute the traditional forging technologies in the transport field for the properties here studied
Transforming waste into valuable resources: Recycled nitrile-butadiene rubber scraps filled with electric arc furnace slag
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