Examinando por Autor "Lozares Abasolo, Jokin"
Mostrando 1 - 8 de 8
Resultados por página
Opciones de ordenación
Ítem AA5754 aluminium alloy springback reduction by post forming electro plastic effect (PFEPE)(Elsevier B.V., 2024-11) Lozares Abasolo, Jokin; Otegi Martinez, Nagore; Trinidad Naranjo, Javier; Barrenetxea Iñarra, Manex; Aizpuru Larrañaga, Iosu; Jimbert Lacha, Pedro José; Mendiguren Olaeta, JosebaPost Forming Electro Plastic Effect (PFEPE) has been proposed as a promising technology for mitigating forming forces and addressing springback challenges in the metal forming industry. However, several research gaps remain unaddressed for the industrialization of this technology. Firstly, there is a lack of experimental validation regarding the impact of stress reduction on springback. Secondly, the potential effect of the skin-effect on the current metrics of stress reduction needs to be evaluated. Additionally, a post-forming electrically assisted elastoplastic material model is necessary for further technology development in stamping processes. This study tackles these challenges by utilizing AA5754H22 as a reference material and integrating a comprehensive experimental campaign with finite element numerical models and empirical material model developments. Our findings confirm that PFEPE facilitates a significant reduction in springback, achieving approximately a 100% reduction. Although the skin-effect introduces non-uniform current flux density distribution, its impact at the macroscopic level is negligible for the studied thin samples. While the numerical results of springback fails to accurately replicate experimental results, the developed material model aligns well with experimental trends.Ítem Characterization of friction coefficient at near solidus forming (NSF) conditions using T-shape compression test(Elsevier Ltd, 2024-08) Sajjad, Muhammad; Agirre Bikuña, Julen; Plata Redondo, Gorka; Lozares Abasolo, Jokin; Mendiguren Olaeta, JosebaAmidst the escalating demand for sustainable manufacturing practices aimed at mitigating global emissions and waste, industries are actively seeking novel forming solutions to address these pressing global challenges. Near Solidus Forming (NSF) processes emerge as a promising alternative to confront such issues, offering the capability to fabricate intricate components reliably while minimizing material waste and energy consumption. This promising manufacturing process is still in its developmental stages for industrial applications, necessitating further exploration and understanding of various factors such as friction, heat transfer, and others. From the literature review, a lack of friction data at these temperatures has been identified. Therefore, this study is dedicated to the advanced characterization of the friction coefficient for Near Solidus Forging (NSF) operations. With that aim, T-shape experimental tests of 42CrMo4 alloy steel have been conducted at high temperatures (up to 1360 °C). Additionally, a lack of consensus on the correct T-shape testing and inverse analysis procedure has been noted. Consequently, apart from the experimental work, an in-depth analysis of the friction coefficient identification procedure has been conducted. As a result, a new geometrical output index is proposed, highly sensitive to the friction coefficient and therefore more reliable compared to state-of-the-art indexes. Furthermore, the influence of the selected geometrical output index and the consideration of sample-to-sample transfer and holding times were studied. Results showed that the increase in workload to consider the sample-to-sample transfer and holding times is not worthwhile, as assuming the average values lead to significantly less work with little impact in the final results (<5 % of error). The study also concludes that a friction coefficient of 0.25, 0.45 and 0.6 has been identified at temperatures of 1250 °C, 1300 °C and 1360 °C, respectively. Additionally, the result of thermal camera showed good agreement with the thermocouple data. Overall, in this study a robust and reliable T-shape testing, and friction coefficient identification procedure is proposed and validated.Ítem Characterization of the heat transfer coefficient at near solidus forming condition using columnar pressing test(Springer Science and Business Media Deutschland GmbH, 2024-11) Sajjad, Muhammad; Agirre Bikuña, Julen; Plata Redondo, Gorka; Lozares Abasolo, Jokin; Mendiguren Olaeta, JosebaThis study addresses the significant gap in the literature regarding the heat transfer coefficient (HTC) under near-solidus forming (NSF) conditions, where materials are shaped close to their solidus state, presenting complex behaviour compared to traditional hot forming processes. Despite the pivotal role of heat transfer in developing a reliable material model for the digital twin (DT), limited data exist particularly regarding HTC characterization at NSF. Additionally, testing methodologies suitable for the high-temperature conditions, crucial for NSF processes, have not been adequately addressed. To fill this gap, this study aims to characterize HTC under NSF conditions using a columnar pressing test. The test was conducted at three different temperatures such as 1250, 1300, and 1360 °C and two different pressures, 2 and 8 MPa. During the test, temperature data was collected at the centre of the sample using a k-type thermocouple. Furthermore, the DT of the pressing test was developed and the three-dimensional finite element model of 42CrMo4 steel was constructed using FORGE NxT® 4.0 FEM software. The simulations were performed with varying HTC values to replicate the experimental test data. Inverse modelling techniques were then applied to compare experimental and simulated data, enabling the characterization and optimization of HTC values under NSF testing conditions. The results demonstrated that HTC in the NSF process is primary impacted by the forming pressure, whereas temperature change showed no variation at the studied ranges. The HTC value of 500 W/m2K and 800 W/m2K was identified at 2 MPa and 8 MPa, respectively. The conclusion of this study aims for a better understanding of heat transfer phenomena in NSF processes, enhancing the reliability of DT for industrial applications.Ítem Digital twin development for the sensitivity analysis of near solidus forming process(Association of American Publishers, 2023-04-19) Sajjad, Muhammad; Plata Redondo, Gorka ; Lozares Abasolo, Jokin; Mendiguren Olaeta, JosebaNear Solidus Forming (NSF) process, performed at semi-solid material state is gaining popularity due to its good physical properties, low manufacturing cost and material waste. Although the process possesses many advantages over traditional hot forging, the nature of the process itself is very complex and due to this the researcher struggles to identify the material behavior at NSF conditions. Especially the material model in this condition has not been stated clearly before and therefore it is important to develop a reliable digital twin (DT) strategy which can validate the material model efficiently. Therefore, the objective of this work is to investigate the influence of all DT parameters like billet material and dimensions, billet and dies temperature, heat transfer coefficient, emissivity, ambient temperature, and friction coefficient, in two industrial components such as H spindle and R spindle. The Taguchi Design of Experiments (DOE) approach combined with numerical simulation in FORGE NxT® is employed to develop the sensitivity analysis of the process. The impact of all parameters in the DT are evaluated in terms of die filling and forming forces, and its importance in the material model is studied. Results show that the newly developed approach proposed a novel optimum NSF-DT calibration strategy for material-model validation. Which can be used to develop an accurate model of the NSF process at the laboratory and industrial scale.Ítem The influence of the adiabatic heating coefficient on the near solidus forming process(Springer-Verlag Italia s.r.l., 2025-03) Sajjad, Muhammad; Agirre Bikuña, Julen; Plata Redondo, Gorka; Lozares Abasolo, Jokin; Mendiguren Olaeta, JosebaThe Near Solidus Forming (NSF) process represents a critical method for shaping metallic components under extreme temperature conditions. When metals deform plastically, significant amounts of heat can be generated, which is due to the conversion of plastic deformation energy in the material often known is adiabatic heating. In this study, the influence of the adiabatic heating coefficient (AHC) on temperature distribution and plastic strain during NSF process is investigated. For this purpose, three industrial benchmarks previously fabricated using NSF techniques are selected to serve as representative cases for analysis. To conduct the analysis, sensitivity studies is performed at two key temperatures: 1360 °C and 1370 °C. These temperatures are chosen to capture the range of operating conditions typically encountered in industrial NSF applications. The simulation tool FORGE NXT® is utilized to investigate the potential effect of AHC on equivalent plastic strain (EPS). The range of potential AHC values considered is between 85% and 100%, as determined from a comprehensive literature survey. The study suggests that the AHC has a minimal effect on the deformation behaviour of 42CrMo4 steel at NSF condition for the studied benchmarks. The findings of this study provide the inside to the importance of AHC in the developing of a reliable Digital Twin (DT) for industrial NSF application.Ítem Sensitivity analysis of near solidus forming (NSF) process with digital twin using Taguchi approach(Shanghai University, 2025) Sajjad, Muhammad; Trinidad Naranjo, Javier; Plata Redondo, Gorka; Lozares Abasolo, Jokin; Mendiguren Olaeta, JosebaForging at near solidus material state takes advantage of the high ductility of the material at the semi solid or soft-solid state while keeping most of the mechanical properties of a forged part. The technology is at maturity level ready for its industrial implementation. However, to implement the process for complex cases the development of an appropriate digital twin (DT) is necessary. While developing a material model, a strong experimental and DT is necessary to be able to evaluate the accuracy of the model. Aimed at having a reliable DT under control, for future material model validations, the main objective of this work is to develop a sensitivity analysis of three NSF industrial cases such as Hook, R spindle and H spindle to develop an adequate DT calibration procedure. Firstly, the benchmark experimentation process parameter noise and experimentation boundary conditions (BCs) parameter uncertainty are identified. Secondly, the three industrial benchmark DTs are constructed, and a Taguchi design of experiments (DoEs) methodology is put in place to develop the sensitivity analysis. Finally, after simulations the results are critically evaluated and the sensitivity of each benchmark to the different inputs (process parameter noise and BC parameter uncertainty) is studied. Lastly, the optimum DT calibration procedure is developed. Overall, the results stated the minimum impact of the material model in terms of dies filling. Nevertheless, even if the material model is the highest impacting factor for the forging forces other inputs, such as heat transfer and friction must be under control first.Ítem Study of forming defects and failure occurrence in the radial-axial rolling of super duplex stainless steel rings(Association of American Publishers, 2023) Murillo Marrodán, Alberto ; García Gil, Eduardo ; Fernández de Gamboa Andrío, Unai; Conde Fernández, Aintzane; Lozares Abasolo, JokinWelding neck flanges are commonly manufactured by radial-axial ring rolling (RARR). The service conditions of these elements are very demanding (mechanical loads and corrosive environments). For this reason, materials such as super duplex stainless steel (SDSS) are used, which could present workability problems under certain process conditions. In this work, a study of forming defects and failure occurrence in the RARR of SDSS flanges has been proposed. Firstly, a finite element model of the industrial RARR process was developed and validated. Then, a multivariate factorial analysis based on a virtual design of experiments was performed to identify the determinant parameters of the process. The diameter of the mandrel was identified as the most determinant parameter. An increase in diameter reduces the probability of developing underfilling defects and the development of cracks in the flange neck. The mandrel radial speed has no significant effect on the cracking of underfill defects while reducing the rotational speed of the king-roll could improve the uniformity of the deformation distribution in the flange section.Ítem Unravelling dynamic recrystallisation in a microalloyed steel during rapid high temperature deformation using synchrotron X-rays(Acta Materialia Inc, 2024-10) Zhang, Kai; Wigger, Tim; Pineda, Rosa; Hunt, Simon A.; Thomas, Ben; Kwok, Thomas; Dye, David; Plata Redondo, Gorka; Lozares Abasolo, Jokin; Hurtado Hurtado, Iñaki; Michalik, Stefan; Preuss, Michael; Lee, Peter D.; Azeem, Mohammed A.Microstructure evolution during high-strain rate and high-temperature thermo-mechanical processing of a 44MnSiV6 microalloyed steel is investigated using in situ synchrotron high-energy powder X-ray diffraction. The conditions selected replicate a newly developed near solidus high-strain rate process designed for reducing raw material use during the hot processing of steels. High temperatures (exceeding 1300 °C) and high strain rate ε˙ = 9 s-1 processing regimes are explored. The lattice strains and dislocation activity estimated from diffraction observations reveal that the microstructure evolution is primarily driven by dynamic recrystallisation. A steady-state stress regime is observed during deformation, which develops due to intermittent and competing work hardening and recovery processes. The texture evolution during the heating, tension, shear deformation and cooling stages is systematically investigated. The direct observation of phase evolution at high-temperature and high-strain rate deformation enables a comprehensive understanding of new manufacturing processes and provides deep insights for the development of constitutive models for face-centred cubic alloys.