Grain size and formation of the Peripheral Coarse Grain(PCG)defect influence the mechanical and crash properties of extruded profiles.Controlling microstructural evolution during the extrusion of 6XXX series aluminum ...Grain size and formation of the Peripheral Coarse Grain(PCG)defect influence the mechanical and crash properties of extruded profiles.Controlling microstructural evolution during the extrusion of 6XXX series aluminum alloys is therefore essential to ensure the performance of structural components.In this work,three profiles with the same nominal geometry were extruded with a die comprising three different bearing geometries to create different extrusion conditions.Each profile was analyzed experimentally to gather data on the microstructure and mechanical properties.Bulge testing revealed that Profile 2,with the thickest PCG layer(490-1150µm),exhibited worse mechanical performance,with a hoop strain at fracture of 0.08 and a peak load of 51.5 kN,compared to Profiles 1 and 3,which had higher hoop strains(0.13 and 0.14)and peak loads(56.1 and 57.6 kN,respectively).Finite Element Method(FEM)simulations of the extrusion process were carried out using Qform Extrusion UK with a post-processing subroutine developed and implemented to calculate additional parameters such as the stored energy,percentage dynamic recrystallization,grain size,and PCG formation based on standard output parameters from the simulation including strain,temperature and strain rate.The simulation demonstrated that the highest strain rate(40-220 s^(-1))and stored energy(150,000-440,000 J m^(-3))in Profile 2 led to the thickest PCG layer.Based on these results,the proposed predictive model was validated against experimental data,demonstrating high accuracy in predicting PCG thickness and grain size while effectively capturing the influence of process parameters on microstructural evolution.展开更多
An innovative approach was introduced for the development of a AA6063 recrystallization model.This method incorporated a regression-based technique for the determination of material constants and introduced novel equa...An innovative approach was introduced for the development of a AA6063 recrystallization model.This method incorporated a regression-based technique for the determination of material constants and introduced novel equations for assessing the grain size evolution.Calibration and validation of this methodology involved a combination of experimentally acquired microstructural data from the extrusion of three different AA6063 profiles and results from the simulation using the Qform Extrusion UK finite element code.The outcomes proved the agreement between experimental findings and numerical prediction of the microstructural evolution.The trend of the grain size variation based on different process parameters was accurately simulated,both after dynamic and static recrystallization,with an error of less than 25% in almost the whole sampling computations.展开更多
In the field of bone tissue engineering,particular interest is devoted to the development of 3D cultures to study bone cell proliferation under conditions similar to in vivo ones,e.g.by artificially producing mechanic...In the field of bone tissue engineering,particular interest is devoted to the development of 3D cultures to study bone cell proliferation under conditions similar to in vivo ones,e.g.by artificially producing mechanical stresses promoting a biological response(mechanotransduction).Of particular relevance in this context are the effects generated by the flow shear stress,which governs the nutrients delivery rate to the growing cells and which can be controlled in perfusion reactors.However,the introduction of 3D scaffolds complicates the direct measurement of the generated shear stress on the adhered cells inside the matrix,thus jeopardizing the potential of using multi-dimensional matrices.In this study,an anisotropic hydroxyapatite-based set of scaffolds is considered as a 3D biomimetic support for bone cells deposition and growth.Measurements of sample-specific flow resistance are carried out using a perfusion system,accompanied by a visual characterization of the material structure.From the obtained results,a subset of three samples is reproduced using 3D-Computational Fluid Dynamics(CFD)techniques and the models are validated by virtually replicating the flow resistance measurement.Once a good agreement is found,the analysis of flow-induced shear stress on the inner B-HA structure is carried out based on simulation results.Finally,a statistical analysis leads to a simplified expression to correlate the flow resistance with the entity and extensions of wall shear stress inside the scaffold.The study applies CFD to overcome the limitations of experiments,allowing for an advancement in multi-dimensional cell cultures by elucidating the flow conditions in 3D reactors.展开更多
基金supported by the European Union’s Horizon Europe research and innovation programme,Zero Emission electric Vehicles enabled by haRmonised circularity,under No.101138034.
文摘Grain size and formation of the Peripheral Coarse Grain(PCG)defect influence the mechanical and crash properties of extruded profiles.Controlling microstructural evolution during the extrusion of 6XXX series aluminum alloys is therefore essential to ensure the performance of structural components.In this work,three profiles with the same nominal geometry were extruded with a die comprising three different bearing geometries to create different extrusion conditions.Each profile was analyzed experimentally to gather data on the microstructure and mechanical properties.Bulge testing revealed that Profile 2,with the thickest PCG layer(490-1150µm),exhibited worse mechanical performance,with a hoop strain at fracture of 0.08 and a peak load of 51.5 kN,compared to Profiles 1 and 3,which had higher hoop strains(0.13 and 0.14)and peak loads(56.1 and 57.6 kN,respectively).Finite Element Method(FEM)simulations of the extrusion process were carried out using Qform Extrusion UK with a post-processing subroutine developed and implemented to calculate additional parameters such as the stored energy,percentage dynamic recrystallization,grain size,and PCG formation based on standard output parameters from the simulation including strain,temperature and strain rate.The simulation demonstrated that the highest strain rate(40-220 s^(-1))and stored energy(150,000-440,000 J m^(-3))in Profile 2 led to the thickest PCG layer.Based on these results,the proposed predictive model was validated against experimental data,demonstrating high accuracy in predicting PCG thickness and grain size while effectively capturing the influence of process parameters on microstructural evolution.
文摘An innovative approach was introduced for the development of a AA6063 recrystallization model.This method incorporated a regression-based technique for the determination of material constants and introduced novel equations for assessing the grain size evolution.Calibration and validation of this methodology involved a combination of experimentally acquired microstructural data from the extrusion of three different AA6063 profiles and results from the simulation using the Qform Extrusion UK finite element code.The outcomes proved the agreement between experimental findings and numerical prediction of the microstructural evolution.The trend of the grain size variation based on different process parameters was accurately simulated,both after dynamic and static recrystallization,with an error of less than 25% in almost the whole sampling computations.
基金funded by FAR 2019 Interdepartmental Grant,titled‘Microfluidics-based 3D cell culture models for bone regen-eration’awarded by the University of Modena and Reggio Emilia.Grant number:not availableThis work has been partially sup-ported by the project MIUR Progetti di Ricerca di Rilevante Interesse Nazionale(PRIN)-Bando 2017 Prot.2017RKWNJT。
文摘In the field of bone tissue engineering,particular interest is devoted to the development of 3D cultures to study bone cell proliferation under conditions similar to in vivo ones,e.g.by artificially producing mechanical stresses promoting a biological response(mechanotransduction).Of particular relevance in this context are the effects generated by the flow shear stress,which governs the nutrients delivery rate to the growing cells and which can be controlled in perfusion reactors.However,the introduction of 3D scaffolds complicates the direct measurement of the generated shear stress on the adhered cells inside the matrix,thus jeopardizing the potential of using multi-dimensional matrices.In this study,an anisotropic hydroxyapatite-based set of scaffolds is considered as a 3D biomimetic support for bone cells deposition and growth.Measurements of sample-specific flow resistance are carried out using a perfusion system,accompanied by a visual characterization of the material structure.From the obtained results,a subset of three samples is reproduced using 3D-Computational Fluid Dynamics(CFD)techniques and the models are validated by virtually replicating the flow resistance measurement.Once a good agreement is found,the analysis of flow-induced shear stress on the inner B-HA structure is carried out based on simulation results.Finally,a statistical analysis leads to a simplified expression to correlate the flow resistance with the entity and extensions of wall shear stress inside the scaffold.The study applies CFD to overcome the limitations of experiments,allowing for an advancement in multi-dimensional cell cultures by elucidating the flow conditions in 3D reactors.
