Sheet metal blanking process is a manufacturing process that is widely used in sheet metal forming and particularly in the electronics and automotive industries. The outcome and quality of the ...blanked parts are affected by various parameters such as the blanking clearance, the sheet metal mechanical properties and the wear of tools. However, experimental campaigns to assess the effects of these parameters on the process outcome can be prohibitively expensive for the industry. As a result, numerical simulation of the blanking process is becoming increasingly important to gain insight into the process and study these effects.
The present paper provides a novel finite element (FE) simulation procedure to predict the complete blanking cycle including sheet metal cutting, sheet metal springback, punch penetration in die, and stripping phases. A blanking force curve showing the punch force at all phases can thus be obtained. The commercial finite element code ABAQUS® has been chosen to develop this procedure using ABAQUS/Explicit® code for the cutting phase and ABAQUS/Standard® code for the remaining phases. Based on this procedure, the influence of the blanking clearance on the punch force-displacement curve and on the cut edge quality has been studied. The obtained results have been compared to previous literature results and experimental findings.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Cold gas dynamic spraying is a solid-state processing technique that is particularly attractive for surface coatings, 3D near-net shape additive manufacturing, and component repairs with an advantage ...of high-deposition efficiency. This technique has the sustainable potential to change the future industrial and manufacturing environment, especially in the fabrication process of complex flight-critical components that are made of aluminum. This paper investigates the microstructure of aluminum coatings generated onto a commercial Al plate called FORTAL (Al 7075-T6) via cold spraying using helium as the propellant gas. Three Al coatings (pure Al, AlSi10Mg, and Scalmalloy) are compared under a similar deposition condition. The top view of the coating revealed the highest deformation (high flattening) in the case of pure Al powders, whereas both the AlSi10Mg and Scalmalloy powders exhibit less flattening. The cross sections show fine equiaxed grains within the pure Al coating and extremely fine grains for both the AlSi10Mg coating and the Scalmalloy coating, with more extremely refined grains within the Scalmalloy coating. These results suggested an onset of recrystallization within the Al coating that is attributed to the heat generated by the strong plastic deformation. Less thermally activated recrystallization occurred within both AlSi10Mg coating and Scalmalloy coating due to their stronger mechanical properties. The structure rather resulted from the dynamic due to the high strain rate collision. The extremely fine structure is mostly at the powder/powder interface within the Scalmalloy coating and is developed towards the powder region which is also within the AlSi10Mg coating. Better plastic deformation occurred within the AlSi10Mg powder compared to the Scalmalloy powder that have a higher mechanical resistance. Together, these results evidence a limited thermally activated recrystallization within the Al alloys despite the highest deposition condition being used. The pure Al powders can also achieve a state of equiaxed fine grain due to the better plastic deformation.
Experimental and numerical approaches are used to investigate the effect of impact location and different external patch configurations on the low-velocity impact behaviors of repaired CFRP ...laminates. Various external patches with different thicknesses (number of layers) and stacking sequences are considered and those patches are used to repair single side of the damaged laminate plates to improve the impact-resistance. To predict the damage initiation and progression of the repaired CFRP laminates under impact loading, a continuum damage mechanics (CDM) model that combines 3D Hashin damage criteria and cohesive zone model (CZM) is proposed. The corresponding drop-weight impact tests are conducted to experimentally obtain the impact response such as impact force and energy. Numerical impact simulations have been performed to study the effect of impact location during the low-velocity impact behaviors of repaired structures. Parametric studies of patch thickness and stacking sequence are also carried out using the low-velocity impact simulation to analyze their effect on the impact-resistance. Finally, this study provides an optimization cafeteria to identify the important design parameter to perform external patch repair based on the simulation results.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The high temperature gradients experienced during fusion welding lead to a local dilatation and metallurgical transformations that generate inhomogeneous plastic deformation, residual stresses and ...distortions in the welded parts which can affect the service life of the structures. To predict such residual stresses and distortions, finite element analysis is nowadays widely used. This work reports a 3D finite element model for welding simulation. The proposed model is based on semi coupled thermo-mechanical analysis using a double ellipsoidal model of heat source. Firstly, a disk heated in its central zone is investigated. Secondly the validation concerns the simulation of a fully 3D two pass butt weld. The idea in this work concerns the calibration of the heat source parameters with the help of the inverse analysis to improve the heat flow predictions. For the stress analysis, an annealing temperature is introduced to force the material to lose its hardening memory above a given temperature. The predicted residual stresses as well as the predicted distortions are found to be sensitive to theannealing temperature.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•Numerical method is used to identify the CFRP patch design for low-velocity impact.•A surrogate-based optimization is implemented to find optimum design parameters.•Surrogate models are built using ...Diffuse Approximation and design of experiments.•The optimum patch designs enhance the impact-resistance of repaired CFRP laminates.•Robustness of the optimization protocol is confirmed via various parameter analyses.
Display omitted
This study proposes a surrogate-based optimization model of the external patch design for damaged carbon fiber reinforced polymer (CFRP) laminates to improve the impact-resistance. Initially, finite element (FE) models of patch-repaired CFRP laminates constructed using continuum damage mechanics (CDM) approach and cohesive zone model (CZM), those well capture the intra- and inter-laminar damages during the low-velocity impacts, respectively. Experimental measurements of low-velocity impact tests concur with the numerical predictions and validate the FE models. Subsequently, the validated models are used to optimize the design parameters of repair patch, consisting of patch radius, thickness and off-axis angle. The optimum design parameters are identified using the surrogate models which are constructed using Diffuse Approximation and Design of Experiments (DOE). The identified optimum patch configurations significantly enhance the impact-resistance of repaired CFRP laminates by decreasing the impact energy absorption and the delamination surface area. Finally, the robustness of the optimization model is confirmed via error analysis of surrogate model reconstruction, and testing the influence of polynomial basis and weighting functions.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this paper, the low-velocity impact response of patch-repaired CFRP laminates is investigated experimentally and numerically. This study considers various patches of different shapes and sizes ...placed on the single side of the parent laminate plates. In the low-velocity impact simulation, damage development and the failure process of the repaired laminate plates are analyzed based on continuum damage mechanics (CDM) theory which is derived from 3D Hashin failure criteria, and a cohesive zone model (CZM). In order to validate the proposed numerical approach, impact response such as impact force and energy are predicted from simulation. Moreover, the corresponding drop weight impact tests have been performed, and the numerical prediction is in a good agreement with the experimental measurements. Finally, the influence of patch parameters on repair performance has been analyzed according to the delamination surface area and absorbed energy of the repaired laminates from the low-velocity impact simulation. And, an optimal impact-resistance design of the patch repair is obtained based on the finding results.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
To overcome the unworkability of hot work molds in conventional manufacturing, laser additive manufacturing (AM) is widely adopted to print molds/dies with complex internal structures. However, in ...the AM process, some hot work steels easily crack (e.g., H11 and H13 tool steel) or exhibit dissatisfactory wear resistance (e.g., MS1 maraging steel). To tackle this issue, toughened functionally graded metal matrix/ceramic composite materials can be fabricated on existing molds by laser directed energy deposition (L-DED). Contrary to previous studies that clad Co on WC to avoid the decomposition of ceramic, in this work, we innovatively utilized a type of WC-12Co powder with a substructure to accelerate its decomposition and improve the toughness of composites. It was found that the unmelted tens-micrometer-magnitude WC-12Co powder and in situ synthesized nano WC coexist in the laser-deposited H13 steel/WC-12Co composites to act as the reinforcement phase. Particularly, all the brittle phases (WC and FexWxC) are wrapped by soft γ phases, alleviating the coefficient of thermal expansion (CET) mismatch between materials and the residual stress generated by laser AM. Consequently, defect-free deposits with varied WC contents are manufactured by L-DED and exhibit high hardness and superior wear resistance at both room and elevated temperatures due to the second phase and grain refinement strengthening mechanisms. These findings provide a disparate metal matrix composite design route for laser additive manufacturing to improve the toughness of metal matrix/ceramic composite materials and obtain exceptional performance.
Display omitted
•The micro/nano strengthening mechanism of WC is studied in Fe-based WC composite.•The Co-coated WC powder with a large specific surface area promotes the in situ synthesis of nano WC precipitates.•All the brittle strengthening phases are wrapped by the ductile austenite to avoid crack.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper aims to determine the weldability window in magnetic pulse welding, via computational and experimental analysis of the Al/Cu interface material response during the high-speed collision. ...The results reveal that the interface morphologies (straight, various type waves, vortices, cavities) arise from the differences in thermal and kinematic instabilities in between the aluminium side and copper side. The analysis of the percentage of straight and wavy morphologies based on the impact velocity versus impact angle allows to predict the weldability window which is potentially 'L' shaped with a convex shape tendency. Therefore, the proposed Eulerian model is robust enough to accurately predict the interface morphologies, and be used as tool to non-destructively depict the weldability window for an impact welding.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Single and multiple track-ballast impacts are investigated for the CFRP laminates used in train carbodies. Numerical simulations have been performed to study the damage behaviors of CFRP laminates ...during ballast impacts and compressions after ballast impact (CABI). Intralaminar and interlaminar damages are successfully predicted using continuum damage mechanics and cohesive zone model, respectively. It reveals that, for a high-speed ballast impact, delamination occurs during the damage initiation and appears at several interfaces nearby the impacted side of the specimen. After that, fiber breakage and matrix cracking appear, while delamination continuously extends until the failure. Repeated ballast impacts on the same site and different sites of specimens show significant increase of delamination while indicating less intralaminar damage. Furthermore, CABI simulations show that, the residual compression strength decreases in a nonlinear manner with the increase of impact energy. To bear the same impact energy, less detrimental effect is caused when one impact is replaced by two or more impacts.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Poroelastic materials mounted against rigid surfaces often result in partial contact between the two, affecting their mechanical interaction. The surface roughness of cellular materials introduces ...complexity in predicting their behavior due to the interface with partial contact. This interface exhibits a stiffness distinct from the bulk material, which is driven by the surface asperities and the preload. This study conducts compression experiments on an open-cell poroelastic melamine foam, and compares them to finite elements simulations and analytic predictions. The material’s intrinsic stress–strain nonlinearity is accounted for, and an original hyperelastic aging model is proposed to achieve accurate predictions of its compression stiffness across multiple time scales. Predicting the compression stiffness of a macroscopic pyramidal asperity demonstrates a good agreement with the simple analytic solution for an elastic pyramidal geometry. Using a Greenwood–Williamson-like model based on the distribution of asperities of different heights, we propose a method to predict the contact stiffness of a rough surface. Our findings have important implications for understanding and optimizing efficient vibration barriers, resulting from the simple stacking of layers and screens of raw poroelastic materials, a configuration widely adopted in the transportation and civil engineering industries.
•Compressed open-cell melamine foam exhibits a nonlinear and time-dependent reaction force well represented by an aging phenomenon.•Macroscopic pyramidal asperities approach a continuous material behavior despite their complex microstructure.•The contact stiffness of an open-cell foam made from multiple macroscopic asperities can be modeled with the proposed analytical method.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
PDF
