Laser shock peening (LSP) is an advanced surface enhancement technique capable of imparting beneficial compressive residual stresses, thereby improving metal parts’ fatigue resistance and crack ...propagation resistance. This study presents the fatigue behaviour of AISI D2 tool steel samples subjected to LSP with a power density of 15 GW/cm2 and a double laser scanning sequence. The effect of LSP on quasi-static tensile properties was also addressed. The fatigue crack propagation was suppressed in LSP-treated samples when tested at ΔK = 10 MPam. The fatigue strength of treated samples was 32.9% higher compared to untreated samples. The LSP-treated samples have shown a larger fatigue fracture surface area than the as-received (AR) sample. In addition, the tendency to form secondary cracks in the fatigue fracture paths decreased due to LSP treatment. LSP treatment can effectively improve the fatigue resistance and crack propagation behaviour of AISI D2 steel. These improvements are due to significant compressive residual stresses in a superficial layer of the material. The present study provides a reference for improving the mechanical properties of AISI D2 steel by laser shock peening.
•LSP generated a high magnitude compressive residual stress field at depths of 1 mm.•Laser shock peening increased the fatigue strength of AISI D2 tool steel by 32.9%.•Evident retardation of crack growth observed due to compressive residual stresses.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Abstract
Fracture in ice I
h
is simulated with molecular dynamics utilizing two potential fields, TIP4P/Ice and mW, and in different temperature conditions. The simulations produce propagating crack ...speeds over a large range of fracture energies. Terminal crack speed simulated with TIP4P/Ice potential can reach more than 200 m/s befitting experimental results. On the other hand, for mW potential, crack speed is around 5 m/s. The TIP4P/ice model suggests a brittle ice while mW potential describes a much more ductile material. The computational simulations are designed to permit direct comparison with experiments which can be performed in the hereafter. This comparison could provide a sensitive test to interatomic potentials.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
This work aims to study material nonlinearity related to a dual‐phase Steel (DP600) specimen loaded under a tension. Experiment is performed, and then captured data are processed by 3D digital image ...correlation (DIC). It deals with two analyses; firstly, elastoplastic response of material due to tension up to material plastification. Then, the problem is modelled using FEM, considering an isotropic von Mises criterion/hardening behaviour. To obtain comparable numerical results, model is solved using meshless methods. Besides strain fields, load/displacement response is evaluated, and numerical formulations are validated with experimental solution. Second, failure phenomenon due to plasticity is studied since material undergoes its failure. The empirical results rely on DIC, and then, damage model is resolved using Gurson‐Tvergaard‐Needleman (GTN) criterion. As a result, the engineering stress/strain curves are reported. Comparisons are made between DIC and GTN damage model. Promising computational results are verified by DIC results implying that supportive strategy is proficient.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
An image sensing methodology is developed to enable structural integrity monitoring of rotating parts. The proposed approach is based on simultaneously triggering two high-speed cameras in order to ...acquire images of the rotating subject in an apparent fixed position and employing 3D Digital Image Correlation (DIC) thereafter to acquire shape and measure total deformation. A controller was developed to generate the trigger signals at appropriate times and is capable of supporting multiple use cases. The present contribution includes the application of this method to a radio-controlled helicopter's rotor blade under dynamic loading from rotation at 680 rpm and a comparison of this method with previous results.
•Digital Image Correlation was applied to a rotating RC helicopter blade.•Displacements were calculated with negligible rigid rotation between images.•Two different high-speed cameras were successfully combined.•Axis misalignment effects were noticed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Childhood obesity has been associated with increased sodium intake. Nonetheless, evidence linking sodium intake to Body Mass Index (BMI) and Body Fat Mass Percentage (%BF) remains limited, especially ...in the pediatric age group. Therefore, this study aims to investigate whether there is an association between 24 h urinary sodium excretion with BMI and %BF in a sample group of children from the ARIA study. This cross-sectional analysis included 303 children aged 7 to 12 from across 20 public schools in Porto, Portugal. Weight and %BF were assessed using the Tanita™ BC-418 Segmental Body Analyzer. Children's Total Energy Intake (TEI) was estimated through a single 24 h Recall Questionnaire, and urinary sodium and potassium excretion was estimated by a 24 h urine collection. The association of %BF and BMI with 24 h sodium excretion was estimated by a binary logistic regression adjusted for sex, age, physical activity, total energy intake, parental education, and 24 h urinary excreted potassium. There was a significant positive association between higher levels of urinary sodium excretion and higher %BF values, even after adjusting for confounders. However, the same was not observed for BMI. Our findings suggest that higher sodium intake is associated with higher values of %BF among children, regardless of TEI and potassium intake.
This study demonstrates the fabrication of self-aligning three-dimensional (3D) platinum bridges for ammonia gas sensing using gas-phase electrodeposition. This deposition scheme can guide charged ...nanoparticles to predetermined locations on a surface with sub-micrometer resolution. A shutter-free deposition is possible, preventing the use of additional steps for lift-off and improving material yield. This method uses a spark discharge-based platinum nanoparticle source in combination with sequentially biased surface electrodes and charged photoresist patterns on a glass substrate. In this way, the parallel growth of multiple sensing nodes, in this case 3D self-aligning nanoparticle-based bridges, is accomplished. An array containing 360 locally grown bridges made out of 5 nm platinum nanoparticles is fabricated. The high surface-to-volume ratio of the 3D bridge morphology enables fast response and room temperature operated sensing capabilities. The bridges are preconditioned for ~ 24 h in nitrogen gas before being used for performance testing, ensuring drift-free sensor performance. In this study, platinum bridges are demonstrated to detect ammonia (NH
) with concentrations between 1400 and 100 ppm. The sensing mechanism, response times, cross-sensitivity, selectivity, and sensor stability are discussed. The device showed a sensor response of ~ 4% at 100 ppm NH
with a 70% response time of 8 min at room temperature.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Automotive engineering is a very important branch of design and development in mechanical engineering devoted to vehicle manufacturing. It demands solid knowledge focusing on the kinematics and ...dynamics of mechanical systems, either using structural analysis or modelling techniques. In this manuscript, a model based on the application of the fundamentals of the static and dynamic behaviour of the suspension system of a bus vehicle is developed. Therefore, a set of mathematical equations is expanded following the structural dynamic formulations to obtain an analytical solution on natural frequencies and the displacement under an external load. The problem is also solved using the Finite Element Method (FEM) to confirm the analytical results. Equivalent material parameters and boundary conditions were used for the FEM simulation. This work aims to propose a methodology based on modal analysis with a simplified model to predict the dynamic response of an automotive structure.
The need for weight reduction and leaner manufacturing and assembly processes in aircraft construction has led to the pursuit of welding technologies. One such technology that has been considered for ...this application is friction stir welding (FSW). Since it is a solid‐state joining method, it creates high performing joints in a wide range of materials while avoiding overlap lengths and added weight from fasteners, crack stoppers, doublers, etc. However, the adoption of this technology to the assembly of large fuselage shell components is challenging, due to geometric tolerance management requirements. In this paper, a hybrid joining method is proposed for such application, involving FSW and adhesive bonding. Fatigue performance of single lap joints of AA2024‐T3 Al‐Mg‐Cu alloy was assessed and benchmarked against FSW overlap and adhesive bonded joints. Significant strength and ductility increase was achieved through the hybridization of the overlap FSW joints. Fatigue strength of the hybrid joints was also higher than FSW overlap joints, although not as high as adhesive bonded joints.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
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