Local Strength Research Articles

Effect of heat treatments on inhomogeneous deformation of the melt-pool structure of Al–Si alloy manufactured via laser powder bed fusion

Laser powder bed fusion (L-PBF) is an additive manufacturing technology widely applied to the manufacture of metallic parts. The L-PBF processed aluminum-silicon (Al–Si) cast-type alloy components exhibit an anisotropic tensile ductility. In this study, we investigated the influence of heat treatments on the microstructural features of an Al–12%Si binary alloy fabricated via L-PBF and the associated inhomogeneous deformation of its melt-pool structure, which contributes to the resulting anisotropic tensile ductility. The mechanical inhomogeneity of the melt-pool structure and the change induced by annealing at various temperatures (300 and 530 °C) were characterized using microscale digital-image correlation analyses of scanning electron microscopy images obtained in situ during tensile deformation and nanoindentation hardness mapping. In the specimen fabricated via L-PBF, the high strain was concentrated at the locally coarsened microstructure (the soft region) along the boundaries of the melt pools rather than at the refined solidification microstructure (the hard region) within the melt pools. The localized strain varied depending on the geometrical relation between the orientation of the melt-pool boundary and the tensile direction, thus contributing to the anisotropic tensile ductility. This tendency appeared less pronounced in the specimen annealed at 300 °C, which exhibited a slightly homogenized melt-pool structure. The reduced strain localization is associated with a reduced difference in local strength between the melt-pool boundary (soft region) and the melt-pool interior (hard region). The slight homogenization of the melt-pool structure emphasized the effect of grain morphologies in the α-Al matrix on the inhomogeneous deformation within melt pools. In the specimen annealed at 530 °C, which exhibited a homogenized α-Al/Si two-phase microstructure, the uniformly distributed Si phase would be responsible for the homogenous deformation, resulting in an isotropic tensile ductility. This study advances our understanding of the correlation between the melt-pool structure and the deformation behavior of Al–Si alloys processed using L-PBF, which provides new insights for controlling the ductility by post-processing.

Lateral holding behaviour of torpedo piles in spatially variable soil: Development of a probabilistic design approach

Offshore torpedo piles are increasingly being utilised in deepwater oil and gas development as part of a taut-leg mooring system. As these piles commonly experience inclined loading in service, accurately determining their lateral holding capacity is crucial. Despite the fact that natural soil characteristics exhibit significant spatial variability, existing studies are mostly deterministic in nature. This paper presents probabilistic analyses of the lateral holding capacity of torpedo piles, explicitly considering the spatial variability of soil shear strength. Large deformation finite element calculations are combined with three-dimensional random field generation in a Monte Carlo framework. The results show that while spatial variability does not apparently alter the failure mechanism of laterally loaded torpedo piles, it significantly influences their holding capacity. The routine deterministic calculation, neglecting spatial variability, would probably yield unconservative estimates. To address this challenge, a probabilistic Broms method is developed, which enables engineers to produce lateral holding capacity estimates with varying confidence levels, using local strength data rather than central tendency. Furthermore, endeavours are also made to calibrate the safety factor, extensively employed in deterministic design practices, from a probabilistic perspective, providing practicing engineers with a viable alternative in scenarios where a local strength profile is unavailable.

Memristive Control of Plasmon-Mediated Nonlinear Photoluminescence in Au Nanowires.

Nonlinear photoluminescence (N-PL) is a broadband photon emission arising from a nonequilibrium heated electron distribution generated at the surface of metallic nanostructures by ultrafast pulsed laser illumination. N-PL is sensitive to surface morphology, local electromagnetic field strength, and electronic band structure, making it relevant to probe optically excited nanoscale plasmonic systems. It also has been key to accessing the complex multiscale time dynamics ruling electron thermalization. Here, we show that plasmon-mediated N-PL emitted by a gold nanowire can be modified by an electrical architecture featuring a nanogap. Upon voltage activation, we observe that N-PL becomes dependent on the electrical transport dynamics and can thus be locally modulated. This finding brings an electrical leverage to externally control the photoluminescence generated from metal nanostructures and constitutes an asset for the development of emerging nanoscale interface devices managing photons and electrons.

Local relaxation of residual stress in high-strength steel welded joints treated by HFMI

This research studies the influence of high-peak loads on local relaxation of residual stress and fatigue damage in high-strength steel welded joints treated by high-frequency mechanical impact (HFMI) treatment. The joint behavior is simulated with elastic–plastic finite element analyses that account for the combined effect of geometry, residual stress, and material properties. This simulation uses two treated geometry models: with or without surface roughness on HFMI groove, and two material properties: S690QL and AH36 structural steels. The results show that surface roughness and load history, including high-peak loads, significantly influence fatigue response. It is revealed that the model neglecting the surface roughness cannot represent the amount of residual stress change and fatigue damage at less than 100 µm depth from the surface. In addition, the local yield strength in the HFMI-treated zone affects the plasticity behavior near the surface imperfection under the high-peak loads, which provides comparatively different fatigue damage between S690QL and AH36 in some cases. As a result, this study provides the further understanding needed to develop a robust modeling approach to the fatigue life estimation of HFMI-treated welds subjected to high-peak loads.

Study of Local Strength of Tail Rotor Blade under Ground and Flight Loads

Study of Local Strength of Tail Rotor Blade under Ground and Flight Loads

Aerobic exercise training combined with local strength exercise restores muscle blood flow and maximal aerobic capacity in long-term Hodgkin lymphoma survivors.

It is unclear whether muscle blood flow (MBF) is altered in long-term Hodgkin lymphoma (HL) survivors. We tested the hypothesis that 1) MBF response during mental stress (MS) is impaired in long-term HL survivors and 2) aerobic exercise training combined with local strength exercise (ET) restores MBF responses during MS in these survivors. Eighteen 5-year HL survivors and 10 aged-paired healthy subjects (HC) were studied. Twenty HL survivors were randomly divided into two groups: exercise-trained (HLT, n = 10) and untrained (HLUT, n = 10). Maximal aerobic capacity was evaluated by a cardiopulmonary exercise test and forearm blood flow (FBF) by venous occlusion plethysmography. MS was elicited by Stroop color and word test. ET was conducted for 4 mo, 3/wk for 60 min each session. The aerobic exercise intensity corresponded to anaerobic threshold up to 10% below the respiratory compensation point. The strength exercises consisted of two to three sets of chest press, pulley and squat exercises, 12-15 repetitions each exercise at 30-50% of the maximal voluntary contraction. Baseline was similar in HL survivors and HC, except peak oxygen consumption (peak V̇o2, P = 0.013) and FBF (P = 0.006) that were lower in the HL survivors. FBF responses during MS were lower in HL survivors (P < 0.001). ET increased peak V̇o2 (11.59 ± 3.07%, P = 0.002) and FBF at rest (33.74 ± 5.13%, P < 0.001) and during MS (24 ± 5.31%, P = 0.001). Further analysis showed correlation between the changes in peak V̇o2 and the changes in FBF during MS (r = 0.711, P = 0.001). In conclusion, long-term HL survivors have impaired MBF responses during MS. ET restores MBF responses during MS.NEW & NOTEWORTHY Long-term Hodgkin lymphoma (HL) survivors have impaired muscle blood flow responses during mental stress and decreased maximal aerobic capacity. Supervised aerobic exercise training combined with local strength exercises restores muscle blood flow responses during mental stress and maximal aerobic capacity in these survivors. These findings provide evidence of safety and effectiveness of exercise training in HL survivors. Moreover, they highlight the importance of exercise training in the treatment of this set of patients.

Age Trajectories of the Structural Connectome in Child and Adolescent Offspring of Individuals With Bipolar Disorder or Schizophrenia

BackgroundOffspring of parents with severe mental illness (e.g., bipolar disorder or schizophrenia) are at elevated risk of developing psychiatric illness owing to both genetic predisposition and increased burden of environmental stress. Emerging evidence indicates a disruption of brain network connectivity in young offspring of patients with bipolar disorder and schizophrenia, but the age trajectories of these brain networks in this high-familial-risk population remain to be elucidated. MethodsA total of 271 T1-weighted and diffusion-weighted scans were obtained from 174 offspring of at least 1 parent diagnosed with bipolar disorder (n = 74) or schizophrenia (n = 51) and offspring of parents without severe mental illness (n = 49). The age range was 8 to 23 years; 97 offspring underwent 2 scans. Anatomical brain networks were reconstructed into structural connectivity matrices. Network analysis was performed to investigate anatomical brain connectivity. ResultsOffspring of parents with schizophrenia had differential trajectories of connectivity strength and clustering compared with offspring of parents with bipolar disorder and parents without severe mental illness, of global efficiency compared with offspring of parents without severe mental illness, and of local connectivity compared with offspring of parents with bipolar disorder. ConclusionsThe findings of this study suggest that familial high risk of schizophrenia is related to deviations in age trajectories of global structural connectome properties and local connectivity strength.

Interconnections between local Schumann resonances and episodes of kidney disease

The aim of the study was to evaluate the interconnections between local Schumann resonances of the Earth’s magnetic field and episodes of kidney disease. Materials and Methods: Study participants included 716 males and 624 females who had episodes of kidney disease during the period of 1 January 2021 to 31 December 2021 and attended the Department of Nephrology at the Hospital of Lithuanian University of Health Sciences, Kauno klinikos. Time varying magnetic field data was collected at the magnetometer site located in Lithuania. Results and Conclusions: The study results support the hypothesis that the Earth’s magnetic field has a relationship between the number of nephrology patient hospitalizations per week and the average weekly local Schumann resonances strength in different frequency ranges. Working hypotheses are proposed for the mechanisms of the influence of the Earth’s electromagnetic field on kidney function: а) quantum mechanical features of the atomic composition of renal tissue molecules determine a kidney-specific reaction; b) cyclotron resonance mechanism; c) resonant response of cells of morphological structures of kidney tissue to external bioactive frequencies in the range of 6-8 Hz; d) mechanism of indirect influence of blood as a magnetically saturated medium.

Optimizing Energy Consumption in 5G HetNets: A Coordinated Approach for Multi-Level Picocell Sleep Mode with Q-Learning

Cell standby, particularly picocell sleep mode (SM), is a prominent strategy for reducing energy consumption in 5G networks. The emergence of multi-state sleep states necessitates new optimization approaches. This paper proposes a novel energy optimization strategy for 5G heterogeneous networks (HetNets) that leverages macrocell-picocell coordination and machine learning. The proposed strategy focuses on managing the four available picocell sleep states. The picocell manages the first three states using the Q-learning algorithm, an efficient reinforcement learning technique. The associated macrocell based on picocell energy efficiency controls the final, deeper sleep state. This hierarchical approach leverages localized and network-wide control strengths for optimal energy savings. By capitalizing on macrocell-picocell coordination and machine learning, this work presents a promising solution for achieving significant energy reduction in 5G HetNets while maintaining network performance.

External characteristics of cardio-strength load based on local exercises and heart rate response during its performance

In modern health-enhancing physical culture the use of complex training sessions with successive tasks solving is mainly provided and almost no attention to complex training sessions with parallel task solving. In this regard, it is important to find out the possibility of building training sessions that would allow influencing the cardio respiratory system through the use of strength exercises. The purpose of the study is to explore the characteristics of the load and heart rate changing in complex cardio-strength training sessions with parallel task solving. Experimental total training sessions included a warm-up (10-12 min) and 6 local strength exercises divided into three pairs (biceps - triceps, deltoid - latissimus dorsi, rhomboid - pectoral muscles) performed as circuit training. The duration of cardio- strength sessions – 30 min., intensity – 12 RM, repetition – 4, rest – changing exercises. A 62 years old man with high physical fitness for this age took place in a research. The heart rate study was carried out by the POLAR cardio-tracker. The sound recording of the exercise commentary was simultaneously activated with the heart rate sensor. This made it possible to study the duration of exercises, rests and heart rate during each exercise. Research has shown it is possible to ensure a cardiovascular reaction appropriate for cardio training by using strength exercises. But it requires certain resistance, repetition and rest between exercises at the training session. It is advisable to call such loads as cardio-strength loads. A person is able to provide the necessary duration of exercises and rests in such training sessions without a clock or sound leader. The current heart rate during certain cardio-strength exercise is determined by the complex, ambiguous interaction of several factors. For loads of 1/3 of 12 RM (4 repetitions per set) the most impotent is the initial position. In the initial position the most influential is the body position while performing exercises (lying, sitting, bending over and standing); the activity of the synergist muscles is also important here. In addition, the heart rate reaction depends on a resistance, the preliminary exercise and the activity during the changing exercises.

The Violent Legacy of Fascism: Evidence From Italy

Can legacies of fascism threaten democracies with political violence? Democracies aim to peacefully manage incompatible interests in a society. Yet, few democracies avoid violence altogether. Legacies of fascism may re-emerge because local networks can transfer their ideational tenets - supremacist identities and anti-democratism ( know what), violent practices ( know how), and paramilitary networks ( know whom) - to the new generations. Thanks to an original subnational dataset, we study if the Italian fascist movement that emerged in the 1920s affected political violence in the 1970s–1980s. The local strength of the fascist party before the institutionalization of the fascist regime predicts neofascist political violence more than forty years later. New catalysing events facilitate the resurfacing of local fascist legacies: when a Minister of Interior is appointed, we observe higher levels of neofascist violence in provinces where the early presence of the fascist party was stronger.

Revealing the grain boundary effect on interfacial adhesion in polycrystal Fe/Ni interfaces by using a multi-scale CZM-CPFEM approach

In layered structure, interface plays a significant role in property improvement, whereas its multiple factors at various length scales restricted further understanding. Previous research found a novel grain boundary (GB)-interface interaction: crack initiation locally occurred at the junctions between pre-existing GBs and interface. This leads to decreased interfacial strength. To clarify the mechanisms of such GB-interface interaction, the present study proposed a multi-scale cohesive zone model-crystal plasticity finite element method (CZM-CPFEM) model to investigate the effect of pre-existing GB on intrinsic bonding strength at atomic scale and interfacial stress distribution at micro scale, respectively. At atomic scale, interfacial fracture criteria were modelled according to Molecular Dynamics (MD)-based traction-separation relationships. The accuracy of CZMs was improved by considering both isothermal holding and tilting configuration effects. At micro scale, a practical interfacial microstructure was used to construct CPFEM models. Tensile simulations showed that the local stress concentration occurred at junctions, attributed to the anisotropic plastic deformation behaviours across the GB. On the other hand, weak bonding adhesion at the junction only affects the local crack initiation strength, showing insignificant impacts on the overall interfacial fracture behaviour.

Spiral wave dynamics in a neuronal network model

Spiral waves are spatial-temporal patterns that can emerge in different systems as heart tissues, chemical oscillators, ecological networks and the brain. These waves have been identified in the neocortex of turtles, rats, and humans, particularly during sleep-like states. Although their functions in cognitive activities remain until now poorly understood, these patterns are related to cortical activity modulation and contribute to cortical processing. In this work, ,we construct a neuronal network layer based on the spatial distribution of pyramidal neurons. Our main goal is to investigate how local connectivity and coupling strength are associated with the emergence of spiral waves. Therefore, we propose a trustworthy method capable of detecting different wave patterns, based on local and global phase order parameters. As a result, we find that the range of connection radius (R) plays a crucial role in the appearance of spiral waves. For R < 20 µm, only asynchronous activity is observed due to small number of connections. The coupling strength ( gsyn ) greatly influences the pattern transitions for higher R, where spikes and bursts firing patterns can be observed in spiral and non-spiral waves. Finally, we show that for some values of R and gsyn bistable states of wave patterns are obtained.

Experimentally Dissociating the Acute Mechanisms of Endplate Fracture Lesions and Schmorl's node Injuries Using a Porcine Cervical Spine Model.

In vitro biomechanical study. This study evaluated the influence of localized trabecular bone strength deficits and loading rate as determinants of Schmorl's node and fracture lesion incidence. The failure load (ultimate compression tolerance (UCT)), loading stiffness, and failure morphology were assessed after acute compression loading and failure. The cartilaginous endplate is vulnerable to injuries such as Schmorl's nodes and fracture lesions. While both injuries are associated with acute compression traumas, the factors that distinguish their incidence are poorly understood. Forty-eight porcine spinal units (domestic hog, 5 - 10 months, ~110kg) were assigned to one of eight experimental groups that differed by initial condition (control, sham, experimentally produced chemical fragility, structural void) and loading rate (3 kN/s, 9kN/s). A servo-hydraulic materials testing system was used to perform acute compression testing until observed failure in the specimen. Post-loading dissection was performed to classify injury morphologies. Between group differences in UCT and loading stiffness were evaluated using a general linear model and injury distributions were evaluated using chi-squared statistics. Schmorl's nodes occurred exclusively in chemical fragility (63%) and structural void groups (37%) and were more prevalent with a 9 kN/s (75%) loading rate, compared to 3 kN/s (25%). In contrast, fracture lesions occurred in all FSUs assigned to the control groups (100%) and the majority of those assigned to the sham groups (92%). No between-group differences were observed for UCT and loading stiffness. Pre-existing strength deficits of the subchondral trabecular bone can alter endplate injury morphology, particularly when coupled with high loading rates, but the localized strength deficits that were associated with Schmorl's nodes did not appreciably influence measured joint properties.

Experimental study on pulsed pneumatic pre-fracturing grouting in sandy and clayey-silty hydrate-bearing sediments

Clayey-silty hydrate reservoirs in the South China Sea (SCS) are characterized by low permeability, poor strength, and weak cementation. In order to improve the injection effect of reservoir stimulation by high-viscosity grout, this paper proposes a pulsed pneumatic pre-fracturing grouting technology to enhance the injectability of grout and improve overall conductivity of hydrate-bearing sediments. In the pulsed pneumatic fracturing experiment, increasing the frequency ƒ results in higher average pneumatic pressure σavg and maximum pneumatic pressure σmax, maintaining elevated pneumatic pressure levels that reduce local soil strength and improve fracturing effectiveness. In addition, the fracture extension range is positively correlated with the pressure and frequency. In a pulsed pneumatic pre-fracturing grouting experiment, this technology outperformed the conventional fracturing grouting. At frequencies of 2.5 Hz, 5 Hz, and 10 Hz, the total extension distance of the grout consolidation body increases by 3.28, 4.43, and 4.71, respectively. Meanwhile, the total weight of the grout consolidation body increased by factors of 1.94, 2.45, and 3.57. Additionally, under high-frequency fracture initiation condition (10 Hz), the average thickness of the grout consolidation body doubled compared to that under low-frequency condition (2.5 Hz). In conclusion, the pulsed pneumatic pre-fracturing grouting technology significantly improved the injectability of high-viscosity grout and the effectiveness of grouting stimulation in sandy and clayey-silty hydrate-bearing sediments.

Abstract 1007: A Novel Heterogeneous Murine Aortic Model Derived From Micro-computed Tomography

Introduction: Strength and structural stability of the aorta primarily comes from collagen that is mostly found in the media layer of the aorta along with elastin. The risk of life-threatening aortic rupture increases in cases of aortic aneurysm diseases due to local deformation and weakening of the aortic wall. How does local structure affect how the aorta responds to stress? We hypothesize that material and geometric heterogeneity affect the local biomechanics of the aortic wall and that the local responses to stress are not necessarily the same as the global response. Our goal is to develop a novel finite element model (FEM) of collagen and elastin behavior in murine aorta derived from high-resolution micro-computed tomography (microCT). This model will allow us to study how the aorta deforms to blood pressure at the local level. Approach: The collagen and elastin from 100 vertical slices of microCT scans of a murine aorta were segmented, smoothed and meshed to create 3D models for FEM and the aortic ring was divided into 8 sections of varying geometry and composition. Local stress-strain relationships were extracted from uniaxial loading conditions. Simulations were conducted where the stiffness of collagen was set equal to (1X) or made stiffer than elastin by a factor of 10 (10X) or 100 (100X). The average Young’s modulus, E, for each section was calculated and used as parameters for FEM of the aortic ring to investigate the global mechanical behavior of the aortic wall. Results/Conclusions: The strains generated in the radial direction are greater than the strains in the hoop direction in each of the 8 heterogeneous sections of the aortic ring. There was significant variability in the E values in the 10X and 100X systems. FEM of a materially uniform aortic ring yielded smaller maximum principal logarithmic strains compared to a ring that was materially heterogeneous. This study provides evidence that local structure and material distribution are important in aortic biomechanics. Pathogenesis of aneurysmal disease is dependent on collagen and elastin turnover. Aneurysm rupture results from mechanical failure: peak wall stress exceeds local tissue strength. This novel method will allow for development of a complex aortic fracture model to study aortic pathologies.

Effect of internal moisture content (IMC) on the CO2 sequestration efficiency of hollow natural fiber (HNF)-reinforced reactive magnesia cement (RMC) composites

The incorporation of minor hollow natural fibers (HNF) can significantly accelerate the CO2 diffusion in reactive magnesia cement (RMC). The CO2 diffusivity in HNF is highly related to its internal moisture content (IMC), which subsequently affects the carbonation process of HNF-RMC, but this is outside the scope of the existing studies. Therefore, this work investigates the effect of IMC on carbonation, strength, and microstructure of HNF-RMC composites. HNF-RMC mortar specimens are dried to different levels of nominal IMC (0–100%), and cured under high CO2 concentration for carbonation. Following the curing, the matrix composition was characterized with varying techniques (QXRD, TGA, FTIR, and acid digestion) for quantifying the CO2 sequestration; the compressive strength at different depths was determined with uniaxial compressive test; the microstructure was examined with SEM/ESEM. The results show that the carbonation depth is increased by three to four times by reducing the IMC to 0%. The effects of varying IMC on local carbonation and strength are distinct in the shallow (0–20 mm) and middle/deep region (20–100 mm). In the shallow region, inadequate CO2 dissolution is the limiting factor, these performances decreased with the increasing desiccation. In the deeper regions, moisture absorption by HNF decreased the CO2 diffusivity, hence the CO2 availability is the limiting factor, and these performances increased with the desiccation. These observations suggest that the understanding that carbonation maximizes at a medium moisture level is not valid in HNF-RMC–controlling the moisture can be important for improving the CO2 sequestration and consequent mechanical strength.

What is the best simulation approach for measuring local density fluctuations near solvo-/hydrophobes?

Measurements of local density fluctuations are crucial to characterizing the interfacial properties of equilibrium fluids. A specific case that has been well-explored involves the heightened compressibility of water near hydrophobic entities. Commonly, a spatial profile of local fluctuation strength is constructed from the measurements of the mean and variance of solvent particle number fluctuations in a set of contiguous subvolumes of the system adjacent to the solvo-/hydrophobe. An alternative measure proposed by Evans and Stewart [J. Phys.: Condens. Matter 27, 194111 (2015)] defines a local compressibility profile in terms of the chemical potential derivative of the spatial number density profile. Using Grand canonical Monte Carlo simulation, we compare and contrast the efficacy of these two approaches for a Lennard-Jones solvent at spherical and planar solvophobic interfaces and SPC/E water at a hydrophobic spherical solute. Our principal findings are as follows: (i) the local compressibility profile χ(r) of Evans and Stewart is considerably more sensitive to variations in the strength of local density fluctuations than the spatial fluctuation profile F(r) and can resolve much more detailed structure; and (ii) while the local compressibility profile is essentially independent of the choice of spatial discretization used to construct the profile, the spatial fluctuation profile exhibits a strong systematic dependence on the size of the subvolumes on which the profile is defined. We clarify the origin and nature of this finite-size effect.

Application of local fatigue strength approach to assess and optimise the impact of deep rolling on the fatigue performance of railway axles

Deep rolling is a frequently used post-treatment process to increase the service life of railway axles. Through the process application, the surface roughness is reduced, the surface is work-hardened and compressive residual stresses are introduced in the near surface region in a controlled manner. These three effects have a positive impact on service life, and in the investigated case of railway axles, the introduced residual stress state constitutes the most significant potential. The compressive residual stresses introduced near the surface, which are responsible for the positive lifetime effect, are inevitably balanced by compensating tensile residual stresses below the surface. Therefore, it is generally challenging to estimate the actual potential of the process application properly. Classical design methods consider only the condition at the surface and are thus not suitable for a surface layer-based analysis. In the present publication, the concept of local fatigue strength is applied for the fatigue strength assessment of deep rolled railway axles. The locally permissible fatigue strength at each surface-layer depth of the railway axle is determined as a function of local properties and compared with the locally occurring load. This allows a proper fatigue design in depth and, at the same time, the estimation of the critical point at which the potential of crack initiation and thus failure occurs. Based on the methodology presented, it is possible to determine the fatigue benefit achieved by deep rolling railway axles considering the influence of various deep rolling parameters, and to further systematically optimise the significant process parameters. An increase in fatigue strength of 4.7 % can be proven by deep rolling the railway axle with reference parameters compared with the not deep rolled state. By applying the proposed optimisation, fatigue strength can be further increased up to 10.4 %.

Remanent Magnetic Field Scanning of Coating‐Graded Hybrid Foams

The manufacturing of hybrid materials such as nickel/polyurethane (Ni/PU) hybrid foams and 3D printed hybrid materials with the aid of electrochemical coating of lightweight structures leads to new materials, which can be used as crash absorbers, but also for lightweight design applications. Optimizing the coating quality of the developed hybrid materials necessitates a characterization on different scales regarding the coating thickness distribution. The ferromagnetic properties of the nickel coating enable a remanent magnetization of the produced hybrid foams and a subsequent measurement of resulting magnetic fields, so that the time‐consumption of a coating distribution determination could be enormously reduced by automating the quantification method. Previous studies have shown, that the local strength of these fields correlates with the deposited mass thus the coating thickness. The here presented automated measurement gives useful information about the homogeneity and the local coating thickness distribution according to an appropriate calibration. In order to optimize the coating quality of the newly developed hybrid materials, improved deposition conditions, as well as semi‐automated characterization methods, are studied to establish a large‐scale industrial production and a higher applicability of hybrid materials in the near future.