Deformation Of Layer Research Articles

In-Plane Impact Response of Graded Foam Concrete-Filled Auxetic Honeycombs.

Foam-filled honeycombs have been widely applied due to their excellent load transfer mitigation and energy absorption capacity. In the present study, a layered graded foam concrete-filled auxetic honeycomb was proposed by tuning its overall compression deformation mode to layer-by-layer deformation mode to realize multi-level structural protection. The effect of the honeycomb cell-wall thickness gradient (with an average thickness of 0.25 mm, thickness gradients of 0.30:0.25:0.20, 0.35:0.25:0.15 and 0.40:0.25:0.10, and corresponding positive gradients) and the foam concrete filler density gradient (408:575:848, 848:575:408) on the response mode, load transfer, energy absorption, and Poisson's ratio of the proposed composite was systematically investigated. The results showed that the graded composite exhibited an obvious layered deformation mode and a negative Poisson's ratio effect under relatively low and moderate loading rates (1 m/s, 10 m/s, respectively), especially with the foam concrete density gradient. Under a high loading rate (100 m/s), the graded composite demonstrated progressive collapse initiating from the loading end with a layer-by-layer crushing mode, regardless of the thickness and density gradient. In the response of the composite with a 0.2:0.2:0.2 thickness ratio and a 408:575:848 foam concrete gradient subjected to 1 m/s crushing, the first-layer, second-layer, and third-layer foam concrete absorbed 94.62%, 88.72%, and 86.94% of the total foam concrete energy absorption in the corresponding crushing stage, respectively. Compared with the counterpart homogeneous composites, although the graded composite had an insignificant improvement on energy absorption (less than 5%), it was able to significantly reduce the peak load (as high as 30%) to mitigate the load transfer to the protected structure. The effective Poisson's ratio of the first layer in the composite with positive gradient (408:575:848) increased to -2 then converged to -0.6 under 2 m/s and 10 m/s crushing, and ranged from -0.4 to -0.1 under 50 m/s and 100 m/s crushing, respectively. The effective Poisson's ratio of the middle and bottom layers increased to -2 initially and converged to range -0.4 to -0.1, regardless of the crushing speed. The staged response mode of the graded composite facilitated the realization of multi-level structure protection with significantly reduced peak load transferred to the protected structure and tuned energy absorption.

Illustration of chemical reaction on the flow of viscous fluid in a deformable permeable layer: A numerical approach

In this article, analysis is carried out for the flow of viscous liquid in a deformable permeable layer. Influence of chemical reaction is considered that will affect the flow behavior. The governing equation describes the coupling between the solid deformation, fluid movement and concentration in the porous layer. However, these complex transformed designed problems are numerically examined retaining “Runge-Kutta fourth-order” in coordination with shooting method. Computational results for the numerous parameters on the flow phenomena such as solid displacement profiles are presented graphically. Moreover, the significant finding of the results is; increasing viscous drag retards the momentum within the permeable stratum whereas increasing particle concentration has opposite impact on the solid displacement within the domain.

Spark plasma sintering of Nb/Ti3Al(Si)C2-TiC laminated composites

This work describes novel Nb/Ti3Al(Si)C2-TiC laminated composites fabricated by spark plasma sintering (SPS) at 1250 °C, 50 MPa for 5 min. Preceramic papers filled with Ti3Al(Si)C2 MAX-phase and Nb foils were used as feedstock. Microstructure, phase composition and mechanical properties were evaluated by scanning electron microscopy, X-ray diffraction and three-point bending test, respectively. It was found that the reaction of preceramic paper-derived layers with Nb layers results in the formation of 16.5 µm-thick interlayers mainly composed of columnar Nb-Al intermetallic, Ti-Nb-Si and Nb-Si based phases. The laminated composites showed a brittle-ductile fracture behavior characterized by multiple deflection and branching of cracks at interfaces and plastic deformation of Nb layers. Crack deflection and delamination occur mainly near the interface between the reaction layer and ceramic layer due to the presence of more brittle silicide and carbide phases. The flexural strength of the fabricated composites was ∼350 MPa at 1.5% strain.

Ultrasonic constitutive model and its application in ultrasonic vibration-assisted milling Ti3Al intermetallics

Ultrasonic vibration-assisted technology is widely utilized in the performance research and manufacturing process of metallic materials owing to its advantages of introducing high-frequency acoustic systems. However, the acoustic plasticity constitutive model and potential mechanism, involving Ti3Al intermetallic compounds, have not yet been clarified. Therefore, the Ultrasonic-K-M hybrid acoustic constitutive model of Ti3Al was established by considering the stress superposition, acoustic thermal softening, acoustic softening and acoustic residual hardening effects according to the dislocation density evolution theory and crystal plasticity theory. Meanwhile, the mechanical behavior of ultrasonic vibration-assisted tension (UVAT) and microstructure of ultrasonic vibration-assisted milling (UVAM) for Ti3Al was investigated. Dislocation density to be overcome from initial deformation to failure of Ti3Al was calculated in UVAT and was verified in UVAM. The results indicated that the Ultrasonic-K-M model showed a good agreement with the experimental data. There was an obviously softening phenomenon after introducing the ultrasonic energy field in the Ti3Al whole deformation region, and the degree of softening was positively correlated with amplitude. Furthermore, the maximum reduction ratio in yield strength of Ti3Al was 16 % and the maximum reduction value in ultimate tensile strength was 206.91 MPa. The elongation rose first and then fell as amplitude enlarged, but only as the vibration was applied in the whole deformation region, the elongation was always greater than 14.58 %. In addition, The UVAM process significantly reduced the dislocation density increment to be overcome for Ti3Al material removal by 1.37 times, and promoted dislocation motion and cancellation to make twisted dislocations evolve into parallel dislocations. As the amplitude increased to 4 μm, the depth of the disturbed area of the plastic deformation layer increased by a maximum of 2.5 times.

Theoretical prerequisites for improving durability of fixed rolling bearing joints restored with anaerobic

The paper presents the results of theoretical research of scientific works on determining the durability of fixed rolling bearing joints with restored anaerobic sealants, develops a scheme of angular mixing of the outer ring of the bearing at the deformation of the adhesive layer, and derives the analytical dependence of the absolute elongation of the adhesive layer in operating conditions.

Зносостійкість титанового сплаву ВТ1-0 з модифікованою поверхнею в умовах абразивного впливу

The cost of rebuilding machine parts as a result of wear is enormous and rising every year. At a US symposium on reducing wear in machinery, the general consensus was that wear management is central to solving national problems such as energy conservation, material reduction, and ensuring the reliability and safety of mechanical systems. Nitriding significantly increases the wear resistance of metals and alloys. The formation of chemical compounds in titanium alloys by introducing nitrogen or increasing its concentration limit changes the rate of chemical reactions and the kinetics of oxide film growth, and increases their adhesion to the substrate. This leads to a decrease in the intensity of adhesive node formation and improves the tribological characteristics of titanium alloys. Therefore, it is necessary to study a titanium alloy with a hardened nitrided layer to obtain experimental results to determine the regularity of the influence of diffusion saturation parameters on wear resistance under abrasive conditions. The universal installation "VIPA-1" was used for vacuum ion nitriding in the pulse mode and the formation of diffusion layers on the surface. Technological parameters of vacuum ion nitriding in the pulse mode: temperature - 550°C, pressure - 25-150 Pa, processing time - 10 hours, ratio of reaction gases - 80% Ag + 20% N2. For experimental studies, samples of VT1-0 titanium alloy with dimensions of 30x30 mm and a thickness of 5 mm were used. The surface hardening of the samples was carried out uniformly around the entire perimeter, which ensures a uniform thickness of the diffusion layer. The analysis of the operating conditions of the friction surfaces of most structural elements made it possible to use the installation for bench tests according to the scheme of wear with a free abrasive (Brinell method). Wear tests were carried out on an experimental setup in accordance with GOST 23.208-79 (Fig. 2). The friction process was modelled in the presence of a free, not rigidly fixed abrasive, which coincides with the American standard ASTM C 6568. The experiment was carried out at a sliding speed of 0.158 m/s, a load of 20 kg (with a shoulder of 272 mm) and a friction path of 50 m. Steel 45, hardened to a hardness of 480-500 HB, was used as a reference. The wear body was a disc made of VT1-0 titanium alloy with a diameter of 100 mm and a thickness of 3.5 mm. On the basis of experimental studies, it has been established that the main mechanisms for increasing the wear resistance of titanium alloys as a result of the process of diffusion saturation of the surface with nitrogen during vacuum ion nitriding in the pulse mode are strengthening of the surface layers; creation of a favourable residual stress pattern; change in the patterns of deformation of the surface layers; change in the chemical and adhesive properties of the surface; transfer of diffusing nitrogen atoms into the depth of the matrix during friction due to the tribodiffusion effect. Conclusions. 1. Maximum wear rate of titanium alloy VT1-0 without hardening. 2. The effect of thermocyclic nitriding increases the wear resistance of VT1-0 alloy: in sand - 3 times; in water + sand - 3.5 times; in salt + sand - 2.5 times. 3. The effect of isothermal nitriding increases the wear resistance of VT1-0 alloy: in sand - 4 times; in water + sand - 3.5 times; in salt + sand - 2.5 times.

Finite Element Simulation of the process combination Hammering Turning

In the process combination of Hammering Turning, the workpiece surface is microtextured during machining by means of a multi-axis superimposed oscillation of the cutting tool. These microtextures are formed by plastic deformation of the surface layer in a process phase without material removal. In this paper, the formation of the microtexture in the originally three-dimensional process is investigated in simplified analogue 2D FEM simulations. This therefore only represents the processes and mechanisms directly below the cutting edge. The influence of the tool orientation on the plastic material flow and the formation of the microtexture as well as the residual stresses in the surface layer is investigated.

Paleostress, deformation mechanisms and finite strain related to chocolate-tablet boudinage and folding of a Permian rock salt/anhydrite sequence (Morsleben site, Germany)

Polyphase chocolate-tablet boudinage of competent anhydrite layers in incompetent Permian rock salt of the Morsleben repository (Germany) developed during Triassic/Jurassic graben formation and late Cretaceous graben inversion. The competence contrast between layers and matrix is related to the deformation mechanisms of anhydrite and halite, which have been constrained in the present study using deformation microfabrics and geochemical data. Boudinage implies a finite longitudinal strain of ca. 100% in NNW-SSE direction. There is a clear impact of the layer thickness on both the deformation mechanisms and the shape of anhydrite boudins. Pervasive solution-precipitation creep is the dominant deformation mechanism in thin anhydrite layers (thickness < 15 cm), which are dominated by drawn boudins with aspect ratios ranging from 1.5 to 5.4. Deformation of thick anhydrite layers (thickness > 15 cm) was accommodated by dislocation creep succeeded by localized solution-precipitation, kinking, twinning and fracturing resulting in torn boudins with aspect ratios between 0.5 and 2.0. Halite of the incompetent rock salt matrix deformed viscously under low differential stress (2.0–3.1 MPa). The deformation mechanisms were dislocation creep in form of subgrain formation and strain-induced grain boundary migration. Moreover, close to anhydrite boudins, solution-precipitation creep of halite is indicated by decreased bromide content in halite of necks between brittle torn boudins, which should have precipitated from a fluid phase. Halite in necks of drawn boudins, on the other hand, displays a continuous decrease of bromide content, pointing to predominantly crystal plastic inflow of halite.

Static wetting of a barrel-shaped droplet on a soft-layer-coated fiber.

A droplet can deform a soft substrate due to capillary forces when they are in contact. We study the static deformation of a soft solid layer coated on a rigid cylindrical fiber when an axisymmetric barrel-shaped droplet is embracing it. We found that elastic deformation increases with a decreasing rigid fiber radius. Significant disparities of deformation between the solid-liquid side and the solid-gas side are found when their solid surface tensions are different. When the coated layer is soft enough and the rigid fiber radius is less than the thickness of the coated layer, pronounced displacement oscillations are observed. Such slow decay of deformation with distances from the contact line position suggests a possible long-range interaction between droplets on a soft-layer-coated fiber.

Kinetics of setting between dissimilar crystalline materials under thermo deformation effect

It has been established that the kinetic curves of adhesion (strength increase) are of the sigma type with the displacement period of the second stage relative to the first one. The period of this displacement is determined by starting of a marked metal flow over the micro-protrusion contact sections and its passing on the baton into a harder material under the second kind stresses. Activation of the contact surface of a harder material (corundum) occurs due to a handover of the deformation of the surface layer is plastically deformed micro-protrusions (grains) of the metal due to the effect of the second kind of micro-stresses which were much higher minimum yield strength of a harder material, thereby causing plastic deformation of the latter.

X-Ray Computed Tomography for Failure Mechanism Characterisation within Layered Pouch Cells: Part II

In Part I (), the failure response of a 1 Ah layered pouch cell with a commercially available nickel manganese cobalt (NMC) cathode and graphite anode at 100% state of charge (SOC) (4.2 V) was investigated for two failure mechanisms: thermal and mechanical. The architectural changes to the whole-cell and deformations of the electrode layers are analysed after failure for both mechanisms. A methodology for post-mortem cell disassembly and sample preparation is proposed and demonstrated to effectively analyse the changes to the electrode surfaces, bulk microstructures and particle morphologies. Furthermore, insights into critical architectural weak points in LIB pouch cells, electrode behaviours and particle cracking are provided using invasive and non-invasive X-ray computed tomography techniques. The findings in this work demonstrate methods by which LIB failure can be investigated and assessed.

A deformable CNN architecture for predicting clinical acceptability of ECG signal

The degraded quality of the electrocardiogram (ECG) signals is the main source of false alarms in critical care units. Therefore, a preliminary analysis of the ECG signal is required to decide its clinical acceptability. In conventional techniques, different handcrafted features are extracted from the ECG signal based on signal quality indices (SQIs) to predict clinical acceptability. A one-dimensional deformable convolutional neural network (1D-DCNN) is proposed in this work to extract features automatically, without manual interference, to detect the clinical acceptability of ECG signals efficiently. In order to create DCNN, the deformable convolution and pooling layers are merged into the regular convolutional neural network (CNN) architecture. In DCNN, the equidistant sampling locations of a regular CNN are replaced with adaptive sampling locations, which improves the network’s ability to learn based on the input. Deformable convolution layers concentrate more on significant segments of the ECG signals rather than giving equal attention to all segments. The proposed method is able to detect acceptable and unacceptable ECG signals with an accuracy of 99.50%, recall of 99.78%, specificity of 99.60%, precision of 99.47%, and F-score of 0.999. Experimental results show that the proposed method performs better than earlier state-of-the-art techniques.

An Accurate and Fast Animal Species Detection System for Embedded Devices

Encounters between humans and wildlife often lead to injuries, especially in remote wilderness regions, and highways. Therefore, animal detection is a vital safety and wildlife conservation component that can mitigate the negative impacts of these encounters. Deep learning techniques have achieved the best results compared to other object detection techniques; however, they require many computations and parameters. A lightweight animal species detection model based on YOLOv2 was proposed. It was designed as a proof of concept of and as a first step to build a real-time mitigation system with embedded devices. Multi-level features merging is employed by adding a new pass-through layer to improve the feature extraction ability and accuracy of YOLOv2. Moreover, the two repeated 3 × 3 convolutional layers in the seventh block of the YOLOv2 architecture are removed to reduce computational complexity, and thus increase detection speed without reducing accuracy. Animal species detection methods based on regular Convolutional Neural Networks (CNNs) have been widely applied; however, these methods are difficult to adapt to geometric variations of animals in images. Thus, a modified YOLOv2 with the addition of deformable convolutional layers (DCLs) was proposed to resolve this issue. Our experimental results show that the proposed model outperforms the original YOLOv2 by 5.0% in accuracy and 12.0% in speed. Furthermore, our analysis shows that the modified YOLOv2 model is more suitable for deployment than YOLOv3 and YOLOv4 on embedded devices.

Fault diagnosis of printing press bearing based on deformable convolution residual neural network

&lt;abstract&gt; &lt;p&gt;Rolling bear is a major critical component of rotating machinery, as its working condition affects the performance of the equipment. As a result, the condition monitoring and fault diagnosis of bearings get more and more attention. However, the strong background noise makes it difficult to extract the bearing fault features exactly. Furthermore, regular gradient disappearance and overfit appear in traditional network model training. Therefore, taking the printing press bearings as the research object, an intelligent fault diagnosis method based on strong background noise is proposed. This method integrates frequency slice wavelet transform (FSWT), deformable convolution and residual neural network together, and realizes the high-precision fault diagnosis of the printing press bearings. First, FSWT is used to preprocess the original vibration signal to obtain bearing fault features in the time and frequency domain, reconstruct the signal in any frequency band and describe local features accurately. Second, the ResNet is selected as the base network, and the two-dimensional time-frequency diagrams (TFD) obtained by preprocessing are used as input. For the model that has a poor ability to extract subtle features under strong background noise, the deformable convolution layer is introduced to reconstruct the convolution layer of ResNet, called deformable convolution residual neural network (DC-ResNet). Finally, the effectiveness of this method is verified by using the data sets collected under experimental conditions and actual working conditions for fault diagnosis of the printing press. The results show that the DC-ResNet can classify different bearing faults under strong background noise, and the accuracy and stability are greatly improved, which the accuracy meets 93.90%. The intelligent fault diagnosis with high-precision of printing press bearings under complex working conditions is realized by the proposed method.&lt;/p&gt; &lt;/abstract&gt;

Influences of bus traffic loading on asphalt concrete rutting

ABSTRACT Permanent deformation is the primary failure mode for the asphalt concrete (AC) pavement in urban environment. It is mainly caused by a combination of heavy traffic load, low vehicle speed and channelised traffic. A rut prediction model would therefore be a valuable tool for planning maintenance scheduling and selecting an appropriate asphalt material. This study uses the PEDRO (Permanent deformation in asphalt concrete layers for roads) model to evaluate the rutting performance of flexible pavements in dedicated bus lanes and intersections in urban areas. For this purpose, three road sections along a bus lane in Malmö, Sweden, were selected. To achieve this, AC cores from the road sections were tested using a Shear Box Tester to characterise the asphalt mixtures. Traffic data such as axle load, tyre configuration, speed, and lateral wander distribution of vehicles, and climate data were measured for the selected sections. Field measurements were carried out to assess the structural conditions of the pavements and to measure transverse profiles. This study introduced a procedure for the evaluation and local calibration of the PEDRO rutting model. The results revealed that the prediction of the transverse profiles are generally in good agreement with the rut measurements.

Improved Response Spectrum Method Based on Real-Complex Hybrid Modal Superposition for Base-Isolated Structures

A novel real-complex hybrid modal response spectrum method (RCHM-RSM) based on the modal superposition of the superstructure is proposed for base-isolated (BI) structures in this paper. In contrast to the traditional analysis method, the method can increase the accuracy of the structural response and avoid complex calculations. Additionally, the direct use of the damping matrix of superstructures for BI structures was found to cause an overestimation of the damping effect and consequently underestimate the deformation of the superstructure. Thus, a new scheme is proposed for determining the damping matrix for BI structures, and general expressions of the damping matrix of the superstructure and the damping constant of the isolation layer are presented. Using the proposed method to construct the damping matrix of BI structures, the equivalent load associated with the coupling damping between the structure and support can be determined when the displacement–velocity input model (D–VIM) is adopted. Analytical expressions of structural matrices are presented for a shear-type model of a BI structure, and a numerical investigation is conducted to demonstrate the feasibility and effectiveness of the proposed methods. The results show that the proposed method (RCHM-RSM) has the advantages of simple calculations and high accuracy. The numerical results obtained also confirm that the direct use of the damping matrix of superstructures for the BI structure will underestimate the superstructure response, while the displacement input model (DIM) overestimates the deformation of the isolation layer and underestimates superstructure responses, the analysis results by using D–VIM are consistent with the acceleration input model (AIM), so the D–VIM should be used instead of the DIM.

Investigation on the interaction between corrosion and wear of U68CuCr rail steel with different corrosion periods

The interaction between corrosion and wear of U68CuCr rail steel was investigated. The samples were alternately subjected to the neutral salt spray tests with different corrosion periods (6, 24 and 48 h) and rolling friction wear test for 4 h. The corrosion and wear rates after the corrosion test and wear test were measured, respectively. The surface morphologies of the rail samples after the corrosion test and wear test, and the subsurface morphologies of the rail samples after the last test were observed. The results show that compared to the samples without corrosion, the damage degree of the corroded samples after wear tests became severer, and the wear mass loss and wear rate increased with the number of corrosion-wear cycle. In addition, rolling contact fatigue cracks initiated and propagated at a high angle and the structure of sample surface became unstable after corrosion, leading to easy spalling during the following wear tests compared to the only wear tests without corrosion. Moreover, the plastic deformation layer was destroyed by corrosion and the area of wear pits increased after the interaction test. Therefore, wear was accelerated by corrosion, and the longer is the corrosion period, the more severe is the wear degree. Additionally, regarding to the effect of wear on corrosion, corrosion was accelerated by wear. This is attributed to the facts that (1) the wear pits and delamination on the worn samples provided favorable locations for the deposition of the salt spray solution during the corrosion, and (2) the subsurface and matrix were corroded along rolling contact fatigue cracks to increase the corrosion rate during the corrosion test after wear. This work provides a foundation to the further investigation on the interaction between corrosion and wear of steels.

Thermal-Partial Compression Process: Bypass Route for Multilayer Lamination of Liquid Crystal Polymer-Based 5G Patch Antenna Fabrication

A thermoplastic material lamination process has various problems of layer deformation, misalignment, and delamination. In particular, Liquid Crystal Polymer (LCP) causes more severe interlayer distortion because it needs a higher lamination temperature than other thermoplastic materials. To solve this, three different types of compression methods were proposed to build an LCP-based 5G patch: Batch (BC), Partial (PC), and Thermal-Partial compression (TPC). The antenna was successfully fabricated using the TPC process showing antenna performance at 28 GHz (low band) and 39 GHz (high band). Furthermore, results proved that circuit alignment of the antenna was influenced by lamination temperature and compression order.

Microwave Pyrolysis of Biomass: The Influence of Surface Area and Structure of a Layer

The paper presents the results of experimental research into lab-scale microwave pyrolysis of wood biomass. The influence of the surface area and the structure of the biomass layer on the characteristics of pyrolysis during microwave heating are discussed. We have established that the biomass layer structure and surface area have a significant effect on the yield of pyrolysis gas. The approach of creating artificial deformation of the biomass layer was tested. The elements of artificial porosity made it possible to increase the CO yield by 18% and 32% compared to the pyrolysis of a biomass layer with artificial channels and a uniform layer, respectively. The concentration of H2 was 33% higher compared to the layer without artificial pores and 3% lower compared to artificial channels. The yield of CO2 increased by 25%, and the yield of CH4 doubled. The experiments showed that the distribution of biomass on a half of the bottom of the crucible and the additional porosity of the biomass layer surface effectively increase the yield of the pyrolysis gas components. Recommendations for increasing the efficiency of microwave pyrolysis of biomass were formulated.

Effect of surface severe plastic deformation on microstructure and hardness of Al alloy sheet with enhanced precipitation

The effect of severe plastic deformation on microstructure and hardness of 7075 aluminum alloy sheet presented different results from that of thick samples in previous study. Grains were not refined obviously, and precipitation phases MgZn2 were massively dissolved in the matrix in the region close to the surface. Varied density of dislocations were produced at different depths. The depth of severe plastic deformation layer was 40–70 μm, while the affected depth of hardness was much deeper. The maximum hardness enhancement, 16% increase compared to the core hardness, appeared at about 150–250 μm below surface. The hardness change depended on the competition between the roles of precipitation dissolution and dislocation multiplication.