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Bio-based hydrogels formed by the chemically or physically cross-links are promising materials in the biological system. In this paper, we propose a constitutive model within the framework of finite-strain viscoelasticity to investigate the mechanical behaviors of bio-based polyelectrolyte complex (PEC) hydrogels from the ionic complexation of sodium hyaluronate (HA)/chitosan with and without chemical crosslinkers. The structure of the viscoelastic constitutive model consists of a spring and a Kelvin element, in which two softening factors are adopted to represent the states of ionic bonds and bridges in the hydrogels. Based on some constitutive assumptions and through the conventional approach of thermodynamics, the constitutive equation system of the model is derived. Corresponding to the hydrogels with different crosslinker concentrations, the values of material parameters in the model are identified. To show the validity of the model, it is applied to simulate the mechanical behaviors of the hydrogel samples in the uniaxial tensile tests and cyclic loading–unloading tests. It is found that the model predictions can fit the experimental data quite well. Based on the modeling results, some further analyses regarding the effects of softening factors on the response of HA/chitosan hydrogels have also been conducted. • A viscoelastic model is proposed to study the mechanical behaviors of PEC hydrogels. • Two softening factors are adopted to represent the states of ionic bonds and bridges. • Parameters are identified for hydrogels with different crosslinker concentrations. • The mechanical response of PEC hydrogels can be predicted accurately by the model. • The effects of softening factors on the response of PEC hydrogels are analyzed. [ABSTRACT FROM AUTHOR]

Fibrin is a protein polymer that forms a 3D filamentous network, a major structural component of protective physiological blood clots as well as life threatening pathological thrombi. It plays an important role in wound healing, tissue regeneration and is widely employed in surgery as a sealant and in tissue engineering as a scaffold. The goal of this study was to establish correlations between structural changes and mechanical responses of fibrin networks exposed to compressive loads. Rheological measurements revealed nonlinear changes of fibrin network viscoelastic properties under dynamic compression, resulting in network softening followed by its dramatic hardening. Repeated compression/decompression enhanced fibrin clot stiffening. Combining fibrin network rheology with simultaneous confocal microscopy provided direct evidence of structural modulations underlying nonlinear viscoelasticity of compressed fibrin networks. Fibrin clot softening in response to compression strongly correlated with fiber buckling and bending, while hardening was associated with fibrin network densification. Our results suggest a complex interplay of entropic and enthalpic mechanisms accompanying structural changes and accounting for the nonlinear mechanical response in fibrin networks undergoing compressive deformations. These findings provide new insight into the fibrin clot structural mechanics and can be useful for designing fibrin-based biomaterials with modulated viscoelastic properties.

With the development of urban metro systems, shield tunnels that pass through existing bridge pile foundations have become an inevitable engineering problem. Therefore, ensuring the stability of the strata and existing bridge piles during tunnel construction is a common goal in engineering practice. Currently, research on the mechanical responses of strata and existing piles under different conditions of upper-soft and lower-hard composite strata during shield tunneling has not been conducted extensively. This paper presents a numerical simulation of a shield tunnel passing through an existing bridge pile foundation in upper-soft and lower-hard composite strata. Subsequently, the surface subsidence and mechanical responses of a single pile were analyzed and evaluated. Additional stresses generated in the soil by existing bridge piles and the selection of grouting pressure were considered to optimize the driving pressure of the slurry shield. Allowable values were proposed to evaluate the construction disturbances caused by the tunnel excavation. The results show that the disturbance to the soil and existing piles is significantly influenced by the hard-rock height ratio, and the surface subsidence increases when the hard-rock height ratio decreases. The displacement and internal force of a single pile are significantly influenced by the load applied to the pile. This study demonstrates the changes in the mechanical responses of a single pile during shield tunnel boring, and provides in-depth insights into the deformation control caused by shield underpassing structures in upper-soft and lower-hard composite strata.

Biodiesel has emerged as one of the major sources of renewable energy in automotive applications substituting the convention diesel. However, the compatibility of biodiesel and rubber components remains a major concern. Indeed, it is found that biodiesel tends to swell rubber components resulting to their faster degradation. Thus, studies focusing on the compatibility of newly developed biodiesel are essential for rubber durability. Along this line, the main purpose of the present study is to investigate the swelling characteristics of rubber in cottonseed oil biodiesel. Two types of unfilled and filled rubbers are considered: natural rubber (NR) and polychloroprene rubber (CR). For filled rubbers, two carbon black contents are used: 25 and 40 phr. The rubber samples are immersed in conventional diesel fuel, biodiesel and diesel-biodiesel blends for 1000 h at room temperature (25 °C). The evolutions of rubber mechanical properties such as hardness, tensile modulus and tensile strength are investigated as well as the macroscopic stress-strain characteristics. For both rubbers, it is found that the decrease in the mechanical properties becomes more significant as the biodiesel content increases. Finally, a continuum model predicting equilibrium swelling proposed by Ch'ng [S.Y. Ch'ng. Coupling between diffusion of biodiesel and large deformation in elastomers: from experimental investigation to constitutive modeling. Ph.D. Thesis. University of Malaya, Malaysia. 2014] is adopted to simulate the effect of carbon black on the stress-free equilibrium swelling of rubber.

Prestressed concrete cylinder pipe (PCCP) is widely used in hydraulic engineering. The bell‐and‐spigot joint is a weak point along a PCCP pipeline, since damage of joint can affect the operation of the whole pipeline. In this paper, a three‐dimensional numerical model of buried PCCP, considering the simulation of rubber gasket in bell‐and‐spigot joint is established. The fluid–structure coupling of PCCP is accomplished using the Mesh‐based parallel Code Coupling Interface (MpCCI), where the pipe and the surrounding soil are characterized in the software ABAQUS, and the pressurized water is modeled in the software FLUENT. The force and rotation angle at joints of PCCP under different conditions, including surcharge load, loading location, cover depth, and internal pressure, are analyzed. It is shown that the rotation angle of joint exceeds the allowable value, when the surcharge load is greater than 180 kPa. Compared with the effect of surcharge load, the offset distance (i.e., distance between the loading position and the pipe axis) has a greater influence on the development of horizontal displacement and rotation angle. As the offset distance increases, both the horizontal displacement and rotation angle at joints increase first, and they decrease after the peak. [ABSTRACT FROM AUTHOR]

As an important basis for determining the state of the liver, the mechanical responses are associated with many factors, and belong to a complex coupling system. Liver tissue has significantly complicated vascular channels. The vascular diameter, vascular deflection angle and vascular depth are defined as the key characteristic parameters. The influences of these parameters on the mechanical responses were analyzed. On the basis of the real mechanical parameters, the coupled numerical model of blood vessel, blood flow and liver tissue was established. The corresponding mechanical responses are obtained by utilizing the different vascular parameters. The effects of vascular parameters on the differences among the mechanical response difference and high strain modulus were analyzed. It was found that the blood vessels in the central area could reduce the liver mechanical response. The inner diameter parameter had main influences on the regions where the stain was more than 0.1. The mechanical difference is greater with larger inner diameter. The influences of vascular depth are greatest when the vascular depth was in the intermediate value, which would increase the liver mechanical responses. With the increment of vascular deflection angle, the liver mechanical response would also increase, and exceed the mechanical response without blood vessels. The findings after analyzing the influence of vascular parameters will provide a basis for the quantitative studies on the influence of blood vessels. [ABSTRACT FROM AUTHOR]

The paper discusses a perspective of the usage of various types of smart materials to enhance the operational properties of Gas Foil Bearings. The authors, referring to the current investigation on thermomechanical characteristics of the above-mentioned bearing type, have focused on the concept of using Shape Memory Alloys, Piezoelectric Transducers, Thermoelectric Modules and Thermocouples to improve both mechanical and thermal behavior of the bearings. Based on the available literature and the authors' experience, the present work provides an overview of the known and perspective applications of smart materials to Gas Foil Bearings. In particular, a discussion on their capabilities, limitations and effectiveness is conducted, taking into account the unique characteristics and requirements of the studied type of bearings. [ABSTRACT FROM AUTHOR]

Quench and mechanical behaviors are critical issues in high temperature superconducting coils. In this paper, the quench characteristics in the rare earth barium copper oxide (REBCO) pancake coil at 4.2 K are analyzed, and a two-dimensional (2D) axisymmetric electro-magneto-thermal model is presented. The effects of the constituent materials, background field, and coil size are analyzed. An elastoplastic mechanical model is used to study the corresponding mechanical responses during the quench propagation. The variations of the temperature and strain in superconducting layers are compared. The results indicate that the radial strain evolutions can reflect the transverse quench propagation and the tensile hoop and radial stresses in superconducting layers increase with the quench propagation. The possible damages are discussed with the consideration of the effects of the background field and coil size. It is concluded that the high background field significantly increases the maximum tensile hoop and radial stresses in quenching coils and local damage may be caused. [ABSTRACT FROM AUTHOR]

Hypothesis: Amphiphilic Janus nanosheets are plate-shaped, with one hydrophilic and one hydrophobic side; they are expected to assemble at oil-water interfaces. The assembled Janus nanosheets layers at the oil-water interface will exhibit a unique mechanical response under the vertical pressure of a probe. The interfacial behaviors of amphiphilic Janus nanosheets and the morphology of the assembled particle film at an oil-water interface were observed. The dynamic morphologies and force-displacement curves of the oil-water interface covered with amphiphilic Janus nanosheets were investigated during the insertion of a cylindrical probe. Amphiphilic Janus nanosheets spontaneously aggregated at the oil-water interface. The morphology of the assembled particle film was controlled by the interfacial nanosheets concentration and can be divided into three regimes: unsaturated, monolayer, and collapsed. The wettability of the probe and the density of nanosheets at the interface played critical roles in the deformation and mechanical response of the oil-water interface under vertical pressure. The presence of amphiphilic Janus nanosheets reduced the stiffness and enhanced the flexibility and deformability of the oil-water interface. The oil-water interface covered with amphiphilic Janus nanosheets could produce larger deformation under a smaller vertical stress. This work not only improves the understanding of the interfacial properties of amphiphilic Janus nanosheets but also provides a method for characterizing nanoparticle layers at oil-water interfaces. [ABSTRACT FROM AUTHOR]

Granular impact phenomena have implications in many areas. A fundamental problem deals with the mechanical response of a granular medium under external loads, such as those derived from the impact of a rigid object on the top of the medium. Here, the load changes its magnitude and intensity during the impact, being also applied in much shorter intervals than those of a static load, where the Boussinesq model is usually valid. This dynamic has been poorly addressed in the literature, a void to which this study aims to contribute, where we measure the pressure distribution transmitted at the bottom of a uniform, dry granular layer under the action of gravitational impacts of a steel sphere of fixed diameter. Exploring different bed thicknesses and drop heights, it is found that the structure of this distribution follows a similar form to the Boussinesq model, which was proposed initially for static conditions. This surprising result opens up several questions and future research challenges that could help validate or refute this model in other scenarios. [ABSTRACT FROM AUTHOR]

To investigate the temporal–spatial temperature field and mechanical response of an orthotropic steel bridge deck during paving with gussasphalt concrete (GAC), in situ monitoring of the Cuntan Yangtze River Bridge in China was conducted during GAC paving, and a finite element method model of the temperature field was established. The test and model show the following: (1) The maximum temperature occur at the paving area mid-span on the steel bridge deck, and the temperature stress of the ribs is non-negligible. (2) The deck in the paving and non-paving areas is mainly subjected to compressive and tensile stresses, respectively. (3) The beam end of the steel box expanded outward, and the deck bulge upward. (4) Based on the analysis of the construction parameters, the paving temperature and width have a greater influence than the paving speed on the stress and deformation fields. In bridge design, the temperature-stress problem caused by high-temperature pavement and the pavement thickness problem caused by the temperature deformation of the deck must be considered. The longitudinal elongation should meet the allowable limits of the corresponding telescopic device. These results can provide a reference for construction workers and maintenance personnel of bridge deck pavement. [ABSTRACT FROM AUTHOR]

Strain rate is a critical parameter in the mechanical application of nano-devices. A comparative atomistic study on both perfect monocrystalline silicon crystal and silicon nanowire was performed to investigate how the strain rate affects the mechanical response of these silicon structures. Using a rate response model, the strain rate sensitivity and the critical strain rate of two structures were given. The rate-dependent dislocation activities in the fracture process were also discussed, from which the dislocation nucleation and motion were found to play an important role in the low strain rate deformations. Finally, through the comparison of five equivalent stresses, the von Mises stress was verified as a robust yield criterion of the two silicon structures under the strain rate effects.

The article presents the results of the analysis of the plastic flow of titanium alloys in the process of the Linear Friction Welding (LFW). LFW is a high-tech process for joining critical structural elements of aerospace engineering from light and hightemperature alloys. Experimental studies of LFW modes of such alloys are expensive and technically difficult. Numerical simulation was carried out for understanding the physics of the LFW process and the formation laws of a strong welded joint of titanium alloys. Simulation by the SPH method was performed using the LS DYNA software package (ANSYS WB 15.2) and the developed module for the constitutive equation. The new coupled thermomechanical 3D model of LFW process for joining structural elements from alpha and alpha + beta titanium alloys was proposed. It was shown that the formation of a welded joint occurs in a complex and unsteady stress-strain state. In the near-surface layers of the bodies being welded, titanium alloys can be deformed in the mode of severe plastic deformation. A deviation of the symmetry plane of the plastic deformation zone from the initial position of the contact plane of the bodies being welded occurs during a process of LFW. Extrusion of material from the welded joint zone in the transverse direction with respect to the movement of bodies is caused by a pressure gradient and a decrease in the alloy flow stress due to heating. The hcp-bcc phase transition of titanium alloys upon heating in the LFW process necessitates an increase in the cyclic loading time to obtain a welded joint. [ABSTRACT FROM AUTHOR]

An impact test method was designed to study the mechanical behaviors of explosive charges in deceleration environments. With this method, the deformation and density variation of explosive charges in various deceleration environments can be obtained by changing the decelerations. The deceleration can be precisely changed without changing the strength of target and the speed of projectile. The high-g deceleration environment was simulated by this method. Then, the factors which influence the mechanical response of cyclotetramethylenete-tranitramine (HMX)-based polymer-bonded explosives (PBXs) in the high-g deceleration environments were investigated. The variation of density, macro size, and meso-damage was obtained. The results showed that the initial density, binder type, and particle size have different effects on the deceleration resistance of HMX-based PBXs, then the mechanism was discussed. The shock sensitivities of the PBXs with different densities, binders, and particle sizes were tested. The relationship between the shock wave safety and the deceleration resistance was discussed. [ABSTRACT FROM AUTHOR]

Dynamic networks composed of constituents that break and reform bonds reversibly are ubiquitous in nature owing to their modular architectures that enable functions like energy dissipation, self-healing, and even activity. While bond breaking depends only on the current configuration of attachment in these networks, reattachment depends also on the proximity of constituents. Therefore, dynamic networks composed of macroscale constituents (not benefited by the secondary interactions cohering analogous networks composed of molecular-scale constituents) must rely on primary bonds for cohesion and self-repair. Toward understanding how such macroscale networks might adaptively achieve this, we explore the uniaxial tensile response of 2D rafts composed of interlinked fire ants ( S. invicta ). Through experiments and discrete numerical modeling, we find that ant rafts adaptively stabilize their bonded ant-to-ant interactions in response to tensile strains, indicating catch bond dynamics. Consequently, low-strain rates that should theoretically induce creep mechanics of these rafts instead induce elastic-like response. Our results suggest that this force-stabilization delays dissolution of the rafts and improves toughness. Nevertheless, above 35[Formula: see text] strain low cohesion and stress localization cause nucleation and growth of voids whose coalescence patterns result from force-stabilization. These voids mitigate structural repair until initial raft densities are restored and ants can reconnect across defects. However mechanical recovery of ant rafts during cyclic loading suggests that-even upon reinstatement of initial densities-ants exhibit slower repair kinetics if they were recently loaded at faster strain rates. These results exemplify fire ants' status as active agents capable of memory-driven, stimuli-response for potential inspiration of adaptive structural materials., Competing Interests: Competing interests statement:The authors declare no competing interest.

Polyethylene glycol chains in two terminals of the naphthalene functional group are threaded into α-cyclodextrin cavities to form the pseudopolyrotaxane (NPR), which not only effectively induces the phosphorescence of the naphthalene functional group by the cyclodextrin macrocycle confinement, but also provides interfacial hydrogen bonding assembly function between polyhydroxy groups of cyclodextrin and waterborne polyurethane (WPU) chains to construct elastomers. The introduction of NPR endows the elastomer with enhanced mechanical properties and excellent room temperature phosphorescent (RTP) emission (phosphorescence remains in water, acid, alkali, and organic solvents, even at 160 °C high temperatures). Especially, the reversible mechanically responsive room temperature phosphorescence behavior (phosphorescence intensity increased three times under 200% strain) can be observed in the mechanical stretch and recover process, owing to strain-induced microstructural changes further inhibiting the non-radiative transition and the vibration of NPR. Therefore, changing the phosphorescence behavior of supramolecular elastomers through mechanical stretching provides a new approach for supramolecular luminescent materials., (© 2024 The Authors. Advanced Science published by Wiley‐VCH GmbH.)

Copyright of Journal of Engineering for Thermal Energy & Power / Reneng Dongli Gongcheng is the property of Journal of Engineering for Thermal Energy & Power and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The long-term stability of a lined rock cavern (LRC) for underground compressed air energy storage is investigated using a thermo-mechanical (TM) damage model. The numerical model is implemented in COMSOL Multiphysics, and TM modeling is verified by the existing analytical solution in the case of no damage. The long-term damage and mechanical responses of the lined cavern are presented. Inhomogeneity and a weak plane are added to the numerical models, and their influences on the stability of the LRC are discussed. Results show that long-term damage occurs within 1 m from the cavern surface. Airtight concrete causes the maximum damage, which occurs in the sealing layer, concrete lining, and host rock, whereas polymer causes the least damage. Compared with the purely thermo-elastic model, the TM damage model obtains larger maximum and minimum principal stresses. In the TM model, the stress of the concrete lining increases and the hoop stress of the host rock decreases with the increase in inclination angle of the weak plane. Moreover, as the inhomogeneity increases, the radial stresses of the concrete and host rock decrease. The maximum hoop stress of the concrete lining in one cycle increases, whereas the maximum hoop stress and maximum hoop strain of the host rock decrease. [ABSTRACT FROM AUTHOR]

Impact caused by bar-shaped falling objects from third-party activities could damage submarine pipelines seriously. In this paper, numerical simulation models of submarine pipelines are established to investigate the damage mechanisms, mechanical behaviors, and energy absorptions of submarine pipelines impacted by bar-shaped objects based on multiple theories and approaches, including elastic-plastic mechanics, geomechanics, elastic foundation beam theory, and finite-element method. The effects of essential physical parameters on the impact behaviors of submarine pipelines are discussed. The results show that the seabed could absorb the highest proportion of impact energy at the final state, but a rock seabed could lead to severe damage to the pipeline. With the increase of the impact velocity, the stress concentration and plastic deformation become serious, as well as the pipeline depression rate and the maximum impact force. High-stress area, plastic deformation area, pipeline depression rate, and absorbed energy proportion increase with the increase of the radius-thickness ratio. The most severe impact damage occurs on the submarine pipelines when a falling object has a tri-prism impact end. The pipeline depression rate increases as the impact angle becomes bigger. An inclined impact could lead to more severe damage if the inclined angle is between 60° and 75°. [ABSTRACT FROM AUTHOR]

Restricted by terrain, a large number of roads and railways often appear along the reservoir line and along the river line, and water level changes are an important factor causing landslides on the banks. At present, most of the researches on slope seepage focus on the unsaturated uniform flow, and the study on the non-equilibrium flow of macropore slope is still lagging behind. In this study, the stability factor of unsaturated seepage flow and unsaturated macropore flow slope was analyzed, and the influence law of the factors including water level rise rate (v), hydraulic conductivity in macropores (Ksf), hydraulic conductivity of the matrix-fracture interface (Ksa), the equivalent diffusion distance between two domains (a), and the volumetric fraction of macropore domain (wf) on the stabilization of slope were analyzed by macropore flow model. The results showed that the water content in the matrix area of the slope was close to saturation in the unsaturated macropore flow, and the water content in the matrix domain was obviously less than that in the matrix domain of the slope under unsaturated macroporous seepage with rise of the water level. The hydraulic gradient of the shallow inward slope was obviously larger than that of the unsaturated large pore flow slope under unsaturated seepage. The moisture content in the matrix domain was much larger than that in the macropore domain (up to 18.9 times) at the same location because the permeability coefficient of matrix domain is much smaller than that of macroporous domain. The stability factor of reservoir bank slope decreased first and then increased with the increase of reservoir water level, and it reached the minimum at the same water level (close to the height of the highest storage level) at the same time. Under the same seepage conditions, the stability of unsaturated macropore flow was weaker than that of unsaturated seepage. Reducing Ksf, a, wf or increasing Ksa made the water exchange between the two regions become slow. As the moisture rapidly migrates to the depth of the slope, it caused the groundwater level to rise and the maximal decrease of slope stability was 17.7%. The influence of v, Ksf and wf slope stability was relatively large and equivalent, while Ksa and a were relatively small and they were about half of the former. [ABSTRACT FROM AUTHOR]

Property of the semiconductors under high pressure is investigated by the density functional theory and paralleled to the foretelling of the linear elasticity theory. In addition, ternary alloys of PbSxSe1-x and PbSxTe1-x lattice matching PbS substrate for x = 0.5 compositions are studied. Furthermore, quaternary alloys PbxSn1-xSyTe1-y lattice matching PbS substrate for x and y = 0.5 compositions are studied. The six independent elastic parameters (Cij) are also calculated. Meanwhile, the results data are analyzed in high pressure. The mechanical response of all alloys to pressures 0, 50, and 100 kbar increases progress to decrease in (Cij) in separate rates. The rapprochement between the calculated results and the available published data for these alloys demonstrate that they had worthy accordance at zero pressure and the results at high pressure may be required as an acceptable reference.

The cold bending method is a type of curved glass curtain wall construction method that has been used in practical engineering for a short time. It has the advantages of simple operation, high efficiency and low cost. However, the mechanical response and properties of glass panes caused by cold bending have not been solved effectively. To study the mechanical response and the properties of cold formed laminated tempered glass panes after applying with a wind load, cold bending and load tests of 9 laminated tempered glass panes were conducted by the orthogonal experimental design method. The effects of cold bending curvature, glass pane thickness and interlayer thickness were considered. In this paper, the response law of cold bending stress to the curvature and the relationship among the influencing factors were analyzed. The variation process of stress, the deflection of cold-formed glass panes under uniform load and the characteristics affected by cold-formed stress and deformation were studied. The results show that the cold bending stress is distributed in a saddle shape, and the curvature has the greatest influence on the cold bending stress, followed by the thickness of the glass panes. The influence of the interlayer thickness is small. The maximum stress appears near the corner of the short side direction adjacent to the cold bending corner. The cold bending stress increases linearly with increasing cold bending curvature. The cold bending stress and deformation have little effect on the change process of the later stage load effect.

The multiscale hybridization of ceramic nanoparticles incorporated into polymer matrices reinforced with hybrid fibers offers a new opportunity to develop high-performance, multifunctional composites, especially for applications in aeronautical structures. In this study, two different kinds of hybrid fibers were selected, woven carbon and glass fiber, while two different ceramic nanoparticles, alumina (Al2O3) and graphene nanoplatelets (GNPs), were chosen to incorporate into a polymer matrix (epoxy resin). To obtain good dispersion of additive nanoparticles within the resin matrix, the ultrasonication technique was implemented. The microstructure, XRD patterns, hardness, and tensile properties of the fabricated composites were investigated here. Microstructural characterization demonstrated a good dispersion of ceramic nanoparticles of Al2O3 and GNPs in the fabricated composites. The addition of GNPs/Al2O3 nanoparticles as additive reinforcements to the fiber-reinforced polymers (FRPs) induced a significant increase in the hardness and tensile strength. Generally, the FRPs with 3 wt.% nano-Al2O3 enhanced composites exhibit higher tensile strength as compared with all other sets of composites. Particularly, the tensile strength was improved from 133 MPa in the unreinforced specimen to 230 MPa in the reinforced specimen with 3 wt.% Al2O3. This can be attributed to the better distribution of nanoparticles in the resin polymer, which, in turn, induces proper stress transfer from the matrix to the fiber phase. The hybrid mode mechanism depends on the interaction among the mechanical properties of fiber, the physical and chemical evolution of resin, the bonding properties of the fiber/resin interface, and the service environment. Therefore, the hybrid mode of woven carbon and glass fibers at a volume fraction of 64% with additive nanoparticles of GNPs/Al2O3 within the resin was appropriate to produce aeronautical structures with extraordinary properties.

The feasibility of a cost-efficient method to produce carbon coated Al-foams in a single-step heating process is investigated. In this context, a dissolution-sintering process for manufacturing metal foams is developed using raw cane sugar as both the space holder material and the carbon generating medium. The structural characteristics of the produced carbon coated Al-foams were evaluated by XRD, Raman and SEM analyses. Static compression tests were conducted to determine the mechanical response of the produced carbon coated Al-foams. The produced carbon coated Al-foams were fully covered with an external carbon layer having a relatively uniform thickness, despite the inherent complex 3D surface of the foam. The carbon deposition process led to a significant increase of the compression strength of the Al-foam. A strain softening behavior was observed for the carbon coated Al-foams attributed to micro-cracking of aluminum carbides. The produced carbon coated Al-foams can potentially be used as a catalyst support structure. [ABSTRACT FROM AUTHOR]

The investigation of concrete structural performance is crucial to maintain the stability of infrastructure. In order to assess structural stability, this work focuses on the development of an integrated framework to detect damaged conditions in the field and analyze their effect on mechanical performance through nondestructive testing (NDT) technology and numerical models. First, a ground penetrating radar (GPR) and an infrared camera work collaboratively to identify the damaged positions of the concrete structure, with parameters calibrated by laboratory experiments. Then, a finite element model is established to study structural mechanical performance based on field conditions and detected results. In addition, the influenced regions induced by local damage are studied under different boundary conditions. As a case study, the devised method was employed in the Nanjing Yangtze River tunnel for stability assessment and disaster prevention. The detected results of the damaged conditions agree well with the actual conditions in the field. Numerical results show that the circumferential stress component is more significant than that observed longitudinally. The effect of local damage on stress implies a positive correlation with the rise of water pressure, in which the maximum stress response to the variation of water level is 45KPa per meter. [ABSTRACT FROM AUTHOR]

Cemented paste backfill (CPB), which is prepared by mixing tailings, binder and water, is widely used in underground mines for waste management and ground control. Since the CPB is delivered into mined-out areas in the form of fluid, a barricade needs to be constructed for retaining it during the process of its filling and hardening. Therefore, the barricade should have enough mechanical stability to ensure the safety of the backfill operation. The behavior of CPB, which is influenced by the thermal, hydraulic, mechanical and chemical (THMC) coupled processes, acts on the barricade and thus affects its mechanical response. In the present study, a numerical model is developed to predict and analyze the barricade mechanical performance in response to the coupled THMC behavior of CPB. The validity of the proposed model is then verified against two field case studies. Acceptable agreement between the model prediction results and in situ monitoring data proves the capability of the developed model in simulating the barricade pressure and displacement. Then, the validated model is used to investigate the effect of filling strategy on the barricade displacement. The obtained results can contribute to a better understanding of the barricade performance under various backfill conditions. [ABSTRACT FROM AUTHOR]

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Xinyang Normal University Natural Science Edition is the property of Journal of Xinyang Normal University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The current study presents the physical and mechanical properties of municipal solid waste (MSW) with different ages of new and old Tabriz landfill. Although there are several theoretical and laboratory methods to investigate the shear strength parameters of MSW, field methods provide more accurate results due to the minimum MSW disturbance and changes, so in this study the shear strength parameters of MSW Tabriz landfill were evaluated using the "Large Scale in Situ Direct Shear Device" with the cross-sectional dimensions 122 × 122 cm. In spite of difficulties related to conducting tests such as potential exposure to various contaminations and the lack of specific equipment in the beginning, it provided more realistic results of the geotechnical behavior of municipal solid waste compared to other methods. Moreover, the in situ unit weight, physical analysis, moisture and organic content at different ages were evaluated to better understand the mechanical response with increase in the age of MSW. The results showed the cohesion and friction angle of 5- and 16-year-old MSW was estimated as 1.17, 2.215 kPa and 31.51°, 21.51°, respectively; According to the results, the shear strength of 5- and 16-year-old MSW is mainly controlled by the friction angle which seems due to the MSW composition as a function of the consumption pattern. The physical analysis of fresh MSW from 2005 to 2017 showed an increase in the fiber content including plastics and textiles. Moreover, studies on MSW mechanical responses over the time revealed a decrease in the shear strength because of the raise in the fiber and plastic content. [ABSTRACT FROM AUTHOR]

Soil reinforcement with natural or synthetic fibers enhances its mechanical behavior in various applications. Fiber-reinforced sands (FRS) can be relatively anisotropic because of the fiber self-weight and the compaction technique. However, the microscopic mechanisms underlying the anisotropy are still poorly understood. This study used a discrete element approach to analyze the microscopic mechanisms underlying the strength anisotropy of FRS due to fiber orientation. Analysis of contact networks revealed that the optimum fiber orientation angle is perpendicular to the main direction of strong contact force in direct shear testing. These fibers produced the largest increase in shear zone thickness, normal force around the fiber body, effective contact area, tensile force along fibers, and energy storage/dissipation. This study is valuable for further understanding of the mechanical behaviors of FRS. [ABSTRACT FROM AUTHOR]

In Ni-based superalloys, it is usually found that borides can strengthen the grain boundaries, thereby resulting in an increase in mechanical strength and high-temperature creep properties. Due to their importance and prevalence in Ni-based superalloys, this study employs first-principles methods to investigate the crystallographic structure, anisotropic elastic response, and electronic properties of the major borides, such as M2B, M5B3 and M3B2 (M: Cr, Mo, W), respectively, which is necessary for the assessment of complex mechanical responses of Ni-based superalloys. The results demonstrate that the studied borides are all thermodynamically and mechanically stable. Among the MxBy binary borides analysed, CrxBy exhibits the largest shear modulus, Young's modulus, and Vicker hardness values, and these properties increase with the increase of B contents. The studied borides display nearly isotropic elastic properties except for W5B3 and W3B2. The electronic structure analysis of MxBy shows that the strong hybridisation between M-d and B-p orbitals leads to these borides exhibiting higher theoretical hardness, and the overlapping peaks of M-d and B-p orbitals move to a lower energy area with the increase of B contents, which leads to the increase of shear and Young's moduli of MxBy. Furthermore, for M3B2 borides, the Cr-B bonds and Cr–Cr bonds are much stronger than the W-B & Mo-B bonds, and W-W & Mo-Mo bonds, respectively, which leads to CrxBy yielding the largest values of elastic moduli. [ABSTRACT FROM AUTHOR]

Effect of size and shape of the additively manufactured Nickel-Titanium (NiTi) alloys on their thermomechanical properties is experimentally studied. Although additive manufacturing is shown as a solution to the difficulties of machining of NiTi shape memory alloys (SMAs), our understanding of the effect of various processing (e.g., laser power, scanning pattern, etc.) and part characteristics (e.g., part geometry) on the resulting properties is not complete. During the SLM fabrication process, various factors influence the properties of the final product. In this study, we investigated the effect of size and shape of the SLM samples on the thermomechanical behavior of the parts. Tensile specimens with different thicknesses and shapes were fabricated for this investigation. The accuracy of fabrication is discussed for all of the specimens. Differential scanning calorimetry (DSC) measurements were conducted to compare the transformation temperatures of specimens with different size and shape. Moreover, tensile tests including loading, unloading, and heating were done for all of the specimens and the mechanical responses were compared with each other. Digital image correlation (DIC) was used for strain measurements as a more accurate strain measurement tool. The transformation temperatures of the fabricated parts were similar for parts with different shapes and sizes. From the mechanical tests, higher strength was observed for the thinner parts in both rectangular and oval specimens. Also, from the mechanical behavior of different shapes, it was observed that the rectangular showed higher critical stress than their equivalent oval specimens. [ABSTRACT FROM AUTHOR]

The appropriate selection of treatment methods for a soft soil subgrade is critical to highway widening projects. In this paper, plane strain conditions are considered in the analysis of prefabricated vertical drains (PVD) and dry jet mixing (DJM) columns. PLAXIS is used to develop the finite element models for the simulation of PVD and DJM treated embankments over soft soils for highway widening projects. The model results include the settlements during and after embankment construction and the lateral displacements of the subgrade. This paper also investigates the working mechanisms when the two subgrade treatment methods are adopted for the widening of embankments over soft soils by analysing the excess pore water pressure distribution in the soft soils. In-situ embankment tests are used to validate the proposed numerical model. The results show that the conventional PVD method causes a soil arching effect in the old embankment and excessive ground disturbance during construction despite the fact that this method can reduce the post-construction soil settlement and the lateral displacement during construction. In comparison, the DJM treatment can greatly reduce the settlement during construction, the settlement and differential settlement after construction, and the lateral displacements. Finally, several techniques are summarised to improve the conventional PVD method, providing practical value for widening highway embankments over soft soils. [ABSTRACT FROM AUTHOR]

Mechanical responsive carbon dots (CDs) is a rising star in the family of carbon materials. However, high pressure devices are essential for observing mechanical responses of carbon dots, but they limit the widespread application of mechanical responsive CDs. Two kinds of CDs were prepared using pyrene derivative (pyrene-1-butyric acid, PyBA) as carbon source, and had fluorescence enhancement via simply grinding. An apparent 20–30 times emission enhancement can be observed after the treatment of grinding because of CDs packed structure and morphology changes. To the best of our knownledge, it is the first example of mechanical responsive CDs with fluorescence enhancement without the stimulation of any complex pressure instrumentation. This simple approach could be extended to other carbon sources with π-conjugated structure for building new intelligentized CDs, and provide new routes for the applications of CDs toward mechanical sensing. [ABSTRACT FROM AUTHOR]

The present work discusses mechanical behaviors of an axially functionally graded (AFG) beam in micro scales subjected to a moving mass. The AFG microbeam is exposed to hygrothermal environments with a uniform temperature rise and a moisture concentration rise. The material properties of AFG microbeam are assumed to vary along the axial direction of the beam according to a power-law function and are temperature dependent. A microbeam model is developed based on a refined first order shear deformation theory (FSDT) in conjunction with the closed-form solution technique, in which the modified couple stress theory is implemented to account for size effect. The minimum energy strategy is applied to derive the eigenvalue equations associated to buckling and free vibrations of the microbeams, while the equations of motion related to the dynamic response are obtained by adoption of Lagrange method and solved using the Newmark- β method. A ceramic-metal AFG microbeam with simply-supported end constraints is taken as a numerical illustration to show the effects of hygrothermal environments, small scale on the mechanical behaviors of AFG microbeams subjected to a moving mass. • Mechanical response of AFG microbeams under hygrothermal environments is investigated. • A refined first order shear deformation theory is used. • Modified couple stress theory is employed. • Temperature-dependent material properties are considered. • The microbeams traversed by a mass. [ABSTRACT FROM AUTHOR]

The three-dimensional finite element model was eatablished with the consideration of load transfer efficiency in the old cement concrete pavement. Considering the arrangement of critical load position, the mechanical responses on the composite pavement surface and at the bottom of the overlay for the old cement concrete were calculated under the aircraft loads of B737-300, B767-300ER and B777-300ER. The maximum value of mechanical response and the location of mechanical response were calculated. The results show that the critical load position of the composite pavement is in the middle of longitudinal seam, and the mechanical response of the composite pavement under the load of the mul-tiaxis landing gear is multi-stress peak mode. With the increasing of the number of axes, the mechanical response is increased significantly, and the superposition effect is more obviously in the multipl-axles. The location of the maximum pavement response at the bottom of the asphalt concrete overlay for the old cement concrete appears near the edge of the tire side. [ABSTRACT FROM AUTHOR]

In annealing of yttria-stabilized tetragonal zirconia (YSTZ), {011}-specific twins and sub-surface defects are often observed, however their effects on the martensitic phase transformation and deformation behavior of YSTZ have never been investigated. In this work, the roles of twin boundaries (TBs) and pre-existing defects in determining the mechanical properties and subsequent deformation mechanisms of YSTZ nanopillars are studied. Using large-scale molecular dynamics simulations, we show that Young's modulus and strength of YSTZ decrease with the increase of TB density, but the ductility of YSTZ pillars increases. Phase transformation behavior is found to be correlated to TB density. The sensitivity of mechanical responses of twinned structures to pre-existing defects is also studied. A competitive mechanism between TB-induced phase transformation and void-induced phase transformation is observed. When the diameter of a pre-existing void is smaller than a critical value, only TB-induced phase transformation occurs, which leads to void-insensitive mechanical properties. [ABSTRACT FROM AUTHOR]

A new generation of bone scaffolds incorporates features like biodegradability and biocompatibility. A combination of these attributes will result in having a temporary bone scaffold for tissue regeneration that mimics the natural cancellous bone. Under normal conditions, scaffolds will be gradually eroded. This surface erosion occurs due to the immersion and the movement of bone marrow. Surface erosion on bone scaffolds leads to changes of the morphology. The mechanical response of the scaffolds due to the surface erosion is not fully understood. The aim of this study is to assess the influence of the dynamic immersion condition on the degradation behaviour and mechanical properties of porous magnesium. In the present work, load-bearing biomaterial scaffolds made of pure magnesium are immersed in simulated body fluids (SBF) with a certain flow rate. Samples with different porosities are subjected to tomography and are used to develop virtual 3D models. By means of numerical simulations, the mechanical properties, for instance, elastic modulus, plateau stress, 0.2% offset yield stress and energy absorption of these degraded samples are collected. The findings are then validated with the values obtained from the experimental tests. Finite element method enables the study on the failure mechanism within the biomaterial scaffolds. The knowledge of how weak walls or thin struts collapsed under compressive loading is essential for future biomaterial scaffolds development. Results from the experimental tests are found in sound good agreement with the numerical simulations. [ABSTRACT FROM AUTHOR]

In order to improve the energy density of polytetrafluoroethylene/aluminum (PTFE/Al), titanium hydride (TiH2) was added as a high-energy additive, and thermogravimetry–differential scanning calorimetry (TG-DSC), quasi-static compression and Split-Hopkinson pressure bar (SHPB) tests were conducted to investigate the chemical reaction mechanism and mechanical response of PTFE/Al/TiH2. The results of TG-DSC indicate that TiH2 first decomposes to form titanium and hydrogen, and titanium reacts with PTFE to produce TiF3, and then with the temperature rising, titanium reacts with carbon and excessive aluminum to generate TiC and Al3Ti. Under quasi-static compression, the strength of PTFE/Al/TiH2 specimens can reach 108.8 Mpa, 14.2% higher than that of PTFE/Al, the special burning flames during the reaction and XRD patterns of the reaction residues consistently indicate that TiH2 has participated in the reaction and react completely, achieving its purpose as a high-energy additive. Under dynamic compression tests, PTFE/Al/TiH2 composites show obvious strain hardening and strain rate hardening effects, and the yield strength and compressive strength are sensitive to strain rates; the established Johnson-Cook (JC) constitutive model can describe the mechanical response of PTFE/Al/TiH2 material well. In addition, the ignition threshold of PTFE/Al/TiH2 drops to 22.78 m/s, less than that of PTFE/Al (23.74 m/s), and the ignition delay time is advanced from 650-700 to 100-150 μs as the impact velocity increase. [ABSTRACT FROM AUTHOR]

Steel arches are widely used to construct main arches in modern concrete bridges. However, the applicability of existing steel arches has certain limitations. To expand the application scope of steel arches and enhance the material utilization rate, this study proposed a calculation and analysis model for a novel steel arch with an adjustable axis. First, the finite element calculation model of the arch structure was established using the finite element software Midas Civil based on Timoshenko beam theory. Second, the sensitive factors that affect the mechanical response characteristics of the novel arch, such as the connection method of the upper chord in the arch section, boundary conditions of the arch springing hinge, and temperature, were thoroughly discussed through calculation and analysis of engineering projects. Finally, the effect of span and width on the arch stability was discussed using the linear elastic analysis method. The mechanical response of the new steel arch was obtained, and the reliability of the calculation results was verified. Results demonstrate that a rigid connection is applicable to the upper chord connection of the arch section, and the two-hinged arch applies to the frame. Temperature changes can lead to obvious deformation and the decrease in temperature indicates a clear stress on the arch. Without considering wind load, the minimum wide-span ratio for the novel arch reaches 1:20. This study can provide a reference for application and calculation analysis of such arches. [ABSTRACT FROM AUTHOR]

Uneven settlement of high-speed railway subgrade leads to the irregularity of high-speed railway line, which seriously affects high-speed train operation. The skylight point of high-speed railway operation is short and the maintenance time is limited. Therefore, how to quickly lift and repair the ballastless track slab in the subsidence section is an urgent problem to be solved in the maintenance of high-speed railways. The two-component non-aqueous reactive polymer material has the advantages of strong expansive force, fast reaction speed, and wide application range, which is extremely suitable for the repair of high-speed railway track slab subsidence and lifting. In this study, the expansion force characteristics of different density polymer materials and the stress-deformation curves at corresponding density are tested in laboratory to propose the mechanical parameters of polymer. Then, a three-dimensional finite element (FE) model of high-speed railway train ballastless-track subgrade is established based on ABAQUS. The mechanical characteristics of CRTS III ballastless track under different repair materials, different elevation, and different density of polymer grouting materials are analyzed. The results show that, under the dynamic load of the train, the stress value of polymer repairing material is less than that of cement slurry, presenting a compressive stress state, which is similar to that of the complete subgrade surface. In addition, within a certain thickness range, increasing the thickness of polymer is beneficial to reducing the difference of stress variation between polymer filling layer and complete pavement. Once beyond this range, the thickness of polymer has little effect on the force variation. [ABSTRACT FROM AUTHOR]

• A parameter design method based on response law of geometric parameters for the piezoelectric actuator is provided. • The lumped-parameter model effectively predicts the dynamic behavior of the PTW wingbeat system and can be validated. • A theoretical foundation for the optimization of the wing-actuator pairing in the flapping wing system is laid. Aiming at the challenge of predicting the dynamic behavior of the flapping wing in the piezoelectric-transmission-wing (PTW) wingbeat system, a lumped-parameter model coupling piezoelectric structural mechanics and flapping-wing aerodynamics is proposed to address the challenge caused by the fluid-structure interaction (FSI). Firstly, a model describing the piezoelectric mechanical response is established, which has the ability to better predict the mechanical response of the piezoelectric actuator under high electric field and low-frequency driving conditions. In order to verify the validity and accuracy, tip deflection, stiffness and blocking force experiments as well as data comparisons are performed to substantiate the findings. Secondly, a comprehensive and reasonable lumped-parameter dynamic model is constructed based on the analysis of the transmission mechanics based on pseudo-rigid-body theory and the improved aerodynamic modeling of the wing, along with the aforementioned piezoelectric mechanical modeling. Thirdly, simulation and dynamic response experiments of the wingbeat system are carried out. Results show that the simulation data are in good agreement with the experimental values, which indicates the accuracy of the model in predicting the dynamic behavior of the flapping wing powered by the piezoelectric actuator. Moreover, some interesting phenomena such as the pitch oscillation of the wing and the dependence of the flapping motion on the driving frequency have been demonstrated in the simulation and the wingbeat experiment, respectively. The research findings of this article offer three types of assistance: (1) providing a parameter design method for piezoelectric actuators to achieve the desired mechanical response; (2) predicting and explaining the dynamic behavior of the PTW wingbeat system; and (3) providing a theoretical foundation for the parameter design and optimization of the wing-actuator pairing in the flapping wing system. [Display omitted] [ABSTRACT FROM AUTHOR]

In-situ observations obtaining mechanical response reveal that no twins form even at the maximum stress of ∼1.4 GPa during loading; nucleation of { 10 1 ‾ 2 } twins occur during unloading. The source of twin nucleation is due to interaction between activated dislocations through slips and pre-existed dislocation, which causes a high stress concentration. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new method of shield initiation using special shaped steel sleeve was proposed. • The mechanical response of the special shaped steel sleeve were analyzed. • The most critical position of the sleeve at the time of initiation was studied. • Field monitoring verified accuracy of numerical calculations. Urban shield tunnel construction is typically affected by limited construction space and the inability to begin from the main line. Conventional lateral initiation solutions result in construction delays and incurs additional construction costs. Hence, based on the Beijing Metro Line 27 project, a novel custom-shaped steel sleeve for lateral initiation is proposed. Numerical simulations are conducted to analyse the stress and deformation characteristics of the steel sleeve during shield initiation. The simulation results, which are validated based on on-site measurements, show that the maximum tensile stress of the shaped steel sleeve structure increases with the shield thrust, and that the average maximum stress occurred at the waist position at the long side of the barrel. However, the stress at the base reduced significantly and a stress concentration occurred at the connection between the sleeve and tunnel portal. The deformation of the sleeve is characterised by a larger long side and a smaller short side owing to the constraint of the tunnel portal. The axial force on the connection bolts below the waist of the sleeve is the highest, whereas the axial force near the tunnel portal is lower. The waist position and the lower section of the sleeve structure are areas where the stress and deformation are weak during the shield initiation of the steel sleeve. Results of engineering test shows that using a shaped steel sleeve for lateral initiation is safe and feasible. However, the waist and bolt connections of the shaped steel sleeve must be scrutinised when used in engineering practice, and standardised construction operations and strengthened monitoring should be implemented. [ABSTRACT FROM AUTHOR]

• Mechanical behaviors of interpenetrating phase composites (IPC) are investigated by experiments and numerical simulations. • Eynergistic effect of the constituent phases has an obvious influence on IPCs in terms of strength, toughness and energy absorption. • The mechanical properties of IPC is affected by the topology and equivalent density. • TPMS-based IPCs achieve outstanding mechanical performance with strength of 84 MPa and SEA of 24.6 J/g. The mechanical performance of triply periodic minimal surface (TPMS)-based interpenetrating phase composites (IPCs) is investigated experimentally and numerically. The TPMS structures are employed as reinforcement phases to improve the mechanical properties of the composites which are fabricated using Polyjet multi-material additive manufacturing. Afterwards, the IPCs as well as their constituent empty phases are uniaxially compressed on a universal electronic machine to investigate the mechanical response and deformation modes. Experimental result shows that G-STPMS IPC outperforms other IPCs with the highest strength of 84 MPa and D-LTPMS IPC exhibits the best energy absorption performance with SEA of 24.6 J/g. The strength and SEA value of TPMS-based IPCs are superior to the sum of the two empty phases up to 497 % and 192 %, respectively. Furthermore, IPCs exhibit excellent damage resistance that abrupt failure or local shear is hardly observed during axial compression. Simulation result reveals the mechanism of the synergistic effect inside IPCs. Moreover, it is proved that the mechanical properties of the IPCs are influenced by the equivalent density. In general, the combination of high toughness and strength makes TPMS-based IPCs promising candidates for energy absorption. [ABSTRACT FROM AUTHOR]

The effects of thermomechanical treatment (cold rolling + tempering) on the microstructure evolution, precipitation behavior, and mechanical properties of the 9Cr3Co3W1Cu martensitic steel (G115) were investigated, by adjusting the cold rolling reduction (0, 20% and 40%), tempering temperature (750 °C and 800 °C) and time (30 min and 120 min). The results indicate that the G115 steel with 20% cold-rolling reduction rate followed by tempering at 800 °C for 30 min exhibits the optimum mechanical response (yield strength (σ s) 899 MPa, elongation (δ) 26%), compared with that of 40% cold-rolled (σ s 812 MPa, δ 17%) and undeformed steels (σ s 670 MPa, δ 15%). The optimum yield strength in 20%-800 °C-30 min steel is attributed to the dislocation strengthening and precipitation strengthening, for the relatively low recrystallization rate and high density Cr 23 C 6 and NbC precipitates, and the good ductility is attributed to the low recrystallization ratio and the uniform microstructure. As a comparison, in 40%-800 °C-30 min steel, a ferrite martensite dual phase structure formed. Due to the hardness difference between the two phases, there may be significant inharmony during the deformation process, leading to premature fracture. • By adjusting the cold rolling reduction (0, 20% and 40%), tempering temperature (750 °C and 800 °C) and time (30 min and 120 min). • The results indicate that the G115 steel with 20% cold-rolling reduction rate followed by tempering at 800 °C for 30 min exhibits the optimum mechanical response (yield strength (σs) 899 MPa, elongation (δ) 26%), compared with that of 40% cold-rolled (σs 812 MPa, δ 17%) and undeformed steels (σs 670 MPa, δ 15%). • The steel produced by 20% cold rolling reduction followed by tempering at 800 °C for 30 min possesses the excellent combination of strength and plasticity at RT (Rm: 1116.7 MPa; δ: 25.5%) and 650 °C (Rm: 474.7 MPa; δ: 25.1%). • The maximum yield strength in 20%-800 °C-30 min steel mainly originates from dislocation strengthening and precipitation strengthening. The steel has the highest dislocation density for the relatively slow recovery rate and high density Cr 23 C 6 and NbC precipitates. • The lower content of recrystallized grains ensures the deformation coordination of the alloy. In addition, the decrease of the Laves phase content reduces the crack nucleation sites. The two factors simultaneously enhance the ductility of the 20%-800 °C-30 min steel. [ABSTRACT FROM AUTHOR]

High temperatures can affect soil performance and alter its engineering behavior. In this study, a series of experiments were carried out on various soil samples provided under different heating conditions (i.e., heated sample and heated clay) to evaluate the various temperatures effects (elevated from 20 to 900 °C) on physical, chemical, mechanical, and mineralogical/microstructural characteristics of clayey samples. The main objective of this study is to investigate the influence of temperature and heating conditions on permeability, unconfined compressive strength, shear wave velocity, weight, color, pH, EC, XRD, and FESEM. The results indicated that dolomite can be broken down into magnesium oxide and calcite, and alpha quartz can be broken down into beta quartz. Calcite minerals decompose into calcium oxide at 900 °C, beta-quartz into alpha-cristobalite, and kaolinite into mullite and gehlenite. The decomposition of water from the hydroxyl structures of minerals in burnt soil is carbonated on the soil's surface up to a temperature of 700 °C; thus, the compressive strength of clay in the temperature range of 500–700 °C is approximately 97% lower than its maximum. At 900 °C, the formation of mullite, gehlenite, and various oxide structures, such as calcium and magnesium oxide, changes the structure of clay to a glassy and amorphous structure. This improves the strength of clay from 0.17 to 3.7 MPa; however, the permeability increases significantly due to the unstable glass structure. The shear wave velocity increased by approximately 2.74 times at 200 °C. It decreased from 300 to 700 °C, then increased to 416.7 m/s at 900 °C. • Temperature influenced permeability, UCS, shear wave velocity, weight, and color. • High temperatures reduce the intensity of calcite, kaolinite, dolomite, albite, and quartz. • At 900 °C, calcite and beta-quartz decompose into calcium oxide and alpha-cristobalite. • At 900 °C, kaolinite decomposes into mullite and gehlenite. • The shear wave velocity decreased from 300 to 700 °C, then increased at 900 °C. [ABSTRACT FROM AUTHOR]