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Conventional asphalt pavement has a deep surface color and large thermal inertia, which leads to the continuous absorption of solar thermal radiation and the sharp rise of surface temperature. This can easily lead to the permanent deformation of pavement, as well as aggravate the urban heat island (UHI) effect. Cool pavement with a reflective coating plays an important role in reducing pavement temperature and alleviating the UHI effect. It is of great significance to study the influence of temperature on the mechanical response of different types of pavement under vehicle loading. Therefore, this study examined the heat exchange theory between pavement and the external environment and utilized the representative climate data of a 24 h period in the summer. Two kinds of three-dimensional finite element models were established for the analysis of temperature distribution and the mechanical responses of conventional pavement and cool pavement. The results show that in this environmental condition, conventional pavement temperatures can exceed 50 °C under high temperatures in summer, which allows for the permanent deformation of pavement and further affects the service life of asphalt pavement. The temperature difference in a conventional pavement surface between 6 h (24.7 °C) and 22 h (30.2 °C) is much less than that between 22 h (30.2 °C) and 13 h (50.1 °C) in the summer. However, the difference in the vertical displacements of the pavement surface between 6 h and 22 h is much larger than that between 22 h and 13 h. One reason is that the difference in temperature distribution between the morning and night leads to changes in pavement structure stiffness, resulting in significant differences in vertical displacement. Cool pavement has a significant cooling effect, which can reduce the surface temperature of a road by more than 15 °C and reduce the vertical displacement of the pavement by approximately 11.3%, which improves the rutting resistance of the pavement. However, the use of cool pavement will not change the horizontal strain at the bottom of the asphalt base and will not improve the fatigue resistance of asphalt pavement. This research will lay the foundation for further clarifying the difference in the mechanical properties between the two types of pavements in the management and maintenance stage. [ABSTRACT FROM AUTHOR]

In the present study, a semi-empirical modeling of the mechanical response in pile-up mode is obtained by deriving the load-depth relationship during the indentation loading cycle. The advantage compared to the relations previously used is that this new expression is a function of the predictable criterion of the mode of deformation, (hf/hm), which makes it possible to distinguish the sink-in mode from the pile-up mode. A comparison between the proposed expression and the results of the instrumented indentation tests shows excellent agreement. [ABSTRACT FROM AUTHOR]

The macroscopic mechanical behavior and coupling damage mechanism of 2D woven SiC f /SiC ceramic matrix composites (CMC) prepared by chemical vapor infiltration (CVI) process under tension-shear coupling load were experimentally analyzed. At macroscale, the uniaxial tension, uniaxial shear and off-axis tension tests were completed and the results were compared. The tensile modulus and proportional limit have no significant difference with the increase of off-axis angle, while failure strength decreases by 22.3% compared the 45° tensile (165.4 MPa) with the 0° tensile (212.8 MPa). Based on the strain-difference analysis, the coupling damage effect of SiC f /SiC-CMC was characterized. At microscale, the main damage types of SiC f /SiC-CMC during loading were analyzed by scanning electron microscope (SEM), and the corresponding laws between micro damage development and macro mechanical behavior under different loading conditions were revealed by cluster analysis of acoustic emission (AE) signals. The test results show that the micro damage caused by tensile and shear stress components promote each other. The macro mechanical behavior of SiC f /SiC-CMC under complex loading is controlled by basic micro damage forms such as matrix cracking, interface debonding and fiber fracture. The tension-shear coupling load affects the evolution process of the basic damage forms, and then change the macro properties of SiC f /SiC-CMC. [ABSTRACT FROM AUTHOR]

Copyright of Transportation Science & Technolgy is the property of Transportation Science & Technology 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.)

Metal—organic framework-derived materials have attracted significant attention in the applications of functional materials. In this work, the rod-like nickel-based metal—organic frameworks were first synthesized and subsequently employed as the hard templates and nickel sources to prepare the whisker-shaped nickel phyllosilicate using a facile hydrothermal technology. Then, the nickel phyllosilicate whiskers were evaluated to enhance the mechanical, thermal, flammable, and tribological properties of epoxy resin. The results show that adequate nickel phyllosilicate whiskers can disperse well in the matrix, improving the tensile strength and elastic modulus by 13.6% and 56.4%, respectively. Although the addition of nickel phyllosilicate whiskers could not obtain any UL-94 ratings, it enhanced the difficulty in burning the resulted epoxy resin nanocomposites and considerably enhanced thermal stabilities. Additionally, it was demonstrated that such nickel phyllosilicate whiskers preferred to improve the wear resistance instead of the antifriction feature. Moreover, the wear rate of epoxy resin nanocomposites was reduced significantly by 80% for pure epoxy resin by adding 1 phr whiskers. The as-prepared nickel phyllosilicate whiskers proved to be promising reinforcements in preparing of high-performance epoxy resin nanocomposites. [ABSTRACT FROM AUTHOR]

Epoxy asphalt concrete (EAC) has excellent properties such as high strength, outstanding thermal stability, and great fatigue resistance, and is considered to be a long-life pavement material. Meanwhile, the low initial viscosity of the epoxy components provides the possibility to reduce the mixing temperature of SBS-modified asphalt. The purpose of this study is to verify the feasibility of low-emission mixing of SBS-modified epoxy asphalt and to compare the mechanical responses in several typical structures with EAC, in order to perform structure optimization for practical applications of EAC. In this paper, the Brookfield rotational viscosity test was conducted to investigate the feasibility of mixing SBS-modified epoxy asphalt at a reduced temperature. Subsequently, the dynamic modulus tests were carried out on EAC to obtain the Prony series in order to provide viscoelastic parameters for the finite element model. Six feasible pavement structures with EAC were proposed, and a finite element method (FEM) model was developed to analyze and compare the mechanical responses with the conventional pavement structure. Additionally, the design life was predicted and compared to comprehensively evaluate the performance of EAC structures. Finally, life cycle assessment (LCA) on carbon emissions was developed to explore the emission reduction effect of the epoxy asphalt pavement. The results indicate that the addition of epoxy components could reduce the mixing temperature of SBS-modified asphalt by 30 °C. The proper use of EAC can significantly improve the mechanical condition of the pavement and improve its performance and service life. It is recommended to choose S5 (with EAC applied in the middle-lower layer) as the optimal pavement structure, whose allowable load repetitions to limit fatigue cracking were more than 1.7 times that of conventional pavements and it has favorable rutting resistance as well. The LCA results show that in a 25-year life cycle, the carbon emissions of epoxy asphalt pavements could be reduced by 29.8% in comparison to conventional pavements. [ABSTRACT FROM AUTHOR]

Methane hydrate-bearing soils (MHBS) are natural soil deposits that contain methane hydrate (MH) in the pores and have attracted a huge amount of attention as alternative energy to study mechanical properties for realizing large-scale commercial extraction. Especially, MHBS respond to applied loads under complex stress conditions, that is, the effect of the intermediate stress ratio on mechanical characteristics of MHBS. The effect of different values of intermediate stress ratios on the geomechanical responses of pore-filling MHBS was analyzed using the distinct element method (DEM). MH clusters are cemented together as agglomerates of spheres, which fill into the voids of the soil specimen according to the MH saturation. Then, the numerical pore-filling MHBS experimented with different loading paths of the true triaxial tests. Finally, the effects of the intermediate stress ratio on the mechanical characteristics of pore-filling MHBS were analyzed from two aspects, that is, macromechanical responses and micromechanical responses. The results showed that there were correlation analyses between the variations in the strong fabric and principal stresses. The friction angle increased with the intermediate stress ratio until it reached a peak value, and decreased thereafter. The Lade–Duncan criterion is approximately suitable to describe the three-dimensional strength of MHBS. [ABSTRACT FROM AUTHOR]

Metal‐coordination mediated tough hydrogels have been considered as a promising materials for novel utilization in programmable actuation structures. However, the rate‐dependent mechanical behavior attributed to their intrinsic mechanical properties of mixed elasticity and viscosity, imposing a challenge for the realization of controllable deformations. In this work, the effect of stretch rate was incorporated into a variable fractional order model in order to describe and predict the rate‐dependent mechanical response of physically tough hydrogels. Firstly, we provide an iteration algorithm for model estimation and conduct simulations of the stress response under monotonic stretch to verify the applicability of proposed model. The performance of proposed model is compared with the existing model to validate its accuracy. Then, the present model is employed to describe the rate‐dependent stress response under cyclic loading. The change rule of related parameters with stretch rate is also unraveled by the present model, which is further utilized to test the model's predictive ability. Moreover, the physical meaning of variable order is qualitatively explored in conjunction with the evolution mechanism of dynamic bonds. [ABSTRACT FROM AUTHOR]

Copyright of Transportation Science & Technolgy is the property of Transportation Science & Technology 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.)

Formation collapse is one of the common geological hazards for the buried long-distance pipelines. In order to study the mechanical response law of the buried steel pipelines under continuous collapse, experiments and numerical simulations of buried steel pipelines under continuous collapse were carried out, the deformation and stress changes of the buried steel pipelines during continuous collapse were analyzed, and the theoretical calculation results of pipeline mechanics under the collapse geological hazards were checked. The research results show that, in the case of collapse in a small area, the deformation and stress of pipelines increase continuously with the collapse area enlarged, and the displacement and stress in the middle of the pipelines are maximized. When the collapse area is expanded to a certain extent, the soil collapses completely, the pipelines are suspended, the displacement of the pipeline is reduced, the stress of the pipe is released greatly, and the maximum stress position of the pipelines changes from the middle to the point near the collapse boundary of the pipelines. The calculation results of the pipeline stress under the collapse geological hazards are greater than the experimental and simulation values if the friction or cohesion are considered based on the gravity, which are of more guiding significance. Further, the reasearch results could provide effective guidance to pipeline protection.

The present study aims at investigating the effect of organic-modified nickel phyllosilicate (NiPS) particles on the structure–property relationships of epoxy (EP) composites. The organic-modified NiPS particles were synthesized using a facile sol–gel method and subsequently mixed into EP matrix by physical blending to improve its tribological, mechanical and thermal properties. Based on a series of tests and analyses, it was found that organic-modified NiPS particles playing a great role in improving the tribological properties under dry sliding. The steady-state friction coefficient was just decreased moderately, whereas the wear rate was dropped significantly to 0.36 × 10−5 mm3/N·m, showing a reduction up to ca. 95% in comparison with pure EP. According to the analysis of worn surfaces, the main mechanism of wear resistance was discussed. The elastic modulus for the EP composites was increased remarkably while the elongation at break decreased. However, the added organic-modified NiPS particles show a negligible influence on the tensile strength. Moreover, the incorporated NiPS particles could enhance the thermal stability of EP composites, showing the notably suppressed mass loss rate and added residual chars. This study provided a promising way for preparing the high-performance EP composites with organic-modified lamellar particles.

During the operation stage of cold region tunnels, the isotropic surrounding rock in a freeze–thaw circle suffers long-term unidirectional freeze–thaw cycles and gradually transforms into transversely isotropic material, which induces the variation of stress and displacement distribution of cold region tunnels. Aimed at this phenomenon, an analytical solution of mechanical response in cold region tunnels under transversely isotropic freeze–thaw circles induced by unidirectional freeze–thaw damage is proposed. The analytical solution is derived under two different states of the freeze–thaw circle: 1) transversely isotropic and unfrozen state (state TU) and 2) transversely isotropic and frozen state (state TF). In addition, the stress distribution in the lining and surrounding rock with a transversely isotropic freeze–thaw circle is analyzed. The transformation of the surrounding rock in a freeze–thaw circle from isotropic material into transversely isotropic material leads to the increase of stress in the lining, especially for a significant increase under state TF. Finally, the influence of the deterioration coefficient and the degree of anisotropy on the stress distribution in the lining is analyzed. The stress in the lining increases linearly as the deterioration coefficient decreases, while it increases nonlinearly as the degree of anisotropy decreases. The smaller the degree of anisotropy is, the greater the increase rate of the stress is. Moreover, the increase of stress with deterioration coefficient and degree of anisotropy under state TF is much greater than that under state TU. Both deterioration coefficient and degree of anisotropy decrease from 1.0 with increasing unidirectional freeze–thaw cycles suffered by surrounding rock, and, thus, induce the increase of stresses in the lining. In addition, the deterioration coefficient has a greater influence than the degree of anisotropy on the stress in the lining.

The corrosion and mechanical response produced by quenching in the welded joint of a new Nb-doped stainless steel designed by the CALPHAD method and produced by open-atmosphere casting with recycled materials were investigated to contribute to the circular economy and to establish disruptive manufacturing criteria based on metallurgical principles. The steel was initially subjected to solubilization heat treatment and partial solubilization treatment at 1090 °C to obtain an appropriate α/γ balance and carbide solubilization. It was then welded by the SMAW process, quenched, and tempered at three different cooling rates. As a result, a good fit between the phases predicted by the CALPHAD method and those observed by X-ray diffraction and scanning electron microscopy were obtained, with minor differences attributable to the precipitation and diffusion kinetics required for dissolution or nucleation and growth of the phases in the system. The forced air quenching mechanism was identified as providing an α/γ phase equilibrium equivalent to 62/38 as the most effective quenching method for achieving the optimum mechanical and corrosion response, even with the post-weld σ phase and showing superior results to those of the base metal. The outstanding mechanical and corrosion responses resulted from a proper balance of the primary phases in the duplex steel with a precipitation-strengthening mechanism. The damage tolerance obtained by forced air quenching was superior to that obtained by water and air quenching, with a PSE of 24.71 GPa% post-welding.

Mechanotransduction is a molecular process by which cells translate physical stimuli exerted by the external environment into biochemical pathways to orchestrate the cellular shape and function. Even with the advancements in the field, the molecular events leading to the signal cascade are still unclear. The current biotechnology of tissue engineering offers the opportunity to study in vitro the effect of the physical stimuli exerted by biomaterial on stem cells and the mechanotransduction pathway involved in the process. Here, we cultured multipotent human mesenchymal/stromal cells (hMSCs) isolated from bone marrow (hBM-MSCs) and adipose tissue (hASCs) on films of poly(butylene 1,4-cyclohexane dicarboxylate) (PBCE) and a PBCE-based copolymer containing 50 mol% of butylene diglycolate co-units (BDG50), to intentionally tune the surface hydrophilicity and the stiffness (PBCE = 560 Mpa; BDG50 = 94 MPa). We demonstrated the activated distinctive mechanotransduction pathways, resulting in the acquisition of an elongated shape in hBM-MSCs on the BDG50 film and in maintaining the canonical morphology on the PBCE film. Notably, hASCs acquired a new, elongated morphology on both the PBCE and BDG50 films. We found that these events were mainly due to the differences in the expression of Cofilin1, Vimentin, Filamin A, and Talin, which established highly sensitive machinery by which, rather than hASCs, hBM-MSCs distinguished PBCE from BDG50 films.

Conventional billet rolling is being widely used in magnesium (Mg) alloys products, but this method gives rise to biological and environmental problems. The advantages of the short process on sheet fabrication have been widely proved in Mg alloy twin-roll casting (TRC). In this study, an attempt is made to create high-performance Mg alloy sheets via multi-pass unidirectional and cross hot rolling (UR, CR) after TRC for purposes of lowering edge defects and energy consumption. Then, the microstructural and mechanical response of Ce when microalloying AZ31 was observed using UR and CR, respectively. The mechanism of the performance improvement after the AZ31 microalloying is disclosed. In addition, the effect of the rolling parameters on the microstructural and mechanical properties are discussed. Experimental results revealed that the homogenization effect of the AZ31-0.2Ce alloy was the best after being kept at 440 °C for 24 h. The CR-rolled sheet had a more uniform and finer microstructure in the horizontal and center, while for the UR-rolled sheet, it was the opposing edge microstructure. This research is expected to prepare and optimize the microstructural and mechanical properties of microalloying AZ31 in a sheet-rolling process, a material that has important theoretical significance and engineering application value.

Photovoltaic pavement technology was introduced several years ago but has not yet reached commercial maturity, and there are still many technical difficulties to be overcome, such as heat dissipation issues. Using PV cells to generate sufficient energy requires high solar insolation, but high temperatures will also reduce its efficiency.Therefore, this research evaluates the potential of a pavement integrated PV/T system (PIPVT), which incorporates photovoltaic/thermal (PV/T) technology into the roads for power and thermal energy harvesting. While solving the heat dissipation problem of the PV pavement, it can also recover the heat that cannot be used by the PV cells. A unit block of hollow structure 3D printed using plastic material with tempered glass as a protective layer and ABS plastic was used in this paper. A 3D computational finite element model (FEM) developed in ABAQUS was used to analyse the mechanical response of the structure, and a laboratory experiment was conducted to test the influence of the heat dissipation method incorporating water filled pipes on the power generation efficiency of PV cells. The results show that the introduced water circulating pipes had a negligible effect on the mechanical response of PV pavement unit blocks; PIPVT can significantly reduce the solar panel's temperature, and the temperature drop can be as high as 22 °C. According to the results, the primary energy-saving efficiency of PIPVT is estimated to be almost twice that of the conventional PV module. Therefore, this study showed the PIPVT had benefits that went far beyond solar energy generation. [Display omitted] [ABSTRACT FROM AUTHOR]

Because of favorable mechanical properties, deformation resistance and being conducive to environmental protection, honeycomb fabricated plastic pavement slabs are highly recommended these years. At present, most studies focus on the performance of plastic materials, however, the dimension optimization of fabricated plastic pavement slab is rarely mentioned. In this paper, an optimized geometry of the honeycomb pavement slab was determined through finite element analysis. Mechanical response of honeycomb slabs with different internal dimensions and external dimensions were explored. Several dimension factors were taken into consideration including the side length, rib thickness, the thickness of both top and bottom slabs of honeycomb structure and the length, the width and the thickness of the fabricated plastic slab. The results showed that honeycomb pavement slab with 6 cm bottom slab, 12 cm top slab,18 cm side length and 6 cm rib thickness is recommended, additionally, an external dimension of 4 m × 4 m × 0.45 m is suggested. Then, the mechanical responses of this optimized fabricated plastic slab were further investigated. Significance of different influencing factors, including wheel load, elastic modulus of plastic material, base layer thickness, soil foundation modulus and base layer modulus were ranked. [ABSTRACT FROM AUTHOR]

We researched the mechanical unfolding of protein domains in monomeric protein NuG2 and the tandem polyproteins (NuG2)8 and (NuG2)16 using a dual-trap optical tweezers system. By stretching NuG2 and its polyproteins, (NuG2)8 and (NuG2)16 at the constant pulling speed of 500 nm sâˆ'1, we achieved the mechanical unfolding force of each domain in these proteins. Besides, we calculated the energy dissipation of NuG2, (NuG2)8 and (NuG2)16 by measuring the area enclosed by stretching and relaxation traces. Our results represent a key step towards engineering artificial polyproteins with controllable mechanical force and energy dissipation properties for force-buffering and energy dissipator applications. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This paper presents a study of closely spaced double tunnels in Taizhou, China. One is Xiabei Mountain No. 2 four-line super-span high-speed railway tunnel (HRT), and the other is Xiabei Mountain double-line large-span subway tunnel (ST). The excavation spans of HRT and ST are 26.3 and 14 m, respectively. The two tunnels are located at different levels, and their separating distance is 17.2 m. Due to the short construction period, the HRT excavation was completed earlier than ST. The structural design of the HRT, taking account of the disturbance by the ST construction, was analyzed by a numerical simulation. It was found that the "yielding principle" design was more feasible than the "resistance principle" design when considering the safety and durability of the HRT secondary lining. The mechanical responses of the HRT during ST construction were comprehensively monitored and analyzed, including the vault settlement, horizontal convergence, surrounding rock pressure, and the internal stress in shotcrete and steel arch. Results show that the longitudinal influence range of the ST construction on the HRT was approximately 0.6–1.1 times the ST outer diameter; the disturbance was mainly generated in the ST upper bench excavation; and the final axial force of the HRT shotcrete was approximately 9–16 times that of the steel arch, which indicated that the shotcrete was the main bearing structure. The safety status of the HRT was assessed based on the monitoring data, and the minimum safety factors of the HRT shotcrete and steel arch were 1.61 and 1.89, respectively. Parametric studies were performed to show how the lining stress of HRT was affected by the relative angle, pillar width, ST excavation method and excavation footage. Finally, the design and construction optimization were proposed according to the monitoring data and parameter analysis results. This study might provide practical reference for similar projects. [ABSTRACT FROM AUTHOR]

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering 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 mechanical response of CFRP laminates under low-velocity oblique impact was investigated using finite element simulation and experimental test in this paper. Based on the 3D Hashin failure criterion, bilinear cohesive constitutive model and progressive failure theory, a finite element model of CFRP laminate with hemispherical cylindrical impactor under low-velocity oblique impact was established, by using finite element simulation software ABAQUS. A clamp for multi-angle impact was designed and manufactured. A low-velocity oblique test platform was built based on the clamp. Several groups of experiments with different impact angles and impact energy were carried out. It was found that the damage morphology and energy absorption caused by normal impact and oblique impact is quite different. For normal impact, the main damage mode on the front of the laminate is indentation, while for oblique impact, the main damage mode on the front surface is scratch due to the sliding of the impactor on the laminate. The damage caused by normal impact on the back of the laminate is always more significant than that caused by oblique impact. The simulation results of the contact force and the residual velocity of impactor are compared with the experimental results, and the good agreement verifies the reliability of the simulation model. The mechanical response is studied by simulation, and it is found that the mechanism of normal impact is different from that of oblique impact. The contact force and residual kinetic energy of the impactor decrease with the increase of impact angle, while the contact time and the energy consumed by friction increase are the opposite. The energy absorbed by the laminate is not negatively related to the impact angle. [ABSTRACT FROM AUTHOR]

In practice, the reservoir granite will experience the coupling process of high temperature and water cooling shock during dry hot rock mining. The granite was heated and cooled at room temperature and water cooling respectively, and ultrasonic test, uniaxial compression test, XRD, scanning electron microscope and other tests were carried out to explore the impact of high temperature and cooling mode on the granite damage characteristics. It is found that high temperature leads to the increase of volume, decrease of mass, decrease of p-wave velocity, decrease of elastic modulus, and decrease of compressive strength of granite. The physical and mechanical properties of granite deteriorate rapidly at 500℃-700℃. In micro, high temperature leads to the formation of micro-cracks, and water cooling treatment promotes the cracking and propagation of micro-cracks. Macroscopic water-cooled granite has lower physical and mechanical properties and higher ductility and ductility. [ABSTRACT FROM AUTHOR]

An iron ore mine at Anhui Province of China is in the transition from open pit to underground mining. The closed open pit of this mine will be filled with mine waste for land reclamation. This is conducive to the sustainable development of the mine. However, filling the open pit may affect the exploitation of lower mineral resources. Therefore, the influence of the filling of the pit on the underground mining operation should be investigated. A numerical model is thus established to study the mechanical response of the pit and underground stope to the open pit filling. The strain–time evolution of backfill with binder content and stress–strain data of backfill with curing time are investigated and thus used to compare with the relevant outcomes predicted by the developed model. The comparison results can prove the validity and applicability of the developed model. The validated model is then applied to study the evolutions of stress and displacement of the pit and stope during the filling process. The simulation results indicate that stress concentration of the slope, pit bottom and underground stope evolves during the filling process. The displacement of the stope roof is affected by the horizontal distance between the stope and the pit bottom. Filling the open pit can reduce the maximum stress on the stope roof. The obtained results can be combined with the field monitoring data in the future, which will provide guidance for the better production arrangement of the open pit filling and underground stope mining. [ABSTRACT FROM AUTHOR]

A new Ti64-Fe-Co alloy was studied via a laser-material-deposition method. Associated with high growth restriction factors, β-eutectoid (Fe, Co) alloying minimizes anisotropy (due to the prior columnar β-grain growth) in the laseradditive -manufacturing (AM) built Ti-parts along with enhanced properties. Fe alloying for Ti64 via laser-AM results in superior strengthening with reduced ductility, where a good combination of strength and elongation properties can be achieved for a Ti-Fe-Co system. However, studies on Ti-Fe-Co-based systems via laser processing are limited. Co possesses a similar electronic property as Fe and the Ti-Fe system accompanies further solute addition. The effect of Co alloying the Ti64-Fe system was investigated in this study via a pre-placed laser-material-deposition method. A Ti64–5Fe-5Co alloy was formulated referring to CALPHAD simulations, along with a Ti64–10Fe composition. The new Ti-alloys were fabricated via both the laser-material-deposition and conventional vacuum arc melting routes, and the characteristics of the fabricated samples were examined. XRD analysis shows the evolution of the β-Ti phase with Fe and Co alloying, which agrees with the thermodynamic phase simulation results. The corresponding SEM micrographs depicted a β-phase dominant matrix with α-dendrites, and the solidification path was discussed. Considerable grain refinement was obtained for the laser-deposited alloys compared to the arc-melted ones, with an improved hardness value twice that of the commercial Ti64. A reduced stiffness for the laser-deposited Ti64–5Fe-5Co was observed from the load-vs-displacement characteristics, indicating matrix softening with Co alloying, which might benefit the elongation properties. The studied Ti-alloy shows a 30 % improvement in the dry-sliding wear characteristic with reduced fretting and abrasion compared to the commercial Ti64. The studied Ti-alloys were located in the theoretical d-electron space and new (Bo) ̅-(Md) ̅ vectors were introduced. Further studies on this would help in extending the applicability of laser-AM-built Ti-components. [Display omitted] • New Ti64-Fe-Co-based alloy designed and synthesized via laser-material deposition. • Phase evolution and microstructure with β-phase alloying were studied. • Observed matrix softening with Co-alloying might contribute to improved elongation. • The studied Ti-alloy showed improved hardness and dry-sliding wear resistance. • New Bo ̅ − Md ̅ vectors were introduced for the Ti-alloy system in the d-electron space. [ABSTRACT FROM AUTHOR]

(A) Schematic representation of PVA/SA fibrous matrix scaffolds reinforced with collagen (COL) or hyaluronic acid (HA) molecules. The cross-linking process illustrates the interactions between the functional groups of COL (inset I) or HA (inset II) with the matrix forming additional H-bonds. (B) Nanoindentation results show a significant stiffness enhancement in reinforced systems with high SA content. [Display omitted] • Collagen reinforcement yields stiff material with high nanohardness. • Hyaluronic acid reinforcement results in a softer material with increased modulus. • Reinforced systems have a protective effect on degradation and raised crystallinity. • H-bonds induced by collagen or hyaluronic acid increase scaffold swelling ratio. The increasing use of biomaterial scaffolds in tissue engineering applications demands a comprehensive understanding and precise control of their overall properties. This work analyzes the synergy of naturally occurring biological macromolecules on the swelling, and thermal and mechanical properties of ionically crosslinked polyvinyl alcohol (PVA)/sodium alginate (SA) fibrous scaffolds. The presence of collagen (COL) or hyaluronic acid (HA) contributed not only to increasing the hydrogen-bond density but also to induce the crystalline PVA phase formation. Consequently, the swelling, thermal degradation, elastic modulus, and nanohardness of the scaffolds were significantly enhanced. By considering COL and HA the relevance in diverse cellular processes and tissue functions, the PVA-scaffolds here introduced are promising materials by providing advanced multifunctionalities. [ABSTRACT FROM AUTHOR]

• A novel segment structure consisting of NC and UHPC composite. • The mechanical behavior of joints in NC-UHPC composite tunnel segments. • The NC-UHPC composite segments exhibit good toughness and ductility. • The NC-UHPC composite segments are more suitable for high axial loads. The performance of longitudinal joints in shield tunnel segments is crucial for ensuring structural stability and durability. This study presents an innovative segment structure combining normal concrete (NC) and ultra-high performance concrete (UHPC) (hereafter called NC-UHPC composite segment). Full-scale joint tests were conducted to analyze the mechanical response and failure characteristics of longitudinal joints in these segments. Compared to reinforced concrete (RC) segment joints, NC-UHPC composite segment joints exhibited a significant increase in initial cracking load by 197.93% under sagging moments and 435.3% under hogging moments. The ultimate load-bearing capacity increased by 55.71% and 67.10%, and the initial bending stiffness improved by 20.57% and 10.59% under sagging and hogging moments, respectively. Furthermore, NC-UHPC composite segment joints exhibited smaller crack distribution areas and fewer cracks, indicating superior crack resistance. No cracks or damage were observed at the NC-UHPC interface. Evaluation of joint toughness and ductility indices further highlighted the favorable performance of NC-UHPC composite segment joints. Finally, a refined numerical model was established to compare the deflection and bending stiffness of RC segment joints with NC-UHPC composite segment joints under varying axial forces. The findings suggest that NC-UHPC composite segments are more suitable for tunnel engineering with greater burial depth, higher water pressure, and larger axial forces. [ABSTRACT FROM AUTHOR]

Semi-rigid base asphalt pavements in Xinjiang suffer from various defects, particularly reflection cracks caused by extreme environmental conditions and dynamic vehicle loads. Adopting a flexible asphalt pavement is effective in inhibiting reflection cracks. In this study, asphalt pavement structures with three typical flexible bases were selected for numerical simulation under the coupled fields of a dynamic load and the actual environmental conditions in Xinjiang (high-, low-, and large-temperature-difference areas) using ANSYS. Heat transfer systems and heat radiation conditions were established based on an investigation of the temperature variations in typical high- and low-temperature areas. Simulations were conducted to establish the temperature field within the internal structure. A half-sine wave model was used to simulate the dynamic vehicle load, and a coupled field was established. The tensile strain, tensile stress, shear stress of the asphalt layer, shear stress of the graded gravel layer, vertical compressive strain at the top of the subgrade, and surface deflection were adopted to analyze the mechanical response under the coupled fields. According to the simulation results, the variations in tensile strain, shear stress of the asphalt layer, and shear stress of the graded gravel layer were 8.45 %-26.52 %, 38.38 %-52.96 %, and 12.66 %-20.65 %, respectively, in high-temperature areas. Increasing the asphalt layer thickness can significantly reduce the amplitude of the variation and peak value of the mechanical index of the pavement structure. At high temperature differences of 30 °C, 40 °C, and 50 °C, the maximum peak values of the asphalt layer tensile stress were 4–8 MPa. A summer climate can increase the shear stress in the asphalt layer by more than 30 %. These results support the application of flexible bases in asphalt pavements in complex external environments. • Coupling fields of temperature and dynamic load was established. • Actual environmental conditions was considered during numerical simulation. • Recommends of design for flexible base pavement structure in special environment in Xinjiang. [ABSTRACT FROM AUTHOR]

Micro electromechanical systems (MEMS) micro-pressure sensors have wide applications in consumer electronics, industrial monitoring, and biomedicine. However, as the next-generation portable and wearable devices bloom in recent years, existing design of pressure sensors faces great challenges to break the trade-off between the sensitivity and nonlinearity in the miniaturization process. Here, we report a sandwich-like Graphene/h-BN/Graphene-resistor heterostructure sensing element for micro-pressure detection. This novel design decouples pressure-to-strain translation process and strain-to-electrical signal sensing process by the insulation of bottom graphene structure layer and top graphene piezoresistive layer. We reveal the effects of the heterostructure dimensions, layer number and pretension on the mechanical performance utilizing finite element method (FEM) simulation, and propose the design principle of the piezoresistors and patterning strategy of the heterostructure. Remarkably, the heterostructure exhibits ultra-high sensitivity per unit area, outperforming state-of-art graphene and silicon-based sensors by up to five orders of magnitude, as well as a significant reduction of the nonlinearity. Our work shows tremendous potential of 2D material heterostructure as a promising platform to break the miniaturization limitation of ultrasensitive pressure sensors. [Display omitted] • Graphene/h-BN/Graphene van der Waals heterostructure was proposed for pressure sensing with footprint reduced to 6×6 μm2. • Sensitivity and linearity were improved compared to suspending graphene-based sensor by a factor of 28 and 16, respectively. • Area-normalized sensitivity of heterostructure was 2 to 5 orders of magnitude superior to silicon and graphene-based sensors. [ABSTRACT FROM AUTHOR]

The photopolymerization process is a high-precision and efficient technology to obtain solid polymers starting from a photosensible liquid resin made of monomer units. This technology is widely used in Additive Manufacturing (AM) to produce objects whose size can fall within the range 10 − 5 − 10 0 m. The outstanding potentialities of this technology can be harnessed to tailor the structure of a polymeric material by controlling how the light-induced polymerization process is performed, typically by operating on subsequent layers forming the final object. The present research illustrates the chemical-physics phenomena involved in the photopolymerization and presents a multi-physics framework and the related governing equations. Its implementation within a computational framework is developed and several simulations demonstrating the influence of the AM printing setup on the final microstructure of the obtained polymer are presented. It is shown that photopolymerization-based AM technology allows us to finely tune the mechanical properties distribution within the material domain, enabling the material's architecture to be tailored to the application of interest. • Multi-physics model of layered photopolymerization. • Mechanics of polymers obtained through photopolymerization. • Numerical implementation of the photopolymerization process. • Numerical simulations. • Layer-interface characterization. [ABSTRACT FROM AUTHOR]

Steel Strips Reinforced Thermoplastic Pipe (SSRTP) is a type of flexible pipeline that can be applied in offshore industries for extracting oil and gas. Due to the helical structure of SSRTP, the torsion may end up being the primary cause of failure. This study proposed a new theoretical approach that can predict the torque failure amount of SSRTPs precisely enough. A three-dimensional finite element model has been established and is validated by the experimental method. The characteristics that most significantly affect the torsional behaviour of pipe have been studied through a parametric analysis. Furthermore, some recommendations are made concerning the design of SSRTPs in practical engineering. • A theoretical approach is presented to determine the SSRTP response subjected to torsion. • Torsional behaviour under the negative direction of SSRTP has been investigated by FEM, theories and experiments. • The SSRTP model is divided into two sections to obtain the most vulnerable layer under torsion. • The width and winding angle of steel strips are effective parameters in the threshold locking points of the SSRTP. [ABSTRACT FROM AUTHOR]

• The effect of Cr and Ni on mechanical response and the microstructural evolution of nanocrystalline ferrite are explored using molecular dynamics. • Cr reduces dislocation density and leads to a transformation in mechanical properties during tensile and scratching. • Cr and Ni enhance the atomic binding strength with Fe and form lattice distortion. • Ni suppresses grain boundary slip and migration. • The formation of more nanoscale twins and twin-dislocation interactions can enhance strain-hardening ability during tensile. Microalloying plays a critical role in improving the mechanical properties of steel. To offer a better theoretical guide for experimental research at the atomic level, this paper investigated the synergistic mechanism of adding trace amounts of alloy Cr and Ni and the microstructure evolution of nanocrystalline ferrite during the mechanical response process. First-principles calculations were implemented to investigate electronic properties. Hybrid molecular dynamics and Monte Carlo simulations were employed to explore the deformation mechanism under uniaxial tension and scratching. Specifically, comprehensive differences between doped and pure nanocrystalline ferrites were explored regarding local stress-strain state, dislocation evolution, twin expansion, and grain boundary activity. The results show that Cr- and Ni-doped nanocrystalline ferrite has higher strength and better wear resistance. The potential mechanism is that the addition of Cr and Ni enhances the atomic bonding strength with Fe atoms, hinders the movement of dislocations caused by lattice distortion, and suppresses grain boundary slip and migration, thereby improving the resistance to plastic deformation and grain boundary stability. Theoretical calculations based on microstructure indicate that compared to solid solution strengthening, Ni-induced grain boundary strengthening plays a dominant role in improving yield strength. Under large deformation, the trend of mechanical response is reversed. The suppression of dislocation motion by Cr reduces the dislocation density and dislocation entanglement, resulting in flow stress and local scratch force being smaller than that of pure samples. However, the formation of more nanoscale twins and twin-dislocation interactions enhances strain-hardening ability during tensile. Finer nanostructured subgrains are formed under scratching. These results provide valuable insights into the understanding of the strengthening mechanism and plastic deformation mechanism of Cr-Ni system low alloy steel under dynamic loading. [Display omitted] [ABSTRACT FROM AUTHOR]

Simulating the evolution of microstructures and the mechanical response of alloys with cubic and hcp structures is crucial for the industrial manufacturing of key alloy components. In this work, a modified Voce (ME-Voce) model is proposed, based on the extended Voce hardening model, to depict the variations of hardening rate with cumulative shear strain. Also, an orientation-dependent weight that describes the neighboring grain-induced 'drag' effect is evaluated. These improvements are numerically implemented in a standard viscoplastic self-consistent (VPSC) model. The ME-Voce parameters are determined through multi-parameter optimization using Matlab software. The influences of grain shape and neighboring grains on the hot deformation behavior of alloys are investigated. The proposed ME-Voce model is validated through hot compression experiments of alloys with cubic and hcp structures. The results show the VPSC embedded in the ME-Voce can reasonably predict the mechanical response under different deformation conditions. This enhances the predictive capability of the VPSC model and provides more options for crystal plasticity simulation of alloys with different crystal structures. • A modified Voce model is proposed to depict the variations of hardening rate with cumulative shear strain. • An orientation-dependent weight describing neighboring grain-induced 'drag' effect is evaluated. • Viscoplastic self-consistent model including ME-Voce can reasonably predict the mechanical response of alloys. • More choices for crystal plasticity simulation of alloys with different crystal structures are provided. [ABSTRACT FROM AUTHOR]

This paper reports a flexible mechanical sensor developed by combining an opal photonic crystal and a flexible medium through UV curing technology. Under the action of external force, the deformation of the flexible medium causes the change of the photonic crystal lattice constant, which leads to the displacement of the reflection peaks, thus realizing the detection of the deformation of the film. The flexible medium is mixed by photoinitiators and polymer monomers, and its mechanical properties are directly related to the mass fraction of photoinitiators and polymer monomers. The results show that the film can reach a maximum strain of about 180% when the mass fraction of photoinitiator is 3% and the volume ratio of the polymer functional monomers is 8:2. In addition, for the responsiveness test of the sensor under tensile, the results show that at 0%, 26%, and 78% of tensile strain, its structural color is blue-shifted sequentially, and its spectral peaks are 668 nm, 535 nm, and 488 nm, respectively. Finally, the sensor is applied to the detection of acoustic waves in air, and it is found that its spectral response peaks can be obtained for acoustic waves of different frequencies (250–650 Hz), and a spectral peak at 500 Hz. This flexible photon sensor has the potential to match the acoustic resistance of water. It will greatly expand the response research of ocean exploration in the low frequency range. [Display omitted] [ABSTRACT FROM AUTHOR]

To investigate the influence of bolt pre-tightening force and hole-bolt spacing on the mechanical responses and failure characteristics of rock-like materials with hole-bolt composite structures, a comprehensive set of physical tests was carried out. The findings suggest that enhancing the pre-tightening force improves the peak stress and elastic modulus of the material. However, these properties initially increase and then diminish with widening hole-bolt spacing. An increase in pre-tightening force results in more fractures around the hole, altering the material's failure mode from tensile-shear to purely tensile. Additionally, as the hole-bolt spacing expands, the tensile crack positioned above the hole progressively shifts away from the bolt, leading to a transition in failure mode from tensile to tensile-shear. Field tests confirm that the bolt force proximate to the pressure relief hole remains significantly greater than that at a distance, establishing hole-bolt spacing as a critical factor in anchorage stability. • The mechanical response and failure behavior of hole-anchor composite rock-like materials was investigated. • The physical test considers the pre-tightening force and hole-bolt spacing on the influence of the rock-like material. • The failure process of the rock-like material are successfully captured by the Digital Speckle Correlation Method (DSCM). • The bolt force is influenced by the distance from the pressure relief in the physical test and verified through the field test. [ABSTRACT FROM AUTHOR]

The degradation of critical current due to mechanical deformation in a high field has a profound impact on the performance of high-temperature superconducting (HTS) structures. The multi-layer conductor on round core (CORC) cable is a widely-applied HTS structure in engineering. Due to the complexity of the multi-layer CORC cable, the contact between the tapes should be considered when simulating the mechanical behavior in high field. In this paper, 3D electromagnetic and mechanical models were developed to investigate the mechanical behavior of the multi-layer CORC cable. Under the same electromagnetic force, the comparisons of mechanical models of a 5-layer CORC cable with different contact methods are presented. Subsequently, the effects of the loading path of the external magnetic field and transport current, the bending geometry of the CORC cable, the winding direction of the HTS tape in the CORC cable, and the shielding current on the mechanical behavior are discussed, respectively. The numerical results are useful for the design and operation of CORC cable in high field. [ABSTRACT FROM AUTHOR]

Rock masses that undergo a long and complex geological tectonic process contain widely distributed parallel and intersecting flaws. These two types of flaws have different inclinations with the rock layer, resulting in a significant deterioration of the mechanical properties of the rock mass and complex fracture evolution characteristics. However, the effects of flaw inclination and the coupling effect between the two types of flaws on the dynamic response characteristics of rock masses are still unclear. In this paper, both qualitative and quantitative analysis methods are adopted to systematically analyze the influence of flaw inclination on the dynamic properties and fracture evolution mechanisms of rock masses containing both parallel and intersecting flaws via a modified split Hopkinson pressure bar (SHPB) apparatus, a high-speed camera, and digital image correlation (DIC) technology. The test results show that the peak stress and peak strain decrease initially and then increase with increasing flaw inclination from 0° to 90°. The origin of specimen failure and the proportion of energy are dominated by the flaw inclination. Furthermore, flaw tips are prone to strain concentration, which promotes and guides the crack propagation. The major cracks in flawed specimens always occur along flaws, and their failure modes can be classified into three categories: tensile failure along flaws, tensile‒shear composite failure along flaws, and tensile failure perpendicular to flaws. Additionally, fractal feature analyses indicate that the degree of fragmentation of the flawed specimens tends to increase and then decrease as the flaw inclination increases from 0° to 90°. [ABSTRACT FROM AUTHOR]

Polyether ether ketone (PEEK) has replaced some parts in downhole applications in the oil and gas industry, demonstrating a huge potential to eliminate the corrosion of metallic parts, especially those that are employed in acidic atmospheres and high temperatures, such as liners, impeller, and sealing applications. However, the performance of PEEK in real downhole conditions remains unknown. In this study, we therefore investigated the evolution of the microstructural, chemical, and mechanical properties of PEEK subjected to hydrochloric acid (HCl), which is the main acid used in downhole applications, at high temperatures. PEEK films with thicknesses of 250, 125, and 50 μ m , were saturated in HCl at 100 °C. Moreover, the hardness, elastic modulus, yield, and ultimate strength for the samples with a thickness of 50 μ m increased owing to the formation of new crystallites and enhanced chain mobility inside the PEEK microstructure. However, the changes in the mechanical response of the thicker samples were insignificant owing to the difficulty of HCl diffusion in their subsurface layers, especially with the increased crystallinity of the surface layer upon exposure to acids. • PEEK aged in hydrochloric acid at 100 °C showed notable changes based on thickness. • Aging increased crystallinity in PEEK film by 4%, indicating crystallization. • Aging increases the strength and hardness, while reducing the strain. • Aging of PEEK in HCL is a surface process, where the diffusion to sublayer is minimum. [ABSTRACT FROM AUTHOR]

[Display omitted] • At a same depth in concrete prism, the moisture content and sulfate concentration are higher at the diagonal of the prism. • There is no clear demarcation between ion convection and diffusion zones in concrete prism under dry-wet cycles. • The longer the wetting time in one dry-wet cycle, the deeper the spalling of concrete prism caused by sulfate attack. External sulfate attack (ESA) coupled with wetting–drying alternation poses a significant threat to the concrete durability, while there are few models to simulate the above ESA behavior. In this paper, a simplified transport-mechanical model is proposed to numerically analyze the deterioration of concrete prism under ESA and dry-wet cycles. Firstly, a transport model of sulfate ion in concrete prism is established by considering the behaviors of ion diffusion, convection and chemical reaction, and numerically solved by the finite difference method. Secondly, the crystallization pressure of sulfate products in porous system is analyzed to calculate the equivalent expansion force. Then, the expansion strain and its-induced damage are calculated, and the criterion of boundary movement is further proposed. On the basis of model validation, a numerical simulation is performed to analyze the transport-mechanical response in concrete prism under ESA and dry-wet cycles. The results show that, there is no clear demarcation between the convection and diffusion zones in the prism. The spatial–temporal evolution of ESA-induced damage is similar to that of ion concentration. The longer the wetting time in one dry-wet cycles, the deeper the spalling of concrete prism caused by ESA. [ABSTRACT FROM AUTHOR]

Aluminium alloys designed for additive manufacturing with Zr addition exhibit heterogeneous microstructures from the grain scale down to the atomic scale. Bimodal grain structures with submicron equiaxed grains near the melt pool boundaries and columnar grains at the melt pool interiors are observed. The regions consisting of submicron grains are interconnected in 3D. The tensile response of these alloys often shows the presence of a stress plateau or a yield drop phenomenon near the yield strength but the underlying mechanisms still need to be clarified. Herein we investigate the tensile response of a new Al-4Mn-3Ni-2Cu-1Zr alloy in various conditions: after a stress relief (SR=300 °C/4 h) as well as after ageing at 400 °C for 1 h, 4 h (peak-aged) and 96 h (overaged). Based on the plot of the work hardening rate vs true stress, we identify specific characteristics allowing to appreciate the evolution of the elastoplastic transition depending on the heat treatment. The presence of microyielding and a stress plateau near the macroscopic yield strength are evidenced. Microscale DIC based on the local contrast provided by the microstructure decorated by a high fraction of intermetallic particles turns out to be the relevant scale to clarify the mechanisms involved in the elastoplastic transition. Microyielding is related to the regions near the melt pool boundaries and to the columnar grains. The latter yields at lower stress in comparison with the submicron grains due to a reduced contribution of grain boundary strengthening. The stress plateau is attributed to the low work-hardening capacity of the submicron grains. [Display omitted] [ABSTRACT FROM AUTHOR]

The fractured zone poses a significant risk to construction safety and structure durability in tunnel engineering. However, the effect of excavation methods has not been thoroughly investigated in previous studies. This paper presents a series of 1:30 scale 3D model tests on fault tunnels under the coupling effect of different fault dip angles and construction steps. We measured and analyzed the rock mass deformation and lining structure stress to explore the influence of tunnel excavation by the CD method. The model test results were verified by numerical simulation using the prototype tunnel parameters. Our results show that steeper fault dips correspond to greater radial pressure of the surrounding rock, and pressure in both haunt positions changes more significantly than that in the vault position, while pressure in the side-wall position changes only slightly. Additionally, considerable deformation can be observed in the vault and both haunt positions, with a rock mass relaxation range of less than 1.0 D. For the lining structure stress of each point in the second excavation cycle, larger lining stress is measured in the case of a fault dip of 75° than that in cases when the fault dip equals 45° and 60°, respectively. The biggest stress is observed in the side-wall position after the mid-partition is mantled to form a closed-loop lining structure. Overall, our findings provide valuable insights into the construction response of tunnels through faults and highlight the importance of considering excavation methods in tunnel engineering.

MEMS safety and arming device (SAD) with merits of small size and easy integration is one of the most promising candidates for the fuze to realize miniaturization, integration and intelligence. In this paper, a novel inertia-driven MEMS SAD with three independent safety features is proposed. The SAD placed perpendicular to the projectile axis is beneficial to reduce the size and improve the detonation energy transfer efficiency. The dynamic finite element simulations are carried out to study the mechanical responses of the device under dual-environment inertial loads. The response behaviors of the setback and centrifugal safety features and interrupter under different loads are elucidated and discussed. A series of experiments are performed to verify the simulation analysis results and investigate the safety and arming performances. The results indicate that the proposed MEMS SAD with small size and compact structure has successfully achieved safety and arming performances. The experimental results are in good agreement with the simulated analysis results. [ABSTRACT FROM AUTHOR]

In order to analyze the reasonable level and use of high-modulus asphalt concrete in the full-thick asphalt pavement, based on the typical all-thick asphalt pavement structure of Shandong Province. The numerical model of full, thickness asphalt pavement structure was constructed, and high-modulus asphalt concrete was placed in the lower layer, the botlem base layer, the base layer, the base layer + bottom base layer, the lower layer + bottem base layer and without high modulus asphalt concrete, the differences in mechanical response indicators under various working conditions was analyzes. Taking mechanical response improvement rate to determine the rational layer of high modulus asphalt concrete, and verifie the orthogonal test. The results show that the mechanical response has improved under the fact that the operating conditions is increased, and the high modulus asphalt concrete settings can significantly improve the structural performance of all, thick asphalt pavement, and it is recommended to be set in the following layers and the base layer is orthogonal experimental analysis, and the high modulus asphalt concrete is reasonable in the lower layer and the base layer. [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. [ABSTRACT FROM AUTHOR]

The formulation of an innovative concrete that meets the requirements of a self-compacting concrete (SCC), with acceptable performance in terms of rheology in the fresh state; good fluidity, ease of placing, without segregation as well as good mechanical strength and durability at hardened state has become of great research interest for the last decades. Numerous studies have shown the favorable effects of limestone fillers on the SCC properties. This study aims at investigating the effect of inert mineral addition of limestone fillers with dosages of 10% and 20% grinded to different fine nesses 2000, 3000 and 4000 cm²/g on the physico-mechanical properties of a fresh self-placing concrete using slump, the L-box and the sieve stability tests. Also, the means of destructive and non-destructive tests (NDT) methods to the assessment of the mechanical performances of SCC at hardened state were used. The use of experiment factorial design method allows us to have behavior laws to predict the mechanical strength response when combined with (NDT) according to a numerical model in such study. Hence, a numerical modeling of mechanical response could be derived by such statistical analysis in regards to the effects of factors and their interaction. The results obtained showed that the incorporation of limestone filler in the composition of the SCC improves the fluidity with limited segregation, as well as the good mechanical performances (resistance to compression and flexion). The numerical modeling of the predicted compressive strength response, in particular at the age of 28 days, is judged to be with an acceptable determined coefficient R² equal to 0.994. [ABSTRACT FROM AUTHOR]

Reflective cracks in asphalt pavement are major distresses in semi-rigid pavement. To date, grouting and jointing filling are commonly used to solve this problem. However, the grouting materials cannot be filled with cracks that have not propagated to the surface of base. Thus, these measures are limited to reducing the potential cracks in the base. This paper presents a comprehensive treatment measure of base regeneration by preset cracking and grouting (BRPCG) to repair the semi-rigid pavement with severe reflective cracks. The effect of BRPCG on the crack resistance of pavement was investigated by a linear elastic model. The dynamic load and the dynamic load–temperature coupling programs were designed to obtain the mechanical responses of pavement. Furthermore, mechanical indexes based on fatigue and yield failures of pavement materials and crack coefficients were proposed to evaluate the crack resistance and safety of pavement. The results showed that the temperature difference and aging of the original pavement are two factors that should be considered when simulating the pavement structure in service. The temperature of the coupling effect has a greater influence on the tensile stress of the structure layer compared to the dynamic load. The overload conditions only increased the value of the mechanical indexes without changing the variation trend of these indexes. [ABSTRACT FROM AUTHOR]