Strong Deformation Research Articles

Stress Drops of Intermediate‐Depth and Deep Earthquakes in the Tonga Slab

AbstractMultiple physical mechanisms have been proposed to explain the cause of intermediate‐depth and deep earthquakes, but they are still under debate. Source parameters such as stress drop, have the potential to provide insight into their physical mechanisms. We develop a modified spectral decomposition method to analyze 1‐year seismic data from temporary land‐based and ocean bottom seismographs in a complex subduction zone. By applying this method to investigate 1,083 intermediate‐depth and deep earthquakes in the Tonga slab, we successfully resolve the source spectra and stress drops of 743 MW 2.6–6.0 earthquakes. Although the absolute stress drops are subject to the choices of source model parameters, the relative stress drops are more reliably resolved. The median stress drop of Tonga earthquakes does not change with respect to magnitude but decreases with depth by 2–3 times in two separate depth ranges of 70–250 and 400–600 km, corresponding to intermediate‐depth and deep earthquakes, respectively. The median stress drops show spatial variations, with two high‐stress‐drop (five times higher than the ambient value) regions, coinciding with strong local deformation where the Tonga slab bends or tears. In the Tonga double seismic zone at 120–300 km depths, the median stress drop appears smaller in the lower plane than in the upper plane, suggesting a slower rupture velocity or a higher fluid content in the lower‐plane region. Our results suggest that intermediate‐depth and deep earthquakes in the Tonga slab generally follow the earthquake self‐similar model and favor the fluid‐related embrittlement hypothesis for both groups of earthquakes.

Investigation of the physical and mechanical properties of the heterogeneous structure of the Mn - Cu alloy system

The era of automation has come, a new type of machine production that frees people from work in production and automates technological processes, mechanisms and machine control. Automation not only increases the efficiency of any production, but also opens the way to achieve the best results. This article deals with the physical and mechanical properties of the heterogeneous structure of the mortar system. Regardless of whether technological processes are automated, mechanized, or group processing is used, automated site tuning activities remain labor-intensive and performed using manual labor. Considering the types of electrical technical materials, their properties, we reveal their advantages and use them in production facilities. Non-ferrous metals are very important in technology. Because there is a demand for them based on their physical and mechanical properties. Scientific research was conducted at the Department of Physics of the International Kazakh-Turkish University named after Khoja Ahmet Yasawi as a base. The method of heating, melting, processing, evaluation and analysis of alloys was used as a scientific method. Experimental studies were carried out on copper alloys with 45-85% manganese, 50 and 60% alloys doped with various elements and their combination in concentrations up to 10. Repeated measurements were made to obtain high accuracy. Structural and phase changes in metallic materials during extreme external effects (strong plastic deformation, high pressure, temperature, radiation, aggressive environment) were studied. We studied structural and phase changes in metallic materials during extreme external influences (strong plastic deformation, high pressure, temperature, radiation, aggressive environment).

Restricted lithospheric extrusion in the SE Tibetan Plateau: Evidence from anisotropic Rayleigh-wave tomography

Constraining variations of lithospheric structure and deformation across southeastern Tibet and the surrounding region are crucial for understanding the lateral growth of the plateau. Using data from two dense seismic arrays in the SE Tibetan Plateau, we obtained fine-scale Rayleigh-wave phase velocity maps by Eikonal tomography, and further inverted for 3-D shear wave velocity and azimuthal anisotropy of the crust and upper mantle. High velocities and weak lithospheric anisotropy are revealed under Dianzhong Block (DZB), where is covered by the relics of the Emeishan Large Igneous Province, while strong anisotropy is imaged around. We propose that the DZB strengthened by the paleo igneous activity plays an essential role in the evolution along the southeastern plateau margin. On the one hand, the DZB obstructs the migration of plateau material to the southeast. On the other hand, strong deformation is localized along the DZB margins, while the stress due to the plate expansion is transferred further to the Xiaojiang fault, which induced significant deformation within the Yangtze Craton. Furthermore, the lithosphere of DZB deflects the mantle flow driven by the eastward Indian subduction under the northern Indochina block.

Robust cholesteric liquid crystal elastomer fibres for mechanochromic textiles

Mechanically responsive textiles have transformative potential in many areas from fashion to healthcare. Cholesteric liquid crystal elastomers have strong mechanochromic responses that offer attractive opportunities for such applications. Nonetheless, making liquid crystalline elastomer fibres suitable for textiles is challenging since the Plateau–Rayleigh instability tends to break up precursor solutions into droplets. Here, we report a simple approach that balances the viscoelastic properties of the precursor solution to avoid this outcome and achieve long and mechanically robust cholesteric liquid crystal elastomer filaments. These filaments have fast, progressive and reversible mechanochromic responses, from red to blue (wavelength shift of 155 nm), when stretched up to 200%. Moreover, the fibres can be sewed into garments and withstand repeated stretching and regular machine washing. This approach and resulting fibres may be useful for applications in wearable technology and other areas benefiting from autonomous strain sensing or detection of critically strong deformations.

Gradient of mechanical properties in polymer nanocomposites: From atomistic scale to the strain gradient effective continuum

It is well known that glassy polymer nanocomposites (PNC) exhibit heterogeneous mechanical properties, with a distinct polymer/nanoparticle (NP) interfacial region. The interphase rigidity in particular can significantly influence the overall mechanical response of glassy PNCs. Continuum theories typically describe the mechanical behavior of the interphase such to depend only on the deformation and, thus, they discard the strong internal deformation gradients within the interphase, that are necessary for enriched continuum models of the PNC’s. Here we formulate a higher-gradient elasticity constitutive law for the polymer/NP interphase region through a systematic micro–meso–macro coupling, using data from atomistic molecular dynamics (MD) simulations. From a physical standpoint, we show that in order to accurately consider the polymer/NP interphase is necessary to describe it as a strain gradient material, whereas the bulk material may still behave as a Cauchy material, experiencing much lower strain gradient effects, compared to the polymer/NP interphase. Using atomistic MD simulations, the polymer/NP interphase thickness in PNCs is examined by probing the density profile distribution at equilibrium. By upscaling the molecular response within the interphase towards a continuum model, a strain gradient effective model for the interphase emerges, whereby the hyperstress tensor and the conjugate strain gradient, together with the stress and strain, are computed for each atom using the MD simulations. In a further upscaling step, a continuum-based homogenization scheme based on the unfolding method is elaborated for the identification of the strain-gradient elastic moduli of polymer composite materials, according to which the interphase obeys a second-gradient linear elastic constitutive law, with an inner reinforcement and an outer surrounding matrix obeying a first-gradient elasticity model.

Effect of Multi-Components Strong Motion Duration on Seismic Performance of High CFRDs Based on Fragility Analysis

ABSTRACT This paper investigates the influence of multi-components strong motion duration on seismic performance of high concrete-faced rockfill dams (CFRDs) by fragility analysis based on the method of incremental dynamic analysis (IDA). The contributions of all compositions of earthquake excitations are considered by the definition of integrated duration based on the concept of significant duration. The nonlinear finite element model of a 2D 200-m-high CFRD is established as a case study and the vertical and horizontal displacements are selected as damage measures. Fragility curves and probabilities of two sets of 23 and 25 spectrally equivalent as-recorded bi-directional long-duration and short-duration motions are determined under different failure grades and intensities. The results show that the duration of vertical component has a certain effect on correction between strong motion duration and deformation of the dam and fragility analysis indicates that the ground motions with long duration can make more risk of failure of high CFRDs than short duration motions. Therefore, the seismic performance of high CFRDs will be reformed by taking the effect of ground motion duration into seismic design and risk assessment consideration.

Rapidly reversible discoloration of liquid metal by contact or separation

Silver-white liquid metals (LMs), such as gallium (Ga), eutectic gallium-indium (EGaIn) and gallium-indium-tin (GaInSn) are becoming increasingly important functional materials in macroscopic bionic robots for their strong room temperature deformation capacities. However, their shiny color makes them particularly easy to be detected and “terminated”. Therefore, how to naturally blend in with the surroundings and possess the contact discoloration capacities like the cyborg T-1000 terminator secretly crawling out of the chessboard floor in the movie, is what sci-fi fans are striving to pursue. Herein, we show a rapidly reversible silver-white to dark brown discoloration of LM GaInSn induced merely by being touched by or separated from a piece of rough surface graphite paper. Enhanced charge transfer by rough graphite paper constitutes the main reason for the contact induced discolorations. This work should suggest an exciting way for camouflage, light harvest skin materials on LM smart bionic soft robots.

Tracking the multi-stage metamorphism and exhumation history of felsic gneisses in the South Altyn ultra-high pressure metamorphic belt, Western China

Felsic gneisses are usually the dominant rock types in most high-pressure (HP) and ultrahigh-pressure (UHP) terranes, although their peak metamorphic conditions and complete P–T paths are rarely known. This lack of knowledge is attributed to the high variance of mineral assemblages at HP/UHP conditions of the felsic gneisses, or to the effects of retrograde-related overprinting. Thus, it is difficult to distinguish whether felsic gneisses underwent HP/UHP metamorphism. In this paper, we focus on the felsic gneiss that has been previously documented as having formed under HP granulite-facies metamorphism with peak P–T of > 1.15 GPa and > 860 °C from the Danshuiquan locality in the South Altyn HP–UHP belt. The Danshuiquan felsic gneiss is strongly deformed and is spatially associated with weakly deformed garnet-rich felsic gneiss. On the basis of detailed microstructure observations on mineral assemblages and phase equilibria modelling, three stages of metamorphic evolution for the weakly deformed garnet-rich felsic gneiss are identified. The first stage is represented by garnet cores, revealing a prograde P–T path from 1.5 GPa/750 °C to 2.1 GPa/900 °C. The second stage is characterized by garnet mantles with multiphase inclusions, defining HP eclogite-facies metamorphic conditions of 2.2–2.6 GPa/950–1100 °C. The third stage is represented by the composition of garnet rims, biotite, and plagioclase, suggesting an HP granulite to amphibolite facies decompression cooling process to 1.1–1.3 GPa/710–770 °C. In contrast, the strongly deformed felsic gneiss just records a deformation-related decompression process from 1.1 to 1.2 GPa/750–760 °C to 0.87–0.98 GPa/760–770 °C, and finally to 0.83 GPa/740 °C. Zircon U–Pb dating yields c. 920 Ma protolith ages, c. 500 Ma eclogite-facies ages, and c. 480 Ma granulite to amphibolite facies retrograde ages for the Danshuiquan felsic gneisses. Our results show that the Danshuiquan felsic gneisses underwent a similar metamorphic evolution process to that of Yinggelisayi HP–UHP rocks in the eastern segment of the South Altyn Tagh. Most HP mineralogical records tend to be eliminated by the strong deformation at crustal depths (∼30 km), meaning that the peak metamorphic conditions of the studied felsic rocks in UHP metamorphic terranes are previously underestimated.

Simulation analysis of flank wear and tool life prediction for cutting superalloy under high-pressure cooling

The effect of flank wear on the cutting process of PCBN tool machining GH4169 superalloy under high-pressure cooling conditions was studied in this article. First of all, the cutting models of different flank wear under conventional cooling and coolant pressure of 50 bar were established by the Third Wave AdvantEdge. Secondly, under the same wear state, the author compared the simulation results of high-pressure cooling with that of conventional cooling. Simultaneously, the influence of flank wear width(VB) on cutting force, the temperature of the machining zone, and surface residual stress during coolant pressure of 50 bar was discussed. Finally, the PCBN tool life forecasting model was established by a method of the GA-BP neural network, and then the generalization ability of the forecasting model was evaluated by 6-fold cross-validation method. The results show that high-pressure cooling cutting effectively grows down the cutting force and temperature generated during the cutting process, and with the rise of flank wear width(VB), the cutting force, the temperature of the machining zone, and residual stress values show an increasing trend. The main reason is that the aggravated flank wear results in strong extrusion friction and plastic deformation in the contact area between the tool and the workpiece, which has different effects on the force-thermal characteristics.

Bio‐Inspired Wrinkled Photonic Elastomer with Superior Controllable and Mechanically Stable Structure for Multi‐Mode Color Display

AbstractColor is an excellent carrier of information between organisms. Photonic elastomers that convert abstract mechanical information into intuitive color information have shown great potential in various application fields. However, angular correlation of structural colors and monotonous color conversion mode affect the accuracy of material information reading and the applicability in diverse application scenarios. Here, inspired by a kind of bright blue spider‐ Poecilotheria metallica, a new wrinkled photonic elastomer structure is reported. Through wrinkling stretchable 1D photonic crystals (1DPCs), photonic elastomers with both one‐directional and omni‐directional angle‐independent brilliant structural colors are realized. It is worth noting that with the hybrid 1DPC and polydimethylsiloxane substrate support, the wrinkled photonic structure and structural color remain stable after 1000 strain cycles, and mechanochromic sensitivity can reach 3.25 nm/%, indicating strong structural stability and sensitive deformation performance under stress. More importantly, by comprehensively manipulating micro‐wrinkle structure and lattice spacing of the photonic films, the structural color can achieve delayed discoloration and invisible‐visible reversible switching performance only through a single strain direction. The proposed wrinkled photonic elastomers have a broad application value in the fields of visual strain sensing, wearable devices, and information encryption. Furthermore, it provides a new strategy for color regulation of photonic materials.

Orogenic belt resulting from ocean-continent collision

Abstract Orogenic belts have been thought to form through plate convergence, involving subduction of oceanic lithosphere at continental margins (accretionary orogens), which may ultimately lead to ocean closure and continent-continent collision (collisional orogens). Intraplate orogens away from plate margins have been known, but the mechanisms controlling their evolution are poorly understood. The South China craton, including the Yangtze and Cathaysia blocks, underwent a Paleozoic orogenesis that formed a >500-km-wide orogenic belt with widespread granitoids that are unconformably overlain by Devonian cover sequences. The pre-Devonian basement rocks were subjected to strong deformation and greenschist-to amphibolite-facies metamorphism at 460–400 Ma. Paleozoic magmatism was characterized by voluminous crustally derived Silurian granitoids associated with incorporation of ancient crustal materials at 450–440 Ma and addition of juvenile mantle-derived melts at 420–410 Ma. Based on the absence of arc-like magmatism and the existence of ophiolites in the West Cathaysia terrane, geochemical evidence that oceanic crust existed beneath the East Cathaysia terrane, and geophysical evidence of contrasting lithospheres on both sides and two discrete slabs beneath their fault boundary, we propose that this Paleozoic orogenic belt was formed by collision between the two terranes that was driven by far-field forces during the assembly of Gondwana, and the East Cathaysia terrane represents oceanic lithosphere that was overthrusted by the continental crustal materials of the West Cathaysia terrane. Numerical modeling shows that this type of collision can explain the dynamics of the Paleozoic orogenesis in the South China craton and may be a mechanism for some orogens in which subduction-related igneous and metamorphic rocks are lacking.

Numerical simulation of strain localization through an integrated Cosserat continuum theory and strong discontinuity approach

In this paper, we propose a new numerical approach abbreviated as Cos-SDA for analyzing strain localization problems of geomaterials. The Cos-SDA is achieved by implanting the strong discontinuity approach (SDA) into the computational framework of the Cosserat continuum finite element approach (Cos-FEA). Through two numerical examples of plane strain compression test and slope stability, it is demonstrated that the Cos-SDA model can effectively simulate the entire progressive failure process of geomaterials from weak discontinuity to strong discontinuity. Cos-SDA can effectively alleviate the influence of mesh distortion in shear zone, and the numerical solution can still maintain convergence even under large deformation. Cos-FEA and Cos-SDA have much stiffer mechanical response than SDA-FEA since an internal length scale is introduced into the governing equations. In contrast, the SDA-FEA shows more conservative as the unmature bifurcation occurs and weak discontinuous stage is ignored in the numerical simulation, while Cos-FEA numerical results show an over-stiff mechanical response in the stage of post failure. Cos-SDA inherits the advantages of both SDA-FEA and Cos-FEA and neutralizes their mechanical responses, so it is more reasonable in simulating the progressive failure process from weak discontinuity deformation (strain localization) to strong discontinuity deformation (slip) occurring in geomaerials.

Collisions between CO, CO_2, H_2O and Ar ice nanoparticles compared by molecular dynamics simulation

Molecular dynamics simulations are used to study collisions between amorphous ice nanoparticles consisting of CO, CO_2, Ar and H_2O. The collisions are always sticking for the nanoparticle size (radius of 20 nm) considered. At higher collision velocities, the merged clusters show strong plastic deformation and material mixing in the collision zone. Collision-induced heating influences the collision outcome. Partial melting of the merged cluster in the collision zone contributes to energy dissipation and deformation. Considerable differences exist—even at comparable collision conditions—between the ices studied here. The number of ejecta emitted during the collision follows the trend in triple-point temperatures and increases exponentially with the NP temperature.

Chemical, microstructure, and mechanical property of TiAl alloys produced by high-power direct laser deposition

• A gradient TiAl specimen whose chemical composition varied greatly along the building direction was fabricated by high-power direct laser deposition. • The microstructure transforms from basket-weave microstructure into acicular martensite microstructure as the height increases, and the mechanical properties also vary greatly when the height changes. • By characterizing the deformation behaviors under the indentations, it is concluded that the phase constitution is responsible for the variation of the mechanical properties. Additive manufactured metals sometimes exhibit extraordinary microstructures and mechanical properties due to the particular processes. In this paper, we focus on a novel gradient TiAl alloys fabricated by high-power direct laser deposition, whose chemical composition, microstructure, and mechanical property vary along the building direction. The results indicate that Al concentration dramatically decreases from 39.5 at.% to 30.1 at.% as the height increases from the bottom to the top. Meanwhile, microstructural characterization indicates that the specimen appears basket-weave microstructure at the bottom, then the α 2 and γ phase gradually decrease, and eventually it transforms into acicular martensite microstructure in the top region. The indentation analysis shows that the associated hardness increases as the height increases, while the plasticity reaches a minimum value in the middle region. The increasing amount of β o (ω) is considered to be responsible for the increasing hardness because of the strong precipitation strengthening effect. The high plasticity in the bottom and top regions results from the strong deformation behaviors of the γ and β o phases.

Anomalous Radial Anisotropy and Its Implications for Upper Mantle Dynamics Beneath South China From Multimode Surface Wave Tomography

AbstractThe strength of radial anisotropy can effectively reveal vertical or horizontal material flow, which may provide significant dynamic implications. The South China Block (SCB) is a classic laboratory to study strong deformation under compression from the surroundings. We construct a radially anisotropic 3‐D shear‐wave model of the entire SCB using multimode surface wave tomography with a lateral resolution of 2.0°. Distinctive structural contrasts are revealed in the S‐wave velocity anomalies in the Cathaysia Block and the Yangtze Craton. In the Cathaysia Block, a low‐velocity anomaly becomes evident with increasing depth, particularly in the VSH model. The Yangtze Craton is, however, characterized by a high‐velocity anomaly, especially in the Sichuan Basin, where the high‐velocity feature can extend down to a depth of 300 km. Interestingly, an abrupt change in radial anisotropy is observed beneath the Sichuan Basin, with positive radial anisotropy (faster VSH) in the uppermost mantle and negative radial anisotropy (faster VSV) at depths from 80 to 250 km. The lower negative anisotropic layer may reflect the directional arrangement of constituent materials caused by eastward compression and erosion of mantle flow under the Tibetan Plateau. In addition, remarkable negative radial anisotropy is found in the asthenosphere beneath Hainan Island and its surroundings. The features beneath Hainan Island and its surroundings may be related to the Hainan mantle plume in the Cenozoic.

Deformable 3D-2D image registration and analysis of global spinal alignment in long-length intraoperative spine imaging.

Spinal deformation during surgical intervention (caused by patient positioning and/or the correction of malalignment) confounds conventional navigation due to the assumptions of rigid transformation. Moreover, the ability to accurately quantify spinal alignment in the operating room would provide an assessment of the surgical product via metrics that correlate with clinical outcomes. A method for deformable 3D-2D registration of preoperative CT to intraoperative long-length tomosynthesis images is reported for an accurate 3D evaluation of device placement in the presence of spinal deformation and automated evaluation of global spinal alignment (GSA). Long-length tomosynthesis ("Long Film," LF) images were acquired using an O-arm imaging system (Medtronic, Minneapolis USA). A deformable 3D-2D patient registration was developed using multi-scale masking (proceeding from the full-length image to local subvolumes about each vertebra) to transform vertebral labels and planning information from preoperative CT to the LF images. Automatic measurement of GSA (main thoracic kyphosis [MThK] and lumbar lordosis [LL]) was obtained using a spline fit to registered labels. The "Known-Component Registration" method for device registration was adapted to the multi-scale process for 3D device localization from orthogonal LF images. The multi-scale framework was evaluated using a deformable spine phantom in which pedicle screws were inserted, and deformations were induced over a range in LL ∼25°-80°. Further validation was carried out in a cadaver study with implanted pedicle screws and a similar range of spinal deformation. The accuracy of patient and device registration was evaluated in terms of 3D translational error and target registration error, respectively, and the accuracies of automatic GSA measurements were compared to manual annotation. Phantom studies demonstrated accurate registration via the multi-scale framework for all vertebral levels in both the neutral and deformed spine: median (interquartile range, IQR) patient registration error was 1.1mm (0.7-1.9mm IQR). Automatic measures of MThK and LL agreed with manual delineation within -1.1°±2.2° and 0.7°±2.0° (mean and standard deviation), respectively. Device registration error was 0.7mm (0.4-1.0mm IQR) at the screw tip and 0.9° (1.0°-1.5°) about the screw trajectory. Deformable 3D-2D registration significantly outperformed conventional rigid registration (p<0.05), which exhibited device registration errors of 2.1mm (0.8-4.1mm) and 4.1° (1.2°-9.5°). Cadaver studies verified performance under realistic conditions, demonstrating patient registration error of 1.6mm (0.9-2.1mm); MThK within -4.2°±6.8° and LL within 1.7°±3.5°; and device registration error of 0.8mm (0.5-1.9mm) and 0.7° (0.4°-1.2°) for the multi-scale deformable method, compared to 2.5mm (1.0-7.9mm) and 2.3° (1.6°-8.1°) for rigid registration (p<0.05). The deformable 3D-2D registration framework leverages long-length intraoperative imaging to achieve accurate patient and device registration over the extended lengths of the spine (up to 64cm) even with strong anatomical deformation. The method offers a new means for the quantitative validation of spinal correction (intraoperative GSA measurement) and the 3D verification of device placement in comparison to preoperative images and planning data.

Late Carboniferous intrusions along the Kalamaili suture zone, southwestern Central Asian Orogenic Belt (CAOB): implications for a tectonic switch from subduction to collision

ABSTRACT A tectonic switch from subduction to collision and/or arc–arc collision is a key issue for understanding accretionary orogenic processes. We present new U-Pb ages, geochemistry, whole-rock Nd and zircon Hf isotope data for a suite of late Carboniferous intrusive rocks along the Kalamaili suture zone of the southwestern Central Asian Orogenic Belt (CAOB) and demonstrate their petrogenesis and the transition of their tectonic settings. Zircon U-Pb dating for the gabbros, diorites, granodiorites, and monzogranites yields ages of 317–301 Ma. The gabbros (311 Ma) were likely derived from partial melting of a mixed source of depleted MORB-like asthenospheric mantle with minor old crustal material; the diorites (301 Ma) from the mixed depleted lithospheric mantle and crustal components; the granodiorites (303 Ma) from the mixed mantle- and crust-derived magmas; and the monzogranites (317 Ma) from melting of the newly underplated basaltic lower crust. Combined with previous data, we have grouped all the intrusive rocks along the Kalamaili suture zone into three phases: 350–340 Ma, 330–320 Ma, and 320–300 Ma. The first phase consists of tholeiitic and high-K calc-alkaline granites, the second phase is composed of high-K calc-alkaline I-type granites with strong deformation, and the third phase comprises voluminous and various rock types (mainly mafic and felsic, including many A-type granites), revealing a magmatic flare-up. The magmatic associations and evolution from the first to the third phase, together with regional geology, suggest a tectonic transition from subduction/accretion (350–340 Ma) through syn-collision (330–320 Ma) to post-collision (or post-accretionary, 320–300 Ma), respectively. This study provides new magmatic evidence for the switch from subduction to collision (arc-arc collision) along the Kalamaili suture zone in the southwestern CAOB.

Unidirectional Carbon Fiber Reinforced Cyanate‐Based Shape Polymer Composite with Variable Stiffness

Cyanate‐based shape memory polymer (CSMP) has the advantages of good mechanical properties and excellent shape memory properties. However, the mechanical properties of polymers are relatively poor at high temperature. This article aims to improve the mechanical properties of CSMP by adding varying contents of unidirectional carbon fibers. The carbon fiber reinforced CSMP composites (CSMPCs) are prepared by vacuum hot pressing of prepregs. Compared with CSMP, the tensile, flexural, and compressive properties of the CSMPCs have significant improvement. By changing fiber content and adjusting temperature, the composites can achieve variable stiffness characteristic. In addition, the CSMPC with fiber content of 15% has excellent shape memory performances including higher recovery rates and faster recovery speeds. A shape memory spring based on CSMPC has strong deformation ability, which can realize large compression and stretching deformation. The CSMPCs make up for the shortcoming of decreased mechanical properties at high temperatures of CSMPs and broaden the application used in high‐temperature environments.

A shift of mantle sources for the post-collisional lavas and tectonic links with synchronous deformation in the SE Tibetan Plateau

Strong post-collisional deformation and contemporaneous magmatic flare-ups during the Cenozoic indicate large-scale continental lithospheric modification in the southeastern (SE) Tibetan Plateau. However, the relationship between regional deformation and magmatism is poorly understood. In this paper, we report for the first time the presence of 32–17 Ma mafic rocks within the Ailaoshan-Red River shear zone (ARSZ) and provide new insights into the correlation between deformation and magmatism. Using 369 Cenozoic mafic and felsic rocks (this study and literature data) in and around the ARSZ, we document a continuous magmatic record that delineates a consecutive depletion of their mantle sources through time, which is correlated with the development of regional deformation. The spatial distributions, rock associations, and geochemical features of these rocks indicate a three-stage magmatic evolution in the SE Tibetan Plateau. During the earliest episode (40–32 Ma), the strong emplacement of both mafic and felsic rocks shows a planar-shaped geographic distribution. The second episode (32–17 Ma) is characteristic of voluminous mylonitized granites and minor basaltic rocks generally along the ARSZ. The latest episode (<17 Ma) magmatic rocks are sporadically exposed with dominant OIB-type basaltic rocks and minor A-type granites. From the earliest to the latest episodes, the mafic rocks exhibit progressive depletion in SrNd isotopic compositions, with initial Sr isotopic ratios and εNd(t) values from 0.70509 to 0.71151 and − 12.5 ~ −0.3 to 0.70313–0.70734 and − 3.9 ~ +8.1, respectively. These data, together with the covariations in the (Nb/La)PM and Zr/Nb ratios, signify a dramatic mantle-source shift from enriched to depleted through time for these Cenozoic mafic rocks. Mafic rocks from the earliest episode were generated from an enriched lithospheric mantle through convective thinning. In contrast, the OIB-type basalts from the latest episode were pure asthenospheric magma from decompression melting. Therefore, we propose an interdependent evolution between the shift of mantle sources and the development of synchronous deformation in and around the ARSZ. Our discovery of 32–17 Ma mafic rocks stands as the first direct evidence for the key role of the synchronous development of the lithospheric-scale ARSZ in the shift of mantle sources, asthenospheric melt transportation, and heating-induced crustal magma generation.

Integrated Collaborative Control of “Shielding-Filling-Grouting” of 1 km Deep Large-Section Roadways: A Case Study

Effective control of deformation failure of surrounding rock in deep roadway has become an important prerequisite for the safe and efficient development of deep coal resources. In this study, the field measurement of the study area’s in-situ stress was carried out for the specific engineering geological conditions of the KCM −967 m level west-wing main track roadway. The west-wing main track roadway’s full-section deformation failure features were summarized and analyzed, and the main roadway’s surrounding rock nonlinear deformation failure mechanism was revealed from the perspective of elastoplastic mechanics. Based on that, a set of highly targeted integrated collaborative control technology of “shielding-filling-grouting” system was proposed. The industrial field test revealed that, after the above integrated collaborative control scheme was adopted, there was no strong deformation failure on the surface of the main roadway surrounding rock and deep rock mass, which played the role of active and passive support collaborative control, reduced the subsequent repeated repair and maintenance workload of the roadway, and satisfied the needs of long-term safe and efficient production of the mine. The results obtained provide a reference for the control of surrounding rock of deep and large-section roadways in other mining areas.