Elastic Deformation Process Research Articles

Deformation and Failure Mechanism and Control of Water-Rich Sandstone Roadways in the Huaibei Mining Area

The sandstone roof rock in the Huaibei mining area contains abundant water at depths of 2–3 m. Water–rock interactions in the rock-surrounding roadway can cause significant deformation, seriously threatening the safety of mine operations. Investigating the deformation and failure mechanisms of water-rich sandstone is therefore of critical importance. In this study, X-ray diffraction and scanning electron microscopy were used to analyze the composition and microstructure of water-rich sandstone. Based on the stress state during the roadway excavation, a true triaxial loading scheme with four different stress paths was designed to study the effects of different moisture contents and loading methods on the mechanical properties of the sandstone. The results show that the deviatoric stress decreased for all stress paths. Acoustic emission (AE) characteristics during the deformation and failure processes were also studied, which indicated that the AE b-value decreased, increased, and then decreased again corresponding to the primary compaction, elastic deformation, and plastic deformation evolutionary processes in the internal microstructure of the rock. The variation in the b-value reflected the development and expansion of internal fractures. These findings provide useful insights for controlling the stability of the surrounding rock in water-rich roadways in coal mines.

Получение и обработка акустических откликов волн Лэмба в датчиках водных растворов базовых вкусов

In this work, the total acoustic wave losses in 128°Y-LiNbO3 wafers during liquid application due to radiation emission of waves into the liquid medium, as well as its viscosity, conductivity, density and dielectric constant of the liquid analyte are measured. Solutions with 5 basic flavors, widely used for calibration and reference creation in liquid media testing, were selected as test liquids. The measurements were performed in the range of 30...60 MHz. After the measurements, the experimental data were presented in the form of polar histograms, from the comparison of areas and shapes of which the flavor of a particular liquid was determined. Then, a principal component analysis (PCA) method was applied to the same experimental results to describe linear elastic wave deformation processes based on experimental data containing known values of physical wave measurements for different types of liquid media, which was previously used to identify gases and predict the properties of various substances from the linear response of a normal acoustic-electronic wave. In this paper, a comparative analysis of the results obtained using polar histograms and the standard PCA classification method is performed. The advantages of the latter are demonstrated. The results of this study are useful both for the development of acoustic sensors without sensor layers and for the application of machine learning methods to data in other types of sensors.

Effect of interlayer interfaces enriched with multi-walled carbon nanotubes network on microstructure and mechanical properties of carbide-based composite coatings

In this paper, a WC-20Cr3C2-7Ni/multi-walled carbon nanotubes (MWCNTs)-Ni composite powder with a core-shell structure was prepared by surface modification and electroless nickel plating. After high-velocity oxy-fuel (HVOF) spraying, MWCNTs enriched in the shell and reinforced the interlayer interface of the composite coating. The addition of 0.2 wt% MWCNTs increased the reduced modulus and energy dissipation capacity of the composite coating by 12.6 % and 25.0%, respectively. The HRTEM results showed that MWCNTs formed a network structure at the interface. During the deformation process, stress was effectively transferred to network MWCNTs due to the strong metallurgical bond between MWCNTs and the binder phase. It allowed MWCNTs to absorb more energy and promoted stress to be transferred to the interior along the interlayer interface. The influence of MWCNTs on the elastic deformation process of the coatings was analyzed by numerical simulation.

In-situ EBSD study of the multiple deformation modes of a TiNb/Nb/NiTi multilayer composite

In the current work, a Ti72.8Nb27.2/Nb/Ni50.9Ti49.1 multilayer composite was fabricated to elucidate the contribution of multiple deformation modes to the mechanical properties with respect to the material. The composite, which consists of a TiNb component, intermediate Nb layers and NiTi component, shows a well-bonded metallurgical interface. The in-situ EBSD results indicated that B2 and β-Nb experienced elastic deformation at macroscopic strains below 1.3% during loading. As the strain range increased from 1.3% to 9.5%, B2 underwent stress-induced martensitic transformations (SIMTs) from B2 to B19′, while β-Nb experienced mainly plastic deformation. In the case of β-TiNb, the process of elastic deformation, plastic slip, and deformation twinning occur within the macroscopic strain ranges of 0%–2.5%, 2.5%–5.3%, and 5.3%–9.5%, respectively. The deformed composite, comprising of B19′ martensite, β-TiNb/Nb, TiNb twins, and B2 parent phases, exhibited both elastic recovery (ranging from 9.5% to 8.8%) and partially reversible B19′ to B2 SIMTs (ranging from 9.5% to 7.8%). Once unloaded, a significant macroscopic residual strain is retained at 7.8%, since the partially reversible B19′ → B2 SIMTs, potential plastic deformation and deformation twinning.

Thermal-Diffusive Processes of an Electron-Hole Non-Local Semiconductor Model with Variable Thermal Conductivity and Hall Current Effect

In this work, a novel model is presented that describes thermal diffusion processes through non-local semiconductor materials. The material under study is subjected to the influence of a strong magnetic field, which creates a Hall current. Interference between the excited electrons and the excited holes of a non-local semiconductor that had been exposed to temperature was present, and thermal conductivity depending on changes in graduated temperature were accounted for. The governing equations are written in a dimensionless form in one dimension (1D) where the thermal conductivity is taken as a function of temperature through electronic and elastic deformation (ED and ED) processes. Laplace transforms in one dimension with initial conditions were used to convert partial differential equations to arrive at exact formulas of solutions. To obtain the exact linear solutions, some boundary conditions taken on the free surface of the non-local semiconductor were used. Using numerical methods of inverse Laplace transforms, the complete solutions of the physical quantities under study were obtained. To further understand how various variables (thermal memory, variable thermal conductivity, and Hall current) affect the non-local semiconductor, numerical physical fields were simulated, and are graphically depicted, and discussed herein.

1 0 0] Dislocation core extension and decomposition in BCC bicrystal under biaxial loading

The evolution of grain boundary dislocation structure under biaxial tension–compression loading is simulated by the phase field crystal (PFC) method for small angle symmetric tilt grain boundary (STGB) of body center cubic (BCC) bi-crystal. Extension of the STGB dislocation core under the strain and the extended width of the core with the strain increasing are studied. In the elastic deformation process under the loading, the extension of the grain boundary dislocation core is accompanied by increasing the strain energy of the system. When the extension of the dislocation core reaches maximum critical width, the extended dislocation core occurs to decompose into three dislocation cores, in which two cores is in no-extended state, the Burgers vector direction of which is in the same direction of the original extended dislocation. The other dislocation core is of the extended type which Burgers vector direction is opposite to the Burgers vector direction of the original extended dislocation core. By establishing the macroscopic energy equation of the extended dislocation core system, it can be well revealed that the elastic strain energy is mainly stored in the extended dislocation defects and the complete lattice of the matrix. At the same time, it also reveals the function relationship between the energy of the extended dislocation core and the width of the extended dislocation during the biaxial loading process of the bi-crystal, as well as the critical condition of energy instability and the change of the energy barrier of the system for the dislocation extension core decomposition.

The elastic deformation process of bimetallic objects

In industrial problems linear elasticity simulation has been known to be successfully solved by the Finite Element Methods (FEMs). However, a mathematical model as well as a numerical solution program that can be applied to the deformation simulation of bimetallic materials are still the challenges in this research area. In this paper, we investigate a mathematical model for the linear elastic deformation of bimetallic structures. By reducing the linear elasticity problem to its weak form, we apply the continuous Galerkin approximation to obtain the discrete problem. The existence and the uniqueness of the solution of the weak problem are clearly demonstrated, ensuring the well-posedness of the problem. In addition, the numerical simulations with bimetallic materials have been built on Freefem[Formula: see text] software that illustrate the efficiency and reliability of the numerical method.

A calculation model of TC4 shot peening residual stress based on elastic-plastic theory

Shot peening is widely used in automobile, aviation, and other industries because it can change the fatigue strength of metal structures by introducing residual compressive stress field on the surface and significantly improve the fatigue life of mechanical structures. In order to improve the surface properties of parts after shot peening, an analysis method for rapidly predicting residual stress of parts surface during shot peening is proposed. During the analysis, an elastoplastic impact model of shot was established, and stress–strain laws in three processes of elastic loading, plastic deformation and stress release were studied. The residual stress under different shot peening parameters was predicted by considering the plastic strengthening effect of TC4 (Ti-6Al-4V). A TC4 shot peening test was performed and residual stress was measured, and the results are consistent with the model predictions, which verified correctness of the model.

Deformation and failure of pseudo-ductile quasi-isotropic all-carbon hybrid FRPS with an open hole under tension

An experimental study has been carried out to investigate the elastic and pseudo-ductile deformation processes of carbon fibre reinforced plastics, containing low elongation (LE) and high elongation (HE) layers of standard thickness. The behaviour of unidirectional homogeneous LE- and HE-laminates, hybrid [HE/LE/HE] and quasi-isotropic composites, with sublaminates sequence [0/45/90/-45]s and [0/60/-60]s were studied up to complete tensile failure. Tests carried out on standard prismatic specimens and specimens with a central hole. A clip-on extensometer and digital image correlation (DIC) were used to distinguish the stable elastic deformation, the microdamage accumulation in the LE-layers, and the delamination of LE and HE layers. For notched specimens, acoustic emission signals revealed the accumulation of scattered microdamage and the localisation of the pseudo-ductility around the hole. The quasi-isotropic hybrid laminates were almost notch insensitive, with the notch sensitivity factors in the open hole tension test for pseudo-yield and ultimate stress below 1.15.

Time-lapse nanometre-scale 3D synchrotron imaging and image-based modelling of the response of shales to heating

The development of pore and fracture networks at the nano-scale as a response to heating can reveal coupled physical relationships relevant to several energy applications. A combination of time-lapse 3D imaging and finite-element modelling (FEM) was performed on two typical thermally immature shale samples, Kimmeridge Clay and Akrabou shale, to investigate thermal response at the nm-scale for the first time. Samples were imaged using Transmission X-ray Microscopy (TXM) with a voxel resolution of 34 nm at the I13–2 beamline at Diamond Light source, UK. Images were taken after heating to temperatures of 20 °C, 300 °C, 350 °C and 400 °C. The initiation of nano-pores within individual minerals and organic matter particles were observed and quantified alongside the evolution from nano-pores to micro-fractures. The major expansion of pore-volume occurred between 300 and 350 °C in both samples, with the pores elongating rapidly along the organic-rich bedding. The internal pressures induced by organic matter transformation influenced the development of microfractures. Mechanical properties and strain distributions within these two samples were modelled under a range of axial stresses using FEM. The results show that the overall stiffness of the shale reduced during heating, despite organic matter becoming stiffer. The varied roles of ductile (e.g., clay minerals, organic matter) and brittle materials (e.g., calcite, pyrite) within the rock matrix are also modelled and discussed. The configurations of organic matter, mineral components, porosity and connectivity impact elastic deformation during shale pyrolysis. This work extends our understanding of dynamic coupled processes of microstructure and elastic deformation in shales to the nm-scale, which also has applications to other subsurface energy systems such as carbon sequestration, geothermal and nuclear waste disposal.

Prediction of diffusion coefficients in fcc, bcc and hcp phases remained stable or metastable by the machine-learning methods

Diffusion coefficient play a crucial role in material designing, and physical phenomenon explaining during the material preparation and post-treatment. However, it is unavailable in some metallic systems. In this paper, based on basic physical properties (including atom properties, lattice parameters, melting temperature, elastic stiffness constant and etc.), the diffusion activate energy model were developed by machine-learning methods. First, the melting temperature (Tm) and elastic stiffness constant (Cij) models were built by machine-learning methods to fill the absent values in properties. Second, the diffusion activate energy (Q) model was built, and a hybrid features selection method was used to decrease features from 73 to 11 in the model. The Tm, Cij and Q models showed a good predictive ability and goodness of fit. Finally, features in the models were analyzed and compared with the parameters in various prior models. This work provides further understanding on the mechanism of the melting process, elastic deformation and diffusion process. Moreover, the models could be able to provide an easy and reliable method to obtain the diffusion coefficients in bcc, fcc, and hcp alloys when they are needed but unavailable.

Localized fault-zone dilatancy and surface inelasticity of the 2019 Ridgecrest earthquakes

Earthquakes produce a spectrum of elastic and inelastic deformation processes that are reflected across various length and time scales. While elasticity has long dominated research assumptions in active tectonics, increasing interest has focused on the inelastic characteristics of earthquakes, particularly those of the surface fault rupture zone itself, and how they relate to ground rupture hazard and the mechanics of damage zones. Here we present detailed co-seismic surface-strain analysis of the 2019 Ridgecrest, California, earthquakes. We derive three-dimensional high-resolution surface displacements from satellite optical imagery, which we then invert for the co-seismic surface-strain tensors. We show that fault-zone dilation is pervasive throughout these earthquakes and that inelastic failure is present but relatively localized (median width of 31 m). The width of the inelastic failure zone is not correlated to off-fault deformation, surface geology or displacement magnitude. Instead, the extent and kinematics of inelastic failure reflect active, mylonitic deformation of the fault damage zone that is influenced by rupture velocity and fault maturity. These results highlight how a single earthquake contributes to the long-term, permanent geologic record of faulting. Inelastic failure in the 2019 Ridgecrest earthquakes was localized and influenced by mylonitic deformation of the fault damage zone, according to an analysis of surface displacements derived from satellite images.

Influence of auxeticity on the processes of elastic deformation in a single crystal VZhM8 in the direction [011

The study of deformation processes in a cylinder made of monocrystalline heat-resistant nickel alloy VZHM8. Different variants of the orientation of the crystallographic axes of a single crystal of a VZhM8 nickel alloy relative to the axis of symmetry of the cylinder when it is shocks an rigid wall (Taylor test) are considered. It is shown that if the [011] direction coincides with the direction of shock loading of the cylinder, the initially circular sections of the cylinder turn into ellipses until the moment of rebound, which is explained by the influence of the negative Poisson’s coefficient.

The meshfree analysis of elasticity problem utilizing radial basis reproducing kernel particle method

The computational accuracy of the traditional reproducing kernel particle method (RKPM) is susceptible to different kernel functions. To eliminate the adverse effects of the different kernel functions on the computational accuracy of the RKPM, the radial basis function (RBF) is introduced and the radial basis reproducing kernel particle method (RRKPM) is proposed. Compared with the RKPM, the proposed method has the advantages of greater computational accuracy and faster convergence speed. Furthermore, the proposed method is applied to analyze the elastic deformation process of materials with various defects. Utilizing the Galerkin weak form of elastic mechanical problem, the RRKPM of elastic mechanics is established and the corresponding formulae are derived. Combined with the numerical examples, the shaped parameter of the RBF, the scaling parameter and the penalty factor are discussed. Finally, several different examples are adopted to demonstrate the applicability and correctness of the RRKPM.

Numerical Study on the Elastic Deformation and the Stress Field of Brittle Rocks under Harmonic Dynamic Load

In order to study the deformation displacement and the stress field of brittle rocks under harmonic dynamic loading, a series of systematic numerical simulations are conducted in this paper. A 3D uniaxial compression simulation is carried out to calibrate and determine the property parameters of sandstone and a model of the cylindrical indenter intruding the rock is proposed to analyze the process of elastic deformation. Four main parameters are taken into account, namely the position on the rock, the frequency and the amplitude of dynamic load, the type of indenter and the loading conditions (static and static-dynamic). Based on the analysis undertaken, it can be concluded that both of the deformation displacement and stress field of the rock change in a harmonic manner under the static-dynamic loads. The frequency and the amplitude of harmonic dynamic load determine the period and the magnitude of the rock response, respectively. In addition, the existence of harmonic dynamic load can aggravate the fatigue damage of the rock and allow a reduction in static load. Our investigations confirm that the static-dynamic loads are more conducive to rock fracture than static load.

Global well-posedness theory for a class of coupled parabolic-elliptic systems

We consider a fully coupled system consisting of a parabolic equation, with boundary and initial conditions, and an abstract elliptic equation in a variational form with time as a parameter. Such systems appear in applications related to the modeling of coupled diffusion and elastic deformation processes in inhomogeneous porous media within a quasi-static assumption. We establish the global existence, uniqueness, and continuous dependence on initial and boundary data of a weak solution to the system. The proof of this result involves the proposed pseudo-decoupling method which reduces the coupled system to an initial-boundary value problem for a single implicit equation and a refined approach to deriving a priori energy estimates based on component-wise contributions of system parameters to energy norms.

Mechanical properties of the three-dimensional compression-twist cellular structure

The cellular structure can exhibit many special mechanical behaviors due to its variable cell shape. A three-dimensional compression-twist cell structure based on the rotation mechanism of two-dimensional chiral cell structure is developed, which has twist deformation under axial compression. The shape of three-dimensional compression-twist cell structure is determined through cell angle, cell length, and thickness ratio. Analytical expressions of effective Young’s modulus, Poisson’s ratio, and twist angle are derived by using beam theory, which have a good agreement with the finite element calculations and the deformation process of the cell is discussed. To work on the effect of geometric parameters of cell on the mechanical properties, a finite element analysis model of compression-twist cell structure is carried out, which shows the process of elastic and plastic deformation under compression. Effects of cell angle, cell length, and thickness ratio are fully discussed, which indicate that cell angle has obvious nonlinear effect on relative twist angle and could stiffen it. Finally, a compression-twist cell structure sample is made through three-dimensional printing, and an in-plane compressive experiment is carried out to prove analytical and finite element analysis results.

Mathematical simulation of particle impact on a fixed surface in the formation of powder coatings

The article deals with the process of elastic and plastic-elastic deformation of the particles during forming of the coating layer. Mathematical model of the process of impacting of powder particle on the fixed surface has been developed. Influence of material properties, kinetic and thermal parameters of deposition on the particle deformation has also been considered.

Surface residual stress distribution for face gear under grinding with a long-radius disk wheel

Face gear transmission has been widely used because of its unique technical advantages. The residual stress of a tooth surface after grinding is the key factor affecting the surface quality of gear teeth. To improve the performance of tooth surfaces and better guide the grinding test, it is necessary to develop a method to analyse the residual stress of face gear after grinding with a long-radius disk wheel. First, a mathematical model of the grinding face gear with a long-radius disk wheel is established. Then, the basic parameters affecting face gear grinding are studied, and mathematical calculation models, including the grinding force and grinding heat, are established. On this basis, the three processes of elastic loading, plastic deformation and stress release are studied, and a mathematical model of the residual stress of face gear grinding is established. Finally, face gear grinding tests are carried out; the residual stress is determined, and the model is verified by experimental data. Through the study of the surface residual stress distribution of face gear under grinding with a long-radius disk wheel, the grinding process can be further guided to improve the grinding quality and can be extended to the analysis of residual stress distribution after grinding of other complex surface parts.

Development of ultra-high molecular weight polyethylene-functionalized carbon nano-onions composites for biomedical applications

Herein, carbon nano-onions (CNOs) were covalently functionalized with mercaptophenyl methacrylate (MPMA) and ultra-high molecular weight polyethylene/functionalized carbon nano-onions (UHMWPE/f-CNOs) nanocomposites were prepared for the first time. UHMWPE/f-CNOs composites were fabricated by solution mixing followed by hydraulic pressing. The surface chemical structure of f-CNOs, morphology, microstructural properties, thermal stability, and decomposition, crystallinity, mechanical and cytotoxicity of the nanocomposites were evaluated. Biocompatibility assessments of these nanocomposites were studied with the human osteoblast cells. In vitro results displayed excellent cell growth and viability on the surface of nanocomposites over 14 days of incubation without significant cytotoxicity. The cytotoxicity of f-CNOs to osteoblast was depended on its concentration. Increasing the concentration of f-CNOs (0.1 wt%) in UHMWPE improved the biocompatibility of the nanocomposite surface to bone cells. In addition, at a high concentration of f-CNOs (0.1 wt%), the nanocomposite showed the highest improvement in tensile strength 83% as compared to neat UHMWPE. Increasing f-CNOs content also leads to enhancement in yield strength, elastic modulus, fracture toughness, and tensile strength. The strengthening of UHMWPE/f-CNOs systems was significantly influenced by the concentration of f-CNOs, which revealed its extent of polymer wrapping and degree of dispersion. The elastic deformation process was influenced by the fraction of f-CNOs oriented along with the tensile axis, whereas the deformation performance in the plastic regime was controlled by the wrapping of polymer and polymer-f-CNOs interfacial strength. Nevertheless, these nontoxic UHMWPE/f-CNOs nanocomposites would pave the way for the manufacture of artificial implants for potential arthroplasty and other biomedical applications.