Analysis Of Stress-strain Curves Research Articles

The Performance of Niobium-Microalloying Ultra-High-Strength Bridge Cable Steel during Hot Rolling.

This study focuses on exploring the effects of niobium (Nb)-microalloying on the properties of steel for ultra-high-strength bridge cables during hot-rolling processes. We employed a combination of dual-pass compression tests, stress-strain curve analysis, and Electron Backscatter Diffraction (EBSD) techniques to investigate the influence of Nb-microalloying on the static recrystallization behavior and grain size of the steel. The key findings reveal that Nb-microalloying effectively inhibits static recrystallization, particularly at higher temperatures, significantly reducing the volume fraction of recrystallized grains, resulting in a finer grain size and enhanced deformation resistance. Secondly, at a deformation temperature of 975 °C, Nb-containing steel exhibited finer grain sizes compared to Nb-free steel when held for 10 to 50 s; however, the grain size growth accelerated when the hold time exceeded 50 s, likely linked to the increased deformation resistance induced by Nb. Lastly, this research proposes optimal hot-rolling process parameters for new bridge cable steel, recommending specific finishing rolling temperatures and inter-pass times for both Nb-containing and Nb-free steels during the roughing and finishing stages. This study suggests optimal hot-rolling parameters for both Nb-containing and Nb-free steels, providing essential insights for improving hot-rolling and microalloying processes in high-carbon steels for bridge cables.

Mechanical properties and microstructure of waterborne polyurethane-modified cement composites as concrete repair mortar

With the increase in service life, the durability of a large number of concrete structures deteriorates year by year under the influence of the external environment, requiring urgent repair and reinforcement. Ordinary cement concrete materials have disadvantages such as high brittleness, low tensile strength, poor bonding ability, and insufficient durability, making it difficult to meet the repair needs of high-quality building structures. Therefore, self-synthesized anion WPU was used to study its effect on the mechanical properties of cement-based repair mortar. The research found that waterborne polyurethane (WPU)-modified cementitious composite repair materials exhibit better bonding strength with old concrete substrates compared to traditional cement-based materials. Additionally, the incorporation of WPU significantly reduces the brittleness of the repair material, ensuring enhanced efficiency in the repair process. However, according to the hydration heat test results, the addition of WPU delays the hydration process of the composite repair materials. In addition, the addition of WPU enhances the flexibility and bonding ability of the materials, with flexural strength and tensile strength at the age of 28 days reaching 13 MPa and 6 MPa, respectively. Through stress‒strain curve analysis, it was found that the maximum strain amplification of WPU cement mortar can reach 134 %. Combined with SEM testing, it was observed that cured WPU films were present in specimens aged 28 days with P/C ratios of 10 % and 15 %. WPU and cement hydration products permeate each other, forming a three-dimensional polymer network structure, improving the pore structure, and fully exerting the flexibility of WPU. This also validates the experimental results of increased ultimate tensile strain. WPU cement-based composite repair materials have higher bonding strength at a high P/C ratio (15 %), and WPU alone, used as an interface agent for pretreating the interface of old concrete, can improve the interface bonding strength, up to twice that of the group without the surface agent.

Study on mechanical characteristics and damage model of layered sandstone after high temperature action

Rock engineering, which includes slopes, tunnels, and mines, often encounters stratified rocks. These projects are also frequently exposed to special environments of high temperatures, such as deep underground or fire-related conditions. It is of significant importance to conduct research on the damage characteristics and constitutive models of stratified rocks under high-temperature conditions to accurately reflect the influences of rock structure characteristics, geological conditions, and load effects on the damage and deformation characteristics of rock engineering. Under five temperature conditions (20, 200, 400, 600, 800 ℃), the intact sandstone rock samples and the layered sandstone samples are subjected to high-temperature treatment, followed by triaxial compression tests. Based on existing research on statistical damage constitutive models for rocks, a high-temperature layered rock statistical damage constitutive model is established by introducing the Weibull distribution function and high-temperature, bedding, and load coupling damage variables, under the condition that the microelement strength follows the Drucker-Prager (D-P) criterion. The results indicate that the peak strength, damage threshold, elastic modulus, and longitudinal wave velocity show a "U"-shaped trend with an increasing bedding angle, with an opening upwards. As the temperature increases, the anisotropy of the rock initially increases and then decreases, with obvious ductile characteristics after the temperature reaches 600 ℃. The analysis of damage threshold, stress-strain curve, and macroscopic failure morphology shows that the 60° dipping angle sandstone is prone to undergo compressive-shear failure along the weak plane of bedding, exhibiting low toughness mechanical characteristics. Theoretical curves of the statistical damage constitutive model for high-temperature rock are in good agreement with the Triaxial shear test curve of sandstone, which indicates that the constitutive model can reflect the stress-strain process of layered sandstone after high-temperature action, and verifies the applicability of the model. This model does not include unconventional mechanical parameters and can reflect the ductility, brittleness, and strength characteristics with clear physical meanings. The findings of the study can offer theoretical support for computing and numerically modeling rock mechanics after high-temperature action.

Eigenvalue analysis of stress-strain curve of two-dimensional amorphous solids of dispersed frictional grains with finite shear strain.

The stress-strain curve of two-dimensional frictional dispersed grains interacting with a harmonic potential without considering the dynamical slip under a finite strain is determined by using eigenvalue analysis of the Hessian matrix. After the configuration of grains is obtained, the stress-strain curve based on the eigenvalue analysis is in almost perfect agreement with that obtained by the simulation, even if there are plastic deformations caused by stress avalanches. Unlike the naive expectation, the eigenvalues in our model do not indicate any precursors to the stress-drop events.

Low temperature plasticity of microcrystalline Al–Li alloy

The plastic deformation of Al-3.8 at.% Li polycrystals processed by the equal-channel angular hydroextrusion (ECAH) were investigated during tension in the temperature range of 4.2–400 K. The evolution of the microstructure during loading was studied by the electron backscatter diffraction (EBSD) method, including the orientation and kernel average misorientation (KAM) mappings. In as-prepared state the microstructure characterized by grains with small misorientation angles and a high density of dislocations. The deformation of a sample at 120 K leads to increase in the density of deformation defects while at 290 K to their decrease. The strong temperature sensitivity of the yield strength indicates the thermally activated nature of the plastic deformation. An increase in the plasticity and strength of polycrystals with decreasing temperature is explained by a decrease in the dislocation annihilation due to a decrease in the mobility of atoms, resulting in increase in the strain hardening rate. A nonmonotonic dependence of the activation volume Va(T) with a maximum at 180 K was established from stress relaxation data. The analysis of stress-strain curves and microstructure evolution indicate a dominance of thermally activated mechanism of intersection of the forest dislocations below 180 K and an increase in the activity of recovery processes at moderate temperatures.

Deformation behavior of a new Ni-Co base superalloy GH4251 during hot compression

The deformation behavior of a new Ni-Co base superalloy GH4251 under hot compression tests within the deformation strain window of 0.36 to 1.2 was investigated in the temperature range of 1050 ∼ 1170 °C and strain rate range of 0.001 ∼ 1 s−1. Based on the analysis of true stress-strain curves, constitutive equations were established to describe the rheological behavior during hot compression. Microstructure evolution was investigated by transmission electron microscope (TEM), scanning electron microscope (SEM) and optical metallography (OM). The results show that flow behavior of GH4251 alloy is combinedly determined by the effect of work hardening and dynamic recrystallization (DRX). The deformation activation energies at strain of 0.36 to 1.2 are calculated to be 311 ∼ 536 kJ mol−1 in the super-solvus temperature region, and 796 ∼ 1064 kJ mol−1 in the sub-solvus temperature region. The recrystallization nucleation mechanism of GH4251 alloy is strain induced grain boundary migration (SIBGM). The occurrence and expansion of recrystallization are strongly promoted by high deformation temperatures and high strain rates, while the DRX grain size increases with elevated deformation temperature. When the deformation temperature is below 1090°C, the recrystallized grain can be extremely small (<17μm), which is rather independent on strain and strain rate. However, above 1110 °C the grain size at strain rate of 0.001s−1 is significantly larger than that of higher strain rates. The difference can be ascribed to the presence of γ′ phase, with which the development of dynamic recrystallization is postponed, while the growth of recrystallized grains is inhibited as well.

Research on hot deformation behavior and constitutive model to predict flow stress of an annealed FeCrCuNi2Mn2 high-entropy alloy

In the present study, the hot deformation and dynamic recrystallization behaviors of an annealed FeCrCuNi2Mn2 high-entropy alloy were investigated through the hot compression tests. Flow curves were evaluated within a certain temperature range (700–1000 °C) and initial strain rate range (0.001–0.1 s−1), and the corresponding microstructures were assessed. Constitutive equations with strain-dependent material constants were established for the calculation of material constants and for modeling of flow stress behavior through the analysis of true stress-strain curves. The critical and peak stress and strain (dynamic recrystallization parameters) were extracted from the work hardening rate against stress curves. These parameters were then used to determine the recrystallized volume fraction under different conditions. The results indicated that with the increase in deformation temperature and decrease in strain rate, dynamic recrystallization parameters decreased. This trend was followed by an increase in recrystallized volume fraction and grain growth, resulting in a decrease in the hardness value of the alloy. Findings further revealed that the flow stress in the annealed alloy was higher compared with that in the as-cast alloy under the same deformation conditions. Microstructural observations and the evaluation of work hardening rate against stress curves showed the typical dynamic recrystallization characteristics as the dominant softening mechanism under different deformation conditions. The activation energy of hot deformation was determined to be 437 kJ/mol. In the present study, a power equation was established between critical stress and strain and the Zener–Hollomon parameter with the exponents of 0.089 and 0.086, respectively. Moreover, the dynamic recrystallization grain size was found to be proportionate to Z−0.11.

Investigation on the strengthening behaviour of micro-scale copper fiber

Due to the size effect, the material exhibits the characteristics of "the smaller, the stronger", but there are limits to the improvement of material strength. In this paper, the 200 μm pure copper fiber is reduced to 23 μm by the cold drawing method. The stress-strain curve and microscopic analysis, it is concluded that grain boundary strengthening, texture strengthening and dislocation strengthening are the main strengthening methods of copper fiber. Cold drawing improves the fiber strength by reducing the grain size and changing the texture orientations. With the grain refinement, the texture orientation of copper fiber, gradually changed from the random distribution orientations to <001> and <111> preferred orientations. However, the evolution of the texture orientation does not always follow the same path. The increase of <101> oriented grains provide more plastic deformation space for the further refinement of copper fiber. When the fiber diameter reaches 23 μm, the grain orientation deflects to the preferred orientations of <111> and <001> again. For the copper fiber, the conditions for further refinement by orientation transformation gradually disappear, so that the strength of copper fiber approaches the critical value, which can be confirmed by the distribution of grain size at the fracture.

Effect of Nonisoprene Degradation and Naturally Occurring Network during Maturation on the Properties of Natural Rubber.

It well-known that the superior performance of natural rubber (NR) compared to its synthetic counterpart mainly derives from nonisoprene components and naturally occurring network, which varies during the progress of the maturation and thereby results in technically graded rubber with different properties. However, identifying the roles of these two factors in the forming of excellent performance of NR is still a challenge as they change simultaneously during the maturation process. Here, influences of naturally occurring networking and nonisoprene degradation on the components, structures and properties of NR were systematically investigated by tailored treatments of maturation. It was found that the maturation-induced formation of natural network structure contributes to the increase in initial plastic value, Mooney viscosity and gel content for un-crosslinked NR, while the decomposition of nonisoprene components plays a dominant role in improving the mechanical properties of vulcanized NR. Stress-strain curve and Mooney-Rivlin analysis demonstrate that the biodegradation of the nonisoprene components significantly boost the vulcanization process, which significantly increases the number of chemical cross-link networks and effective cross-link density of the material, greatly improving the mechanical properties of NR vulcanizates. This resulted in the tensile strength of TSR 10CV being able to reach 22.6 MPa, which is significantly improved compared to 15.8 MPa of TSR 3CV. Evidenced by tubular model fitting, the increase in chemical cross-linking points effectively reduces the movable radius of the molecular chain under dynamic loading, making the molecular chain more difficult to move, which suppresses the entropy change under dynamic loading and consequently endows NR excellent dynamic mechanical properties. This resulted in a significant decrease in the temperature rising of TSR 10CV to 3.3 °C, while the temperature rising of TSR 3CV was still as high as 14.5 °C. As a minor factor, the naturally occurring network improves the mechanical properties of vulcanizates in the form of sacrificial bonds.

The effect of resting and compression time post-centrifugation on the characteristics of platelet rich fibrin (PRF) membranes.

To evaluate the effect of resting and compression time after centrifugation on the physical properties of platelet rich fibrin (PRF) membranes, and to provide optimal guidance regarding the clinical preparation of PRF. A total of 12 volunteers enrolled in this study divided into 2 groups equally. For each volunteer, 6 tubes of 10mL venous whole blood was drawn. To evaluate the influence of resting time after centrifugation, PRF clots were taken out 0, 1, 3, 5, 7, and 10min from tubes following centrifugation, and then the weight, size, maximum stress, and maximum strain of each group were measured. To evaluate the influence of compression time on the preparation of PRF membranes, the weight ratio of PRF membranes to PRF clots was calculated by compression for 10s, 30s, 60s, 90s, 120s, and 180s, respectively. Scanning electron microscopy was performed to observe the cross-linking of the fibers within membranes, and the maximum stress and strain of PRF membranes were tested followed by stress-strain curve analysis. The weight and volume of PRF clots and PRF membranes increased in size and weight reached the top at 3min, followed by a decrease after 7-min resting. The maximum strain of the PRF membranes after 10min decreased significantly compared to the 3-min and 5-min groups. The maximum stress was found at 3min followed by a statistical decrease when resting time went on. Scanning electron microscopy demonstrated that the internal fibrous structure of the PRF membranes was looser when the compression time was less than 60s when comparing the 90-s group. The maximum stress of PRF membranes was shown using a wait period of 3min post-centrifugation followed by compression for 120s. The findings from the present study demonstrate that the time post-centrifugation of PRF membranes showed a maximum weight, volume, and mechanical properties after resting for 3-5min in the tube post-centrifugation followed by a compression time of 120s. Although research to date has focused primarily on centrifugation protocols, this study revealed for the first time that the resting time post-centrifugation greatly affected the mechanical properties of PRF. This study demonstrated that the resting and compression time after centrifugation influences the mechanical strength of PRF membranes, which might explain differences in PRF characteristics prepared by different clinicians that may provide a standard guide for preparation of PRF membranes.

Preparation of in-situ ZrB2/A356 composites and high-temperature tribological studies

The ZrB2/A356 composite material was prepared by using chemical in situ reaction technology. The high-temperature friction and wear test of ZrB2/A356 aluminum matrix composites was carried out. The friction and wear test temperatures were normal temperatures, 50 °C, 100 °C, 150 °C, 200 °C, 250 °C, and 300 °C. XRD, TEM, SEM, and XPS were used to analyze the microstructure, phase and the formation of surface compounds of the composites under different wear temperatures. The results show that the composite phase is composed of ZrB2 and ɑ-Al, and there is a small amount of Al-Si eutectic phase; ZrB2 particles are small, hexagonal nearly elliptical, flocculent and well bonded to the matrix; Combined with the stress-strain curve and tensile fracture morphology analysis, the composite material is a ductile fracture, and the plasticity of the A356 alloy is higher than that of the composite material; The wear properties of composites are susceptible to temperature changes, and the wear rate is small below 200 °C. The wear mechanism is mainly oxidative wear and abrasive wear. When the temperature reaches above 250 °C, the wear rate begins to rise sharply, and a large number of plastic deformation traces and wear debris appear on the surface of the wear spot, and the surface of the wear debris adheres to the protrusions. The primary wear mechanism is adhesive wear. In the stages of oxidative wear, and abrasive wear, although the friction coefficient changes, it is stable. But in the adhesive wear stage, the friction coefficient becomes very unstable and a sharp peak appears. XPS analysis showed that the compounds formed in the wear scar were mainly Al2O3.

Autowave Criteria of Fracture and Plastic Strain Localization of Zirconium Alloys

Plastic deformation and fracture of Zr–1% Nb alloys exposed to quasi-static tensile testing have been studied via a joint analysis of stress-strain curves, ultrasound velocity and double-exposure speckle photographs. The possibilities of ductility evaluation through the εxx strain distribution in thin-walled parts of zirconium alloys are shown in this paper. The stress-strain state of zirconium alloys in a cold rolling site is investigated considering the development of localized deformation bands and changes in ultrasound velocity. It is established that the transition from the upsetting to the reduction region is accompanied by the significant exhaustion of the plasticity margin of the material; therefore, the latter is more prone to fracture in this zone exactly. It is shown that traditional methods estimating the plasticity margin from the mechanical properties cannot reveal this region, requiring a comprehensive study of macroscopically localized plastic strain in combination with acoustic measurements. In particular, the multi-pass cold rolling of Zr alloys includes various localized deformation processes that can result in the formation of localized plasticity autowaves. Recommendations for strain distribution division over the deformation zone length in the alloy in the pilger roll grooves are provided as well.

The Modeling of the Fracture of Three-Phase Ceramic Composite

In the present study, elastic and strength properties of three-phase Al2O3–ZrB2–SiC composite are investigated based on numerical modeling. Representative volume element (RVE) consisting of Al2O3 matrix, pores, and ZrB2 and SiC inclusions is built based on the experimental data. The uniaxial tension loading of the RVE model under plane strain conditions is considered. The relations of an isotropic elastic-plastic medium with the Drucker–Prager yield criterion are used as constitutive equations. The determination of the effective mechanical properties of the composite is based on the analysis of numerical averaged stress-strain curves. The simulation results demonstrate that the cracks nucleate in the regions of high stress concentration caused by the pore shape. The alumina matrix fractures due to the criterion based on the tensile pressure, while the fracture of inclusions occurs when the criterion based on the accumulated inelastic strain is fulfilled. The influence of the fraction of SiC inclusions on the effective elastic properties of the composite material was studied. It was shown that the elastic moduli weakly depend on the increase of SiC volume fraction in the considered range from 0 % to 34 %.

Crack-Bridging Property Evaluation of Synthetic Polymerized Rubber Gel (SPRG) through Yield Stress Parameter Identification.

Yield stress parameter derivation was conducted by stress-strain curve analysis on four types of grout injection leakage repair materials (GILRM); acrylic, epoxy, urethane and SPRG grouts. Comparative stress-strain curve analysis results showed that while the yield stress point was clearly distinguishable, the strain ratio of SPRG reached up to 664% (13 mm) before material cohesive failure. A secondary experimental result comprised of three different common component ratios of SPRG was conducted to derive and propose an averaged yield stress curve graph, and the results of the yield stress point (180% strain ratio) were set as the basis for repeated stress-strain curve analysis of SPRGs of up to 15 mm displacement conditions. Results showed that SPRG yield stress point remained constant despite repeated cohesive failure, and the modulus of toughness was calculated to be on average 53.1, 180.7, and 271.4 N/mm2, respectively, for the SPRG types. The experimental results of this study demonstrated that it is possible to determine the property limits of conventional GILRM (acrylic, epoxy and urethane grout injection materials) based on yield stress. The study concludes with a proposal on potential application of GILRM toughness by finite element analysis method whereby strain of the material can be derived by hydrostatic pressure. Comparative analysis showed that the toughness of SPRG materials tested in this study are all able to withstand hydrostatic pressure range common to underground structures (0.2 N/mm2). It is expected that the evaluation method and model proposed in this study will be beneficial in assessing other GILRM materials based on their toughness values.

Machine learning-based constitutive models for cement-grouted coal specimens under shearing

Cement-based grouting has been widely used in mining engineering; its constitutive law has not been comprehensively studied. In this study, a novel constitutive law of cement-grouted coal specimens (CGCS) was developed using hybrid machine learning (ML) algorithms. Shear tests were performed on CGCS for the analysis of stress-strain curves and the preparation of the dataset. To maintain the interpretation of the trained ML models, regression tree (RT) was used as the main technique. The effect of maximum RT depth (Max_depth) on its performance was studied, and the hyperparameters of RT were tuned using the genetic algorithm (GA). The RT performance was also compared with ensemble learning techniques. The optimum correlation coefficient on the training set was determined as 0.835, 0.946, 0.981, and 0.985 for RT models with Max_depth = 3, 5, 7, and 9, respectively. The overall correlation coefficient was over 0.9 when the Max_depth ≥ 5, indicating that the constitutive law of CGCS can be well described. However, the failure type of CGCS could not be captured using the trained RT models. Random forest was found to be the optimum algorithm for the constitutive modeling of CGCS, while RT with the Max_depth = 3 performed the worst.

Analysis of Stress-Strain Curves to Predict Dynamic Recrystallization During Hot Deformation of M300 Grade Maraging Steel

18Ni-2000 MPa maraging steel (M300 grade) is extensively used for performance critical aerospace applications where strength-toughness balance is the basis for material selection. The key to achieve the desired mechanical properties in the final product is to process the material under conditions that will impart an equiaxed, fine grained microstructure. This in turn is controlled by the selected deformation processing conditions such as strain, strain rate and temperature. Therefore, hot deformation behavior of the material is usually studied under wide temperature, and strain rate ranges to map the microstructural evolution with specimens deformed to a given strain. However, the effect of strain on the microstructural evolution, its effect on the initiation and termination of dynamic recrystallization are essential to obtain balanced mechanical properties. In this study, analysis of stress-strain curves was conducted with an intention to obtain fine prior austenite grain (PAG) size through dynamic recrystallization (DRX), and the same was verified experimentally from the microstructures evolved through hot isothermal compression tests on cylindrical specimens subjected to different strains. A single peak type DRX curve was identified for analysis from the high temperature stress-strain curves. The theoretically determined critical strain was used to experimentally verify the initiation of DRX (DRXI) and transition from DRX dominant region to grain growth dominant region (DRXT). Hot isothermal compression tests have been conducted at T=1100°C and e = 0.1s−1 and obtained PAG size of 7.68 µm in the specimen deformed to theoretically determined optimum strain of 0.6, thereby validating the used models.

Materials Characterisation and Fracture Mechanism of Recycled Aluminium Alloy AA6061 Reinforced with Alumina Oxide

This manuscript characterises the tensile behaviour and fracture mechanism of recycled aluminium alloy AA6061 reinforced with alumina oxide undergoing finite strain deformation of a uniaxial tensile test. The tests are conducted at three different strain rates of 6×10−3s−1, 6×10−2s−1, and 6×10−1s−1, at room temperature. The specimens are primarily examined in terms of stress-strain curves and microstructural analysis. The stress strain curve analysis is compared with the primary aluminium alloy AA6061. In general, the flow stress of both materials increases with increasing strain rate. The microstructures are investigated using Field-Emission Scanning Electron Microscopy (FESEM). The analysis on the deformed specimens showed that the deformation is driven by a ductile fracture mechanism via voids nucleation, and sensitive to the strain rate changes. The results of this work provide valuable information to improve the existing recycling process before an appropriate engineering application can be established in relevant areas.

The Domain of Portevin-Le Chatelier Effect in Al-3Mg Alloy

An Al-3Mg (wt. %) alloy was studied after equal channel angular pressing and subsequent cold rolling. The mechanical behavior of the alloy in the temperature range from 223 K to 373 K (from –50°C to 125°C) at strain rates 2.1×10–1 – 5.2×10–5 s–1 was investigated. The analysis of stress-strain curves was performed to determine the conditions of manifestation of the Portevin – Le Chatelier (PLC) effect in investigated alloy. The deformation curve at a temperature of 298 K (25°C) and a strain rate of 1×10–3 s–1 is characterized by instability of plastic flow in contrast to the deformation curves obtained under other studied strain rate/temperature conditions. Stress oscillations at the necking stage were observed at high temperatures (&gt;323 K (50°C)) and lower strain rates (1×10–4 s–1 and 5.2×10–5 s–1) forming the left border of the PLC effect domain. In general, deformation curves are characterized by the absence of stress serrations during the uniform elongation.

Segregated Network Polymer Composites with High Electrical Conductivity and Well Mechanical Properties based on PVC, P(VDF-TFE), UHMWPE, and rGO.

The formation of a segregated network structure (wittingly uneven distribution of a filler) is one of the most promising strategies for the fabrication of electrically conductive polymer composites at present. However, the simultaneous achievement of high values of electrical conductivity with the retention of well mechanical properties within this approach remains a great challenge. Here, by means of X-ray photoelectron spectra (XPS), near-edge X-ray absorption fine structure (NEXAFS) spectra, scanning electron microscopy (SEM), dielectric spectroscopy, and compression engineering stress–strain curve analysis, we have studied the effect of a segregated network structure on the electrical conductivity and mechanical properties of a set of polymer composites. The composites were prepared by applying graphene oxide (GO) with ultralarge basal plane size (up to 150 μm) onto the surface of polymer powder particles, namely, poly(vinyl chloride) (PVC), poly(vinylidene fluoride-co-tetrafluoroethylene) (P(VDF-TFE)), and ultrahigh-molecular-weight poly(ethylene) (UHMWPE) with the subsequent GO reduction and composite hot pressing. A strong dependence of the segregated network polymer composites’ physical properties on the polymer matrix was demonstrated. Particularly, 12 orders of magnitude rise of the polymers’ electrical conductivity up to 0.7 S/m was found upon the incorporation of the reduced GO (rGO). A 17% increase in the P(VDF-TFE) elastic modulus filled by 1 wt % of rGO was observed. Fracture strength of PVC/rGO at 0.5 wt % content of the filler was demonstrated to decrease by fourfold. At the same time, the change in strength was not significant for P(VDF-TFE) and UHMWPE composites in comparison with pure polymers. Our results show a promise to accelerate the development of new composites for energy applications, such as metal-free supercapacitor plates and current collectors of lithium-ion batteries, bipolar plates of proton-exchange membrane fuel cells, antistatic elements of various electronic devices, etc.

The Application of Dynamic Shock Mechanics Test in Engineering Blasting

With the continuous advancement of China's infrastructure construction to the west, according to the geographic situation in the southwest region, such as mountainous areas and complex terrain, the road construction process is inevitably accompanied by earth and rock blasting. To improve the quality and safety of the project, this paper addresses the problems of land and rock blasting faced in the construction of mountain road projects, taking the research of rock dynamic mechanics test as the starting point, and using a combination of theoretical analysis and experimental research methods. The specific research content includes the following parts: dynamic impact compression test (SHPB), dynamic splitting tensile test, and stress-strain curve analysis of the test results, which provides the theoretical basis and numerical parameters for the numerical simulation of future engineering blasting.