Strength Characteristics Of Materials Research Articles

Strength and deformation characteristics of construction materials of civil engineering historical sites since the end of the Edo shogunate

Strength and deformation characteristics of construction materials of civil engineering historical sites since the end of the Edo shogunate

Design, fabrication and vibration characteristics of a novel composite auxetic structure embedded with resonators

With the rapid development of shipbuilding and aerospace industries, the mechanical performance requirements for structures are becoming increasingly demanding. Conventional vibration reduction structures cannot meet the requirements for lightweight, high load capacity, low frequency and broadband vibration reduction. Therefore, it is necessary to consider new structural topologies and material systems. Inspired by the lightweight and high strength characteristics of composite materials, the negative Poisson's ratio characteristics and the locally resonating phononic crystal, the carbon fiber composite auxetic structure embedded with resonators is proposed. Embedded resonators within composite auxetic structures can be strategically positioned to introduce gaps, thereby enhancing the vibration damping performance. The basic auxetic structure is prepared by simpler methods including molding and bonding, and the outer shell of resonator is made by 3D printing technology. The method enables the design of appropriate outer shell based on various cavity types within the structure, ensuring a stable connection between resonators and the structure itself. The range of the band gap can be predicted based on the negative effective mass. Vibration behavior and band gap characteristics of the structure are proved through vibration experiments and numerical simulations. It is revealed that the structure can generate local resonant band gaps at lower frequencies. Meanwhile, the coupling relationship between the auxetic structure and the resonator makes an impact to the band gap range. Therefore, the proposed structure can meet the required multi-functional integrated performance requirements. Furthermore, the parametric analysis is carried out, and the relevant conclusions can provide theoretical guidance for designing porous composite structures with effective low-broadband vibration reduction capabilities.

Simplified evaluation method of shear strength characteristics of embankment materials applied to aseismic diagnosis of existing embankments

Simplified evaluation method of shear strength characteristics of embankment materials applied to aseismic diagnosis of existing embankments

Research progress on freeze–thaw constitutive model of concrete based on damage mechanics

Abstract In cold areas, freeze–thaw damage seriously affects the long-term use and safe operation of concrete structures. The constitutive model is an important foundation for predicting deformation and strength characteristics of concrete materials and for the non-linear analysis of concrete structures. This study is based on the elaboration of methods for the constitutive model of damaged materials by using damage mechanics and others. This study focuses on the existing constitutive model results of concrete under the static axial compression load, dynamic load, and coupling environmental load, and analyzing the problems in existing studies. Research has shown that segmented models exhibit higher fitting accuracy of concrete freeze–thaw constitutive model under static axial compression loads. By defining coupled damage variables, it is possible to approach the actual freeze–thaw damage of concrete under environmental coupling, and attention should be paid to the differences or interactions between damage factors. In order to meet the actual engineering needs of high altitude and cold areas needs to expand the temperature range of freeze–thaw tests and consider the dynamic loads impact on concrete damage, the establishment of constitutive model of concrete under the actual freeze–thaw damage is the focus of frost-resistant durability research of hydraulic concrete in cold regions.

Study on Sugarcane Bagasse Biochar in Concrete for Carbon Sequestration

Abstract: Embodied carbon from manufacturing of cement is increasing day by day as constructions are happening everywhere so the consumption of cement is increasing by default. In next decade there are much more constructions are going to takes place that will lead to Increase in GHG’s emissions from cement manufacturing. It is supposed to be a threat to climate . To reduce this increase in embodied carbon there is need to reduce cement consumption by partially replacing cement with other suitable options. biochar which is a by-product of pyrolysis of biomass and is effective in carbon sequestration activity and results in high water and carbon dioxide holding capacity. In this study Sugarcane bagasse biochar is used in concrete and mortar as partial replacement of cement for carbon sequestration. Strength characteristics of materials are supposed to be interlinked with pozzolanic activity hence pretreatment is done with 0.1 N HCl to enhance pozzolanic property activity of biochar. This pozzolanic activity is calculated by considering Ca(OH)2 fixation during the titration in chapelle test. From the study results its is observed that pretreatment with 0.1 N HCl at room temperature is sufficient to increase the pozzolanic activity of biochar also this Sugarcane bagasse biochar is observed to be sequestering carbon dioxide and it is increasing with increase in biochar. But compressive strength of concrete is decreasing with increase in sugarcane bagasse biochar. Hence it is not suitable to be used in construction work but can be used in plaster mortar where no much compressive strength is required . Sugarcane bagasse biochar can act as carbon sequestering media in concrete but it can’t be recommended in concrete or mortar for construction work.

Influence of bacterial cellulose stabilization on strength characteristics of construction earthen materials

Influence of bacterial cellulose stabilization on strength characteristics of construction earthen materials

THE DEVELOPMENT OF A PIEZOELECTRIC DEFECT DETECTION DEVICE THROUGH MATHEMATICAL MODELING APPLIED TO POLYMER COMPOSITE MATERIALS

In this research article, the focus is on examining the strength characteristics of polymer composite materials under various stress states. The investigation into the material dissolution process is conducted in two distinct stages. Initially, the article employs a criterion approach to derive explicit formulas for the latent decay time (incubation period) of materials, considering singular, exponential and Abelian kernels of the damage operator. In the subsequent stage, the classical strength condition is applied to establish a Volterra type integral equation, which characterizes the damage process for hereditary materials. These resulting differential equations are then solved with appropriate initial conditions. The study utilizes the obtained results to create time-dependent graphs of the damage parameter and performs comparisons. A piezoelectric defect detection device for polymer composite materials has been proposed through the application of mathematical modeling.

ДОСЛІДЖЕННЯ МІЦНОСТІ БАГАТОШАРОВИХ ТЕКСТИЛЬНИХ МАТЕРІАЛІВ З ВИКОРИСТАННЯМ МАТЕМАТИЧНОГО МОДЕЛЮВАННЯ

The strength characteristics of multilayer textile materials are important indicators that affect their reliability and durability. When gluing layers of materials, one of the fundamental properties of matter is used - adhesion. Adhesion relative to textile materials is to obtain a non -detachable connection of the textile cloth and the canvas of the base by establishing between them with glue when heated with plastic deformation and further cooling of all components. During operation there is a displacement of layers relative to each other, as a result, the fabric is destroyed as a whole. Therefore, the process of destruction of adhesive connection of layers of textile materials is a consistent deformation of the adhesive and protruding fibers of the fabric and the canvas of the base before displacement, deformation (elongation) or destruction. The authors of the article investigated the influence of the mechanical properties of textile materials on the strength of the adhesive connection of layers of composite materials. A method of fabric strength research using mathematical modeling has been developed, which allows, without time-consuming experimental studies, to predict the loss of strength with known values ​​of the properties of fabric fibers, the number of layers, and the type of glue. On the basis of the theory of gluing of textile materials, theoretical and experimental studies of the strength of the adhesive connection of multilayer materials were carried out. When studying the strength of an adhesive joint, the main indicator is the magnitude of forces during delamination. The process of destruction of the adhesive connection of layers of textile materials in the event of a delamination load is considered as a sequential deformation of the glue with protruding fibers of the fabric and the base fabric until their displacement, deformation (elongation) or destruction.

Strength, Permeability and Multiscale Pore Characteristics of Cement-Based Materials with High-Volume Fly Ash Contents and Different Water-Binder Ratios

Strength, Permeability and Multiscale Pore Characteristics of Cement-Based Materials with High-Volume Fly Ash Contents and Different Water-Binder Ratios

Структура и прочность пористых материалов на основе порошков карбида титана разной дисперсности

Materials with porosity from 67.5 to 82.5 % were obtained from mixtures of titanium carbide powders and ammonium bicarbonate blowing agent by sintering in vacuum at temperatures of 1300 – 1500 °C. X-ray phase analysis of porous materials found that the crystal lattice parameter decreases with increasing sintering temperature. This indicates a decrease in the content of bound carbon C/Ti in titanium carbide. As a result of a comparative study of the obtained according to bending test strength characteristics of materials synthesized from nano- and submicron titanium carbide powders, it was found that the strength have close values. Ultimate bending strength are in the range of 2.6 – 18.1 MPa. As the porosity of the material increases, the tensile strength decreases. Fracture is brittle. In the fracture of materials obtained from titanium carbide nanopowder, destruction is observed both along the body and along the grain boundaries regardless of the sintering temperature. In materials obtained by sintering submicron titanium carbide powder at 1500 °C, the destruction occurs predominantly along the body of the grains. It has been found that under the same sintering conditions, the density of the porous material made of titanium carbide nanopowder is higher than that of the material made of submicron powder.

Study on Strength Characteristics of Granular Materials

Crushing strength of granular material plays vital role in major civil engineering structures like offshore constructions, pile driving, mining under the high stresses. Determining the crushing strength of granular materials and also experimental results get influenced by its size, shape of grains, density, load application, strain rate, and its aspect ratio etc. So, crushing strength value differs from material to material. With this in view, here an attempt is made to determine the crushing strength for different granular materials like Natural River sand, Ennore sand, Glass beads and Geopolymer fly ash sand with specially fabricated mold. All materials are tested and characterized for index and engineering properties and also determined crushing strength by strain controlled digital load frame for different aspect ratios. Similar crushing strength values obtained for 12M Geo-polymer sand compared to other granular materials hence Geopolymer sand as an alternative material to natural river sand. Experimental results are tabulated in the paper.

Analisis Geoteknik Ditinjau dari Karakteristik Kuat Geser Material Longsoran

This research aims to analyze geotechnical aspects in the context of slope stability and soil landslides. The main focus of this research is on the shear strength characteristics of materials, which are a key factor in predicting the potential for landslides. The methods used in this research involve field geotechnical data collection, laboratory testing to determine geotechnical parameters, and numerical modeling to analyze slope stability. The research results indicate that the shear strength of landslide materials is a crucial factor in evaluating slope stability. Variations in geotechnical properties of materials, such as water content, soil texture, and density, have a significant impact on shear strength and the potential for landslides. Additionally, numerical analysis shows that environmental factors, such as rainfall and human activities, can also influence slope stability. This research provides a better understanding of the relationship between shear strength characteristics of materials and slope stability, serving as a basis for the development of landslide risk mitigation strategies. This has important implications for disaster management and safe land use planning in landslide-prone areas.

ANN-based structure peciliaties evaluation of polymer composite reinforced with unidirectional carbon fiber

At the moment, there is a growing interest in composite materials with matrices based on thermoplastic polymers; these materials are superior to traditional carbon fiber plastics due to higher fracture toughness and impact strength, low smoke generation during combustion, and high thermal and chemical resistance. The deformation behavior of such composite materials due to the high plastic deformation of the matrix differs from the behavior of traditional composites, which must be considered when performing calculations. In our study, as a model object, the features of the microstructure of single carbon thread impregnated with polysulfone were studied in order to evaluate the distribution of misorientation angles of elementary fibers, the degree of their damage, the thickness of the polymer matrix interlayers between elementary fibers in threads impregnated with more viscous thermoplastic binders. Statistical analysis of a large array of micrographs was carried out using specially developed algorithms for computer processing of electron microscopic images of a composite material. Algorithms for processing arrays of images using machine vision algorithms are proposed. Based on the analysis of the data array, the distributions of carbon fibers impregnated with polysulfone were plotted over the misorientation angle of the filaments and over the interfilament distance in the longitudinal and cross sections of the fiber. Using the machine learning method, an algorithm for detecting violations of the filament structure was implemented. The data obtained can be used to refine the calculations of the strength and deformation characteristics of composite materials with thermoplastic matrices.

Mechanical and antibacterial properties of hybrid polymers composite reinforcement for biomedical applications

This research investigates the biocompatibility, mechanical strength, and tribological properties of a hybrid composite material composed of high-density polyethylene (HDPE), hydroxyapatite (HAp), and titanium dioxide nanoparticles (Ti ). The study explores the microstructural characteristics of the composite material using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). Samples of HDPE-30%HAp with varying concentrations of Ti (5, 10, 15, and 20%) were prepared and extruded using a twin-screw machine. The hybrid composite materials underwent mechanical tests (tensile, flexural, and hardness), tribological tests (friction and wear rate), and antibacterial tests (resistance to Escherichia coli and Staphylococcus aureus bacteria). The results indicate that the optimal hybrid composite sample was HDPE-30%HAP-10% Ti , which demonstrated excellent mechanical properties (maximum tensile strength of 25.93 MPa and young modulus of 480 MPa) and a low coefficient of friction (COF∼ 0.07) while achieving high wear resistance (wear rate in the order of 1m ). The study shows that the improvement in mechanical properties results in a corresponding improvement in tribological properties. The antibacterial tests revealed that the hybrid composite material exhibited resistance to E. coli and S. aureus bacteria. The findings of this study suggest that the HDPE-30%HAP-10% Ti composite is a promising material for use in biomedical applications due to its excellent biocompatibility and desirable mechanical and tribological properties. The study demonstrates the potential of reinforced hybrid composite materials in overcoming the disadvantages of monolithic and hybrid micro-composites and highlights the importance of investigating the microstructural, tribological, and mechanical strength characteristics of composite materials for biomedical applications.

Damage constitutive model of uniaxially compressed coal material considering energy dissipation

Coal plays a dominant role in China's energy production and consumption, which also serves as the cornerstone for energy security. The constitutive relationship of coal material is of great significance for the quantitative characterization and evaluation of mechanical properties of isolated coal pillars. From an energy perspective, coal failure is driven by energy, and the energy-based damage characterization provides a basis for the establishment of constitutive model. In this study, since the constitutive model based on the classical Lemaitre's hypothesis shows a significant error in presenting the nonlinear constitutive relationship of coal material, a correction coefficient considering the compaction effect of coal material is first introduced. Then, a novel damage constitutive model that can accurately describe the overall compression state of coal material is constructed. Finally, the theoretical model is compared with exiting models using the experimental data of five types of coal material from different mines. The results show that the evolution of energy dissipation damage variable is highly consistent with that of stress–strain relations. The established constitutive model considering energy dissipation and compaction effect can more accurately describe the nonlinear strength and deformation characteristics of coal material than the classical and existing models. Notably, this new model can be effectively extended to the single cyclic compression conditions to reproduce the loading-unloading-reloading process of coal material.

A Method for Plotting Failure Envelopes of Unidirectional Polymer Composite Materials under Different Strain Rates

This article emphasizes the significance of investigating the nonlinear behavior and strength characteristics of polymer composite materials under various strain rates. The study utilizes test results of a unidirectional (UD) composite material subjected to compression at different angles relative to the reinforcement direction, using quasi-static, static, and dynamic strain rates. The analysis focused on a UD layer experiencing compressive stresses perpendicular to the fiber reinforcement and in-plane shear stresses. A novel model is presented, enabling the calculation and prediction of the strength of a UD composite under uniaxial loading at different angles to the fiber direction, considering various strain rates. The developed model facilitates the derivation of equations for the failure envelopes of UD Carbon Fiber-Reinforced Polymers (CFRPs) under quasi-static, static, and dynamic loading conditions. To construct the failure envelopes of CFRPs, it is necessary to acquire experimentally determined values of tensile and compressive strength in the direction perpendicular to the reinforcement, as well as the ultimate strength in uniaxial compression of a specimen with reinforcement at a 45° angle to the loading axis. The failure envelopes generated using the proposed model exhibit excellent agreement with experimental data, with coefficients of determination ranging from 0.864 to 0.957, depending on the deformation rate. Consequently, the developed model holds promise for predicting the strength of other UD polymer composite materials.

Fluidity and Strength of Loess-Based Quick Consolidated Backfill Material with One High-Water Content.

To study the flow and strength characteristics of loess-based backfill materials, orthogonal tests were used to design a cemented backfill material combining loess, high-water content materials, cement, and fly ash. By using the range, analysis of variance, and multi-variate regression analysis, influences of four key factors on the initial setting time, diffusivity, compressive strength, and shear strength of the backfill material were investigated. These four factors included the mass concentration of loess water (A), the content of high-water content materials (B), cement content (C), and content of fly ash (D). The results showed that the initial setting time, diffusivity, compressive strength, and shear strength of the backfill material were 13~33 min, 400~580 mm, 0.917-3.605 MPa, and 0.360-0.722 MPa, respectively, all distributed in wide ranges. For the initial setting time, the four factors were listed in descending order as A > D > B > C according to their influences; for diffusivity, the four factors were listed as A > B > C > D; for the compressive strength, the four factors were ranked as A > C > D > B; for the shear strength, the four factors were ranked such that A > C > D > B. With regard to the comprehensive index, the four factors were such that A > B > D > C. That is, the factors were listed in descending order as the mass concentration of loess water, cement content, the content of fly ash, and content of high-water content materials according to their significance in influencing characteristics of the loess-based backfill material. Comprehensive analysis indicated that the fluidity of the material was mainly influenced by the mass concentration of loess water, and the two were negatively correlated. The hydro-consolidation effect of materials with high-water contents accelerated material solidification. The strength of the backfill material was mainly influenced by the cement content while only slightly affected by contents of other materials. In this way, a prediction model for characteristic parameters, namely, fluidity and strength, of the loess-based backfill material under the action of various factors was established.

Experimental Study on the Reciprocating Shear Characteristics and Strength Deterioration of Argillaceous Siltstone Rockfill Materials

The reciprocating shear mechanical properties and strength deterioration mechanisms of rockfill materials are of great research significance for high-fill slope stability analysis. To study the shear strength characteristics of argillaceous siltstone rockfill materials with different fabric characteristics under reciprocating shear loading, we analyzed the shear strength, hysteresis loop area, damping ratio, shear strength parameter, and shear stiffness of coarse-grained soils with different coarse grain contents using a coarse-grained soil direct shear testing machine capable of reciprocating shear and revealed their strength deterioration mechanism. The test results show that the shear strength of argillaceous siltstone rockfill materials is significantly affected by the coarse grain content and the number of reciprocating shears. Specifically, the shear strength increases with the coarse grain content and decreases with the number of reciprocating shears. The hysteresis loop area is positively correlated with the coarse grain content and negatively correlated with the number of reciprocating shears. The damping ratio is not related to the coarse grain content but tends to decrease with the number of reciprocating shears. Soil cohesion and the internal friction angle increase with the coarse grain content and decrease with the number of reciprocating shears. The soil failure shear stiffness is linearly correlated with the coarse grain content, and the normalized shear stiffness is logarithmically related to the number of reciprocating shears. According to these relationships, an empirical formula for the shear stiffness of argillaceous siltstone rockfill materials under different coarse grain contents and different numbers of reciprocating shears can be established to provide a basis for analyzing rockfill stability.

Study on Filling Material Strength and Dam Failure Characteristics of Loess Dam

In the Loess Plateau region, loess, as a widely distributed building material, is often used as a filling material for dams. When the water level reaches a certain height, the body of a dam is prone to shear failure due to the penetration of water. The change in the shear performance of local loess filler can affect the overall strength of loess dams. Therefore, the filler of a loess dam is selected to study the shear performance. The progressive failure process of a loess dam is simulated. The shear failure characteristics of loess filler under the influence of water content, confining pressure, and dry density were explored. The characteristics of the shear failure of a loess dam were analyzed. The remolded loess is prone to shear expansion failure under low confining pressure, low water content, and high dry density, and is prone to shear shrinkage failure under high confining pressure, high water content, and low dry density. When the water content is constant, the cohesion increases with the increase in dry density. When the dry density is constant, the internal friction angle generally increases with the increase in water content. However, when the dry density is high, the permeability of the remolded loess is weakened, resulting in uneven water distribution under a low water content, which affects the test results. The failure process of the loess dam is a progressive shear failure, which is affected by the water level and water pressure, and is destroyed under the action of pore water pressure and water body lateral pressure.

The Effect of Severe Plastic Deformation on the Microstructure and Mechanical Properties of Composite from 5056 and 1580 Aluminum Alloys Produced with Wire Arc Additive Manufacturing

In this study, a composite with alternate layers of 5056 and 1580 alloys was manufactured with wire arc additive manufacturing technology. It is shown that increased strength characteristics of composite material can be obtained with deformation treatment using a high-pressure torsion (HPT) technique. The microstructure and mechanical properties of the HPT-processed material in different structural states were investigated. The HPT-processed material exhibits a high value of ultimate tensile strength (~770 MPa) but low ductility. Short-term annealing at 250 °C and additional deformation with HPT to 0.25 of revolution at room temperature resulted in a slight decrease in the material’s strength to ~700 MPa but provided ductility of ∼9%. Physical mechanisms to improve plasticity in correlation with microstructure evolution are discussed.