Strength Properties Research Articles

Optimization of strength properties of bamboo mesoparticles reinforced polyamide 6 using Box–Behnken approach

Bamboo mesoparticles were used as a viable alternative reinforcement in matrix polymers to produce eco-friendly products, and the alternative mesoparticles were used as reinforcement for cheaper processing methods and comparable mechanical properties as nanoparticle. The main factors that influence the mechanical behavior of natural composites are fiber size, fiber loading, and chemical treatment. This study optimized the blending parameters of bamboo mesoparticle/polyamide 6 composites through response surface methodology based on Box–Behnken design. The predicted strength values for these composites as a function of independent variables were obtained from the analysis of variance statistical approach. The analysis of the results showed that fiber size, fiber loading, and alkali concentration variables significantly in quadratic model terms. This model was used to determine the maximum strength, and it was closely in agreement with the experimental finding with the value of R2 = 0.9385. The optimum conditions for tensile strength were identified as fiber size 1 µm, NaOH of 2 wt.%, and fiber loading of 18 wt.%. The optimum conditions for flexural strength were identified as NaOH of 2 wt.%, particle loading of 13 wt.%, and particle size of 0.46 µm.

PHYSICAL-MECHANICAL AND DEGRADATION PROPERTIES OF THERMOPLASTIC STARCH DEPENDING ON THE COMPOSITION OF THE STRUCTURE-FORMING MODIFYING ADDITIVE

The composition of thermoplastic starch (TPS) was prepared using glycerol as a plasticizer, lactic acid and its binary mixture with stearic acid. A number of component concentrations and thermo-mechanical technological parameters were varied during starch processing and formation of film-forming compositions. Physical-mechanical tests of TPS film samples were carried out, and the strength and elasticity properties were determined depending on the concentration of plasticizer and structure-forming additives. The effect of UV irradiation on the degradability of TPS compositions and TPS film samples with synthetic polymer - polyethylene was studied. The optimal composition, loss of strength and elasticity in the range of 80–100% after 90 days of aging in a climate chamber were determined. Mass spectrometric study of TPS films before and after UV irradiation confirmed the influence of structure-forming additives of stearic and lactic acids on the degradability of TPS compositions. The obtained results indicate the possibility of forming plastic materials with the ability of rapid degradation under environmental conditions.

Selection of Processing Methods and Parameters for Composite Inserts in Window Profiles with Regard to the Strength of Their Welds.

In the study of structural materials, the analysis of fracture and deformation resistance plays an important role, particularly in materials widely used in the construction industry, such as poly(vinyl chloride) (PVC). PVC is a popular material used, among others, in the manufacture of window profiles, doors, pipes, and many other structural components. The aim of this research was to define the influence of the degree of milling of the glass-fibre-reinforced composite on the strength of the window frame welds, and in the next step, to propose new welding parameters to obtain sufficient strength properties that allow reducing the cost of the technological welding operation. During the tests, it was found that the average failure load of the composite samples was highest at a milling depth of 1 mm and lowest at 6 mm. Up to a depth of 1 mm, the values of destructive loads show an increasing trend, while above this depth, a decreasing trend. A clear reduction in strength was observed when milling to a depth of 1.5 mm, which is related to material discontinuity and the lack of a visible weld joint caused by milling too deep. The differences in average failure loads between the samples of 0 mm, 0.5 mm, and 1 mm milling are minimal.

The Influence of the Addition of Microsilica and Fly Ash on the Properties of Ultra-High-Performance Concretes

The paper presents experimental studies on the influence of a simultaneous, appropriately proportioned combination of microsilica and fly ash additives on the physical and mechanical properties of ultra-high-performance concretes (UHPCs). Concrete mixtures with the addition of microsilica in the amount of 6.7–14.7% and fly ash in the amount of 8.3–26.7% were analyzed, assuming a constant content of cement, water and superplasticizer. Experimental studies were carried out regarding the consistency of the fresh concrete mixtures and on the compressive strength, flexural strength, tensile splitting strength, secant modulus of elasticity, depth of penetration of water under pressure into hardened concrete and water absorption. The analysis of mechanical properties was carried out during a long maturation period from 2 to 90 days. Additionally, the influence of the cost of component materials on the final cost of concrete was taken into account. The test results indicate the effectiveness of the use of microsilica and fly ash additives in ultra-high-performance concretes and possible directions for optimizing their proportions in order to achieve the intended physical and mechanical properties. The best strength properties were obtained for concrete containing 16.7% fly ash and 13.3% microsilica. The highest resistance to water penetration and absorption under pressure was characterized by concretes containing an increased content of microsilica up to 14.7%.

Устройство для интенсификации предварительного разупрочнения мёрзлых вскрышных пород на карьерах криолитозоны

The main challenges in mining frozen grounds in winter time are related to the topmost layer, which softening can provide optimal conditions for its removal. The article describes the developed patented device, which can be used in the openpit mining of mineral deposits in the permafrost zone, providing intensification of preliminary blastless softening of frozen overburden using surface-active substances (surfactants). It is emphasized that the technical task of the device is to maintain a constant level of solution in the boreholes without its overflow, ensuring continuous penetration of the surfactant solution into the cracks and pores of the ground mass due to the hydrostatic pressure of the surfactant solution itself. For this purpose, the device is fitted with a perforated dispenser to ensure a uniform, continuous supply of the surfactant solution. A dedicated hole or valve should be provided in the upper part of the shell to balance the pressure inside the tank with atmospheric pressure, and its lower part is covered with drilling fines to provide its vertical stability. An insufficient degree of implementing the surfactantbased methods of rock softening is noted, as well as the fact that the proposed device will cause a decrease in their strength and deformation properties and will allow, within certain limits, to control the state and properties of the mined rock mass in open-pit mines in the northern regions of the Russian Federation.

Using Food Industry Byproduct to Stabilize an Expansive Clay

The process of purifying agricultural products, at various food processing plants, generates waste materials that consist of precipitated calcium carbonate, organic debris, and trace amounts of soil and agricultural contaminants. A specific food-processing waste, hereafter referred to as a food industry byproduct, FIBP, is typically stockpiled on land adjacent to the corresponding food processing facilities due to its large volume and chemical composition. The FIBP also contains commercially available unspent lime products, which makes its reuse viable in various applications. An example is construction applications where an organic content of up to 5% by weight is allowed, such as treating expansive clays. Traditionally, lime stabilization has been used for improving the properties of expansive clays, where ground improvement methods are necessary for a large area. However, the process of producing lime is resource- and energy-intensive as it includes crushing and heating limestone in kilns to extract lime. Therefore, one specific doubly sustainable application is the treatment of expansive clays using the FIBP instead of lime. The main application tested here is the treatment of expansive clayey soils underneath a stretch of State Highway 95 near Marsing, ID. Other potential applications are in road and embankment construction. To evaluate the potential of expansive clay stabilization utilizing the FIBP, a series of geotechnical and environmental laboratory testing were conducted to measure the engineering properties (e.g., swell potential, permeability, and strength properties) of expansive clay amended with FIBP. Preliminary testing on blends with an expansive clay suggests benefits such as decreased swelling potential, increased density, and leachate immobilization.

INVESTIGATING THE CRACK PROPAGATION RESISTANCE OF NANO CONCRETE THROUGH FRACTURE MECHANICS

In the concrete treatments, small cracks are beginning developing inside. As a result of temperature and stress variations during extraction, the fragments will enlarge and unite to form some noticeable cracks. Concrete constructions may suddenly shatter as a result of cracks spreading. The study focuses consideration of the inspiration of additives on the properties of fracture in high-performance concrete with additives (HPCA) as a foundation for the effective application of building structures. Compared to traditional concrete, HPCA has better mechanical qualities and durability. The highly responsive nanoparticles significantly improved concrete performance. Portland cement has been replaced with nanoparticles at different percentages of weight to create HPCA mixtures. The impact of nano silica (nS) and nano alumina (nA) on the appearance of fracture and crack extension resistance of HPC during the process of entire fracture will be assessed in this research. Based on the softening laws and outcomes of the bending test of three-point of concrete material along with grooves, the resistance of crack extension of HPCA was determined. The crack mouth opening displacement versus load relationship curves (P-CMOD) represent the ultimate result. Compressive strength and additional mechanical properties have been determined within the model. Ultimately, the P-CMOD curves are used to analyse and compute the fracture parameters and features of HPCA utilizing nano particles.

Performance research and structure optimization of quartz-covered alumina high-strength wear-resistant yarn

Improved abrasion resistance and shear performance of alumina fiber yarns is crucial to the weaving process. Herein, a series of novel SiO2@Al2O3 single-layer and double-layer covered yarns were prepared by winding 48 tex quartz yarn on the outer layer of 120–600 tex alumina yarn with wrapping twist of 50–500 twists/m. Wear resistance, shear force, and tensile fracture properties of the covered yarn were tested and analyzed. Wrapping twist ranges from 50 to 400 twists/m, with increased wrapping twist improving the SiO2@Al2O3 covered yarn's breaking strength, shear force, and wear resistance. As wrapping twist ranges from 400 to 500 twists/m, uneven winding and wear of quartz yarn weaken the breaking strength, wear resistance, and shear properties of SiO2@Al2O3 covered yarn. SiO2@Al2O3 double-layer covered yarn exhibits superior shear force, wear resistance, and tensile breaking strength compared with its single-layer counterpart. In comparison with the initial alumina yarn, wear resistance of SiO2@Al2O3 covered yarn improves by 50%, whereas the maximum shear strength and tensile breaking strength increase by 125% and 15%, respectively. High-strength, wear-resistant SiO2@Al2O3 covered yarn is suitable for alumina fabrics and braid structures, and is expected to be widely used in aerospace and the high-temperature insulation industry.

Justification of Progressive Parameters of The Sides of Copper Ore Quarries

A methodological approach to the justification of steep (progressive) sides of copper ore quarries is presented on the basis of complex geomechanical studies of rocks directly in the instrument arrays using cores obtained from specially drilled engineering-geological wells to determine the size of structural blocks, the quality index of the array and the structural attenuation coefficient and parallel laboratory study of the strength and physical properties of rocks. The assessment of the stability of the sides of the quarry by various calculation methods made it possible to verify their reliability and good convergence. Rather steep (progressive) parameters of the sides of the quarry are recommended, at their height of 300 m, their angles of inclination range from 46° to 52° with a coefficient of stability ranging from 1.19 to 1.37. The implementation of geotechnological studies based on rating classifications allows us to obtain reliable strength characteristics of rocks necessary for numerical modeling of geomechanical processes. The stability of the sides of the quarry was assessed by various calculation methods, which made it possible to verify their reliability and good convergence of numerical- analytical and rating calculation systems, which are carried out using special programs.

A FINITE ELEMENT MODEL FOR CALCULATING A NON-THIN ORTHOTROPIC CYLINDRICAL SHELL, TAKING INTO ACCOUNT THE INDUCED INHOMOGENEITY

The formulation of a model for the deformation and strength calculation of an open cylindrical shell of circular shape rigidly pinched along contour planes formed by generators is considered. The ratios of the geometric parameters of the shell differ significantly from thin-walled structures, to which traditional technical hypotheses could be applied. The formulation of a mathematical model defining the stress-strain states of a thick-walled structure was carried out within the framework of a nonlinear three-dimensional theory. The peculiarity of the developed model was that orthotropic composites were adopted as the structural materials of the shell, the deformation and strength properties of which manifest themselves in different ways in accordance with the types of stress states being realized. The manifestation of such mechanical properties of materials is interpreted as induced heterogeneity, which significantly complicates the methodology for calculating spatial structures. Due to the specified features of the research object, isoparametric finite elements of a three-dimensional tetrahedral shape, the nodes of which had three degrees of freedom, were used to develop a computational model. In order to adequately account for the stiffness properties of orthotropic composites exhibiting induced heterogeneity, the basis of the determining relationships for them was the deformation potential formulated in the normalized stress tensor space associated with the main axes of orthotropy of materials. Due to the nonlinearity of the problem under consideration, the process of solving it was based on the method of variable elasticity parameters. As a result of the implementation of the computational model, comprehensive information was obtained on the stresses, deformations and displacements of the shell, the main of which are presented in the text of the article with the addition of their analysis.

Multiscale Structural Strong yet Tough Triboelectric Materials Enabled by In Situ Microphase Separation

AbstractLightweight green polymer materials with exceptional toughness, high strength, and excellent ductility represent ideal candidates for enabling next‐generation sustainable flexible electronics. However, the conflicting properties of material strength and toughness present a significant challenge in achieving an optimal combination of both attributes. In this study, a strong yet tough polymeric triboelectric material is prepared by constructing a multiscale reinforced network based on a nonsolvent‐induced microphase separation strategy. The synergistic enhancement of strength and toughness is achieved by reinforcing non‐covalent interactions within the polymer and constructing nanofibrous networks. The resulting triboelectric materials exhibited remarkable fracture toughness (78.6 MJ m−3), high tensile strength (42.5 MPa), an improvement in triboelectric output (71%), and promising recyclability. The integrated triboelectric wearable sensor maintained robust output signals. This study provides a novel solution for coordinating the conflicts between strength and toughness in heterogeneous polymer materials, showing significant potential in expanding their applications in flexible electronics and self‐powered sensing technologies.

Analysis of existing studies on wood under impact and ballistic loads

Wood is one of the oldest building materials. However, with the advent of the industrial revolution, metal and reinforced concrete structures have almost completely displaced wood from the market of basic building materials. At the same time, wood is widely used in the manufacture of furniture, decoration, floors, auxiliary structures, etc., and this applies to all spheres of human life and everyday life. A separate niche is occupied by wood asa material for fortifications, as the most accessible. Studies of the ballistic characteristics of wood are most relevant in forensics, due to the fact that bulletsfired in urban conditions very often hit wooden objects [1].The war unleashed by the Russian Federation in Ukraine forces engineers to look for the most rational materials for the construction of buildings forboth civilian and military purposes. And in this case, wood can be a competitive material along with concrete and steel, given the fairly good ability of woodto absorb energy. Certain types of wood are considered impact-resistant, so beech is used for the manufacture of hammer heads [3]. In addition to solidwood, there are quite a large number of wood-based materials, such as: glued wood, cross-laminated timber, glued veneer lumber and many others.These materials are already widely used in the construction of both low-rise and multi-story buildings. The properties of these materials for the perceptionof vertical and horizontal loads have been actively studied since the 1960s. However, the characteristics of impact strength and ballistic properties ofthese materials have hardly been studied. This paper considers the state of modern research on the ballistic properties of wood and materials based on it with the prospect of further research and use in engineering protection structures.

High-Temperature Polymer Components Reimagined: Scalable Syntheses and de novo Routes to Structurally Versatile Precursors

Developing efficient and scalable synthetic protocols for key polymer precursors is crucial to advancing high-performance materials designed to withstand severe thermal environments. In this article, we report on the development of solid, high-yield methods for preparing structurally diverse building blocks, including s-triazine derivatives, phenyl-borosilane alkynyl oligomers, phthalonitrile-based monomers, and novel diamine curing agents on multi-gram to multi-hundred-gram scales. These carefully optimized procedures use readily available starting materials, mild conditions, and well-known synthetic transformations, thus addressing the longstanding challenges associated with their practical upscaling. The resulting library of monomers and oligomers offers a broad range of reactive functional groups (e.g., nitriles, alkynes, borosilane motifs), enabling future combinatorial-like strategies for the formation of advanced co-polymers with enhanced thermal stability, mechanical strength, and tunable properties suitable for high-temperature applications.

Influence of Structural Optimization on the Physical Properties of an Innovative FDM 3D Printed Thermal Barrier.

This article describes an innovative thermal insulation barrier in the form of a sandwich panel manufactured using 3D FDM printing technology. The internal structure (core structure) of the barrier is based on the Kelvin foam model. This paper presents the influence of the parameters (the height h and the porosity P of a single core cell) of the barrier on its properties (thermal conductivity, thermal resistance, compressive strength, and quasi-static indentation strength). The dominant influence of the porosity of the structure on the determined physical properties of the fabricated samples was demonstrated. The best insulation results were obtained for single-layer composites with a cell height of 4 mm and a porosity of 90%, where the thermal conductivity coefficient was 0.038 W/(m·K) and the thermal resistance 0.537 (m2·K)/W. In contrast, the best compressive strength properties were obtained for the 50% porosity samples and amounted to about 350 MPa, while the moduli for the 90% porosity samples were 14 times lower and amounted to about 26 MPa. The porosity (P) of the composite structure also had a significant effect on the punch shear strength of the samples produced, and the values obtained for the 90% porosity samples did not exceed 1 MPa. In conclusion, the test showed that the resulting 3D cellular composites offer an innovative and environmentally friendly approach to thermal insulation.

Study on properties of natural latex foam composites modified by corn straw‐derived biomass fiber

AbstractReinforcing fillers play a pivotal role in achieving superior performance of latex foam materials. The corn stalk, as an agricultural by‐product, possesses the advantages of abundant availability, renewability, and environmental friendliness. In this study, natural rubber latex foam (NRLF) was prepared using the Dunlop method with the addition of corn stalk (CS) as a reinforcing agent. To further enhance the adhesion between the biomass fiber and matrix, alkali‐treated CS/natural rubber latex foam (ACS/ NRLF) was prepared by modifying the CS with a 6% sodium hydroxide solution. The effects of different amounts of CS and ACS on the properties of the composites were investigated. The results demonstrate that loading 5phr of ACS significantly improves mechanical properties such as tensile strength, compressive capacity, recovery rate, and other properties in ACS/NRLF materials. Furthermore, surface treatment of the fiber is shown to greatly enhance material performance. This indicates that CS has great potential in the application of latex foam materials.

The Use of Recycled Ceramics and Ash from Municipal Sewage Sludge as Concrete Fillers

The main aim of the research was to evaluate the feasibility of using recycled ceramics and ash from municipal sewage sludge as concrete fillers. As part of the study, standard cylindrical and cubic samples were investigated. The samples consisted of waste ceramic aggregate fractions 0–4 mm and 4–8 mm, which were sourced from used products manufactured by a sanitary fittings factory, as well as ash from one of the Polish sewage treatment plants. The chemical composition and morphology of recycled materials used to produce concrete were examined. The research itself focused on determining the strength properties of the produced composites under both normal conditions and after initial heat treatment. Microstructural tests of the produced composites were also carried out. The results demonstrated that selected recycled materials can successfully replace materials previously used in concrete production. The obtained strength results do not differ significantly from the strength of concrete made of traditional materials. Research has confirmed the possibility of using waste materials as concrete fillers.

Prediction Rock Strength Properties for Southern Iraqi Field. Application of Petrophysical and Mechanical Properties Relationship, Using Wireline Log Data

Rock Strength Properties (Internal Friction Angle

Shape Optimization and Experimental Investigation of Glue-Laminated Timber Beams.

This study investigated the optimal shape of glue-laminated timber beams using an analytical model of a slender beam, taking into account the anisotropy of its strength properties as well as boundary conditions at the oblique bottom face of the beam. A control theory problem was formulated in order to optimize the shape of the modeled beam. Two optimization tasks were considered: minimizing material usage (Vmin) for a fixed load-carrying capacity (LCC) of the beam and maximizing load-bearing capacity (Qmax) for a given volume of the beam. The optimal solution was found using Pontryagin's maximum principle (PMP). Optimal shapes were determined using Dircol v. 2.1 software and then adjusted according to a 3D finite element analysis (FEA) performed in Abaqus. The final shapes obtained through this procedure were used in the CNC-based production of three types of nine beams: three reference rectangular beams, three Vmin beams, and three Qmax beams. All specimens were subjected to a four-point bending test. The experimental results were contrasted with theoretical assumptions. Optimization reduced material usage by ca. 12.9% while preserving approximately the same LCC. The maximization of LCC was found to be rather unsuccessful due to the significant dependence of the beams' response on the highly variable mechanical properties of GLT.

Preparation and Characterization of Melamine Aniline Formaldehyde-Organo Clay Nanocomposite Foams (MAFOCF) as a Novel Thermal Insulation Material.

The main purpose of this study is to prepare a melamine aniline formaldehyde foam, an MAF copolymer, with lower water sensitivity and non-flammability properties obtained by the condensation reaction of melamine, aniline, and formaldehyde. In addition, the preparation of MAFF composites with organoclay reinforcement was determined as a secondary target in order to obtain better mechanical strength, heat, and sound insulation properties. For the synthesis of foams, the microwave irradiation technique, which offers advantages such as faster reactions, high yields and purities, and reduced curing times, was used together with the heating technique and the effect of organoclay content on the structural and textural properties of foams and both heat insulation and mechanical stability was investigated. Virgin melamine formaldehyde foam, MFF, melamine aniline formaldehyde foam, MAFFF, and melamine aniline formaldehyde-organoclay nanocomposite foams prepared with various organoclay contents, MAFOCFs, were characterized by HRTEM, FTIR, SEM, and XRD techniques. From spectroscopic and microscopic analyses, it was observed that organoclay flakes could be exfoliated without much change in the resin matrix with increasing clay content. In addition, it was determined that aniline formaldehyde, which is thought to enter the main polymer network as a bridge, caused textural changes in the polymeric matrix, and organoclay reinforcement also affected these changes. Although the highest compressive strength was obtained in MAFOCF5 foam with high organoclay content (0.40 MPa), it was determined that the compressive strengths in the nanocomposites were generally quite high despite their low bulk densities. In the prepared nanocomposite with 0.30% organoclay content (MAFOCF2), 0.33 MPa compressive strength and 0.051 thermal conductivity coefficient were measured. For virgin polymers and composites, bulk density, thermal conductivity, and compressive strength values were determined in the order of magnitude as MFF > MAFOCF1 > MAFOCF5 > MAFOCF6 > MAFF > MAFOCF3 > MAFOCF2 > MAFOCF4; MFF > MAFF > MAFOCF6 > MAFOCF5 > MAFOCF1 > MAFOCF4 > MAFOCF3 > MAFOCF2 and MAFOCF5 > MAFOCF4 > MAFOCF2 > MAFF > MAFOCF6 > MFF > MAFOCF1 > MAFOCF3. As a result, both compressive strength and thermal conductivity values indicate that nanocomposite foam with 0.20 wt% organoclay content can be a promising new insulation material.

Valorization of Recycled Aggregate and Copper Slag for Sustainable Concrete Mixtures: Mechanical, Physical, and Environmental Performance

The increasing environmental impacts caused by the high demand for concrete production have underscored the need for sustainable alternatives in the design of eco-concrete mixtures. Additionally, important industries, such as construction and mining, generate massive amounts of waste/by-products that could be repurposed towards sustainability. Consequently, this study investigates the valorization of copper slag (CS), a by-product of the mining industry as a supplementary cementitious material (SCM), and concrete as recycled coarse aggregate (RCA), derived from construction and demolition waste, as partial substitutes for Ordinary Portland Cement (OPC) and natural coarse aggregate (NCA), respectively. Eco-concrete mixtures were designed with varying replacement levels: 15% for CS, and 0%, 20%, 50%, and 100% for RCA. The mechanical properties (compressive, indirect tensile, and flexural strengths), permeability characteristics (porosity and capillary suction), and environmental impacts (carbon footprint) of these mixtures were evaluated. The results showed that the use of CS and of increasing proportions of RCA led to a monotonic loss in each of the concretes’ mechanical strength properties at 7, 28 and 90 days of curing. However, at extended ages (180 days of curing), the concrete mixtures with CS and only NCA presented an average compressive strength 1.2% higher than that of the reference concrete (mixture with only OPC and natural aggregate). Additionally, the concrete mixture with CS and 20% RCA achieved 3.2% and 5.8% higher average values than the reference concrete in terms of its indirect tensile strength and flexural strength, respectively. Finally, a cradle-to-gate life cycle assessment (LCA) analysis was implemented, whose results showed that the greatest effect on reducing the carbon emission impacts occurred due to the substitution of OPC with CS, which confirmed that the adequate technical performances of some of the concrete mixtures developed in this study are positively complemented with reduced environmental impacts. Moreover, this study presents a viable approach to minimizing resource consumption and waste generation, contributing to the advancement of eco-friendly construction materials, which aligns with the sustainable development goals.