Strength Of Materials Research Articles

Evaluation of Mechanical Properties of Sabai Grass (Eulaliopsis binata) Fibers and Epoxy Resin Composite Laminates Using Fly Ash as Filler Material

The integration of sabai grass fibers and fly ash in epoxy resin combines the strengths of both materials for developing a tailor-made composite laminate that balances performance, sustainability, and cost-efficiency. This innovative blend of natural fibers and industrial waste promotes environmental conservation. The laminates produced could also be used in diverse industrial and structural applications. This study investigated the mechanical properties of composite laminates reinforced with sabai grass fibers, fly ash filler, and epoxy resin as the matrix. In this work, the hand lay-up method was used to fabricate composites with two stacking configurations ((0°/0°/0°/0°) and (0°/90°/90°/0°)) and filler contents of 1.5 wt.%, 3 wt.%, and 5 wt.%. Various weight fractions of fly ash filler and sabai grass fiber were integrated into the epoxy resin to evaluate their impact on tensile strength, flexural strength, and hardness. The experimental results indicate that adding fly ash significantly improves the composite’s hardness to 27 HV in the composites containing 5 wt.% filler, while sabai grass fibers contribute to enhanced tensile strength and flexural strength. The composites with (0°/0°/0°/0°) fibers and 5 wt.% filler showed a higher tensile strength of 63.5 MPa and flexural strength of 118.5 MPa. The fractured sample was analyzed with the help of FESEM images. The XRD analysis confirmed the presence of fly ash components suitable for forming a bond with epoxy. EDX was conducted to determine the elemental composition of the fly ash. FTIR analysis verified the removal of impurities such as dust, dirt, and lignin from the fiber surface following NaOH treatment.

Synergistic Chemical Modification and Physical Adsorption for the Efficient Curing of Soluble Phosphorus/Fluorine in Phosphogypsum

Phosphogypsum (PG), a by-product of phosphoric acid production, contains high levels of fluorine and phosphorus impurities, which negatively impact the strength and setting time of PG-based cement materials and pose environmental risks. This study explores a dual approach combining physical adsorption using zeolite powder and chemical modification with quicklime (CaO) to immobilize these impurities. The composition of 90 wt.% PG, 5 wt.% zeolite powder, and 5 wt.% quicklime reduces the soluble phosphorus to below the detection limits and significantly lowers the free water content in the PG. Through SEM, XRD, and FT-IR analyses, it was found that zeolite powder adsorbs fluorine and phosphorus through encapsulation, while quicklime chemically reacts to form insoluble calcium phosphate and calcium fluoride. This transformation decreases the solubility, mitigating potential environmental contamination. The combination of physical adsorption and chemical conversion provides a sustainable strategy to reduce environmental hazards and enhance PG’s suitability for cement-based materials. The findings from this research offer a promising pathway for the sustainable utilization of PG, providing a mechanism for its safe incorporation into building materials, while addressing both environmental and material performance concerns.

Analysis on sensitivity and imperfect interfaces on the propagation of inter-facial anti-plane waves on the finely coated piezomagnetic reinforced composite structure

Abstract Surface acoustic waves are pivotal in modern technology due to their exceptional sensitivity and adaptability. The motivation for this study stems from the need to enhance the efficiency of surface wave sensors by advancing mass loading techniques and addressing the imperfections that can alter the magneto-mechanical properties, velocities, and propagation behavior of anti-plane waves in layered composite structures. The present work analyses the propagation behavior of Love-type and B-G-type waves in a piezomagnetic fiber-reinforced composite (PMFRC) structure underlying an Air medium (in Model-1) and under a coated thin filmed mass loading (in Model-2) in the presence of distinct inter-facial imperfections viz. Mechanically compliant magnetically weakly permeable (MCMWP), Mechanically compliant magnetically highly permeable (MCMHP), Low magnetic permeable (LMP), Magnetically grounded (MG), and welded. These inter-facial imperfections have been considered as five different submodels under both Model-1 and 2. At first, the micromechanical model of PMFRC has been developed, and closed-form expression for the material constants has been derived by harnessing the techniques of strength of materials and the rule of mixtures. Employing the suitable boundary conditions associated with distinct five inter-facial imperfections, velocity equations have been derived, validated, and graphically demonstrated for both magnetic cases (open (MO) and short (MS)) under various submodels of both models. Magneto-mechanical coupling, mass loading sensitivity, volume fraction, and imperfect interfaces affecting the phase velocity of Love-type and B-G type waves have been analyzed with a comparative approach under various models and submodels. The outcomes of the study can enhance detection capabilities in SAW devices, broadening their use in telecommunications, aerospace, and other industries.

Fatigue Strength Plateau Induced by Primary Alpha Phase Size in TC11 Alloy

Enhancing the fatigue strength of materials by increasing their tensile strength is generally considered as an effective strategy. This study observed a fatigue strength plateau in TC11 alloy: despite significant variations in tensile strength, the fatigue strength of TC11 alloy demonstrates remarkable stability. It is determined that this anomalous behavior is governed by a unique fatigue cracking mechanism associated with the primary α phase (αp) in dual‐phase titanium alloys due to the pilling‐up of dislocations and consequent cleavage (pillingup‐cleavage). Under this mechanism, the critical cracking stress is predominantly influenced by the pilling‐up distance of dislocations (reflected in the size of αp phase) and is relatively independent of the lattice frictional resistance (expressed in the nanoindentation hardness of αp phase). This leads to the occurrence of fatigue strength plateau in TC11 alloy in this study.

Empirical modeling of torsional strength in reinforced concrete beams using iterated local search with semantic cluster operator

AbstractThis study conducted a data‐based analysis on the impact of a feature and empirical modeling to increase the accuracy of analytical models related to torsional strength. The torsional strength data of 324 plain and reinforced concrete beams were collected from previous studies, which included data from specimens with various cross‐sectional sizes, material strengths, reinforcement ratios, and cover thicknesses. The data was clustered to analyze the effect of each feature, and the importance of each feature was derived using the Shapley additive explanations technique. An iterated local search using a semantic cluster operator was used to derive simple and highly accurate empirical models to predict the torsional strength. The proposed models predicted the ultimate strength by multiplying the contribution of concrete and transverse reinforcement, contrary to the current codes, and showed better accuracy than the existing models.

Recent progress in two-dimensional polymer materials: interfacial synthesis and applications

Abstract As a new two-dimensional polymer synthetic material, two-dimensional polymers (2DPs) not only have the advantages of high specific surface area and high transparency of two-dimensional materials, but also have the advantages of high mechanical strength and easy processing of polymer materials. Therefore, 2DPs are widely used and have become one of the indispensable materials today. However, there are still challenges in preparing 2DPs using traditional methods. Among the various synthesis strategies, the interfacial synthesis methods with the advantages of simple operation and high crystallinity have become typical method for preparing 2DPs. In this review, we first summarize the types of interface synthesis methods and the latest research progress. Secondly, the 2DPs applications in optoelectronic devices, membrane separation, sensor, electrical device and batteries, etc. are introduced. Finally, we summarize and prospect the existing challenges and future research directions based on the current research status of 2DPs.

Influence of strain rate and temperature on the thermomechanical behavior of flax fibers/Elium acrylic composite: Experimental characterization and modeling

AbstractThis study investigated the viscoelastic behavior of unidirectional flax fibers/Elium acrylic composite reinforced with multiwall carbon nanotubes (MWCNT), focusing on their sensitivity to strain rate and temperature. In parallel, a cyclic tensile analysis was performed to monitor damage mechanisms in the composite. The results revealed enhanced mechanical and viscoelastic properties with increasing load and frequency. However, a reduction of 7°C in the relaxation associated to the glass transition temperature (Tg) was observed, as measured by dynamic mechanical analysis, in composites containing MWCNT. The study also highlighted the strain rate and temperature dependence of the flax fibers/Elium acrylic composite. Damage analysis revealed that the inclusion of MWCNTs delayed the onset of damage in the composite, suggesting that MWCNTs enhance material strength and improve durability. Additionally, a new model, combining Richeton's approach with numerical modeling, showed good agreement with experimental data.Highlights MWCNTs improved fiber‐matrix interface in flax/Elium composites. Strain rate sensitivity, even with MWCNTs. MWCNTs raised storage modulus and shifted Tg to lower temperatures. MWCNTs delayed damage, enhancing composite durability. The new model provides a good prediction of elastic modulus.

Synergistic effects of fly ash and graphene oxide composites at high temperatures and prediction using ANN and RSM approach

Fly ash (FA) is a consequence of burning coal and is widely used in construction because of its pozzolanic qualities, which increase the strength and longevity of materials. Graphene oxide (GO) is a functionalized version of graphene with low electrical conductivity, high mechanical strength, and a large surface area. By examining the behavior of fly ash and GO composites at high temperatures, new materials with improved mechanical and functional qualities that are appropriate for a range of industrial uses can be created. By improving the material quality of cement and reducing material use while boosting durability, adding graphene oxide to cement offers an opportunity to drastically lower carbon emissions. However, the entire effect is dependent on the GO emissions, manufacturing procedures, and viability from an economic standpoint; to fully reap the benefits of this novel strategy for the environment, more research and development are necessary. this paper primarily examined the effects of high temperatures on the mechanical, microstructural, and thermal properties of concrete when fly ash was replaced with 20% by weight of the cement, graphene oxide were added by 0.08% by the weight of the cement, and their combinations i.e. (20% FA + 0.08% GO) by the weight of the cement were tested at various temperatures 200, 400, 600, and 800 °C for 4 h. The ideal temperature decided by the mechanical characteristics is 200 °C, and to understand the microstructure of graphene oxide (GO) material is essential for understanding its performance, stability, and the principles underlying its behavior, particularly at elevated temperatures. Machine learning tools such as Response Surface Methodology (RSM) and Artificial Neuron Network (ANN) have been used to forecast the mechanical properties of concrete.

Nonlinear Analysis and Optimization of Recycled Aggregate Concrete Cross-Sections Based on Restoring Force Models

This research presents a simplified approach using a uniaxial restoring force model to analyze the seismic response of recycled aggregate concrete (RAC) frames. Nonlinear simulations were conducted to explore how factors like axial compression ratio, reinforcement ratio, and cross-sectional geometry affect the ductility and seismic performance of RAC sections. The findings reveal that a reduction in the axial compression ratio from 0.60 to 0.57 results in a 15% increase in ductility, while a higher reinforcement ratio leads to a 20% enhancement. In addition, rectangular sections were found to be more sensitive to variations in material strength than square sections, offering key insights for structural optimization. The method proposed here also enhances computational efficiency by minimizing resource consumption and improving the convergence of nonlinear iterative procedures. These findings provide a theoretical foundation for optimizing the design and seismic evaluation of RAC structures, promoting their broader application in engineering practice.

Research on Material Strength Test of Pinus Sylvestris var. Mongolica Wood Supporting Adapted to LS-DYNA Programme

Research on Material Strength Test of Pinus Sylvestris var. Mongolica Wood Supporting Adapted to LS-DYNA Programme

Effect of Depth of Cut and Number of Layers on the Surface Roughness and Surface Homogeneity After Milling of Al/CFRP Stacks.

A multilayer structure is a type of construction consisting of outer layers and a core, which is mainly characterized by high strength and specific stiffness, as well as the ability to dampen vibration and sound. This structure combines the high strength of traditional materials (mainly metals) and composites. Currently, sandwich structures in any configurations (types of core) are one of the main directions of technology development and research. This paper evaluates the surface quality of II- and III-layer sandwich structures that are a combination of aluminum alloy and CFRP (Carbon Fiber-Reinforced Polymer) after the machining. The effect of depth of cut (ae) on the surface roughness of the II- and III-layer sandwich structures after the milling process was investigated. The surface homogeneity was also investigated. It was expressed by the IRa and IRz surface homogeneity indices formed from the Ra and Rz surface roughness parameters measured separately for each layer of the materials forming the sandwich structure. It was noted that the lowest surface roughness (Ra = 0.03 µm and Rz = 0.20 µm) was obtained after the milling of the II-layer sandwich structure using ae = 0.5 mm, while the highest was obtained for the III-layer structure and ae = 1.0 mm (Ra = 1.73 µm) and ae = 0.5 mm (Rz = 10.98 µm). The most homogeneous surfaces were observed after machining of the II-layer structure and using the depth of cut ae = 2.0 mm (IRa = 0.28 and IRz = 0.06), while the least homogeneous surfaces were obtained after milling of the III-layer structure and the depths of cut ae = 0.5 mm (IRa = 0.64) and ae = 2.0 mm (IRz = 0.78). The obtained results may be relevant to surface engineering and combining hybrid sandwich structures with other materials.

Leveraging Digital Intelligence for the Design and Fabrication of Urban Sculpture Art

With the rise of digital intelligent technology, its application fields are more and more extensive, including urban sculpture. This study addresses the critical factors of durability and maintenance associated with the digital components used in outdoor urban sculptures. The primary objective of this research is to employ cutting-edge digital intelligent technologies in the conceptualization and realization of urban sculpture. We introduce an innovative Efficient Generative Adversarial Network (EGAN), enhanced by fruit fly optimization (FFO), which facilitates the generation of unique patterns and designs for urban sculptures through smart sensor integration. This approach leverages a variety of data collected by smart sensors, which is subsequently preprocessed through data cleaning and normalization techniques. We apply Principal Component Analysis (PCA) for effective feature extraction, allowing for the development of intelligent digital frameworks for urban sculpture design models. Our results demonstrate that the proposed method significantly enhances design efficiency (25 hours), resolution (600 dpi), material strength (35 MPa), environmental adaptability (high), and overall durability (10 years) of urban sculpture patterns derived from smart sensor data. The digital intelligent technology-based design approach surpasses traditional methodologies in meeting the stringent standards set for urban sculpture design, thereby contributing to the future of urban art installations.

Enhancement of 316 L stainless steel mechanical properties through TiC particle introduction via metal powder injection molding

Abstract Metal powder injection molding (MIM) has been a popular technique in production of alloy materials. Through this technique, near-net-shape alloy products can be molded with one-step production. Stainless steel 316 L (SS 316 L) is an important material in aerospace and marine industry for its excellent material strength and resistance to corrosion. As the industry grows with upgraded techniques, the standard for next generation material strength has improved tremendously. Here we present a practical method strengthening SS 316 L via MIM technique, which might provide a pathway for exploration of high strength materials. TiC was introduced into SS 316 matrix with polyoxymethylene (POM) binder. The metallography indicates that the introduction of TiC facilitates the refinement of the 316 L grain. As the TiC content increases from 0 wt% to 3 wt%, the material properties improve significantly, including a rise in hardness from 151 HV to 301 HV, tensile strength from 689 MPa to 792 MPa, and yield strength from 221 MPa to 339 MPa. Additionally, there is a noticeable reduction in the coefficient of friction and the wear cross-section.

How frictional ruptures and earthquakes nucleate and evolve.

Frictional motion is mediated by rapidly propagating ruptures that detach the ensemble of contacts forming the frictional interface between contacting bodies1-7. These ruptures are similar to shear cracks. When this process takes place in natural faults, these rapid ruptures are essentially earthquakes8,9. Although fracture mechanics describe the rapid motion of these singular objects, the nucleation process that creates them is not understood10-19. Here we fully describe the nucleation process by extending fracture mechanics to explicitly incorporate finite interface widths (which are generally ignored20,21). We show, experimentally and theoretically, that slow steady creep ensues at a well-defined stress threshold. Moreover, as slowly creeping patches approach the interface width, a topological transition takes place in which these creeping patches smoothly transition to the rapid fracture that is described by classical fracture mechanics22-26. Apart from its relevance to fracture and material strength, this new picture of rupture nucleation dynamics is directly relevant to earthquake nucleation dynamics; slow, aseismic rupture must always precede rapid seismic rupture (so long as the initial defect in the interface is localized in both spatial dimensions). The theory may provide a new framework for understanding how and when earthquakes nucleate.

Theoretical model for combined sample size and strain rate effect on tensile strength of quasi-brittle materials

Theoretical model for combined sample size and strain rate effect on tensile strength of quasi-brittle materials

Estimating Missing Values in Compressive Strength of Cementitious Materials: A Machine Learning and Statistical Approach with Irregular Data

Estimating Missing Values in Compressive Strength of Cementitious Materials: A Machine Learning and Statistical Approach with Irregular Data

Assessment of Antibacterial Effect, Solubility, Fluoride Ion Release and Compressive Strength of Glass Ionomer Containing Chlorhexidine versus Conventional Glass Ionomer Restorative Material (In-vitro study)

Assessment of Antibacterial Effect, Solubility, Fluoride Ion Release and Compressive Strength of Glass Ionomer Containing Chlorhexidine versus Conventional Glass Ionomer Restorative Material (In-vitro study)

Structural alterations in alkali-sulfate-activated slag cement pastes induced by natural and accelerated carbonation

The impact of carbonation, induced at different CO2 concentrations (0.04 or 1 %), in the phase assemblages and compressive strength of Na2SO4-activated slag materials was determined. Carbonation led to Ca-bearing phases' decalcification (mainly C-(A)-S-H type gel and ettringite) forming different CaCO3 polymorphs, independent of the slag composition or carbonation conditions adopted. In specimens exposed to 0.04 % CO2, a negligible carbonation front was observed, along with a continued phase assemblage evolution and compressive strength gain after 500 days of exposure. Conversely, exposure to 1 % CO2 led to complete carbonation after 28 days, and a significant compressive strength reduction. Accelerated carbonation does not lead to the development of comparable microstructures to those observed in naturally carbonated pastes. The accelerated carbonation rates were ~ 33 times higher than those determined under natural carbonation exposure. Therefore, accelerated tests are considered unsuitable for predicting the long-term carbonation performance of Na2SO4-activated slag cements.

Finite Element Analysis for Estimating Strength and Fatigue of the APM Structure

APM stands for autonomous people mover, which is a mass transit system widely used in many airports to transport passengers between terminals. This article focuses on APM structure newly designed comprising five components namely, chassis, floor, body, roof, and support. The objective of this article is to estimate the strength and fatigue of each component to assess safety. The finite element analysis is implemented to figure out the key results in both static and fatigue load analysis as follows: maximum displacements, maximum stresses and minimum factors of safety in static load, and minimum fatigue life cycles. The grid independence test, which is a significant process in numerical method, is carried out. The results show that the maximum displacements of the chassis, floor, body, roof, and support provide 13.3, 1.13, 0.21, 2.0, and 0.06 millimeters, respectively. The maximum stresses are about 155, 138, 35.9, 167, and 58.2 MPa, respectively, which do not exceed yield strength of material. The minimum factors of safety are about 1.6, 1.8, 7.0, 1.5, and 4.3, respectively, which are in accordance with APM standards. The minimum fatigue life cycles are obtained 1.4, 1.25, 4.81, 1.03, and 2.96 million cycles, respectively, which are not less than the infinite life cycle. Thus, it is obvious that all five components of APM structure are adequate strength and safe to function.

Analyzing the inelastic response of wind-excited steel tall buildings through a reduced-order model incorporating strength and stiffness degradation along with P-Delta effects

When wind-excited tall buildings undergo vibrations beyond their linear elastic range, it becomes imperative to account for both strength and stiffness degradation and P-Delta effects. This study investigates the influence of the degradation and P-Delta effects on the inelastic response of wind-excited tall buildings through a reduced-order building model, wherein the alongwind and crosswind building responses are presumed to be contributed by the fundamental modes. The backbone curves of the hysteretic relationships between the generalized restoring forces and displacements are developed through monotonic static modal pushover analysis utilizing a high-fidelity finite element building model with consideration of P-Delta effect. A cyclic modal pushover analysis is performed to ascertain the degradation of generalized building stiffness and strength in both translation directions, stemming from the deterioration of steel material in stiffness and strength. Subsequently, a biaxial hysteretic force model is employed to depict the hysteretic relationships between generalized forces and displacements, factoring in degradation and P-Delta effects. The inelastic response of a 60-story steel building subjected to both alongwind and crosswind load excitations is quantified through response history analysis to assess the accuracy of the reduced-order building model and to evaluate the influence of degradation of material strength and pre-yield stiffness and P-Delta effects on various responses.