Mechanical Properties Of Materials Research Articles

Effect of laser surface treatment on microstructural evolution and mechanical properties of a Co–Cr–Fe–Ni–Mo medium–entropy alloy

In this study, we explored the influence of laser surface treatment on the microstructural evolution and mechanical properties of a Co17.5Cr12.5Fe55Ni10Mo5 medium-entropy alloy. After laser scanning on the cold-rolled alloy, a heterogeneous microstructure with Mo-rich μ-precipitates formed along the depth from the surface. Notably, laser processing parameters, including scanning speed and the number of scans, affected the macroscopic heterogeneity in the microstructure of the alloy, such as the thickness of the columnar, recrystallized, partially-recrystallized, and non-recrystallized layers. Furthermore, the microstructural features of the laser-treated alloys with a heterogeneous distribution of grains, cellular structures, and precipitates, contributed to the mechanical response of the alloys. As the heat input from the laser heat source increases, the grain coarsening and the absence of non-recrystallized layer have a greater impact on the strength of the laser-treated alloys, even if the precipitates distributed deeper from the surface. These microstructural modifications through laser surface treatment are linked to variations in the mechanical performance of the alloys, indicating that it can be an effective method to tailor the mechanical properties of structural materials.

RAGN-R: A multi-subject ensemble machine-learning method for estimating mechanical properties of advanced structural materials

RAGN-R: A multi-subject ensemble machine-learning method for estimating mechanical properties of advanced structural materials

Preparation of modified epoxy resin with high hydrophobicity, low dielectric constant, toughness, and flame retardant by epoxy-functionalized siloxanes

A series of α, ω-dimethylglycidoxypropyl-terminated PDMS oligomer (PDMS-GE) oligomers with different polymerization degrees were synthesized and used to modify the bisphenol-A diglycidyl ether E51 (DGEBA) / 4,4-diaminodiphenylmethane (DDM) epoxy resin, resulting in epoxy resins with high hydrophobicity, low dielectric constant, good impact toughness, low combustion heat release rate, and low total heat release. The combustion heat release rate and total heat release of the material decreased with the increase in the loadings of PDMS-GE. Relative to pure epoxy resin, the composite E51/D30–10, which using DGEBA as the matrix, PDMS-GE with a degree of polymerization of 30 as the modifier in an amount of 10 phr relative to the mass sum of DGEBA, PDMS-GE and DDM, exhibited the best comprehensive performance with a water contact angle of 102.42°, a dielectric strength of 6.49 kV/mm, a dielectric constant of 2.93 at 14.2 GHz, the peak rate of heat release (PRHR) and total heat release (THR) are of 378.3 kW/m2 and 134.4 MJ/m2, respectively. These comprehensive performances underscore the potential of PDMS-GE oligomers in significantly improving epoxy resin properties. When the loadings of PDMS-GE oligomers are less than 5 wt%, PDMS-GE with a lower degree of polymerization can improve the toughness of epoxy resins. The impact strength of the composite E51/D24–5, which uses DGEBA as the matrix, PDMS-GE with a degree of polymerization of 24 as the modifier in an amount of 5 phr relative to the mass sum of DGEBA, PDMS-GE, and DDM, reaches 98.1 kJ/m2, which is about 28.9 % higher than that of pure epoxy resin. The results also indicated that the degree of polymerization of PDMS-GE oligomers has less influence on the dielectric properties and mechanical properties of composite materials.

The dominating dimensionless numbers of adiabatic shear localization

Adiabatic shear is a complex phenomenon involving thermo-mechanical coupled failure mechanisms, which is affected by material properties, loads, and geometries. In this study, four dimensionless numbers which only contain input parameters and can fully reflect the influence of adiabatic shear are determined by reducing the conservation equations of shear localization to dimensionless terms. The dimensional analysis method of adiabatic shear, along with predictive models for the characteristic parameters of adiabatic shear, are systematically provided by revealing the physical significance of the dimensionless numbers. Based on data analysis, a dimensional analysis method of adiabatic shear for multi-physical processes is proposed, which has been successfully applied to explosively-driven metal shells, to realize the prediction and control of adiabatic shear. This study demonstrates that the prediction models of adiabatic shear-band spacing and width can be unified through a relationship involving the Prandtl number, Pr. Furthermore, the classical prediction models of spacing and width are improved based on the experimental data. It is clearly pointed out that the more favorable the formation of shear localization, the smaller the width and spacing of the shear band, which illustrates the influence of material properties and loads on the spatial distribution of shear bands. In addition, a new prediction model for the propagation velocity of the shear band including Pr is proposed by using dimensional analysis. Compared with the classical model, the new model has higher accuracy, and can correctly reflect the influence of loads, material mechanical and thermophysical properties on the shear-band velocity.

In Situ Synthesis of MoSi2-SiC Composites by Two-Step Spark Plasma Sintering

The effect of different SiC doping content on the properties of MoSi2-based composites was analyzed in this study. The MoSi2-SiC composites were fabricated in situ by the SPS technique, utilizing self-synthesized carbon-containing Mo powder and Si powder as raw materials. A two-step sintering process was employed to ensure the formation of a uniform and dense composite structure. The microstructures and mechanical properties of these composites with various compositions were characterized. The results show that the composites were primarily composed of MoSi2, SiC, and a minor proportion of MoSiC phase. The introduction of SiC as a second phase was found to considerably enhance the mechanical properties of the MoSi2 matrix material. In particular, the MoSi2-26mol.%SiC sample exhibited Vickers hardness, fracture toughness, and flexural strength values of 16.1 GPa, 6.7 MPa·m1/2, and 496 MPa, respectively, corresponding to increases of 33%, 24%, and 28% compared to the pure MoSi2 material.

Influence of thread pitch on material flow and mechanical properties of stationary shoulder friction stir lap welded dissimilar joint

To investigate the influence of varying pitch values on the flow behavior of materials and the mechanical attributes of stationary shoulder friction stir lap welded (SSFSLW) joints. In this paper, three kinds of tools with different pitches are designed, and the lap joint of a 6061-T6 aluminum alloy plate and an AlSi10MnMg alloy plate was realized by stationary shoulder friction stir welding. Different computational fluid dynamics (CFD) models of friction stir lap welding were founded and the connection between the pitch and material flow behavior was investigated. The increased pitch pin boosts the velocity of material in the shear layer, expands flow area of aluminum alloy material, and promotes materials flow upward along the orientation of pin thread. The pin with a 1 mm pitch results in a joint that featuring the shortest hook extension distance, the largest effective sheet thickness (EST), and the largest effective lap width (ELW). The fracture locations of shear testing are all on the base material of AlSi10MnMg alloy. Numerous dimples could be seen at the fracture appearance, and the type of fracture is ductile fracture.

Janus Asymmetric Cellulosic Triboelectric Materials Enabled by Gradient Nano‐Doping Strategy

AbstractThe rapid development of wearable electronic devices has posed higher demands on the design strategies of advanced sensing materials. Multidimensional functionality and energy self‐sufficiency have consistently been focal points in the field of wearable sensing. The construction of biomimetic nanostructures in sensing materials can endow sensors with intrinsic response characteristics and derivative performance. Here, inspired by the Janus structure and function of human skin, a gradient nano‐doping strategy is proposed for developing cellulosic triboelectric materials with biomimetic‐ordered Janus asymmetric structures. This strategy integrates the complementary advantages of internal components and structures to meet the complex requirements of self‐powered sensing materials. The triboelectric material simultaneously achieves high electrical output power (2.37 W m−2), excellent mechanical properties (withstanding tensile forces over 20 080 times its weight), and thermal conductivity. The wearable self‐powered wireless sensing system designed accordingly demonstrates excellent sensitivity (27.3 kPa−1) and sustained performance fidelity (15 000 cycles), faithfully recording human motion training information. This research holds significant research value and practical implications for the material structure, mechanical properties, and application platforms of wearable electronic devices.

Investigation of the Critical Buckling Temperatures and Free Vibration Response of Porous Functionally Graded Magneto-Electro-Elastic Sandwich Higher-Order Nanoplates with Temperature-Dependent Material Properties

PurposeThis article aims to determine the critical buckling temperature and thermomechanical free vibration response of a porous functionally graded material (FGM) nanoplate sandwiched between porous magneto-electro-elastic (MEE) plate layers, taking into account temperature-dependent material properties.MethodsThe upper surface of the FGM host structure is considered zirconia (ZrO ), and the lower surface is stainless steel (SUS304). In addition, the MEE face layers are considered to be homogenous volumetric mixtures of cobalt-ferrite (CoFe O ) and barium-titanate (BaTiO ). It is assumed that the host structure’s effective mechanical and thermal material properties are graded in the thickness direction according to the power law distribution. The effective mechanical, electrical, thermal, and magnetic properties of the face plates are obtained by the rule of mixture. This study was conducted using sinusoidal higher-order shear deformation theory (SHSDT) and nonlocal strain gradient elasticity theory (NSGT). Hamilton's theory is utilized to derive the equations of motion of sandwich nanoplates. Closed-form solutions are obtained by the use of Navier's method.ResultsParametric simulations are carried out to examine the effects of the power law index, nonlocal parameters, electric, magnetic, and thermal loads, porosity volume fraction, porosity distribution and volume ratio of CoFe O and BaTiO on the free vibration and buckling behavior of the nanoplate. The results of the simulations are compared with published works to verify the accuracy of the proposed method.ConclusionAccording to the analysis results, it is determined that the power law index, porosity ratio, porosity distribution function, temperature dependent properties, magneto-electro-thermo-mechanical loads and nonlocal factors significantly affect the thermomechanical behavior of the nanoplate.

Effective Mechanical Properties of a Composite Material Reinforced by Oil Shale Ash Particles

This study determined the elastic properties of composites and concretes reinforced with oil shale ash (OSA) particles, a byproduct of oil shale combustion in an electric power plant in Estonia (Auvere). Since 2018, OSA has no longer been classified as hazardous waste in the EU, enabling its reuse in sustainable materials. The present research examined the effect of OSA on the elastic properties of epoxy–OSA and concrete–OSA composites. The experimental results show that the elastic modulus of epoxy resin increases with an increase in the ash concentration, while it decreases in concrete with a higher OSA content. Theoretical models, including the rule of mixtures, finite element method (FEM), Mori–Tanaka method, and Halpin–Tsai method, were used to predict these properties numerically. The rule of mixtures and FEM generally overestimated the modulus for epoxy–OSA, whereas the Mori–Tanaka and Halpin–Tsai methods provided closer predictions. For concrete–OSA, the compressive strength tests followed the LVS EN 12390-3:2019 standards, with elastic modulus conversions being made via IS 456:2000 Clause 6.2.3.1, which showed a variable decrease across different strength classes. The findings highlight the potential of OSA as a reinforcing filler in construction materials, promoting environmental sustainability by repurposing industrial waste while offering mechanical benefits.

Sensitive Mechanism and Instability Modeling Methods of Flexible Sensing Films Based on 2D Materials

This paper examines sensing mechanisms and stability issues of flexible sensors used in morphing wing applications. A key challenge is the lack of theoretical frameworks that accurately predict sensor behavior during complex deformation. Current models struggle to fully capture the relationships between mechanical strain, electrical response, and material properties. We first analyze the microscopic mechanisms and macroscopic sensing characteristics of 2D material-based sensitive films, developing strain-sensitive models based on crack effects and pressure-sensitive models based on slip effects. Through power spectrum analysis, we establish a quantitative model linking microscopic cracks to macroscopic electrical properties. Using this model, we study the factors affecting flexible sensing stability and propose a quantitative description model using dual-layer multi-channel flexible sensors. After simulation validation, our model successfully guides the structural design of flexible sensing films, offering a clear approach to improve flexible sensor stability.

Study on the mechanics and self-sensing properties of ultrahigh-performance shotcrete containing waste glass aggregates

To promote the recycling of waste glass and satisfy the demands of environmental sustainability for ultrahigh performance concrete (UHPC), in this study, glass sand was employed to partially or entirely replace machine-made sand, and steel fibres were incorporated to fabricate ultrahigh performance shotcrete (UHPS). The effects of glass sand and steel fibres on the mechanical and electrical properties of composite materials were analysed in this study. Furthermore, alkali‒silica reaction (ASR) tests and microstructural analyses were conducted. The results indicate that at higher steel fibre contents, the incorporation of glass sand does not reduce the compressive strength of the UHPS and that glass sand has no significant effect on the split tensile or flexural strength. When the steel fibre content is 2% and the replacement ratio of glass sand reaches 100%, the mechanical properties of the UHPS reach their maximum. The addition of glass sand negatively affects the electrical properties, whereas the use of steel fibres improves them. The results of the alkali‒silica reaction tests confirm that the use of glass sand does not induce harmful expansion reactions. The study revealed the trends in the mechanical and electrical properties of concrete from a microstructural perspective and provided explanations for the alkali‒silica reaction outcomes. This study provides technical support for the application of UHPS to tunnel linings.

Adhesive and Conductive Fibrous Hydrogel Bandages for Effective Peripheral Nerve Regeneration.

Peripheral nerve injury is a common disease resulting in reversible and irreversible impairments of motor and sensory functions. In addition to conventional surgical interventions such as nerve grafting and neurorrhaphy, nerve guidance conduits are used to effectively support axonal growth without unexpected neuroma formation. However, there are still challenges to secure tissue-mimetic mechanical and electrophysiological properties of the conduit materials. Herein, the phenylborate-tethered hydrogel-assisted doping effect is elucidated on conductive polymers, enhancing peripheral nerve regeneration when used as a sutureless bandage on the injured nerve. The adhesive and conductive nerve bandage consists of biocompatible hyaluronic acid hydrogel microfibers produced by electrospinning, followed by in situ conductive polypyrrole polymerization on the fibrous mat. Particularly, phenylborate groups enable high adsorption of pyrrole without mechanical crack on the hydrogel network and allow tissue-like stretchability and on-nerve adhesiveness. In a rat crushed nerve injury model, the nerve bandage can effectively promote nerve regeneration through stable sutureless wrapping followed by great electrical transmission on the defect region, showing anatomical and functional recovery of the nerve tissues and preventing muscular atrophy. Such hydrogel fibrous bandages will be a promising surgical dressing to be combined with versatile biomedical devices/materials for peripheral nerve repair.

Effects of Hypergravity on Phase Evolution, Synthesis, Structures, and Properties of Materials: A Review

In a hypergravity environment, the complex stress conditions and the change in gravity field intensity will significantly affect the interaction force inside solid- and liquid-phase materials. In particular, the driving force for the relative motion of the phase material, the interphase contact interaction, and the stress gradient are enhanced, which creates a nonlinear effect on the movement mode of the phase material, resulting in a change in the material’s behavior. These changes include increased stress and contact interactions; accelerated phase separation; changes in stress distribution; shear force and phase interface renewal; enhanced interphase mass transfer and molecular mixing; and increased volume mass transfer and heat transfer coefficients. These phenomena have significant effects on the synthesis, structural evolution, and properties of materials in different phases. In this paper, the basic concepts of hypergravity and the general rules of the effects of hypergravity on the synthesis, microstructure evolution, and properties of materials are reviewed. Based on the development of hypergravity equipment and characterization methods, this review is expected to broaden the theoretical framework of material synthesis and mechanical property control under hypergravity. It provides theoretical reference for the development of high-performance materials under extreme conditions, as well as new insights and methods for research and application in related fields.

Influence of Printing Orientation on the Mechanical Properties of Provisional Polymeric Materials Produced by 3D Printing

Influence of Printing Orientation on the Mechanical Properties of Provisional Polymeric Materials Produced by 3D Printing

Fabrication and mechanical properties of porous tantalum carbon composites by chemical vapor deposition

This study investigates the deposition of tantalum (Ta) coatings on carbon foams using the chemical vapor deposition (CVD) method to enhance their compressive strength. Two types of open-cell carbon foams, CF-1 and CF-2, with different strut diameters, were examined. The morphology and uniformity of the coatings were characterized, and the effect of coating thickness on the compressive strength of the foams was systematically analyzed. An empirical model was proposed and successfully validated, showing that the compressive strength is proportional to the coating thickness and the square of the strut diameter. The experimental results demonstrate that considering mass transfer and reaction kinetics can significantly improve the uniformity of coatings on larger substrates. Furthermore, the Ta coatings significantly increased the compressive strength of the foams, with the relationship between compressive strength, coating thickness, and strut diameter being in good agreement with the predictions of the proposed model. The study highlights the potential of tailored metallic coatings to enhance the mechanical properties of porous materials while maintaining their lightweight characteristics, emphasizing the importance of optimizing coating parameters for large-scale applications.

Influence of modifying additives on the structure and properties of biodegradable mixtures based on poly-3-hydroxybutyrate and nitrile butadiene rubber

Objectives. To investigate polymer composite materials based on poly-3-hydroxybutyrate (PHB) of microbiological origin and the synthetic nitrile butadiene rubber NBR-28. The biodegradability of PHB implies the possibility of its use for invasive medical purposes; however, this is significantly limited by its brittleness. The aim of this work was to search for approaches to altering the molecular structure of PHB-based composites, in order to impart them with sufficient physical and mechanical characteristics and increase their compatibility without violating biodegradability.Methods. Reaction mixtures contained the elastic material NBR-28, various modifiers (sorbitan oleate, epoxidized soybean oil, siloxane rubber), and additional polymer components (ethylene–vinyl acetate copolymer and polybutylene adipate terephthalate). The mixtures were prepared in a PL 2200-3 plasticorder (Brabender, Russia) by pressing, holding the material at 180°C under pressure for 3 min followed by quenching in cold water. The surfaces of the films and plates of the mixtures were studied using an Axio Imager Z2m optical microscope (Carl Zeiss, Germany) with the Axio Vision software at 50× and 200× magnification in reflected light. The mechanical properties of materials under tension were measured using an Instron 3365 universal tensile testing machine (Instron, United Kingdom).Results. The role of modifiers and polymer additives in the PHB–NBR-28 composites and their influence on the morphology of mixtures, crystallinity, and mechanical characteristics were established. The introduction of modifiers made it possible to reduce the average particle size of the NBR-28 phase in the PHB matrix by 30–50%, additionally changing their morphology. In this case, the uniformity of particle distribution increased, having a positive effect on the mechanical characteristics of the systems.Conclusions. It was shown that the modifiers change the morphology of mixtures, reduce the average particle size of the NBR phase by 30–50%, and positively affect the strength of the systems. Owing to changes in the structure of their interfacial layers and, as a consequence, physical and mechanical characteristics, the resulting composites render suitable for use in reparative bone and dental surgery, as well as for creating wound healing materials.

Optimizing high-pressure sliding process parameters for grain refinement and enhanced mechanical properties using response surface methodology approach

Lightweight technology has emerged as a crucial focus within transportation machinery manufacturing, driving the pursuit for materials with exceptional strength-to-weight ratios. To address this need, ultra-fine grain (< 500 nm) and nanostructured (< 100 nm) materials are being developed using severe plastic deformation (SPD) techniques, particularly in confined flat sheets. This study focuses on the Multi Pass Incremental Feed High-Pressure Sliding (MPIF-HPS) technique, which offers significant potential for industries such as aerospace and automotive by enhancing the mechanical properties of materials like AA 7075 alloy. This work investigates the development and characterization of ultrafine-grained materials through SPD, focusing on the correlation between ultrafine grain structures and their distinct properties. Utilizing MPIF-HPS processes and design of experiment (DoE) methodologies, the study evaluates the evolution of fine-grained microstructures and the enhancement of boundary characteristics with increasing strain in AA 7075 alloy. The grain size was refined from 600 µm to 6 µm, indicating significant microstructural improvement. Concurrently, mechanical properties were notably enhanced, with hardness increasing from 102 to 165 HV, yield strength from 250 to 605 MPa, and ultimate tensile strength (UTS) from 400 to 650 MPa. The study systematically optimized processing parameters, including pressure, sliding distance, and number of passes, to determine the ideal conditions for grain refinement and mechanical performance. These findings underscore the critical role of strain-induced boundary characteristics in determining the material's final properties, paving the way for tailored solutions to meet specific industrial requirements.

Biomechanical behavior of titanium, cobalt-chromium, zirconia, and PEEK frameworks in implant-supported prostheses: a dynamic finite element analysis

BackgroundThe mechanical properties of framework materials significantly influence stress distribution and the long-term success of implant-supported prostheses. Although titanium, cobalt-chromium, zirconia, and polyether ether ketone (PEEK) are widely used, their biomechanical performance under dynamic loading conditions remains insufficiently investigated. This study aimed to evaluate the biomechanical behavior of four framework materials with different Young's modulus using dynamic finite element stress analysis.MethodsA 3D edentulous maxillary model was extracted from a computer tomography (CT) database. Bone level implants with conical connection designs were placed in the anterior (canine) and posterior (first molar) areas. Anterior implants were parallel, yet posterior implants were inclined distally by 30 degrees. According to the framework material, four groups were formed: cobalt-chromium (Co-Cr), zirconia (Zr), titanium (Ti), and polyether ether ketone (PEEK). For each framework material, twelve separate models of analysis were created by applying force in three different orientations. Dynamic forces were employed to replicate the chewing process. Principal and von Mises stresses were measured and evaluated.ResultsThe PEEK framework exhibited the highest maximum von Mises stress values (372.55 MPa) on the abutment and the highest maximum principle stress values (59.27 MPa) in the cortical bone. The Co-Cr framework had the lowest minimum principle stress (3.98 MPa) in the trabecular bone. The displacements of the Co-Cr, Zr, Ti, and PEEK frameworks were 0.15 mm, 0.15 mm, 0.17 mm, and 0.35 mm, respectively.ConclusionFrameworks having a greater Young's modulus are less susceptible to deformation.

Effect of the Degree of Crystallinity of Base Material and Welded Material on the Mechanical Property of Ultrasonically Welded CF/PA6 Joints.

Ultrasonic welding (USW) is considered one of the most suitable methods to join semi-crystalline carbon fiber-reinforced thermoplastics (CFRTPs). The degree of crystallinity (DoC) of the semi-crystalline resin will affect the ultrasonic welding process by affecting the mechanical properties of the base material. In addition, ultrasonic welding parameters will affect the joint performance by affecting the DoC of the welded material at the welding interface. This paper investigates the effect of DoC of carbon fiber-reinforced PA6 (CF/PA6) base material and welded material on its ultrasonically welded joints' performance. Distinct pre-welding heat treatments are conducted on the base material before welding. The DoC is calculated by DSC, while the crystalline phases (α and γ phases) and crystallize size are determined using XRD. The results demonstrate that the heat treatment process of heating temperature of 180 °C and cooling with an oven (180-O) could increase the DoC of CF/PA6 from 27.2% to 33% and the ratio of α/γ from 0.38 to 0.75. The joint strength of 180-O sheets reached 17.7 MPa, which is 26.7% higher than that of the as-received sheets. The DoC of the welded material at the welding interface obtained with different combinations of welding parameters is characterized. Higher welding force and amplitude result in faster cooling rate at the welding interface and more effective strain-induced crystallization, leading to higher DoC of the welding interface.

Preparation and properties of graphene/β-SiC-toughened ceramics

The brittleness of silicon carbide restricts its wide application. Graphene as a superior second-phase material can improve the toughness and brittleness of silicon carbide. In this article, a graphene/β-SiC ceramic material was prepared with 1–3 wt.% graphene added in β-SiC matrix via pressure-free sintering at 2120°C for 60 min. The effect of the graphene addition on the phase composition, bulk density, porosity, and mechanical properties of ceramic material was investigated. The results show that the bulk density of graphene/β-SiC ceramic material decreases, the porosity of openings increases, and the bending strength, hardness, as well as fracture toughness firstly increase and then decrease as graphene addition increases. Compared with β-SiC ceramic without graphene, the optimum properties of graphene/β-SiC ceramic with graphene addition of 1 wt.% (i.e. a fracture toughness of 5.07 MPa m1/2, bending strength of 410.84 MPa and hardness of 27.72 HV) can be obtained, which are increased by 35.56%, 13.35%, and 3.8%, respectively. The fracture morphology indicates that the crack deflection is the main mechanism of toughening β-SiC ceramic with graphene.