Evolution Of Mechanical Properties Research Articles

Generalized incremental moduli of hyperelastic materials

Abstract The field of hyperelasticity, though well established for isotropic materials, remains an area of ongoing research, particularly regarding the evolution of mechanical properties as a function of strain state. This paper presents a generalized approach to calculating incremental moduli, which describe material stiffness under any given stress-strain condition, extending traditional incremental moduli definitions used for uniaxial, volumetric and shear stress situations. In detail, given a hyperelastic potential and the stress corresponding to a generic strain state, the approach allows the identification of generalized incremental Young's moduli, Poisson's ratios, shear moduli, and bulk modulus corresponding to such generic stress state. The approach reveals the progressive stiffening, softening and anisotropization of the material under deformation, which contrasts with the behavior of materials with fixed stiffness properties, such as linear elastic ones. The method is applied to a compressible neo-Hookean material to evaluate its mechanical response under uniaxial, volumetric, and deviatoric stress-strain states. The results show that under uniaxial loading or deviatoric loading, the generalized incremental moduli exhibit directional sensitivity, demonstrating the material's increasing anisotropic behavior as strain progresses. In contrast, isotropic trends are maintained under volumetric deformations. This study provides valuable insight into the evolution of material properties during whatever loading condition and offers a more general framework for understanding and characterizing the behavior of hyperelastic materials.

Boosting biocompatibility and mechanical property evolution in a high-entropy alloy via nanostructure engineering and phase transformations

Boosting biocompatibility and mechanical property evolution in a high-entropy alloy via nanostructure engineering and phase transformations

Investigation of the synergistic evolution of mechanical properties governed by composition–process–microstructure coupling in ultra-long flow die-cast aluminum alloys

Investigation of the synergistic evolution of mechanical properties governed by composition–process–microstructure coupling in ultra-long flow die-cast aluminum alloys

Annealing-induced microstructure and mechanical property evolution of helium-irradiated Cr coatings

Annealing-induced microstructure and mechanical property evolution of helium-irradiated Cr coatings

Study on the Mechanical Properties and Degradation Mechanisms of Damaged Rock Under the Influence of Liquid Saturation

To investigate the degradation mechanisms of the surrounding rock in abandoned mine roadways used for oil storage, this study combined uniaxial compression tests with digital image correlation (DIC), scanning electron microscopy (SEM), and other techniques to analyze the evolution of the rock mechanical properties under the coupled effects of oil–water soaking and initial damage. The results indicate that oil–water soaking induces the loss of silicon elements and the deterioration of microstructure, leading to surface peeling, crack propagation, and increased porosity of the sample. The compressive strength decreases linearly with the soaking time. Acoustic emission (AE) monitoring showed that after 24 h of soaking, the maximum ringing count rate and cumulative count decreased by 81.7% and 80.4%, respectively, compared to the dry state. As the liquid saturation increases, the failure mode transitions from tension dominated to shear failure. The synergistic effect of initial damage and oil–water erosion weakens the rock’s energy storage capacity, with the energy storage limit decreasing by 45.6%, leading to reduced resistance to external forces.

The Influence of Aging Temperature and Cryogenic Treatment on the Mechanical Properties and Microstructure of Extruded Mg-8Gd-3Y-0.4Zr Alloy

This investigation implemented an integrated aging–cryogenic thermal processing method for extruded Mg-8Gd-3Y-0.4Zr alloy to further improve its performance and broaden its scope of application, employing a characterization approach combining optical microscopy (OM), electron backscatter diffraction (EBSD), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The comprehensive microstructure characterization was systematically correlated with mechanical property evolution to establish structure–property relationships. The results show that aging combined with cryogenic treatment significantly enhances the hardness and improves the microstructure of magnesium alloys. Specimens aged at 210 °C for 20 h followed by one-hour cryogenic treatment exhibited the highest average hardness (113.5 HV), representing a 11.2–25% improvement compared to those aged at lower temperatures. This enhancement can be attributed to the elevated aging temperature promoting substantial precipitation and subsequent growth of second phases such as Mg3(Gd,Y), which benefit from sufficient thermal activation energy. The increased density and larger dimensions of these second phases contribute to enhanced hardness through elevated internal stress generation. However, their non-uniform distribution may induce localized stress concentration, consequently reducing hardness uniformity. Notably, specimens subjected solely to 210 °C aging for 20 h showed marginally lower hardness compared to their cryogenically treated counterparts, suggesting that although cryogenic treatment may refine grain structures and introduce dislocation defects to enhance hardness, its concurrent reduction in residual stresses might limit the overall improvement magnitude.

Numerical Modeling of Micro-Mechanical Residual Stresses in Carbon–Epoxy Composites During the Curing Process

This article analyzes the residual stresses generated during the curing process of thermoset composites. Specifically, a numerical procedure is developed and implemented in Ansys 18.0 to evaluate, at the micromechanical level, the residual stresses in a carbon epoxy composite that undergoes the process of curing. The viscoelastic behavior of the epoxy material is modeled using a formulation recently published by the same authors. It accounts for the concurrent effect of curing and structural relaxation on epoxy’s relaxation times, assuming thermo-rheological and thermo-chemical simplicities. The model validated for the neat epoxy matrix is now tested against the composite application. Various representative volume element (RVE) arrangements and fiber fractions are examined. The proposed procedure can predict the evolution of mechanical properties (apparent stiffness and creep compliance) and the residual stresses that develop in each composite constituent during the cure. It demonstrates that the residual stresses in the matrix are a consistent fraction of an epoxy’s nominal strength and significantly influence the transverse mechanical properties of the composite.

Evolution of Microstructure and Mechanical Properties of Steam Generator Material After Long-Term Operation in Nuclear Power Plant

The microstructural evolution and mechanical properties of WWER 440 steam generator steel GOST 22K after long-term operation were thoroughly examined in this study. The samples were taken directly from a steam generator using the small punch test method. The uniqueness of these samples lies in the fact that they were real operating materials used in a nuclear power plant with different years of operation. The microstructure was characterized using optical microscopy and transmission electron microscopy supplemented by selective electron diffraction and semi-quantitative chemical microanalysis. It was found that with the prolongation of the operation time of the steam generator, the density of carbides increased slightly, which was reflected in a decrease in the mean distance between particles, but these differences were very small, which indicates the microstructural stability of GOST 22K steel. The stability of this steel was also confirmed by measuring its mechanical properties, which changed only minimally depending on the years of operation. The tensile strength values were in the range of 508 to 579 MPa. In the case of the ductile-to-brittle transition temperature (DBTT), a slight increase was found after 6 years of operation. The DBTT did not change significantly with subsequent operation.

Quantitative mapping of internal structural parameters to mechanical properties of asphalt concrete using principal component analysis

ABSTRACT Characterizing the evolution of internal structural parameters and mechanical properties in asphalt concrete is challenging due to its complex, random internal structure. This study proposes a mapping framework between internal structural "gene units" and mechanical behavior using the material genome concept. Semicircular bending (SCB) tests with Digital Image Correlation (DIC) were performed to extract peak load (Fmax) and maximum horizontal strain (Exx) under controlled conditions. Fourteen internal structure parameters – comprising aggregate contact and pore distribution characteristics – were quantified through digital image processing and 3D X-ray CT reconstruction. Principal component analysis (PCA) followed by multivariate linear regression was employed to correlate structure with performance. The results revealed that the coefficients of variation for macroscopic mechanical indexes and peak strain were 13.14% and 21.01%, respectively. Durbin–Watson statistics of 2.442 (Fmax) and 2.414 (Exx) suggest no significant first-order autocorrelation in the model residuals. The R2 values for the prediction models of peak load and maximum horizontal strain based on internal structural parameters were 0.925 and 0.889. These results demonstrate that the proposed preliminary framework effectively captures the influence of internal structure on asphalt concrete mechanical behaviour, providing a foundation for future data-driven optimisation of mixture design.

Interlayer time as a robust, geometry-agnostic predictor of microstructural and mechanical properties evolution in PBF-LB/M Ti6Al4V alloy

Interlayer time as a robust, geometry-agnostic predictor of microstructural and mechanical properties evolution in PBF-LB/M Ti6Al4V alloy

Tracing the evolution of microstructures, mechanical properties and corrosion behaviors of as-rolled Mg-Y and Mg-Y-Ca alloys during heat treatment

Tracing the evolution of microstructures, mechanical properties and corrosion behaviors of as-rolled Mg-Y and Mg-Y-Ca alloys during heat treatment

Microstructural and mechanical properties evolution of alloy C-HRA-2 aging at 800 °C for up to 10,000 h

Microstructural and mechanical properties evolution of alloy C-HRA-2 aging at 800 °C for up to 10,000 h

Characterization of Mechanical Property Evolution and Durability Life Prediction of Engineered Cementitious Composites Under Frozen State.

Engineered cementitious composites (ECCs) exhibit superior mechanical properties (MPs) and excellent crack control capabilities, making them widely used in practical engineering applications. However, the MPs of ECCs in frozen states (FSs), particularly their flexural properties (FPs), still need to be better understood. MP tests were designed for frozen ECC samples to investigate the service performance of ECCs in an FS. The samples underwent 0 to 300 freeze-thaw cycles (FTs), followed by compressive and flexural tests at a constant freezing temperature of -18 °C. The compressive properties (CPs) and FPs of the samples and their influencing mechanisms were analyzed. Based on this analysis, a life prediction model (LPM) for freeze-thaw-damaged (FTD) ECCs was established using the entropy weight method and the GM(1,1) model to predict the durability changes of ECCs in FS. The results indicate that with an increasing number of FTs, the uniaxial compressive strength (CS), elastic modulus (E), initial crack strength, and ultimate strength of ECCs in the FS are higher than those in the thawed state (TS), with a notable increase in brittleness at ultimate failure. The overall stiffness of the specimens increased under high FTs. The established model effectively predicts the durability changes of ECCs in the FS.

Evolution of Microstructure and Mechanical Properties of Electron Beam Irradiated Electro-explosive Al-Y2O3 Coatings

Evolution of Microstructure and Mechanical Properties of Electron Beam Irradiated Electro-explosive Al-Y2O3 Coatings

Research on the Interlayer Bonding and Temperature Control Optimization of Asphalt Concrete Core Wall.

In this paper, the mechanism of interlayer bonding under a low-temperature environment is systematically revealed in terms of the temperature control difficulties in the continuous multilayer construction of an asphalt concrete core wall in winter. A field simulation paving test was conducted using a temperature-controllable simulated paving system, and the key laws of the temperature transfer and mechanical property evolution were discovered by precisely regulating the surface temperature of the bonded surface (the test range covered from -5 °C to 70 °C). This study shows that a bonding surface temperature of 40 °C is a critical point of engineering importance, at which the material exhibited a unique performance compensation effect. Under this temperature condition, although the mechanical index was reduced compared with the parent material, the flexural strength was reduced by 11.39%, the maximum bending strain was reduced by 9.65%, the tensile strength was reduced by 7.89%, the critical tensile strain was reduced by 16.11%, and the crack curvature coefficient was reduced by 10.06%. However, thanks to the unique structural reorganization characteristics of asphalt materials, these performance losses were effectively compensated, thus ensuring the stability of engineering applications. In particular, a fast rise-stable-slow decline evolution law of the interlayer temperature transfer was found, proving the existence of a temperature-adaptive interval of the bond surface. The research results not only enrich the theory of asphalt concrete interlayer bonding but also provide innovative technical solutions for the construction of water conservancy projects in cold regions. In particular, the fast rise-stable-slow drop evolution law of the interlayer temperature transfer was found, which proves the existence of a temperature-adaptive interval of the bond surface. The research results not only enrich the theory of asphalt concrete interlayer bonding but also provide innovative technical solutions for the construction of water conservancy projects in cold regions.

A Reference Hydride Ratio Method for the Resolution of Al/Fe Peak Overlapping in Atom Probe Tomography Experiments.

Precise Fe concentration measurements are essential to understand the kinetics of precipitation and evolution of mechanical properties in Al-Fe alloys. Moreover, with the increasing proportion of recycled metals, it is mandatory to rely on techniques capable of tracking impurities in Al-alloys to elucidate their effects on microstructure and properties. Atom Probe Tomography (APT) is a powerful material analysis tool capable of precise composition measurements. As it relies on time-of-flight mass spectrometry, the quality of the composition measurements is highly dependent on the proper peak identification and solving peak overlapping. The complexity of peak decomposition multiplies if molecular ions such as hydrides or oxides are present in the mass spectrum. Al-Fe is one of these systems, where three out of four peaks of Fe isotopes are overlapping with Al, AlH, and AlH2 mass intervals. To solve this complex peak overlapping case, an approach has been developed here. It is based on acquiring the Al-hydride formation ratio from APT analyses of standard materials, where no overlap with Fe peaks is observed. This simple method aims to improve the precision of Fe concentration measurements in Al-Fe system.

Evolution of mechanical properties and microstructure of high alumina porcelain insulators with sintering temperature

Evolution of mechanical properties and microstructure of high alumina porcelain insulators with sintering temperature

Microstructure and Mechanical Properties Evolution of C-HRA-5 Steel After High-Temperature Service

Microstructure and Mechanical Properties Evolution of C-HRA-5 Steel After High-Temperature Service

Self-lubricating ceramic-fluoride composite coatings for seawater/atmospheric environments: Evolution of microstructure, phase, mechanical, corrosion and tribological properties

Self-lubricating ceramic-fluoride composite coatings for seawater/atmospheric environments: Evolution of microstructure, phase, mechanical, corrosion and tribological properties

The element enrichment behavior during the aging treatment of PH13–8Mo steel and its influence on the evolution of microstructures and mechanical properties

The element enrichment behavior during the aging treatment of PH13–8Mo steel and its influence on the evolution of microstructures and mechanical properties