Showing papers on "Stress–strain curve published in 2022"
TL;DR: In this article , the authors proposed a fully recycled aggregate concrete (FRAC), which was prepared by completely replacing natural aggregates (NA) with recycled coarse and fine aggregates and partially replacing cement with recycled powder (RP).
66 citations
TL;DR: In this article , a design-oriented stress-strain model was developed to predict the axial stress and strain relationship of FRP-confined UHPC cylinders under axial compression.
49 citations
TL;DR: In this paper, the elastic modulus, peak strain, ultimate strain and peak stress were calculated through the experimental complete stress-strain curves, and the relationship between the mechanical properties and mass loss was explored.
30 citations
TL;DR: In this paper , the elastic modulus, peak strain, ultimate strain and peak stress were calculated through the experimental complete stress-strain curves and the relationship between the mechanical properties and mass loss was explored.
28 citations
TL;DR: In this article, the artificial neural networks (ANN) method is employed to build a confinement model directly from experimental data to predict the different components of the stress-strain response.
22 citations
TL;DR: In this paper , the authors used particle swarm optimization (PSO) tech-nique to predict the strength of steel fiber reinforced concrete and found that the new stress-strain model predictions are consistent with the remaining 20% of the experimental stressstrain curves obtained.
Abstract: Several stress-strain models were used to predict the strengths of steel fiber reinforced concrete, which are distinctive of the material. However, insufficient research has been done on the influence of hybrid fiber combinations (comprising two or more distinct fibers) on the characteristics of concrete. For this reason, the researchers conducted an experimental program to determine the stress-strain relationship of 30 concrete samples reinforced with two distinct fibers (a hybrid of polyvinyl alcohol and steel fibers), with compressive strengths ranging from 40 to 120 MPa. A total of 80 % of the experimental results were used to develop a new empirical stress-strain model, which was accomplished through the application of the particle swarm optimization (PSO) tech-nique. It was discovered in this investigation that the new stress-strain model predictions are consistent with the remaining 20% of the experimental stress-strain curves obtained. Case studies of hybrid–fiber–reinforced concrete constructions were investigated in order to better understand the behavior of such elements. The data revealed that the proposed model has the highest absolute relative error (ARE) frequencies (ARE10 % and the lowest absolute relative error (ARE > 15 %) frequencies (ARE > 15 %).
21 citations
TL;DR: In this article , the artificial neural networks (ANN) method is employed to build a confinement model directly from experimental data to predict the different components of the stress-strain response.
21 citations
TL;DR: In this article , a neural operator-based framework, namely Fourier neural operator (FNO), was employed to learn the mechanical response of 2D composites and showed high-fidelity predictions of the complete stress and strain tensor fields for geometrically complex composite microstructures.
12 citations
TL;DR: In this paper , the replacement ratio of recycled coarse aggregate (r) has different influence on stress-strain relation of concrete with different strength grades, and the proposed model was benchmarked against available test results of 58 RAC specimens.
12 citations
TL;DR: In this article , experimental and theoretical studies were carried out to assess the influence of the shapes of dents in the tank wall on the stress-strain state of the defect zone.
Abstract: In the study, experimental and theoretical studies were carried out to assess the influence of the shapes of dents in the tank wall on the stress-strain state of the defect zone. By testing fragments of a cylindrical tank, it was found that the most appropriate expression is (5), which could take into account the leaching of the tank wall, resulting in a decrease in the stress concentration index. At the same time, during theoretical studies in this paper, it was found that polynomials determined the stress concentration coefficient, where the obtained analytical expression data were compared with the data determined numerically in the ANSYS program, and it was found that the spread was from 2% to 10%. According to the results of a numerical study of the stress-strain state of the dent zone in the tank wall, graphical dependences of the stress concentration coefficient on the dimensionless depth of the dent for various values of the dimensionless radius of the dents and do not exceed 2% of the indicators that are obtained. At the conclusion of the experimental and numerical studies, a conclusion was made about the degree of influence of the geometric dimensions of the dents on the stress concentration index.
10 citations
TL;DR: In this paper , the uniaxial stress-strain relationship of mixed recycled concrete (MRC), which composed of brick recycled aggregate (BRA), concrete recycled aggregate(CRA) and natural aggregate (NA), was studied under uni-axial compression.
TL;DR: In this article , the Smith-Watson-Topper model for all negative stress ratios was extended with Walker exponents, which can reproduce the higher mean stress effects in fatigue crack initiation observed in high-strength materials.
TL;DR: In this paper , the digital image correlation (DIC) technique has been adopted to accurately measure full-field strains generated in various quasi-static tension tests, including the cyclic tension test, the uniaxial tension test and stress relaxation test, and critical material properties of polydimethylsiloxane (Sylgard 184), which are directly related to the performance of wearable strain sensors, were accurately measured.
Abstract: Polydimethylsiloxane (PDMS), one type of silicone elastomers, has been widely used in the fabrication and prototyping of microfluidic and micro-engineering devices due to its high transparency, nontoxicity, and high chemical inertness. Considering its applications in precisely controlled conditions, e.g., wearable strain sensors, the mechanical properties of PDMS can critically influence the sensor performance. However, due to its viscoelastic properties and flexibility, the mechanical behavior of PDMS is generally difficult to measure accurately. In this study, the digital image correlation (DIC) technique has been adopted to accurately measure full-field strains generated in various quasi-static tension tests, including the cyclic tension test, the uniaxial tension test, and stress relaxation test, and critical material properties of PDMS (Sylgard 184), which are directly related to the performance of wearable strain sensors, were accurately measured. Experimental results indicate that the PDMS (Sylgard 184) elastomer exhibits very consistent and stable mechanical properties under quasi-static loading conditions, which is beneficial to the application of wearable strain sensors. However, the Poisson’s ratio, as a function of stain, needs to be carefully considered into this application.
TL;DR: The constitutive compressive stress-strain response of hybrid high-performance, fiber-reinforced concrete (HyHP-FRC) containing steel and polyvinyl alcohol (PVA) fibers is scarcely reported.
Abstract: The constitutive compressive stress–strain response of hybrid high-performance, fiber-reinforced concrete (HyHP-FRC) containing steel and polyvinyl alcohol (PVA) fibers is scarcely reported...
TL;DR: In this article , the authors considered the classification of steel cylindrical tanks failure from the action of seismic loads and revealed the physical and mechanical properties of the material and geometric parameters of the vertical tank.
Abstract: The paper considers the classification of steel cylindrical tanks failure from the action of seismic loads. Features of static calculation of tanks were revealed. Physical and mechanical properties of the material and geometric parameters of the vertical tank were determined. A full-size finite element model of a filled vertical steel tank has been developed. The calculation of the filled vertical steel tank was performed. The values of frequencies and periods of natural oscillations were obtained. Finite element method that was implemented in LIRA-multifunctional software package allows to design and calculate the structures for various purposes.
TL;DR: In this paper, a modification of the existing Johnson-Cook (J-C) model is proposed to incorporate the interacting effect of plastic strain and strain rate for 304 and 316 ASS.
Abstract:
In this study, tensile tests of 304 and 316 austenitic stainless steels (ASS) at various strain rates were performed to investigate the strain rate effect on tensile properties. It is shown that the strain rate effect on stress depends not only on the strain rate but also on the plastic strain level. Accordingly, a modification of the existing Johnson–Cook (J–C) model is proposed to incorporate the interacting effect of plastic strain and strain rate for 304 and 316 ASS. The proposed modified J–C model can reduce the difference from the experimental data at various strain levels, compared to the existing J–C model.
TL;DR: In this article , an autoencoder (AE)-shaped artificial neural network (ANN) model is designed to efficiently characterize the indenting load-displacement datasets, which are extracted into effective physically meaningful datasets by introducing a data post-processing procedure.
Abstract: The instrumented indentation technique has been investigated to efficiently evaluate the mechanical responses of materials with few limitations on the shape and size of the specimen. There have been attempts to discover a direct correlation between the stress-strain curve and the indenting load-displacement curve by introducing the concept of representative strain and stress. However, it is still difficult to find relible parameters and to distinguish similar load-displacement curves that correspond to different stress-strain curves with a limited number of experimental datasets. The present study introduces a finite element method (FEM)-based simulation that can output various load-displacement datasets corresponding to intrinsic properties of materials, including strain rate; these datasets are validated using experimental indentation results for diverse metallic materials at different indenting speeds (0.6, 0.9, 1.2 mm/min). In addition, an autoencoder (AE)-shaped artificial neural network (ANN) model is designed to efficiently characterize those datasets. Then, the indenting load-displacement datasets are extracted into effective physically meaningful datasets by introducing a data post-processing procedure. The proposed indentation FEM-AE-shaped ANN model demonstrates that a long-range true stress-strain curve can be attained even from a noisy experimental load-displacement dataset.
01 Apr 2022
TL;DR: In this paper , a transfer learning approach is introduced to predict stress-strain curves across different fiber reinforced polymer (FRP) composites fabricated via additive manufacturing, and the model achieved a mean absolute percentage error (MAPE) of less than 10%.
Abstract: The engineering stress–strain curve of a material allows one to determine mechanical properties such as elastic modulus, strength, and toughness. While machine learning has recently been used to predict stress–strain curves, large volumes of experimental data are required to achieve high prediction accuracy. More importantly, conventional machine learning models are not generalizable from one material to another. To address this issue, a novel transfer learning approach is introduced to predict stress–strain curves across different fiber reinforced polymer (FRP) composites fabricated via additive manufacturing. Optimal transport (OT) is integrated with the transfer learning approach by mapping the source label space to the target label space, which further improves knowledge transferability across different FRP composites. The stress–strain curves of the additively manufactured FRP composites are generated under flexural loading conditions. Experimental results show that the OT-integrated transfer learning approach can predict the complex stress–strain curves of FRP composites with small training data. The predictive model achieved a mean absolute percentage error (MAPE) of less than 10%. The extracted modulus and strength from the predicted stress–strain curves achieved MAPEs of less than 5% and 10%, respectively. This work demonstrates that transfer learning has the potential to transform how stress–strain curves are generated.
TL;DR: In this article, a structural modeling of TiB2/Cu composites is performed, in which the size, shape, position, volume fraction and proportion of the particles are numerically reproduced to be similar to those of the actual micro-structures of the composites and the ductile damage and failure behaviors for matrix, the elastic brittle failure for the particle reinforcement, and the traction separation for interface, were independently simulated in this model.
TL;DR: In this paper , the authors investigated the hybrid effects of carbon and polypropylene fibers on the stress-strain behavior of lightweight aggregate concrete (LWAC) under axial compressive load.
Abstract: This research aimed to investigate the hybrid effects of carbon and polypropylene fibers on the stress–strain behavior of lightweight aggregate concrete (LWAC). The considered test variables were two fiber volume fractions of 0.2% and 0.4% and two water/binder ratios of 0.27 and 0.30. Eighteen groups of prisms fabricated with fiber-reinforced LWAC were tested under axial compressive load. Experimental studies were carried out to analyze the influence of different fiber combinations on the complete stress–strain behavior. It was found that the carbon–polypropylene hybrid fibers led to toughness enhancement that was numerically more significant than the sum of individual fibers, indicating a positive synergistic effect between them. Finally, a mathematical expression of the stress–strain curve accounting for the fiber combinations was developed. Compared with existing stress–strain models, the proposed model shows better accuracy in predicting the effect of carbon and polypropylene fibers in both single and hybrid forms on the stress–strain curve of LWAC.
TL;DR: In this article, a new approach based on modified stress and strain with considering micromechanics and dislocation theory, has been extended to find the deformation mechanism during hot deformation of particulate metal matrix composite.
TL;DR: In this article , the authors investigated low-temperature mechanical properties of new constructional stainless steel (SS) QN1906Mo materials and welds and found that decreasing the temperature from 30 to -80 °C did not affect the ductility and elastic Young's modulus, but significantly increased yield and ultimate strength.
Abstract: This paper made efforts on investigating low-temperature mechanical properties of new constructional stainless steel (SS) QN1906Mo. Forty-two tensile coupons were firstly tensioned at four low temperatures of 30, -30, -60, and -80 °C. Environment for testing low temperatures was realized through an insulation chamber with injecting LNG. The test results reported low-temperature mechanical properties of SS QN1906Mo materials and welds. Test results showed that decreasing the temperature from 30 to -80 °C did not affect the ductility and elastic Young’s modulus of SS QN1906Mo material, but significantly increased yield and ultimate strengths of SS QN1906Mo material by 37% and 35%. Decreasing the temperature from 30 to -80 °C also exhibited equivalent increments in yield or ultimate for weld coupons to those material coupons but with much larger scatters due to the air voids in the weld coupons. Finally, this paper developed constitutive models to describe stress–strain laws of SS QN1906Mo at varying T range of -80 ∼ 30 °C, which were proved their capabilities. • Stainless steel (SS) QN1906Mo exhibited ductile failure mode at low temperatures ( T ). • Decreasing T from 30 to -80 ℃ did not affect elastic modulus of SS QN1906Mo. • Low temperatures significantly increase yield/ultimate strengths of SS QN1906Mo. • SS QN1906Mo provides larger yield and ultimate strength than SS 316L. • Developed constitutive models described well stress–strain behaviours of SS QN1906Mo at low temperatures.
TL;DR: In this paper, the performance of the interface bonding between carbon fiber-reinforced polymer (CFRP) and concrete was investigated under the combined action of sustained load and sulfate dry-wet cycles.
TL;DR: In this paper , a stress-strain model for rectangular reinforced concrete columns with corroded rectangular transverse reinforcement was proposed, which revealed that key variables such as corrosion degrees have significant influences on the maximum stress and the corresponding axial strain of specimens.
TL;DR: In this paper , the authors investigated the mechanical properties of rubberized concrete with volume replacement of coarse aggregate by rubber particles with size larger than 4 mm up to 100, which represent about 60-65% from total aggregate.
TL;DR: In this paper , the effect of biopolymer-treated soil on the onset of strain localization was investigated, and the results showed that biopolymers significantly improved the mechanical behavior of the soil.
Abstract: The enhancement of soil engineering properties with biopolymers has been shown recently as a viable and environmentally benign alternative to cement and chemical stabilization. Interest in biopolymer-treated soil is evident from the upsurge of related research activities in the last five years, most of which have been experimental in nature. However, biopolymers have not yet found their way into engineering practice. One of the reasons for this may be the absence of computational models that would allow engineers to incorporate biopolymer-treated soil into their designs. Therefore, the main goal of this study is to numerically capture a macroscopic stress-strain response and investigate the effect of biopolymers on the onset of strain localization. Several diagnostic strain-localization analyses were conducted, thus providing strain and stress levels at the onset of strain localization, along with the orientations of the deformation band. Several unconfined compression and triaxial tests on the plain and biopolymer-treated soils were modeled. Results showed that biopolymers significantly improved the mechanical behavior of the soil and affected the onset of strain localization. The numerical results were confirmed by the digital image analysis of the unconfined compression tests. Digital image processing successfully captured high strain concentrations, which tended to occur close to the peak stress.
TL;DR: In this paper, a quasi-static tensile fracture in nonlinear strain-limiting solids was investigated by coupling with the phase-field approach, which is consistent with the basic assumption of small strain.
TL;DR: In this paper , the influence of defects occurring in struts under tension, obtained using the additive method of laser powder bed fusion (LPBF), on the stress and strain distributions was analyzed.
Abstract: This paper describes the influence of defects occurring in struts under tension, obtained using the additive method of laser powder bed fusion (LPBF), on the stress and strain distributions. The study used struts of different thicknesses separated from Ti-6Al-4V diamond lattice structures. For numerical modeling of stress and strain fields, models that reflect the realistic shape of the tested struts with their imperfections were used. The shape of the diamond structure struts was obtained based on microtomographic measurements. Based on the results obtained, the influence of defects in the material structure on the stress and strain distribution was analyzed. It was observed that the main factor influencing the stress and strain distribution in the struts are micronotches on their external surface. These imperfections have a significantly greater impact on the stress and strain concentration than the micropores inside. Furthermore, the interactions of the imperfections are also important, which in turn affects the stress distributions and the formation of bands of high-stress values inside the material. The relationship between the presence of micropores, the stress–strain curves, and the mechanical properties of the material was also assessed.
TL;DR: In this paper, the mechanical properties of fiber-reinforced polymer composites produced by additive manufacturing technique (3D printing) and by traditional manufacturing techniques (compression molding) were investigated.
Abstract:
Composite products are often created using traditional manufacturing methods such as compression or injection molding. Recently, additive manufacturing (three-dimensional (3D) printing) techniques have been used for fabricating composites. 3D printing is the process of producing three-dimensional parts through the successful combination of various layers of material. This layering effect in combination with exposure to ambient (or reduced) temperature and pressure causes the finished products to have inconsistent microstructures. The inconsistent microstructures along with the oriented reinforcing fibers create anisotropic parts with difficulty to predict mechanical properties. In this paper, the mechanical properties of fiber-reinforced polymer composites produced by additive manufacturing technique (3D printing) and by traditional manufacturing technique (compression molding) were investigated. Three open-source 3D printers, i.e., FlashForge Dreamer, Tevo Tornado, and Prusa i3 Mk3, were used to fabricate bending samples from carbon-fiber-reinforced acrylonitrile butadiene styrene (ABS). Results showed that there exist significant discrepancies and anisotropies in mechanical properties of 3D-printed composites. First, the properties vary greatly among parts made from different printers. Second, the mechanical responses of 3D-printed parts strongly depend upon the orientations of the filaments. Parts with the infill oriented along the length of the specimens showed the most favorable mechanical responses such as Young’s modulus, maximum strength, and toughness. Third, all 3D-printed parts exhibit inferior properties to those made by conventional manufacturing. Finally, theoretical modeling has been attempted to predict the mechanical responses of 3D-printed products and can potentially be used to “design” the 3D printing processes to achieve the optimal performance.
TL;DR: In this paper , the effect of carbonation depth on peak stress, strain, elastic modulus, and the relative toughness of RAC was studied, and a uniaxial compressive loading test on the specimens was performed by using a mechanical testing machine.
Abstract: Highlights Uniaxial compressive stress–strain curves of recycled aggregate concrete (RAC) with different carbonation depth were investigated. The effect of carbonation depth on peak stress, strain, elastic modulus, and the relative toughness of RAC was studied. Stress–strain models of recycled aggregate concrete with different carbonation depths were established. Abstract The stress–strain relation of recycled aggregate concrete (RAC) after carbonation is very important to the assessment of the durability of RAC. The objective of this study is to investigate the uniaxial compressive stress–strain curves of RAC after carbonation. In this study, the specimens were prepared with 70-mm diameter and 140-mm height cylinders, and the carbonation of the specimens was accelerated after curing 28 days. Then a uniaxial compressive loading test on the specimens was performed by using a mechanical testing machine. The results show that the peak stress (σ0) and elastic modulus (Ec) of all specimens increase with the increase of carbonation depth. The ratio of ultimate strain to peak strain (εu/ε0) and relative toughness of the specimens decrease with the increase of carbonation depth. Furthermore, carbonation has a stronger effect on natural coarse aggregate concrete (NAC) than the 50% replacement rate of RAC with similar compressive strength. Stress–strain models of recycled aggregate concrete with different carbonation depths were established according to experimental results.