Tensile Behavior Research Articles

Workability Investigation on the Fresh Mix of ECC Mortar and Crumb Rubber (CR)-ECC based on Variations of Palm Shell Ash, River Sand, and Cement

Engineered cementitious composite (ECC) is a composite that has better tensile properties and behavior than concrete. ECCs are usually made of cement, water, silica sand, cementitious materials, fibers, and other additives. The term ECC mortar is used because the ECC does not use fiber. The cementitious material in this research uses palm shell ash, with a proportion of 5%, 10%, and 15% of the cement weight. As a replacement for the fiber, crumb rubbers are used, with proportions of 2.5%; 5%; 7.5%; 10% and 12.5% of the cement weight. Workability was measured based on slumpflow tests (with measurements T500 and slumpflow diameter). The objective of this study is to establish the workability of fresh mix of the ECC mortar and CR-ECC with variations in the addition of palm shell ash, cement, sand and crumb rubber. Based on the results of slumpflow tests, the average diameter for fresh ECC mortars ranges between 88 cm to 106.5 cm, and the T500 ranges from 0.28 seconds to 1.39 seconds. As for fresh CR-ECC mix, the mean slumpflow diameter is between 71 cm to 93 cm and the T500 ranging between 0.90 seconds and 1.68 seconds. All of these values meet the slumpflow requirements stipulated by EFNARC. Nevertheless, the workability of the fresh mix ECC mortar is more flowable than the fresh mix CR-ECC. This is because crumb rubbers are water-absorbing.

Tensile and bond properties at elevated temperatures of a PBO-FRCM composite system for strengthening concrete elements: Experimental and analytical investigations

This paper presents experimental and analytical investigations on the tensile and bond behaviour at elevated temperature of a polypara-phenylene-benzo-bisthiazole (PBO) fabric reinforced cementitious matrix (FRCM) system for strengthening concrete elements. Direct tensile (DT) and single lap direct shear tests (DS) were performed under steady-state conditions at the following temperatures: 20 °C, 85 °C, 150 °C, 230 °C and 300 °C. The results obtained were evaluated in terms of strength, stiffness, ultimate strain, load vs. slip response at the interface PBO FRCM/concrete and failure modes. Overall, the tensile and bond properties were significantly affected by the temperature increase. These results are mainly associated with the reductions of mechanical properties of the FRCM constituent materials as well as the degradation of the interaction between the fibres and the inorganic matrix at elevated temperatures. The experimental results were then used (i) to evaluate the suitability of the Aveston–Cooper–Kelly (ACK) model in describing the tensile response of FRCM at elevated temperatures and (ii) to calibrate temperature-dependent local shear bond stress vs. slip laws for the FRCM-concrete interaction.

Tensile behavior of square-twist origami inspired mechanical metamaterials with soft joints and chirality applications

Abstract The performance and behavior of origami-inspired mechanical metamaterials are closely related to their structural design and the joints sub equivalent to the crease, in addition to material selection. Current research on square-twist origami focused on the unidirectional formation between its stable states. However, the complete process of squeezing-folding and stretching-unfolding as well as the mechanical behavior under tensile loading have not been thoroughly studied. In this study, square-twist origami mechanical metamaterials (STOMMs) with soft joints are proposed and investigated. The complete process of typical STOMMs from a flat state to folded stable state by extrusion folding and then returning to a flat state by stretch unfolding is explored using the finite element method. The strain energy and deformation characteristics of STOMMs are revealed at eight special stages during the folding, stable state, and unfolding processes. Additionally, the influence of geometric parameters on strain energy, deformation, and tensile behavior is also investigated. Finally, inspired by origami chirality, combinatorial mechanical metamaterials with self-locking/non-self-locking behavior are proposed and validated for their tensile and self-locking behavior. The studies could provide new content for origami-inspired soft joint mechanical metamaterials in terms of self-locking and load-bearing.

Bond stresses in post‐installed reinforcing bars derived via fiber optic sensors

AbstractA novel application of fiber optic sensing aimed at understanding the tensile behavior of post‐installed reinforcing bars in normal‐strength concrete is presented in this paper. To comply with established assumptions of cast‐in reinforcement, such as the uniform bond stress distribution, the design bond strength of post‐installed configurations is limited. In this study, pull‐out tests in confined conditions were conducted using two high‐performance mortars. Cast‐in‐place anchorages were tested for reference. The proposed fiber optic sensors and post‐processing techniques enable to continually measure and evaluate the bond stress distribution and monitor rebar deformation. Compared to cast‐in rebars, post‐installed rebars exhibit significantly higher bond resistance, particularly due to higher bond stresses at the beginning of the embedment length. These results highlight the potential for reducing the embedment length of post‐installed rebar. Moreover, variations in stiffness and bond stress distribution are found to significantly affect the slip and rebar deformation of both cast‐in‐place and post‐installed rebar.

Advancements and perspectives in engineered cementitious composites (ECC): a comprehensive review

Engineered Cementitious Composites (ECC) have garnered significant attention within the construction industry due to their exceptional mechanical properties and durability. This thorough review presents a meticulous analysis of the progress and prospects in ECC research. It commences by introducing the background and rationale for investigating ECC, while outlining the objectives of the review. The review provides an encompassing overview of ECC, encompassing its definition, characteristics, historical development, composition, and constituent materials. Emphasis is placed on the examination of ECC‘s mechanical properties, specifically its flexural behaviour, tensile behaviour, compressive strength, and resistance to environmental factors. Furthermore, the rheological properties of ECC, including workability, flowability, self-healing, crack mitigation, viscosity, and thixotropy, are discussed in detail. The review delves into the influence of fibre reinforcement on ECC, encompassing the types of fibres utilised, their impact on mechanical and structural properties, as well as fibre dispersion and orientation. Additionally, it explores the diverse applications of ECC across various fields, such as structural applications and sustainable building practices. The challenges and limitations associated with ECC, such as cost and availability, are addressed, alongside an exploration of future trends and research directions.

Effect of nozzle diameter and raster orientation on tensile and fracture behavior of FDM‐PLA specimens under mixed‐mode I/II loading

AbstractFused deposition modeling (FDM) is a material extrusion technique that works by extruding molten filament on a heated platform. In this method, several manufacturing parameters are engaged which affect the mechanical performance of printed parts. In this study, the effects of nozzle diameter on tensile (under two loading rates) and mixed‐mode I/II fracture behavior of printed specimens were examined. The obtained results revealed that testing speed had a minor effect on basic mechanical properties. For instance, ultimate tensile strengths of tensile specimens printed with 1 mm nozzle diameter were 32.56 and 39.71 MPa for test speeds of 1 and 5 mm/min, respectively. Higher nozzle diameters resulted in higher mechanical properties and fracture resistance (e.g., specimens printed with 45/−45° raster angle with 0.4 and 1 mm nozzle diameters indicated fracture loads of 4520 and 5071 N, respectively). Besides, fracture loads were predicted through the equivalent material concept coupled with J‐integral method.

Compressive and Tensile Behavior of High-Ductility Alkali-Activated Composites with Polyethylene Terephthalate Powder

Researchers have been engaged in the study of high-ductility concrete (HDC) due to its excellent ductility and cracking control ability. This study combines the concepts of HDC and alkali-activated composites (AAC) to develop high-ductility alkali-activated composites (HDAAC) using polyethylene terephthalate (PET) powder. Experimental investigations were conducted to assess the compressive and tensile properties of HDAAC, focusing on the impact of varying PET powder content (0%, 15%, 30%, and 45%) and fly ash/slag ratios (FA/GGBS, 6:4, 7:3, and 8:2). The results indicated that the compressive strength of HDAAC ranged from approximately 30 MPa to about 100 MPa, with the specimens maintaining good integrity after axial compression failure due to the bridging action of PE fibers. The replacement of quartz powder (QP) with PET powder slightly decreased the compressive strength and elastic modulus of HDAAC, albeit mitigating its brittleness under compression. An increase in GGBS content enhanced the compressive strength and elastic modulus of HDAAC due to the increased formation of the C-A-S-H reaction products, leading to reduced porosity and a denser microstructure. Under axial tension, HDAAC exhibited typical multiple-cracking behavior with significant pseudo-strain hardening. Increases in the PET content and FA/GGBS ratio resulted in finer cracks, indicating excellent crack control and deformation capabilities. The initial cracking strength, tensile strength, and ultimate tensile strain ranged from 3.0 MPa to 4.6 MPa, 4.2 MPa to 8.2 MPa, and 4.1% to 7.2%, respectively. Despite a decrease in the initial cracking strength and tensile strength with higher PET content, the ultimate tensile strain of HDAAC slightly increased. Observations under a scanning electron microscope revealed a distinct interfacial transition zone near the PET powder, leading to poor bonding with the alkali-activated matrix. In contrast, QP dissolved on the surface in highly alkaline environments, forming better interface properties. These variations in interface properties can be used to interpret the variations in the mechanical performance of HDAAC.

Effects and molecular mechanisms of jet ablation and fuel corrosion on separation failure of the asphalt-aggregate interface in airport asphalt pavements

To guide the improvement of asphalt pavement durability in airports, the effects and molecular mechanisms of jet ablation and fuel corrosion on separation failure of the asphalt-aggregate interface were investigated in this study using molecular dynamics simulations and density functional theory method. Firstly, tensile separation behaviors of the virgin, aged, and fuel-corroded asphalt-aggregate interfaces were simulated under different loading rates to evaluate their tensile strength and fatigue cracking resistance, and the experimental data were also used to verify the reliability of the simulation results. Subsequently, the molecular mechanisms of jet ablation and fuel corrosion on the separation failure of the asphalt-aggregate interface were analyzed by calculating the work of adhesion, work of cohesion, flowability parameters, and intermolecular binding energy. The results show that the aged specimen has higher ultimate tensile strength and fracture energy, but its flexibility and fatigue cracking resistance are significantly reduced. This is because the polar oxygen-containing groups generated during high-temperature aging enhance the intermolecular binding energy of the asphalt, but this also restricts the diffusion of asphalt molecules, resulting in greater frictional resistance and viscosity of asphalt during shear deformation, and thus loss of mobility and self-healing properties. On the contrary, since the light and medium oils soften and dilute the asphalt, and also weaken the intermolecular binding energy of asphalt, the fuel corrosion reduces the ultimate tensile strength and fracture energy of the asphalt-aggregate interface system, resulting in insufficient overall strength and load-bearing capacity.

Tensile behavior of polycarbonate: Key aspects for accurate constitutive modelling and simulation

Polycarbonate (PC) is a thermoplastic polymer used in many engineering applications such as safety devices and aerospace components. However, the unique behavior of PC under tensile load and its effects on the estimation of its constitutive curve are often overlooked in the literature, neglecting to consider crucial aspects of the characterization process. This work carries out a comprehensive analysis of the mechanical behavior of PC to understand the key points for accurate constitutive modeling and simulation of its static tensile performance, including its unconventional deformation mechanisms. The work starts from the accurate analysis of a representative experimental static tensile test on a rectangular section PC specimen and the evaluation of its true stress-strain curve. This analysis, carried out considering the classic length-based approach and the more accurate area-based approach, makes it possible to evaluate in detail the peculiar tensile behavior of this material. The mathematical form of the PC true stress-strain curve is then justified and the coincidence of the obtained length-based and area-based estimates of the same is demonstrated. Then, based on the in-depth understanding of the dynamics underlying the mechanical behavior of PC and making use of FEM simulations, the key points for obtaining its constitutive curve are defined. It is demonstrated that the constitutive curve is able to completely determine the behavior of PC, including its peculiar deformation mechanism. It is also highlighted which specific characteristics of the constitutive curve are critical in affecting various aspects of the material's behavior. The final constitutive curve of PC at hand is then obtained with an inverse approach, capable of accurately simulating all aspects of its tensile behavior. The validity of the proposed modelling key points is then confirmed, effectively explaining the underlying phenomena controlling the tensile behavior of PC and massively reducing uncertainty in the estimation of its constitutive curve starting from its area-based true curve.

GG20-GCI Brake Drum: The Effect of Mn/S on Machinability and Tensile Behavior

GG20-GCI Brake Drum: The Effect of Mn/S on Machinability and Tensile Behavior

Competition of systematically optimized deep neural networks for the estimation of tensile behavior of aluminum-magnesium alloy

Aluminum-magnesium (Al-Mg) alloys are prevalently employed within the aerospace sector. This research engaged a suite of deep learning approaches, encompassing the Artificial Neural Network (ANN), Gated Recurrent Unit (GRU) networks, Long-Short Term Memory (LSTM), and simple Recurrent Neural Network (RNN) to evaluate their predictive efficacy regarding the tensile strength and stiffness of Al-Mg alloys obtained from molecular dynamics simulation. The Taguchi method was initially applied to refine the architecture of each deep neural network (DNN), followed by a comparative analysis of their optimized configurations. The findings of this investigation revealed that the refined simple RNN and LSTM models exhibited superior predictive accuracy for estimating the strength and stiffness of the alloy, respectively. Moreover, the study elucidated that DNNs equipped with memory capabilities outstripped traditional ANNs in forecasting the tensile properties of Al-Mg alloys.

Inhomogeneity and anisotropy of Al-Zn-Mg-Cu alloy manufactured by wire arc additive manufacturing: microstructure, mechanical properties, stress corrosion cracking susceptibility

ABSTRACT In this study, Al-Zn-Mg-Cu alloy components were prepared using wire arc additive manufacturing (WAAM). Through multi-scale characterisation technology, performance testing and slow strain rate tensile (SSRT) testing, the microstructure, mechanical properties and stress corrosion cracking (SCC) susceptibility of WAAM Al-Zn-Mg-Cu components were studied, revealing the generation mechanism of inhomogeneity and anisotropy. The results show that with the increase of WAAM thermal cycles, the matrix precipitates (MPs), grain boundary precipitates (GBPs) and precipitation-free zones (PFZ) evolve in different paths and increase to varying degrees, resulting in performance decrease and increase in stress corrosion susceptibility, so the inhomogeneity is mainly attributed to differences in precipitated phases. The Inter-layer inclined to the scanning direction and the Inner-layer inclined to the building direction led to anisotropy in tensile strength and SCC behaviour, so the anisotropy is mainly attributed to the grain orientation and fracture mode.

Rate-dependent damage and failure behavior of lithium-ion battery electrodes

The mechanical properties and failure behavior of composite electrodes are critical to understanding the internal short circuits and ensuring the crush safety of lithium-ion batteries used in electric transportation. This study provides a comprehensive experimental investigation into the strain rate–dependent tensile/compressive behavior and failure mechanism of both anode and cathode, covering a range from quasi-static to dynamic conditions. A universal testing machine equipped with an industrial camera was used to assess the mechanical properties and observe the deformation process of the electrodes under quasi-static conditions. Additionally, a split Hopkinson bar system, coupled with a high-speed camera, was utilized to evaluate the mechanical properties and capture the deformation process of the electrodes under dynamic loading. The detailed deformation and failure modes of the electrodes were revealed by a combination of post-mortem characterization and images from high-speed cameras. The experimental results demonstrate a significant strain rate effect on the tensile and compressive mechanical behavior and failure mechanism of both anode and cathode. The rate dependence of tensile/compressive strength and failure strain were discussed, and the underlying mechanism for strain rate sensitivity was analyzed. The results and conclusions from this study provide an important foundation for the detailed modeling and failure prediction of lithium-ion batteries under impact loading. Further, these findings facilitate the safety design of electric vehicles by informing to enhance crash safety.

Achieving Excellent Strength–Ductility Synergy by Tailoring the Grain Size Distribution in a Metastable Austenitic Stainless Steel

Ultrafine/fine‐grained austenitic stainless steel (ASS) is prepared through severe cold rolling (CR) and subsequent annealing. The microstructure evolution and tensile deformation behavior is investigated, focusing on the influence of grain size distribution on the mechanical properties and strain‐hardening behavior of the ASS. In the results, it is revealed that obvious ultrafine/fine‐grained hierarchical microstructure forms after annealing at 650 °C for 80 and 110 min, respectively. And, the CR‐80 sample with more ultrafine grains (UFGs) (86%) exhibits good combination of strength and ductility. The yield strength (YS), ultimate tensile strength, and total elongation are 954 MPa, 1030 MPa, and 43.4%, respectively. The high YS mainly originates from the retained martensite and grain refinement strengthening, while the ductility enhancement can be attributed to the postponed transformation‐induced plasticity (TRIP) effect, which is a consequence of the significant number fraction of UFGs in the hierarchical microstructure. In this study, a new strategy is provided to solve the strength–ductility tradeoff in TRIP‐assisted metallic materials by tailoring the grain size distribution.

Notched Tensile Fracture of a Fe-15Mn-0.6C-2Al Twinning Induced Plasticity Steel at Room Temperature

The tensile fracture behavior of an Al-bearing TWIP steel was investigated by conducting a series of tensile tests on smooth and notched specimens with different notch geometries, focusing on the effects of evolution of the stress triaxiality and the effective strain during deformation. The flow curve and digital image correlation (DIC) analysis evidenced suppression of dynamic strain aging due to Al addition, and therefore, the effects of local inhomogeneous deformation associated with Portevin-Le Chatelier (PLC) band on fracture could be excluded. The smooth specimen fractured with negligible necking despite the absence of PLC bands. As a result, the effective strain was uniform through the gage section and the stress triaxiality (<i>η</i>) of ~0.33 was nearly unchanged over the entire cross-section up to the maximum load. This led to the fracture surface of the smooth specimen being entirely covered with fine equiaxed dimples. For notched specimens, the fracture strain was drastically reduced with decreasing notch radius, indicating the high notch susceptibility of the steel. The effective strain of the notched specimens was the highest at the edge of the notch root, regardless of the notch radius, so cracks first developed at the surface of the notch root. Although the <i>η</i> at the center of the notched specimens (0.40~0.48 depending on the notch radius) was higher than that of the smooth one, the center of the fracture surface of all notched specimens exhibited dimple features that were very similar to the smooth one, even in size. In contrast, in spite of the same <i>η</i> of ~0.33, fractography at the edge of the notched specimens revealed a fracture mode transition from dimple fracture to void sheet fracture to quasi-cleavage fracture as the notch radius decreased. The present results were rationalized in terms of the local evolution of stress triaxiality and effective strain during deformation, which were analyzed using the finite elemental method and DIC technique. It can be said that the fracture mode of TWIP steel, showing limited necking, was more influenced by the distribution and/or gradient of stress traiaxiality and effective strain rather than their local absolute values - that is, the severer their gradient is, the easier the quasi-cleavage fracture occurs.

Tensile Deformation Behaviors and Microstructure Evolution Under Various Temperatures for MAR‐M247 Nickel‐Based Superalloy

The study aims to analyze the tensile behavior and microstructural changes in MAR‐M247 nickel‐based superalloy across different temperatures. Tensile behavior is examined under a constant strain rate of 2.5 × 10−4 s−1 at varying temperatures. Results indicate a temperature‐dependent nature of the alloy's tensile properties. At 550 °C, a Portevin–Le Chatelier effect is observed, attributed to twinning nucleation and carbon atom diffusion. Dynamic recrystallization occurs at 950 °C, manifesting in a sinusoidal stress–strain curve. At room temperature, the primary fracture mechanism involves dislocation shearing in the γ matrix, with minor dislocation shearing in the γ′ phase. At 550 °C, carbides along grain boundaries and the γ′ phase impede dislocation motion. Concurrently, dislocations shear the γ′ phase, leading to the formation of superlattice intrinsic stacking faults and Kear–Wilsdorf locks, thereby enhancing tensile strength. However, at 950 °C, dislocation motion primarily involves climb, carbides decompose, the γ′ phase softens and enlarges, resulting in a notable decrease in tensile strength.

Tensile, flexural, and mode-I cracking behavior of interpenetrating phase composites (IPC), developed using additively manufactured PLA-based structures with different infill densities and epoxy resin polymer as matrix

Interpenetrating phase composites (IPC) materials are designed to combine the advantages of made-from materials or develop an intended behavior. Recently, the use of 3D printed structures has received attention due to advantages, such as the rapid and cheap prototyping techniques of complex structures. However, most materials, such as polylactic acid (PLA) used for conventional 3D printing, have low strength and insignificant durability. To overcome these issues, the excellent characteristics of polymer adhesives, such as epoxy resin, can be used to increase their strength and durability. In this paper, PLA-based 3D printed samples and epoxy resin adhesive were merged to develop an interpenetrating phase composite. The samples were printed with 25, 50, 75, and 100 infill percentages and tested in direct tensile, bending, and mode-I fracture. From the results, it can be seen that reducing the infill percentage to 75, 50, and 25 % reduces the tensile strength to 16, 9, and 3 MPa (−40 %, −66 %, and −90 % compared to the sample with 100 % infill with 26 MPa strength), adding epoxy resin to develop an IPC, results in 24, 29 and 32 MPa tensile strength. Compared to 3D-printed parts with the same infill percentages, the IPCs have 150, 320, and 1140 % higher tensile strengths, respectively. Also, the failed samples were reviewed by scanning electron microscope.

Investigation of Temperature Dependency of Tensile and Fatigue Behavior of Manganese-Molybdenum-Nickel ASTM A302 Grade C Alloy

Investigation of Temperature Dependency of Tensile and Fatigue Behavior of Manganese-Molybdenum-Nickel ASTM A302 Grade C Alloy

Additively manufactured Ti‐6Al‐4V microstructure tailoring for improved fatigue life performance

AbstractIn this study, laser powder bed fusion (LPBF)‐produced Ti‐6Al‐4V is subjected to three separate post‐build heat treatments (HTs), specifically (1) a one‐step annealing HT exceeding the ‐transus temperature, (2) a two‐step annealing HT whose first step exceeds the ‐transus temperature and the second step is an anneal below the ‐transus temperature, and (3) a sawtooth HT with temperatures oscillating below the ‐transus temperature. Tensile properties and fatigue crack growth behavior were assessed and compared to wrought Ti‐6Al‐4V. LPBF materials nominally exhibited a 17% yield stress reduction, 1.9% strain‐to‐failure increase, and 9.2% modulus of toughness decrease. Fatigue crack growth curves were used to assess the linear crack growth rate region and approximate fracture toughness (). Post‐mortem fractography observed striations indicating the crack growth direction frequently changes direction providing an understanding of the slower crack growth rates observed in LPBF materials compared to their wrought counterpart.

The Role of Molybdenum on Room Temperature Tensile Behavior of Recrystallized Fe30Mn5Al1CxMo Lightweight Austenitic Steels

The Role of Molybdenum on Room Temperature Tensile Behavior of Recrystallized Fe30Mn5Al1CxMo Lightweight Austenitic Steels