Results Of Tension Tests Research Articles

Synergistic effects of mediated by different 1,2-epoxybutane addition numbers butoxylated alkyl block alcohol ethers and SDS in mixed systems

In this study, nonionic surfactant butoxylated alkyl block ether (AE9Bn) and anionic surfactant sodium dodecyl sulphate (SDS) with different BO additions were mixed at different molar ratios to make a hybrid system. The interaction parameters and aggregation behaviors of the blended systems were investigated by observing the average direct particle drop distribution and microscopic aggregates in combination with the results of static surface tension tests of the blended systems. The diffusion process of the mixed systems was investigated using dynamic surface tension tests. The dynamic contact angle and foam properties of the solutions of the mixed systems were also studied. Finally, based on the experimental results, it was concluded that the mixed system of AE9Bn (n=2,5) and SDS formed a synergistic effect that significantly led to a decrease in CMC, with an increase in the number of BO additions leading to a more significant decrease in CMC. The mixed system is a non-ideal mixed system, which is consistent with the kinetic mechanism of mixing and diffusion. The hybrid system has good aggregation pattern and wetting diffusion behavior and has low foam stability due to slow maturation of Ostwald.

Indoor tests of sensor-enabled piezoelectric geocable–geogrid composite structure for slope rehabilitation and monitoring

Sensor-enabled piezoelectric geocables were combined with a geogrid to acquire a sensor-enabled piezoelectric geogrid (SPGG) based on the impedance–strain relationship. Tension, pullout, and straight shear tests were conducted on this SPGG configuration. The tension test results indicated that the tensile strain–normalized impedance curves were exponential in form within the first 7 % of strain and the rate of shift in impedance was independent of the tension loading rate. An excellent correspondence between the peak strength and impedance inflection point was observed in the results of the pullout and straight shear tests. Additional validation of the proposed SPGG was conducted through a collapse test of the reinforced soil slope model. The results indicated that the SPGG-obtained strains were similar to actual strain gauge measurements but provided a larger measurement range and that the SPGG was able to sense real-time vibrations during the slope collapse using a voltage analysis, confirming that the proposed SPGG can simultaneously provide soil reinforcement, strain monitoring of reinforcement materials, and vibration sensing. This research is expected to inform the development of a dynamic and static monitoring, large range, and accurate method for monitoring the conditions of reinforced soil over their entire lifecycles.

Radiation and thermal embrittlement of RPV steels: the links of embrittlement mechanisms, fracture modes and microcrack nucleation and propagation. Part 2. Strength and plasticity properties

The uniaxial tension test results are represented over wide temperature range for smooth round bars of 2Cr–Ni–Mo–V steel and A533 steel used for RPVs of WWER and PWR types. These steels are studied in the following states: (1) the initial (as-produced) state; (2) the thermally embrittled state modelling hardening mechanism of embrittlement; (3) the thermally embrittled state modelling non-hardening mechanism of embrittlement; (4) the irradiated state. The true stress-strain curves are determined over wide temperature range that is required for calculation of the stress-and-strain fields for various specimens. The true stress-strain curves for the investigated steels in the initial and thermally embrittled states are obtained when using standard mechanical characteristics. For the irradiated steels the true stress-strain curves are obtained when using the data of the digital video recording under continuous in-testing monitoring of the cylindrical parts of tensile bars. For the irradiated materials the procedure based on standard characteristics cannot be used as it is connected with very small strain. The procedure based on the digital video recording data is verified by comparison of the stress-strain curves obtained for the initial and thermally embrittled states on the basis of the digital video recording data and standard characteristics.

Anchors to solid clay brick masonry in tension: Behavior under monotonic and repeated loading for varied embedment depths

The paper presents the results of tension tests on anchors installed in solid brick masonry walls. Anchors were installed in various locations (either in bricks or in mortar joints), in walls either uncracked or with cracks passing through mortar joints. All tests, either monotonic or repeated, were executed under displacement-controlled conditions. The purpose of the experimental campaign was to investigate the behavior of anchors embedded to masonry under seismic conditions. To this aim, several parameters were investigated, namely, the depth at which anchors are embedded in masonry, their location within the wall, the presence of cracks, either crossing the anchor or being located at its vicinity. The measured tension resistances, depending on the examined parameters, are compared against values calculated based on current design guidelines. This comparison shows that the calculated values for the expected failure mode are sufficiently conservative.

A Stress‐Driven Double‐Phase–Field Framework for Tensile Fracturing Processes in Transversely Isotropic Rocks

ABSTRACTWe present a double‐phase–field framework for tensile fracturing processes in transversely isotropic rocks. Two distinct phase‐field variables are introduced to represent smeared approximations of tensile fractures along the weak bedding planes and through the anisotropic rock matrix, respectively. Driving forces that control fracture propagation in the phase‐field framework are constructed as a stress‐based formula with a recently developed tensile failure criterion that distinguishes the two failure modes in transversely isotropic rocks. For numerical implementation, we adopt a staggered integration scheme and decouple the governing equations so that the displacement field and phase‐field variables can be updated in sequence for a given loading step. The finite element formulation of the proposed framework is introduced in detail in this paper and is implemented in an in‐house finite element code. The numerical implementation is then validated by reproducing the uniaxial tension test results of Lyons sandstone. After that, we conduct simulations on a pre‐notched square plate loaded in tension to demonstrate the features of the proposed framework. Finally, we conduct simulations of three‐point bending tests of Pengshui shale and show that the proposed model can reproduce the force–displacement curves and failure patterns of specimens with different bedding plane orientations observed in laboratory experiments.

Investigating corrosion-induced deterioration in bolted steel plate joints using guided wave ultrasonic inspection

AbstractBolted steel plate joints encounter challenges posed by joint corrosion, which impact the quality of interfacial contact among the bolted components. Unfortunately, no correlation between corrosion-induced joint damage and preload, nor an existing numerical model capable of capturing such effects, has been identified. This study aims to utilize guided wave ultrasonic investigation to examine the deterioration of interfacial contact caused by corrosion in bolted joints. Additionally, a contact modification-based numerical approach is presented to capture the effects of changing interfacial stress during joint corrosion. Guided wave mode selection was conducted with some preliminary experiments supplemented with the theory of wave mode dispersion, hence leading to the selection of S0 and A0 mode existing at 300 kHz. The joint was then corroded in a controlled manner using an electrochemical process while simultaneous ultrasonic measurements were taken. The experimental observations highlighted the progressive dispersion in the transmitted A0 mode across the bolted joint, potentially due to changing interfacial stress boundaries between the plates. A damage parameter, termed the dispersion index, was developed based on the energy ratio of different signal sections. A linear change in the dispersion index was observed with the increase in corrosion-induced mass loss. The insight was further established through a numerical investigation by studying the effect of changing bolt preload and the corresponding interfacial stress distribution. The findings revealed that monitoring the changes in the stress distribution at the bolted interface can provide insight into interfacial corrosion. Eventually, destructive tension test results confirmed the effect of joint corrosion on the load-bearing capacity of the joint. The change in failure mode of the pristine and corroded specimen is observed. The reported approach establishes the potential of ultrasonic inspection to investigate the interfacial health of a bolted joint in corroding conditions.

Experimental study of rock fracture behavior under direct tension using three-dimensional digital image correlation

Understanding the mechanical characteristics of rocks when subjected to direct tension is crucial for assessing the stability of rock formations. Within the scope of this research, a series of tests was conducted using Tage tuff to assess the deformation behavior and crack extension of rock under direct tension. The axial, lateral, and shear strain fields as well as crack propagation, localized deformation behavior, and failure mode of the rocks were analyzed using three-dimensional digital image correlation method. The results showed that the axial strain fields on the specimen surface were heterogeneous, with different locations and localization occurring in the pre-peak stage, which was similar to the evolution of shear strain, whereas the lateral strain only showed slight changes. The crack extension direction was inferred, indicating that both tensile and shear stress occurred in the tests. Furthermore, different stress–strain responses were observed for the inside and outside of the localized bands. Then, the surface patterns of specimen failure were scanned and analyzed to assess the failure mode and residual strength of the specimen under direct tensile stress. Finally, the results of direct tension, uniaxial compression, and Brazilian split tests for Tage tuff were compared, and the complete stress–strain curve of uniaxial tension (UT) was simulated using a nonlinear-variable-compliance constitutive equation. This study provides a deeper understanding into the damage behavior of rocks under direct tension.

Application of Response Surface Methodology in the Formulation of an Eco-friendly Degreaser using Rhamnolipid Biosurfactant

Formulating a bio-based degreaser emulsion can be challenging because it requires maximizing the performance to be as good as a commercial chemical-based product without compromising the cost and effect on the environment. This study aimed to develop an eco-friendly degreaser using natural Rhamnolipid biosurfactant through response surface methodology (RSM), which was then validated and assessed compared to chemical-based commercial products. The Plackett–Burman design (PBD) and Box–Behnken design (BBD) were used to screen and optimize factors for the formulation. From the PBD's result, the amount of Rhamnolipid, with other environmentally friendly ingredients of D-limonene, sodium citrate, and calcium carbonate, were shortlisted as significant factors in the formulation. Next, the BBD optimization study revealed that only rhamnolipid and sodium citrate significantly affected the two-way interaction of the factor on the result of the surface tension and oil displacement test (ODT). In the validation study, the experimental value was very close to the rate predicted by the model for the response surface tension and ODT (24.14 mN/m and 241 mm, respectively). A comparison of the performance with commercial products proved that this formulation was comparable to that commercial product. Overall, this study revealed that the effective eco-friendly degreaser formulation was successfully produced using a minimal amount of rhamnolipid biosurfactant with a response surface methodology as a tool.

Investigating the quality of ethiopian steel reinforcing bars through comprehensive analysis

The fast economic growth, urbanization, and industrialization of Ethiopia led to the requirement for the establishment of various infrastructures and many residential building constructions consuming different types of materials. Reinforced steel bar is one of the most consumed construction materials in Ethiopia. The demand for reinforced steel bars in Ethiopia is satisfied by the local production and international market. However, most people lack trust to the use local products without justified reasons. This investigation work was done to evaluate the performance of the locally produced rebar concerning the Compulsory Ethiopian Standard (CES) to develop trust in contractors and consultants of different projects. A Compulsory Ethiopian Standard (CES) is an Ethiopian standard that has been prepared under the direction of the Technical Committee for Concrete and Concrete Products and published by the Ethiopian Standards Agency (ESA). Experimental works were done on rebar of grades B400BWR and B500BWR with different diameters collected from four different factories. The collected samples were investigated based on their yield strength, ultimate tensile strength, elongation, hardness, chemical composition, and microstructure formation of the product. The yield strength, ultimate tensile strength, and elongation of the rebar were analyzed based on the tension test results obtained from the 2000 KN Universal Testing Machine (UTM), and the chemical composition analysis was done using the Spark Emission Spectrometer Analyzer. The micro-hardness test was done using the Vickers Hardness Tester with 3kgf and 15-s dwell time at a 0.5 mm gap along the cross-section of the rebar. Microstructure analysis is done using EDX scanning electron microscope (SEM) and optical microscopy with different magnifications and resolutions on the cross-section of the rebar. From the tested samples one sample failed from B400BWR to achieve the minimum required yield strength of 400 MPa stated by CES 101, 2017. Samples of B500BWR satisfy all the requirements stated by the standard even if there is an increment up to 41 % beyond the minimum requirement.

Estimating the macro strength of rock based on the determined mechanical properties of grains and grain-to-grain interfaces

Obtaining complete rock cores is exceptionally challenging in certain extreme environments, such as deep earth and deep space; consequently, it is difficult to obtain the macro strengths of rock, which are the key indexes for engineering design, via standard rock mechanical tests. This research indicates that by determining and leveraging the mechanical properties of grains and grain-to-grain interfaces, the rock macro strength can be effectively estimated. Nanoindentation tests were first conducted to determine the elastic modulus of the mineral grains and their interfaces. Subsequently, symmetrical and anti-symmetrical four-point bending tests were executed to establish the statistical law governing interfacial tensile and shear fracture toughnesses. Furthermore, by employing the Dugdale–Barenblatt model and considering the oblique angular distribution of interfacial cracks, the corresponding tensile strength, shear strength, and friction parameter were derived. These meso‑mechanical parameters were then inputted into the 3D Finite-Discrete Element Method to estimate rock macro strength. And the numerical results were then compared with the results of standard uniaxial compression, direct tension, Brazilian splitting, and direct shear tests. The consistency observed between the predictions and experimental results attests to the validity of the proposed method.

Study on the Synthesis, Surface Activity, and Self-Assembly Behavior of Anionic Non-Ionic Gemini Surfactants.

The use of surfactants in oil recovery can effectively improve crude oil recovery rate. Due to the enhanced salt and temperature resistance of surfactant molecules by non-ionic chain segments, anionic groups have good emulsifying stability. Currently, there are many studies on anionic non-ionic surfactants for oil recovery in China, but there is relatively little systematic research on introducing EOs into hydrophobic alkyl chains, especially on their self-assembly behavior. This article proposes a simple and effective synthesis method, using 3-aminopropane sulfonic acid, fatty alcohol polyoxyethylene ether, and epichlorohydrin as raw materials, to insert EO into hydrophobic alkyl chains and synthesize a series of new anionic non-ionic Gemini surfactants (CnEO-5, n = 8, 12, 16). The surface activity, thermodynamic properties, and self-assembly behavior of these surfactants were systematically studied through surface tension, conductivity, steady-state fluorescence probes, transmission electron microscopy, and molecular dynamics simulations. The surface tension test results show that CnEO-5 has high surface activity and is higher than traditional single chain surfactants and structurally similar anionic non-ionic Gemini surfactants. Additionally, thermodynamic parameters (e.g., ΔG°mic ΔH°mic ΔS°mic et al. indicate that CnEO-5 molecules are exothermic and spontaneous during the micellization process. DLS, p-values, and TEM results indicate that anionic non-ionic Gemini surfactants with shorter hydrophobic chains (such as C8EO-5) tend to form larger vesicles in aqueous solutions, which are formed in a tail to tail and staggered manner; Negative non-ionic Gemini surfactants with longer hydrophobic chains (such as C12EO-5, C16EO-5) tend to form small micelles. The test results indicate that CnEO-5 anionic non-ionic Gemini surfactants have certain application prospects in improving crude oil recovery.

The Tensile Behavior of Hybrid Bonded Bolted Composite Joints: 3D-Digital Image Correlation versus Finite Element Analysis.

This study examines the behavior of hybrid bolted/bonded (HBB) joints loaded in tensile shear comprising plain weave carbon/epoxy laminates in quasi-isotropic (QI) and cross-ply (CP) layups. It proposes a combined approach of 3D digital image correlation and finite element analysis (FEA) to assess their behavior. To apply the FEA simulation accurately, a single layer of plain fabric was replaced with [0/90]s lamination. Experimental standard open-hole tension test results, as well as only bolted (OB) and HBB, along with FEA predictions, confirmed the accuracy of the substitution method. The FEA, calibrated by experimental results, provides insight into the distinctive characteristics of HBB joints in comparison with bonded and bolted joints. Critical considerations include material properties, damage modeling, adhesive characteristics, and mass scaling. The FEA results underscored the pivotal role of adhesives in HBB joints, rendering them akin solely to bonded configurations. HBB joints retain their geometry better than OB joints with considerably less out-of-plane displacement, following a sinusoidal trend. Moreover, the overall behavior of the two layups demonstrates that CP benefits from having higher strength than QI, especially at the critical hole located closer to the grip side.

Experimental investigations on tensile strength and fracture toughness of a polyoxymethylene fiber reinforced concrete

The crack resistance performance of concrete materials, characterized by tensile strength and fracture toughness, is vital for the durability and structural functionality of concrete components. In this study, polyoxymethylene (POM) fibers were added into concrete to enhance the crack resistance. Firstly, three-point-bending (3-p-b) tests and splitting tension tests were performed on notched beam and cubic specimens of plain concrete and POM fiber reinforced concrete. Then, considering the heterogeneity of concrete, the 3-p-b and splitting tension test results were analyzed to reveal the failure behaviors of plain concrete and POM fiber reinforced concrete materials. It was found that the addition of POM fibers was beneficial for improving the fracture resistance of concrete. The Boundary Effect Model (BEM) was used to estimate the tensile strength and fracture toughness of plain concrete and POM fiber reinforced concrete materials from the 3-p-b test results, which correlated well with those obtained from the splitting tension tests and the conventional method. Moreover, the influence of POM fiber length and volume fraction on fracture resistance was evaluated. Findings revealed that increasing fiber length and volume fraction effectively enhanced the tensile strength and fracture toughness of concrete material.

The performance transition of C/SiC composites induced by redistribution of residual stress

The residual stress generated from temperature changes and interference fit of rivet plays a significant role in the performance of C/SiC composites. To gain a thorough understanding of the residual stress evolution mechanisms and their influences on C/SiC composites, this work carries out comprehensive experimental research combined with simulation analyzes. The results of quasi-static tension tests present that as the environmental temperature rises from room temperature to 800 °C, the stiffness of structure increases a lot, while the strength of riveted joints significantly decreases. Furthermore, it is found that the microscopic failure modes are also changed. The cyclic unloading-reloading tests for calculating the residual stress quantitatively are conducted to explain the failure evolutions of structures. The obtained results reveal an important connection between the residual stress states and the microscopic failure modes of C/SiC composites. The environmental temperature and interference riveted joint both can affect stress state around the open hole, which are significant factors determining the damage modes and structural performance. In the process of C/SiC composites design, it is necessary to pay attention to the processing parameters of rivet interference fit to meet the performance optimization under service conditions.

Experimental and finite element analysis of Charpy impact, uniaxial tension and bending test of spin‐arc welded carbon steel 1018 plate

AbstractSpin‐arc welding process emerged as a continuation of gas metal arc or flux‐cored arc welding process, making use of filler wire and fuse plates of higher thickness with less welding defects. In this process, the filler wire is made to rotate along a central axis with a fixed diameter and frequency, thereby reducing the number of weld runs to join thick plates and resulting in increased productivity and less consumption of filler wire. American iron and steel institute carbon steel 1018 is a low carbon steel used primarily in rugged environments and is known for its excellent weldability and finds application in spacers, mounting plates, fixtures, carburized parts and machine parts. Present work aims to provide insight on experimental and finite element analysis of carbon steel 1018 (base and spin arc weld metal) specimens subjected to Charpy impact and uniaxial tension test. In order to verify the weld quality under bending load, a comparative study among experimental and finite element analysis of bending test is also performed. The finite element analysis results of Charpy impact, uniaxial tension and bending test are validated with experimental outcomes.

Experimental and numerical investigation on the dynamic shear failure mechanism of sandstone using short beam compression specimen

In this study, a novel testing method is proposed to characterize the dynamic shear property and failure mechanism of rocks by introducing the short beam compression (SBC) specimen into the split Hopkinson pressure bar (SHPB) system. Firstly, the stress distribution of SBC specimen is comprehensively analyzed by finite element method (FEM), and the results show that the optimal notch separation ratio of SBC specimen is C/H = 0.2 to achieve successful dynamic simple-shear tests. Then, dynamic shear tests are conducted on sandstone using the SBC-SHPB method. Via careful pulse shaping technique, the dynamic force balance is guaranteed for SBC specimens, and the testing results show that the dynamic shear strength of sandstone is significantly rate-dependent. Combining the results of dynamic compression and tension tests, the failure envelopes of sandstone under different loading rates are obtained in the principle stress plane. It is found that the failure envelope of sandstone constantly expands outwards with increasing loading rate. Moreover, the energy partition of SBC specimen is quantified by virtue of high-speed digital image correlation (DIC) technique. The results show that the kinetic energy portion is non-negligible, and the shear fracture energy increases with increasing loading rate. In addition, the microscopic shear cracking mechanism of SBC specimen is analyzed by the thin section observation: the intra-granular (TG) fracture of minerals dominates the dynamic shear failure of sandstone, and the portion of TG fracture increases with increasing loading rate. This study provides a convenient and reliable method to measure the dynamic shear property and failure mechanism of rocks.

The effect of dual thermomechanical processing paths on resulting microstructure and quasi-static mechanical properties of Mg-1Zn-0.2Ca

In this work, cast Mg-1Zn-0.2Ca (wt%) was thermomechanically processed using a two-step procedure to identify the impact of both processing steps on the resulting microstructure and mechanical properties. Samples were first preprocessed via rolling or conventional extrusion (at 400 °C), followed by Equal Channel Angular Extrusion (ECAE), utilizing routes A or Bc. ECAE was performed at 300 °C for the first pass, followed by 275 °C, 250 °C, and 225 °C for passes 2–4. Subsequent microstructures, textures, and quasi-static tension test results are presented to illuminate the effect of preprocessing and ECAE route on grain size refinement and mechanical behavior. Preprocessing via rolling yielded a smaller, more homogeneous initial grain size than the conventionally extruded material. After the second processing step, ECAE, the microstructural differences due to the preprocessing methods are reduced, but not eliminated, and mechanical properties show little variation between rolling and extrusion. The ECAE route did not impact the microstructural refinement, however, the 4Bc route did lead to enhanced ductility (>36%) and higher average ultimate tensile strengths, compared to the 4A route, when tested in the normal direction (perpendicular to the ECAE extrusion direction). The relative importance of texture alteration versus grain refinement and homogeneity is highlighted herein. Lastly, we comment on the influence of processing routes on inclusions and voids.

Triaxial tension and compression tests on saturated lime-treated plastic clay upon consolidated undrained conditions

Lime-treatment of clayey soil significantly increases its shear and tensile strengths. Consequently, the tensile strength of lime-treated soils deserves careful investigation because it may provide an appreciable benefit for the stability of earth structures. This study investigates the tensile and shear strengths of an untreated and lime-treated (3% of lime) plastic clay at different curing times (7 d, 56 d and 300 d), through triaxial tension and compression tests. Triaxial tension tests are performed using “diabolo-shaped” soil samples with reduced central section, such that the central part of the specimen can be under axial tension while both end-sections remain in axial compression. Consolidated undrained (CU) conditions with measurement of pore water pressure allow analyzing the failure conditions through effective stress and total stress approaches. The results of triaxial tension tests reveal that the failure occurs under tensile mode at low confining pressure while extensional shear failure mode is observed under higher confining pressure. Consequently, a classical Mohr-Coulomb shear failure criterion must be combined with a cut-off tensile strength criterion that is not affected by the confining pressure. When comparing shear failure under compression and tension, a slight anisotropy is observed.

Simulation of Wood Polymer Composites with Finite Element Analysis.

Wood is a cellulosic material that is most abundantly available in nature. Wood has been extensively used as reinforcement in polymer composite materials. Wood polymer composite (WPC) is an environmentally friendly and sustainable material exploited in building and construction within the marine, packaging, housewares, aerospace, and automotive industries. However, the precision of testing equipment for finding the properties of WPCs becomes less feasible compared to experimental analysis due to a high degree of differences in the measurement of properties such as stress, strain and deformation. Thus, evaluating the mechanical properties of WPCs using finite element analysis (FEA) can aid in overcoming the inadequacies in measuring physical properties prior to experimental analyses. Furthermore, the prediction of mechanical properties using simulation tools has evolved to analyze novel material performance under various conditions. The current study aimed to examine the mechanical properties of saw dust-reinforced recycled polypropylene (rPP) through experimentation and FEA. A model was developed using SolidWorks, and simulation was performed in ANSYS to predict the mechanical properties of the WPCs. To validate the obtained results, the simulated static tension test results were confirmed with experimental tension tests, and both assessments were well in accordance with each other. Using FEA to predict material properties could be a cost-effective technique in studying new materials under varied load conditions.

Selective Separation of Fluorite from Calcite Using Saponified Tridecanoic Acid as a Novel Collector

ABSTRACT Fluorite, as a vital calcium-containing mineral, usually coexists with calcite. When using the traditional collector sodium oleate (NaOL), froth flotation could not separate fluorite and calcite well on account of their similar surface properties. Meanwhile, a large amount of sodium silicate (SS) needs to be added to depress calcite, resulting in difficulties in tailings settlement and wastewater treatment. Therefore, a nontoxic and inexpensive surfactant saponified tricarboxylic acid (TA) was developed as a new collector. The flotation test results showed that TA had a higher selectivity for fluorite than NaOL, leading to the selective separation of both minerals. Zeta potential measurements indicated that TA was negatively charged and was strongly adsorbed on fluorite due to electrostatic interactions at pH 9.0. FTIR, XPS, DFT, and crystal chemistry calculations revealed TA had a stronger chemical interaction with fluorite due to its higher surface Ca activity and density, forming a TA-Ca complex through the bidentate coordination. In contrast, the interaction of TA with calcite could be ignored. In addition, the results of the surface tension and dynamic foam stability tests revealed that TA possessed the excellent foam performance. Therefore, these properties give TA excessive potential for industrial application and environmental protection in fluorite flotation.