Plastic Strength Research Articles

THE EFFECT OF QUICKLIME ON THE CBR VALUE OF SOFT SOIL STABILIZED WITH NICKEL SLAG AND ALUMUNIUM HYDROXIDE

The construction of road structures on soft soils is prone to structural damage due to the low bearing capacity of the soil under the load imposed by vehicles. Chemical stabilization is a popular method used to increase the bearing capacity of soft soils. This study aims to examine the effectiveness of soft soil stabilization using a mixture of lime, nickel slag, and aluminium hydroxide to enhance soil bearing capacity. The addition of lime as a binding agent is expected to reduce plasticity and increase soil strength, while nickel slag and aluminium hydroxide serve as additives that improve overall stabilization performance. The California Bearing Ratio (CBR) laboratory test was conducted by varying the proportions of stabilizing materials relative to the weight of the soft soil at its optimum moisture content. The lime addition variations used in this study were 2%, 4%, and 6%. The results showed that the lime, nickel slag, and aluminium hydroxide stabilization mixture significantly improved the soil's bearing capacity compared to untreated soil or soil stabilized only with nickel slag. The CBR value for soil stabilized with nickel slag, aluminium hydroxide, and lime reached 37.78% after 28 days of curing. This value is 7.6 times higher than that of natural soil and 1.3 times higher than soil stabilized with nickel slag alone. Thus, the use of a mixture of lime, nickel slag, and aluminium hydroxide is an effective method for increasing the bearing capacity of soft soils, making it applicable for road construction on soft soils requiring enhanced load-bearing capacity.

Blast Mitigation Using Monolithic Closed-Cell Aluminum Foam

Abstract Blast protection using cellular materials is being actively pursued at research and technology levels. The present work uniquely demonstrates the generation of stress waves, strain waves, and mass velocities in monolithic closed-cell aluminum foams of different densities and lengths, subjected to simulated blast loads, and their combined effect on blast attenuation. The foams were assumed to be resting against a rigid end wall. If the numerically calculated stress at the back face was found less than the applied stress at the front face, the interaction was termed blast mitigation or attenuation. The results show “pressure mitigation” to occur for low-density foams whose plastic strength is less than the applied pressure, but pressure amplification for high-density foams whose plastic strength is higher than the applied pressure. The pressure amplification observed in shorter-length high-density foams transformed to pressure mitigation if the foams were sufficiently long. Based on these results and other stress-, strain-, and velocity-related diagnostics, the underlying mechanism behind blast wave amplification/mitigation and its relation with foam density and length are proposed.

Comparing Machine Learning Models for Strength and Ductility in High-Entropy Alloys

AbstractWe compare several machine learning (ML) models that predict the yield strength and plasticity of high-entropy alloys (HEAs) for achieving high-accuracy with notably low root mean square errors (RMSE). Our models, developed using a comprehensive database of single-phase body-centered cubic (BCC) HEAs and BCC + B2 HEAs (where B2 is ordered BCC), integrate advanced feature engineering reflecting the current understanding of electronic factors, atomic ordering informed by mixing enthalpy, and the D parameter associated with stacking fault energy in HEAs. This approach enables systematic comparisons of different ML models, providing deep insights into the mechanical properties of BCC and related alloys. By leveraging genetic algorithms for feature selection and meticulous hyperparameter optimization, our ML framework excels in both predictive power and interpretability. The rigorous validation process includes repeated k-fold cross-validation and leave-one-out cross-validation (LOOCV), ensuring robust generalization. Moreover, our use of Shapley Additive Explanations (SHAP) revealed critical predictors such as the testing temperature-to-melting temperature ratio $$\left(\frac{{T}_{test}}{{T}_{melt}}\right)$$ T test T melt , the mixing enthalpy $$\left(\Delta {\text{H}}_{\text{mix}}\right)$$ Δ H mix and the D parameter, which play key roles in determining plasticity and yield strength. Our work represents an advancement in designing high-performance HEAs with optimized strength and ductility, offering a powerful tool for predicting mechanical properties and exploring new candidate alloys with exceptional mechanical behavior.

Multiscale modeling of thermo-hydromechanical behavior of clayey rocks and application to geological disposal of radioactive waste

This work is devoted to numerical analysis of thermo-hydromechanical problem and cracking process in saturated porous media in the context of deep geological disposal of radioactive waste. The fundamental background of thermo-poro-elastoplasticity theory is first summarized. The emphasis is put on the effect of pore fluid pressure on plastic deformation. A micromechanics-based elastoplastic model is then presented for a class of clayey rocks considered as host rock. Based on linear and nonlinear homogenization techniques, the proposed model is able to systematically account for the influences of porosity and mineral composition on macroscopic elastic properties and plastic yield strength. The initial anisotropy and time-dependent deformation are also taken into account. The induced cracking process is described by using a non-local damage model. A specific hybrid formulation is proposed, able to conveniently capture tensile, shear and mixed cracks. In particular, the influences of pore pressure and confining stress on the shear cracking mechanism are taken into account. The proposed model is applied to investigating thermo-hydromechanical responses and induced damage evolution in laboratory tests at the sample scale. In the last part, an in-situ heating experiment is analyzed by using the proposed model. Numerical results are compared with experimental data and field measurements in terms of temperature variation, pore fluid pressure change and induced damaged zone.

Effect of carbon on microstructure and mechanical properties of TiZrNb0.5V0.5 lightweight refractory high entropy alloy

The single-phase body-centered cubic TiZrNb0.5V0.5 lightweight refractory high entropy alloy exhibits good plasticity but poor strength. Therefore, C is added to this alloy to enhance its strength and improve its mechanical properties in this paper. The influence of varying C content on the microstructure, phase composition, and mechanical behavior of TiZrNb0.5V0.5C x RHEAs is investigated in detail. The results indicate that C addition leads to the dissolution of alloying dendrites and induces the formation of the FCC – MC carbides phase. The carbide volume fraction increases in proportion to the carbon content, thereby enhancing the alloy's yield strength and hardness. The yield strength increases by 36%, while the hardness increases by 39%. The physical parameters of the alloy are analyzed, which reveals that the introduction of C increases the alloy's electronegativity and atomic radius difference, thus promoting the formation of carbides.

Sedimentation characteristics of surficial sediments in Baiyun Canyon area, Northern South China Sea

The Baiyun Canyon area on the Northern Slope of the South China Sea is a potential hotspot for oil and gas resource development, but the sediment characteristics and sedimentary environment in this region present challenges for offshore engineering. This study comprehensively analyzed the physical, and mechanical properties of sediments in the area using geophysical exploration, engineering geological investigation, fixed-point sampling and hydrological observation. The engineering geological characteristics and sedimentary environment of surface sediments in the Baiyun Canyon area were studied, and the relationship between physical and mechanical properties and sedimentary environment was explored. The study revealed that the sediments in this area consist mainly of organic soft clay with high water content, low density, high pore ratio, high liquid limit, high plasticity and low strength. The physical and mechanical properties of the sediments vary, with the mechanical properties exhibiting higher variability than the physical properties. The research findings offer a scientific basis for understanding the seabed soil properties for designing submarine engineering structures in the deep waters of the northern South China Sea. This study holds significant theoretical and practical implications for oil and gas exploration and offshore engineering construction.

Plastic recovery and strength enhancement of pre-deformed AZ31B magnesium alloy using transient strong pulse current

Magnesium alloy components are mainly used in aerospace and automotive fields, but poor deformation ability at room temperature restricts their application in other industries. To address this issue, electrically-assisted technology is employed to enhance plasticity of alloys. However, conventional method weaken strength and intensify surface oxidation of such alloys because of prolonged action of current. In view of the above, pre-deformation (PF) treatment in combination with transient induced pulse current treatment (TIPCT) is proposed in the present work so as to balance between plasticity recovery and strength of AZ31B alloy. The results show that the total elongation of PF sample and the corresponding TIPCT specimen first increases and then decreases with the increase in PF percentage under the same voltage. At the same PF percentage, the total elongation of PF and TIPCT specimens also presents the same trend as the voltage increases. At the same time, the total elongation in PF and TIPCT specimens is greater than that of the as-received sample. The maximum total elongation is achieved at the PF percentage of 16 % and the voltage of 6 kV, being 35 % higher than that in the as-received sample. The improvement in total elongation is due to activation of more non-basal dislocations induced by TIPCT and the appropriate amount of microcracks generated by PF. In addition, the TIPCT process also improves the yield strength even if the PF percentage and voltage are changed. Besides that, the work hardening induced by PF treatment and instantaneous action of TIPCT process are the key factors enhancing yield strength. Moreover, comprehensive mechanical properties of TIPCT sample are found to outperform those after direct pulse current treatment (DPCT) under the same PF percentage. Therefore, the proposed composite process provides a feasible scheme to enhance strength and elongation of Mg sheets.

Stress relaxation aging of 7050 aluminum alloy under elastic and plastic loadings: A perspective from the geometrically necessary dislocations

Aerospace integral panels with large curvature often experience not only elastic loading but also plastic loading during creep age forming. However, the stress relaxation aging behaviors and mechanisms under loading stresses ranging from elastic to plastic regions, especially from the perspective of geometrically necessary dislocations (GNDs), have not been fully explored. The stress relaxation aging (SRA) behavior of 7050 aluminum alloy under elastic (200/250/300 MPa) and plastic loadings (350/400 MPa) are studied by uniaxial SRA, hardness and tensile tests, and corresponding mechanisms are clarified by Electron Back Scatter Diffraction (EBSD) tests and transmission electron microscopy (TEM) observations. Regardless of the loading stress, the stress relaxation of 7050 alloy shows a typical two-stage behavior (rapid stress reduction and stable stress relaxation rate). The second stage of stress relaxation under elastic loading shows an abnormal stress rebound, while the stress continuously decreases under plastic loading, and hardness and yield strength at 350 MPa are lower than that at 200 MPa during SRA. These results are attributed to strong dislocation pinning from small and dense precipitates at elastic loading and dislocations shearing large and sparse precipitates at plastic loading, respectively. Furthermore, both the stress reduction and its ratio increase with the increase of initial stress. GNDs contribute to the formation of low-angle grain boundaries (LAGBs) and accumulate at the LAGBs intersection to coordinate grain orientation for creep deformation. Compared to elastic loading, plastic loading promotes global growth of intragranular precipitates by elastic stress field and local heterogeneous nucleation and coarsening of precipitates at subgrain boundaries by more GNDs.

Dampak Penggunaan Abu Marmer terhadap Kuat Geser Tanah Lempung

Soil is an important part of the building structure because it has a function as a support for the building. Therefore, soil stability must be considered so that building construction is safe and durable. There are types of clay soils that have high plasticity values and low shear strength. Soils like this require stabilization with the addition of additives such as marble ash. The purpose of this study was to determine whether the addition of marble ash content has an optimal impact on improving the plasticity, density, and shear strength properties. The added material used was marble ash with a content of 3%, 6%, 9%, and 12% by weight of dry soil. The specimens were differentiated based on their curing age before being tested by triaxial. Based on the research results, it was found that the use of marble ash had the maximum impact on improving the plasticity properties and maximum density at an addition of 6%. This was followed by a significant increase in shear strength at the same addition. A good curing age for increasing the angle of internal friction in the soil was obtained at 14 days.

From Small Data Modeling to Large Language Model Screening: A Dual-Strategy Framework for Materials Intelligent Design.

Small data in materials present significant challenges to constructing highly accurate machine learning models, severely hindering the widespread implementation of data-driven materials intelligent design. In this study, the Dual-Strategy Materials Intelligent Design Framework (DSMID) is introduced, which integrates two innovative methods. The Adversarial domain Adaptive Embedding Generative network (AAEG) transfers data between related property datasets, even with only 90 data points, enhancing material composition characterization and improving property prediction. Additionally, to address the challenge of screening and evaluating numerous alloy designs, the Automated Material Screening and Evaluation Pipeline (AMSEP) is implemented. This pipeline utilizes large language models with extensive domain knowledge to efficiently identify promising experimental candidates through self-retrieval and self-summarization. Experimental findings demonstrate that this approach effectively identifies and prepares new eutectic High Entropy Alloy (EHEA), notably Al14(CoCrFe)19Ni28, achieving an ultimate tensile strength of 1085 MPa and 24% elongation without heat treatment or extra processing. This demonstrates significantly greater plasticity and equivalent strength compared to the typical as-cast eutectic HEA AlCoCrFeNi2.1. The DSMID framework, combining AAEG and AMSEP, addresses the challenges of small data modeling and extensive candidate screening, contributing to cost reduction and enhanced efficiency of material design. This framework offers a promising avenue for intelligent material design, particularly in scenarios constrained by limited data availability.

A comparative study of low cyclic loading effects on plastic strain, nonlinear damping, and strength softening in fiber-reinforced recycled aggregate concrete

The incorporation of fibers significantly enhances the properties and structural performance of recycled aggregate concrete. This study introduces Fiber-Reinforced Recycled Aggregate Concrete (FRAC) by integrating steel fibers (SF) and polypropylene fibers (PPF) into the recycled aggregate concrete (RAC) matrix. A comprehensive series of cyclic loading tests, including reload and unload sequences, were conducted to meticulously analyze the deterioration of strength and energy dissipation capabilities of SF/PPF-reinforced RAC. The research examines the effects of fiber characteristics, volume ratios, lengths, and diameters on strength degradation after the peak stress along the stress-strain curve. Degradation models based on plastic strain were proposed for both SF-reinforced RAC and PPF-reinforced RAC. The study further investigates the fluctuation of strain energy in FRAC under low cyclic loading, revealing the correlation between plastic strain energy and equivalent viscous damping ratio. A nonlinear viscous damping model that accounts for the influence of the reinforcing index (RI) is proposed. This model effectively predicts the degradation of strength, the evolution of plastic strain, and the dynamics of nonlinear viscous damping in composite materials with varying fiber content. Ultimately, this research provides essential technical insights for the practical engineering application of RAC.

Development of technology for functional prebiotic fondant candies using powder made of jerusalem artichoke pulp

The main disadvantage of most fondant candies is high sugar content and calorie content, low content of useful essential nutrients, rapid drying and staling during storage. It is relevant to use jerusalem artichoke pulp powder instead of sugar, which contains a significant amount of dietary fiber and minerals with high moisture-retaining properties. The introduction of jerusalem artichoke pulp powder in an amount from 5 to 9% contributes to: acceleration of the structure formation of the fondant mass due to the intensification of the sucrose crystallization process; to change the rheological properties of the fondant, namely, to increase its viscosity and plastic strength; to increase the dispersion of the fondant, while the proportion of sucrose crystals less than 20 microns in size in the fondant increases by 9–16%; to reduce the drying process of sweets during storage; to reduce sugar content, calorie content and increase nutritional value by increasing the content of dietary fibers and mineral substances. When using jerusalem artichoke pulp powder in an amount of 9% instead of sugar, it allowed to obtain functional fondant candies in terms of the content of soluble dietary fiber (31.5% of the daily requirement), which have a prebiotic effect. Compared with the control sample, the carbohydrate content in the experimental sample decreased by 8.1%, the calorie content decreased by 27 kcal, the potassium content increased by 42.9 times, calcium by 3.5 times, magnesium by 4 times, phosphorus by 12 times, iron by 8 times. Therefore, the use of this concentrator is advisable and promising from the point of view of improving the quality and increasing the nutritional value of the product, the developed technology of fondant candies using jerusalem artichoke pulp powder can be recommended for implementation in confectionery enterprises.

High strain-rate strength response of single crystal tantalum through in-situ hole closure imaging experiments

The properties of crystalline materials often depend on directionality and operating conditions. Specifically, the strength of materials can depend anisotropically on crystal direction and the loading condition. To probe these effects, a preliminary series of high strain-rate (>105/s) strength plate-impact hole closure experiments were performed on high purity single crystal tantalum cubes. The orientation of the single crystals with respect to impact/loading were varied to provide data to inform crystal plasticity modeling efforts. The experiments consist of in-situ high-resolution X-ray radiographic imaging of the hole collapse under dynamic compression conditions to infer the material strength via its resistance to closure at increasing levels of plastic strain. The experiments are compared against hydrocode simulation predictions. A comparison with simple elastic perfectly plastic strength model predictions is presented to elucidate the response of the different crystal orientations at high strain-rate and large plastic strains.

Development of an Energy-Efficient Method of Obtaining Polymer-Modified Bitumen with High Operational Characteristics via Polymer–Bitumen Concentrate Application

New requirements for the operational reliability of roads make the utilization of polymer-modified bitumen (PMB) more common in road construction. The application of polymer-modified bitumen based on traditional technology for the production of asphalt mixtures is associated with technological and economic difficulties and does not provide proper adhesion to the mixture’s mineral components. In addition, the method of producing a binder over a long time at high process temperatures leads to increased aging, which significantly reduces the service life of the material in the pavement. This paper presents the results of studies on the effect of polymer–bitumen concentrate (PBC) consisting of styrene–butadiene–styrene, plasticizer, and surfactant on the bitumen characteristics. It has been established that the use of PBC in the bitumen binder leads to an increase in the temperature range of plasticity, softening temperature, elasticity, and cohesive strength with a decrease in the viscosity of the modified bitumen. With a complex modifier rational content of 8% by weight of bitumen, the temperature range of plasticity is 79 °C, and elasticity is 82%, which exceeds the parameters of the factory PMB-60 based on SBS polymer. Tests of binders using the Superpave method allow classifying the modified binder to the PG 64-28, which shows an increase in the temperature range of viscoelastic properties by 6 °C compared with the binder produced by traditional methods. Thus, the expediency of using a complex additive containing a polymer and surface-active substances (surfactants) that can be distributed in bitumen without the use of a colloid agitator and plasticizer has been proven to improve the quality of an organic binder.

Learning dislocation dynamics mobility laws from large-scale MD simulations

By dispensing with all the atoms and only focusing on dislocation lines, the computational method of Discrete Dislocation Dynamics (DDD) gains greatly over Molecular Dynamics (MD) in simulation efficiency of metal plasticity. But whereas in MD dislocations follow natural dynamics of atomic motion, DDD must rely on a dislocation mobility function to prescribe how a dislocation line should respond to the driving force exerted on it. However, reflecting our still incomplete understanding of ways in which dislocations move, mobility functions presently employed in DDD simulations entail simplifications and approximations of limited or, worse still, unknown accuracy and applicability. Here we introduce a data-driven approach in which the dislocation mobility function is modeled as a graph neural network (GNN) trained on large-scale MD simulations of crystal plasticity. We apply our proposed approach to predicting plastic strength of body-centered-cubic (BCC) metal tungsten and show that, once implemented in a DDD model, our GNN dislocation mobility function accurately reproduces the challenging tension/compression asymmetry of plastic flow observed both in ground-truth MD simulations and in experiment. Furthermore, subsequently validated by MD simulations, the same function accurately predicts plastic response of tungsten under conditions not previously seen in training. By demonstrating its ability to learn relevant physics of dislocation motion, our DDD+ML approach opens a promising avenue to bringing fidelity of DDD models closer in line with direct MD simulations at a much reduced computational cost.

RETRACTED: Relationships among fall cone flow index and consistency identifiers of fine-grained soils with emphasis on toughness limit

It is well known that plasticity characteristics are one of the most important factors controlling the engineering behavior of fine-grained soils. In this regard, Atterberg limits are used for evaluation of plasticity and strength behavior of soils. Of all the plasticity identifiers, fall cone flow index, which is the slope of the flow curve is a descriptor of plasticity and undrained shear strength characteristics of cohesive soils. On the other hand, toughness limit is also efficient in prediction of many index properties of soils including plasticity characteristics, compression index as well as residual friction angle. This study is an attempt to establish relationships among fall cone flow index and consistency identifiers of fine-grained soils. Emphasis is given on toughness limit, which is believed to be a practical and efficient approach in assessment of fall cone flow index. Regression-based equations establishing relationships between fall cone flow index, plasticity index, plasticity ratio, toughness limit and liquid limit were presented. Besides, the efficiency of artificial neural networks in prediction of toughness limit and fall cone flow index was investigated. It should be noted that established relationships using regression equations are based on regional data, which come up with coefficient of determination (R2) values ranging between 0.706 and 0.978. On the other hand, ANN models were used to model global data, R2 values were obtained to be between 0.586-0.972 and 0.522-0.889 for training and testing phases, respectively. Relationships concerning local and global data were presented, along with analysis of effectiveness of application of relationships established for analysis of global data.

The Optimization of Avocado-Seed-Starch-Based Degradable Plastic Synthesis with a Polylactic Acid (PLA) Blend Using Response Surface Methodology (RSM).

This research improves the strength of plastic using avocado seed starch and PLA. The effect of blending avocado seed starch and PLA was optimized using the RSM approach by using two variables: water absorption and biodegradability. Mixing them using RSM gave the best result: 1.8 g of starch and 3 g of PLA. Degradable plastic has a tensile strength of 10.1 MPa, elongation at a break of 85.8%, and a Young's modulus of 190 MPa. Infrared spectroscopy showed that the plastic had a -OH bond at 3273.20 cm-1, 3502.73 cm-1, and 3647.39 cm-1, a CH2 bond at 2953.52 cm-1, 2945.30 cm-1, and 2902.87 cm-1, a C=C bond at 1631.78 cm-1, and a C-O bond at 1741.72 cm-1. The plastic decomposed in the soil. It was organic and hydrophilic. Thermal tests demonstrated that the plastic can withstand heat well, losing weight at 356.86 °C to 413.64 °C, forming crystals and plastic melts at 159.10 °C-the same as PLA. In the melt flow test, the sample melted before measurement, and was therefore not measurable-process conditions affected it. A water absorption of 5.763% and biodegradation rate of 37.988% were found when the samples were decomposed for 12 days. The starch and PLA fused in the morphology analysis to form a smooth surface. The RSM value was close to 1. The RSM gave the best process parameters.

High-temperature dependence of yield strength and microstructure in Ni54Fe19Ga27 and (Ni54Fe19Ga27)99.7B0.3 alloys

The deformation behavior, yield strength temperature dependence, and plasticity of the high-temperature L21(B2)-phase during compression in the temperature range 773–1173 K for Ni54Fe19Ga27 and (Ni54Fe19Ga27)99.7B0.3 shape memory alloys was determined for the first time. The studied alloys were characterized by high plasticity (over 70 %) and minimum yield strength level (13–65 MPa) at temperatures from 973 to 1173 K. Possible mechanisms of yield strength decrease, plasticity increase, and microstructure formation during the deformation process depending on test temperature and chemical composition are discussed. The possibility of hot rolling of Ni54Fe19Ga27 alloys at elevated temperatures was demonstrated.

Synergistic-strengthening strategy induce excellent electrical and mechanical properties in Cu/AlCrCuFeNi2.5 composites

A novel high-strength conductive Cu-based composite, utilizing AlCrCuFeNi2.5 (Ni2.5) high-entropy alloy particles as the reinforcing phase, is synthesized through a combination of ball milling and spark plasma sintering processes. The mechanical and electrical properties of the composites are optimized by adjusting the composition. Under the synergistic effect of multiple strengthening mechanisms, the fabricated Cu-20 wt% Ni2.5 composites achieve an exceptional compressive strength of 920 MPa while maintaining an electrical conductivity of 44.3 % IACS (International Standard Copper Standard). The establishment of robust interface bonding between Ni2.5 reinforcement and Cu matrix stands as a pivotal assurance for the holistic performance of composites. Ni2.5 HEA is distinguished by good plasticity and high strength compared with traditional brittle reinforcements. An insight into the differences brought about by the distinctive dual-phase structure in terms of interfacial bonding, crack propagation, and performance is provided. It paves the way for selecting and projecting the composites for electrical contact applications, ushering in a realm of fresh possibilities.

Improving strength-ductility synergy of twinning-induced plasticity steel by introducing a sandwich structure via submerged double-face friction stir processing

Twinning-induced plasticity steels typically exhibit remarkable plasticity and ultimate tensile strength, but the inferior yield strength has become a bottleneck limiting their application. In this work, a unique gradient sandwich structure that aims to break the bottleneck was successfully fabricated using a submerged double-face friction stir processing technique. The sandwich structure is composed of a coarse-grained zone in the core and two ultrafine-grained zones on the surfaces. An ultrahigh yield strength (1215 MPa) which is 2.2 times that of the as-received base material (543 MPa) is achieved for the sandwich structure. Additionally, significant elongation (19 %) and corrosion resistance are retained simultaneously. The coordinated deformation and effective strain transfer between the ultrafine-grained zones and coarse-grained zone facilitate the dispersion of stress and uneven deformation, which contributes to the excellent strength-ductility of the sandwich structure. This work provides a feasible method for fabricating high-performance steels.