Uniaxial Deformation Tests Research Articles

The Effect of Inulin Addition on Rice Dough and Bread Characteristics

Inulin may be widely used in in the food industry due to its many health benefits. It has the potential to increase the insufficient nutritional quality of gluten-free bread. Therefore, the aim of this study was to test the applicability of inulin in rice baking. The impact of added inulin (5%, 10%, 20%, 30%, and 40%) on the dough’s rheological, bread’s textural and sensory characteristics was evaluated. The extensibility of rice dough during uniaxial deformation tests (8.5 mm) was improved by the added inulin (10.2–12.3 mm). The presence of inulin softened the dough and shifted the gelatinization temperature toward higher values. The added inulin also increased the loaf’s specific volume (1.16–1.48 mL/g), tenderized the breadcrumbs, increased the crumb porosity (36–58%), and generally improved the crumb structure. The panelists favored the sensory characteristics of breads with inulin. However, baking losses were increased in these breads as well (15.1–18.5%). The effect of the added inulin on the dough and bread characteristics generally rose with an increasing addition of inulin, reaching the maximum in samples with 30% inulin. The presence of 40% inulin deteriorated some characteristics of the bread. Therefore, the addition of up to 30% of inulin seemed to be optimal for rice bread.

The Comparison of the Effect of Flour Particle Size and Content of Damaged Starch on Rice and Buckwheat Slurry, Dough, and Bread Characteristics

The effect of botanical origin, the flour particle size, and the content of damaged starch on flour pasting properties, dough behavior during a uniaxial deformation test, and bread characteristics were evaluated on rice and buckwheat flours. The rice flour with a median particle size D(0.5) of 60.2, 70.6, 106.8, and 189.4 μm, and buckwheat flour with a D(0.5) of 56.4, 68.4, and 95.8 μm were prepared using the same milling technology. The botanical origin of the flours was the strongest factor influencing the flour pasting properties, stress accumulated in dough during the uniaxial deformation test, loaf characteristics, texture, and sensory characteristics of breads. The flour particle size significantly influenced mainly the flour pasting properties. The effect of the content of damaged starch was the weakest among the studied factors. The flour particle size and the content of damaged starch were closely related. The flour botanical origin was the strongest factor; therefore, it seems not to be possible to predict the bread-baking potential of gluten-free flours based on the results obtained for flour of a different botanical origin. More research on flours from different plants prepared by the same milling process is required to support this hypothesis.

Microstructure and Macroscopic Characteristics of Powder Superalloy under Different Plastic Deformation Process Parameters

Through the uniaxial compression deformation test, this work focuses on analyzing the microstructure evolution of the alloy in the two stages of dynamic softening and strain hardening in the true stress-true strain curve during hot deformation, including grain size, local misorientation and The interaction of its relative mobility, and through the grain boundary orientation difference and grain orientation, explained the dynamic softening mechanism and strain hardening phenomenon, so as to find the microstructure-determining characteristic parameters of the dynamic recrystallization nucleation and core growth of the alloy and its evolution.

Influence of Deformation Rate on Nucleation and Growth of Recrystallized Grains during Hot Deformation of Nickel-Based Powder Superalloys

High temperature uniaxial compression deformation test was carried out on nickel-based powder superalloy FGH96 alloy by thermal processing simulation test machine, and the relationship between grain boundary characteristics and nucleation mechanism of recrystallized grains, growth characteristics of recrystallized cores and related dynamic softening mechanisms was studied. According to the correlation and evolution law of grains, combined with the change trend of grain orientation during the deformation process, the recrystallization behavior characteristics of the grains with special orientation generated during the deformation process were analyzed. When the deformation temperature is 1070 °C, the evolution rules of the substructure grain boundaries with an orientation difference of less than 10° are different under different deformation rate conditions, which indicates that the dynamic softening mechanism of FGH96 alloy is slightly different with the increase of deformation rate. There are different. With the increase of the deformation rate, the nucleation mechanism induced by Σ3 twinning gradually replaced the nucleation mechanism of continuous subgrain rotation and coarsening, and the grain growth rate gradually slowed down.

Grain Size Evolution of Nickel-Based Superalloys after Hot Deformation

In this work, the uniaxial compression deformation test of nickel-based powder superalloys was carried out in a vacuum isothermal adiabatic environment using the Thermocmaster-Z thermal processing simulation test machine. The evolution of the microstructure in the two stages of dynamic softening and strain hardening in the true stress-true strain curve in the process, including the interaction of grain size, local misorientation and their relative mobility. During most of the plastic deformation time, the flow stress is gradually increased, that is, the strain hardening dominates, while in the remaining plastic deformation process parameters, dynamic softening dominates. Under different plastic deformation process parameters, The average grain size fluctuates to a certain extent under the condition of partial strain values, but the final evolution law is gradually decreasing, while the final trend of the average local misorientation is increasing.

Calculation of Deformation-Related Quantities in a Hot-Rolling Process

The hot deformation of metal as a nonlinear system is mathematically described by a local linear model associated with the working conditions using a transfer function (TF) in the Laplace domain. Experimental data (true stress vs. true strain curves) are obtained using the established compressive uniaxial deformation test, where experimental conditions (strain rate and temperature) define the working conditions of the local linear TF model, which is intrinsically a function of strain. Based on the TF model, three important physical quantities of the tested metal are determined exactly: the work done per unit deformation, the average flow stress, and the flow-stress derivative with respect to the strain based on a particular TF. The exactly determined quantities, determined as a function of strain, can replace the previously used approximations in some rolling force and torque calculations.

Characterization of the material behavior and identification of effective elastic moduli based on molecular dynamics simulations of coarse-grained silica

The addition of fillers can significantly improve the mechanical behavior of polymers. The responsible mechanisms at the molecular level can be well assessed by particle-based simulation techniques, such as molecular dynamics. However, the high computational cost of these simulations prevents the study of macroscopic samples. Continuum-based approaches, particularly micromechanics, offer a more efficient alternative but require precise constitutive models for all constituents, which are usually unavailable at these small length scales. In this contribution, we derive a molecular-dynamics-informed constitutive law by employing a characterization strategy introduced in a previous publication. We choose silicon dioxide (silica) as an exemplary filler material used in polymer composites and perform uniaxial and shear deformation tests with molecular dynamics. The material exhibits elastoplastic behavior with a pronounced anisotropy. Based on the pseudo-experimental data, we calibrate an anisotropic elastic constitutive law and reproduce the material response for small strains accurately. The study validates the characterization strategy that facilitates the calibration of constitutive laws from molecular dynamics simulations. Furthermore, the obtained material model for coarse-grained silica forms the basis for future continuum-based investigations of polymer nanocomposites. In general, the presented transition from a fine-scale particle model to a coarse and computationally efficient continuum description adds to the body of knowledge of molecular science as well as the engineering community.

Rheological Characteristics of Model Gluten-Free Dough with Plantago Seeds and Husk Incorporation.

The seeds and husk of Plantago origin are rich source of dietary fiber known for its medicinal use. Despite the use of both Plantago psyllium and Plantago ovata products due to their physicochemical and nutritional properties, only the effects of Plantago ovata husk have been studied. Their structure-forming properties may positively affect gluten-free bread quality only if an adequate dough hydration is used. The aim of the work is to analyze the effect of different Plantago products: Plantago psyllium seeds and Plantago ovata seeds and husk in quantities of 3, 6 and 9% share on the rheological profile of model gluten-free dough and bread and bread’s technological quality and shelf-life. The rheological parameters of the dough were determined with Mixolab protocols and uniaxial deformation test. Bread quality and its textural profile analysis after cooling and storage were determined. The addition of Plantago psyllium seeds weakened the dough. All additives contributed to a reduction in starch retrogradation, bread hardness and water loss during baking, and to the improvement of the doughs’ resistance to extension, dough energy and bread yield. This influence is strongest when the Plantago ovata husk was used. However, the consumer acceptance of the tested breads was low and, in this respect, the breads with the addition of seeds of both Plantago psyllium and ovata were considered to be better than the husk.

Simulation of tectonic stress field and prediction of fracture distribution in shale reservoir

In this paper, a finite element-based fracture prediction method for shale reservoirs was proposed using geostress field simulations, uniaxial and triaxial compression deformation tests, and acoustic emission geostress tests. Given the characteristics of tensile and shear fractures mainly developed in organic-rich shales, Griffith and Coulomb – Mohr criteria were used to calculate shale reservoirs' tensile and shear fracture rates. Furthermore, the total fracture rate of shale reservoirs was calculated based on the ratio of tension and shear fractures to the total number of fractures. This method has been effectively applied in predicting fracture distribution in the Lower Silurian Longmaxi Formation shale reservoir in southeastern Chongqing, China. This method provides a new way for shale gas sweet spot optimization. The simulation results have a significant reference value for the design of shale gas horizontal wells and fracturing reconstruction programs.

Dynamic and static softening mechanisms of commercial-purity Zr during double-stage hot compressive deformation

The dynamic and static softening behavior of R60702 commercial-purity Zr was studied through single-stage and double-stage uniaxial hot deformation tests in the range of 600oC–800 °C. The microstructural evolution to uniaxial compression loading for the different conditions was investigated using a combination of optical microscopy and electron back-scattering diffraction (EBSD). The results show that the static softening fraction increases with an increase in temperature as well as holding time. At 600 °C, the peak stress of the second stage was greater than that of the single-stage, and the sample did not undergo static softening. At 800 °C, the peak stress of the second stage was less than that of the single-stage, and the sample underwent rapid static softening during holding time. As the holding time increased at 700 °C, the peak stress of the second stage of the sample decreased successively. At 700 °C and 1s holding time, the sample did not undergo static softening, and dynamic recovery and recrystallization occurred in the subsequent second stage. At 700 °C and 60s holding time, the sample underwent static recovery and recrystallization; larger grain growth and deformation appeared in the subsequent second stage. This change in the microstructural morphology with the flow stress curve is discussed in the subsequent sections.

Modelling approach for predicting the superplastic deformation behaviour of titanium alloys with strain hardening/softening characterizations

This paper introduces an approach for modelling the flow behaviour of different titanium alloys (VT6, OT4-1 and VT14 alloys by Russian specifications) in superplastic deformation temperature and strain rate ranges. The initial microstructure parameters () before starting the deformation test were included in the constructed model for each alloy. The investigated alloys have different initial microstructures and flow behaviour characteristics. The isothermal uniaxial tensile deformation tests were performed at the superplastic deformation temperature and strain rate ranges of each alloy. The VT6, OT4-1 alloys were characterized by strain hardening effect during the deformation test, while VT14 alloy was characterized by strain softening effect. A comparison study between the experimental and modelled data was performed. The general equation of the constructed models was affected by the flow behaviour of the investigated alloys. The comparison results proved the good capability of the constructed models to predict the flow behaviour of the studied alloys. The correlation coefficient R was 0.98, 0.95 and 0.97 for VT6, OT4-1 and VT14, respectively. The predictability of the constructed model was assessed by the cross-validation technique, which ascertained the quality of the constructed model.

Investigation of the Mechanical Behavior of Polystyrene using Molecular Dynamics

AbstractPolymer nanocomposites exhibit highly promising material properties caused by their molecular structure. Multiscale techniques are used to gain a deeper understanding of the influence of molecular mechanisms on the macro scale. Especially domain composition coupling approaches, e.g. the Capriccio method [1], require a precise match of the constitutive models of the coupled domains. To this end, in this contribution a methodology to characterize the material behavior of polymers using the widely used Molecular Dynamics approach is presented. Exemplary, polystyrene is investigated as a model system and the results of time proportional and time periodic uniaxial deformation tests as well as relaxation and creep tests are briefly discussed.

Study of uniaxial deformation behavior of 50 nm-thick thin film of gold single crystal using in situ X-ray pole figure measurements

In this paper, in situ measurements of synchrotron x-ray pole figure have been performed during incremental uniaxial deformation test on a single-crystal gold foil. The 50 nm thick Au thin film was elaborated by ion sputtering at 400 °C on NaCl single crystal as a template. The resulting film consists of a single-crystal gold foil containing a small density of thin and small {111} growth twins (few nm thick and few tens of nm long) revealed by x-ray pole figure measurement. The as-deposited gold single crystal was then transferred onto flexible polyimide substrates for deformation test. This work focuses on the relative evolution of the diffracting volume related to growth twins during a loading-unloading tensile test. Macroscopic applied deformations and x-ray pole figures were measured in situ during a uniaxial tensile test in the Au [110] direction. X-ray pole figures clearly evidenced the relative evolution of the diffracting volumes related to the (111) and 1¯1¯1 twins which exhibit a huge increase of about 450% at a uniaxial applied true strain of about 4%. The concomitant variation of diffracting volumes related to the two other twin variants (namely 1¯11 and 11¯1 twins) shows a relatively low decrease of 25%. The results open out onto a true strain-twinning volume hysteresis curve, indicative of the deformation mechanisms of gold thin films that can be interpreted as a twinning-detwinning mechanism.

Strain Rate-Dependent Viscoelasticity and Fracture Mechanics of Cellulose Nanofibril Composite Hydrogels.

In this work, the composite hydrogel toughening behaviors as manifested by strain rate-dependent viscoelastic properties and enhanced fracture mechanics, that is, suppressed catastrophic crack propagation with increased resistance, are systematically examined by using cellulose nanofibrils (CNFs) as fillers in the polyacrylamide (PAAm) matrix. The uniaxial deformation tests show that the tearing energy increases with crack velocity and becomes dominated by the viscoelastic energy dissipation in front of the crack tip. The creep dynamics of the composite hydrogels under a constant stress is examined, and the results indicate that the incorporation of the CNF pronouncedly suppresses the creep deformation. In addition, the microdeformation and failure mechanisms are analyzed through the observation of morphology of arrested crack tips and the damage zone by transmission electron microscopy and scanning electron microscopy. By aligning the CNF along the crack direction, it is possible to focus on the study of interfacial slip mechanics and identify the role of interfacial slip during the energy dissipation process. The results indicate that the CNFs are largely orientated parallel to the loading direction to maximize the energy dissipation, where the initiation of crack propagation is the primary fracture mechanism in composite hydrogels. The coarse feature on the composite fracture surface implies that the CNF initiates deflection of crack propagation fronts and thus increases the strain energy for continuation of the fracture. It is envisioned that with the incorporation of interdisciplinary strategies, one can rationally combine multiple approaches toward the creation of nanocomposite hydrogels with enhanced mechanical properties.

Characteristics of flour and dough from purple and blue wheat grain

The characteristics of flours and doughs prepared from wheat grains containing purple pericarp (variety PS Karkulka and Jumiko) and wheat grain containing blue aleurone (variety Skorpion) were tested and compared with commercial wheat to evaluate the applicability of colored wheat in bread making. The fine flours prepared from colored wheat grains significantly differed in the activity of the amylase enzyme, expressed as Hagberg falling number. Zeleny sedimentation volume of flour prepared from grains of the PS Karkulka variety (36 mL) was significantly higher than the values of AF Jumiko and Skropion (34 mL) varieties. The results of uniaxial deformation test indicated that doughs prepared from wheat varieties PS Karkulka and Skropion can be elongated; the dough is, however, weak and can be expected to rupture more easily than dough prepared from variety AF Jumiko, as well as commercial flour. Even if some variations in the values of farinographic dough development time and stability were also observed, clear differences in the behavior of doughs prepared from colored and commercial flours were not found. The differences in dough behavior during heating test were also negligible. It can be concluded that none of the tested colored wheat grains exhibited characteristics completely different from the others or the commercial one. The results may indicate the applicability of all tested colored wheat grains in yeast-leavened bread production.

Analysis of Mechanical Parameters and Creep Characteristics of Surrounding Rock in Fully Weathered Sandstone Tunnel

Based on the geological conditions of the fully weathered sandstone stratum in the expressway of the mountainous area, the Huizhou-Qingyuan section of the Yuzhan Expressway is used to analyze the mechanical parameters and creep characteristics of the surrounding rock of the tunnel through the indoor model test. It is concluded that: 1) The uniaxial compression deformation test measured the structural parameters of the fully weathered sandstone stratum structure, and obtained that the elastic modulus and internal friction angle φ of the fully weathered sandstone was 14.20°, and the cohesion c was 0.343Mpa. 2) The failure mode of fully weathered sandstone specimens was obtained by triaxial creep test. The creep curves of different weathered loads were analyzed and the Xiyuan rheological model was established. 3) The creep data was analyzed by MATLAB software, and the surrounding rock parameters under different surrounding rock were obtained.

Mechanical performance of polystyrene foam (EPS): Experimental and numerical analysis

In this work, we perform a series of tests to characterize the mechanical properties of polystyrene foam (EPS), including uniaxial compression tests, uniaxial tension tests and three point bending tests. EPS exhibits a ductile to brittle transition when the loading mode changes from compression to tension. The elastic modulus in tension is nearly one order larger than that measured in compression. The digital image correlation (DIC) technique is used to measure the strain distribution. A homogenous deformation can be observed in uniaxial deformation tests, where EPS exhibits a near-zero Poisson's ratio. For the three point bending tests, DIC can capture the strain localization behavior of specimens with a prefabricated crack. Based on the experimental observations, a simple phenomenological model is developed and further implemented for finite element analysis. The simulation results show reasonable agreement with experimentally measured strain distribution in the bending tests.

Interfacial-dislocation-controlled deformation and fracture in nanolayered composites: Toward higher ductility of drawn pearlite

The excellent combination of high strength and high ductility of drawn pearlitic steels is likely derived from the synergistic effects between the ferrite and cementite phases. However, the detailed mechanism, especially the mechanism responsible for the improvement in ductility, has not yet been fully elucidated. In this study, to achieve improved ductility of drawn pearlitic steels, interfacial-dislocation-controlled deformation and fracture in nanolayered composites of ferrite and cementite phases with the Bagaryatsky relationship are investigated via uniaxial tensile and compressive deformation tests using molecular dynamics simulations. Various modes of inelastic deformation are observed at the yield point according to the spacing of interfacial dislocations on the interface between the ferrite and cementite phases in the nanolayered-composite models. Spacing of the interfacial dislocations, which accommodates misfit strains between the ferrite and cementite phases, determines the phase stress and the interfacial dislocation structure in the nanolayered-composite models. This phase stress and interfacial dislocation structure influences the resolved shear/normal stress and the critical resolved shear/normal stress for each inelastic-deformation mode, respectively. Thus, interfacial dislocation spacings can control which inelastic deformation mode is activated at the yield point. We find specific interfacial dislocation structures on the ferrite–cementite interface that nucleate lattice dislocations with lower Schmid factors at the first plastic event. This interfacial dislocation structure can improve the ductility of drawn pearlitic steels because the high strain-hardening rate in the ferrite phases, resulting from the nucleation of dislocations with lower Schmid factors, is clearly expected to suppress the concentration of plastic deformation in the cementite phase [T. Ohashi et al., Mater. Sci. Eng. A 588 (2013) 214–220]. The possibility of the interfacial-dislocation-controlled deformation and fracture enabling higher ductility of drawn pearlitic steels is discussed.

Rock Mechanics Characteristics Test and Optimization of High-Efficiency Mining in Dajishan Tungsten Mine

Rock mechanics test is not only the basis for obtaining the mechanical parameters of rock but also an important means for studying rock mechanics and engineering. In this paper, the uniaxial compression deformation test, Brazilian splitting test, and cornea pressure shear test are carried out for rocks in the Dajishan tungsten mine. The basic mechanical parameters such as uniaxial compressive strength, tensile strength, elastic modulus, Poisson’s ratio, and internal friction angle of ore rock and surrounding rock are obtained. Meanwhile, damage characteristics of rock are deeply studied and analyzed under different experimental conditions. According to rock mechanics parameters which are obtained from indoor rock mechanics tests, three design schemes of stope structure parameters are optimized by using the FLAC3D numerical simulation software. On the premise of ensuring the stability of the stope structure, the recovery rate of ore and the production capacity of the stope are taken into consideration. It is suggested that the second scheme should be adopted for mines (18 m for ore room and 7 m for ore pillar), which provides scientific guidance for the safe and efficient mining of mines.

Effect of temperature on elastic properties of CNT-polyethylene nanocomposite and its interface using MD simulations.

This paper investigates the effect of temperature on the elastic modulus of carbon nanotube-polyethylene (CNT-PE) nanocomposite and its interface using molecular dynamics (MD) simulations, by utilizing the second-generation polymer consistent force field (PCFF). Two CNTs-armchair and zigzag-were selected as reinforcing nano-fillers, and amorphous PE was used as the polymer matrix. For atomistic modelling of the nanocomposite, the commercially available code Materials Studio 8.0 was used and all other MD simulations were subsequently performed using the open source code Large-Scale Atomic/Molecular Massively Parallel Simulator (LAMMPS). To obtain the elastic modulus of the nanocomposite, stress-strain curves were drawn at different temperatures by performing uniaxial deformation tests on the nanocomposite material, whereas the curvatures of the interfacial interaction energy vs. strain curves were utilized to obtain Young's modulus of the interface. In addition, the glass transition temperatures of the polymer matrix and nanocomposites were also evaluated using density-temperature curves. Based on the results, it is concluded that, irrespective of temperature condition, a nanocomposite reinforced with CNT of larger chirality (i.e., armchair) yields a higher value of Young's modulus of the nanocomposite and its interface. It was also found that, at the phase transition (from a glassy to a rubbery state) temperature (i.e., glass transition temperature), Young's moduli of the polymer matrix, nanocomposite, and its interface drop suddenly. The results obtained from MD simulations were verified with results obtained from continuum-based rule-of-mixtures.