Increase In Deformation Rate Research Articles

An in-silico study on the mechanical behavior of colorectal cancer cell lines in the micropipette aspiration process

Cancer alters the structural integrity and morphology of cells. Consequently, the cell function is overshadowed. In this study, the micropipette aspiration process is computationally modeled to predict the mechanical behavior of the colorectal cancer cells. The intended cancer cells are modeled as an incompressible Neo-Hookean visco-hyperelastic material. Also, the micropipette is assumed to be rigid with no deformation. The proposed model is validated with an in-vitro study. To capture the equilibrium and time-dependent behaviors of cells, ramp, and creep tests are respectively performed using the finite element method. Through the simulations, the effects of the micropipette geometry and the aspiration pressure on the colorectal cancer cell lines are investigated. Our findings indicate that, as the inner radius of the micropipette increases, despite the increase in deformation rate and aspirated length, the time to reach the equilibrium state increases. Nevertheless, it is obvious that increasing the tip curvature radius has a small effect on the change of the aspirated length. But, due to the decrease in the stress concentration, it drastically reduces the equilibrium time and increases the deformation rate significantly. Interestingly, our results demonstrate that increasing the aspiration pressure somehow causes the cell stiffening, thereby reducing the upward trend of deformation rate, equilibrium time, and aspirated length. Our findings provide valuable insights for researchers in cell therapy and cancer treatment and can aid in developing more precise microfluidic.

Quantifying dislocation drag at high strain rates with laser-induced Microprojectile impact

As deformation rate increases, the thermally activated dislocation glide gives way to a continuous glide of dislocations governed by their interactions with phonons. Understanding the dislocation-phonon drag regime is critical for designing metallic materials for extreme deformations rates. However, it has proven challenging to study empirically, partly due to the resource intensive nature of the experimental approaches targeting this regime. Here, we develop an impression-based experimental approach combining laser-induced microprojectile impact (Hassani et al., 2020a) and spherical nanoindentation to characterize the dislocation-phonon drag regime. We also develop a physically based constitutive framework that, when integrated with our experimental measurements, can quantify the dislocation-phonon drag regime. We isolate the effect of dislocation-phonon drag by leveraging the similar deformation geometries and length scales but different operative mechanisms during spherical nanoindentation and microprojectile impact. We discuss mechanistic contributions to the plastic work for microprojectile impacts in a range of impact velocities producing strain rates up to 109 s−1. We also develop a deformation mechanism map focused on the transition from thermal activation to dislocation drag for a model FCC metal, copper.

Study of ordered phase precipitation behaviour and hardening mechanism of Au-20Ag-10Cu alloy during deformation-aging treatment

With the rapid development of aerospace technology, the demand for a longer service life of Au-Ag-Cu alloy as conductive slip rings is increasing. Therefore, it is important to improve the hardness of the alloys in order to prolong their service life. Deformation-aging can improve the hardness of many alloys. The effect of the deformation-aging process of Au-20Ag-10Cu (wt%) alloy was investigated on the microstructure and properties, which characterized by DSC(Differential Scanning Calorimeter), XRD(X-ray Diffraction), EBSD(Electron Backscatter Diffraction), TEM(Transmission Electron Microscope) characterization techniques, microhardness and electrical conductivity testing methods. The results indicated that the microhardness increases and the conductivity decreases gradually with the increase of deformation rate. As the aging time increasing, the content of face-centered tetragonal AuCu I ordered phase increases, and thus the hardness increases gradually. The maximum hardness value of 307.44 HV was obtained after undergoing 70 % deformation and then aged at 300 ℃ for 16 h with the electrical conductivity values of 8.40 MS·m−1. This result indicated that both higher hardness and higher electrical conductivity of Au-20Ag-10Cu (wt%) alloy could be obtained, which ensures the requirements in the field of electrical contact materials.

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.

Numerical study on the fire behaviour of restrained steel-concrete composite beams

An elaborate solid-shell finite element model was developed to investigate the fire behavior of restrained steel-concrete composite beams. The model was validated against experimental results in literatures. Parametric studies were also performed to study the parameters including restraint stiffness, load ratio, span, exposure length, embedding depth, steel beam height and protective layer on the fire behavior of restrained composite beam. The analysis results show that the mechanical response of restrained composite beams goes through four phases: elastic, elasto-plastic, rapid plastic deformation and plastic catenary action phase. With the decrease of restraint stiffness, the increase of load and span, the failure mode of the restrained composite beam changes from overall lateral instability to a sharp increase in deformation rate, and the code BS476-20 and ISO834 underestimate the fire resistance of restrained composite beams. The negative bending moment at the beam end increases sharply and reaches the peak value within a short fire time. Therefore, reinforcement shall be provided at the top of the concrete slab near the support section. Furthermore, the difference in fire resistance of restrained composite beams is mainly reflected in the plastic catenary action phase. When the load ratio is less than 0.5, the fire resistance of restrained composite beams can be improved by reducing the fire range, beam height and span, and increasing the axial restraint stiffness. When the load ratio is 0.7, the fire resistance of restrained composite beam is hardly affected by the axial restraint stiffness and span, while with the exposure length reducing from 5 m to 4 m, embedded depth increasing from 0 mm to 50 mm, and the protective layer increasing from 0 mm to 10 mm, the fire resistance of the composite beams increases by 114 min and 160 min and 76 min, respectively.

Microstructural and mechanical properties of hot deformed AISI 4340 steel produced by powder metallurgy

In this work, AISI 4340 steel was produced by powder metallurgy. Samples were sintered at 1150?C for 90 min. and then cooled in the furnace. Except to those in the as-sintered condition, one of the produced samples was homogenized at 1150?C for 1 h and then cooled in air. Other samples were deformed at the temperature range of 1150-930?C and deformation rate of 30 and 60% followed by cooling in sand, air and water mediums. The grain size gradually decreased depending on the deformation rate or cooling rate in AISI 4340 steel. Small grains occurred due to completely recrystallization at 60% deformation rate. Density and hardness also increased by the increase in deformation rate. The results showed that hot deformation is a process that is capable of improving the properties of AISI 4340 steel produced by powder metallurgy without rising the addition of alloying elements.

Characterization of cryo-rolled low carbon steel using ferrite-martensite starting microstructure

Cryo-rolling, a technique of severe plastic deformation (SPD) performed at cryogenic temperatures, has proven to be a promising technique for improving the microstructure and mechanical properties of low-carbon steels. Low carbon steel with a two-phase ferrite-martensite starting microstructure was subjected to cryogenic rolling at liquid nitrogen temperature to produce sheets with different deformation rates: 50%, 70%, and 90%. The microstructure, mechanical properties, and corrosion resistance were investigated. The results show that cryo-rolling effectively refines the microstructure and leads to a higher dislocation density and smaller grain size as the deformation rate increases. The cryorolled sample deformed at 90% has the highest grain aspect ratio (35.5), the smallest crystallite size (13.70 nm), the highest lattice strain (74.6 x 10-3), and the highest dislocation density compared to the samples deformed at 50% and 70%. This refined microstructure significantly improves the mechanical properties, with the cryo-rolled sample deformed at 90% exhibiting the highest hardness (152 HV), tensile strength (1020 MPa), and yield strength (950 MPa), corresponding to an increase of 175.6%, 344.0%, and 466.5%, respectively. In addition, cryo-rolling at 90% showed a decrease in corrosion resistance, with the lowest corrosion rate observed at 90% deformation (5.97 mm/year).

Investigation of Thermomechanical Processing of Nb Microalloyed Steel Produced by Powder Metallurgy

One of the most important properties of microalloyed steels is the different microstructures which are obtained by changing the thermomechanical processing parameters and steel composition. The control of microstructure such as grain size, precipitates, dislocation structure and inclusions are highly effective to determine the mechanical properties of microalloyed steels. The strengthening of mechanical properties can be done by thermomechanical processesing due to increase of nucleation sides via maximizing the austenite boundary and density of the deformation band. In this study, the unalloyed steel and microalloyed steel containing 0.15% Nb were produced by powder metallurgy and hot deformed to reduce the thickness by 40% and 75%. EDX analyzes, density, hardness and grain size measurements were also performed on specimens. According to the SEM microstructure results, the grain size gradually decreased with respect to the deformation rate in both steels. It was observed that small grains occurred due to a complete recrystallization process at 75% deformation rate which were supported by grain size analysis. The density and hardness values increased by the increase in deformation rate. While the density and hardness of microalloy steel under sintered conditions was 89.46% and 75 Hv, respectively, 75% deformed condition was 98.51 % and 231 Hv.

Effect of Deformation on the Microstructure of Cold-Rolled TA2 Alloy after Low-Temperature Nitriding

In order to improve the low hardness and poor wear resistance of TA2, this paper proposes a composite process of cold-rolling and low-temperature plasma nitriding with recrystallization. This composite modification process can effectively achieve the dual goals of modifying the matrix structure and surface of TA2 alloy simultaneously. The cold-rolling experimental results indicate that when the deformation rate increases, the small-sized grains in the sample increase significantly, and the grain orientation changes from TD (transverse direction) to RD (rolling direction) and then to TD. The nitriding experimental results indicate that the {0001} basal surface texture deflected from the TD direction to the RD direction, {10-10} cylindrical texture components gradually increased, and the special orientation phenomenon of cylindrical and conical texture disappeared, it can be seen that an increase in the deformation rate promotes recrystallization. The XRD test results indicate that after low-temperature nitriding, metastable nitriding phase TiN0.26 is formed on the surface of TA2. The SEM morphology of the cross-section shows that a relatively special nitrided zone is formed, and mechanical performance test results indicate the wear resistance and hardness of the alloy increased.

Study on Manufacturing Technology of Ag-8.5Au-3.5Pd Fine Alloy Wire.

The performance of Ag-8.5Au-3.5Pd alloy wire after cold deformation and annealing were analyzed by SEM (scanning electron microscope), strength tester and resistivity tester. The processing process and performance change characteristics of Ag-8.5Au-3.5Pd alloy wire were studied. The results show that alloy wire grains gradually form a fibrous structure along with the increase in deformation. The strength of the wire increases with the increase in deformation rate, but the increase trend becomes flat once the deformation rate is higher than 92.78%; the resistivity of Ag-8.5Au-3.5Pd alloy wire decreases with the increase in annealing temperature, reaching minimum (2.395 × 10−8 Ω·m) when the annealing temperature is 500 °C; the strength of Ag-8.5Au-3.5Pd alloy wire decreases with the increase in annealing temperature. When the annealing temperature is 500 °C, the strength and elongation of the φ0.2070 mm Ag-8.5Au-3.5Pd alloy wire are 287 MPa and 25.7%, respectively; the fracture force and elongation of φ0.020 mm Ag-8.5Au-3.5Pd alloy wire are 0.0876 N and 14.8%, respectively. When the annealing temperature is 550 °C, the metal grains begin to grow and the mechanical performance decrease; the φ0.020 mm Ag-8.5Au-3.5Pd alloy wire have good surface quality when the tension range is 2.5–3.0 g.

Effect of Deformation Rate on the Elastic-Plastic Deformation Behavior of GH3625 Alloy

GH3625 alloy is a typical polycrystalline material. The mechanical properties of a crystal within the alloy depend on the single crystal properties, lattice orientation, and orientations of neighboring crystals. However, accurate determination of single crystal properties is critical in developing a quantitative understanding of the micromechanical behavior of GH3625. In this study, the effect of deformation rate on the elastoplastic deformation behavior of GH3625 was investigated using in situ neutron diffraction room-temperature compression experiments, EBSD, and TEM. The results showed that the microscopic stress–strain curve included elastic deformation (applied stress, σ ≤ 300 MPa), elastoplastic transition (300 MPa 350 MPa) stages, which agreed with the mesoscopic lattice strain behavior. Meanwhile, the deformation rate was closely related to the crystal elastic and plastic anisotropy. The results of the lattice strain, peak width, and intensity reflected by the specific hkl showed that the deformation rate had little effect on the elastic anisotropy of the crystal, but had a significant effect on the plastic anisotropy of the crystal. With the increase in the deformation rate, the high angle grain boundaries gradually changed to the low angle grain boundaries, and the proportion of twin boundaries gradually reduced. Also, the grains transformed from uniform deformation to nonuniform deformation. Moreover, with the increase in deformation rate, the total dislocation density (ρ) of the alloy first decreased and then increased, whereas the geometrically necessary dislocation density (ρGND) monotonically increased, and the statistically stored dislocation (SSD) density (ρSSD) monotonically decreased. Meanwhile, the abnormal work hardening behavior of the sample at a deformation rate of 0.2 mm/min was mainly related to the SSD generated by uniform deformation. Additionally, the contribution of dislocation strengthening and TEM observation confirmed that the dominant deformation of GH3625 was dislocation slip, and its work hardening mechanism was dislocation strengthening.

Microstructure and texture evolutions in AZ80A magnesium alloy during high-temperature compression

In the process of thermal deformation, the microstructure and texture evolutions of AZ80A magnesium alloy have an important influence on its properties. In order to reveal the evolutions of microstructure and texture of AZ80A magnesium alloy during hot deformation, isothermal compression tests were performed on a Gleeble-3800 thermal simulator at a temperature range of 623 K∼723 K, a strain rates range of 0.001 s−1∼1 s−1, and a deformation rate of 20%∼60%. Based on the analysis of the true stress-true strain curves under the given deformation conditions, the hyperbolic sinusoidal constitutive model and dynamic recrystallization (DRX) kinetics model were established by regression method, respectively. The DRX behavior, microstructure and texture evolutions during the thermal compression were then analyzed by optical microscopy (OM) and electron backscattered diffraction (EBSD). The results show that an increasing deformation temperature and decreasing strain rate greatly support the development of DRX of AZ80A magnesium alloy. As the deformation rate increases, DRX of AZ80A alloy is gradually and more sufficiently developed, and the dominated deformation mechanism is gradually transformed from the {0001} base slip to {} cylinder slip. Moreover, the low-angle grain boundaries (between 5° and 75° in deformation rate of 20%) gradually transform into large-angle grain boundaries (between 50° and 90° in deformation rate of 60%). Besides, the texture is gradually transformed from a base texture paralleled to compression direction to a texture perpendicular to compression direction, where twinning, rather than slip, is the main deformation mechanism. The results in this study provides a guidance in the hot forming process of AZ80A magnesium alloy.

Effect of scandium alloying of filling wire on properties of welded joints of high-strength aluminum alloys

The results of the effect of scandium alloying of additive wires such as SvАМg4 and SvАМg63 on the structure and mechanical properties of welded joints of sheets and plates of 1420 alloy in mechanized single-passing and manual multi-pass welding are presented. It is shown that the introduction of 0.17...0.25 % scandium in the SvАМg4 and SvАМg63 filling wires contributes to decrease in the cracking rate and significant increase in the critical rate of deformation of the sample during welding on the МVТU sample. The level of microporosities and their location in multi-pass welding of plates of 1420 alloy depend on the magnesium content in the filling wire. The alloying of the SvАМg4 and SvАМg63 filling wires by scandium increases the ultimate strength of both the welding joint as whole and the weld metal.

Effect of Deformation on the Grain Size of the Ni3Al Intermetallic Compound Synthesized under Pressure

We have studied how the key parameters of a deformation process under the conditions of a bulk exothermic reaction of the formation of the Ni3Al intermetallic compound influence its grain size. The results demonstrate that the grain size of the intermetallic compound synthesized under pressure decreases with an increase in the time delay of exposure to pressure and an increase in deformation rate.

Microstructure Evolution of 316L Steel Prepared with the Use of Additive and Conventional Methods and Subjected to Dynamic Loads: A Comparative Study.

The mechanical properties and microstructure evolution caused by dynamic loads of 316L stainless steel, fabricated using the Laser Engineered Net Shaping (LENS) technique and hot forging method were studied. Full-density samples, without cracks made of 316L stainless steel alloy powder by using the LENS technique, are characterized by an untypical bi-modal microstructure consisting of macro-grains, which form sub-grains with a similar crystallographic orientation. Wrought stainless steel 316L has an initial equiaxed and one-phase structure, which is formed by austenite grains. The electron backscattered diffraction (EBSD) technique was used to illustrate changes in the microstructure of SS316L after it was subjected to dynamic loads, and it was revealed that for both samples, the grain refinement increases as the deformation rate increases. However, in the case of SS316L samples made by LENS, the share of low-angle boundaries (sub-grains) decreases, and the share of high-angle boundaries (grains of austenite) increases. Dynamically deformed wrought SS316L is characterized by the reverse trend: a decrease in the share of high-angle boundaries and an increase in the share of low-angle boundaries. Moreover, additively manufactured SS316L is characterized by lower plastic flow stresses compared with hot-forged steel, which is caused by the finer microstructure of wrought samples relative to that of additive samples. In the case of additively manufactured 316L steel samples subjected to a dynamic load, plastic deformation occurs predominantly through dislocation slip, in contrast to the wrought samples, in which the dominant mechanism of deformation is twinning, which is favored by a high deformation speed and low stacking fault energy (SFE) for austenite.

Damage identification of brick masonry under cyclic loading based on acoustic emissions

Ageing infrastructure, such as masonry railway bridges, suffers from structural deterioration due to fatigue loading. This paper presents an experimental study of brick masonry deterioration under gradually increasing cyclic loading with the aid of Acoustic Emission (AE) sensors. Two masonry beams were tested in the laboratory under similar stress conditions that masonry arches experience during train loading. An in-house AE monitoring system was developed for this study allowing both feature-based and waveform-based AE analysis. In the lab tests, different modes of damage were activated, such as tensile bond failure, brick and mortar crushing, diagonal shear failure and joint sliding. Feature-based AE analysis shows an increase in cracking rate before brittle failure events that is not necessarily accompanied by an increase in deformation rate. Statistical analysis reveals clear trends in AE results that correlate to different damage stages. The paper discusses how these findings can be leveraged to develop real-time structural alert systems that could provide early warning of damage before a significant increase in dynamic deformation occurs.

Mechanical Properties of PVB 3D Printed Output Fumigated with Ethanol

FDM 3D printing structures have rough surfaces and require post-treatment to improve the properties. Fumigation is a representative technique for removing surface unevenness. Surface treatment by fumigation proceeds by dissolving the surface of the protruding structure using a vaporized solvent. In this study, 3D printed PVB outputs are surface-treated with ethyl-alcohol fumigation. As the fumigation time increases, the surface flattens as ethanol dissolves the mountains on the surface of PVB and the surface valleys are filled with dissolved PVB. Through the fumigation process, the mechanical strength tends to decrease, and deformation rate increases. Ethanol vapor permeates into PVB, widening the distance between chains and resulting in weak bonding strength between chains. In order to confirm the effect of fumigation only, an annealing process is performed at 80 oC for 1, 5, 10, 30, and 50 minutes and the results of the fumigation are compared.

10 Effect of pulse current on micro-hardness and wear performance of cold-rolled T2 copper sheet

The effect of pulse current assisted rolling on the micro-hardness and wear properties of T2 copper sheet was studied. The micro-hardness of copper sheet with pulse current assisted rolling was measured, and the hardness values of the copper sheet at different deformation rates were obtained. The wear performance of rolled copper sheet was tested by friction and wear tester. The results show that compared with traditional cold rolling, with the increase of deformation rate, the micro-hardness of copper sheet with pulse current assisted rolling increased after an initial decrease. The micro-hardness reaches the minimum value((82.25 ± 2.5)HV0.1) when the rolling deformation rate reaches 65%. The specific wear rate of the copper sheet reached the maximum(0.00176 mm3/N · m) when the deformation rate of the copper sheet was 65%. The copper sheet has a smaller specific wear rate by using pulse current assisted rolling, and the oxygen element of the wear debris has a lower content. This indicates that pulse current assisted rolling can improve the wear resistance and oxidation resistance of copper sheet.

The Impact of Deformation Conditions on Divorced Eutectoid Transformation in Bearing Steels

The impact of deformation conditions on divorced eutectoid transformation (DET) is elucidated in bearing steels. The deformation experiments suggest that the effect of deformation on DET is two‐fold. In the case of large deformation reduction, the size of carbide particles is decreased, while the number density of deformation‐induced carbides is increased with increased deformation. When the deformation reduction is less than 30%, the degree of spheroidization is increased with increase of deformation reduction. Network carbides formed by M7C3‐type deformation‐induced carbides is obtained along prior austenite grain boundaries when deformation reduction is increased to 40%. Although the nature of deformation‐induced carbides is different from the carbides (M3C) formed by DET, the nature of spheroidized carbides after annealing continues to be M3C. With the increase of deformation passes, the number density of deformation‐induced carbides is increased. As regards the effect of deformation rate on DET, the degree of spheroidization decreases with the increase of deformation rate. The optimum condition is single‐pass deformation at 1073 K with a reduction of ≈30%. In this condition, only ≈0.5 h isothermal treatment at 993 K is adequate to complete the spheroidizing process, and the mean particle size after deformation is ≈0.2 µm.

Hot deformation behavior and Zener-Hollomon parameter constitutive model of Ti-22Al-26Nb-2Ta-0.5Y alloy

The thermal compression test of Ti-22Al-26Nb-2Ta-0.5Y alloy was performed using a Gleeble-3500 thermal simulator at deformation temperatures ranging from 900°C to 1150°C and strain rates ranging from 0.001s-1 to 10s-1. The results show that the flow stress of Ti-22Al-26Nb-2Ta-0.5Y alloy increases with the increase of deformation rate and decreases with the increase of deformation temperature. Based on the peak stress, the Arrhenius type constitutive model of Ti-22Al-26Nb-2Ta-0.5Y alloy was constructed using Zener-Hollomon parameters. The results show that this constitutive model has good prediction accuracy for peak stress. The correlation coefficient between the predicted value and the experimental value is R = 0.9922, the average relative error E is 8.36%, and the deviation within 15% accounted for about 96.67% of the total validation data points. This study provided a reference for the formulation of the hot working processing scheme for Ti-22Al-26Nb-2Ta-0.5Y alloy and the application of the Z-parameter constitutive model.