Effect Of Deformation Rate Research Articles

The effect of deformation rate on the process of hot extrusion with dispensing of round hollow semi-finished products

Background. Stamping of round hollow semi-finished products by hot reverse extrusion is one of the initial operations in the manufacture of hollow products for special purposes. The force and shape change of the metal during hot plastic forming is significantly affected by the deformation rate or the speed of movement of the deforming tool. For special-purpose products, certain mechanical properties are required in the wall height and bottom part. The wall height properties are ensured at subsequent stretching transitions with thinning of the semi-finished product obtained by hot extrusion, which involves working out the metal structure by plastic deformation to achieve the required properties. Therefore, it is an urgent task to study the effect of the deformation rate on the force and shape change of the metal during hot reverse extrusion of hollow semi-finished products.Goal. To determine the influence of the deformation rate on the parameters of hot reverse extrusion with the dispensing of hollow semi-finished products from round and square billets by means of finite element method (FEM) modeling and to compare the results of theoretical researches.Methodology of implementation. Theoretical researches of extrusion power modes, specific forces, and the stress-strain state of metal were carried out by modeling using the FEM in the DEFORM software environment.Results. The FEM was used to model the process of hot reverse extrusion with dispensing of round hollow semi-finished products from mild steel with protrusions at the end of the bottom part on the side of the cavity and on the outer surface. The deformation rate was in the range of 20 to 80 mm/sec. Round and square cross-sectional blanks were used. The dependence of the extrusion force on the punch displacement was determined. The distribution of specific forces on the deforming tool was determined. The stress-strain state and temperature distribution in the deformed metal at the end of extrusion were determined. The development of the metal structure by hot plastic deformation was evaluated and the results obtained were comparedConclusions. The effect of the deformation rate on the parameters of hot reverse extrusion with dispensing of round hollow semi-finished products was determined

Simulation of hydrogen embrittlement of steel using mixed nonlocal finite elements

A new simulation strategy to model hydrogen embrittlement based on a multi-field finite element using displacements, pressure, volume variation, nonlocal damage variables and lattice hydrogen concentration as unknowns is proposed. The material is described using a modified GTN model, which includes the description of hydrogen enhanced decohesion (HEDE). The finite element problem is solved using a fully implicit formulation. Numerical problems related to volumetric locking are solved using a mixed pressure/volume variation formulation. The use of the mixed formulation allows a straightforward evaluation of the pressure gradient, which drives hydrogen diffusion. Mesh size dependence is solved using an implicit gradient nonlocal formulation. Two variables are used to represent damage: the plastic volume variation and the accumulated plastic strain, controlling nucleation. The model is used to simulate an existing experimental database (Moro et al., 2010; Briottet et al., 2012) including tensile, fracture toughness and pressurized disk tests. The model, after adjusting the various coefficients, can represent the main experimental findings: the effect of deformation rate on the failure of tensile specimens, the transition from surface to internal fracture with increasing deformation rate, the sharp toughness drop under hydrogen (CT specimen), the fracture location and the effect of the pressurization rate in the case of the tests on disks.

Study of the effects of deformation rate and adhesive layer thickness under impact loading on parameters of adhesive joints in a vehicle

BACKGROUND: At the present time, new technologies of joints adhesive joints are used more and more widely along with spot welding in domestic and foreign vehicles. Study of the joint strength and the influence of deformation rate and the adhesive layer thickness under impact loading on the parameters of the joint in a vehicle is a relevant technical task.
 AIMS: Study of the influence of deformation rate and the adhesive layer thickness on the adhesive joint parameters (strength, deformation, etc.) under impact loading as well as evaluation of the efficiency of the proposed modified calibration method for the adhesive layer model on the example of tubular structure, which is often used in the strength elements of a vehicle.
 METHODS: Experimental studies were carried out with impact loading at the speed of 6.66 m/s (the axial im-pact) and 6.87 m/s (the side impact) with the mass of 22.3 kg. Simulation of operating conditions was performed in the LS-Dyna software that made possible to study the stress-strain states (SSS) of adhesive-bonded tubular structures and to estimate the simulation error.
 RESULTS: Based on experimental and calculated results, the length of the adhesive layer failure under the impact loading in the steel structures bonded with the Henkel EP 5055 adhesive is shorter in the joints with the 0.5 mm thick adhesive layer than in the joints with the 1 mm thick adhesive layer. The total deformation of the bonded structure at the side impact loading for the 1 mm thick adhesive layer is less than for the 0.5 mm thick layer, as the adhesive layer absorbs some of the energy. For the axial impact loading, the differences are insignificant. Errors of adhesive joint simulation under impact loading have been reduced significantly (by 15%) with using the proposed modified method of calibrating the adhesive layer properties considering the influence of the deformation rate and the adhesive layer thickness in the finite element model.
 CONCLUSIONS: The practical value of the study lies in the proposed modified model, considering the influence of the deformation rate and the adhesive layer thickness under impact loading on the joint parameters and making possible to improve simulation accuracy, as well as in recommendations for the best value of adhesive joint properties in adhesive-bonded vehicle structures.

Effect of Deformation Rate on the Microstructure and Drawability of Medium-Carbon Steel

Effect of Deformation Rate on the Microstructure and Drawability of Medium-Carbon Steel

Effects of Deformation Rate on the Mechanical Properties of an Industrial Al-Zn-Mg-Cu Alloy

The deformation parameters of aluminum alloys during thermal deformation have a significant impact on the alloy's properties. The industrial free forging of the Al-Zn-Mg-Cu alloy was carried out at deformation rates of 10 mm/s and 20 mm/s, respectively, at a deformation temperature of 430°C and a deformation degree of 60% in this study. The microstructure was determined using EBSD, and the mechanical characteristics were examined. According to EBSD observations, the recrystallization fraction of the alloy is nearly identical under both deformation rates; however, the average grain size of the alloy with a deformation rate of 10 mm/s is 10.8 μm larger than that of the alloy with a deformation rate of 20 mm/s. As the deformation rate increased from 10 mm/s to 20 mm/s, the alloy's yield strength and fracture toughness increased. The resistance to fatigue crack propagation, on the other hand, displayed the reverse pattern. That is, the alloy with a 20 mm/s deformation rate had a higher FCP rate than the alloy with a 10 mm/s deformation rate. In summary, the influence of deformation rate on the microstructure and mechanical properties of a high alloy Al-Zn-Mg-Cu alloy was investigated.

Effect of deformation rate on the axial joint strength made of Fe-SMA

Iron-based shape memory alloys (Fe-SMA) have been applied to structural members, such as pipelines and curved pipes, for underground structures due to their excellent properties. However, in the case of an earthquake or high winds, the resulting impact force causes a bending and twisting behavior in joints of the pipe. For this reason, a clear understanding of the relation between the deformation rate and joint strength is strongly needed. In this work, the specimen of a joint which a round bar made of SUS304 is tightened by a hollow cylinder made of Fe-SMA was prepared by first expanding the cylinder at a constant quasi-static rate and heating it up to the austenitization temperature. Then, a push-out test, which a compressive-shear combined force acts, was conducted at various deformation rate including the impact level to evaluate the axial joint strength. The results scientifically demonstrate that the axial strength would show the negative sensitivity with respect to deformation rate. However, when the deformation rate exceeds 8.3 mm/s, positive rate sensitivity can be found. This work may provide us with a systematic understanding of the deformation behavior of joints made of Fe-SMA and the safety design of the product.

Revealing Layer‐Specific Ultrastructure and Nanomechanics of Fibrillar Collagen in Human Aorta via Atomic Force Microscopy Testing: Implications on Tissue Mechanics at Macroscopic Scale

Soft biological tissues are natural biomaterials with structures that have evolved to perform physiological functions, for example, conferring elasticity while preserving the mechanical integrity of arteries. Furthermore, the mechanical properties of the tissue extracellular matrix (ECM) significantly affect cell behavior and organ function. ECM mechanical properties are strongly affected by collagen ultrastructure, and perturbations in collagen networks can cause tissue mechanical failure. It is thus crucial to understand the ultrastructural mechanical properties of soft tissues. Herein, the ultrastructural and nanomechanical properties of arterial tissues are reported. Specifically, maps of aorta tissue stiffness in its three constitutive layers, namely tunica intima, media, and adventitia, are reported. Atomic force microscopy (AFM) with large and ultrasharp tips is used to explore tissue stiffness at two scales. Quasistatic tensile tests are further conducted to understand a potential correspondence between small‐scale mechanical properties obtained via AFM indentation and macroscopic behavior of the tissue at low and large strains. Furthermore, gradients in stiffness across the various layers as well as deformation rate effects are investigated. It is envisioned that the established methodology serves as a tool to investigate the effect of ECM remodeling associated with vascular diseases such as aneurysms and arterial stiffening linked to hypertension.

A rate dependent cohesive model for the analysis of concrete-FRP bonded interfaces under dynamic loadings

Reinforced concrete structures, strengthened with fibre-reinforced polymers materials (FRP), are frequently subjected to dynamic loadings, due to, e.g., earthquake, blast, or impact events. The definition of proper cohesive laws to model the bond between the fibre-reinforced polymer sheet and concrete, under high deformation rates, is a crucial issue because the typical failure mode of these joints is debonding of the composite from the concrete substrate. Although numerous studies have already investigated the quasi-static interface response, experimental and numerical investigations, concerning the effect of deformation rate on the bond behaviour between a fibre-reinforced polymer sheet and concrete, are still few. This paper presents a cohesive law for the modelling of interfaces under mixed-mode dynamic loadings, considering the effect of deformation rate. The formulation is based on the decomposition of the discontinuity displacement vector across the interface into elastic and viscoplastic components, with the evolution of the latter being governed by a viscoplastic law formulated according to the overstress approach. Experimental results available in literature, related to double- and single-lap shear tests, performed on FRP reinforced concrete specimens, are exploited to validate the proposed model and to show its capacity to simulate closely the experimental behaviour.

High-entropy alloys: Structure, mechanical properties, deformation mechanisms and application

The article considers a brief review of the foreign publications on the study of the structure, phase composition and properties of five-component high-entropy alloys (HEAs) in different structural states in a wide temperature range over the past two decades. HEAs attract the attention of scientists with their unique and unusual properties. The difficulties of comparative analysis and generalization of data are noted due to different methods of obtaining HEAs, modes of mechanical tests for uniaxial compression and tension, sizes and shapes of the samples, types of thermal treatments, and phase composition (bcc and fcc crystal lattices). It is noted that the HEA with a bcc lattice has mainly high strength and low plasticity, and the HEA with a fcc lattice has low strength and increased plasticity. A significant increase in the properties of the FeMnCoCrNi HEA with a fcc lattice can be achieved by alloying with boron and optimizing the parameters of thermal mechanical treatment at alloying with carbon in the amount of 1 % (at.). The deformation curves analyzed in the temperature range –196 ÷ 800 °C indicate an increase in the yield strength with a decrease in the grain size from 150 to 5 microns. As the temperature decreases, the yield strength and elongation increase. The effect of deformation rate on the mechanical properties is an increase in the ultimate strength and yield strength, which is most noticeable at high rates of 10–2 ÷ 103 s–1. The features of HEAs deformation behavior in the mono- and poly-crystalline states are noted. The complex of high operational properties of HEAs makes it possible to use them in various industries. There are good prospects of using energy treatment to modify the surface layers and further improve HEAs properties.

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.

Experimental investigation of rate dependency of freeze bond strength

The effects of deformation rate on the shear strength of freeze bonds have been investigated through a series of Asymmetric Four-Point Bending (AFPB) experiments. Two submersion times of 30 min and 24 h have been considered, while the deformation rate has been varied from 0.01 to 100 mm/s. Ice specimens with an initial temperature of −18 °C have been subjected to a constant confinement of 25 kPa during formation and shearing of the freeze bonds. Failure of the bonds proved to be highly dependent on deformation rate, where more strain was observed prior to failure of the bond for slower deformation rates. The shear strength of the bond for both submersion times showed a general decreasing trend with increased deformation rate, which is of significant importance in characterizing the properties of ice ridge/rubble strength. Previous ice rubble strength experiments, as well as ice ridge keel gouging tests, have reported the same failure rate-dependency, highlighting the role of freeze bond failure on rate effects. Compressive strength measurements of solid ice presented in the literature have been observed to follow similar trends within the range of strain rates used in present study, where the failure mode appears to transition from ductile to brittle with increasing deformation rate. While more work is needed to understand the mechanisms associated with the rate dependency of freeze bond, this general observation suggests the rate dependency of ice ridges/rubble may indeed be related to the behavior of ice as a material, rather than being associated primarily with factors such as inertial and pore pressure effects, which have been previously proposed as the principal controlling mechanism.

Realization effects of postcritical deformation the regularities for GFRP in tensile tests

Experimental data on mechanical behavior of polymer composite material on the postcritical deformation stage were presented. The typical dependences effect of deformation rate and temperature in a wide range (high and low) on the regularities of deformation and the realization degree of postcritical deformation stage on tensile test were obtained. The tests were carried out on the specimens of constructional glass-reinforced plastic with various lay-up sequences. Test runs were carried out at different loading rates (between 0.1 and 10 mm/min); in a wide temperature range (betwen - 40°C and 200°C) and with different stiffness. The loading conditions are determined under which the degree of implementation of the postcritical stage of deformation increases.

Heterogeneity, suspension, and yielding in sparse microfibrous cellulose gels 2: strain rate-dependent two-fluid behavior

Complex fluids are widely used in formulated products to impart rheological properties like stability, performance, and aesthetics. Yield stress fluids are a particularly important example, enabling applications like particle suspension, surface coating, and therapeutic delivery. Recent work has shown that particle suspension in yield stress fluids can be a strong function of yielding and flow heterogeneities, especially in anisotropic fiber dispersions. This work uses a microbubble technique to study the deformation before and during yielding of microfibrous cellulose suspensions. We note significant variations in suspension performance as a result of fiber rearrangement and heterogeneities. Strong strain rate dependencies are found to vary local network yield strength, and confocal microscopy quantifies structural reinforcement and deformation rate effects. The observed behavior indicates a two-fluid interpretation may help interpret sparse network flow and suspension properties.

Effect of deformation rate on post-forming interfacial delamination in polymer laminated sheet metals

ABSTRACT The polymer laminated sheet metal (PLSM) is a class of layered materials which involves a sheet metal substrate, a polymer film and an adhesive layer between them. The PLSMs can be potentially used for sheet forming applications. Due to the incompatibility in mechanical and physical properties of the constituents, deformation of the PLSM could cause interfacial delamination between the metallic substrate and polymer adherends. This paper deals with the assessment of the effect of uniaxial elongation rate on post-forming interfacial delamination in PLSMs. For the polymer adherends used in this study, it is concluded that for large strains, higher deformation rate results in less amount of delamination. This behavior is attributed to the time-dependency of mechanical properties of the polymer adherend material. Abbreviations: PLSM: polymer laminated sheet metal; PSA: pressure-sensitive adhesive; BA: bright annealed; PE: polyethylene; PP: polypropylene; PVC: polyvinyl chloride

Effects of Deformation Rate on the Unbinding Pathway of the MMP8-Aggrecan_IGD Complex in Cartilage

Mechanical force plays a critical role in the remodeling and degradation of cartilage tissues. The cartilage tissue generates, absorbs, and transmits mechanical force, enabling specific biological processes in our body. A mod... | Find, read and cite all the research you need on Tech Science Press

The effect of the deformation rate on the wall thickness of 1.5LT PET bottle during ISBM (Injection Stretch Blow Molding) process

The biaxial orientation of deformation during the ISBM process forms the final desired volume of the plastic container. The ISBM process comprises stretching and blowing of a preheated preform inside a mold for the formation of a beverage container. The current study deals with the numerical investigation of the effect of deformation rate on the final bottle thickness wall distribution. It was considered that the stretching rod velocity varies from 0.6-0.8m/s and the preblowing pressure from 0.4-1.6MPa. Additionally, the advantage of stretching versus free blow conditions is being discussed. It was found that highest is the stretching velocity, the higher is the resulting material concentration at the base of the bottle. Additionally, it was found that the higher preblowing pressure accumulates thick material at the central region of the bottle while the upper and bottom regions of the bottle get thinner.

Numerical Simulation of the Effect of Deformation Rates on the Dynamic Strength of GFRP Cylindrical Shells

A technique for the numerical analysis of nonlinear dynamic deformation and progressive failure of cylindrical glass-fiber plastic shells is developed with account of their strain-rate-dependent strength characteristics. The kinematic model of deformation of a layer package is based on a nonclassical theory of shells. The geometrical relations are constructed using the simplest quadratic variant of nonlinear elasticity theory. The relationship between the stress and strain tensors in a composite macrolayer is established on the basis of Hooke’s law for an orthotropic body, with account of volatility of the stiffness and strength characteristics of the multilayer package due to a local failure of some elementary layers of the composite and the strain-rate dependence of strength characteristics. An energy-consistent resolving system of dynamics equations for composite cylindrical shells is obtained as a result of minimization of the functional of total energy of the shell as a three-dimensional body. The numerical method for solving the initial boundary-value problem is based on an explicit variationaldifference scheme. The reliability of the technique developed was confirmed by a satisfactory agreement of calculation results with experimental data. For different shell reinforcement structures, qualitative differences in the character and size of failure zones were found, which were calculated by the model considering the strain-rate dependence of strength or their constancy.

Effect of deformation rate on low carbon steels mechanical properties

Study shows the influence of stretching rate on the tensile properties for two low carbon steels during cold plastic deformation. Studies were carried out at laboratory conditions at room temperature with a static tensile test, at stretching rates ranging from 5 to 30 mm / min. Influence of the stretching rate on the elongation (A), tensile strength (Rm), yield stress (Re) and the ratio Re/Rm were analysed by MATLAB software. For both steels, yield stress and tensile strength increase with the increase in stretching rate, while the elongation decreases for both steels. The ratio Re/Rm for niobium microalloyed steel remains constant. It can be concluded that both steels are strain rate sensitive, and that only Re/Rm ratio cannot be used to determine the strain rate sensitivity of the steel.

Unsteady aerodynamics investigation of deploying tandem-wing with different methods

In the rapidly deploying process of the unmanned aerial vehicle with folding wings, the aerodynamic characteristics could be largely different owing to the effects of deformation rate and the aerodynamic interference. The investigation on the unsteady aerodynamics is of great significance for the stability analysis and control design. The lifting-line method and the vortex-lattice method are improved to calculate the unsteady aerodynamics in the morphing stage. It is validated that the vortex-lattice method predicts the unsteady lift coefficient more appropriately than the lifting-line method. Different tandem wing configurations with deployable wings are simulated with different deformation rates during the morphing stage by the vortex-lattice method. As results indicated, the unsteady lift coefficient and the induced drag of the fore wing rise with the deformation rate increasing, but it is reversed for the hind wing. Additionally, the unsteady lift coefficient of the tandem wing configuration performs well with a larger stagger, a larger magnitude of the gap and a larger wingspan of the fore wing; however, the total induced drag has a larger value for the configuration that the two lifting surfaces with the same wingspans are closer to each other.

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.