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Shigeru Kuramoto - One of the best experts on this subject based on the ideXlab platform.
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investigation of strain rate sensitivity of Gum Metal under tension using digital image correlation
Archives of Civil and Mechanical Engineering, 2020Co-Authors: Karol Golasinski, Tadahiko Furuta, E A Pieczyska, M Maj, Maria Staszczak, Pawel świec, Shigeru KuramotoAbstract:Mechanical behavior of a multifunctional titanium alloy Gum Metal was investigated by conducting tensile tests at various strain rates and applying digital image correlation (DIC) technique. Stress–strain curves confirmed low Young’s modulus and high strength of the alloy. The determined values of yield strength had a tendency to increase, whereas the elongation to the specimen rupture tended to decrease with increasing strain rate. True stress versus strain curves were analyzed using selected lengths of virtual extensometer (VE) placed in the strain localization area. When the initial length of the VE was the same as the gauge length, work hardening was observed macroscopically at lower strain rates, and a softening was seen at higher strain rates. However, the softening effect was not observed at the shorter VE lengths. Evolution of the Hencky strain and rate of deformation tensor component fields were analyzed for various strain rates at selected stages of Gum Metal loading. The DIC analysis demonstrated that for lower strain rates the deformation is macroscopically uniform up to the higher average Hencky strains, whereas for higher strain rates the strain localization occurs at the lower average Hencky strains of the deformation process and takes place in the smaller area. It was also found that for all strain rates applied, the maximal values of Hencky strain immediately before rupture of Gum Metal samples were similar for each of the applied strain rates, and the maximal local values of deformation rate were two orders higher when compared to applied average strain rate values.
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development of strain localization in a beta titanium alloy Gum Metal analyzed by infrared camera and digital image correlation for various strain rates
2019Co-Authors: E A Pieczyska, Karol Golasinski, Tadahiko Furuta, M Maj, Shigeru KuramotoAbstract:Effects of thermomechanical couplings were studied in a new beta Ti alloy by IR and DIC techniques. The obtained stress-strain curves confirmed low Young’s modulus and high strength of the alloy. The determined values of yield strength increases and values of elongation till rupture decreases with increasing strain rate. It was found, by using fast and sensitive infrared camera, that the large limit of the Gum Metal reversible nonlinear deformation originates from mechanisms of dissipative nature, probably exothermic stress-induced transition of ” nanodomains.
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a finite strain elastic viscoplastic model of Gum Metal
International Journal of Plasticity, 2019Co-Authors: K Kowalczykgajewska, Shigeru Kuramoto, Karol Golasinski, E A Pieczyska, M Maj, Tadahiko FurutaAbstract:Abstract A hyperelastic-viscoplastic model of Gum Metal is presented. The model is formulated in the large strain framework. The free energy function is postulated consisting of the hyperelastic and viscoplastic components. Original extension of the Neo-Hooke model with a power law component is proposed for hyperelasticity, which enables to describe a relatively large non-linear elastic regime observed for the alloy. Viscoplastic strain follows the Perzyna-type law with an overstress function. The model is implemented into the finite element method and used to simulate the Gum Metal response in multiple tension loading-unloading cycles. The results are compared with experimental outcomes. Good accordance of the simulation results and the available experimental data is obtained.
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yielding and strain localization effects in Gum Metal a unique ti alloy investigated by digital image correlation and infrared thermography
Materials Today: Proceedings, 2019Co-Authors: E A Pieczyska, Tadahiko Furuta, Karol Golasinski, M Maj, Maria Staszczak, Z L Kowalewski, Shigeru KuramotoAbstract:Abstract The research concerns investigation of yielding and developing of the strain localization in new β-Ti alloy characterized by unique elastic-plastic properties, named Gum Metal. The alloy was subjected to tension on testing machine at three various strain rates up to rupture. Digital image correlation and infrared thermography were applied to analyze the experimental results. Strain distributions were determined on the basis of digital image correlation algorithm. The related temperature variations were found in contactless manner using infrared thermography. Mechanical and the corresponding thermal data were used to study the Gum Metal large nonlinear reversible deformation and localization effects
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thermomechanical studies of yielding and strain localization phenomena of Gum Metal under tension
Materials, 2018Co-Authors: E A Pieczyska, Tadahiko Furuta, Karol Golasinski, M Maj, Maria Staszczak, Shigeru KuramotoAbstract:This paper presents results of investigation of multifunctional β-Ti alloy Gum Metal subjected to tension at various strain rates. Digital image correlation was used to determine strain distributions and stress-strain curves, while infrared camera allowed for us to obtain the related temperature characteristics of the specimen during deformation. The mechanical curves completed by the temperature changes were applied to analyze the subsequent stages of the alloy loading. Elastic limit, recoverable strain, and development of the strain localization were studied. It was found that the maximal drop in temperature, which corresponds to the yield limit of solid materials, was referred to a significantly lower strain value in the case of Gum Metal in contrast to its large recoverable strain. The temperature increase proves a dissipative character of the process and is related to presence of ω and α″ phases induced during the alloy fabrication and their exothermic phase transformations activated under loading. During plastic deformation, both the strain and temperature distributions demonstrate that strain localization for higher strain rates starts nucleating just after the yield limit leading to specimen necking and rupture. Macroscopically, it is exhibited as softening of the stress-strain curve in contrast to the strain hardening observed at lower strain rates.
Tadahiko Furuta - One of the best experts on this subject based on the ideXlab platform.
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investigation of strain rate sensitivity of Gum Metal under tension using digital image correlation
Archives of Civil and Mechanical Engineering, 2020Co-Authors: Karol Golasinski, Tadahiko Furuta, E A Pieczyska, M Maj, Maria Staszczak, Pawel świec, Shigeru KuramotoAbstract:Mechanical behavior of a multifunctional titanium alloy Gum Metal was investigated by conducting tensile tests at various strain rates and applying digital image correlation (DIC) technique. Stress–strain curves confirmed low Young’s modulus and high strength of the alloy. The determined values of yield strength had a tendency to increase, whereas the elongation to the specimen rupture tended to decrease with increasing strain rate. True stress versus strain curves were analyzed using selected lengths of virtual extensometer (VE) placed in the strain localization area. When the initial length of the VE was the same as the gauge length, work hardening was observed macroscopically at lower strain rates, and a softening was seen at higher strain rates. However, the softening effect was not observed at the shorter VE lengths. Evolution of the Hencky strain and rate of deformation tensor component fields were analyzed for various strain rates at selected stages of Gum Metal loading. The DIC analysis demonstrated that for lower strain rates the deformation is macroscopically uniform up to the higher average Hencky strains, whereas for higher strain rates the strain localization occurs at the lower average Hencky strains of the deformation process and takes place in the smaller area. It was also found that for all strain rates applied, the maximal values of Hencky strain immediately before rupture of Gum Metal samples were similar for each of the applied strain rates, and the maximal local values of deformation rate were two orders higher when compared to applied average strain rate values.
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development of strain localization in a beta titanium alloy Gum Metal analyzed by infrared camera and digital image correlation for various strain rates
2019Co-Authors: E A Pieczyska, Karol Golasinski, Tadahiko Furuta, M Maj, Shigeru KuramotoAbstract:Effects of thermomechanical couplings were studied in a new beta Ti alloy by IR and DIC techniques. The obtained stress-strain curves confirmed low Young’s modulus and high strength of the alloy. The determined values of yield strength increases and values of elongation till rupture decreases with increasing strain rate. It was found, by using fast and sensitive infrared camera, that the large limit of the Gum Metal reversible nonlinear deformation originates from mechanisms of dissipative nature, probably exothermic stress-induced transition of ” nanodomains.
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a finite strain elastic viscoplastic model of Gum Metal
International Journal of Plasticity, 2019Co-Authors: K Kowalczykgajewska, Shigeru Kuramoto, Karol Golasinski, E A Pieczyska, M Maj, Tadahiko FurutaAbstract:Abstract A hyperelastic-viscoplastic model of Gum Metal is presented. The model is formulated in the large strain framework. The free energy function is postulated consisting of the hyperelastic and viscoplastic components. Original extension of the Neo-Hooke model with a power law component is proposed for hyperelasticity, which enables to describe a relatively large non-linear elastic regime observed for the alloy. Viscoplastic strain follows the Perzyna-type law with an overstress function. The model is implemented into the finite element method and used to simulate the Gum Metal response in multiple tension loading-unloading cycles. The results are compared with experimental outcomes. Good accordance of the simulation results and the available experimental data is obtained.
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yielding and strain localization effects in Gum Metal a unique ti alloy investigated by digital image correlation and infrared thermography
Materials Today: Proceedings, 2019Co-Authors: E A Pieczyska, Tadahiko Furuta, Karol Golasinski, M Maj, Maria Staszczak, Z L Kowalewski, Shigeru KuramotoAbstract:Abstract The research concerns investigation of yielding and developing of the strain localization in new β-Ti alloy characterized by unique elastic-plastic properties, named Gum Metal. The alloy was subjected to tension on testing machine at three various strain rates up to rupture. Digital image correlation and infrared thermography were applied to analyze the experimental results. Strain distributions were determined on the basis of digital image correlation algorithm. The related temperature variations were found in contactless manner using infrared thermography. Mechanical and the corresponding thermal data were used to study the Gum Metal large nonlinear reversible deformation and localization effects
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thermomechanical studies of yielding and strain localization phenomena of Gum Metal under tension
Materials, 2018Co-Authors: E A Pieczyska, Tadahiko Furuta, Karol Golasinski, M Maj, Maria Staszczak, Shigeru KuramotoAbstract:This paper presents results of investigation of multifunctional β-Ti alloy Gum Metal subjected to tension at various strain rates. Digital image correlation was used to determine strain distributions and stress-strain curves, while infrared camera allowed for us to obtain the related temperature characteristics of the specimen during deformation. The mechanical curves completed by the temperature changes were applied to analyze the subsequent stages of the alloy loading. Elastic limit, recoverable strain, and development of the strain localization were studied. It was found that the maximal drop in temperature, which corresponds to the yield limit of solid materials, was referred to a significantly lower strain value in the case of Gum Metal in contrast to its large recoverable strain. The temperature increase proves a dissipative character of the process and is related to presence of ω and α″ phases induced during the alloy fabrication and their exothermic phase transformations activated under loading. During plastic deformation, both the strain and temperature distributions demonstrate that strain localization for higher strain rates starts nucleating just after the yield limit leading to specimen necking and rupture. Macroscopically, it is exhibited as softening of the stress-strain curve in contrast to the strain hardening observed at lower strain rates.
J W Morris - One of the best experts on this subject based on the ideXlab platform.
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multiscale analysis of nanoindentation induced defect structures in Gum Metal
Acta Materialia, 2018Co-Authors: R P Sankaran, Vasfi Burak Ozdol, Colin Ophus, Josh Kacher, Christoph Gammer, Sanjay Govindjee, Andrew M Minor, J W MorrisAbstract:Abstract Using ex-situ transmission electron microscopy and the recently developed nanoprobe diffraction (NPD) technique, we characterize a nanoindented solution treated Gum Metal. Lattice rotations are resolved at a 1.2 nm length-scale and shown to be continuous within the nanoindentation pit; further, it is shown that these can be accommodated by a reasonable number of geometrically necessary dislocations at a density of ∼1015/m2. We additionally provide direct evidence that dislocations within the nanoindent, rather than secondary phase nanoparticles, can serve as potent barriers to dislocation motion. We also demonstrate that plasticity in these alloys under nanoindentation can be accommodated solely by dislocation nucleation and propagation, with no competing deformation mechanisms present. Conventional transmission electron microscopy and “g•b” analysis reveal the presence of dislocations on 〈 1 ¯ 11 〉 {110} slip systems and highly localized plastic deformation in the form of shear bands on { 1 ¯ 1 ¯ 2 } slip systems, similar to previously observed “giant faults”.
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haadf imaging of the omega ω phase in a Gum Metal related alloy
Philosophical Magazine, 2014Co-Authors: R P Sankaran, Colin Ophus, Andrew M Minor, Burak Ozdol, V Radmilovic, J W MorrisAbstract:Nanosized precipitates have been observed in a Nb-lean Gum Metal-related alloy, Ti–20.0Nb–0.6Ta–1.7Zr–1.1O at.% (Ti–31.9Nb–2.0Ta–2.7Zr–0.3O wt.%) using probe-corrected high-resolution scanning transmission electron microscopy with a high-angle annular dark-field detector (HAADF). This characterization yields three distinct atomic motifs and STEM multislice simulations are semi-quantitatively used to verify that each motif can be attributed to the widely observed “athermal” omega phase. However, the presence of chemical ordering cannot be unambiguously ruled out in this system. Data presented here, demonstrate the complexity of interpreting HAADF images of multiphase, multicomponent alloys when complementary experimental data are unavailable.
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the mechanism of strength and deformation in Gum Metal
Scripta Materialia, 2013Co-Authors: Tadahiko Furuta, J W Morris, Shigeru Kuramoto, Naoyuki Nagasako, E Withey, D. C. ChrzanAbstract:Abstract “Gum Metal” refers to β-Ti alloys that achieve exceptional elastic elongation and, with a specific alloy composition, appear to deform via a dislocation-free mechanism involving elastic instability at the limit of strength. This paper describes the current status of research on its strength, deformation mechanism and the possible role of stress-induced martensite. The theoretical basis for deformation at ideal strength is presented. The relevant experimental data is then discussed, including ex situ nanoindentation behavior and in situ pillar compression observed by transmission electron microscopy.
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phonons and phase stability in ti v approximants to Gum Metal
Physical Review B, 2012Co-Authors: Yuranan Hanlumyuang, R P Sankaran, J W Morris, M P Sherburne, D. C. ChrzanAbstract:The stability of competing phases within body-centered-cubic Ti-V approximants to Gum Metal is considered from the perspective of phonon dispersion. Phonons are associated with the potential to form the $\ensuremath{\omega}$ and ${\ensuremath{\alpha}}^{\ensuremath{'}\ensuremath{'}}$ phases. It is argued that alloys can be designed to be linearly stable with respect to the formation of both phases, even as the ideal shear strength approaches zero. The reduction in ideal strength is associated with softening of the phonons along $\ensuremath{\Gamma}\ensuremath{-}N$ and is reflected in diffuse-scattering diffraction experiments.
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anomalous transformation induced deformation in Gum Metal
Key Engineering Materials, 2011Co-Authors: J W Morris, D. C. Chrzan, Shigeru KuramotoAbstract:Tensile tests of single crystals of Gum Metal (Ti-36Nb-2Ta-3Zr-0.3O (wt %)) showed, anomalously, that (1) extensive, stress-induced (bcc)”(orthorhombic) transformation occurred in a crystal pulled in the direction, but no transformation was observed in crystals pulled in the or directions and (2) little or no transformation occurred in tensile tests of severely worked rods, which are polycrystals with very strong texture. Analysis of the energetics of the ” transformation offers straightforward explanations for these results. (1) An ” precipitate has very low elastic energy if it forms as a thin plate with a habit near {11√2}. A tensile load significantly decreases the energy of this plate, promoting the transformation; loading along or is much less effective. (2) While cold-swaged rods of Gum Metal have a strong axial texture, their perpendicular planes are severely distorted, increasing the elastic energy of ” and inhibiting the transformation.
D. C. Chrzan - One of the best experts on this subject based on the ideXlab platform.
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ab initio calculation of thermal expansion with application to understanding invar behavior in Gum Metal
Physical Review Materials, 2018Co-Authors: D. C. Chrzan, I S Winter, Joseph Montoya, K A PerssonAbstract:A theoretical examination of the thermal expansion behavior of a variety of Metals is conducted using a combination of nonlinear elasticity theory and first-principles calculations that is suitable for high throughput computation. Results of this method show good agreement with experimental values. This method is then used to better understand the low thermal expansion behavior of Gum Metal by comparing the thermal expansion tensor of ${\mathrm{Ti}}_{3}\mathrm{Nb}$ austenitic ($\ensuremath{\beta}$) and martensitic (${\ensuremath{\alpha}}^{\ensuremath{''}}$) Gum Metal approximants. The thermal expansion coefficient of $\ensuremath{\beta}$ is found to be in agreement with experimental results for that of annealed Gum Metal. The thermal expansion tensor of the ${\ensuremath{\alpha}}^{\ensuremath{''}}$ phase is shown to be highly anisotropic and exhibit negative thermal expansion along ${\ensuremath{\langle}110\ensuremath{\rangle}}_{\ensuremath{\beta}}$. It is demonstrated that the thermal expansion of the two-phase system, $\ensuremath{\beta}+{\ensuremath{\alpha}}^{\ensuremath{''}}$, can be estimated using the rule of mixing. By applying this averaging scheme and allowing a texturing along $\ensuremath{\langle}110\ensuremath{\rangle}{{001}}_{\ensuremath{\beta}}$ in tandem with the growth of the ${\ensuremath{\alpha}}^{\ensuremath{''}}$ phase, values for the thermal expansion similar to that seen in cold-rolled Gum Metal are calculated.
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computing elastic anisotropy to discover Gum Metal like structural alloys
Physical Review Materials, 2017Co-Authors: D. C. Chrzan, I S Winter, M De Jong, Mark AstaAbstract:The computer aided discovery of structural alloys is a burgeoning but still challenging area of research. A primary challenge in the field is to identify computable screening parameters that embody key structural alloy properties. Here, an elastic anisotropy parameter that captures a material's susceptibility to solute solution strengthening is identified. The parameter has many applications in the discovery and optimization of structural materials. As a first example, the parameter is used to identify alloys that might display the super elasticity, super strength, and high ductility of the class of TiNb alloys known as Gum Metals. In addition, it is noted that the parameter can be used to screen candidate alloys for shape memory response, and potentially aid in the optimization of the mechanical properties of high-entropy alloys.
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lattice softening in body centered cubic lithium magnesium alloys
Physical Review Materials, 2017Co-Authors: D. C. Chrzan, I S Winter, Tomohito TsuruAbstract:A first-principles investigation of the influence of lattice softening on lithium-magnesium alloys near the body-centered-cubic (bcc)/hexagonal close-packed (hcp) transition composition is presented. Results show that lithium-magnesium alloys display a softening of the shear modulus ${C}_{11}\ensuremath{-}{C}_{12}$, and an acoustic phonon branch between the $\mathrm{\ensuremath{\Gamma}}$ and $N$ high symmetry points, as the composition approaches the stability limit for the bcc phase. This softening is accompanied by an increase in the size of the dislocation core region. Ideal tensile strength calculations predict that ordered phases of lithium-magnesium alloys are intrinsically brittle. Methods to make the alloys more ductile are discussed, and the propensity for these alloys to display Gum-Metal-like behavior is assessed.
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the mechanism of strength and deformation in Gum Metal
Scripta Materialia, 2013Co-Authors: Tadahiko Furuta, J W Morris, Shigeru Kuramoto, Naoyuki Nagasako, E Withey, D. C. ChrzanAbstract:Abstract “Gum Metal” refers to β-Ti alloys that achieve exceptional elastic elongation and, with a specific alloy composition, appear to deform via a dislocation-free mechanism involving elastic instability at the limit of strength. This paper describes the current status of research on its strength, deformation mechanism and the possible role of stress-induced martensite. The theoretical basis for deformation at ideal strength is presented. The relevant experimental data is then discussed, including ex situ nanoindentation behavior and in situ pillar compression observed by transmission electron microscopy.
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phonons and phase stability in ti v approximants to Gum Metal
Physical Review B, 2012Co-Authors: Yuranan Hanlumyuang, R P Sankaran, J W Morris, M P Sherburne, D. C. ChrzanAbstract:The stability of competing phases within body-centered-cubic Ti-V approximants to Gum Metal is considered from the perspective of phonon dispersion. Phonons are associated with the potential to form the $\ensuremath{\omega}$ and ${\ensuremath{\alpha}}^{\ensuremath{'}\ensuremath{'}}$ phases. It is argued that alloys can be designed to be linearly stable with respect to the formation of both phases, even as the ideal shear strength approaches zero. The reduction in ideal strength is associated with softening of the phonons along $\ensuremath{\Gamma}\ensuremath{-}N$ and is reflected in diffuse-scattering diffraction experiments.
Karol Golasinski - One of the best experts on this subject based on the ideXlab platform.
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quasi static and dynamic compressive behavior of Gum Metal experiment and constitutive model
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2021Co-Authors: Karol Golasinski, Maciej Zubko, Jacek Janiszewski, Judyta Sienkiewicz, Tomasz Plocinski, Pawel świec, E A PieczyskaAbstract:The quasi-static and high strain rate compressive behavior of Gum Metal with composition Ti-36Nb-2Ta-3Zr-0.3O (wt pct) has been investigated using an electromechanical testing machine and a split Hopkinson pressure bar, respectively. The stress–strain curves obtained for Gum Metal tested under monotonic and dynamic loadings revealed a strain-softening effect which intensified with increasing strain rate. Moreover, the plastic flow stress was observed to increase for both static and dynamic loading conditions with increasing strain rate. The microstructural characterization of the tested Gum Metal specimens showed particular deformation mechanisms regulating the phenomena of strain hardening and strain softening, namely an adiabatic shear band formed at ~ 45 deg with respect to the loading direction as well as widely spaced deformation bands (kink bands). Dislocations within the channels intersecting with twins may cause strain hardening while recrystallized grains and kink bands with crystal rotation inside the grains may lead to strain softening. A constitutive description of the compressive behavior of Gum Metal was proposed using a modified Johnson–Cook model. Good agreement between the experimental and the numerical data obtained in the work was achieved.
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evaluation of mechanical properties in vitro corrosion resistance and biocompatibility of Gum Metal in the context of implant applications
Journal of The Mechanical Behavior of Biomedical Materials, 2021Co-Authors: Karol Golasinski, E A Pieczyska, S Mackiewicz, Maciej Zubko, Rainer Detsch, Magdalena Szklarska, B łosiewicz, Aldo R BoccacciniAbstract:Abstract In recent decades, several novel Ti alloys have been developed in order to produce improved alternatives to the conventional alloys used in the biomedical industry such as commercially pure titanium or dual phase (alpha and beta) Ti alloys. Gum Metal with the non-toxic composition Ti–36Nb–2Ta–3Zr–0.3O (wt. %) is a relatively new alloy which belongs to the group of metastable beta Ti alloys. In this work, Gum Metal has been assessed in terms of its mechanical properties, corrosion resistance and cell culture response. The performance of Gum Metal was contrasted with that of Ti–6Al–4V ELI (extra-low interstitial) which is commonly used as a material for implants. The advantageous mechanical characteristics of Gum Metal, e.g. a relatively low Young's modulus (below 70 GPa), high strength (over 1000 MPa) and a large range of reversible deformation, that are important in the context of potential implant applications, were confirmed. Moreover, the results of short- and long-term electrochemical characterization of Gum Metal showed high corrosion resistance in Ringer's solution with varied pH. The corrosion resistance of Gum Metal was best in a weak acid environment. Potentiodynamic polarization studies revealed that Gum Metal is significantly less susceptible to pitting corrosion compared to Ti–6Al–4V ELI. The oxide layer on the Gum Metal surface was stable up to 8.5 V. Prior to cell culture, the surface conditions of the samples, such as nanohardness, roughness and chemical composition, were analyzed. Evaluation of the in vitro biocompatibility of the alloys was performed by cell attachment and spreading analysis after incubation for 48 h. Increased in vitro MC3T3-E1 osteoblast viability and proliferation on the Gum Metal samples was observed. Gum Metal presented excellent properties making it a suitable candidate for biomedical applications.
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anisotropy of Gum Metal analysed by ultrasonic measurement and digital image correlation
Materials Science and Technology, 2020Co-Authors: Karol Golasinski, E A Pieczyska, M Maj, S Mackiewicz, Maria Staszczak, Z L Kowalewski, Leszek Urbanski, Maciej Zubko, Naohisa TakesueAbstract:The mechanical anisotropy of a multifunctional titanium alloy, Gum Metal, is investigated in this paper. The structural characterisation showed a strong texture for Gum Metal, that is a resul...
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investigation of strain rate sensitivity of Gum Metal under tension using digital image correlation
Archives of Civil and Mechanical Engineering, 2020Co-Authors: Karol Golasinski, Tadahiko Furuta, E A Pieczyska, M Maj, Maria Staszczak, Pawel świec, Shigeru KuramotoAbstract:Mechanical behavior of a multifunctional titanium alloy Gum Metal was investigated by conducting tensile tests at various strain rates and applying digital image correlation (DIC) technique. Stress–strain curves confirmed low Young’s modulus and high strength of the alloy. The determined values of yield strength had a tendency to increase, whereas the elongation to the specimen rupture tended to decrease with increasing strain rate. True stress versus strain curves were analyzed using selected lengths of virtual extensometer (VE) placed in the strain localization area. When the initial length of the VE was the same as the gauge length, work hardening was observed macroscopically at lower strain rates, and a softening was seen at higher strain rates. However, the softening effect was not observed at the shorter VE lengths. Evolution of the Hencky strain and rate of deformation tensor component fields were analyzed for various strain rates at selected stages of Gum Metal loading. The DIC analysis demonstrated that for lower strain rates the deformation is macroscopically uniform up to the higher average Hencky strains, whereas for higher strain rates the strain localization occurs at the lower average Hencky strains of the deformation process and takes place in the smaller area. It was also found that for all strain rates applied, the maximal values of Hencky strain immediately before rupture of Gum Metal samples were similar for each of the applied strain rates, and the maximal local values of deformation rate were two orders higher when compared to applied average strain rate values.
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development of strain localization in a beta titanium alloy Gum Metal analyzed by infrared camera and digital image correlation for various strain rates
2019Co-Authors: E A Pieczyska, Karol Golasinski, Tadahiko Furuta, M Maj, Shigeru KuramotoAbstract:Effects of thermomechanical couplings were studied in a new beta Ti alloy by IR and DIC techniques. The obtained stress-strain curves confirmed low Young’s modulus and high strength of the alloy. The determined values of yield strength increases and values of elongation till rupture decreases with increasing strain rate. It was found, by using fast and sensitive infrared camera, that the large limit of the Gum Metal reversible nonlinear deformation originates from mechanisms of dissipative nature, probably exothermic stress-induced transition of ” nanodomains.