Artykuły w czasopismach: „Tension-torsion experiments”

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Hou, Pengliang, Huantao Jing, Yujie He, Hongwei Zhao, Haining Xiao i Chunwei Zhang. "Study on the effects of the tension and torsion loading sequence on the mechanical properties of a 20 carbon steel". Materials Testing 64, nr 6 (1.06.2022): 787–99. http://dx.doi.org/10.1515/mt-2021-2202.

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Abstract In engineering applications, cylindrical bars of 20 carbon steel are often subjected to a combination of tensile loading and torsional loading during the service, thereby causing premature failure or an accident. In order to explore the influence of loading sequence of tension and torsion on the mechanical properties of 20 carbon steel, tests of combined tension-torsion loading and combined torsion-tension loading are employed in this work. During experiments, a microscope is used for the in situ characterization of micro-damage evolution on the surface of specimens. At the same time, to analyze the influence of loading sequence on the stress distribution, ABAQUS software is utilized to conduct the relevant finite element simulation, where the results of finite element analysis are consistent with the experiments. Evidently, the torsional strength of 20 carbon steel is decreased with an increase in the pre-tensile stress, under the combined tension-torsion. However, the tensile strength of 20 carbon steel is enhanced with the increasing pre-torsional angles, under the combined torsion-tension. Moreover, the in situ images characterized the micro-damage evolution of 20 carbon steel under pure tension, pure torsion, combined tension-torsion and combined torsion-tension. It is concluded that the deference in loading sequence changes the failure mechanism of 20 carbon steel is different.

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Portier, Laurence, Sylvain Calloch, Didier Marquis i Philippe Geyer. "Ratchetting under tension–torsion loadings: experiments and modelling". International Journal of Plasticity 16, nr 3-4 (styczeń 2000): 303–35. http://dx.doi.org/10.1016/s0749-6419(99)00056-x.

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Han, Yu-Lin, De-Jin Xing, Er-Tian Xiao i Ai-Qun Li. "NiTi-wire Shape Memory Alloy Dampers to Simultaneously Damp Tension, Compression, and Torsion". Journal of Vibration and Control 11, nr 8 (sierpień 2005): 1067–84. http://dx.doi.org/10.1177/1077546305055773.

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NiTi-wire shape memory alloy (SMA) dampers, which utilize NiTi SMA wires to simultaneously damp tension, compression, and torsion, have been developed for structural control implementation in this study. First, three reduced-scale NiTi-wire SMA dampers were constructed. Then, mechanics analysis of the NiTi-wire SMA dampers was performed, based on a model of the SMA-wire restoring force and on tension, compression, and torsion damping analysis. Finally, tension, compression, and torsion experiments were carried out, using the three reduced-scale NiTi-wire SMA dampers of different diameters. The experimental results revealed that all of the three reduced-scale NiTi-wire SMA dampers had the ability to simultaneously supply tension damping, compression damping, and torsion damping, and the results were found to be similar to the damping analytical results.

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Heitzer, M., M. Staat, H. Reiners i F. Schubert. "Shakedown and ratchetting under tension–torsion loadings: analysis and experiments". Nuclear Engineering and Design 225, nr 1 (październik 2003): 11–26. http://dx.doi.org/10.1016/s0029-5493(03)00134-1.

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Mars, W. V., i A. Fatemi. "Observations of the Constitutive Response and Characterization of Filled Natural Rubber Under Monotonic and Cyclic Multiaxial Stress States". Journal of Engineering Materials and Technology 126, nr 1 (1.01.2004): 19–28. http://dx.doi.org/10.1115/1.1631432.

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This work explores the monotonic and cyclic behaviors of filled, natural rubber. Results of stress-strain experiments conducted under stress states of simple, planar, and equibiaxial tension are presented. The ability of hyperelastic models to capture the observed response, as well as recent developments in constitutive modeling of filled rubber such as the consequences of the Mullins effect, are discussed. Monotonic and cyclic multiaxial experiments were also conducted using a short, thin-walled, cylindrical specimen subjected to a wide range of combined axial and twist displacements. Experiments included pure axial tension, pure torsion, combined loading in which the axial and torsion displacements varied proportionally, and combined loading in which the axial and torsion displacements varied non-proportionally (phase between axial and torsion channels of ϕ=0 deg, 90 deg, 180 deg). Results from these tests are presented and discussed, including evolution of stress-strain behavior with load cycles, and the effects of a short period of initial overloading on the subsequent evolution of the stress-strain response.

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Ding, J. L., i W. N. Findley. "Simultaneous and Mixed Stress Relaxation in Tension and Creep in Torsion of 2618 Aluminum". Journal of Applied Mechanics 53, nr 3 (1.09.1986): 529–35. http://dx.doi.org/10.1115/1.3171806.

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The time dependent behavior of 2618-T61 aluminum under mixed loads and constraints (tension relaxation and torsion creep) is investigated. Experiments include tensile relaxation; simultaneous tension relaxation with step changes in torsion creep and reversed torsion; and alternate creep and relaxation. Results were compared with theoretical models developed previously using as input creep and creep recovery data under constant stress states only. Experimental observations were generally well described by strain hardening flow rules. Some failures in describing the material behavior by the state variable approaches (kinematic hardening) are also discussed.

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Ding, Zhi Ping, Ji Ping Chen, Teng Fei Wang i Ming Li. "Influence Analysis of Multifactor on LCF Damage of Single Crystal Nickel-Based Superalloy under Multiaxial Non-Proportional Loading". Advanced Materials Research 139-141 (październik 2010): 198–204. http://dx.doi.org/10.4028/www.scientific.net/amr.139-141.198.

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A formula of equivalent strain for FCC single crystal superalloy was derived based on Hill’s yield criterion and was used for design of biaxial tension-torsion strain paths and loading levels of specimens. biaxial tension-torsion non-proportional cyclic loading process for single crystal nickel-based superalloy at the temperature of 680°C and 850°C was simulated by FEM analyzes; and influence degree of factors, such as strain range, strain path angle, tension-torsion loading phase angle, cycle characteristics and temperature etc., to low cycle fatigue damage of single crystal nickel-based superalloy were analyzed by using analysis of variance based on orthogonal experiments. The results show that if Hill’s equivalent stress range is used as a fatigue damage parameter, the factors produce effects on low cycle fatigue damage of single crystal nickel-based superalloy. The factors are listed in the order of significance as followed: temperature, strain range, tension-torsion loading phase angle, strain path angle and axial loading strain ratio.

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Yang, Li Hong, Guang Ping Zou i Xue Yi Zhang. "Study on Spins and Deformation Rate of Solid Circular Shafts at Finite Torsion Deformation". Key Engineering Materials 452-453 (listopad 2010): 73–76. http://dx.doi.org/10.4028/www.scientific.net/kem.452-453.73.

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Torsion experiments should be adopted to characterize large strain elasto-plastic behavior of material instead of traditional uni-axial tension experiments due to the plastic stability of specimen in torsion deformation. Study on spins and deformation rate in finite torsion deformation is the key to determine the material parameters by torsion experiments and understand the finite deformation characteristics of material. In this paper, five spins and deformation rate in torsion deformation with solid circular shafts are investigated in cylinder coordinates. The expressions of the deformation rate and spins, namely the material spin, the relative spin, the spin of the frame of the deformation rate, logarithmic spin and instantaneous spin considering the effect of stress, are deduced by analyzing the finite torsion deformation. The comparisons are made among all spins obtained in this paper. The results obtained in this paper are the basis of analyzing the large strain constitutive relationship based on torsion experiments with solid circular shafts.

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Concas, Francesca, Stefan Diebels i Anne Jung. "MULTIAXIAL INVESTIGATION OF PVC FOAMS AND ANALYSIS OF THE DEFORMATION MECHANISM BY 3D-DIC". Acta Polytechnica CTU Proceedings 25 (6.12.2019): 6–11. http://dx.doi.org/10.14311/app.2019.25.0006.

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Closed-cell polyvinylchloride (PVC) foams are widely used as core for sandwich composites for applications, in which multiaxial loads are involved. In the present work a wide range of uniaxial (tension, compression and torsion) and multiaxial experiments (both simultaneous tension-torsion and compression-torsion) were conducted on a high performance PVC foam. Failure data for each experiment were collected and depicted in the invariants plane. The whole cylindrical surface of the specimen was monitored by means of an 8-camera-system, strain fields were obtained by 3D-DIC. Hence, the occurrence and the evolution of deformation bands were inspected. The usage of an 8-camera system was essential for the observation of the deformation mechanism, especially for pure compression, pure torsion and combined axial load-torsion, in which the arising of deformation bands is affected by the occurrence of buckling and the orthotropy of the foam.

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Chen, Zi, Qiaohang Guo, Eric Dai, Nickolas Forsch i Larry A. Taber. "How the embryonic chick brain twists". Journal of The Royal Society Interface 13, nr 124 (listopad 2016): 20160395. http://dx.doi.org/10.1098/rsif.2016.0395.

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During early development, the tubular embryonic chick brain undergoes a combination of progressive ventral bending and rightward torsion, one of the earliest organ-level left–right asymmetry events in development. Existing evidence suggests that bending is caused by differential growth, but the mechanism for the predominantly rightward torsion of the embryonic brain tube remains poorly understood. Here, we show through a combination of in vitro experiments, a physical model of the embryonic morphology and mechanics analysis that the vitelline membrane (VM) exerts an external load on the brain that drives torsion. Our theoretical analysis showed that the force is of the order of 10 micronewtons. We also designed an experiment to use fluid surface tension to replace the mechanical role of the VM, and the estimated magnitude of the force owing to surface tension was shown to be consistent with the above theoretical analysis. We further discovered that the asymmetry of the looping heart determines the chirality of the twisted brain via physical mechanisms, demonstrating the mechanical transfer of left–right asymmetry between organs. Our experiments also implied that brain flexure is a necessary condition for torsion. Our work clarifies the mechanical origin of torsion and the development of left–right asymmetry in the early embryonic brain.

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Lin, Hong, Hamid Nayeb-Hashemi, R. M. N. Pelloux i C. A. Berg. "Cyclic Deformation and Anisotropic Constitutive Relations of Al-6061-T6 Under Biaxial Loading". Journal of Engineering Materials and Technology 114, nr 3 (1.07.1992): 323–30. http://dx.doi.org/10.1115/1.2904180.

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Anisotropic cyclic stress-strain curves (CSSCs) were obtained from fully reversed cyclic tests in controlled strain on two orientations of specimens made from an Al-6061-T6 plate (along the rolling direction and perpendicular to the rolling direction). The experiments were conducted at room temperature under three loading conditions: tension/compression, pure torsion and combined tension/torsion in-phase. Based on the CSSCs data, the anisotropic constitutive relations of the material were obtained using Hill’s anisotropic plasticity theory. The coefficients in the yield function were evaluated with a 0.2 percent effective plastic strain criterion. Yield loci and flow behavior were determined for tension/torsion biaxial loading and compared to theoretical predictions. Two anisotropic effective stress-effective strain criteria obtained from the anisotropic constitutive relations were evaluated. A Von Mises type criterion correlated very well with the test data of all specimens under all loadings. The Tresca type criterion did not correlate with the test data.

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Wang, Rui Feng, You Tang Li i Hu Ping An. "Low Cycle Fatigue Life Prediction of Ti-6Al-4V Titanium Alloy under Multi-Axial Non Proportional Cyclic Loading". Advanced Materials Research 668 (marzec 2013): 814–17. http://dx.doi.org/10.4028/www.scientific.net/amr.668.814.

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A series multi-axial tension and torsion low cycle fatigue life experiments of Ti-6Al-4V alloy were conducted on the MTS tension and torsion joint testing machine, in which the torsional strain control and non proportional cyclic loading method under the loading paths of circular, rectangular, square, oval and diamond were successively used. The experimental results are compared and analyzed with the results that calculated by the equivalent strain model, the energy method model and the critical plane method model. The results show that the critical plane method is the accurate prediction model to predict the multi-axial low cycle fatigue life of Ti-6Al-4V alloy.

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Yoshida, Tetsuya, Takayuki Oishi, Michihiro Takiguchi i Fusahito Yoshida. "Viscoplastic Behavior of Acrylic Adhesive in Butt-Joint at Various Temperatures under Complex Loading : Experimentation and Modelling". Key Engineering Materials 340-341 (czerwiec 2007): 1485–90. http://dx.doi.org/10.4028/www.scientific.net/kem.340-341.1485.

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The effects of temperature and strain rate on flow stress of a highly ductile acrylic adhesive were investigated by performing tensile lap shear experiments on an adhesively bonded single-lap joint, as well as torsion experiments on a tubular butt-joint at temperatures ranging from 10 to 40oC at various shear strain rates. The flow stress decreases considerably with decreasing strain rate and with temperature rise. The stress-strain responses under multi-axial stress conditions were also examined by performing combined tension-torsion experiments on the butt-joint. A constitutive model of temperature-dependent elasto-viscoplasticity that describes multi-axial stress-strain behavior of the adhesive is presented.

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Faleskog, Jonas, i Imad Barsoum. "Tension–torsion fracture experiments—Part I: Experiments and a procedure to evaluate the equivalent plastic strain". International Journal of Solids and Structures 50, nr 25-26 (grudzień 2013): 4241–57. http://dx.doi.org/10.1016/j.ijsolstr.2013.08.029.

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Golub, V. P. "Towards the solution of creep problems of thin-shelled tubular elements in isotropic nonlinear viscoelastic materials". Bulletin of Taras Shevchenko National University of Kyiv. Series: Physics and Mathematics, nr 1 (2019): 42–45. http://dx.doi.org/10.17721/1812-5409.2019/1.8.

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A new approach to the creep strains analysis of thin-shelled tubular elements in isotropic nonlinear viscoelastic materials under combined loading with uniaxial tension and torsion has been proposed. The system of equations that is constructed according to the deviators proportionality hypothesis has been chosen as the creep constitutive equations the nonlinearity of viscoelastic properties in which is given with respect to the creep strain intensity and volumetric strain by the Rabotnov type models. The kernels of creep strain intensity and volumetric strain are given by the relations that establish the relationships between these kernels and one-dimensional creep kernels determined from a system of base experiments. One-dimensional tension with the measurement of longitudinal and transverse strains as well as one-dimensional tension and pure torsion with the measurement of longitudinal and shearing strains have been considered as base experiments. The functions of nonlinearity of viscoelastic properties are given by smoothing cubic splines. The problems of the analysis of longitudinal, transverse and shearing strains of thin-shelled tubular specimens made of “high density polyethylene PEHD” have been solved and experimentally approved.

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Sasaki, Yasutoshi, i Mariko Yamasaki. "Effect of pulsating tension-torsion combined loading on fatigue behavior in wood". Holzforschung 58, nr 6 (1.10.2004): 666–72. http://dx.doi.org/10.1515/hf.2004.121.

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Abstract The effect of cyclic tension-torsion combined loading on the fatigue behavior and stress-strain properties of wood (Japanese cypress) was investigated experimentally. The specimen used in the experiments was a rectangular bar with its major axis in the fiber (longitudinal) direction of wood. Pulsating tension and torsion loadings were respectively applied along and around the longitudinal axis of the specimen. According to the relationships between stress and strain obtained using fatigue tests, the secant modulus of the stress-strain curve changed with an increase in the number of loading cycles, and the differences between the curves for tension and shear were observed. The obtained results of fatigue tests were found to be influenced by the combined stress ratios and the applied stress levels. Bordering on the combined stress state of TB, where tensile and shear stress components were almost equally applied, the trend toward lower stiffness retention was different between tension and shear, and the tensile or torsion failure mode became dominant in the failure mode. The TB state was recognized as a boundary state for both of the stiffness retention and the failure mode. The stiffness retention in the TB state showed a tendency similar to that in the stress state where torsion was dominant regardless of the stress level. On the other hand, the failure mode tended to be tension failure at higher stress levels. Thus, at higher stress levels in the TB state, the effect of the tensile or shear stress component on the fatigue behavior of wood was different between “during the fatigue process” and “the time of failure”. In addition, torsion was dominant for both during the fatigue process and the time of failure at lower stress levels.

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Yasmeen, Farzana, Michael A. Sutton, Xiaomin Deng, Megan Ryan i Anthony P. Reynolds. "Parameter Estimation and Application of Anisotropic Yield Criteria for Cylindrical Aluminum Extrusions: Theoretical Developments and StereoDIC Measurements". Applied Sciences 11, nr 20 (18.10.2021): 9701. http://dx.doi.org/10.3390/app11209701.

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Theoretical and experimental studies are presented to characterize the anisotropic plastic response under torsion loading of two nominally identical aluminum Al6061-T6 extruded round bars. Theoretical models are developed using isotropic (Von Mises 1913) and anisotropic (Barlat 1991) yield criteria, along with isotropic strain hardening formulae, to model post-yield behavior under simple torsion loading. For the case of simple shear loading, incremental plasticity theory is used to determine the theoretical elastic, plastic, and total shear strains. A set of experiments are performed to calibrate Barlat’s 1991 yield function. Several specimens are extracted at different orientations to the longitudinal direction of each round Al6061-T6 bar and tested under uniaxial tension and simple torsion to optimally determine all anisotropic (Barlat 1991) yield function parameters. During loading, Stereo Digital Image Correlation (DIC) is used to quantify surface deformations for the torsion experiments and a baseline tension specimen to identify and correct measurement anomalies. Results show the isotropic yield model either underestimates or overestimates the experimental shear strains for both extrusions. Conversely, results using the Barlat 1991 anisotropic yield criteria are in excellent agreement with experimental measurements for both extrusions. The presence of significant differences in the anisotropic parameters for nominally similar extrusions confirms that plastic anisotropy is essential for the accurate prediction of mechanical behavior in longitudinally extruded Al6061-T6 bars.

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Peirs, Jan, Patricia Verleysen, Kim Verbeken, Frederik Coghe i Joris Degrieck. "High Strain Rate Torsion and Bauschinger Tests on Ti6Al4V". Materials Science Forum 706-709 (styczeń 2012): 774–79. http://dx.doi.org/10.4028/www.scientific.net/msf.706-709.774.

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An accurate isotropic and kinematic hardening model and description of the strain rate dependent material behaviour is necessary for simulation of fast forming processes. Consequently, the material model parameter identification requires experiments where large strains, high strain rates and strain path changes can be attained. Usually, quasi-static tension-compression Bauschinger tests are used to assess the materials kinematic hardening. Hereby it’s important to have the same specimen geometry and boundary conditions in the forward and reverse loading step which is not easily achieved in high strain rate testing techniques. In this work, high strain rate split Hopkinson bar torsion experiments on Ti6Al4V are carried out to study the constitutive material behaviour at large plastic strain and strain rate. In torsion experiments, due to the absence of cross sectional area reduction, higher strains than in tensile tests can be obtained. In addition, a modified torsional split Hopkinson bar setup is developed to perform dynamic Bauschinger tests. A shear reversed-shear load is applied instead of the classical tension-compression load cycle. The test results are analysed to find out if the technique can be used for characterisation of the kinematic material behaviour. Digital image correlation and finite element simulations are used to improve the interpretation of the experimental results.

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Wang, Lei, Tian Zhong Sui i Qiu Cheng Tian. "Life Prediction and Verification under Multiaxial Fatigue Loading". Applied Mechanics and Materials 365-366 (sierpień 2013): 991–94. http://dx.doi.org/10.4028/www.scientific.net/amm.365-366.991.

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The strain change characteristics of multiaxial fatigue are analyzed under the condition of the combined tension and torsion loading for thin-tube specimen. Based on the principle of multiaxial critical plane approach, a multiaxial fatigue damage parameter is established, which takes account of the effect of not only the maximum shear strain amplitude and normal strain amplitude on the critical plane but also the parameter of non-proportionality. The non-proportionality is the function of loading parameters which is closely contact with the strain change characteristics of multiaxial fatigue and it can indicate the whole material damage. The experiments under the tension-torsion proportional and non-proportional loading were conducted to verify the multiaxial fatigue life model proposed in this paper. The life prediction has a good correlation with the experimental results.

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Farbaniec, Lukasz, Yuan Xu, Junyi Zhou, Sophoclis Patsias, Duncan Macdougall, Julian Reed, Nik Petrinic, Clive Siviour, Antonio Pellegrino i Daniel E. Eakins. "Application of the Photon Doppler Velocimetry (PDV) technique in tension-torsion Hopkinson bar experiments". EPJ Web of Conferences 250 (2021): 01025. http://dx.doi.org/10.1051/epjconf/202125001025.

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The Photon Doppler Velocimetry (PDV) technique is used to capture simultaneously propagating elastic waves of longitudinal and shear nature in a Tension-Torsion Hopkinson Bar (TTHB) apparatus. The system uses a pair of probes per velocity measurement, which were taken on the opposite sides of the TTHB bar with a laser irradiated spot size of ~35 µm. The collected data were compared to the measurements obtained from the conventional strain gauge technique, and were in good agreement. The PDV method was effective in separating longitudinal and rotation signals even when they were superimposed on each other at the gauge location. This approach is also shown to be effective in detecting and accounting for the presence of bending waves in the TTHB bars.

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Moreno, Belen, A. Garcia-Gonzalez, P. Cobos-Rodriguez, M. Martinez, M. Lopez-Prieto i Pablo Lopez-Crespo. "High Magnification Studies of Fatigue Crack Propagation". Key Engineering Materials 627 (wrzesień 2014): 65–68. http://dx.doi.org/10.4028/www.scientific.net/kem.627.65.

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This work presents a set of experiments devoted to studying the crack initiation stage under different combined tension-compression and torsion loads. Two different load levels were applied, producing very different fatigue lives. Lower strains generated lives approximately 10 times longer than higher strains. Results allowed retardation and acceleration effects due to microstructure to be clearly visualised.

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Wang, C. H., i M. W. Brown. "Life Prediction Techniques for Variable Amplitude Multiaxial Fatigue—Part 2: Comparison With Experimental Results". Journal of Engineering Materials and Technology 118, nr 3 (1.07.1996): 371–74. http://dx.doi.org/10.1115/1.2806822.

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An extensive multiaxial random fatigue test programme was conducted at room temperature using tubular specimens. Experiments were performed under combined tension/torsion and triaxial loading, covering proportional and nonproportional variable amplitude loading cases. The two proposed life prediction methods discussed in Part 1 are evaluated using the experimental results, demonstrating that these two methods provide satisfactory predictions.

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Pavlyuk, Y. V. "Creep of isotropic homogeneous and nonaging of linear-viscoelastic materials under the complex stress state". Bulletin of Taras Shevchenko National University of Kyiv. Series: Physics and Mathematics, nr 1 (2019): 150–53. http://dx.doi.org/10.17721/1812-5409.2019/1.34.

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The relaxation of isotropic homogeneous and non-aging linear-viscoelastic materials under conditions of complex stress state is considered. Thin-walled tubular specimens of High Density Polyethylene (HDPE) for creep under a single-axial stretching, with a pure twist and combined load tension and torsion are considered as base experiments, tests. The solution is obtained by generalizing the initial one-dimensional viscoelasticity model to a complex stressed state, constructed using the hypothesis of the proportionality of deviators. The heredity kernels are given by the Rabotnov’s fractional-exponential function. The dependence between the kernels of intensity and volumetric creep is established, which determine the scalar properties of linear viscoelastic materials in the conditions of a complex stressed state in the defining equations of the type of equations of small elastic-plastic deformations, and the kernels of longitudinal and transverse creep defining the hereditary properties of linear-viscoelastic materials under the conditions of the uniaxial tension. The problems of stress relaxation calculation of thin walled tubes under combined tension with torsion have been solved and experimentally approved.

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Yang, B., Horst Vehoff i Reinhard Pippan. "Overview of the Grain Size Effects on the Mechanical and Deformation Behaviour of Electrodeposited Nanocrystalline Nickel − From Nanoindentation to High Pressure Torsion". Materials Science Forum 633-634 (listopad 2009): 85–98. http://dx.doi.org/10.4028/www.scientific.net/msf.633-634.85.

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A summary of experimental results from nanoindentation, strain rate-controlled tension, in-situ bending and high pressure torsion on bulk electrodeposited nanocrystalline nickel, focusing on the effects of grain size on the mechanical behaviour and deformation mechanisms is presented. The interaction between dislocations and grain boundaries was locally examined by studying the dependence of nanohardness on grain size and indentation size; this is done by always performing nanoindents in the center of individual grains and by varying the grain size and indentation depth systematically. The grain size effects on the different deformation mechanisms of nanocrystalline nickel were revealed by strain rate-controlled tension and nanoindentation experiments, which show that with decreasing grain size the strain rate sensitivity increases and the activation volume decreases, indicating increased grain boundary mediated deformation processes in nanocrystalline nickel. Creep experiments at room temperature revealed that in nanocrystalline nickel grain boundary sliding or diffusion along the interface may dominate at lower stress levels, but with increasing stresses the deformation process is mainly controlled by dislocation creep. In-situ bending experiments in an atomic force microscope revealed directly that grain boundary mediated deformation processes play a significant role in nanocrystalline nickel, which is also supported by the observation of grain coarsening and softening of nanocrystalline nickel caused by high pressure torsion.

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Takeda, Takenobu. "Yield and Flow Behavior of Initially Anisotropic Aluminum Tube Under Multiaxial Stresses". Journal of Engineering Materials and Technology 115, nr 1 (1.01.1993): 77–82. http://dx.doi.org/10.1115/1.2902160.

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By means of combining Drucker’s yield function with Hill’s quadratic yield function, an anisotropic yield function of the sixth degree is proposed. It is able to include the effects of the third deviatoric stress invariant and initial anisotropy. Experiments are carried out on fully annealed 1050 aluminum tubes under multiaxial stress states. By applying proportional loadings of axial load, internal pressure and torsion to the specimens, the change in yield stress with a rotation of the principal stress axes and the difference between the directions of the principal stress and principal strain increment are examined. The yield surface in the tension-internal pressure stress field reveals orthotropic anisotropy. The yield surface in the tension-torsion stress field lies outside von Mises’ yield surface. Such behavioral characteristics can be expressed precisely by the proposed yield function. In addition, it is experimentally verified that the normality rule is obeyed in strain behavior.

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Raut, Devaraj, R. L. Narayan, Yoshihiko Yokoyama, Parag Tandaiya i Upadrasta Ramamurty. "Fracture of notched ductile bulk metallic glass bars subjected to tension-torsion: Experiments and simulations". Acta Materialia 168 (kwiecień 2019): 309–20. http://dx.doi.org/10.1016/j.actamat.2019.02.025.

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Ding, Zhi Ping, Jun Zeng, Xiao Peng Bai i Jian Hui Fang. "Simulation on Stress Relaxation of DD3 Nickel-Based Single Crystal Superalloy Based on Micro-Cell Model". Advanced Materials Research 834-836 (październik 2013): 1557–62. http://dx.doi.org/10.4028/www.scientific.net/amr.834-836.1557.

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Tension-torsion experiments at 680°C and 850°C on thin-wall tube specimens of DD3 nickel-based single crystal superalloys were successfully completed. It shows that specimens have stress relaxation obviously and inelastic deformation accumulation phenomenon with different crystal orientation under asymmetric cyclic loadings. Based on the microstructure characteristics of nickel-based single crystal superalloys, a two-phase multi-cell microscopic mechanical model was established by finite element method to simulate the test with displacement. Numerical simulation studies showed that the matrix phase appeared plastic deformation accumulation at first and resulted in low cycle fatigue damage, but stress distortion occurred on the boundary with a single cell model under tension-torsion displacement loading, which is not consistent with experimental results. While using multi-cell model can avoid this phenomenon, it could be better to simulate stress relaxation behavior under asymmetric cyclic loading at elevated temperature and to study on stress weaken damage for single crystal superalloys.

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Robinson, D. N., i W. K. Binienda. "A Representation of Anisotropic Creep Damage in Fiber Reinforced Composites". Journal of Applied Mechanics 72, nr 4 (28.10.2004): 484–92. http://dx.doi.org/10.1115/1.1875512.

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A creep damage model is presented that allows for anisotropic distributions of damage in composite materials. An earlier model by the writers allowed for anisotropic damage growth rate but, based on a scalar state variable, failed to account for anisotropic distributions of damage. A vectorial state variable is introduced that allows a representation of anisotropic damage distribution. As in earlier work, a fundamental assumption is that the principally damaging stress components are tensile traction and longitudinal shear at the fiber/matrix interface. Application of the creep damage model is made to calculations involving homogenously stressed composite elements under transverse tensile and longitudinal shear stress and to cross plied thin-walled tubes under tension/torsion. Although the emphasis is phenomenological, with focus on a mathematical structure for representing anisotropic distributions of damage, a meaningful creep damage model must rest on fundamental material science and microstructural examination. Verification experiments involving tension/torsion testing of thin-walled composite tubes together with detailed microstructural examination are discussed and outlined.

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29

Nowell, David, i João Vitor Sahadi Cavalheiro. "Approaches to fatigue life prediction under multiaxial loading". MATEC Web of Conferences 300 (2019): 02001. http://dx.doi.org/10.1051/matecconf/201930002001.

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The paper will consider a set of biaxial experiments, conducted using a cruciform specimen design, manufactured from Waspaloy, a nickel superalloy used in aircraft engine disks. These are analysed using a number of standard, as well as novel, multiaxial fatigue parameters. The results show that most of the existing parameters appear to correlate the results adequately in the region which can be accessed by tension-torsion experiments, but are much less convincing outside this range. A number of potential alternative approaches will be discussed and compared with the experimental results.

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Murakami, S., M. Kawai i Y. Yamada. "Creep After Cyclic-Plasticity Under Multiaxial Conditions for Type 316 Stainless Steel at Elevated Temperature". Journal of Engineering Materials and Technology 112, nr 3 (1.07.1990): 346–52. http://dx.doi.org/10.1115/1.2903336.

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History effects of cyclic-plasticity on subsequent creep have been elucidated for type 316 stainless steel at 600°C under multiaxial states of stress. Tension-compression and circular strain paths were specified for the prior cyclic plasticity. Constant stress creep experiments under simple tension, simple torsion, and combined tensiontorsion were first performed after uniaxial tension-compression cycles stabilized under a constant total strain amplitude. Then, in order to elucidate the path shape effects of prior strain cycles, the subsequent creep curves under uniaxial tension were compared for the uniaxial tension-compression and the non-proportional circular strain cycles which stabilized at identical stress amplitudes. The experimental results showed that the prior tension-compression cycles induced the anisotropy in creep behavior; creep resistance which was initially isotropic was enhanced in torsional direction, while it was decreased in tensile one. Another significant observation was that the circular strain cycles showed much larger hardening effect on creep than the tension-compression cycle. Regarding the creep flow direction, the effect of the prior cycles was negligible.

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31

Kořínek, Michal, Radim Halama, František Fojtík, Marek Pagáč, Jiří Krček, David Krzikalla, Radim Kocich i Lenka Kunčická. "Monotonic Tension-Torsion Experiments and FE Modeling on Notched Specimens Produced by SLM Technology from SS316L". Materials 14, nr 1 (23.12.2020): 33. http://dx.doi.org/10.3390/ma14010033.

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The aim of this work was to monitor the mechanical behavior of 316L stainless steel produced by 3D printing in the vertical direction. The material was tested in the “as printed” state. Digital Image Correlation measurements were used for 4 types of notched specimens. The behavior of these specimens under monotonic loading was investigated in two loading paths: tension and torsion. Based on the experimental data, two yield criteria were used in the finite element analyses. Von Mises criterion and Hill criterion were applied, together with the nonlinear isotropic hardening rule of Voce. Subsequently, the load-deformation responses of simulations and experiments were compared. Results of the Hill criterion show better correlation with experimental data. The numerical study shows that taking into account the difference in yield stress in the horizontal direction of printing plays a crucial role for modeling of notched geometries loaded in the vertical direction of printing. Ductility of 3D printed specimens in the “as printed” state is also compared with 3D printed machined specimens and specimens produced by conventional methods. “As printed” specimens have 2/3 lower ductility than specimens produced by a conventional production method. Machining of “as printed” specimens does not affect the yield stress, but a significant reduction of ductility was observed due to microcracks arising from the pores as a microscopic surface study showed.

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32

Lectez, A. S., E. Verron i B. Huneau. "How to identify a hyperelastic constitutive equation for rubber-like materials with multiaxial tension–torsion experiments". International Journal of Non-Linear Mechanics 65 (październik 2014): 260–70. http://dx.doi.org/10.1016/j.ijnonlinmec.2014.06.007.

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Mars, W. V. "Evaluation of a Pseudo-Elastic Model for the Mullins Effect". Tire Science and Technology 32, nr 3 (1.07.2004): 120–45. http://dx.doi.org/10.2346/1.2186778.

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Abstract Typically, the stress-strain response in filled rubbers depends strongly on the maximum loading previously encountered. The phenomenon, known as the Mullins effect, can be idealized for many purposes as an instantaneous and irreversible softening of the stress-strain curve that occurs whenever the load increases beyond its prior all-time maximum value. At times when the load is less than a prior maximum, nonlinear elastic behavior prevails. Ogden and Roxburgh proposed an empirical model capable of describing this phenomenon, based on a pseudo-elastic concept. Their model, with minor adaptations, has recently been implemented in a commercial finite element program. This paper demonstrates the effectiveness of the implemented model for several benchmark cases including uniform hydrostatic loading, simple tension, pure shear, and equibiaxial tension. The paper also compares model predictions with experimental results for a series of experiments conducted with various combinations of axial tension/compression and torsion loading.

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34

Papasidero, J., V. Doquet i D. Mohr. "Determination of the Effect of Stress State on the Onset of Ductile Fracture Through Tension-Torsion Experiments". Experimental Mechanics 54, nr 2 (7.09.2013): 137–51. http://dx.doi.org/10.1007/s11340-013-9788-4.

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Janoušek, Jaromír, Miroslav Balda i Michal Chocholoušek. "Influence of Combined Mean Stresses on Lifetime under High-Cycle Fatigue". Applied Mechanics and Materials 732 (luty 2015): 107–10. http://dx.doi.org/10.4028/www.scientific.net/amm.732.107.

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This study builds on experiments with different combinations of tension and torsion pre-stresses which were published in [1]. The results were particularized by new tests for combined pre-stresses in normal and shear components. The ratio between normal and shear pre-stresses was 3:2 in agreement with the coefficient kc. The same material structural low carbon ČSN 41 1523.1 steel after normalization annealing was used for specimens. The results were compiled and displayed in a three-dimensional Haigh diagram with normalized coordinates and interlaid by corresponding terminal lines.

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36

Major, Štěpán, Štěpán Hubálovský, Vladimír Kocour i Jaroslav Valach. "Effectiveness of the Modified Fatigue Criteria for Biaxial Loading of Notched Specimen in High-Cycle Region". Applied Mechanics and Materials 732 (luty 2015): 63–70. http://dx.doi.org/10.4028/www.scientific.net/amm.732.63.

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This article deals with multiaxial fatigue strength of notched round bars made of Cr-Al-Mo steel and tested under combined tension and torsion loading. Fatigue life is one of the important factors in design since majority of engineering components are subjected to variable loading. Most of mechanical components in engineering practice are subjected to combined loading, which can lead to sudden fatigue failure. In present work the fatigue life of specimens made of low-alloy Cr-Al-Mo high-strength steel is studied. Experiments were focused on the high-cycle fatigue region (over 100 000 cycles to final failure). The most relevant goal of this paper is to verify the efficiency of modified classical multiaxial fatigue criteria. The criterion proposed by Goncalves, Araujo and Mamiya was found to be the best in the fatigue life prediction for bending-torsion loading of notched specimens.

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37

Iyer, Saiganesh K., i Cliff J. Lissenden. "Inelastic Anisotropy of Inconel 718: Experiments and Mathematical Representation". Journal of Engineering Materials and Technology 122, nr 3 (15.03.2000): 321–26. http://dx.doi.org/10.1115/1.482804.

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A generalized threshold function for viscoplastic materials, which can also serve as a yield function in rate-independent plasticity, is suggested for materials that exhibit a strength differential and/or a permanent volume change. The motivation for this type of a threshold function is that experiments, at both 25 and 650°C, on the nickel-based alloy Inconel 718 indicate that higher stresses occur in compression than in tension. Similar results have been obtained for martensitic steels and other metallic alloys at 25°C. A general approach for determining the inelastic flow dependence on each of the three stress invariants (I1,J2, and J3) is to follow stress paths where only one invariant is changing. Two classical experiments that do this are hydrostatic pressure and pure torsion, however many others are possible. Unfortunately, these stress paths generally require three-dimensional stress states, which are difficult to obtain in the laboratory. Thus, for experimental expediency, tests involving axial-torsional loading of thin-walled tubes can be used to determine the significance of the first and third stress invariants, I1 and J3, respectively. [S0094-4289(00)01303-7]

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38

Cao, Shaoyong, Yan Zhu i Yunpeng Jiang. "Notched Behaviors of Carbon Fiber-Reinforced Epoxy Matrix Composite Laminates: Predictions and Experiments". Journal of Composites Science 7, nr 6 (31.05.2023): 223. http://dx.doi.org/10.3390/jcs7060223.

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This paper experimentally studied the influence of the notch shape and size on the damage evolution and failure strength (tension and torsion) of carbon fiber-reinforced epoxy matrix (CFRP) laminates. Hashin’s damage criteria were utilized to monitor the evolution of multi-damage modes, and FEM simulations were also performed by using the ABAQUS code to clarify the specific damage modes in detail as an instructive complement. The failure characteristics of all the notched samples were analyzed and compared with those without notches. The measured results presented that the existence of a variety of notches significantly impaired the load carrying capacity of CFRP laminates. The tensile strengths of C-notch and U-notch increase with an increasing notch radius, while the ultimate torques of C-notch and V-notch decrease with an increasing notch size and angle. The variation in notched properties was explained by different notch shapes and sizes, and the failure characteristics were also presented and compared among notched CFRP laminates with varied notches.

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39

Lesiuk, Grzegorz, Michał Smolnicki, Dariusz Rozumek, Halyna Krechkovska, Oleksandra Student, José Correia, Rafał Mech i Abílio De Jesus. "Study of the Fatigue Crack Growth in Long-Term Operated Mild Steel under Mixed-Mode (I + II, I + III) Loading Conditions". Materials 13, nr 1 (1.01.2020): 160. http://dx.doi.org/10.3390/ma13010160.

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The paper presents an analysis of mixed-mode fatigue crack growth in bridge steel after 100-years operating time. Experiments were carried out under mode I + II configuration on Compact Tension Shear (CTS) specimens and mode I + III on rectangular specimens with lateral stress concentrator under bending and torsion loading type. Due to the lack of accurate Stress Intensity Factor (SIF) solutions, the crack path was modelled with the finite element method according to its experimental observation. As a result, the Kinetic Fatigue Fracture Diagrams (KFFD) were constructed. Due to the change in the tendency of higher fatigue crack growth rates from KI towards KIII dominance for the samples subjected to bending and torsion, it was decided to analyze this phenomenon in detail using electron-scanning microscopy. The fractographic analysis was carried out for specimens subjected to I + III crack loading mode. The mechanism of crack growth in old bridge steel at complex loads was determined and analyzed.

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40

Dörlich, Vanessa, Joachim Linn, Tobias Scheffer i Stefan Diebels. "Towards Viscoplastic Constitutive Models for Cosserat Rods". Archive of Mechanical Engineering 63, nr 2 (1.06.2016): 215–30. http://dx.doi.org/10.1515/meceng-2016-0012.

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Abstract Flexible, slender structures like cables, hoses or wires can be described by the geometrically exact Cosserat rod theory. Due to their complex multilayer structure, consisting of various materials, viscoplastic behavior has to be expected for cables under load. Classical experiments like uniaxial tension, torsion or three-point bending already show that the behavior of e.g. electric cables is viscoplastic. A suitable constitutive law for the observed load case is crucial for a realistic simulation of the deformation of a component. Consequently, this contribution aims at a viscoplastic constitutive law formulated in the terms of sectional quantities of Cosserat rods. Since the loading of cables in applications is in most cases not represented by these mostly uniaxial classical experiments, but rather multiaxial, new experiments for cables have to be designed. They have to illustrate viscoplastic effects, enable access to (viscoplastic) material parameters and account for coupling effects between different deformation modes. This work focuses on the design of such experiments.

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41

Kumar, R. Suresh, C. Lakshmana Rao i P. Chellapandi. "Biaxial Ratcheting Response of SS 316 Steel". Applied Mechanics and Materials 24-25 (czerwiec 2010): 207–11. http://dx.doi.org/10.4028/www.scientific.net/amm.24-25.207.

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Ratcheting is one of the challenging phenomena that needs to be investigated for the Fast breeder reactor (FBRs), to arrive at the optimum structural dimensions that are safe and yet do not have undue redundancy. Austenitic stainless steel is the principal structural material for Indian FBR. Preliminary assessment indicates that there is a need to demonstrate that the main load carrying vessel made of this material can provide sufficient safety margin against ratcheting under biaxial loading conditions. This exercise calls for carrying out many simulated experiments, particularly with biaxial tension torsion specimens to generate adequate data for developing robust constitutive models to predict ratcheting. Accordingly, many biaxial tension-torsion experiments for austenitic stainless steel pipes were conducted and the best results have been reported here. The mechanical behavior of this material has been reported for a given axial tensile stress superimposed with a given range of cyclic shear stress for many cycles of loading. Rectangular rosette is used for capturing the biaxial response. Important material responses like cyclic hardening and biaxial ratcheting have been experimentally observed. Maximum accumulation of 2700 μ axial strain has been observed for a loading condition of constant axial stress of 102 MPa super imposed with a cyclic variation of shear stress amplitude of 120 MPa over 2450 cycles. The amount of progressive accumulation of axial strain was found to be directly dependent on the number of cycles. The observed rate of axial strain accumulation found decreased with increase in number of cycles. All these results are presented in detail in this paper and important conclusions that are useful in modeling the observed behavior are discussed.

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42

Lu, Damin, Keshi Zhang i Guijuan Hu. "Investigation on Plastic Flow Behaviors of FCC Polycrystalline Aluminum under Pre-Cyclic Tension-Compression Loading: Experiments and Crystal Plasticity Modeling". Nanomaterials 11, nr 9 (14.09.2021): 2397. http://dx.doi.org/10.3390/nano11092397.

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The plastic flow behaviors of FCC polycrystalline aluminum after pre-cyclic tension-compression deformation are mainly investigated in tension–torsion stress space by the physically based crystal plasticity model introducing a back-stress. A global finite element model (GFEM) constructed of sufficient grains was established to simulate the same-size thin-walled tube specimen constrained and loaded as the experiments of yield surfaces. The computational results showed that the shape of subsequent yield surfaces and the plastic flow directions directly depended on the given offset strain levels and the applied re-loading paths under different pre-cyclic deformations. The angle deviation between the plastic flow direction and the theoretical orthogonal direction further indicated that there was a large difference between them in the inverse pre-straining direction, but the difference was negligible in the pre-straining direction. From the influence of the anisotropic evolution of the subsequent yield surfaces on plastic flow, we found that the plastic normality rule followed the smooth yield locus; conversely, the significant non-associated flow was attributed to the distorted yield locus. Furthermore, it was also demonstrated that the anisotropic evolution and the plastic flow trend of the subsequent yield surfaces obtained by experiments can be better reproduced by the crystal plasticity model.

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43

Wu, Han-Chin, i Chin-Cheng Ho. "Strain Hardening of Annealed 304 Stainless Steel by Creep". Journal of Engineering Materials and Technology 115, nr 4 (1.10.1993): 345–50. http://dx.doi.org/10.1115/1.2904228.

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Combined axial-torsional experiments have been conducted at room temperature on thin-walled tubes to investigate the strain hardening behavior of annealed 304 stainless steel due to creep. The constant strain-rate dynamic loading (or SCISR) surfaces representing the state of material before and after creep have benn determined. It has been found that transient creep essentially causes the loading surface to undergo kinematic hardening with insignificant amount of isotropic hardening for this material. A conclusion is drawn that the loading surface hardened by transient creep is the same as that hardened by plastic deformation. This is true both for specimens with pure tension and pure torsion loading paths. The results confirm assumptions of the overstress theory of viscoplasticity.

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44

Mars, W. V. "Cracking Energy Density as a Predictor of Fatigue Life under Multiaxial Conditions". Rubber Chemistry and Technology 75, nr 1 (1.03.2002): 1–17. http://dx.doi.org/10.5254/1.3547670.

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Abstract Rubber parts in service often experience complex strain histories that can cause mechanical failure. The ability to predict the effects of complex strain histories on fatigue life is therefore a critical need. This paper presents recent results of cyclic, combined tension/torsion fatigue experiments, and compares them with predictions based on a new parameter, the Cracking Energy Density. The Cracking Energy Density is the stored elastic energy density that is available to a crack on a given material plane, and can be calculated for an arbitrarily complex strain history. The ability of Cracking Energy Density to predict the fatigue life and cracking plane is evaluated for both in-phase and out-of-phase histories of combined axial and shear strain.

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45

Koester, Paul, Christopher Benz i Manuela Sander. "Investigation of mixed mode fatigue crack propagation in SEN-specimen under in-phase and out-of-phase conditions due to tension-compression and torsional loading". MATEC Web of Conferences 300 (2019): 11006. http://dx.doi.org/10.1051/matecconf/201930011006.

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Numerous cases of damage by fatigue in structures are related to mechanical stresses due to mixed mode loading conditions. To prevent such cases of failure a precise knowledge of the corresponding theoretical background is indispensable. Unfortunately, it is not yet possible to describe the crack propagation considering a superposition of all three crack modes satisfactory. For this purpose, experiments on single-edge notched specimens made of 34CrNiMo6 using a tension-torsion testing machine under different mixed mode ratios and phase angles were performed. The focus of the investigations is especially on the kinking and the twisting angle of the crack as well as on the influence on the residual lifetime. Further, existing concepts concerning the prediction of the crack growth under mixed mode are evaluated.

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46

Saif, M. T. A., i N. C. MacDonald. "Microinstruments for submicron material studies". Journal of Materials Research 13, nr 12 (grudzień 1998): 3353–56. http://dx.doi.org/10.1557/jmr.1998.0454.

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We present two microinstruments for submicron scale material characterization. One of the instruments applies torsion on two single crystal silicon bars with square cross sections,1 and 2.25 μm2, until fracture. The maximum shear stress prior to fracture is found tobe 5.6 and 2.6 GPa, respectively. The second instrument applies tension on a composite (aluminum-silicon dioxide) beam, 1 × 1.5 μm2 in cross section. The beam fails at 220 μN.In both the experiments, the samples are designed, patterned, and cofabricated with the instruments. The microinstruments' small size, low thermal mass, vacuum compatibility, and built-in vibration isolation allow material characterization to be performed over a wide range of environmental conditions: high vacuum (electron microscopy and surface analysis), high humidity, high pressure, and high and low temperatures.

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47

Sivak, Roman, i Volodymyr Rekechynsky. "FEATURES OF PLASTIC DEFORMATION OF METALS IN NON-MONITORING DEFORMATION". Vibrations in engineering and technology, nr 2(93) (31.05.2019): 50–55. http://dx.doi.org/10.37128/2306-8744-2019-2-8.

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In this paper we consider two-legged trajectories in the space of the deformation vector. Trajectories were obtained in tensile experiments with subsequent torsion and tensile experiments with subsequent joint tension and stretching of standard solid cylindrical samples from steel 10. Deformation was carried out according to programs that ensure the linearity of trajectories in the deformation space. The components of the stress deviator were determined using an anisotropically strengthened body model. In this experiment, a function characterizing the Bauschinger effect and a function characterizing the hereditary influence of the load history on the current state of the metal during plastic deformation was experimentally determined. It is shown that in the case of nonmonotonic loading, which is characterized by trajectories of large curvature, it is necessary to use O. A. Ilyushin's theory of plasticity, and the model G. Bachhaus yields satisfactory results only for trajectories of medium and low curvature. In general, the suitability of a particular plasticity theory needs to be verified experimentally.

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48

Xue, Zhenyu, Jonas Faleskog i John W. Hutchinson. "Tension–torsion fracture experiments – Part II: Simulations with the extended Gurson model and a ductile fracture criterion based on plastic strain". International Journal of Solids and Structures 50, nr 25-26 (grudzień 2013): 4258–69. http://dx.doi.org/10.1016/j.ijsolstr.2013.08.028.

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Kaneko, Kenji, Akira Ohmori i T. Hiraishi. "Fracture Strength of WC-12Co Thermal Sprayed Coating under Mixed Loading Mode I&III in Crack Surface Displacement". Key Engineering Materials 261-263 (kwiecień 2004): 429–34. http://dx.doi.org/10.4028/www.scientific.net/kem.261-263.429.

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Fracture strength of WC-12Co thermal sprayed coating is investigated experimentally and analytically. In the experiments, one pair of butt cylindrical specimen with coating is subjected to combined tension with torsion stresses. Fracture loci were obtained for three kinds of thickness of the coating in σ-τstress plane. Stress distributions at crack tip singular point on fractured surfaces are analyzed by Finite-Element-Method and approximated by the expression σ＝KR-λ where R means normalized thickness coordinate. It is found that the normal stress distributions are common to all cases of testing stress conditions and so fracture condition of the brittle coating is represented as K≧Kcr in the normal stress distribution even under mixed deformation mode I and III. A critical shear stress distribution for separation could also be obtained

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Kallmeyer, Alan R., Ahmo Krgo i Peter Kurath. "Evaluation of Multiaxial Fatigue Life Prediction Methodologies for Ti-6Al-4V". Journal of Engineering Materials and Technology 124, nr 2 (26.03.2002): 229–37. http://dx.doi.org/10.1115/1.1446075.

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Many critical engineering components are routinely subjected to cyclic multiaxial stress states, which may include non-proportional loading and multidimensional mean stresses. Existing multiaxial fatigue models are examined to determine their suitability at estimating fatigue damage in Ti-6Al-4V under complex, multiaxial loading, with an emphasis on long-life conditions. Both proportional and non-proportional strain-controlled tension/torsion experiments were conducted on solid specimens. Several multiaxial fatigue damage parameters are evaluated based on their ability to correlate the biaxial fatigue data and uniaxial fatigue data with tensile mean stresses (R>−1) to a fully-reversed (R=−1) uniaxial baseline. Both equivalent stress-based models and critical plane approaches are evaluated. Only one equivalent stress model and two critical plane models showed promise for the range of loadings and material considered.

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