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The paper summarizes the findings of theoretical and experimental investigations in the range of low-cycle fatigue under irregular multiaxial deformation. It presents the test results for titanium alloys VT9 and VT1-0 under low-cycle regular and block deformation conditions. A method of fatigue life prediction for metal alloys under multiaxial low-cycle block deformation conditions has been elaborated, which is based on the Pisarenko-Lebedev equivalent deformation and the modified Manson-Halford model. The paper demonstrates the advantages of the proposed method over other approaches to the fatigue life prediction for metal alloys under multiaxial block deformation conditions. [ABSTRACT FROM AUTHOR]

The present paper reports a theoretical study of longitudinal fracture in multilayered beams with taking into account the material nonlinearity. The study was performed in terms of the strain energy release rate by using the classical beam theory. The analysis developed holds for cracked beams whose layers may have different thickness. Moreover, the mechanical behavior of each layer may be described by different nonlinear stress-strain relations. Also, the crack may be located arbitrary along the beam height. The strain energy release rate was expressed in a function of the bending moments and axial loads in the cross sections ahead and behind the crack front. In this way, nonlinear fracture analyses of multilayered beams can be carried out in a closed analytical form. It was shown that the analysis developed is a useful tool for the understanding of nonlinear longitudinal fracture in multilayered beam configurations. [ABSTRACT FROM AUTHOR]

Conical shells are extensively used in numerous types of engineering structures with various types of geometric imperfections. Nonetheless, quite few are the studies investigating the effect of special types of imperfections on the buckling load of conical shells under external pressure. In the present study, depression type of imperfection which is found in the zone of longitudinal weld is in the center of attention. To this end, this paper reports on different simulations including finite element results and discusses the effect of this type of imperfection on the critical buckling load of such structures. Obtained results are compared with the previous corresponding test results, some theoretical predictions, recommendations and codes. [ABSTRACT FROM AUTHOR]

This paper presents the experimental justification of the applicability of a rapid method for the life assessment of heat-resistant steels under cyclic loading in a multiaxial stress state with consideration of metal damage. [ABSTRACT FROM AUTHOR]

The paper presents results of an analysis of the gas-dynamic control of flow around the guide blades of axial compressor stage for the vibration intensity of rotor blades. It has been shown that gas-dynamic action on flow around blades equalizes the flow velocity field before the rotor and reduces the level of resonant stresses in blades in the case of their resonant excitation. [ABSTRACT FROM AUTHOR]

The paper addresses the mechanical behavior of carbon steel 20 in asymmetric loading under the conditions of plane stress state that occurs in a thin-walled specimen in tension-compression and alternating torsion. The asymmetric cyclic loading of specimens was carried out in a stress-controlled mode along three paths with a frequency of 0.1 Hz with a base up to 1200 cycles. Cyclic stress-strain diagrams have been constructed for the specimens under tension-compression, alternating torsion, and proportional loading. The curves of von Mises equivalent ratcheting strains have been plotted. The highest ratcheting rate is shown to take place in the tension-compression loading case. [ABSTRACT FROM AUTHOR]

The paper provides some results of the investigation of the influence of stress state type on accumulation of dispersed damages in structural carbon steel sheet under repeated static biaxial tensile loading. It is shown that the lowest damage accumulation ability of the metal is observed under biaxial tension with a biaxiality index ranging between 0.25 and 0.3. [ABSTRACT FROM AUTHOR]

The paper outlines the methodological approach and the related software package, which permit determining stress-strain state and defect rate for full-scale crack-containing objects. The method is based on computational assessment of the above-mentioned parameters on the condition of minimum of the objective function that describes discrepancy between the experimental data arrays and the results of numerical solutions to model problems using the finite-element method. [ABSTRACT FROM AUTHOR]

The paper addresses the well-known (from available publications) phenomenological strength criteria for anisotropic materials, which are most widely used in application software. [ABSTRACT FROM AUTHOR]

This study aims to establish a practical method for simulating the spindle coupled multi-axial loading fatigue test of a rear axle. A dynamic finite element model of the minivan rear axle was constructed and validated using a static calibration test. Based on the theory and methodology of the Schenck ITFC system, a simulation process was devised which includes system identification, calculation of the input loading signals for the finite element model, calculation of the response stress signals based on this model, calculation of the response strain signals from the corresponding stress signals, and finally, a comparison of the desired and achieved signals. The corresponding data processing programs were made using MATLAB, ensuring their easy reproducibility. The desired signals were measured on the Hainan proving ground for a duration of 2441.216 s, using strain gauges and rosettes placed in important stress-prone locations of the rear axle. The results indicate that the desired signals can be reproduced quite accurately, ensuring that the strain distribution of the rear axle in the field can be reasonably predicted. [ABSTRACT FROM AUTHOR]

The aim of this finite element stress analysis (FEA) study was to assess the effect of separated files (SF) that were broken at two levels (at apical 4 and 9 mm) on the biomechanics of premolars and to determine if removal techniques affect stresses. Six lower premolar teeth were screened on computerized microtomography (micro-CT), standard access cavities were prepared, working lengths were determined, and root canals were prepared (Protaper files, Protaper Universal, Dentsply, Switzerland). Notches were created on the final shaping-file F3 at points 4 and 9 mm from the file tips, inserted in the canals, and squeezed at the apical to break. The roots were rescreened, and SFs were removed by using a Masseran kit (MK; Micro Mega, France), ultrasonic tips (UT; Satelec, Acteon group, France), and the bypass (BP) technique. Final scans were obtained and converted into three-dimensional FEA models. The following conditions were then simulated: a) root-filled tooth with SF; b) root-filled tooth after removal of the SF by using MK, UT, or BP techniques. The models were loaded axially (from two directions) and vertically (300 N), and von Mises stresses were then analyzed. SFs increased the stresses within the root. Longer SFs cause higher stresses within the root and thus should be removed, while short SFs could be kept considering the other clinical factors. Removal via MK caused the highest stresses within the roots among the techniques used. Axial loading caused higher stresses at the cervical side, while the stresses moved toward the apical side under vertical loading. SFs increase the stresses within the root. Long SFs should be removed while short SFs can be left (considering other clinical factors that may affect the success of the treatment). Removing short SFs located at the apical side negatively affects the biomechanics of the teeth, and this effect is more dramatic with the MK technique. [ABSTRACT FROM AUTHOR]

In this study, a refined finite element model of concrete-filled steel tubular column was established, and its dynamic response under impact axial load was explored. By extracting the axial stress changes of the steel tube and the core concrete at different positions of the member, the stress and strain characteristics of the concrete-filled steel tubular column under impact load were obtained for the respective impact loads. It is found that the steel tube and the core concrete basically met the deformation compatibility conditions in the same sections. The whole stress wave velocity of the concrete-filled steel tubular column was between elastic stress wave velocity values of the steel tube and the core concrete. Under the smaller impact load, the axial deformation of the column was close to elastic, whereas under larger impact loads, it underwent significant plastic deformation. [ABSTRACT FROM AUTHOR]

This study outlines the experimental investigation of the steel tube columns filled with selfcompacting concrete under axial compression. The effect of the stiffening arrangements and the concrete strength on the properties of the concrete-filled steel tube columns having stiffeners of different geometric dimensions has been investigated. The failure modes, ultimate loads, stiffness, ductility and strain response of the concrete-filled steel tube columns during the experiment have been analyzed. The results imply that the local buckling of the steel tubes can be delayed by the stiffeners. Moreover, the specimen with the four-sided stiffening arrangement possesses higher stiffness and better ductility as compared with the two-sided one. The test results also demonstrate that the proposed stiffening schemes can improve the ultimate compressive capacity. The predicted ultimate loads have been compared using the existing codes, and the modified formula has been proposed. A good agreement between the theoretical and the experimental results is observed. [ABSTRACT FROM AUTHOR]

The mechanical characteristics of granular matter tested under biaxial loading are studied by numerical simulation. The stress-strain process, volume strain, coordination number, and shear zone are analyzed. The results indicate that the shear zone develops along with the coordination number and volume strain. With an increase in strain, the shear zone is centralized gradually. Moreover, the force transfer in the granular matter is also discussed. [ABSTRACT FROM AUTHOR]

Based on large-scale experimental tests performed on cruciform specimens made of French type RPV steel, the warm prestressing (WPS) effect for LCF (load-cool-fracture) and LCTF (load-cool-transient-fracture) load cycles is studied by finite element simulation. The modified Beremin model is used to determine the fracture probability of the specimens. [ABSTRACT FROM AUTHOR]

The authors present the calculation results for the stress-strain state of the weldment of the 'hot'collector to the nozzle in the PGV-1000 steam generator in the area of welded joint No. 111 in the simulation of the seismic loading specified using the response spectra for the vertical and horizontal vibrations. The calculation of seismic stresses is performed based on the linear-spectral analysis using the three-dimensional model of the WWER-1000/338 reactor plant. [ABSTRACT FROM AUTHOR]

Results are presented for both the calculated assessment of the residual manufacturing stress fields in the simulation of the heat treatment in the vicinity of welded joint No. 111, and the calculation analysis of operating stresses and the fracture resistance of the collector-to-nozzle welded joint in the PGV-1000M steam generator in the simulation of the operating loading cycle. [ABSTRACT FROM AUTHOR]

The effects of temperature, holding time and profile, as well as of biaxiality ratio on crack propagation rate in 12Cr-2Ni-Mo steel have been studied under cyclic loading conditions. It is shown that all the results obtained fall into the tolerance interval with 90% confidence probability. [ABSTRACT FROM AUTHOR]

The effects of the length, sector angle, and different boundary conditions on the buckling load and post buckling behavior of cylindrical panels have been investigated using experimental and numerical methods. The experimental tests have been performed using a servo-hydraulic machine, Instron 8808, and for numerical analysis, Abaqus finite element package has been used. The numerical results are in good agreement with the experimental tests. [ABSTRACT FROM AUTHOR]

We present results of a numerical simulation of the effect of cyclic creep (ratcheting) with different programs of stress-controlled uniaxial asymmetrical loading of two metallic materials with different cyclic properties. An improvement of the kinematic hardening rule in the cyclic plasticity model on the basis of defining equations of the endochronic theory of plasticity is proposed. It has been shown that the proposed model allows one to describe with satisfactory accuracy the kinetics of the stress-strain state of specimens under low-cycle asymmetrical loading on the basis of the minimum number of basic experiments. [ABSTRACT FROM AUTHOR]

method for calculating the fields of parameters of the stress-strain state at the crack tip for mixed modes of loading is developed and implemented taking into account the higher-order terms. The influence of the final crack tip curvature radius on the parameters characterizing the mixed failure modes under plane strain is shown. The nature of influence of the mixed modes of loading and the crack geometry on the behavior of dimensionless angular characteristics of the second term in the expansion of the stresses in the plastic crack tip region is established from the calculation results. The relationships between the mixing, constraint and triaxiality parameters are derived in a full range of mixed deformation modes. [ABSTRACT FROM AUTHOR]

Within the theory of infinitesimal strains, a new approach is proposed for the theoretical construction of the initial and subsequent loading surfaces for simple in Noll's sense initially solid strain-hardening materials of the differential type of complexity 1. The loading surfaces are constructed without making additional assumptions. For the whole class of materials considered, the initial surface has the Huber-Mises form, the subsequent surface undergoes expansion, translation and distortion in the general case. In special cases, the equation of the subsequent loading surface corresponds to the equations of the well-known theories of plasticity with the isotropic-kinematic and kinematic hardening. It is established that the associated flow rule is valid for the initial loading surfaces and regular points of the subsequent loading surfaces. With the accepted definitions of the active loading, unloading and neutral loading, the Drucker postulate is valid for the initial surface and subsequent surfaces of smooth convex shape. The experiments required for the particular definition of the derived dependences are verified. [ABSTRACT FROM AUTHOR]

The creep failure time is calculated for rectilinear thin-walled pipes subjected to combined internal pressure, tension and bending. The failure time calculation is performed using the concept of equivalent stresses. The equivalent stresses are found from the mixed delayed-failure criterion relating the maximum normal stress and the intensity of tangent stresses. The results obtained are compared with literary data for pipes under coupled stresses. The present work can be used to calculate the time to creep failure of thin-walled pipes under internal pressure in combination with axial load and bending. [ABSTRACT FROM AUTHOR]