Academic literature on the topic 'Generalized critical plane criterion'
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Journal articles on the topic "Generalized critical plane criterion"
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Crăciun, Eduard Marius, Marin Marin, and Adrian Răbâea. "Anti-plane crack in human bone. I. Mathematical modelling." Analele Universitatii "Ovidius" Constanta - Seria Matematica 26, no. 1 (March 1, 2018): 81–90. http://dx.doi.org/10.2478/auom-2018-0004.
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Abstract We consider an anti-plane crack in a bone, considered as an initially deformed orthotropic, linear elastic composite material. Elastic incremental fields in the composite material are obtained following theories of Guz’s representation and of Riemann-Hilbert problem. Critical values of crack propagation angle are determined using Sih’s generalized criterion.
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Craciun, Eduard Marius, Tomasz Sadowski, Liviu Marsavina, and Adrian Rabaea. "Mathematical Aspects Regarding Cracks Behaviour in Wood Composites." Key Engineering Materials 601 (March 2014): 108–11. http://dx.doi.org/10.4028/www.scientific.net/kem.601.108.
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In this paper we study the interaction of two unequal collinear cracks in a pre-stressed fiber reinforced wood composite material in anti-plane mode of fracture. A mathematical model is associated to the mechanical problem. Starting from the boundary, constitutive and far field conditions we obtain the representation of the incremental displacement, stress and strain fields using two complex potentials. Using Sih s generalized fracture criterion we determine the critical incremental shear stress which produce crack propagation and the crack tips propagation direction in a particular case of a Pine wood composite.
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Loghman, A., and M. A. Wahab. "Loading and Unloading of Thick-Walled Cylindrical Pressure Vessels of Strain-Hardening Material." Journal of Pressure Vessel Technology 116, no. 2 (May 1, 1994): 105–9. http://dx.doi.org/10.1115/1.2929562.
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A thick-walled closed-end cylinder of isotropic, homogeneous and strain-hardening material is considered in this study. Loading is assumed to consist of a temperature gradient as well as an internal pressure. Unloading is completely elastic without considering a Bauschinger effect. A generalized plane strain case in which the material obeys Von Mises yield criterion is studied. Using the yield criterion, critical conditions for a wide range of loading combinations and thickness ratios are investigated. After the critical condition is established, load is increased beyond the critical values and calculations are made for plastic stresses and strains and progress of plastic zone using an incremental theory of plasticity. Residual stresses are obtained as the cylinder is unloaded from a 25 and 50-percent overstrained condition. Reverse yielding is not considered while the residual stresses at the onset of reverse yielding are calculated. Loading function is assumed to follow the stress-strain curve of SUS 304 at a constant temperature of 400°C, which is selected from the experimental work of earlier researchers.
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Kacker, Ruchin, and Shailendra Singh Bhadauria. "Investigations on critical anisotropic triaxiality at the crack tip under mixed-mode (I + II) fracture." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, no. 13 (February 6, 2019): 4688–706. http://dx.doi.org/10.1177/0954406219827337.
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In this analytical study, anisotropic triaxiality, at the yield loci of the crack tip under mixed-mode (I + II) loading, has been modeled. According to the well-known M-criterion the crack of any orientation from the loading axis, initiates at a polar angle at which criticality of triaxiality occurs. Thus, the critical values of triaxiality have been obtained by statistically evaluating the proposed model for various crack inclinations. The combination of six anisotropic constants classifies the five different yield conditions, which are useful in various alloys. Hill’s generalized anisotropic yield equation generates these yield conditions. The assumption of limited plastic deformation at the crack tip has been the basis of analysis. In particular, the principle of linear elastic fracture mechanics (considering small-scale yielding) holds well. Plastic zone shapes at the crack tip for various crack inclinations are plotted to supplement the results obtained from critical values of triaxiality. For both, plane stress and plane strain conditions, the analysis reveals the regions of the degree of anisotropy for particular Lankford’s coefficient and vice versa where the crack initiation angles show variations.
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Liao, Mengke, Yuanming Lai, and Chong Wang. "A strength criterion for frozen sodium sulfate saline soil." Canadian Geotechnical Journal 53, no. 7 (July 2016): 1176–85. http://dx.doi.org/10.1139/cgj-2015-0569.
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Salt content has been proven to be an important influencing factor on the mechanical properties of frozen saline soils, whose strength criterion is different from that of unfrozen saline soils or frozen soils without salts. In this paper, a series of conventional triaxial tests are carried out for frozen saline soils with sodium sulfate at a temperature of –6 °C. A strength criterion of the frozen saline soils, including the influence of salt content, is established by using the generalized nonlinear strength theory. Based on conventional triaxial test results, a modified hydrostatic pressure expression is proposed according to the critical strength function of the modified Cam clay model in the meridian plane. The influence of salt content on the shear strength of the frozen saline soils is investigated according to their freezing temperature curves as well as the formation of salt and ice crystals. The relationship between salt content and friction angle is analyzed. The proposed strength criterion of frozen saline soil is proved to be reliable by extrusion elongation triaxial tests. This criterion can reasonably reflect the major nonlinear strength characteristics of frozen saline soils, including the influences of change in salt content, pressure melting, and ice crushing.
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Chang, Ming-Fang, Cee Ing Teh, and LaiFa Cao. "Critical state strength parameters of saturated clays from the modified Cam clay model." Canadian Geotechnical Journal 36, no. 5 (November 23, 1999): 876–90. http://dx.doi.org/10.1139/t99-050.
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The evaluation of critical state strength parameters is important, especially with the introduction of limit state design. The modified Cam clay (MCC) model is often used, but it is suitable mainly for evaluating the critical state strength parameters from triaxial compression tests on isotropically consolidated soils. The initial stress condition of a natural soil is usually anisotropic, and the stress paths imposed by external loading could deviate from that of a simple triaxial compression. The use of MCC in practice deserves careful consideration. This paper describes a proposed extension of the MCC model for the evaluation of critical state strength parameters from undrained triaxial and plane strain tests on anisotropically consolidated clays. Using Lade's failure criterion and the plastic potential of MCC, a generalized yield surface is determined and the relationships between the critical state internal friction angles from various triaxial and plane strain tests are obtained. By relating the isotropic overconsolidation ratio to the conventional overconsolidation ratio (OCR), a procedure is suggested for the prediction of critical state undrained shear strength (su) for clays. The undrained strength normalized by the preconsolidation pressure is not a constant but a function of the angle of internal friction and the OCR. For overconsolidated clay, the predicted undrained strength ratio (su/σVO) for the triaxial compression condition is larger than that for the plane strain compression condition. Comparisons of predicted results with published data indicate that the procedure is applicable to various compression tests on normally and lightly to moderately overconsolidated clays. Key words: stress anisotropy, clay, constitutive model, critical state, laboratory test, shear strength parameters.
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Alinaghizadeh, Farhad, and Mahmoud Shariati. "Buckling Analysis of Variable Thickness Radially Functionally Graded Annular Sector Plates Resting on Two-Parameter Elastic Foundations by the GDQ Method." International Journal of Applied Mechanics 07, no. 06 (December 2015): 1550083. http://dx.doi.org/10.1142/s1758825115500830.
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In this paper, buckling analysis of thick radially functionally graded circular/annular sector plates with variable thickness resting on two-parameter elastic foundations is studied. The material properties vary along radial direction according to either an exponential or a power-law distribution. The stability equations are derived using the adjacent equilibrium criterion and are based on a higher order shear deformation theory. The generalized differential quadrature method is employed to discretize the stability equations and convert them into a system of algebraic eigenvalue problem. The formulation and method of solution are validated by performing comparison studies with the available results in the open literature. Then, the effects of power-law index, boundary conditions, thickness variation and coefficients of foundation on the critical buckling load of the circular/annular sector plates subjected to different types of in-plane compressions or in-plane shear are investigated in detail.
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Roy, A. K., and S. W. Tsai. "Design of Thick Composite Cylinders." Journal of Pressure Vessel Technology 110, no. 3 (August 1, 1988): 255–62. http://dx.doi.org/10.1115/1.3265597.
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A simple and efficient design method for thick composite cylinders is presented. Micromechanics and macromechanics are integrated by simple relations and the integrated micro and macromechanics approach has been adopted to enable the designers to instantly study the sensitivity of the micromechanical variables on the final design. The stress analysis is based on 3-dimensional elasticity by considering the cylinder in the state of generalized plane strain. The analysis for both open-ended (pipes) and closed-ended (pressure vessels) cylinders subjected to internal and external pressures and axial load is presented. The failure of the cylinders is predicted by using a 3-dimensional quadratic failure criterion. A degradation model is used to calculate burst pressures and the calculated burst pressures agree very well with the available experimental results, for both thin and thick cylinders. In optimizing multilayer cylinders, the 3-D quadratic criterion enables one to obtain the optimal layer sequence very easily. It is found that the layer sequence is very critical in optimizing, in particular, thick cylinders. In addition, the design parameters and material use efficiency of multilayer closed cylinders subjected to internal pressure have also been studied.
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Nakhmanson, G. S., V. S. Kostennikov, and D. A. Nitsak. "Significance Level and the Strength of Test Shift Through the Finite Rate of the Transient Response." Ural Radio Engineering Journal 6, no. 4 (2022): 378–89. http://dx.doi.org/10.15826/urej.2022.6.4.002.
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A significance level and the strength of test shifts are studied then the error function as a transient response model of logical gate is used for testing of statistical hypothesis with Neumann-Pearson criterion. Shifts are rated for Rayleigh accumulated distributions. The generalized signalto-noise ratio is used as one of the variable parameters. The paper reveals that the finite slope of the transient response curve of logical gate results in a type I error increase. The significance level lock leads to bottom of critical region increase and the strength of test decrease in return. The twofold increase of the slope of the transient response curve leads to both the type I error and the bottom of critical region and the strength of test shifts decrease about 12 dB. The twofold increase of generalized signal-to-noise ratio causes the rise of the maximum displacement of a test power functions more than 3 dB up. As this takes place the extremum abscissa is diminished.
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Craciun, Eduard Marius, Adrian Carabineanu, and Niculae Peride. "Fracture Analysis of an Oblique Crack Propagation in a Pre-Stressed Glass-Epoxy Composite." Key Engineering Materials 385-387 (July 2008): 733–36. http://dx.doi.org/10.4028/www.scientific.net/kem.385-387.733.
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We consider a pre-stressed material containing an oblique crack of a length 2a situated in x1x3 plane. We supposed that the material is unbounded and the crack faces are acted by constant normal incremental stresses p. The initial applied stress ◦ is in direction of the crack. Our first aim is to determine the elastic state produced in the body using Guz’s representation theorem. Our second aim is to determine the critical values of the incremental stresses and the direction of crack propagation. To do this, we use Sih’s generalised fracture criterion for an orthotropic elastic composite. In the last part we find the critical values of the initial applied stress ◦ for which the phenomenon of resonance can appear in a pre-stressed Glass-Epoxy composite.
Dissertations / Theses on the topic "Generalized critical plane criterion"
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Warneboldt, Iona. "Multiaxial fatigue design of elastomeric parts using Equivalent Fatigue Loads." Electronic Thesis or Diss., Brest, École nationale supérieure de techniques avancées Bretagne, 2022. http://www.theses.fr/2022ENTA0002.
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Trois étapes sont mises en oeuvre ici : la méthode de localisation, la fonction de dommage matériau et le processus de détermination des chargements équivalents en fatigue (CEF). De nombreux essais de fatigue ont été réalisés (415 au total) pour étudier le comportement en fatigue sous chargement multiaxial relaxant et non relaxant sur des éprouvettes de caoutchouc naturel. La durée de vie et les caractéristiques des fissures sont analysées pour finalement introduire un critère de fatigue approprié basé sur le plan critique et permettant de rendre compte de l'effet de déformation moyenne. Ce critère est généralisé à travers une méthode originale de recherche du plan critique. Pour estimer la réponse mécanique locale (méthode de localisation), une méthode de couplage des axes adaptée à la nature non linéaire des structures élastomères est proposée. Elle est basée sur la décomposition multiplicative des tenseurs du gradient de la déformation. Ces deux étapes sont ensuite mises en oeuvre dans le cadre du processus de détermination du CEF. Pour cela, une méthode d'optimisation globale est ajoutée pour déterminer les chargements simplifiés, induisant partout localement le même endommagement en fatigue dans la structure étudiée que le RLD. Le temps de calcul de cette optimisation est réduit en ne considérant qu'un sous-ensemble de points matériels, les plus endommagés, pour la détermination du CEF. Enfin, la méthode a été testée sur une éprouvette afin de souligner ses capacités et de valider l'approcheThis thesis introduces an Equivalent Fatigue Load (EFL) approach for the multiaxial fatigue design of elastomeric parts. As direct Finite Element Analysis (FEA) calculations of automotive in-service loads (Road Load Data (RLD)) are too expensive, the objective is to derive simplified load blocks as a realistic input for numerical damage calculations. Three streps are applied for this method: the localization method, the material damage function and the EFL determination process. Various fatigue tests have been conducted (415 samples) to study the fatigue behavior of this complex type of relaxing and non-relaxing multiaxial loading on natural rubber specimens. Lifetime and crack features are analyzed to eventually introduce an appropriate critical planebased fatigue measure and to establish a novel mean strain effect model. This criterion is generalized throughout an original critical plane search method. To estimate the local mechanical response (localization method), this thesis identifies an axes-coupling method that is fitted for the nonlinear nature of elastomeric structures. It is based on the multiplicative decomposition of the deformation gradient tensors. These two steps are then implemented in the framework of the EFLdetermination process. For this, a global optimization method is added to determine the simplified load blocks, causing locally the same fatigue behavior in the given structure. The computational costs of this optimization are reduced by only considering a subset of the most damaged material points for EFLdetermination. Finally, the method has been challenged on a specimen to outline its capabilities and to validate the approach
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Tangtragulwong, Potchara. "Optimal Railroad Rail Grinding for Fatigue Mitigation." Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8909.
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This dissertation aims to study the benefit of rail grinding on service life of railroad rails, focusing on failures due to rolling contact fatigue (RCF) at the rail head. Assuming a tangent rail with one-point contact at the running surface, a finite element analysis of a full-scale wheel-rail rolling contact with a nonlinear isotropic kinematic hardening material model is performed to simulate the accumulation of residual stresses and strains in the rail head. Using rolling stress and strain results from the sixth loading cycle, in which residual stresses and strains are at their steady-state, as input, two critical plane fatigue criteria are proposed for fatigue analyses. The first fatigue criterion is the stress-based approach—namely the Findley fatigue criterion. It suggests an important role of tensile residual stresses on subsurface crack nucleation and early growth in the rail head, but applications of the criterion to the near-running-surface region are limited because of plastic deformation from wheel-rail contact. The second fatigue criterion is the strain-based approach—namely the Fatemi-Socie fatigue criterion. Contributed mainly from shear strain amplitudes and factorized by normal stress components, the criterion also predicts fatigue crack nucleation at the subsurface as a possible failure mode as well as fatigue crack nucleation at the near-surface, while maintaining its validity in both regions. A collection of fatigue test data of various types of rail steel from literature is analyzed to determine a relationship between fatigue damages and number of cycles to failure. Considering a set of wheel loads with their corresponding number of rolling passage as a loading unit (LU), optimizations of grinding schedules with genetic algorithm (GA) show that fatigue life of rail increases by varying amount when compared against that from the no-grinding case. Results show that the proposed grinding schedules, optimized with the exploratory and local-search genetic algorithms, can increase fatigue life of rail by 240 percent. The optimization framework is designed to be able to determine a set of optimal grinding schedules for different types of rail steel and different contact configurations, i.e. two-point contact occurred when cornering.
Book chapters on the topic "Generalized critical plane criterion"
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Deville, Michel O. "Instability." In An Introduction to the Mechanics of Incompressible Fluids, 197–210. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-04683-4_8.
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AbstractThe first instability mechanism is applied to the plane parallel channel flow. We establish the well known Orr-Sommerfeld equation which is solved by the Chebyshev Tau method. The associated Fortran programme is given in the appendix. Then the stability of the circular Couette flow between two concentric cylinders is undertaken. The inviscid approach yields the Rayleigh stability criterion. The incorporation of the viscous and pressure terms generates through a linearization process a set of differential equations again solved by high-order discretization methods through a generalized eigenvalue problem. The chapter ends with the case of the non-linear axisymmetric Taylor vortices.
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Zinn-Justin, Jean. "Large order behaviour of perturbation theory." In Quantum Field Theory and Critical Phenomena, 960–74. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198834625.003.0040.
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In quantum field theory (QFT), the main analytic tool to calculate physical quantities is the perturbative expansion. Following, Dyson's intuitive argument, the divergence of perturbative series was demonstrated in some models of quantum mechanics (QM) with polynomial potentials, using the Schrödinger equation. Later, it was proposed to study the problem within a path integral formulation. A systematic method in field theory was proposed by Lipatov, using the field integral representation of the φ4 4 field theory and instantons. It can be shown that the ground-state energy of the quartic anharmonic oscillator is analytic in a cut-plane. The imaginary part of the energy on the cut is related to barrier penetration. The behaviour of the perturbative coefficients at large orders is related to the behaviour of the imaginary part for small and negative coupling and can be obtained by instanton methods. The method has been generalized to the class of potentials for which (in general complex) instanton contributions have been calculated. The same method can be readily applied to boson field theories, while the extension to field theories involving fermions, like Quantum QED, requires additional considerations. The general conclusion is that, in QFT, all perturbative series, expanded in terms of a loop-expansion parameter, are divergent series.
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Dutta, Dhiman, and Mausumi Sen. "Fixed Charged Solid Transportation Problem With Budget Constraints in Type-2 Fuzzy Variables." In Soft Computing Techniques and Applications in Mechanical Engineering, 35–71. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-3035-0.ch002.
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A multi-objective fixed charged solid transportation model with criterion e.g. transportation penalty, amounts, demands, carriages and budget constraints as type-2 triangular fuzzy variables with condition on few components and carriages is proposed here. With the critical value based reductions of corresponding type-2 fuzzy variables, a nearest interval approximation model and a chance constrained programming model applying generalized credibility measure for the constraints is proposed for this particular problem. The credibility measure is also applied to the objective functions of the chance constrained programming model. The model is then transformed into the corresponding crisp deterministic form by these two methods. A numerical example is provided to explain the model with hypothetical data and is then worked out by applying a gradient based optimization - Generalized Reduced Gradient technique (applying LINGO 16). The corresponding objective function values are compared numerically by two approaches after transforming it to crisp form by these two methods.
Conference papers on the topic "Generalized critical plane criterion"
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Zaitsev, Dmitry, Andrey Semenov, and Oleg Kabov. "Viscosity Effect on Thermocapillary Rupture of Falling Liquid Films." In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-23222.
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Rupture of a subcooled liquid film flowing over an inclined plate with a 150×150 mm heater is studied for a wide range of liquid viscosity (dynamic viscosity μ = (0.91–17.2)x10−3 Pa·s) and plate inclination angle with respect to the horizon (Θ = 3–90 deg). The main governing parameters of the experiment and their respective values are: Reynolds number Re = 0.15–54, heat flux q = 0–224 W/cm2. The effect of the heat flux on the film flow leads to the formation of periodically flowing rivulets and thin film between them. As the heat flux grows the film thickness between rivulets gradually decreases, and, upon reaching a certain threshold heat flux, qidp, the film ruptures in the area between the rivulets. The threshold heat flux increases with the flow rate of liquid and with the liquid viscosity, while the plate inclination angle has little effect on qidp. Criterion Kp, which is traditionally used in the literature to predict thermocapillary film rupture, was found to poorly generalize data for high viscous liquids (ethylene glycol, and aqueous solutions of glycerol) and also data for Θ≤45 deg. The criterion Kp was modified by taking into account characteristic critical film thickness for film rupture under isothermal conditions (no heating), deduced from existing theoretical models. The modified criterion has allowed to successfully generalize data for whole ranges of μ, Re, Θ and q, studied.
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Idell, Paul S. "Optimal imaging concentrators based on the ratio of encircled energy criterion." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/oam.1986.thh1.
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We investigate the effects of spatial coherence on the design of optimal imaging concentrators where the ratio of encircled energy (REE) in the image plane is used to gauge concentrator performance. Using the REE criterion, we develop an apodization procedure which provides optimal light concentration for source fields possessing arbitrary states of spatial coherence and for arbitrary detector configurations. Our solution for the optimal pupil screen invokes the use of a generalized Fredholm-type integral equation whose integral kernel (and weighting function) are determined by the pupil field cross-spectral density function and the detector configuration in the image plane. We illustrate the effects of source coherence on the optimal apodizer design through the use of several numerically computed examples. These examples indicate the range of field coherence conditions over which concentrator performance will be improved through apodization. For the case that multiple-detector concentrators are considered, we investigate the onset of eigenvalue degeneracy in the integral eigenvalue problem and discuss its effects on the optimal pupil function solution.
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Kamal, S. M., and Faruque Aziz. "Estimation of the Stresses in Rotational Autofrettage of Thick-Walled Pressure Vessels Using von Mises Yield Criterion." In ASME 2021 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/pvp2021-61888.
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Abstract Rotational autofrettage is one of the recently proposed potential methods for eliminating the in-service yielding of thick-walled cylindrical pressure vessels. A few researchers have studied the feasibility of the process theoretically, and asserted certain advantages over the practicing hydraulic and swage autofrettage processes. In the literature, all theoretical analyses on the rotational autofrettage are based on the Tresca yield criterion and its associated flow rule, along with the assumption of different plane end conditions (plane strain and generalized plane strain). In this paper, an analysis of the rotational autofrettage of cylindrical vessel is attempted incorporating von Mises yield criterion. The plane strain condition is used for the analysis. A numerical shooting method is used to solve the governing differential equations providing the elastic-plastic stress distributions in the cylinder during loading. The present procedure is numerically experimented for a typical AH36 pressure vessel. It is found that the achievable level of the maximum stress pressure of the rotationally autofrettaged vessel is 74.46% higher than that of its non-autofrettaged counterpart for an overstrain level of 46.7%.
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Yano, Takeru, Shigeo Fujikawa, and Tao Yu. "Reconsideration of Cavitation Inception Theory." In ASME/JSME 2007 5th Joint Fluids Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/fedsm2007-37177.
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The nonlinear dynamics of a spherical gas bubble in a liquid water is reconsidered on the basis of the Rayleigh-Plesset equation with particularly emphasis on the unstable behavior with respect to infinitesimal perturbations. The evolution of bubble radius after the discontinuous change of ambient pressure is theoretically analyzed, and the classical critical pressure and critical radius are re-derived as a saddle-node bifurcation point, when the center and saddle on the phase plane merge into a degenerate unstable singular point in the phase plane. Before the saddle-node bifurcation, there is a separatrix issuing from and entering into the saddle point in the inviscid limit. We propose a new criterion for cavitation inception: the ambient pressure that makes the separatrix pass through the initial bubble radius. This criterion gives a cavitation inception pressure higher than the classical one. The effects of viscosity and thermal conductivity are also discussed.
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Jiang, Yanyao, Tianwen Zhao, Xiaogui Wang, and Zengliang Gao. "Multiaxial Fatigue of 16MnR Steel." In ASME 2006 Pressure Vessels and Piping/ICPVT-11 Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/pvp2006-icpvt-11-93473.
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Uniaxial, torsion, and axial-torsion fatigue experiments were conducted on a pressure vessel steel, 16MnR, at room temperature. The uniaxial experiments were conducted using solid cylindrical specimens. Axial-torsion experiments employed thin-walled tubular specimens subjected to proportional and nonproportional loading. A critical plane multiaxial fatigue criterion recently developed was found to correlate well with all the experiments conducted for the material. In addition, the fatigue criterion correctly predicted the cracking behavior of the material subjected to different loading paths.
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Meshii, Toshiyuki, and Kai Lu. "Applicability of a Deterministic Approach to Transfer the Fracture Toughness Jc Between Different Specimen Thicknesses." In ASME 2015 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/pvp2015-45071.
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In this paper, validity of the deterministic approach to transfer the fracture toughness Jc obtained with different thickness specimens was demonstrated. For this purpose, applicability of the (4δt, σ22c) failure criterion [1] was verified to transfer Jcs obtained for different specimen thicknesses in the fracture toughness database obtained from decommissioned Shoreham reactor vessel steel [2, 3]. The material tested was ASTM A533 Grade B Class 1 ferritic steel tested in the ductile-to-brittle transition temperature region. The critical value σ22c for twelve types of specimens (thickness in the range of 8 to 254 mm) showed only 4% variation. The fact that these critical values were always reached at the specimen mid-plane and the fact that cleavage always initiated at the specimen mid-plane supported the validity of the deterministic approach. Because the (4δt, σ22c) failure criterion requires only “single” set of test data for Jc transfer and because σ22c shows only a few % scatter, it seems to have a possibility to replace what Weibull stress is expected to do.
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Bottega, W. J., and S. E. Rutgerson. "Thermo-Mechanical Instabilities in Bilaminate Shell Structures." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/ad-23770.
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Abstract The problem of an elastic bilaminate shell subjected to transverse pressure and a uniform temperature field is considered for plane strain/plane stress configurations. Closed form analytical solutions are obtained for the nonlinear problem, and a stability criterion is derived for situations where multiple equilibrium configurations of the structure are possible for a given value of the loading parameter (a combination of the normalized pressure and thermal moment). Critical behavior is seen to be dependent on two critical parameters, a critical value of the loading parameter and a critical value of the membrane force. Extensive numerical simulations based on these solutions reveal characteristic behavior of the system. This behavior includes, bifurcation buckling, asymptotic buckling, sling-shot buckling and pre-limit point snap-through buckling. It is seen that pre-limit point snap-through is pervasive and perhaps the norm, even for certain classic problems, and its degree is a function of the material properties of the structure.
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Jacquemoud, C., S. Marie, and M. Nédélec. "Modelling the Graphite Fracture Mechanisms." In ASME 2012 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/pvp2012-78371.
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In order to define a design criterion for graphite components, it is important to identify the physical phenomena responsible for the graphite fracture, to include them in a more effective modelling. In a first step, a large panel of experiments have been realised in order to build up an important database; results of tensile tests, 3 and 4 point bending tests on smooth and notched specimens have been analysed and have demonstrated an important geometry related effects on the behavior up to fracture. Then, first simulations with an elastic or an elastoplastic bilinear constitutive law have not made it possible to simulate the experimental fracture stress variations with the specimen geometry, the fracture mechanisms of the graphite being at the microstructural scale. That is the reason why a specific F.E. model of the graphite structure has been developed in which every graphite grain has been meshed independently, the crack initiation along the basal plane of the particles as well as the crack propagation and coalescence have been modelled too. This specific model has been used to test two different approaches for fracture initiation: a critical stress criterion and two criteria of fracture mechanic type. They are all based on crystallographic considerations as a global critical stress criterion gave unsatisfactory results. The criteria of fracture mechanic type being extremely unstable and unable to represent the graphite global behaviour up to the final collapse, the critical stress criterion has been preferred to predict the results of the large range of available experiments, on both smooth and notched specimens. In so doing, the experimental observations have been correctly simulated: the geometry related effects on the experimental fracture stress dispersion, the specimen volume effects on the macroscopic fracture stress and the crack propagation at a constant stress intensity factor. In addition, the parameters of the criterion have been related to experimental observations: the local crack initiation stress of 8MPa corresponds to the non-linearity apparition on the global behavior observed experimentally and the the maximal critical stress defined for the particle of 30MPa is equivalent to the fracture stress of notched specimens. This innovative combination of crack modelling and a local crystallographic critical stress criterion made it possible to understand that cleavage initiation and propagation in the graphite microstructure was driven by a mean critical stress criterion.
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Walters, Carey L., and Lars O. Voormeeren. "Consequences of Using the Plane Stress Assumption for Damage Calculations in Crash Analyses." In ASME 2014 33rd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/omae2014-23946.
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Simulation of failure in plate materials (represented as shell elements) is critical for the correct determination of crash performance of ships and offshore structures. This need has traditionally been filled with failure loci that give the failure strain in terms of stress triaxiality. In recent years, a third dimension (Lode parameter) has been introduced in the form of the Modified Mohr Coulomb failure criterion and Lode parameter adjusted Gurson-type models. This development introduces ambiguity for shell structures, in which only two dimensions are represented. The typical way of addressing this is to assume that shell structures fail in plane stress, thus reducing the problem back to 2-D. However, the assumption of plane stress is violated as soon as necking begins, causing different stress triaxialities and Lode parameters than would be expected from the planar case. More importantly, the inhomogenous necked region is then homogenized over the entire shell element. In this paper, the consequences of the through-thickness plane stress assumption are assessed through a finite element model of a plate that is subjected to a far-field stress.
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Qiu, Baoxiang, Zengliang Gao, Xiaogui Wang, and Yanyao Jiang. "Prediction of Fatigue Initiation Life of 16MnR Notched Components." In ASME 2007 Pressure Vessels and Piping Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/pvp2007-26779.
Full textAbstract:
Fatigue initiation life of smooth and notched rod 16MnR specimens subjected to fully reversed uniaxial tension-compression and pure torsion cyclic loading was studied by a multiaxial fatigue damage criterion. A robust cyclic plasticity model was implemented into ABAQUS via a user-material subroutine UMAT. In virtue of the axisymmetry of geometry and loading, an axisymmetric model was facilitated to get the cyclic elasto-plastic stress-strain relationship. The accumulated fatigue damage of each material point in different material plane was then obtained by Jiang’s fatigue damage criterion. From the results of fatigue damage analysis we know that the maximum stabilized damage per loading cycle was at the root of the notch, where the material point firstly reaches the critical damage value. Fatigue crack initiation life is defined as the ratio of the critical damage to the maximum fatigue damage per loading cycle. Uniaxial and pure torsion fatigue experiments for the smooth rod specimens, sharp and blunt notched rod specimens were also conducted. Good agreement was achieved by comparing the predicted fatigue initiation life with the experiment results.