Ductile Fracture Instability in Shear

Abstract It is postulated that fracture occurs in an elastic-plastic, nonwork-hardening material subject to pure shear when a critical shear strain is attained throughout a critical volume of material. This postulate is combined with the classical equations of plasticity to predict when cracking will initiate from a notch at nominal shear stresses below the yield stress, when the crack will become unstable on increase of stress, and when unstable cracking will occur if a notch is cut while a constant nominal stress is maintained. Tests on aluminum foil under biaxial tensile stress show results similar to those predicted by the theory.

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Stress in Metal Foils During Processing and Thermal Cycling.

MRS Proceedings ◽

10.1557/proc-226-197 ◽

1991 ◽

Vol 226 ◽

Cited By ~ 1

Author(s):

A. Jagota ◽

M.F. Lemon ◽

Y.H. Hu

Keyword(s):

Thermal Expansion ◽

Tensile Stress ◽

Yield Stress ◽

Stress Measurement ◽

Vibrational Analysis ◽

Aluminum Foil ◽

Thermal Expansion Mismatch ◽

Metal Foils ◽

Grain Sizes ◽

Wide Range

AbstractThe vibrational technique for stress measurement in films has been used to study silver foils, silver-based conductor pastes, and aluminum foil. During cooling, a tensile stress develops in the films due to thermal expansion mismatch with the substrate. Because the stress is limited by the yield stress, these experiments furnish data for the yield stress of the materials over a wide range of temperature at fixed state. Experiments with silver specimens pre-annealed to different grain sizes show that the yield stress follows the Hall-Petch relationship. The full vibrational analysis is used to extract the stiffness of the foils.

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A Monotonic Smeared Truss Model to Predict the Envelope Shear Stress—Shear Strain Curve for Reinforced Concrete Panel Elements under Cyclic Shear

Applied Mechanics ◽

10.3390/applmech2010011 ◽

2021 ◽

Vol 2 (1) ◽

pp. 174-194

Author(s):

Luís Bernardo ◽

Saffana Sadieh

Keyword(s):

Shear Stress ◽

Reinforced Concrete ◽

Shear Strain ◽

Peak Load ◽

Strain Curve ◽

Fiber Reinforced Polymers ◽

Shear Stresses ◽

Cyclic Shear ◽

Concrete Panels ◽

Truss Model

In previous studies, a smeared truss model based on a refinement of the rotating-angle softened truss model (RA-STM) was proposed to predict the full response of structural concrete panel elements under in-plane monotonic loading. This model, called the “efficient RA-STM procedure”, was validated against the experimental results of reinforced and prestressed concrete panels, steel fiber concrete panels, and reinforced concrete panels externally strengthened with fiber-reinforced polymers. The model incorporates equilibrium and compatibility equations, as well as appropriate smeared constitutive laws of the materials. Besides, it incorporates an efficient algorithm for the calculation procedure to compute the solution points without using the classical trial-and-error technique, providing high numerical efficiency and stability. In this study, the efficient RA-STM procedure is adapted and checked against some experimental data related to reinforced concrete (RC) panels tested under in-plane cyclic shear until failure and found in the literature. Being a monotonic model, the predictions from the model are compared with the experimental envelopes of the hysteretic shear stress–shear strain loops. It is shown that the predictions for the shape (at least until the peak load is reached) and for key shear stresses (namely, cracking, yielding, and maximum shear stresses) of the envelope shear stress–shear strain curves are in reasonably good agreement with the experimental ones. From the obtained results, the efficient RA-STM procedure can be considered as a reliable model to predict some important features of the response of RC panels under cyclic shear, at least for a precheck analysis or predesign.

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Determination of the Biaxial Anisotropy Coefficient Using a Single Layer Sheet Metal Compression Test

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.883.303 ◽

2021 ◽

Vol 883 ◽

pp. 303-308

Author(s):

Peter Hetz ◽

Matthias Lenzen ◽

Martin Kraus ◽

Marion Merklein

Keyword(s):

Stress State ◽

Tensile Stress ◽

Sheet Metal ◽

Compression Test ◽

Test Procedure ◽

Rolling Direction ◽

Single Layer ◽

Material Behavior ◽

Biaxial Tensile ◽

Biaxial Tensile Stress

Numerical process design leads to cost and time savings in sheet metal forming processes. Therefore, a modeling of the material behavior is required to map the flow properties of sheet metal. For the identification of current yield criteria, the yield strength and the hardening behavior as well as the Lankford coefficients are taken into account. By considering the anisotropy as a function of rolling direction and stress state, the prediction quality of anisotropic materials is improved by a more accurate modeling of the yield locus curve. According to the current state of the art, the layer compression test is used to determine the corresponding Lankford coefficient for the biaxial tensile stress state. However, the test setup and the test procedure is quite challenging compared to other tests for the material characterization. Due to this, the test is only of limited suitability if only the Lankford coefficient has to be determined. In this contribution, a simplified test is presented. It is a reduction of the layer compression test to one single sheet layer. So the Lankford coefficient for the biaxial tensile stress state can be analyzed with a significantly lower test effort. The results prove the applicability of the proposed test for an easy and time efficient characterization of the biaxial Lankford coefficient.

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Calculations of energy band structure and mobility in critical bandgap strained Ge1-xSnx based on Sn component and biaxial tensile stress modulation

Acta Physica Sinica ◽

10.7498/aps.67.20171969 ◽

2018 ◽

Vol 67 (2) ◽

pp. 027101

Author(s):

Di Lin-Jia ◽

Dai Xian-Ying ◽

Song Jian-Jun ◽

Miao Dong-Ming ◽

Zhao Tian-Long ◽

...

Keyword(s):

Band Structure ◽

Tensile Stress ◽

Energy Band ◽

Energy Band Structure ◽

Biaxial Tensile ◽

Biaxial Tensile Stress

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Cyclic stress-strain data analysis under biaxial tensile stress state

Experimental Mechanics ◽

10.1007/bf02331111 ◽

1999 ◽

Vol 39 (2) ◽

pp. 92-102 ◽

Cited By ~ 11

Author(s):

A. Zouani ◽

T. Bui-Quoc ◽

M. Bernard

Keyword(s):

Data Analysis ◽

Stress State ◽

Tensile Stress ◽

Cyclic Stress ◽

Stress Strain ◽

Biaxial Tensile ◽

Strain Data ◽

Biaxial Tensile Stress

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Ductile Fracture under Tensile Stress in Structural Steel

Proceedings of The 7th International Conference On Fracture (ICF7) ◽

10.1016/b978-0-08-034341-9.50273-4 ◽

1989 ◽

pp. 3897-3904

Author(s):

Z.R. HE ◽

HE ZERONG ◽

L. ZHEN

Keyword(s):

Tensile Stress ◽

Ductile Fracture ◽

Structural Steel

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Investigation on shear strain of reinforced concrete membrane panels subjected to pure shear

Advances in Mechanical Engineering ◽

10.1177/1687814019869488 ◽

2019 ◽

Vol 11 (8) ◽

pp. 168781401986948

Author(s):

Je-Pyong Jeong ◽

Dae-Hung Kang

Keyword(s):

Reinforced Concrete ◽

Shear Strain ◽

Pure Shear ◽

Failure Criteria ◽

Principal Compressive Stress ◽

Strain Relationship ◽

Trial And Error Method ◽

Shear Strain Energy ◽

Relationship Of ◽

The Relationship

Hsu recently conducted a shear test on nine reinforced concrete panel elements subjected to applying pure shear using a shear testing device. Modern truss models (i.e. modified compression field theory and a rotating angle softened truss model) are used to perform a complex nonlinear analysis through a trial and error method based on a double loop. This analysis is conducted by employing equilibrium conditions, compatibility conditions, and a ductile stress–strain relationship of a reinforced concrete membrane panel in a biaxial state. In this study, an effective algorithm that uses a revised Mohr compatibility method based on the failure criteria of struts and ties is proposed. This algorithm is used to improve the convergence rate in the analysis of shear history, which was performed in the experiment of Hsu. The result of the analysis indicates that the shear strain energy in a state of extended shear strain is influenced by the relationship between principal compressive stress and strain (crushing failure).

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Internal Damper Characteristics of Rotor System with Submerged ER Fluid Journal Bearing

International Journal of Rotating Machinery ◽

10.1155/s1023621x97000079 ◽

1997 ◽

Vol 3 (1) ◽

pp. 61-71 ◽

Cited By ~ 3

Author(s):

Siyoul Jang ◽

John A. Tichy

Keyword(s):

Shear Stress ◽

Electric Field ◽

Shear Strain ◽

Yield Stress ◽

Electric Fields ◽

Journal Bearing ◽

Shear Strain Rate ◽

Newtonian Flow ◽

Damping Coefficients ◽

Er Fluid

Electro-Rheological (ER) fluid behavior is similar to Bingham fluid’ s. Only when the shear stress magnitude of ER fluid exceeds the yield stress, Newtonian flow results. Continuous shear strain rate equation about shear stress which simulates Bingham-like fluid shows viscosity variations. Shear yield stress is controlled by electric fields. Electric fields in circumferential direction around the journal are also changeable because of gap distance. These values make changes of spring and damping coefficients of journal bearings compared to Newtonian flow case. Implicit viscosity variation effects according to shear strain rates of fluid are included in generalized Reynolds' equation for submerged journal bearing. Fluid film pressure and perturbation pressures are solved using switch function of Elord's algorithm for cavitation boundary condition. Spring and damping coefficients are obtained for several parameters that determine the characteristics of ER fluids under a certain electric field. From these values stability region for simple rotor-bearing system is computed. It is found that there are no big differences in load capacities with the selected electric field parameters at low eccentric region and higher electric field can support more load with stability at low eccentric region.

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Exploring Mechanisms and Conditions for the Generation of Self-propagating Dykes

10.5194/egusphere-egu2020-12479 ◽

2020 ◽

Author(s):

Herbert Wallner ◽

Harro Schmeling

Keyword(s):

Yield Stress ◽

Shear Failure ◽

Source Region ◽

Shear Bands ◽

Shear Stresses ◽

Crustal Rock ◽

Stress Concentrations ◽

Magma Chambers ◽

Two Phase ◽

Matrix Extension

Within the scope of our project &#8220;Modelling melt ascent through the asthenosphere-lithosphere-continental crust system: Linking melt-matrix-two-phase flow with dyke propagation&#8221; it is necessary to implement mechanisms with appropriate conditions to generate dykes which are propagating independently.Conditions for self-propagating depend on the density contrast of melt and rock and the geometry of the fracture. Certain limits for the fluid-filled volume and dyke width must be reached. The height must be longer than the Bouguer length. To satisfy these conditions enough melt under overpressure must be available in the source region to supply the growing dyke.A known and accepted mechanism for dyke generation is a tension fracture whichs opening space immediately is filled by fluid melt. The normal stress due to expansion of the magma on the wallrock causes tension therein parallel to the melt front. In brittle material the yield stress for extension is very low and the confining cold rock easily cracks.With depth pressure, temperature and ductility of crustal rock and consequently the yield stress for the tensile cracking increases. Furthermore, the background permeability or connectivity, and finally the height of fluid columns decrease and the fluid overpressure is not high enough to exert matrix extension. Another dyke initiation mechnism must be found for the deeper parts of the crust.A not smooth melt front - and pillows are often seen on top of magma chambers &#8211; provides shear stresses and stress concentrations. Above a certain yield stress for shear failure shear bands start to evolve. In such a network of fracture zones permeability should increase. Melt may intrude, coalesce bands and develop a growing dyke. Such a local scenario will be modelled and results presented. A further aim is the parametrisation of these mechanisms.

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