A modified strain rate dependent constitutive model for chalk and porous rock

Abstract

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A Strain Rate‐Dependent Constitutive Model for Asymmetric Hardening Behavior of TB9 Titanium Alloy

“…, where ε ij is strain tensor. [30] The fracture morphology of tensile samples is characterized and observed by SEM, as shown in Figure 3. It can be seen that the fracture morphology has typical ductile fracture characteristics.…”

Effects of Porosity and Water Saturation on the Yield Surface of Upper Cretaceous Reservoir Chalks From the Danish North Sea

“…The material parameters controlling the locus and shape of the elliptical end cap in p′ m -q plots are based on empirical data and account for lithology, type of saturating fluid, stress conditions and time (Angus et al, 2015;Cassiani et al, 2017;Hickman & Gutierrez, 2007;Vejbaek et al, 2014). Almost all constitutive models use these two kind of yield surfaces independently for shear and pore collapse deformation (Hajiabadi & Nick, 2020). Computing the stress-strain state of a rock near the intersection between the two yield functions can cause problems for numerical simulations.…”

Consistent Implicit Time Integration for Viscoplastic Modelingof Subsidence above Hydrocarbon Reservoirs

“…In the following derivations, the isotropic elastic tensor D is considered constant in the time step, as is commonly assumed in the literature; see, e.g., [20]. Its value will be updated based on Equation (7) only at the end of the considered time step. An implicit formulation of the algorithm considering also the evolution of D within the time step would be possible, at the cost however of additional complications in the formulation of the integration scheme and of the consequent increase of the computing time, with little expected improvement of accuracy.…”

“…The several stress-strain time-dependent models for soils that have been presented in the literature mainly fall within the following two main categories:(i) models based on the concept of overstress and (ii) models based on nonstationary yield theory, where the classical plasticity yield limit is generalized to a viscoplastic yield locus that depends on a time-dependent function, see e.g., [6,7] and the reviews in [8,9]. By following the overtress approach, the Vermeer-Neher (V-N) model [10,11], which addresses materials with a high degree of compressibility, such as soft soils, and generalizes odometer test results to fully three-dimensional conditions accounting also for (secondary) creep through an elastic-viscoplastic model, has encountered a significant popularity and is still actively used in the oil and gas industry for subsidence modeling, to predict the deformation of the ground surface induced by hydrocarbon withdrawal from underground reservoirs.…”