Implicit integration in soil plasticity under mixed control for drained and undrained response

Abstract

An algorithm is outlined for the implicit integration of isotropic plasticity models for an arbitrary choice of mixed stress and strain control variables. Drained as well as undrained behaviour is considered. The closest-point-projection method in conjunction with a completely strain-driven format is used in a core algorithm. In the drained case strain response variables are determined via iterations to satisfy equilibrium of prescribed and calculated stresses that correspond to the strain response variables. In the undrained case, on the other hand, strains and pore pressure are determined via simultaneous iterations to satisfy equilibrium and the incompressibility condition. The algorithm is applied to a new generalized cam-clay model, and various iteration techniques are assessed. In particular, Newton iterations which employ the matrix of algorithmic tangent stiffness moduli are shown to compete favourably with more conventional methods.

A constitutive model for granular materials with grain crushing and its application to a pyroclastic soil

“…The scalar χ may be, in general, state dependent. However, to keep the formulation of the model as simple as possible, in the following it will be assumed, as in [2], that:…”

Optimization routine for identification of model parameters in soil plasticity

“…These parameters will then give the in advance known solution of the problem (the global minimum). The parameter values are mainly chosen from Alawaji et al [13]. Further, the problem is designed in such a way that the elastic parameters *"0.02 and "0.…”

“…The constitutive model chosen for this example is the generalized cam clay model, described in Reference [13]. The model is based on the classical modi"ed cam clay concept (see e.g.…”

“…But for the ACC model, it is promising to see that a reasonable agreement has been obtained also in the simultaneous optimization. In the simultaneous optimizations the combined norm in Equation (13) together with the absolute norm (without weighting) in Equation (7) have been used. However, maximum norm values are presented in Tables VIII and IX Tables VIII and IX, Tables VIII and IX were obtained for tests no.…”

Steady Flow of a Particulate Target Medium Over a Projectile: Experiments and Modeling

“…Doublesurface models such as the Drucker-Prager/cap elasto-plastic model have been used to describe ceramic powder stress-strain behavior (see Gethin et al (1994), Aydin et al (1996); Chtourou et al All the models discussed so far neglect the effect of the third stress invariant on the behavior. Yet, there is experimental evidence showing that all three principal stresses, 1 σ , 2 σ , 3 σ (or equivalently all three stress invariants) influence the deformation and failure of particulate systems (see for example, Bardett and Lode, 1990;Peric and Ayari, 2000;Alawaji et al (1992); Lade and Kim (1995), Saxena et al (1988), Verwijs et al(2002), etc.). Several models for granular materials that make use of yield functions, flow potentials, and failure conditions involving the third stress invariant were proposed by Lade and co-workers (e.g.…”