Drucker-Prager model

It may be shown that if one fits the Drucker-Prager model directly to concrete... 

The finite element analysis was performed using DIANA. The Drucker Prager model with associated plasticity was selected to model the concrete material. To satisfy the associative plasticity requirements, the values of O and xj/ were taken to be the same and equal to 10°. However, by using the 10°-degree-based associated... 

A more sophisticated model can be built from the Drucker-Prager s cone by introducing a dependence on the Lode s angle /I, in order to match more closely the Mohr-Coulomb criterion. It consists of a smoothed Mohr-Coulomb plasticity surface. The formulation based on the idea of Van Eekelen (1980) is used. It can be written in a very similar way to the Drucker-Prager s criterion ... 

In the following example we illustrate the first type of use of the second thermodynamic principle discussed in Section 6, namely, by verifying a constitutive model of EPS geofoam a posteriori for thermodynamic consistency. This model was developed by the authors (Wong and Leo, 2006) based on experimental results from a series of standard "drained" tiiaxial tests. It initially adopted the Mohr-Coulomb yield function used widely in soil mechanics but upon further testing with a true triaxial apparatus (Leo et al., 2008), a Drucker-Prager type yield function was subsequently preferred. This is written as ... 

Material properties for concrete include ft = 0.73 MPa at 28 days, c = 2.15 MPa (calibrated to match experimental data and lower than that determined from Eq. (13.4c)), 0 = P = 10°. Several researchers have used the angle of internal friction 30° when using Drucker-Prager yield criteria for modeling concrete. In this... 

Bulk tensile testing has shown that adhesives generally exhibit plasticity and, hence, nonlinear material properties are required to model their behavior over the fiill load range. Nonlinear properties may also be required for adherends. Thus, a combination of elasto-plastic material models may be used to predict the behavior of adhesive joints under load. The definition of the yield surface is important when using elasto-plastic material models. Von Mises yield surface is commonly used for the analysis of metals, which assumes that the yield behavior is independent of hydrostatic stress. As a result, the yield surface is identical in tension and compression. However, the yield behavior of polymers has been shown to exhibit hydrostatic stress dependence (Ward and Sweeney 2004) as the yielding starts earlier in tension than in compression. Thus, a yield criterion which includes hydrostatic stress effects should be used to determine the yield surface. Various yield criteria with hydrostatic stress dependence such as Drucker-Prager, Mohr-Columb, and modified Drucker-Prager/cap plasticity model have been implemented in commercially available finite element software. 

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