UserCoded Material Models in ADINA One of the important goals in the development of ADINA is to provide an open and flexible environment for users to implement their own routines to meet their individual and industryspecific needs. In the ADINA News of Nov. 15, 2005, we provided a brief overview of the user programmable capabilities in ADINA Structures, ADINA Thermal and ADINA CFD. Now we focus more on the usercoded material models in ADINA Structures. Here is a list of some of the usercoded material models provided as examples with the ADINA installation CD to help users implement their own models:
Of course, some of the models are also in the standard ADINA material library. As an example of another usercoded material model, we present below an application of a nonlinear isotropic elastic material model that can be particularly useful when experimental uniaxial stressstrain data is available. In the material model, loading and unloading follow the same curve so no permanent inelastic strain is present, but different stressstrain behaviors in tension and compression are included. Also, tension or compression cutoff can be modeled. We use the model with the uniaxial stressstrain data for concrete, see Figure 1. The model captures some basic features of the nonlinear behavior of concrete but does not include the permanent loss of stiffness due to cracking or crushing. Rebars can be included as usual in the analysis. Figure 1 shows a simply supported beam with a box crosssection, loaded with a linearly varying lateral pressure. Only half of the beam is modeled with appropriate symmetry boundary conditions. The concrete beam is reinforced with pretensioned rebars, and as a result, the cross section of the beam is initially under compression.
The above movie shows the variation of the 'effective stress' in elements 1 and 2 (see Figure 1)
as the external load changes. The effective stress is defined as usual, see Ref., but
the sign is determined by the mean stress. In both elements the stress is initially
compressive, due to pretension in the rebars, but as the load increases, the stress
in element 1 remains compressive while the stress in element 2 becomes tensile.
This is a simple example of the material models that users can implement in ADINA through the usercoded material model option, but it illustrates how ADINA can be used flexibly in many applications.
