Engineering analysis + design software

User Area > Advice

Typical warning message found in the LUSAS Solver text output (*.OUT) file:

***WARNING*** SOME ELEMENTS WITH ECCENTRIC GEOMETRIC PROPERTIES HAVE BEEN ASSIGNED A NONLINEAR MATERIAL STATE VARIABLES SUCH AS PLASTIC STRAINS WILL BE EVALUATED USING STRESS RESULTANTS COMPUTED AT THE NODAL LINE AND NOT AT THE BEAM CROSS SECTION (KBTS6 PROCESSOR)


Most common causes & links to solutions 

This warning is to inform the user that plastic strains are evaluated using stress resultants computed at the nodal line and not at the beam eccentric cross-section.

Using the Stress Resultant material model for beams, the whole section will yield instantaneously and, as such, cannot be considered to yield only at an extreme fibre location with the section therefore partially yielded. The whole cross-section is considered as either fully elastic, or completely plastic. For this reason, stresses at extreme fibre locations may exceed the yield stress. For further details of this material model and its yield criterion, please see:

Theory Manual Volume 1 > Chapter 4 : Constitutive Models > 4.3 Plasticity Models for Beams and Shells > 4.3.2 Resultant Model 

The plastic strains will be given at the nodal line. The yield criterion considers axial forces, moments, torsions and shears where the values computed at the nodal line rather than the neutral axis will be used for checking the yield. Moment and force values at the neutral line could be different to the values at the eccentric section and thus the input plastic section properties and the values used could cause some approximation in the initiated yield.

 


innovative | flexible | trusted

LUSAS is a trademark and trading name of Finite Element Analysis Ltd. Copyright 1982 - 2022. Last modified: November 29, 2022 . Privacy policy. 
Any modelling, design and analysis capabilities described are dependent upon the LUSAS software product, version and option in use.