What’s new in Abaqus 2019 non-linear mechanics solver

2019 solver has number of enhancements that spans from fracture mechanics to element formulation to material formulation. Let’s start with what’s there on the fracture mechanics side:

Fracture mechanics enhancements

• Introduction of new linear elastic fatigue crack growth procedure: Allows for change in contact conditions while loading, allows non-linear geometry behavior, mixed mode fatigue loading and viewer improvement. It is currently available for constant amplitude loading only. The input deck for mixed mode behavior looks as follows:

• Improvements in contour integrals pre-processing and solving time. This applies to both J-integrals as well as K-integrals.
• XFEM improvement to increase smoothness of 3D non-planar crack front. This is achieved by introducing non-local stress averaging algorithms to predict crack direction. Also limit new crack propagation direction to a certain angle from previous direction.

• Symmetric cohesive elements have been introduced. Plane of symmetry must be perpendicular to one of the global axis though.

• Introduction of UDMGINI subroutine to incorporate varied crack initiation criteria for different enrichment zones.

Element technology enhancements

• Poro-elastic acoustic elements have been introduced to study wave propagation in coupled isotropic poro-elastic medium. It is only available in steady state dynamics analysis.
• Displacement acoustics pressure elements have been introduced: C3D8A, C3D6A, C3D4A. Primary unknows are structural displacement and pore pressure. Same shape function used for displacement and pressure.
• Shear panel element SHEAR4 in Abaqus has been introduced to model thin reinforced panels such as in fuselage. Intended to model response of buckled plate. Use is limited to linear elastic only.
• Variable beam radius element formulation now available in Abaqus that can be well visualized in viewer as well.

Material enhancements

• Low density foam has been introduced in Abaqus standard in 2019x FD01. This material has already been present in explicit. This material is useful in modeling highly compressible elastomeric foams.
• Output variable SROCK for rock mechanics effective stress.
• Enhancements to super-elastic materials to improve convergence and performance of material model. This application would be of interest in healthcare industry. An environment variable should be introduced to activate the model. Available from 2018x FD04.

• Transverse shear stiffness modulus has been introduced for shell and beam sections. This now obviates the user material model to deal with plates of spatially varying thickness or plates made of composites.
• Damage in concrete due to plasticity can now be modeled by defining failure criteria and element deletion criteria.
• Two new outputs introduced in explicit for cohesive elements: equivalent nominal strain NEEQ and equivalent nominal strain rare NEEQR