This is a relatively bigger blog compared to previous ones because of an obvious reason; it covers a broad spectrum of non-linear enhancements which is Abaqus core technology. The blog covers four sections: additive manufacturing, element technology, material enhancements and fracture mechanics along with few other minor enhancements
- Pattern based thermo-mechanical analysis: While in many cases laser scan paths are available to simulation users it is not always true. For those situations in which machine users do not wish to share their machine IP’s, a pattern based approach has been introduced which uses a raster scan path instead of a trajectory scan path. Material orientation and Anisotropic behavior are supported but not suitable for detailed microstructure simulation. This application is different from eigen strain simulation.
- Event series enhancement: 2GB data size limit of event series was removed in 2019xGA and now event series can include up-to 420 million events.
- Free surface evolution enhancements: In case of tie constraints, algorithm has been enhanced to include ties that are not activated until the underlying element becomes active.
- Output enhancements: MAXPSCRT has been introduced to include maximum principal stress crack initiation criterion. It is available for both field and history outputs. BLADEINTERFERER has been introduced to predict clash between recoater and printed part. This will be available in 2020xFD01.
- Shear panel element update: SHEAR4 was introduced in 209xFD01 to model thin reinforced plates. It supports buckling. Equivalent shear flow output called SQEQ is supported.
- Pyramid heat transfer element: DC3D5 has been introduced to manage transition between tetrahedral and hexahedral elements in thermal analysis.
- Fluid pipe element enhancements: These elements now support following Non Newtonian flows as well:
- VUMAT enhancement: A parameter has been added to define alternate bulk and shear modulus that can be used by explicit to find suitable time increment. It is called EFFMOD and visible in viewer. Abaqus CAE support is available from 2020xFD01.
- Kinematic hardening enhancement: The material model has been enhanced to model stress relaxation behavior for metals subjected to step strain input. Suitable for metals that show viscoelastic like behavior during step inputs.
Creep Laws enhancement: Current creep models have A with dimensionality that creates ambiguity. The strain and time laws have been enhanced as follows to make A dimensionless. These enhancements are applicable to all the creep models.
Viscoelastic material enhancement: The prony series has now been enhanced to include frequency domain as well. Earlier prony series was valid in time domain only.
Yield surface enhancement: The non quadratic yield surface has been introduced in 2019xFD04. It is referred to as Barlat Plasticity. The stress component requires 18 coefficients and 1 exponent.
- Metallurgical phase enhancement: In prior releases, the effect of additive manufacturing and other heat treatment processes on material properties at microstructural level required USDFLD subroutine. Effective 2020xFD01, this routine has been included on the material definition itself. Inservice performance of printed parts can now be more accurately simulated.
- 3DX injection molding compatibility: The fiber orientation and residual stresses from third party simulation such as Moldflow can now be converted to a SIM file format. That means the 3DX structural simulation apps can now read moldflow results to predict in-service loads and warpage from third party plastic injection results.
- Non linear enhancement: In earlier releases, the direction of pre-tension section normal was not updated even in general step. Effective 2020xGA, the cut section normal direction can be updated in large displacement or large rotation analysis. It is activated as follows in the input file
*PRE-TENSION SECTION, FOLLOWER = (YES/NO)
Fracture Mechanics enhancements
- Linear elastic fatigue enhancements: Linear elastic fatigue crack model was introduced recently in collaboration with NASA ACC team to model crack propagation for cyclic fatigue cycles. It allows for change in contact conditions as well as non-linear geometry effects. Several enhancements have been made in this model in recent FD’s. In 2019x FD03, an alternative method to smoothening of crack front was introduced. In 2019x FD04, mode dependent stiffness degradation was introduced.
- Cohesive elements for Multiphysics: Couples temperature-displacement cohesive elements have been introduced to simulate debonding due to thermal expansion as well as hydraulic fracture. These elements are COH2D4T, COHAX4T, COH3D6T, COH3D8T. Coupled temperature-displacement-pore pressure elements available as well to include gap conductance effect. There is no change in the structural response of these elements.
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