Solvers for every situation

LINEAR SOVERS IN ABAQUS / QUICK ANSWERS FOR EARLY DECISION MAKING

When working in the linear solver domain, we are typically not interested in contact, large deflectionss, and laterial behavior after yield. We can then use linear solvers to get extremely fast initial results.

In Abaques, these linear scenarios are called Linear perturabation analyses, and they can take into account the state of the model after prior nonlinear analysis. For exemple =, an accurate frequency extraction can be conducted on an inflated and rolling car tire. Linear sovers provide a foundation for engineering analysis tools by deliverinng efficient solutions to questions regarding load capacity and stiffness. These tools are often utilized as a starting point for more advanced analyses such as NVH (noise, vibration, and hardhness) and durability analyses.

A Abaqus contains useful procedures that are not available in SOLIDEWORKS Simulation, such as complex eigenvalue extraction, subspace-base steady state dynamic, and direcr solution steady state dynamic. Complex eigenvalue extraction provides solutions to extract (as the name implies) the complex component of eigenvalue problems. This technique is popular for solving brake squeals and other acoustic-related problems. Steady-state dynamic analyses provide the steady-state amplitude and phase of the response of a system dur to harmonic excitation at a given frequency. The steady-state dynamic results generated in Abaqus can be utilized for subsquent fatique or acoustic analyses.

When comparing software tools, it is important to understand that these tools can provide different underlying technoologies to specific solver procedures. For example, in abaqus, there are multiple ways to conduct naturak frequency extraction. Each of these methods are designed for specific situations.

FREQUENCY EXTRACTION PROCEDURE TYPES

Lanzcos is the default solver witrh the most general capabilities. This method is used by the SOLDWORKS Simulation frequency solver when the "FFEPlus" solveer is selected. This is considered the slowest of the available frequency extraction methods.

Automatic multilevel sebstràucturing (AMS) is the increased speed for complex models with many eigenmodes requested. incredible performance has been achieved with GPU acceleration using this technique.

Subspace interation is the increased speed for models with a low number oiif eigenmodes requested (less than 20). Used by SOLDWORKS Simulmation frequency solver when the direct space solver is selected.

NONLINEAR IMPLICIT SOLVERS IN ABAQUS : ACCURATELY PREDICTING COMPEXITY

Veenturing outside of the linear static and dynamic domain are solutions that can capture complex nonlinearities sush ch as contact, large deformations, and materials (hyperelasticity, viscoelasticity, plasticity, etc.). These solutions are available in either the implicit or explicit domain and can solve both static and dynamic nonlindear problems.

Implicit and explicit methods are used to solve partial differential equations that represent system of complex physics such as a structure's deflection under load. The primary difference vetween the two methods is that the implicit method requires an additional calculation that solves for equilibriul. This satisfaction of equilivrium allows for a much lower number of increments to solve the problem while maintaining the nonlineariteies, however , non-convergence difficulties are possible.

One additional benefit of abaqus implicit methods is that they can benefit from GPU acceleration. This can provide valiable perfermance increases in Abaqus solving at a very low additional licensing cost.

Abaqus and SOLIDWORKS Simulation both have static, dynamic, and heat transfer capabilities in the implicit solution procedures. However, Abaqus has additional capabilities related to static ricks, basic electromagnetics, soils, pore fluid flow, and fully coupled physics. these solvers allow engineers to take a deeper dive into more complex physics that their products may be experiencing. For example, static riks allows you to see the post-buckling behavior to further understand the structural response after the bifurcation point. This would not be possible in a traditional implicit sulution procedure.

Static Implicit (Left) vs Static Riks (Right)

While abaqus and SOLIDWORKS Simulation both have an implicit static solver, thaydo have differences that affect accuracy, convergence, and speed. For example, the developers of Abaqus have put extensive capabilities into efficiently simulating large deformation and contact interactions of nonliear materials.

Bumper crush in SOLIDWORKS Simulation

Bumper crush in Abaqus

Solution : SOLIDWORKS Simulation 

Time: 6 hours, 25 minutes 

Completed : 76%

DYNAMIC EXPLICIT SOLVER IN ABAQUS : WHEN THINGS GET CHAOTIC

The explicit method is utized for highly nonlinear physics where the implicit method would struggle to solve due to convergence issues. Due to not having the equilibrium check that the implicit method has, there are typically many more increments required to solve the problem of interest. This key feature allows users to taskle extremely nonliear events such as forming, impact, failure, and strain-softening plasticity to name a few. The explicit solver is also very efficient at parallelization of the problem, meaning the solver is also very efficient at paralleliztion of the problem, meaning the solver scales very well with addional computing resources.

NONLINEAR/EXPLICIT TECHNIQUES

Abaqus/Explicit is a fundamental technology relied on by a variety of industries seeking to understand transient, high-energy, and large deformation scenarios. This solver is also an extremely useful tool for quasi-static analyses of long-duration/displacement events that would be difficult to converge using an implicit solver. In addition to this important solver technique, can easily import results back and forth between the implicit and explicit codes. This allows simulation physics that are better suited foioir the implicit solver, for example, bilt pre-tensioning before a crash event that requires the explicit solver.

Another example would be soolving a forming event in the explicit solver and then importing it into the implicit static solver to calculate the part spring back =. SOLIDWORKS Simulation does have an explicit solver under the hood for the drop test study type, but it is limeted to only droop style impact scenatios of simple assemblies and select material properties. Crasges and other impacts are nor possible.

HOW MUCH CONTROL DO YOU HAVE ?

When considering the different solution techniques available, you should also consider differing levels of engagement with the actual solver. Abaqus can provide inputs in the form of subroutines, modifying the solution controls, and applying different types of damping to, when used correctly, more easily solve complicated convergence situations. While SOLIDWORKS doer include access to some of these advanced controls, they are limited in scope. Furthermore, the ability to add subroutines to the SOLIDWORKS Simulation solvers is not possible.

Note. Abaqus specializes in more robust and efficient solver techniques that allow for the most accurate and efficient solutions, and the most advanced physics. When purcharsing an analysis tool, you may want to consider your shoprt-and long-term analysis goals. As you expand your analysis capabilities, abaqus is there to grow with you.