#### Which of the Explicit or Standard solvers is more suitable for my problem?

Abaqus/Standard is a good choice to solve static, low-speed dynamic, steady-state transport, or smooth nonlinear analyses. On the other hand, Abaqus/Explicit is the clear choice for quasi-static events such as the rolling of hot metal, severely nonlinear behavior such as contact, transient response, or high-speed dynamic analyses such as crash analysis or drop test. There are, however, certain problems that can be simulated well with either program.

#### What are the main differences between Explicit and Implicit Solvers in Abaqus?

- Implicit is unconditionally stable.
- Implicit schema is incremental as well as iterative. However, the explicit schema is only incremental.
- In terms of cost per increment, it is costly for implicit and cheaper for explicit.
- Disk space and memory usage are typically much smaller than that implicit: look at this diagram.

#### What is the difference between the solving strategy of Abaqus/Standard and Abaqus/Explicit?

These solvers are based on two approaches in FEM analysis, namely implicit (for Abaqus/Standard) and explicit. The distinction between the two different numerical approaches makes it possible to understand which solver to use. Abaqus/Standard must iterate to determine the solution to a nonlinear problem, but Abaqus/Explicit determines the solution without iterating by explicitly advancing the kinematic state from the previous increment.

#### What methods are used to analyze problems in Implicit and Explicit Solver?

In the case of the implicit method, equilibrium is enforced between externally applied load and internally generated reaction forces at every solution step (Newton Raphson method).

In the case of the explicit method, there is no enforcement of equilibrium. But this does not mean that explicit is not accurate. You can minimize its deviation from equilibrium to almost zero by increasing the number of solution steps, i.e. reducing the time step size.

#### How can we solve problems that involve several analysis stages?

Abaqus provides a useful capability for simulations involving several analysis stages. In this ability, the user can start a simulation in Abaqus/Explicit. Then the results at any point within the solver run can be transferred as the starting point for continuation in Abaqus/Standard. The user will define new model information during the import analysis.

## Abaqus Explicit or Abaqus Standard?

Generally, if we put aside CFD solver (**Abaqus/CFD**) that is used for fluid problems, the heart of Abaqus is the analysis modules, **Abaqus /Standard** and **Abaqus /Explicit**.

## Explicit And Implicit Solvers in Abaqus

These solvers are based on two approaches in FEM analysis, namely **implicit** (for Abaqus/Standard) and **explicit**. The distinction between the two different numerical approaches, makes it possible to understand which solver to use.

In the case of the implicit method, equilibrium is enforced between externally applied load and internally generated reaction forces at every solution step (**Newton Raphson** method).

In the case of the explicit method, there is no enforcement of equilibrium. But this does not mean that explicit is not accurate. You can minimize its deviation from equilibrium to almost zero by increasing the number of solution steps, i.e. reducing the time step size.

We can list the main differences below:

Implicit is unconditionally stable.

**Implicit** schema is *incremental* as well as *iterative*. However, **explicit** schema is only *incremental*.

In terms of cost per Increment, it is costly for implicit and cheaper for explicit. Disk space and memory usage are typically much smaller than that for implicit. The explicit method shows great cost savings over the implicit method as the model size increases:

Therefore, **Abaqus/Standard** must iterate to determine the solution to a nonlinear problem but **Abaqus/Explicit** determines the solution without iterating by *explicitly* advancing the kinematic state from the previous increment.

## Explicit or Standard, Which one I use?

For many analyses, it is clear whether Abaqus/Standard or Abaqus/Explicit should be used. For example, Abaqus/Standard is more efficient for solving smooth nonlinear problems; on the other hand, Abaqus/Explicit is the clear choice for high-speed dynamic analyses such as crash analysis or drop test. There are, however, certain problems that can be simulated well with either program.

Typically, these are problems that usually Abaqus/Standard can solve but may have difficulty converging because of contact or material complexities, resulting in a large number of iterations. For example, in problems where very complex contact conditions or very large deformations are present. Such analyses are expensive in Abaqus/Standard because each iteration requires solving a large set of linear equations.

In the below video, see the complete comparison between Abaqus standard solver and the explicit solver:

It would be useful to see **Abaqus Documentation** to understand how it would be hard to start an Abaqus simulation without any **Abaqus tutorial**.

Good write-up. I definitely appreciate this site. Keep it up! Elle Tanny Kirtley

Hello, thank you for this article. I needed to choose one of these two solver to solve my problem. This article helped me choose the most suitable solver. thank you