What is Explicit Dynamics?

It happens to everyone. You reach to answer your phone, grab it wrong, and suddenly it’s falling — kerplunk! — onto the hard floor. For engineers, knowing how their products will stand up in scenarios like free falls is critical to achieving their safety and performance goals. To test their designs in these highly nonlinear, high-speed situations, they rely on a simulation methodology called explicit dynamics analysis.

Explicit dynamics is a time integration method used to perform dynamic simulations when speed is important. Explicit dynamics account for quickly changing conditions or discontinuous events, such as free falls, high-speed impacts, and applied loads. Because these “nonlinear dynamics” are integrated into the simulation, explicit dynamics is the preferred choice for simulating highly transient physical phenomena.

Explicit Dynamics Capabilities

Explicit dynamics tools help engineers to explore a wide range of challenges:

• Short-duration, complex or changing-body interactions (contact)
• Quasi-static loads (low strain rates)
• High-speed and hypervelocity impacts
• Severe loadings resulting in large material deformation
• Material failure
• Material fragmentation
• Penetration mechanics
• Space debris impact (hypervelocity)
• Sports equipment design
• Manufacturing processes with nonlinear plastic response
• Drop-test simulation
• Explosive loading
• Explosive forming
• Blast-structure interactions

Figure 1. Ansys explicit dynamics tools help users meet solution requirements of various complexities based on problem details and user expertise.

What is Explicit Dynamics at Ansys?

If your product needs to survive impacts or short-duration, high-pressure loadings, you can improve its design with Ansys explicit dynamics solutions. Specialized problems require advanced analysis tools to accurately predict the effect of design considerations on product or process behavior. Gaining insight into such a complex reality is especially important when it is too expensive — or impossible — to perform physical testing.

The Ansys explicit dynamics suite enables you to capture the physics of short-duration events for products that undergo highly nonlinear, transient dynamic forces. Our specialized, accurate, and easy-to-use explicit dynamics tools have been designed to maximize user productivity.

With Ansys, engineers can gain insight into how a structure responds when subjected to severe loadings. Algorithms based on first principles accurately predict complex responses, such as large material deformations and failure, interactions between bodies, and fluids with rapidly deforming structures. Highly complex problems, especially ones with high strain rates and other phenomena that are difficult to converge with general-purpose implicit solution methods, can be resolved using sophisticated, state-of-the-art mathematical algorithms.

Defaults are safe and reasonable for most common problems, which means that you spend less time setting up and running problems and more time optimizing products for performance, durability, and cost, and removing design flaws.

In many cases, the accuracy of an explicit solution can be verified only through comparison with physical experiments. For some problems (such as explosions), it may be too expensive or even impossible to perform physical tests. Despite this, Ansys users around the world rely on the precision of our explicit simulation results.

Implicit vs. Explicit Analysis

While both implicit and explicit methods are used to solve time-dependent simulations, deciding which one to use depends on the problem being solved.

Use implicit dynamics when solving for dynamic finite element analysis (FEA)  problems that involve mild nonlinearity and when large timesteps can be used. This includes:

• Static equilibriums.
• Slow, linear, and mildly nonlinear processes.
• Large time increments.

Use explicit dynamics when calculating highly complex and nonlinear problems involving rapid changes such as deformation or failure of material, such as:

• Drop tests.
• Impact and penetration.
• Breakage.
• Shock waves.
• Large deformations.

Which Explicit Dynamics Tool is Right for You?

Ansys LS-DYNA

Ansys LS-DYNA is the most frequently used explicit simulation program in the world, capable of simulating applications like drop tests, impact and penetration, smashes and crashes, occupant safety, and more.

Ansys Explict Dynamics within Ansys Mechanical

Ansys Mechanical is the best-in-class finite element solver offering structural, thermal, acoustics, transient, and nonlinear capabilities to solve your most complex structural engineering problems.

Ansys Autodyn

Ansys Autodyn offers a range of models to represent complex physical phenomena such as the interaction of liquids, solids and gases; the phase transitions of materials; the propagation of shock waves; and even explosions.

For solving highly transient, highly nonlinear simulations, explicit dynamics is the preferred choice of time integration methods. To learn about the industry’s leading explicit simulation software, check out the Ansys LS-DYNA Multiphysics Solver.