CAE Worldwide 2m Chapter 1: Explicit Dynamics Analysis Guide Overview Ansys Explicit Dynamics is a transient explicit dynamics system in Mechanical that can perform including the modeling of nonlinear... Ansys 11.2. Explicit Material Library - Ansys Help An extensive set of material data is provided in the Engineering Data Explicit library. This data may need to be complemented with... Ansys 6.6. User Defined Results for Explicit Dynamics Analyses - Ansys Help Erosion Status: 0 - no erosion. >0 - eroded (will not be displayed). | Type: Elemental. Effective Plastic Strain. This result is o... Ansys 8.1. When Implicit Models Can be Run in Explicit - Ansys Help Implicit methods are typically bounded by the amount of deformation and contact nonlinearity that is taking place, where Explicit ... Ansys 21.1. Autodyn Walkthrough Using Explicit Dynamics - Ansys Help Insert an Explicit Dynamics system from the Analysis Systems toolbox. * Right-click the Geometry cell (A3), and select Import a Ge... Ansys Meshing strategies for explicit simulation - CADFEM Blog Nov 8, 2024 —
Ansys Explicit Dynamics is a specialized numerical simulation tool designed to model short-duration, highly nonlinear events such as impacts, crashes, and explosions. Unlike traditional static or implicit analysis, which focuses on equilibrium, explicit dynamics uses a forward-looking mathematical approach to track the physics of an event millisecond by millisecond. Core Concept: Explicit vs. Implicit Methods The primary difference between these two methods lies in how they integrate the equations of motion over time. Explicit Method : Calculates the future state of a system based on its current known state. It uses thousands of tiny time steps (often 10-510 to the negative 5 power 10-810 to the negative 8 power seconds) but requires no complex matrix inversions, making each step computationally "cheap" and highly efficient for fast events. Implicit Method : Solves for the future state by considering both current and future conditions, requiring iterations to achieve equilibrium at every step. While it can handle larger time steps, it is computationally expensive and often struggles to converge during high-speed, chaotic events like a car crash. Key Features and Capabilities Ansys Explicit Dynamics provides several advanced solvers and features to handle extreme physics: What is Explicit Dynamics? | Ansys
1. What is Ansys Explicit Dynamics? Ansys Explicit Dynamics is a simulation solution within the Ansys Mechanical environment designed for analyzing high-speed, short-duration, and highly nonlinear events . Unlike implicit solvers (standard Ansys Mechanical), it uses an explicit time integration scheme, making it highly effective for problems where:
Inertia effects dominate (e.g., impacts, crashes, drops) Contact is complex and changes rapidly (e.g., multiple parts separating and hitting each other) Materials undergo large deformation, failure, or fragmentation (e.g., ballistic impact, metal cutting) Wave propagation matters (e.g., blast loading) ansys explicit dynamics
The solver is the same core engine as Ansys LS-DYNA (for many features), but packaged within the Ansys Mechanical UI for easier use. For advanced users, LS-DYNA still offers more material models and control features.
2. Core Theory – Why Explicit? | Feature | Implicit (Standard Mechanical) | Explicit (Explicit Dynamics) | |--------|-------------------------------|-------------------------------| | Time integration | Backward Euler (unconditionally stable, iterative) | Central difference (conditionally stable, no iterations) | | Time step | Large (milliseconds to seconds) | Very small (microseconds to nanoseconds) | | Stability | Requires matrix inversion, convergence checks | Stable if time step ≤ critical timestep (Courant condition) | | Nonlinearity cost | High per step (iterations) | Low per step (no iterations) | | Best for | Quasi-static, dynamics with slow events | High-speed impact, crash, failure | The explicit timestep is roughly: [ \Delta t \leq \frac{L_e}{c} ] where ( L_e ) is the smallest element length and ( c ) is the material sound speed. This is why mesh quality and mass scaling become critical.
3. Key Capabilities a) Material Models Includes a wide range (shared with LS-DYNA library): CAE Worldwide 2m Chapter 1: Explicit Dynamics Analysis
Elastic, elastic-plastic (Bilinear, Power Law, Johnson-Cook) Johnson-Cook for metals under high strain rate (e.g., ballistic impacts) Cowper-Symonds for strain-rate sensitive metals Drucker-Prager / Mohr-Coulomb for soils, concrete Hydrodynamic (Mie-Grüneisen, Tabulated EOS) for explosives and fluids under impact Brittle damage (e.g., glass, ceramics) Foam (low-density crushable) Composite materials (with progressive damage)
b) Contact Algorithms
Automatic surface-to-surface, single surface, tiebreak, eroding contact Eroding contact – critical for projectiles penetrating shells Spotwelds , rivets , glue (tied contacts) This data may need to be complemented with
c) Element Types
Solids (hex, tet, wedge – tet quality strongly affects timestep) Shells (for thin structures like car panels) Beams (for roll cages, frames) Discrete elements (springs, dampers, masses)