2025
This manual provides details on the features, functionality, and simulation methods available in Altair Radioss.
In this section, available explicit features for different explicit analyses are presented.
Airbags are modeled as monitored volumes /MONVOL in several different ways.
View new features for Radioss 2025.
Radioss® is a leading explicit finite element solver for crash and impact simulation.
Discover Radioss functionality with interactive tutorials.
The Radioss solver can be executed using different methods described here.
An explicit is solved by calculating results in small time increments or time steps. The size of the time step depends on many factors but is automatically calculated by Radioss.
Different material tests could result in different material mechanic character.
Composite materials consist of two or more materials combined each other. Most composites consist of two materials, binder (matrix) and reinforcement. Reinforcements come in three forms, particulate, discontinuous fiber, and continuous fiber.
In Radioss, a kinematic condition is a nodal constraint applied to a set of nodes.
Several interfaces are available in Radioss, this section deals with contact interfaces only. Each interface is distinguished with a type number.
A monitored volume is defined with one or more shell (3-node or 4-node) parts.
An "AIRBAG1" time step is estimated into the Engine, but this time step will never control the time step during the run. If that is the case, it means there is a non-physical airbag definition in the input deck.
Present guidelines define modeling and validation requirements for numerical airbag models in Radioss with Finite Volume Method (FVM).
Airbag numerical models are created for the numerical simulation of crash events related to occupant safety problems. Airbag models may differ in the amount of detail and accuracy depending on their intended application.
Reference geometry should be represented as flat node based (/XREF) or element based (/EREF) geometry.
The gas generator model should represent all details available in CAD data: gas generator, injector openings, and retainers.
Material for the air inside of the airbag should be specified either through /MAT/GAS/MASS, /MAT/GAS/MOLE or /MAT/GAS/PREDEF.
The nonlinear anisotropic material LAW58 used be used as the airbag material.
In Radioss the standard method for airbag calculation is the Finite Volume Method (FVM).
Each vent hole should be represented as a separate component in the same position as in the CAD geometry.
Porosity of airbag material is modeled by the addition of a porosity card /LEAK/MAT to /MAT/LAW58 card.
External and internal airbag components including inter-chamber voids and void components used for vents should not have any geometrical intersections.
The airbag housing should represent all details available in CAD data.
A folded airbag model with the correct material, property, contact definition, and specified reference geometry should not move before activation of injector.
A uniform pressure run should be performed to make sure that gas dynamic data, injector input, fabric materials, and contacts give physical results.
By using data from a tank test output, it is possible to obtain the temperature and the mass flow of the gas supplied, which can be used as input to Radioss.
The objective here is to provide some guidelines on how to troubleshoot a simulation where the airbag does not deploy properly or crashes because of the airbag.
In this section, fluid and fluid-structure simulation is presented.
The Smooth Particle Hydrodynamics method formulation is used to solve the equations of mechanics, when particles are free from a meshing grid.
The objective of the Multi-Domain technique (also referred to as RAD2RAD) is to optimize the computing performances of large scale Radioss models.
This section is comprised of error messages in ascending numerical order.
This section is comprised of warning messages in ascending numerical order.
This manual provides a detailed list of all the input keywords and options available in Radioss.
This manual presents examples solved using Radioss with regard to common problem types.
This manual presents solved verification models.
This section provides quick responses to typical and frequently asked questions regarding Radioss.
This manual provides detailed information about the theory used in the Altair Radioss Solver.
This manual describes the interface between Altair Radioss and user subroutines.
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