This year 2019 Abaqus release has seen number of potential enhancements in Abaqus explicit. Some are general purpose while others are tied to specific procedure and application. Let’s have a look at what’s new in the explicit basket.

• Lumped Kinetic Molecular model: This model has been developed to simulate behavior of gases that can be of much use in air bag deployment simulation. The method is based on kinetic theory of gases which states that pressure exerted by a gas in closed chamber is a result of collisions between gas molecules as well as between gas and chamber surface. These collisions are perfectly elastic in nature. As number of molecules in a mole of gas is equal to Avogadro number (6.023e23) which is very large from computational perspective, lumped mass approach is used in Abaqus in which a gas particle is defined as a collection of many molecules. The method has been validated with analytical approaches. This method now replaces the Unified Pressure Method that cannot capture the change in pressure as the airbag expands. However, LKM is computationally more expensive than UPM. Best approach might be to use LKM during airbag expansion when pressure variation is large and then switch to UPM method. Switching time should be defined in such a case. Most expensive method is still CEL.

• C3D10 element has been introduced in explicit that is a true second order element that offers larger stable time increment compared to C3D10M or linear element. It supports all the loads and BC’s supported by conventional continuum elements in explicit.
• Limiting stop feature: It is not possible to stop the explicit analysis when a certain output parameter reaches a limiting value. These physical parameters may be node based such as reaction forces or element based such as equivalent plastic strains. The keyword is *FILTER.
• Improved performance: Substantial decrease in solver time when performing large system level crash simulation over high performance cluster. Below is the example of a 5M DOF crash model on multiple cores.

This blog is a part of series “what’s new in SIMULIA 2019”. Please follow our blog site regularly for next blog article on this topic.