Time Step in Explicit Dynamics - Lesson 2

Unlike implicit methods, explicit time integration methods are conditionally stable, meaning that they are stable only when the time step size is less than a certain limit. In this video, we learn how to calculate this upper limit or the critical time step. We then talk about the ways in which the mesh and the material properties influence the critical time-step. Finally, we discuss ways to manage the critical time step by either manipulating the mesh to ensure that no small elements drive the critical time step size down or by using mass scaling that selectively modifies the density to increase the critical time step size.
00:00 - Intro
00:49 - Conditional stability of explicit analysis
02:06 - Critical time step and CFL condition
02:55 - Characteristic length of an element
04:05 - Dependence of critical time step on material properties
05:46 - Increasing critical time step by modifying the characteristic length
07:15 - Mass scaling
08:05 - Checks associated with mass scaling
09:09 - Example demonstrating mass scaling
10:35 - Summary
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[@muhammadtayyab6280]

Awesome video 👍🏻
Took me a lot of time....like a lot... to learn all of these parameters effecting computational time and accuracy of an explicit dynamic simulation by myself.

[@AnsysLearning]

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[@sachinpande8324]

Nicely explained. Thank you so much!

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[@alokkumarnyati]

Excellent explanation 👏

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[@abdallahyounoussi9954]

Thank you very good explanation😮

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[@mianimran5985]

Nice explanation. How to find the critical time step for geometry in lsdyna?

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[@behnammashhadi7022]

Thank you for the video. How did you plot the CFL?

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[@riccardop2219]

Is the “time step size”equal to the “end time”?

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