Discussion of Time-Step Size - Lesson 3

This video lesson shows that explicit time integration works best for fast events like a car crash or a bullet impact that occur in the range of milliseconds to seconds. The implicit method works better for slower events like material creep or gear intermeshing, which can take place in the range of minutes to days. In general, the time-step size is limited so that a stress wave cannot travel farther than the smallest element characteristic length in a single time-step. This lesson is part of the Ansys Innovation Course: Time Integration. To access this and all of our free, online courses - featuring additional videos, quizzes and handouts - visit Ansys Innovation Courses at www.ansys.com/....

[@AnsysLearning]

This video is part of the free Ansys Innovation Course “Time Integration”. Access all of the course contents including additional lessons, handouts, simulation examples with starting files, homework problems, and quizzes: courses.ansys.com/index.php/courses/time_integration/
Check out other courses on the website while you’re there. Happy learning!”

[@krishkrishna7481]

I see no reason why a background music was added to this video.

[@KshitijGuptaisbatman]

best video ever. !!

[@jawaharfathima]

The implicit method is not unconditionally stable for all nonlinear equations. The restrictions in the time step may arise from the nonlinear term in the equation.

[@AnsysLearning]

Thanks for watching & providing feedback! Visit Ansys Innovation Courses for free courses, including videos, handouts, simulation examples with starting files, homework problems, and quizzes here: ansys.com/courses.

[@yonastadesse3749]

nice presentation

[@sandeepsane8529]

what are the constraints have you taken for required ansys time as 2 seconds

[@s4shridhar]

This video is very useful! I have a doubt which may be silly...for calculating the value of c which is m/s, the units of Elastic modulus and density don't have a time unit then is the formula missing some constant ?

[@AnsysLearning]

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[@chrisie1997]

Elastic modulus is Newton/length^2.
Newton is mass*length/time^2 so there actually is a time unit in the formula.

[@riykiapriandi1304]

So, number of cycle in ansys explicit simulation need to calculate first?

[@AnsysLearning]

Thanks for watching! Please post your query on the Ansys Learning Forum for a detailed answer from the wider Ansys Community: ansys.com/forum.

[@fluidos971]

i know there is adjustable time step size option for volume of fluid (VOF) method, but i want to know is there any adjustable time step size option in general ?

[@zaidhadi854]

how to calculate the time-step if there is more than one material in the model? e.g. plate consists of aluminum and steel.

[@AnsysLearning]

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[@jeophilip4353]

min time step out of the two material is considered

[@zaidhadi854]

@@jeophilip4353 Thanks!

[@aliikhalil9263]

what's the meaning of element ? is that the particle for instance?

[@AnsysLearning]

Thanks for watching! Please visit the Ansys Learning Forum (www.ansys.com/forum) for an answer to your question.

[@michael.adel.shafik]

@@AnsysLearning it is not working :/

[@jeophilip4353]

structure is divided into small parts called elements ('E' in FEA)

[@Evanyali]

for example, if we split a beam into 'n' elements, then the beam will have 'n' elements and 'n+1' nodes. elements are the basic component how FEA software calculates stress and strain.