Quasi Static Analysis in Abaqus/FEA, Part - 02 Mass scaling

[@topian789]

So I have reached the end of your beautifully explained series of videos on "Dynamic Analysis using Abaqus". Thanks a lot sir 👍 I really appreciate your input and engagement to explain the not very easy topics in the fields of CAE.

[@simtech0598]

Always welcome dear, There are lots of to share but due to restricted time I'm unable to upload more vidy.

[@lokeshs3324]

I really happy watching your video. It is nice and gives me better understanding of concepts in Abaqus. Thanks for your content great work

[@simtech0598]

Dear, I suggest you to go with part-1 also.

[@lokeshs3324]

@@simtech0598 am trying to start watching all your video from a year back. So definitely I'll watch them in proper sequence for sure 😊 Is there any way that I could contact you to clarify my queries immediately.. when it comes to Abaqus and HM..

[@simtech0598]

Dear, You can mail me and msg me. My contact details is in video discription.

[@ivshabaldin]

But when scaling the mass, the wave speed also decreases and there may be errors due to its excess? And isn’t it more profitable from the point of view of computational time to shorten the loading period, since in this case the inertial forces are proportional to the first degree of this reduction, and when scaling the mass it is necessary to increase the inertial forces in proportion to the square of the increase in the stable increment?

[@theluis469]

How should I validate mass scaling in a dynamic explicit problem? I'm analyzing a machining procedure, and the speed of the tool is considerable, how can I see if the analysis is acceptable by looking at the energies? Thank you so much for your videos!

[@simtech0598]

Dear, Effect of Mass scaling can be checked by kinetic energy with respect to internal energy of system. As i explained in video.

[@mohdsuhairilmeon6117]

Hi..very informative video. How to know the right factor?..e.g 16, 24, 32...100....?or we can simply try the factor with any numbers and later on once completed, verify with energy?

[@simtech0598]

Yes, Better to use scale factor and check energy plot.

[@xintong3168]

Good video. I have a question, if I want to scale down the mass, how can I do? Change directly the property of the material? or other ways? Thanks in advance.

[@sanjaySanjay-gz7wm]

Good content

[@lokeswarimalepati867]

Sir Can you please explain how to define amplitude for different loading histories For ex: cycling loading

[@simtech0598]

Dear, already 2 videos uploaded for amplitude in Abaqus. Go through channel videos.

[@HJ-xr3wq]

Hi sir, by defining mass scaling in Explicit step Abaqus will consider quasi static analysis automatically? or we should tell Abaqus somewhere that you must use quasi static analysis?

[@simtech0598]

Dear, Please watch all videos of 'dynamic analysis with Abaqus' playlist carefully. When the system is sufficient slow...we can artificially make it faster by applying mass scale technique...so if problem is already in dynamic condition...we cannot apply mass scaling.

[@meetpatel-kt8cv]

Sir, I am having cyclic load ( 135 seconds) and I am performing quassi static analysis with mass scalling. To use time scaling, what changes in 'Time period' Value and 'amplitude' is required?? Let us say if I am reducing it to 13.5 second, should I keep time period and amplitude time 135 as it is or 13.5 second?

[@simtech0598]

Time period and amplitude both for 13.5 sec.

[@samarthacharya5180]

Can i say that the results of my simulation using mass scaling are accurate if the kinetic energy of the system remains less than 1% of the Internal Energy? is there any such parameter that can quickly help me determine whether my simulation is acceptable or not?

[@simtech0598]

Yes, 1% KE is less enough to ignore.. compare to IE. However, results may wrong due to some other reason. ENERGY itself a parameter to judge whether simulation is correct or not.

[@samarthacharya5180]

@@simtech0598 thank you so much, this tutorial helped me a lot!

[@kothilngammaring718]

Hi @Simtech05, I have been watching this video again and again with the Part-01 video. I have been thinking and try to express myself that if the inertia effect in the simulation system is neglected(insignificant) by introducing mass scaling & load increment method, the system kinetic energy is still not zero (sometimes very small and big depending on the accuracy of the analysis). Where is this ALLKE kinetic energy comes from? How can I explain that if the ALLKE is high, why is it high and what makes it high? Is it coming from the crushing tube by releasing/converting the strain energy as KE? Thank you!

[@simtech0598]

Dear, You misunderstood the concept. 1. Inertia effect is negligible than only we can utilise quasi static concept (mass scaling and increase load rate techniques).. Not that - inertia effect neglected by mass scaling or increase load rate. 2. The value of KE depends on mass scaling that you used or increased load rate that you defined. Ideally for Quasi-static simulation KE of system at each point is zero. But if someone use huge mass scaling of very fast load rate (short time event) then KE increase and mislead results. 3. KE is not coming form any other energy. Its from momentum of system. Think about this point - KE = 1/2mv^2 If v is very small KE is zero.. We can take advantage of it...even if we increase mass up to certain limit still KE will be approx zero bcz v is very small...and square of v further decrease value.

[@kothilngammaring718]

@@simtech0598 Thank you for your response. You are right, inertia is negligible but not neglected. 2. I believe when we talk about this ALLKE, its the KE of the deformable part only. We always check the KE and compare with IE even in purely explicit dynamics as well as in quasi-static analysis as you have mentioned. We then conclude that the analysis result is acceptable based on the energy plot comparison. I can understand now that the KE in quasi-static analysis can be increased depending on the mass scaling value. How can I express the cause of the high KE plot in pure explicit dynamic analysis? Is it because purely due to the unrealistic relation between the applied load and the time period event? 3. I believe when you say velocity is very small means that v can be made very small by making the inertia negligible.

[@simtech0598]

1. Inertia is negligible and neglected. 2. How can I express the cause of the high KE plot in the pure explicit dynamic analysis? - The cause may be a variable load with high frequency, maybe high inertia, impact, acc..etc. Is it because purely due to the unrealistic relation between the applied load and the time period event? - There is no unrealistic relationship. I don't know what you want to ask? 3. You are not understanding the point - we are not making v negligible by ignoring inertia. V is zero, system is in equilibrium for each increment, that's y we can assume inertia negligible. We are not making KE zero...KE is zero that's why we can use this quasi-static approach. Listen starting of the video carefully.

[@chetanshenoy941]

Hello. Your videos are really helpful.. I have one question.. how to decide the time period for front bumper assembly using dynamic implicit analysis in abaqus standard for Quasi static application.

[@simtech0598]

Dear, For implicit - Quasi static technique you can use natural time period. You need to worry about time period only in explicit step.

[@chetanshenoy941]

@@simtech0598 Thanks for the reply.. is it necessary to use time period value as natural time period or I can use time period value as 1.

[@simtech0598]

Use natural time period.

[@Jootawallah]

@@simtech0598 I am sorry, how does one calculate the natural time period for a system?

[@simtech0598]

Perform frequency analysis for the model/assembly.

[@agunglaksono3852]

Thankss

[@zhaojianfeng3531]

why this is called Quasi Static Analysis? as we can see it is a explicit analysis

[@simtech0598]

Dear, Please go through part-1 also. Offcourse we are using explicit step but to solve static problem. I highly recommend you to go through 1st video of playlist.

[@syakiraliff]

can you do a fretting wear simulation on coating sir?

[@simtech0598]

Dear, I make videos on FE concepts...not on special component. However, if you have any specific question in your simulation..you can ask.