Variation in Simulation results and experimental results

Hi,

Can you share the .hm or .rad files for this .(version 13)?

Dear Gopal,

 

Please find the attached hm file.

 

Thanks

RAM

Unable to find an attachment - read this blog

Dear Gopal,

 

Please check the model attached in previous post and let me know the errors 

 

Thanks

RAM

Hi,

I was going through the model and following issues are noticed.

1) Penetration and intersection needs to be cleared.

2) Quality of mesh needs to be reviewed . Warpage <15, skew<40, jacobian>0.6, min. length now is 2.15 can be increased for better time step etc.

 

Is the material property entered is test data ?

Also I think you have not taken the output for the reaction force Vs  displacement. This can be done by making the RBODY for both upper and lower actuators and then requesting output blocks for it , so that you can compare the same with experimental data.

 

Also model washers at the mounting locations as maintained in physical testing.

Have you also tried with imposed displacement/velocity as load instead of force?

 

Dear Gopal,

 

I had one doubt, for this type of analysis what type of material properties should be used?

 

Data available for steel tube (CR)

 

Yield stress ,Min =180Mpa

                    Max= 240 Mpa

 

Tensile stress ,Min =310Mpa

                       Max= 370Mpa

 

Which value should be used Min or Max??

 

Thanks

RAM

Hi,

This is a range of values and generally for co-relation we need actual material properties (by test data) and it is more important here as it is case of plasticity. If not available, you need to alter the values in the above range and see whether it is co-relating with testing or not. 

Dear Gopal,

 

Had the test report of the steel tube in which they mentioned only the minimum values of yield and ultimate tensile strength.

 

Can we use that values?

 

Thanks

RAM

 

 

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Dear Gopal,

 

Had the test report of the steel tube in which they mentioned only the minimum values of yield and ultimate tensile strength.

 

Can we use that values?

 

Thanks

RAM

 

 

Dear Gopal,

 

Had the test report of the steel tube in which they mentioned only the minimum values of yield and ultimate tensile strength.

 

Can we use that values?

 

Thanks

RAM

 

 

Dear Gopal,

 

I came to know that physical testing of seats is done for 55 sec.

 

Ramp time achieve the max load is 25 sec 

 

Once the max load is achieved the load is maintained constant for 30 sec.

 

How it can be simulated with less solving time???

 

Thanks

RAM 

Hi,

I think this can be done with non-linear quasi-static analysis type in optistruct where the time is not a factor and solver will maintain the load ramping so that equilibrium condition is defined at every interval.

Dear Gopal,

 

In this journal they co-related the results for H1H2 test

 

http://www.ierjournal.org/pgcon/434.Performance Enhancement of School Bus Seat as per AIS-023 through FEA and Validation.pdf

 

 

Dear Gopal,

 

Please give the guidelines for the  non-linear quasi-static analysis .

 

How to give boundary conditions and loads ??

 

If any tutorial available please share .....

 

Thanks

RAM

Hi Ram,

Even though this kind of analysis seems to be a quasi static problem it involves strong contacts and chances of local buckling. And I think It's quite difficult to converge in implicit. 

But give a try.

Meanwhile please see a research paper in this link where a similar analysis was done: https://edupediapublications.org/journals/index.php/IJR/article/download/3096/2973