what is the difference between drop test and shock test?

Mintu

Currently iam working on drop test analysis for electronic unit.can any body explain what is the relation between drop test and shock impulse ? when should we have to perform drop test and shock test analysis?

PaulAltair

What graph files do you need?

The T01 file output (graph data) frequency is set by the /TFILE card in your engine (0001.rad)

The T01 file from your run can be read into hypergraph to plot energies from the model (in the T01 by default), if you need extra data (for example specific time histories for entities in the model) then you need to request those with /TH cards in the run

If you see the replies above, it is shown how to plot the energies

PaulAltair

I'm not an expert in electronics test, but I would interpret the difference in definition as being whether you take into consideration the local effect of the impact itself. i.e. a shock test may just be an impulse on your model, applied on the whole structure (such as might apply to a device mounted in a vehicle or contained in packaging, or even just the shocks that maybe experienced by a phone while it's user is jogging), whereas a drop test is replicating an impact (contact with ground other object). So, a drop test will result in a shock (e.g. the corner of your phone hits the ground, the remainder of the phone experiences shock even if it doesn't contact the ground), but a shock test is not always necessarily an impact.

Mintu

Paul Sharp_21301 said:

I'm not an expert in electronics test, but I would interpret the difference in definition as being whether you take into consideration the local effect of the impact itself. i.e. a shock test may just be an impulse on your model, applied on the whole structure (such as might apply to a device mounted in a vehicle or contained in packaging, or even just the shocks that maybe experienced by a phone while it's user is jogging), whereas a drop test is replicating an impact (contact with ground other object). So, a drop test will result in a shock (e.g. the corner of your phone hits the ground, the remainder of the phone experiences shock even if it doesn't contact the ground), but a shock test is not always necessarily an impact.

Thankyou for your reply.

Mintu

how to perform droptest in optistruct?

PaulAltair

There is a tutorial in the help, OS-T: 7000 for a phone drop test set up

OS Help Phone Drop

Explicit analysis is a relatively new addition to OptiStruct, you will need at least version 2020.1 to perform this I think, and I would recommend you update to version 2021 if you can (released last week)

Mintu

Paul Sharp_21301 said:

There is a tutorial in the help, OS-T: 7000 for a phone drop test set up

OS Help Phone Drop

Explicit analysis is a relatively new addition to OptiStruct, you will need at least version 2020.1 to perform this I think, and I would recommend you update to version 2021 if you can (released last week)

currently iam using 2019 version. can you guide me in analysis setup for free drop a height of 1.5m above steel plate of 15 mm thick.

PaulAltair

You can't do it in OptiStruct 2019 the functionality wasn't in that version, you could do it in RADIOSS instead in 2019,

There is an example here:

https://support.altair.com/community?sys_kb_id=7b04d8b4db46ac10e8863978f496190c&id=kb_article_view&sysparm_rank=1&sysparm_tsqueryId=b7a903f91b0aec10c4dfdbd9dc4bcb6f

if you are more familiar with OptiStruct set up though, then it might be easier to install 2021 and do it there?

Regarding drop height/velocity in either OS or RADIOSS, you would calculate velocity after drop of 1.5m  (sqrt (2 * g * h)) (approx 5.42m/s) then set that as the initial velocity of your object, and position it just at the point of impact, you should add gravity loading too really, it will make a small difference.

Mintu

Hi sir,

actually i know the calculations, but i dont know how to set up model in radioss? can you help me?

PaulAltair

Have you used RADIOSS at all before? There are a number of example models and a couple of tutorials in the online help that might help you get started.

Did you take a look at the box example in the last post I sent?

It might be worth contacting your local Altair support to see if they have any training coming up, or if they can help you with the model?

 

Mintu

Hi,

currently iam working on drop test. how to get energy graph in radioss hypermesh.

PaulAltair

You can load the T01 file from your analysis in HyperGraph, this contains the energy plots for the simulation:

Kinetic Energy, Internal Energy etc

Mintu

i didn't get any T01 file. how can i get it in analysis folder. i have to request any control card. please suggest me.

PaulAltair

Is the run actually completing successfully? Are you getting animation files (A001,A002 etc?) you can try entering TFILE line in your engine file (0001.rad), syntax is just as below (value being frequency of output):

TFILE

1e-4

Mintu

How to define rigid wall in radioss. there is no option for base node.what is the importance of base node.

Mintu

Paul Sharp_21301 said:

Is the run actually completing successfully? Are you getting animation files (A001,A002 etc?) you can try entering TFILE line in your engine file (0001.rad), syntax is just as below (value being frequency of output):

TFILE

1e-4

Sir,

i got T01 Format. when iam opening this in hypergraph, the graph is not presented in HG. can you help me in plotting energy balance graph.

Mintu

Iam doing drop test analysis for cell phone. iam not getting energy balance graph, any one can help me out?

PaulAltair

Hi, the energy balance, (Internal Energy, Kinetic Energy etc.) can be plotted from the T01 file written from your model

If you can share your model I can show you

Paul

PaulAltair

Mintu said:

Sir,

i got T01 Format. when iam opening this in hypergraph, the graph is not presented in HG. can you help me in plotting energy balance graph.

The T01 if present always contains these values so I am not sure why you are not getting them

Can you share your model?

PaulAltair

Mintu said:

How to define rigid wall in radioss. there is no option for base node.what is the importance of base node.

There is an option for base node (node_id field), you can use base node instead of coordinates to define the wall location, if you are defining a moving wall then you may prescribe displacement on it as you would an RBODY master node.

Mintu

Paul Sharp_21301 said:

Hi, the energy balance, (Internal Energy, Kinetic Energy etc.) can be plotted from the T01 file written from your model

If you can share your model I can show you

Paul

Okie sir, I will try share my model.

and how can i do drop test twisely for the unit. what kind of assumptions i need to considered for drop test simulation?

PaulAltair

You should try to replicate the physical test condition, e.g. static drop or 'tumble' test

You should contact you local Altair Support, they will be able to give you more advice on your specific application

Mintu

Thankyou for your reply sir.

Mintu

Paul Sharp_21301 said:

Hi, the energy balance, (Internal Energy, Kinetic Energy etc.) can be plotted from the T01 file written from your model

If you can share your model I can show you

Paul

Hi sir,

actually iam unable to share my model. sorry for inconvenience. but actually i have gone through RD-3597:CELL PHONE DROP TEST USING Hypermesh. i have got same results. but unable to plot energy balance graph. can you help me in plotting graph?

PaulAltair

Mintu said:

Hi sir,

actually iam unable to share my model. sorry for inconvenience. but actually i have gone through RD-3597:CELL PHONE DROP TEST USING Hypermesh. i have got same results. but unable to plot energy balance graph. can you help me in plotting graph?

What is the issue you are having?, you should be able to read the T01 in hypergraph as below and that will plot the energies requested? (TTE, KE, IE shown)

Mintu

Hi,

Iam doing drop test for electronic unit. for this i have meshed my unit in optistruct user profile. after that i have changed my userprofile to radioss and created loads and boundary conditions. updated my elements to shell4N elements from elements config option. but iam getting error as Error input consistency

2D sOLIDS(Quad & Tria)are not compatible with N2D3D=0

any one can help me out?

Mintu

can anyone explain how to define time step for drop test analysis.

PaulAltair

the stable timestep for the simulation will be automatically calculated, so you don't have to do anything, if you want to modify it you can use /DT/NODA/CST in the engine file (0001.rad) and specify scale factor and timestep, but you should exercise caution for a drop test if doing this, since you don't want to add too much mass and alter the physics of the problem

Mintu

I have performed drop test analysis. but iam unable to get graph files. can anyone help me ?

PaulAltair

What graph files do you need?

The T01 file output (graph data) frequency is set by the /TFILE card in your engine (0001.rad)

The T01 file from your run can be read into hypergraph to plot energies from the model (in the T01 by default), if you need extra data (for example specific time histories for entities in the model) then you need to request those with /TH cards in the run

If you see the replies above, it is shown how to plot the energies

Mintu

Thank you for your answer.

Mintu

how we can decide element size for drop test analysis?