Unable to acquire in post-processing for crash simulation of inflated body
Altair EmployeeSir,
I want to perform a crash analysis on an inflated structure. The problem I am facing is about the type of MONVOL to choose. Since its not exactly an airbag, I doubt whether GAS Monvol is to be used. I have performed a simulation with the inflated structure(MONVOL-GAS-Pint-0.2MPa) whose purpose to absorb the energy of impact and prevent the damage to a bullet and a target vehicle. However the postprocessor is showing no deviation in K.E, I.E and Hour glass energy. Even the contour show no particular deformation. How can I quantify the energy absorbed for the same in that case?. I only want the energy absorbed data of 3 bodies, kindly suggest me a solution. I am attaching an image of the hyperview( used monvol-airbag). Is it necessary I give airbag effect or can I move forward with Gas monvol?
<?xml version="1.0" encoding="UTF-8"?>![Airbag_effect_0000[1].png](https://community.altair.com/home/leaving?allowTrusted=1&target=https%3A%2F%2Fvcdn.altair.com%2Frl%2Fforum%2Fuploads%2Fmonthly_2018_03%2F5ab39bfd127cb_Airbag_effect_00001.png.64ee16f706b4aa91ec8f9a62cfff72ae.png)
Answers
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Hi,
Please try with the attached file.
/MONVOL/GAS approach seems fine for this case.
<?xml version="1.0" encoding="UTF-8"?>
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Hi Sir,
Thank you for the prompt response. Can you please tell me what modification I have to make to get the required output?
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Sir, Im using hypermesh 14.0 version . So its not compatible to run and check the above file.Can you please resend the file in rad format
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Radioss 120
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Sir the file is not running.Its directly showing job completed without generating files
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Sir it worked, I dont know what happened initially thanks alot
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Output cards given
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Sir,
My solver time is continously increasing. I have attached the file. Can you please say why is it happening
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Hi,
The time step is dropping which results in increasing run time.
From the engine out files check what is causing this issue. It could be an element, or node or interface.
<?xml version="1.0" encoding="UTF-8"?>
For an element, check the related material.There must not be an error in the units system that this data is given in. check the element size also.
For a node, check the characteristics of connected elements. If the node is on the master side or the slave side of an interface, this interface must be verified.
For an interface, the gap of the interface must be verified if some failure happens on the master or the slave side of the interface. Also check the interface for any penetrations.
Also, you can try imposing a time step in the model (/DT/NODA/CST), ensure that the mass added is less than 5% (.05), which you can monitor in the engine out file.
Please go through https://altair-2.wistia.com/medias/o0bfml9ah5 which is a webinar on time step in RADIOSS.
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Hi sir,
I did a simulation with the inflated airbag as above, but during the postprocessing the graph for I.E,K.E,T.E andHGE, only the Internal energy is varying. Why is the K.E not varying for my model. Is it because it is a airbag fabric with air inside. I am attaching the graph and animation file for your reference. Kindly let me know why is it happening
<?xml version="1.0" encoding="UTF-8"?>
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Hi,
Please share the .h3d and T01 file so that we will review and update you.
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Hi,
In your model there is no much variation in kinetic energy. But there will be and it seems like those values will be of less magnitude compared to the IE values.
Obviously the internal energy of the system is increasing but there is no much variation of kinetic energy in your model.
Plot the KE separately and review if there are any variations.
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Hi sir,
You are right sir. But my doubt is why the global variables are showing no variation? in internal energy MAG.
Sir I have one more doubt regarding admas. How Can I remove admas . For eg., I applied 5 tonnes accidentally, now if I have to reduce it to 3tonne how can I do it?.
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Hi sir,
The above problem is cleared. Sir but while running I am getting node deactivated from interface message. I changed the gap of fabric to 2 from 0.1. Still its showing.Its showing zero penetration and intersections.
<?xml version="1.0" encoding="UTF-8"?>
<?xml version="1.0" encoding="UTF-8"?>
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Sir,
Why is the node getting de-activated from interface. Please reply. Issue is critical. Is it due to giving airbag material properties and applying movol gas instead of monvol airbag?..
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Hi,
This issue seems to arise from the interface 2 in your model. You can recheck the contact created.
The below post shows clearing any penetrations in interface. Please refer it and check for any penetrations:
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Sir,
I have defined two contacts in the simulation. One with Type7 between the car and Inflated body where the master is inflated body and slave is car. The second is the self contact of the inflated body(both master and slave) which is also type 7. I did not define contact between the inflated body and truck since the global variables are showing no variation with that setup . How should vary it?
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Hi,
Please check the interface 2 in your model as the issue seems to arise from this contact.
Try recreating the contact with recommended parameters for Type 7 interface.
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