Cable element

Altair Forum User

I wanna set up the ROD element as a rope initially non tense: it is connected an a sistem that increase strength over time.

Initially the ROD does not resist but when it get to the length granted, it can not have more stretching.

After i calculate the axial FORCE exerted.

 

Regards

Rahul Rajan_21763

Could you share some more information on your problem?

Altair Forum User

Hi @jugerman

FYI, refer to

 

Altair Forum User

HI @Rahul R ,

i have a NLGEOM, an artificial muscle. I wanna calculate the Force that my system is able to generate when the muscle is shortned completely and when the muscle have a shortening of 30% or 50%.
The idea is use a rope: an end is collegate to a node fixed (all costrains activate), while the other end is collegated to the head of muscle (axial point). I wanna understand how i can define the status of rope 'SHORTENED' and the status of rope 'ELONGATED'. In particular i wanna define the 'elongated' status as the muscle get to 30% of initial length (i set manually this parameter). So i wanna create a simulation in which i measure the axial of rope force when it is tension, where 'tension' coincide with an imposted shortening of rope.
I hope I was clear.

 

HI @Prakash Pagadala, I have see it, but i I can not set the parameters, CGAP can be used for my application? 

Regards

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Altair Forum User

Hi @jugerman

 

Since you want to calculate the forces required when the muscle contracts (this is when the rope element expands) GAP elements can come handy when only is required.

 

ROD elements take tension, compression and torsion loads except bending.

 

In order to use GAP elements, Card edit the GAP element(S) using Card edit (shown in red) and change the option to FLIP.

<?xml version="1.0" encoding="UTF-8"?>

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

Thanks @Prakash Pagadala,

 

and how i can define the status of rope 'SHORTENED' and the status of rope 'ELONGATED' ? 

Altair Forum User

Altair Forum User said:

status of rope 'SHORTENED' and the status of rope 'ELONGATED' ? 

Can you please elaborate?

Altair Forum User

Is possible define the length of the rope?

How i must set correctly U0 and KA parameter?

 

I dont understand how define the max elongation of rope. 

During the simulation, the rope have no reaction, it has an undefinited elongation as an elastic element.

Altair Forum User

The length of the rope is defined by the nodes.

 

U0 can be set to automatic and KA is the stiffness.

Altair Forum User said:

During the simulation, the rope have no reaction, it has an undefinited elongation as an elastic element.

Can you explain, what do you mean by no reaction?

Altair Forum User

The CGAP element don't stop the muscle contraction. 

I wanna create a cable element that has a controlled elongation. The muscle may have a shortening that is interrupt when the rope goes into stress.

Altair Forum User

Hi Stefano,

 

Maybe you can use cgapG elements with obstacles.

Altair Forum User

Ok @Prakash Pagadala, but i have found the problem: i must set KB > 0 insted of KB=0

I have try some simulation with KA << 1 and KB>>1 and CGAP work a bit.

Can you help me to understand this situation? Thanks

Altair Forum User

The usage of KA and KB depends on Intial gap opening U0.

 

If gap is closed KA is used and when it is open KB is used. 

Altair Forum User

Thanks for all @Prakash Pagadala

Regards