Learning Forum

[18409680]

Hey guys,

I've been working on modelling the HASEL actuator, specifically the peano HASEL actuator ( demonstrated in the following video). https://www.youtube.com/watch?v=-TKjJBZEZe4

I'm having trouble matching my simulated results with the practical results. before showing how I modelled the HASEL actuator below in Fig 1. shows how the HASEL actuator should look when it is 'fully strained'.

[18409680]

Here are the files that I have been runningn nFirst with the transducer elements supplying the force and  then with the penalty method setting the electrode displacement.nn

[dlooman]

The retraction of the acuator is a large deflection effect and the input has the nlgeom command commented out. With nlgeom,on the model won't converge so that may be the reason it is commented out. The plane183 mesh is very poor due to the thinness of the geometry. This may contribute to the convergence difficulty. A shell element would be more appropriate for such thin geometry (after converting the model to 3D by giving it a unit depth. ) Applying the pressure gradually over many steps may be necessary also. The analysis of thin membranes under internal pressure is always difficult and not always possible. A command like STABILIZE may help.n

[18409680]

Thanks dlooman,nYes, I had to comment out the 'nlgeom,on' because it was highly distorted my geometry. nI did think of the thinness of the model and recently tried to do the simulation BEAM element. nI was able to mesh with 'nlgeom,on' working.nhowever the issue now is the contact stiffness of the TRANS126 is not taking over when the beam element reaches the 'minimum gap' as described in the TRANS126 element description. No matter what I change the beam elements just pass right through each other and thus the electrode can't 'zip', as shown in the figure below. Even when I try to add a contact element it still does nothing. nShould I try it with the 3D shell model? Is it more compatible with contact stiffness? Or is there something wrong with the way I have used the TRANS126 element?nHere are all the codes associated with the TRANS element (the scale is in umks units)n pouch_thickness = 20n pouch_width = 100e3nelectrode_mat=3npermittivity_of_air = 8.85e-6n relative_permittivity = 2.1n permittivity = relative_permittivity*permittivity_of_airnMP, PERX, electrode_mat, permittivityt!nLSEL,NONE  nLSEL,S, , ,    6 nNSLL,S,0nCM,ELECT1,NODEnnLSEL,NONE  nLSEL,S, , ,    7nNSLL,S,0nCM,ELECT2,NODEnn*do,i, 1, no_of_coup_pairs,nCMGRP, ELECT_COUP_%i%,Elect1n*do,j, 2, no_of_electnCMEDIT, ELECT_COUP_%i%, add, Elect%j%n*enddon*enddonn*do,i, 1,no_of_elect, nnALLSEL,allnCMSEL,S,ELECT%i%,nn*get, n_count_elect, node,, COUNT,n*DIM, initial_ny%i%, ARRAY, n_count_elect, n*VGET, electrode%i%_nodes, NODE, , nlist,n*do, j, 1, n_count_elect,ninitial_ny%i%(j)= ny(electrode%i%_nodes(j))n*enddon*enddonnET, electrode_mat,TRANS126  n!*  nKEYOPT,electrode_mat,2,2nKEYOPT,electrode_mat,3,0nKEYOPT,electrode_mat,4,0nKEYOPT,electrode_mat,6,0n!* n nTYPE,  electrode_mat  nMAT,telectrode_matnESYS,    0  nSECNUM, nntt! 3.4.1. Divide into Elementsn*do,i, 1, no_of_coup_pairs,nii= i+1nallseln*do,j, 1, n_count_elect, ntrans_I_node= electrode%i%_nodes(j)ntrans_J_node= electrode%ii%_nodes(j)nnGAP=DISTND(trans_I_node,trans_J_node)nGAPMIN= pouch_thicknessnarea= ARNODE(trans_I_node)*pouch_widthnKN= pouch_Ex*pouch_width*area/pouch_thicknessnC0= -permittivity*area!/scale_mnnr, electrode_mat+j-1, , , GAP, GAPMIN, KN, ,nrmore, C0, !C1, C2, C3, C4nreal,electrode_mat+j-1nE,trans_I_node,trans_J_noden*enddon*enddonnThanks for all the helpnLevin

[18409680]

Hey dlooman,nI just noticed that my material don't have a contact coefficients defined accept for the stiffness constant defined in with the TRANS126 element. Would that effect the contact force of the elements or should the TRANS126 stiffness be enough? nLevin

[18409680]

Hey dlooman,nI realized the TRANS126 was backwards, so I switched the nodes around and the contact stiffness for the element now seem to be working.nI now seem to just have an issue of converging all the model with all the TRANS126 forces involved. nHere the latest file I've been using nIf there are any suggestion to help with the convergence it would be much appreciatednLevin