Learning Forum

[Abdulsalam]

Dear all,

I am working on a project to simulate Dielectric Elastomer Actuator under cyclic loading using ANSYS APDL. when I was doing the experimental test for the elastomer membrane I Pre-Stretch it then I applied the voltage across the electrodes. The Pre-Stretch was preformed as shown on the attached photo below. So, now I want to perform the Pre-Stretch so I can compare the experimental result with the simulation. Can anyone tell me how to do it please?

[John Doyle]

I might not be fully understanding your question, but it sounds like you want to simulate a structural-electric analysis with a hyperelastic material to compare with test results? If so, refer to the SOLID226 element documentation in Mechanical APDL Elements Manual for details of what your multiphysics options are. nAssuming you have already curve fitted your material test data to a hyperelastic material model, use SOLID226, with KEYO(1)=1001 to get UX, UY, UZ and VOLT DOF set. You can apply the initial stretch to the membrane in LS1 and apply the electric potential difference at LS2.n

[Abdulsalam]

Dear,nThank you for your response really appreciate it.nYes I am simulating an electrostatic-structural analysis and I have already done all what you mentioned above. And what I meant by Pre-Stretching the membrane is the same to what you mentioned (initial stretch). So I need to do initial stretch to the membrane , then apply the voltage across the electrodes. So, is it really possible to do the initial stretch? Can elaborate more in what is LS1 and LS2 ? My knowledge in ANSYS APDL is quit limited and it is my first time to simulate Dielectric Elastomer Actuator.nnThank you in advance, n

[peteroznewman]

LS means Load Step. Please open ANSYS Help, go to the Mechanical APDL section and read the Basic Analysis Guide. You can copy paste the text below into the address bar after you have opened ANSYS Help. Chapter 3 is on Loading. nhttps://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v211/en/ans_bas/Hlp_G_BasTOC.htmlnis saying apply the initial stretch in Load Step 1. Do this by using a Displacement boundary conditions. I suggest you use a Cylindrical Coordinate System where you can apply a radial displacement (x-axis) on all nodes around the edge while keeping the tangential (y-axis) and axial (z-axis) set to zero. Then in Load Step 2, you can apply the voltage.n

[Abdulsalam]

Dear,nThank you for your response. I have read the ANSYS APDL help that you suggested but I come into conclusion that it is not possible to preform the initial stretch for hyperelastic material. please correct me if I am wrong. nIf you don't mind I want your valuable knowledge and feedback regarding my simulations of DIELECTRIC ELASTMER ACTUATOR I have already written the commands that I believe are needed. But, whenever I run the simulation I can not see any actuation or in other word the elastomer film should contracts in the thickness direction and expands in the film plane directions. I do not know what else I can do. I have read the Coupled-Field Analysis Guide but still cannot get answer and I am running out of time. I have copied the commands bellow. Any suggestions or recommendations are much appreciated n/OUTPUT,APDL SIMULATION TESTS 16,outn/TITLE, DIELECTRIC ELASTOMER ACTUATORS n!!!!!! MATERIAL Parameters n*SET,eps,8.854e-12 ! electrical permittivity, n*SET,V,8000 ! Applied voltage nn!!!!!! element selection and Identifying the propertiesn/PREP7nET,1,SOLID226,1001nKEYOPT,1,11,1nmp,PERX,1,epsnnlgeom,on !! active large deflection nnsub,30 !! number of substeps nautots,offnn!!!!!!!!!!!!! Geometry creationnK,1,0,0,0, nK,2,60e-3,0,0, nK,3,60e-3,60e-3,0, nK,4,0,60e-3,0, nFLST,2,4,3 nFITEM,2,1 nFITEM,2,2 nFITEM,2,3 nFITEM,2,4 nA,P51X nVOFFST,1,0.4e-3, , nVA,1,2,3,4,5,6,!!!!!!!!!!! MESHING nTYPE,1nMAT,1nESIZE,1e-3nVMESH,1n!!!!!!! choosing the hyperelastic model nTBFT,EADD,1,UNIA,TEST16_UNIA_1.exp nTBFT,FADD,1,HYPER,MOON,9nTBFT,SOLVE,1,HYPER,MOON,9,1 nTBFT,FSET,1,HYPER,MOON,9n!!!!!!!!!!!!!! STRUCTURAL BOUNDARY CONDITIONSnnsel,s,loc,y,0 nd,all,all,uy,0 nnsel,r,loc,x,0 nd,all,all,ux,0 nnsel,r,loc,z,0 nd,all,all,uz,0 nnsel,allsel,s,loc,y,60e-3 nd,all,all,uy,0 nnsel,r,loc,x,60e-3 nd,all,all,ux,0 nnsel,r,loc,z,0.4e-3 nd,all,all,uz,0 nnsel,allsel,s,loc,x,0 nd,all,all,ux,0 nnsel,r,loc,y,0 nd,all,all,uy,0 nnsel,r,loc,z,0 nd,all,all,uz,0 nnsel,allsel,s,loc,x,60e-3 nd,all,all,ux,0 nnsel,r,loc,y,60e-3 nd,all,all,uy,0 nnsel,r,loc,z,0.4e-3 nd,all,all,uz,0 nnsel,alln!!!!!!!!!!!! Electrical BCn!!!!!!!!!!!! Ground electrode nnsel,s,loc,z,0nnsel,r,loc,x,20e-3,40e-3nnsel,r,loc,y,20e-3,40e-3ncp,1,volt,alln*SET,ng,ndnext(0)nnsel,alln!!!!!!!!!!!! positive electrode nnsel,s,loc,z,0.4e-3nnsel,r,loc,x,20e-3,40e-3nnsel,r,loc,y,20e-3,40e-3ncp,2,volt,alln*SET,nl,ndnext(0) nnsel,allnn/Solunantyp,staticnd,ng,volt,0nd,nl,volt,VnSOLVEnnThank you In Advance.n