Dear Ansys Experts / Developers, I have one interesting problem regarding Anisotropic hyperelastic modelling in APDL (AHYPER command_ exponential form) See, we have an inbuilt Userhyper subroutine templet in Ansys to model isotropic user defined the hyperelastic material. In this, we need to supply the strain energy density function and its derivatives with respect to invarients (I1 and I2) to this standard userhyper subroutine templet. Now if I want to model Anisotropic hyperelastic material in Ansys APDL (Assuming the same exponential form of strain energy density function as given in Ahyper command) but using user-defined subroutine. How do I go about it? I would have used same userhyper subroutine but the problem is in anisotropic hyperelastic modelling we have another two invarients (ie I4 and I6). I don't know how to define the derivatives with respect to I4 and I6 in that, as derivatives definition is limited only to I1 and I2 inverients. So my question is there a provision in ANSYS to model user-defined Anisotropic hyperelastic model using subroutine like we use for isotopic hyperelastic using userhyper.f subroutine? if not what are the options or how we can use the same userhyper for anisotropic material? Any help, document links, your demo work in this domain is really appreciated. Thanking you all in advance. Best regards, Sudhir A. IITB

Sudhir: You may want to check the USERMAT subroutine instead. There is an example of the Neo-Hookean hyperelastic model in the technology demonstration guide (TD 38). Harish Harish Radhakrishnan Senior Technical Services Engineer ANSYS Inc 15915 Katy Freeway, Suite 550 Houston, TX 77094 Office: 281-676-7013 *Technical Support*: 1-800-711-7199, www.ansys.com/customerportal harish.radhakrishnan@ansys.com On Sun, Mar 4, 2018 at 11:12 PM, <163104004@iitb.ac.in> wrote: > Dear Ansys Experts / Developers, > > I have one interesting problem regarding Anisotropic hyperelastic > modelling in APDL (AHYPER command_ exponential form) > > > See, we have an inbuilt Userhyper subroutine templet in Ansys to model > isotropic user defined the hyperelastic material. In this, we need to > supply the strain energy density function and its derivatives with respect > to invarients (I1 and I2) to this standard userhyper subroutine templet. > Now if I want to model Anisotropic hyperelastic material in Ansys APDL > (Assuming the same exponential form of strain energy density function as > given in Ahyper command) but using user-defined subroutine. How do I go > about it? > > I would have used same userhyper subroutine but the problem is in > anisotropic hyperelastic modelling we have another two invarients (ie I4 > and I6). I don't know how to define the derivatives with respect to I4 and > I6 in that, as derivatives definition is limited only to I1 and I2 > inverients. So my question is there a provision in ANSYS to model > user-defined Anisotropic hyperelastic model using subroutine like we use > for isotopic hyperelastic using userhyper.f subroutine? if not what are > the options or how we can use the same userhyper for anisotropic material? > > Any help, document links, your demo work in this domain is > really appreciated. Thanking you all in advance. > > Best regards, > Sudhir A. > IITB > > > > > > > _______________________________________________ > Xansys-temp mailing list > Xansys-temp@xansystest.info > http://xansystest.info/mailman/listinfo/xansys-temp_xansystest.info > If you are receiving too many emails from XANSYS please consider changing > account settings to Digest mode which will send a single email per day. > > Please send administrative requests such as deletion from XANSYS to > xansys-mod@tynecomp.co.uk and not to the list >

I second this recommendation. In a previous life, our team always used USERMAT as a starting point. If memory serves, you will be far less likely to run into limitations. This assumes of course you have a well-written material model. (Don't 'boil the ocean', by the way, make sure you can get a basic nonlinear model working in USERMAT first.) Matthew Pausley | Mechanical Analyst | Nuvotronics, Inc 2305 Presidential Drive | Durham, NC 27703 | mpausley@nuvotronics.com www.nuvotronics.com -----Original Message----- From: Harish Radhakrishnan [mailto:harish.radhakrishnan@ansys.com] Sent: Monday, March 05, 2018 6:08 AM To: XANSYS Mailing List Temporary Home <xansys-temp@xansystest.info> Subject: Re: [Xansys] Xansys_APDL_Userhyper subroutine_Ahyper command Sudhir: You may want to check the USERMAT subroutine instead. There is an example of the Neo-Hookean hyperelastic model in the technology demonstration guide (TD 38). Harish Harish Radhakrishnan Senior Technical Services Engineer ANSYS Inc 15915 Katy Freeway, Suite 550 Houston, TX 77094 Office: 281-676-7013 *Technical Support*: 1-800-711-7199, www.ansys.com/customerportal harish.radhakrishnan@ansys.com On Sun, Mar 4, 2018 at 11:12 PM, <163104004@iitb.ac.in> wrote: > Dear Ansys Experts / Developers, > > I have one interesting problem regarding Anisotropic hyperelastic > modelling in APDL (AHYPER command_ exponential form) > > > See, we have an inbuilt Userhyper subroutine templet in Ansys to model > isotropic user defined the hyperelastic material. In this, we need to > supply the strain energy density function and its derivatives with > respect to invarients (I1 and I2) to this standard userhyper subroutine templet. > Now if I want to model Anisotropic hyperelastic material in Ansys APDL > (Assuming the same exponential form of strain energy density function > as given in Ahyper command) but using user-defined subroutine. How do > I go about it? > > I would have used same userhyper subroutine but the problem is in > anisotropic hyperelastic modelling we have another two invarients (ie > I4 and I6). I don't know how to define the derivatives with respect to > I4 and > I6 in that, as derivatives definition is limited only to I1 and I2 > inverients. So my question is there a provision in ANSYS to model > user-defined Anisotropic hyperelastic model using subroutine like we > use for isotopic hyperelastic using userhyper.f subroutine? if not > what are the options or how we can use the same userhyper for anisotropic material? > > Any help, document links, your demo work in this domain is really > appreciated. Thanking you all in advance. > > Best regards, > Sudhir A. > IITB > > > > > > > _______________________________________________ > Xansys-temp mailing list > Xansys-temp@xansystest.info > http://xansystest.info/mailman/listinfo/xansys-temp_xansystest.info > If you are receiving too many emails from XANSYS please consider > changing account settings to Digest mode which will send a single email per day. > > Please send administrative requests such as deletion from XANSYS to > xansys-mod@tynecomp.co.uk and not to the list > _______________________________________________ Xansys-temp mailing list Xansys-temp@xansystest.info http://xansystest.info/mailman/listinfo/xansys-temp_xansystest.info If you are receiving too many emails from XANSYS please consider changing account settings to Digest mode which will send a single email per day. Please send administrative requests such as deletion from XANSYS to xansys-mod@tynecomp.co.uk and not to the list This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error, please notify the sender immediately of that fact by return e-mail and permanently delete the e-mail and any attachments.