Hello,
I am currently trying to develop a model for the insertion of needles into human skin using Abaqus/Explicit with the VUSDFLD user subroutine for element deletion. I am using a maximum principal strain failure criterion, where if the magnitude of principal strain exceeds the critical strain threshold, the element is subsequently deleted. I have set element deletion=yes in the mesh module for the skin, and requested the STATUS variable as a field output request. I have set Depvar delete=1, where 1 is defined as the STATUS variable. When running the simulation, elements are being deleted as expected, however after the first set of elements are deleted, the skin springs back and the needle intersects with the skin elements, then progresses "through" the skin without any contact. I have tried numerous contact methods from the literature, I am currently using General contact with a penalty contact algorithm for tangential friction. I am struggling to understand why contact is lost between the two bodies, and would greatly appreciate any advice from other people who have had a similar issue. I have attached a photo of the intersection after the first elements are deleted for reference. I am currently running a demo problem in 2D, with a relatively coarse mesh and blunt needle before moving to the full 3D model.
Thanks in advance for your help.
I am currently trying to develop a model for the insertion of needles into human skin using Abaqus/Explicit with the VUSDFLD user subroutine for element deletion. I am using a maximum principal strain failure criterion, where if the magnitude of principal strain exceeds the critical strain threshold, the element is subsequently deleted. I have set element deletion=yes in the mesh module for the skin, and requested the STATUS variable as a field output request. I have set Depvar delete=1, where 1 is defined as the STATUS variable. When running the simulation, elements are being deleted as expected, however after the first set of elements are deleted, the skin springs back and the needle intersects with the skin elements, then progresses "through" the skin without any contact. I have tried numerous contact methods from the literature, I am currently using General contact with a penalty contact algorithm for tangential friction. I am struggling to understand why contact is lost between the two bodies, and would greatly appreciate any advice from other people who have had a similar issue. I have attached a photo of the intersection after the first elements are deleted for reference. I am currently running a demo problem in 2D, with a relatively coarse mesh and blunt needle before moving to the full 3D model.
Thanks in advance for your help.
