Learning Forum

[Ffatihkaraoglu]

I performed the stent analysis from the ANSYS course using two different materials: 316L (stainless steel) and Ti6Al4V (titanium alloy).

When I examined the results, I found that the safety factor and fatigue life of 316L were better than those of the titanium alloy. I used the material properties from ANSYS's library (and I got the same results when I manually added the materials).

Is it normal for 316L to perform better than the titanium alloy?
(There are no errors in contacts, mesh, boundary conditions, or material properties.)

[danielshaw]

It is impossible to say without knowing more details about the model.  However, the stress reported in the stainless steel model is much less than the stress in the titanium model, so it is not surprising that the safety factor and predicted life are larger.  You need to compare the properties (particularly E and CTE) for each material to assess wihy stainless produces less stress than the titanium.

[Ffatihkaraoglu]

The material properties are as follows and I made 2 types of linear/non-linear analysis.

[danielshaw]

That information is of limited value to me.  You need to assess how those material properties affect the stress developed in your model based on the applied boundary conditions.  For example, a brief review of the properties indicates that stainless has a much lower YS than does tintanimum.  Thus, if the loading is displacement controlled (e.g., thermal expansion or forced displacement) and the developed stress exceeds the stainless YS but not the titanimum YS, then stainless will deform much easier (tangent modulus is much less than E) and not develop as much stress.  I cannot assess those conditions for you.  I do not have access to your model.  You need to examine your model and determine how the material properties affect the developed stress, but it seems feasible that for some sets fo BCs a stainless model could develop less stress.  If you do not have a background in stress analysis and cannot determine the effect the material properties have on the developed stress, you might want to run a series of test cases with modified material properties to assess how changing some properties (e.g., E, CTE, YS, tangent modulus, etc) affect the developed stresses.  Maybe with that data, you can determine why the stainless develops less stress than the titanium.