dankoonFANTOMAS
Aerospace
- Jun 1, 2016
- 31
Hello everyone
I am using USDLFD subroutine in FORTRAN to model a component with 2 materials and smooth transition btwn both.
I based my work on the functionally graded structure and volume fraction. I used a sigmoid law in order to have a continous transition btw both materials.
I subdivided my problem in the regions like in the picture:
My goal is to reduce the stress concentration of this model:
The stress concentration for a material with E=375GPa is:
So i want to put a material with E=72GPa on the left and make a smooth transition to E=375GPa (to the right) In order to reduce stress on the hole. I used USDFLD subroutine with a if loop to assign different function to the FV depending on the position of the integration points.
So I intend to obtain smaller value than the one material case. But instead of that I always get a stress pick concentration for z=Zi as shown in the plot:
I always saw that an exponential law was used for FGM modeling, this does not required if loop but it is not possible to really control material distribution with it. I found that sigmoid la was more precise but it's like if I had discontinuities in the stress.
Do you think it is because of the condition in the if loop?
Thx
I am using USDLFD subroutine in FORTRAN to model a component with 2 materials and smooth transition btwn both.
I based my work on the functionally graded structure and volume fraction. I used a sigmoid law in order to have a continous transition btw both materials.
I subdivided my problem in the regions like in the picture:
My goal is to reduce the stress concentration of this model:
The stress concentration for a material with E=375GPa is:
So i want to put a material with E=72GPa on the left and make a smooth transition to E=375GPa (to the right) In order to reduce stress on the hole. I used USDFLD subroutine with a if loop to assign different function to the FV depending on the position of the integration points.
So I intend to obtain smaller value than the one material case. But instead of that I always get a stress pick concentration for z=Zi as shown in the plot:
I always saw that an exponential law was used for FGM modeling, this does not required if loop but it is not possible to really control material distribution with it. I found that sigmoid la was more precise but it's like if I had discontinuities in the stress.
Do you think it is because of the condition in the if loop?
Thx