Great video, it actually helped me out tons. But beware that there is an error in dN3/dx @10:48 and is further complicated @11:11 when dN3/dx is plugged inside [B]. If you take both equations and evaluate them, you will see they yield different results. To clarify, dN3/dx itself is wrong @10:48 and when plugged in [B] is a whole different equation altogether. Overall, excellent video. Liked
This was fantastic! I'm doing a class project and this was the portion I really needed help with. I'm going to use this method, but I did have one question related to an example in my text: Nam Ho Kim et al. 2009, example 6.10 b. They refers to the B matrix as [B(si,tj)] in their stiffness matrix calculation and don't appear to convert it to x, y coordinates. Are they somehow not converting the B to x,y coordinates and leaving it in s,t coordinates to find the stiffness matrix? Is that something you can do and then convert in the final stiffness matrix?
It is a property of shape function, where the value of N1 when the coordinate of point 1 is (s,t)=(-1,-1) is N1=(1/4)*(1-s)(1-t)=N1=(1/4)*(1-(-1))(1-(-1))=1. And N1 is zero at ALL other three points.
Great video, it actually helped me out tons.
But beware that there is an error in dN3/dx @10:48 and is further complicated @11:11 when dN3/dx is plugged inside [B]. If you take both equations and evaluate them, you will see they yield different results.
To clarify, dN3/dx itself is wrong @10:48 and when plugged in [B] is a whole different equation altogether.
Overall, excellent video. Liked
Thanks for pointing this out. For anyone wondering, the numerator should be 2t-s+1.
nicely done! FEM is quite hard to grab, but u did well in explanation!
This was fantastic! I'm doing a class project and this was the portion I really needed help with. I'm going to use this method, but I did have one question related to an example in my text: Nam Ho Kim et al. 2009, example 6.10 b. They refers to the B matrix as [B(si,tj)] in their stiffness matrix calculation and don't appear to convert it to x, y coordinates. Are they somehow not converting the B to x,y coordinates and leaving it in s,t coordinates to find the stiffness matrix? Is that something you can do and then convert in the final stiffness matrix?
Why is there a 2 in the numerator of the coeeficent of jacobian determinant? There should be an 8 there no?
@ 7:10 Second line, second term should be dy/dt = 1/4* (5+s) not dx/dt? - BTW nicely done.
Why N1=(1/4)*(1-s)(1-t)? can you explain?
It is a property of shape function, where the value of N1 when the coordinate of point 1 is (s,t)=(-1,-1) is N1=(1/4)*(1-s)(1-t)=N1=(1/4)*(1-(-1))(1-(-1))=1.
And N1 is zero at ALL other three points.