Abaus mesh elements

[fisken90]

Hi everybody. I'm doing a shear test of a pin. Today I stumbled upon an something interesting. With C3D20 elements, I get a stress of 710 MPa and with C3D8 elements I get 370 MPa. Even if I use finer C3D8 elements it will not get as high as 710 MPa. Anyone know a reason for this?

Pictures:

http://files.engineering.com/getfil...-be1c-4f6c-924b-5859318e3f16&file=Capture.JPG

http://files.engineering.com/getfil...0148-4458-a198-ac4aa7b49761&file=Capture2.JPG

Thanks in advance

 

[Mustaine3]

Probably shear locking.
See Getting Started 4.1 Element formulation and integration

Try C3D8I elements.

 

[fisken90]

As I understand, shear locking usually happens with long, thin elements with high bending. My shear test only have a displacement of o.3 mm of a 40mm long pin.

 

[DrBwts]

That's close to 1% strain which is pretty high for a lot of materials.