Alejalo88
Subscriber
Hi Ishan Thanks for your reply!!!!!
I will try to explain my question with pictures then:
The subject is about the stress analysis of a welded tubular T joint in Ansys Mechanical APDL as seen on the picture below (the thickness of the tubular members is 8mm). A unit axial load is applied at the top of the brace (vertical member). A symmetry boundary condition is applied at the XY and YZ planes (only a quarter of the T joint is modelled). A fixed support is applied at the end of the chord member (horizontal member).
I have 2 finite element models:
The first model meshed with SHELL181 elements, the mesh density is adjusted until I get a mesh convergence of less than 3% between the nodal and the element solutions at the location of highest stress.
3 shell sections are specified:
A first shell section type is applied to the brace member (vertical member) specifying a thickness of 8mm, 5 integration points and a midplane section offset.
A second shell section type is applied to the chord member (horizontal member) specifying a thickness of 8mm, 5 integration points and a top plane section offset.
A third shell section type is applied to the geometry representing the weld specifying a thickness of 7.82mm (average thickness of the weld geometry along the tubular joint intersection), 5 integration points and a midplane section offset.
The axial load is applied using TARGE170 and CONTA175 elements at the top of the brace (vertival member) as shown on the picture below (force-distributed constraint):
The fixed support is applied using TARGE170 and CONTA175 elements at the end of the chord member (horizontal member) as shown on the picture below (coupling constraint):
The second model meshed with SOLID186 elements, I have 5 elements through the thickness of the tubular members and I get a full convergence between the nodal and the element solutions at the location of highest stress.
The axial load is applied using TARGE170 and CONTA174 elements at the top of the brace (vertival member) as shown on the picture below (force-distributed constraint):
The fixed support is applied using TARGE170 and CONTA174 elements at the end of the chord member (horizontal member) as shown on the picture below (coupling constraint):
I am reading the 1st principal stresses at the locations as shown on the picture below for both finite element models.
The results show me that at the chord saddle and at the chord crown the stresses for the solid elements are lower than those for the shell elements.
But at the brace saddle and at the brace crown the stresses for the solid elements are higher than those for the shell elements.
The deformed shape of the structure looks like on the picture below. It is apparent that on the chord member I am having more bending than membrane behaviour while on the brace member I am having more membrane than bending behaviour (Am i correct?).
And so my question is which element should give higher stresses in which behaviour.
Is it correct to assume that the shell elements give higher stresses in bending and the solid elements give higher stresses in membrane behaviour?????
Thank you so much in advance Alejandro Santacruz