Hi guys,
I'm analyzing the the buckling of axially compressed cylindrical shells using riks procedure in abaqus. After analysis, when I plot the LPF vs displacement (radial displacement of a node in the buckle region) I notice some regions of abrupt variations and overlaps in the curve, which is not expected. I have attached a snapshot of that.
I found a similar example in the abaqus documentation, what they say is to "tighten the force residual convergence criteria" now, how do I do that?
This is what the documentation says:
"The modified Riks method is used to obtain a solution since the problem under consideration is unstable. The Riks method can also be used to trace the unstable and stable solution branches of a buckled structure. However, with imperfection-sensitive structures the first buckling mode is usually catastrophic, so further continuation of the analysis is usually not undertaken. When using the *STATIC, RIKS option, the tolerance used for the force residual convergence criteria may need to be tightened to ensure that the solution algorithm does not retrace its original loading path once the limit point is reached. Simply restricting the maximum arc length allowed in an increment is normally not sufficient."
Thanks,
I'm analyzing the the buckling of axially compressed cylindrical shells using riks procedure in abaqus. After analysis, when I plot the LPF vs displacement (radial displacement of a node in the buckle region) I notice some regions of abrupt variations and overlaps in the curve, which is not expected. I have attached a snapshot of that.
I found a similar example in the abaqus documentation, what they say is to "tighten the force residual convergence criteria" now, how do I do that?
This is what the documentation says:
"The modified Riks method is used to obtain a solution since the problem under consideration is unstable. The Riks method can also be used to trace the unstable and stable solution branches of a buckled structure. However, with imperfection-sensitive structures the first buckling mode is usually catastrophic, so further continuation of the analysis is usually not undertaken. When using the *STATIC, RIKS option, the tolerance used for the force residual convergence criteria may need to be tightened to ensure that the solution algorithm does not retrace its original loading path once the limit point is reached. Simply restricting the maximum arc length allowed in an increment is normally not sufficient."
Thanks,
