Numerical Stress Analysis of Internal Ring-Stiffened Tubular T-Joints

In order to design a tubular joint to carry a larger load and to possess a longer life, the prime objective of design would be to reduce stress concentration factor at the intersection of the joint; one method to achieve the same is to stiffen the joint with internal ring stiffeners. This paper presents results of the stress analysis for stress distribution, along the intersection of internally ring-stiffened tubular T-joints, under the action of axial and in-plane/out-of-plane (bending) loads, using degenerate shell elements. The stress analyses results are obtained using the general-purpose finite element package called ABAQUS. Post-processing of results has been facilitated by other small programs developed for the purpose. The nominal brace stress and the maximum principal stress values have been used for stress concentration factor computations. The effects of stiffener size, location, number, thickness (τ) and thinness (γ) ratios have been investigated, and the results validated with known analytical and experimental investigations. A comparison of the results obtained from finite element analysis, and experimental results of the Canadian Cooperative Fatigue Studies Program, carried out at Memorial University and University of Waterloo, is also made. The results obtained indicate that stiffening can considerably reduce the stress concentration in joints, and thus increase the load-carrying capacity of tubular T-joints.