Papers by Author: Xiao Ping Huang

Abstract: The calculation of stress intensity factor (SIF) in fracture mechanics-based fatigue life prediction is mainly based on empirical formulas, the poor applicability of which limits the wide application of fatigue assessment based on crack propagation. This paper proposed a SIF calculation method for structures under wave loads. It was proved correct by comparing with the empirical formulas. Then, the method proposed was applied for the surface crack at weld toe of a connection between the column and brace of a semi-submersible platform. The predicted results showed that SIF ranges varied with wave loads, which were subjected to the effects of wave directions and frequencies. In addition, SIF ranges calculated by empirical formulas were very different from those of the proposed method. In order to accurately predict fatigue crack propagation life for ocean engineering structures, it is necessary to take the characters of wave loads into consideration. The proposed method in this paper may provide a reference.

Abstract: The pipe-soil interaction problem is a critical issue in the fatigue analysis of SCR. In this paper, investigation on the initial trench configuration in the touchdown zone (TDZ) of the steel catenary riser (SCR) and factors, which have influence on the trench configuration, such as the amplitude of top end motion were performed firstly. Then the bending moment variation at different points along the trench during the pull up and lay down, the trenches and dynamic response at the touchdown point (TDP) under different soil properties were also investigated. It should be noted that the pipe around the TDZ especially at the TDP, which bears the most drastic bending moment variation and stress variation, is the hot spot in the fatigue analysis of SCR, and the soil properties have big influence on the dynamic stress response amplitude.

Abstract: It is very important to determine the expansion pressure or residual contact pressure of tube-to-tubesheet joint. The expansion pressure and the residual contact pressure are affected by the geometry, material mechanical properties of the tube and tubesheet. In the basic theory of calculating the residual contact pressure of tube-to-tubesheet joints, the elastic-perfectly material is assumed. Because of the strain-hardening of the materials, linear strain-hardening or power strain-hardening were adopted in some analyzing models of the hydraulically expanded tube-to-tubesheet joint. In this paper, a general strain-hardening material model is adopted and an analytical model is proposed and validated by finite element analysis results. The elastic-perfectly model, linear strain-hardening model or power strain-hardening can be the special case of the present model.

Abstract: An autofrettage model considering the material strain-hardening behavior and the Bauschinger effect, based on the actual tensile–compressive curve of material and modified yield criterion, has been proposed. The analytic expressions of residual stress distribution and the autofrettage pressure have been obtained. This model has stronger curve fitting ability, nearly all of the strain-stress curves of materials used in making autoefrettage tubes can be fitted well by this model, and each of those models based on the simplified strain hardening relationship of material is a special case of the model. It was used to predict the residual stress distributions of an autofrettaged tube. The results show that the residual stress distributions predicted by the present model are in good agreement with the experimental data.