dc.description.abstract | In this paper, a material characterization inverse methodology is used to obtain
structural parameters for all welded joint regions. Furthermore, such are applied for
the more realistic analysis of the pipeline numerical model structural response.
Material characterization methodology included tensile testing of specimen
containing welded joint. During the experiment strain field was continuously
measured using stereo cameras, and results are processed using system based on
Digital Image Correlation. Numerical computational model of test pipe is formed
using the same parameters, as in the experiment (shape of welded joint, boundary
conditions, loads, etc.). To improve numerical model, deformations of all regions of
welded joint (base material, weld metal, and heat affected zone) are imported into
numerical model. Consequently, material properties (Young’s modulus of elasticity,
yield strength, tensile strength) of all three welded joint regions were obtained.
Material properties are then used in analysis of welded joint influence to structural
integrity. Three different numerical computational models are produced. The first
model represents the classical approach in which the welded joint parameters are
not considered. The second model contained welded joints, but with orientational
mechanical properties of base and weld metal, and with heat affected zone having
properties same as base material. The third one included properties of all three
welded joint regions, obtained using inverse methodology. Results showed that there
is no difference between the models during service operations (elastic structural
behaviour). However, within the plastic deformation domain, which for instance,
accounts for hydraulic shocks, the differences are considerable. When orientational
mechanical properties of base and weld material are included, stress concentration
in welded joint is 1.59. When real properties of material are included, stress
concentration is decreased to 1.49, while stress gradient in welded joint area is
smaller than in previous model. Thus, welded joint modelling can vastly influence the
plastic domain structural behaviour of the pipeline structure. | sr |