Geometric tolerances of tubular T-joint test-specimens

Abstract

The objective of present work is estimation of geometric tolerances of fabricated laboratory test-models from 3D CAD models. A set of 7 welded S355 steel specimens with T-joint design have been investigated. The specimens, with nominal dimensions ø114 mm for the brace and ø219 mm for the chord imitate a typical welded T-connection widely met in offshore structures like oil rigs and is to be used for fatigue testing at the UiS lab facilities. As a result of the study 3D CAD models of the test-specimens were acquired with the use of laser scanning tool “HandyScan 3D” combined with the Creaform CAD software. This study investigates weld geometry requirements covered in standard AWSD1.1 On the basis of the standard requirements 3D models of reference weld geometry were modelled in Autodesk Inventor CAD application. One model for least material condition (LMC) and another for maximum material condition (MMC) weld profile. Later on the scanned meshes of specimens is compared with reference models resulting in virtual validation reports made in VXelements environment. Geometric tolerances of weld and the assembly are estimated and compared with the values measured during virtual validation. General conclusion is that the scanned weld geometry of real specimens in every case exceeds the upper limits of allowable weld shape deviation. It is a safe approach from manufacturing side, however it does not provide an optimal fatigue resistant weld profile delivered by the AWSD1.1 standard.