Welding mechanics for advanced component safety assessment

doi:10.1007/s11706-011-0138-0

Front Mater Sci

2011, Vol. 5

Issue (2) : 224-235 https://doi.org/10.1007/s11706-011-0138-0

RESEARCH ARTICLE

Welding mechanics for advanced component safety assessment

Dieter SIEGELE(

)

Fraunhofer Institute for Mechanics of Materials IWM, W?hlerstr. 11, 79108 Freiburg, Germany

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Abstract

Numerical methods are nowadays a useful tool for the calculation of distortion and residual stresses as a result from the welding process. Modern finite element codes not only allow for calculation of deformations and stresses due to the welding process but also take into account the change of microstructure due to different heating and cooling rates. As an extension to the pure welding simulation, the field of welding mechanics combines the mechanics and the material behaviour from the welding process with the assessment of service behaviour of welded components. In the paper, new results of experimental and numerical work in the field of welding mechanics are described. Through examples from automotive, nuclear and pipe-line applications it is demonstrated that an equilibrated treatment and a close interaction of “process”, “properties” and “defects” are necessary to come up with an advanced fitness-for-service assessment of welded components.

Keywords welding simulation residual stress defect assessment fracture mechanics

Corresponding Author(s): SIEGELE Dieter,Email:dieter.siegle@iwm.fraunhofer.de

Issue Date: 05 June 2011

Cite this article:

Dieter SIEGELE. Welding mechanics for advanced component safety assessment[J]. Front Mater Sci, 2011, 5(2): 224-235.

URL:

https://academic.hep.com.cn/foms/EN/10.1007/s11706-011-0138-0
https://academic.hep.com.cn/foms/EN/Y2011/V5/I2/224

Fig.1 The welding mechanics triangle.

Fig.2 Space frame structure of AUDI A2 and detail of connection between B-pillar and roof profile.

Fig.3 Yield stress versus temperature for different material zones in ENAW6060 (T7-laser weld); True stress-strain curves from room temperature (RT) to 500°C.

Fig.4 Calculated and measured temperature profiles for LB-weld No. 1 in automotive structure.

Fig.5 Calculated and measured melt pool geometries (red: calculated temperatures above melting at 600°C; grey: derived from macro-sections).

Fig.6 Calculated temperature fields at different selected times in LB-welds Nos. 1-3.

Fig.7 Calculated distortion after welding sequence 1-2-3 and release of clamping devices in comparison with original component geometry (line contours).

Fig.8 Transverse and longitudinal residual stresses on the side of the cast B-pillar in LB-weld No. 3 - comparison between calculated (solid lines) and measured values (dashed lines).

Fig.9 Maximum calculated displacement at the end of the roof beam for the investigated parameter variations [].

Fig.10 Macrograph of EB-weld cross section for ARIANE 5 booster with main zones of interest.

Fig.11 Fracture toughness at RT of different micro-structural zones in ARIANE 5 booster EB-weld.

Fig.12 Defects in EB-welded D6AC model-vessels before burst testing.

Fig.13 Sub-scale pressure vessel No. 2 with surface defect after burst test and comparison of experimental and calculated burst pressures.

Fig.14 Geometry of the core shroud with weld passes and finite element mesh.

Fig.15 Residual axial stresses in the flange weld at room and at service temperatures.

Fig.16 SIFs for circumferential, constant depth cracks located at the outer surface in the HAZ of the upper core weld; Redistribution of axial residual stresses due to 41.3 mm deep crack.

Fig.17 Structure of the FKM Guideline “Fracture Mechanics Proof of Strength for Engineering Components”, 3rd edition 2005 [].

Fig.18 Assessment of a defect in spiral welded pipe (FKM Guideline [], worked example No. 7).

Fig.19 Fracture mechanics proof of strength for spiral welded pipe with crack like defect.

Fig.20 Probabilistic failure assessment of defects in the spiral welded pipe line - influence of statistical distribution of the defect size and of the fracture toughness .

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