Welding Mechanics Laboratory (WML)

In the early 1900’s, the Swedish marine engineer Oscar Kjellberg introduced the shield arc welding process to the world (stick welding), by his patent on the flux-coated electrodes in 1907. Its original purpose was the repair welding of riveted boilers and other broken machinery structures. In 1920, M/S ESAB IV, the world’s first ship with a fully welded hull, was built by Oscar Kjellberg’s company ESAB. Since then, arc welding technology, with continuous development and improvement, has become an established process for the manufacturing, maintenance, and repair of metal structures.

Today, it is understood that the ultimate mechanical properties of a welded structure depend upon an intricate relationship between several contributing factors. Here at the Welding Mechanics Laboratory (WML) we are, by the use of systems engineering and Computational Welding Mechanics (CWM), studying how various physical phenomena influence the Fitness For Service (FFS) of metallic structures.

Computational Welding Mechanics (CWM)

CWM is the numerical modelling and experimental verification of weld joint related phenomena for understanding and description of how a particular Welding Procedure Specification (WPS) influences the Weld Residual Strains and Stresses (WRS) magnitude, the Weld Residual Affected Zone’s (WRAZ) geometry, fracture mechanics (LEFM and EPFM), and fatigue crack growth properties.

Fitness for Service (FFS) and Seaworthiness

By the understanding of how the technical life time of a metallic structure is affected by the manufacturing engineering processes (material specifications, forming, joining, heat treatment and machining etc) in combination with the structure’s actual operative thermal, mechanical and/or chemical boundary conditions, one can approximate the safe operational lifetime of complex metallic structures and increase the commercial competitiveness.

The ultimate purposes of FFS and Seaworthiness analysis are safeguarding and/or assurance of:

1. Human life
2. Environment
3. Structural integrity of assets
4. Commercial operative availability
5. Laws, rules and regulations

Wire Arc Additive Manufacturing (WAAM)

Robotic wire arc additive manufacturing (WAAM) is a rapidly developing technology with great promises for the society. This is mainly due to its opportunity to, in a relatively short design-production time cycle, produce fully dense near net shape metallic structures with complex geometries. By the use of our in-house integrated 7-axis WAAM robot unit, we study how one should proceed to produce robust WAAM structures intended for energy, marine and heavy industrial applications.

Metrology

In conjunction with experimental activities, data acquisitioning (DAQ) is carried out. Metrology, the science of measurement, is subsequently of an interest to understand and quantify the collected data’s magnitude of uncertainty.

Health, Safety and Environment (HSE)

Arc welding is a multi-physical process emitting energy and chemical components in various forms that very well can be hazardous for the operator, the community and/or the environment. Therefore, it is desirable to understand and mitigate the potential HSE risks associated with welding operations.

Investigation and Advisory

WML undertakes investigation and advisory projects on a commercial basis. We have delivered welding, material, seaworthiness and FFS training, advisory and investigations since 2017, to the following organizations:

• Tranter International AB, Sweden
• Bassoe Technology AB, Sweden
• FKAB, Sweden
• FOWIC AS, Norway
• Lavaretus Underwriting AB, Sweden
• Master Marine AS, Norway
• SEMAR AS, Norway
• VEQTER Ltd, United Kingdom
• Wisby Tankers, Sweden