Multiaxial loading of thermoplastic laser welds

The number of laser welded applications in industry is rising steadily. For example, laser welding of polymers is used in the automotive, household and medical sectors. In these areas, a high focus on long-term durability and reliability of laser welds is required. The laser welds are exposed to several types of loading, such as ambient conditions, variable amplitude loading and multiaxial loading. Multiaxial loading causes a multiaxial stress state in the laser weld line. However, the determination of such multiaxial stress states presents a challenge. The interactions of different types of loading, such as tension, torsion and in or out of plane loading, especially for cyclic loading, have not yet been examined comprehensively. Test specimens for determining the influence of such parameters on long-term durability of laser welds are not widely available. This paper presents the results for multiaxial loading on thermoplastic laser welds. Therefore, the MultiWeldTester is used. The MultiWeldTester is loaded with constant amplitudes for tension and torsion in plane and out of plane. The analysis of the hysteresis data of these tests leads to conclusions about the interactions on the fatigue behaviour.