Fatigue design of thermoplastic laser welds
At the present time, the amount of polymers used for lightweight design applications is increasing steadily. In the past, components made from polymers have often been designed using conventional structural design concepts. These concepts do not scope all of the potential benefits of the material which could be used for lightweight design. A new technology for the joining of polymers used for lightweight structures is the laser welding process. For structures joined using this new technology, the specific values of mechanical properties of the polymer weld lines, which are essential for lifetime estimation, are often missing. In most instances, the requirement is for laser welded structural components to be hermetically sealed. Therefore, inner pressure testing is an allocated test scenario. Test specimens that can be used to represent specific inner pressure load scenarios are only partially available. This paper presents a new type of test specimen for inner pressure loading at the laser weld line. Based on experiments, S/N-curves for inner pressure loading and different laser weld process applications have been established.