Due to the high specific strength and the very cost efficient manufacturing process by injection moulding, reinforced polymeric materials are more and more used in structural applications in automotive and other industries. Caused by the manufacturing process, reinforced polymers show a strong anisotropic material behaviour. To consider the lifetime of a part in an early state of a development process, it is indispensable to deal with all effects on the material from the manufacturing process to the real load history. A closed simulation chain is established to estimate the life time of a part based on local mechanical properties, depending on the fibre orientation from an injection moulding process. Other stress based influences like the mean stress or the stress peaks at notches are also covered. This work focus on how the fibre orientation and the formation of weld lines affects the mechanical properties of a short glass fibre reinforced polyamide. The fundamental basis for this work was a comparison of simulated fiber orientations in the specimens based on conventional flow simulation tools with computer tomography (CT) measurements. While CT-scans show a good correlation to the averaged fibre orientation in a simulation the core layer and the surface layer cannot be sufficiently predicted. The formation of weld lines also cannot be adequately assessed through the volume. Following this detailed morphological studies quasi-static and cyclic tests were performed on specimens with different fibre orientation as well as weld lines. The test results show a significant dependence of the mechanical properties depending on the fibre orientation. Moreover, weld lines lead to a significant decrease of the property profile. The results were used to set up a data profile to assess the lifetime of real parts using the established simulation chain.