ADVANCED DESIGN OF SCREW JOINTS WITH TRANSVERSE LOADING AND LIGHT MATERIALS

Since long years threaded fastening systems are established all over the world and they will be of importance also in the future; general design rules are well known like VDI 2230 [14]. Today new materials [1] and numeric simulation tools lead to more detailed results and to significant improvements the design of an optimized screw joint for tomorrow looks largely different compared to a traditional bolted joint calculation. Focusing transverse loads especially shape based joint design is suitable for highest loading capacity. Due to this it is necessary to investigate the local stressing and the behavior when loaded in such joints more in detail. The behavior is characterized by the elasticity of the materials of clamped components (e.g. steel or light metals), the resilience of the clamped parts as well as by the clearance between the clamped parts themselves. As a reference situation a typical geometry was modeled with bracket, pull rod and screw/bolt. Based on this the investigation focuses on the main influences on positive force transmission and proposes an approach for advanced design of the loading capacity. Important aspects are the consideration of more-dimensional stress state during loading and the evaluation of important design parameters for geometry variations. New products are using more and more light materials [1] which exhibit an increased sensitivity due to force transmission in component contact zones. This paper gives an overview about related criteria when designing fastened component systems with transverse loading. Numeric stress analysis with FEA calculates a detailed stress distribution with significant inhomogeneities. Finally, conclusions for future engineering design are drawn.