Co-authors​ :

 Leon SCHRÖDER (GERMANY), Sebastian SPITZER (GERMANY), Michael SCHIFFNER (GERMANY), Maik GUDE (GERMANY) 

Fiber-reinforced polymer (FRP) structural components have the potential to achieve the highest circumferential speeds due to their high density-related mechanical properties such as strength and stiffness. These materials are exceptionally interesting for applications in rotating components, as future demands will necessitate achieving higher circumferential speeds and reducing rotating mass respectively moment of inertia to meet both technical and economic criteria. A robust shaft-hub connection is a prerequisite for functionality in hybrid designs, e.g. when novel FRP components are integrated into persisting metallic systems. In terms of lightweight design, interference fits (also known as press-fits) offer an attractive solution for connecting without additional fasteners or other connection elements that require significant design space. This reduces system mass and centrifugal forces at the same time which leads to lower energy consumption and less stress during operation. However, the use of hybrid interference fit connections in metal-FRP designs is challenging due to the anisotropic FRP material behavior, as existing computational approaches does not consider the anisotropic material behavior or require a high computational effort. Furthermore, the main problem at high circumferential speeds is the radial deformation of the outer part, leading to a reduction in the effective joint pressure, which can cause the outer part to slip and even lift off.

This paper presents an analytical approach to approximate the effective joint pressure in interference fits of metal-FRP joints, which can be used by engineers as a tool for efficiently estimating key design parameters such as laminate structure or wall thickness. Based on various assumptions about the structural behavior of the FRP component, a simplified model for the description of joints with anisotropic material behavior is developed using analytical models of press-fitted isotropic cylinders known from DIN 7190 for interference fits, among others. In particular, the presented calculation method makes it possible to calculate circumferential speed-dependent joint pressure curves with minimal computational effort, and to draw conclusions about the functionality or load transferability in a defined speed range by comparing them with the loads to be transferred. The accuracy of the analytical calculation approach is then checked against the results of numerical calculations. Practical design recommendations for metal-FRP interference fits with high circumferential speeds are derived based on a parameter variation. The paper thus contributes to the time and computationally efficient design of hybrid press-fit shaft-hub connections in metal-FRP designs, taking into account the deformation induced by centrifugal force during operation.