Structural Design Optimization of CFRP Chopper Disks

The Institute of Lightweight Structures of the Faculty of Mechanical Engineering of the Technische Universität München has been designing and producing carbon fiber-reinforced polymer (CFRP) chopper disks for over a decade, specialising in designs for light disks with a high rotational speed. Chopper disks are commonly used in neutron “Time-of-Flight” spectroscopy. They are disks with one or more apertures rotating around an axis parallel to the neutron beam, reaching operational speeds of up to 22,000 rpm, correlating with accelerations of up to 200,000 g at the edge of the disk. Up to now, the disks have been produced using a quasi-isotropic laminate layup in an autoclave process. In order to achieve an increase in performance, three aspects have been investigated. First, a shape optimization of the apertures has been made, which directly impacts stress distribution. Second, the layup stacking sequence and orientation has been optimized regarding strength constraints. Finally the influence of the mass distribution on the dynamical behaviour of the disk has been studied. The mathematical basis of the optimization allows for the simultaneous consideration of stiffness, strength and mass constraint throughout the optimization process, leading to disks with an optimal mass and stiffness distribution. For a description of the detailed structural dynamic behaviour of the whole system, which comprises the disk itself, the collar, the shaft and the bearings, several numerical analyses have been carried out. Finally, dynamic tests have been performed, which are in accordance with the numerically determined natural frequencies.      «

The Institute of Lightweight Structures of the Faculty of Mechanical Engineering of the Technische Universität München has been designing and producing carbon fiber-reinforced polymer (CFRP) chopper disks for over a decade, specialising in designs for light disks with a high rotational speed. Chopper disks are commonly used in neutron “Time-of-Flight” spectroscopy. They are disks with one or more apertures rotating around an axis parallel to the neutron beam, reaching operational speeds of up to...     »