Static and dynamic properties of CFRP rollers

Abstract

Carbon fiber rollers combine high axial stiffness with low weight. This leads to higher bending frequencies and increased critical speed and makes them suitable for high speed machines as web guide rollers or as other functional rollers. Due to the orthotropic properties of fiber composites static deformation as well as dynamic vibration modes of CFRP rollers differ significantly from those of metallic rollers. Improved performance of CFRP rollers compared to metal rollers is not only a result of the increased critical speed but is also coming from improved damping characteristics.

If CRFP tubes are optimized for axial stiffness and high bending frequencies, static and dynamic deformation that is negligible in metal rollers become significant due to their much lower shear modulus and circumferencial elastic modulus. These deformations have to be taken into account when designing a roller for high speed machines. FRP is a design material which allows to distinctively modify materials properties differently in different direction of the material. With the filament winding process the properties of fiber composites can be modified in a very efficient and versatile way. Additional design options can be used to decrease deformation.

Energy absorption in the resin matrix as well as in the fiber material contribute to the improved damping characteristics and can increase the damping factor of the dominant modal shapes by an order of magnitude.

Composite tubes having unique combination of static and dynamic properties have been produced by filament winding. Static and dynamic properties of these CFRP tubes have been investigated by Finite Element Methods and experimental Modal Analysis.

With the results of these analysis methods complete systems of multiple rollers interacting by nip contacts or through a web can be modeled and investigated. The goal is to derive design rules for rollers that help improving dynamic aspects of web handling.

Using optimized CFRP tubes considering all aspects of their static and dynamic properties rollers can be designed that show better performance in highly productive machines.