Experimental investigation, numerical modelling and model-based analysis of the frictional contact between natural materials and cutting blade

• Applicants: Professor Dr.-Ing. Markus Kästner; Professorin Dr. Anja Maria Wagemans
• Subject Area: Mechanics ; Biological Process Engineering ; Mechanical Process Engineering
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 420422342

Cutting of natural materials by means of blades is frequently used in the food industry. The method is applied to numerous products, including cheese slices or caramel sweets. Both the product quality and process stability significantly depend on process parameters such as cutting speed and temperature. A complex coupling of three dissipative mechanisms is inherent to blade cutting processes. These mechanisms are inelastic deformation, material separation, and friction between the blade and the natural material. While the first-mentioned aspects have been investigated in the completed project, the mechanisms and influencing parameters underlying friction are not yet understood. However, experiments suggest that up to 50 % of the work can be attributed to friction. Moreover, adhesion between cutting blade and natural material is decisive for the product quality. The completed project has focussed on the rate- and temperature-dependent ductile-brittle transition of toffee-like caramel. A phase-field model of rate-dependent fracture phenomena has been developed. With this model, it has been shown that the ductile-brittle transition results from the coupling of viscoplastic deformation behavior with a rate-dependent fracture resistance. As a consequence, depending on the speed or temperature, either massive inelastic deformation or brittle failure can be observed. The proposed project is intended to consistently continue the previous work. The aim is to thoroughly analyze the cutting process by means of continuum mechanics. In doing so, the proposal aims at for the first time taking into account the friction in between natural material and blade coupled with all other dissipative mechanisms. This will provide the basis for a physics-based optimization of production processes in order to achieve high-quality cut surfaces in a time- and energy-efficient manner. To this end, contact friction is analyzed experimentally, modelled using continuum mechanics and the existing phase-field model is enhanced so that frictional contact with fracture surfaces can be accounted for. In addition, the proposal aims at understanding the adhesion mechanisms underlying the macroscopically observed friction on small scales.

• DFG Programme: Research Grants