Multi-objective optimisation of cutting force and cutting power in chopping agricultural residues

Agricultural residues are the most abundant biomass and animal feed resources. Chopping is a prerequisite for either use, and reducing the shearing force has been considered as one of the most effective approaches to save energy. A smaller force can also permit more compact mechanical parts of the chopping device. In several cases, power consumption may be large even when the shearing force is small, if the corresponding cutting velocity is high. Consequently, it is important to minimise both cutting force and power consumption simultaneously. This paper presents an experimental study to solve such a multi-objective optimisation problem for chopping processes. Maize stalks with wet base moisture content of 81% were chosen as experimental samples. The response surface methodology (RSM) was used to design of experiments and evaluate the effect of cutting parameters, including approach angle, feed angle and cutting velocity, on the cutting force and consumption power. Compared to typical conditions in commercial choppers, where these angles are usually set to be 0°, the optimal setting can reduce cutting force and power consumption by 2.3 times and 4 times, respectively. The results are promising for practical applications in design and operation of chopping machines.