Upcycling and Recycling Potential of Selected Lignocellulosic Waste Biomass

This research aimed to confirm the ability to reduce carbon dioxide emissions by novel composite production using plantation waste on the example of lignocellulosic particles of black chokeberry (Aronia melanocarpa (Michx.) Elliott) and raspberry (Rubus idaeus L.). Furthermore, to characterize the particles produced by re-milled particleboards made of the above-mentioned alternative raw materials in the light of further recycling. As part of the research, particleboards from wooden black chokeberry and raspberry were produced in laboratory conditions, and select mechanical and physical properties were examined. In addition, the characterization of raw materials (particles) on the different processing stages was determined, and the fraction share and shape of particles after re-milling of the produced panels was provided. The tests confirmed the possibility of producing particleboards from the raw materials used; however, in the case of boards with raspberry lignocellulose particles, their share cannot exceed 50% so as to comply with the European standards regarding bending strength criterion. In addition, the further utilization of chips made of re-milled panels can be limited due to the significantly different shape and fraction share of achieved particles.

An Equivalent Homogenization Theoretical Method for Composite Sandwich Cylinders Subjected to Pure Bending

An equivalent theoretical homogenization method was proposed for composite sandwich cylinders subjected to pure bending. Firstly, based on a homogeneous orthotropic layer hypothesis, the trapezoidal corrugated sandwich core was found to be equivalent in a homogenization orthotropic layer with the nine equivalent mechanical properties. Then, Lekhnitskii’s theory, based on a unified connection parameter method, was introduced and applied in the equivalent composite sandwich cylinder. The method developed by Lekhnitskii is suitable for arbitrary combinations of winding layers with different winding angles and materials. Additionally, the bending stiffness of the equivalent sandwich cylinder could be calculated. By developing user subroutine of UMAT, the numerical calculation results were in a good agreement with the results of the proposed method. Further, according to the Hill–Tsai strength criterion and the maximum strain criterion, parametric study was done for specified bending stiffness and specified bending strength. The results show that the influence of core parameters on the specified bending stiffness and strength are lower than that of the skin parameters. Additionally, larger skin thickness and smaller winding angles could improve the specified bending stiffness and specified bending strength of the composite corrugated sandwich cylinders.