2025, Walczak, Natalia, Walczak, Zbigniew

As a result of the energy crisis due, among other things, to climate change, most developed countries have taken steps with the main aim—among other things—of increasing the use of green energy sources that do not rely on fuels (including primarily liquid fuels) but use renewable energies. Plant biomass is a versatile substrate that can be used in many areas of the economy and production, but also for the production of various types of fuel. These range from rapeseed oil used as a component of biodiesel or maize starch for ethanol production to typically cellulosic plants such as energy willow, which can be used for direct combustion. The floodplain is home to this type of vegetation. It is characterized by great diversity in terms of geometric dimensions and mechanical and morphological properties. In addition, the location (easy access to water and sunlight) influences its potential energy value. Vegetation, thanks to favorable conditions, can achieve large weight gains in a relatively short period of time. Therefore, its properties should be carefully recognized in order to make more efficient use of energy and operating equipment used during harvesting. This paper presents an analysis of the changes in the elasticity of willow branches over a period of 16 days following harvesting. The changes were analyzed for branches taken from three different shrubs at three different plant height levels during the post-growth period. Based on the measurements carried out, the elastic modulus E of the shoots was estimated. The average modulus of elasticity ranged from about 4500 two days after cutting to about 5500 MPa 16 days after cutting and showed high variability, reaching even CV = 37%, both within a given shrub and depending on the measurement date. The results presented here indicate a high natural variability of mechanical parameters even within the same plant.

2022, Walczak, Natalia, Walczak, Zbigniew, Ficner, Tomasz

Floodplain vegetation is characterized by its ability to resist deformation and destruction and to deform elastically and plastically under the influence of external mechanical forces. The force of water that presses on the plant induces stress and deformation in it, but once the force is removed, the elastic properties of the vegetation return it to its original state. It regains its original size, shape, and volume. In this paper, the deflection arrow was analysed based on the field tests conducted, and then the modulus of elasticity of natural shrub vegetation was determined. Measurements were made at different plant heights. Analysis was carried out at different growing periods to estimate the variation of plant elasticity with growth, development, and season. The results confirm the loss of flexibility during winter for all the shrubs analysed. Based on the measurements carried out, the elastic modulus E of the shoots was estimated. The average modulus of elasticity ranged from about 2100 to about 4000 MPa and showed high variability, reaching even µ = 50%, both within a given shrub and depending on the measurement season. The results presented here indicate a high natural variability of mechanical parameters even within the same plant.