Analyzing Mechanical Property and the Corresponding Power Output of Bamboo Plant for the Construction of Vertical Axis Wind Turbine Blade

Abstract

Ethiopia has the largest bamboo plant coverage in Africa and has the third-largest wind power potential in Africa. These two factors inspired us to conduct this research. Use of Bamboo plant in Ethiopia is limited to a few common utilizations such as for furniture and civil construction. These applications resulted from less understanding of mechanical properties  of the plant. Hence, this study aimed to determine the mechanical properties of bamboo, particularly tensile and fatigue strength. Mechanical properties were analyzed on lowland (Oxytenantheria abyssinica) and highland (Yushania alpina) untreated bamboo. Tensile test specimens were prepared from both species, and the test was conducted with calibrated universal testing machines (UTM). The expected outcome was to decide whether or not bamboo plant mechanical properties qualify for the construction of small-scale wind turbine blades. A total of 30 tensile specimens were prepared to conduct the test. Fatigue stress was calculated using the relationship between the tensile stress as various literatures revealed that fatigue strength equals 40 % to 60 % of the tensile stress. Experimental test output shows that lowland bamboo tensile strength is 178.1 Mpa while the corresponding fatigue strength is 71.24 Mpa. For highland bamboo, the tensile and the fatigue stresses are 122 Mpa and 48.8 Mpa respectively. This result confirmed that lowland bamboo has better strength compared to highland bamboo. This is because lowland bamboo is denser in fiber or microstructure than highland bamboo. This ensures that lowland bamboo has a larger load-bearing capacity. Fatigue stress (cyclic load) is the predominant stress for the failure of a structure when an intermittent load is subjected to the specific structure even if the exerted stress is below the yield stress of the component. Findings ensured that the bamboo plant has adequate strength for the construction of small-scale wind turbine blade production. In Ethiopia, the estimated wind power potential is nearly one Gigawatt, and the installed capacity is only 404 MW. Small-scale wind turbine installation was not offered sufficient attention. Integrating these two potential resources (bamboo as raw material and wind resources) will enhance and contribute to small-scale energy production.

Keywords: Highland bamboo, Lowland bamboo, Fatigue Strength, Tensile Strength