Analysis of Number of Layers and Volume Fraction of Fiber Against Shock Load and Composite Compressive Strength Wind Turbine Propeller

The manufacture of wind turbine blades has a very high risk of failure, especially in the manufacturing section or in this case the material structure. If the structure of the propeller material is not able to withstand the very high pressure and air flow, it will result in the failure of the material structure when it is in use. For this reason, the purpose of this study was to determine the composition of composite materials that have high strength and toughness properties and are suitable for wind turbine propellers. The method used in this research is experimental. The independent variables include the number of layers and the volume fraction of straw fiber. The dependent variables are shock load and compressive strength. Each compression test specimen is made with a gauge length of 100mm, a width of 25mm, and a thickness of 2.5mm. While the impact test specimens are made equal to l25mm long, l2mm wide, l2mm high, and 2mm notch. The results showed that the bending strength of the straw fiber composite with 6 layers had an increasing trend as the number of layers increased. The highest bending strength with the number of piles of 6 layers and the lowest strength with the number of piles of 2 layers. In addition, the volume fraction is very influential on the bending stress of the straw composite matrix. It can be seen that the matrix with a volume fraction of 50% has the greatest bending stress in each number of layers, both 2, 4 and 6. For the impact test, it is found that the optimal number of layers occurs in the number of 2 layers with a volume fraction of 33%. The shock load tends to decrease. Meanwhile, based on the volume fraction, the larger the volume fraction, the smaller the shock load that can be received by the straw fiber composite material.

Effect of Rotten Butter Shock Load on Anaerobic Digestion of Chicken Manure

Anaerobic digestion is a popular method for improving fertilizing properties, but there is no report on the effect of shock load with butter on anaerobic digestion of chicken manure. Therefore, this study aimed to investigate the anaerobic digestion of chicken manure with butter addition. The volatile suspended solid (VSS) was set at 20g VSS/L with different butter additions from 0 to 60 g VSS/L and different oxygen flow rate (OFR) from 0 to 2.5 mL/h. The results showed that ammonia ranged from 0.072 g/L to 0.082 g/L, while the volatile acids ranged from 425 mg/L to 325 mg/L. The volatile organic acid was significantly influenced by a change in OFR compared to ammonia, while a correlation between hydrogen and hydrogen sulfide was observed. The results showed that the highest hydrogen and methane production was obtained at butter addition of 30 g VSS/L with OFR 1.4 mL/h with volumes of 78 mL and 25 L respectively. In addition, hydrogen sulfide emissions induced rapid growth with increase in butter concentration.

Behaviour of a Cylindrical Reinforced Carbon Fibre Shell Under Impact Load

This work is devoted to numerical analysis of the behaviour of reinforced cylindrical shell made of a polymer composite material (PCM) under the action of an unsteady shock load, taking into account interlayer defects of elliptical shape, as well as evaluate the strength of composite package and the development of delaminations.

DYNAMIC BEHAVIOR OF REINFORCED CONCRETE COLUMN UNDER ACCIDENTAL IMPACT

The analysis of scientific literature shows that to date, the physical parameters of the deformation of reinforced concrete bar structures during their dynamic buckling and the influence of the dissipative properties of the structural system on this process remain insufficiently studied. In this regard, the paper proposes an analytical solution to the problem of dynamic buckling of a reinforced concrete column when it is loaded with an impact load, taking into account the presence of initial geometric and (or) physical imperfections and damping properties of the system, as well as an analysis and assessment of the column deformationparameters based on the obtained analytical solution. An expression for the dynamic deflection of a bar element under its axial loading with a high-speed shock load, taking into account damping, is obtained in an analytical form. For practical calculations in a quasi-static formulation, the paper proposes an expression for the dynamic factor kd of bar structures under axial shock load. A numerical example of calculating a reinforced concrete column using the obtained analytical expressions with and without damping is considered. It was found that the maximum deflection of the elastic axis of the column under high-speed loading was achieved at t = 0.04 s. In this case, the total dynamic deflection taking into account damping was 4.8% less than the deviation without taking into account damping and 1.18 times more than the corresponding static value.

Implementation of marble waste as aggregate material rigid pavement

The rigid pavement is used for the pavement with soft ground conditions (subgrade). On the other hand, in recent years, marble waste for civil construction has been widely used to substitute conventional materials such as fine and coarse aggregate in concrete. This study aims to optimize marble sand waste as a substitute for river sand aggregates on concrete pavements. This research creates innovation in the production of rigid pavement. The study used an experimental method to test the raw material, namely fine aggregate (river sand and marble sand) and rigid pavement testing, with various variations in the material's composition, including loading, strain, and concrete slab stress tests. The use of marble sand as a substitute for river sand affects the compressive strength of concrete. The maximum compressive strength of 34.67 N/mm² occurs at 60 % marble sand content. Calculation of the optimum level of marble sand by the regression method yielded 48.90 % with an average compressive strength of 32.37 N/mm². In terms of strain, rigid pavement concrete slabs with 60 % marble sand content showed the best performance among all specimens. The stretch is relatively small so that it is not so fluctuating, the flexibility is relatively small, and the stiffness is the highest. The strain character tends to be compressive so that the dependence on reinforcement will decrease. Dynamically at the shock load, the three concrete slabs are quite good and very far from resonance in both the traffic service load frequency and the large shock load. Rigid pavement concrete slabs with a marble sand content of 40 % show the best performance because they are damping faster and have less tension. Statically, rigid pavement concrete slabs with a marble sand content of 60 % are the best

Performance of a constructed floating wetland in mesocosm scale: nutrient removal under shock load and water level oscillation

<p>Constructed Floating Wetland (CFW) has shown a high capacity to transform, recycle, retain and remove different types of pollutants, especially nutrients. A CFW was developed in mesocosms at the Institute of Hydraulic Research at the Federal University of Rio Grande do Sul, Brazil, in order to evaluate the functionality of the system on treating synthetic effluent with nutrient concentrations simulating urban surface runoff. Two species of emergent macrophytes, <em>Typha domingensis Pers.</em> and <em>Schoenoplectus californicus </em> were employed. The CFW was evaluated under changes in nutrient concentration and water level during two subsequent experiments, identified as “shock load” in order to simulate extreme rain events, accidental spills of pollutants or illegal discharges that are common in drainage systems and urban rivers worldwide. Comparative evaluations between species and the system responses were evaluated in different hydraulic retention time (HRT). The system was exposed to 24 h of HRT, with 20 cm of water level and 1.8 mg/L of TP, 4.9 mg/L of TN (mean concentration). After sampling, the tanks were filled to 40 cm, with 3.0 mg/L of TP and 13.8 mg/L of TN concentration . Samples were collected within 2 and 4 h to quantify the system's response to shock-load. After sampling, the level was reduced to 20 cm, followed by exposure for the remaining 6 days, when final samples were collected. Temperature, conductivity, dissolved oxygen and redox potential were measured <em>in situ</em>. Turbidity, color and pH was measured immediately after collection in the laboratory. Total phosphorus (TP), orthophosphate (PO<sub>4</sub><sup>3-</sup>), total nitrogen (TN), total organic carbon (TOC), chlorophyll-a and pheophytin were also quantified. Only orthophosphate presented significant differences between initial and final concentrations, after the first 24h (<em>F = </em>6.106<em>, df = </em>1<em>, p = </em>0.024). The shock load demonstrated significant differences between initial and final concentrations for TN (<em>F = </em>10.097<em>, df = </em>1<em>, p = </em>0.005), for TP (<em>F = </em>9.392<em>, df = </em>1<em>, p = </em>0.0067) and for TOC (<em>F = </em>9.817<em>, df  = </em>1<em>, p = </em>0.005). As to final batch, significant differences between input shock load and output values were found for TN (<em>F = </em>103.45<em>, df = </em>1<em>, p < </em>0.001), for TP (<em>F = </em>7.584<em>, df = </em>1<em>, p = </em>0.0067), for PO<sub>4</sub><sup>3-</sup> (<em>F = </em>6.864<em>, df = </em>1<em>, p = </em>0.017) and for TOC (<em>F = </em>73.608<em>, df = </em>1<em>, p < 0.001</em>). After 6 days, average removal rates for TN were about 28% for <em>S. californicus</em> and 87% for <em>T. domingensis</em>, for TP such removals were 29% and 55%, respectively. <em>T. domingensis</em> superior root development in association with the biofilm in the rhizosphere of the plants, were responsible for the best efficiency. The results show evidence of the benefits related to the ecosystem service associated with the CFW built in mesocosms. The understanding of the performance of compensatory techniques in controlled situations represents an indispensable tool for the knowledge of the limitations and the consequent technical improvement necessary for the feasibility of implementing nature-based solutions as the CFW. </p>