No abstract

The paper presents water absorption and its effect on the tensile properties of hybrid of fly ash-CaCO3-filled epoxy. The total filler content was 20wt%, with the fly ash to CaCO3 ratios were 20/0, 15/5, 10/10, 5/15 and 0/20. Adding fillers into epoxy decreased the water uptake in the ranges of 15 - 22%, where the lowest and the highest water uptake of the hybrid systems belonged to the fly ash/CaCO3 ratios of 15/5 and 20/0, respectively. The tensile strength and elastic modulus continued to decrease with aging time for all epoxy systems. At the saturation level, the tensile strength and elastic modulus of filled epoxies were improved compared to the unfilled epoxy, except for the hybrid of fly ash/CaCO3 of 15/5. The fracture strain as well as the tensile toughness were considerably increased at the equilibrium. A scanning electron microscopy revealed that in dry condition the fly ash was well bonded with the matrix, but not for the CaCO3 particles. In the semi equilibrium and equilibrium states, the fly ash and CaCO3 were mostly detached from the epoxy. The hybrid of fly ash/CaCO3 of 15/5 was not recommended as it decreased the tensile properties more than the other hybrid compositions.

In some areas in Indonesia, such as: the southern part of Sumatra until Nusa Tenggara, wind velocity is large enough to be used as a wind power plant with a range of 5-15 knots of wind speed equivalent 2.5-7.5 m / s. However, wind energy has not yet been developed, there are only a wind power plant with a total capacity of 1.4 GW in Indonesia. Mostly, instruments wind power is basically intended for European plains wind speed range of 10-30 knots. So that the necessary adjustments for the Indonesian state that smaller wind speed in order to optimize the system work.The purpose of this study was to determine the influence of the number of blades and wind speed on electric power generated by a horizontal axis wind turbine. The type of blade used is arched plate and fitted with a pitch angle of 30o. Key issues to be examined in this study is how the influence of the number of blades (3, 4, and 5 blade) and wind speed (3m / s, 4m / s and 5 m / s) to the performance of horizontal axis wind turbines.These results indicate that the number of blade 5 gives rpm, torque, power and highest Cp compared to the number of blade 3 and 4. Similarly, the wind speed of 5m / s provide better performance on any number of blade.

The objective of this research is to obtain the bending  properties  of  composite  material  produced  by VARI method, and to get analysis of polyester resin distribution time on the layer of fiberglass  composite and bamboo woven strip.The process of making composites varies, but the process of making this research is the process of Vacuum Assisted Resin Infusion (VARI). In the VARI process, dry fiber is placed between the fixmold and plactic bag, then the  resin  is injected  after  the chamber  inside the  low- pressure plastic bag and the process continues until all parts of the fiber are wetted by the resin.From the results of research, testing and discussion of bending test results that have been done then can be drawn conclusions include: Variation of the number of reinforcement layer on VARI method will affect the value of bending strength of composite. By using the VARI  method  The  highest  average  value  of  bending stress  occurs  in  variation  4  (206,69  MPa),  while  the lowest occurs in variation 1 (42,83 MPa), and the time required for the distribution of resin varies in time variation 1 which takes 5 minutes 02 seconds, while for variation 4 takes 8 minutes 3 seconds.Keywords: composites, VARI method, glass fiber, bending test

No abstract