For centuries, concrete is the main material most widely used in a building. The strength and durability of this material will decrease over time due to several factors that influence the mechanism of its structural characteristics. Although the compression strength is excellent, it is weak in tensile. Fiber reinforced polymer (FRP) composites are widely used as an alternative material to replace metal-based engineering materials. This material has properties such as lightweight products, low production costs, easy to form, high tensile and flexural strength, and elastic. The purpose of this review paper is to provide information about the application of FRP composites as reinforcement of concrete structures either as repairs or new structures. Initially, FRP composite materials were used as reinforcement structures for reinforced concrete column-beam joints. The resulting structure has increased the flexural ability due to the load given. The addition of natural fiber (jute) to concrete also increases in the hardness of concrete. Other investigations regarding the application of FRP composites in concrete to improve strength performance are discussed in this paper. Finally, the technique of wrapping FRP composites in concrete in an effort to improve the performance of the resulting structure is also discussed in the paper.

A skateboard is a small piece of wood shaped like a surfboard with four wheels attached to it that is used to glide on a certain track. In general, this tool is made using wood material taken from nature and vulnerable to environmental damage issues. In this research, the waste of banana stems will be processed into the main raw material for skateboarding. The type of material chosen is the type of composite material with banana stem waste selected as reinforcement and polyester resin as the matrix material. The purpose of this research is to design and manufacture a skateboard made of composite fiber reinforced banana stem fibers and to test its flexural strength to obtain the characteristics of the material formed. The design was carried out with the help of the 2007 version of Autocad software by following commercial skateboard standards.  Flexural testing was carried out at the Impact and Fracture Research Center laboratory, Faculty of Engineering, University of North Sumatra. Static static testing of polymer composite board specimens from banana stems obtained the average value data for the composition of 5% banana stems is 9.81 MPa, for the composition of 10% banana stems an average of 13.60 MPa, and composition of 15% banana stems the average is 27.20 MPa. 2. The analysis shows that the best composition is 15% of banana stems, with an average flexural strength value of 27.20 MPa. Therefore, the composition used in this study is the composition of 15% reinforcement of banana stems.

Polymeric composite foam with EFB fiber reinforced is new material that can be utilized as an alternative engineering material. EFB fiber utilization becomes the center of subject in this research. Moreover, these composites are unique with the presence of cavities (foam) in the matrix of unsaturated polyester resin. It results a decrease in density of the material that formed, and obtain a thermoset polymer composite material lighter than any else similar type. The objective of this study is to obtain the best manufacturing techniques of composite material, the mechanical behavior of these materials due to tensile static loading and high strain rate impact, and the distribution of foam that occur in the material that formed as a result of blowing agent (BA) from the type of polyurethane (PU). In this research, the sample formed into standard specimen of testing, such as ASTM D638 for static tensile test, and impact test specimen. Mechanical’s behaviors that are obtained in this research are density, tensile strength, modulus of elasticity (E), the incident stress, and dynamic modulus of elasticity of the material. For static testing was performed according to standard ASTM D638 tensile and impact test using the Kolsky’s method. To know the distribution of foam that occur in the material, were observed using Scanning Electron Microscope instrument (SEM). To determine the stress distribution in this material, then conducted a computer simulation using Ansys. The best result obtained by the composition of this material based on material composition, which resin consumption can be reduced by the presence of BA as well as mechanical strength, good enough for molding. The best composition in this study will be used in subsequent studies, namely the design and manufacture of traffic cones from this material.

<em>Typical technology for processing red onion affects the quality of red onion produced. The process of drying red onion is one of the important factors in producing the best quality of red onion. Environmentally friendly and easy operation and maintenance technology is the desired technology. In the process of engine design, the strength of the material and structure are the main factors of the building of the machine. Calculation with finite element method (FEM) is the best choice to obtain information on stress distribution on a machine structure. In this study, the calculation of the FEM method was assisted by Ansys APDL 15.0 software. The objectives of this study were: (1) calculation of the load on the tray structure, (2) the distribution of stress on the tray structure, seat, and frame for red onion dryers, and (3) analyzing the strength of the material using the Tresca and Energy Distortion methods. The input load comes from the weight of the tray and red onion. The analytical method used is the finite element method with the type of structural analysis and Beam 3Node 189 element type. Based on the FEM simulation results, the maximum stress that occurs in the tray is 1.22 MPa and the maximum deflection is 0.0055 mm. The maximum stress in the tray support structure is 33.25 MPa and the maximum deflection is 0.014 mm. The maximum stress on the frame structure of the onion drying machine is 0.89 MPa and the maximum deflection is 0.000235 mm which occurs in the middle of the machine structure. Using the Tresca and Distortion Energy theories, it is found that the stresses that occur are still far from the failure criteria for all structures. Likewise, the deflection that occurs is very small so that the construction of the onion drying machine is safe to use.</em>