ANALYSIS OF NON-DESTRUCTIVE TESTING IN THE METAL STITCHING PROCESS

This research addresses damage and cracks in the Yanmar 6N18L – EV engine block through metal stitching, a coldwelding method using pins and locks to prevent thermal and mechanical cracks. The study aims to assess crack quality post metal stitching via NDT Liquid Penetrant and hardness through NDT Hardness Testing. Economic value is also evaluated. Data is collected through field observation and experimentation, meeting ASTM 159 G3500 standards. Results indicate successful crack repair, meeting NDT Liquid Penetrant standards, and achieving a 230.6 HB average hardness with a 4.82% variance, aligning with ASTM 159 G3500's 207-255 HB range. Economically, metal stitching proves beneficial with an NPW of Rp 412,353,912, making it a preferred solution for engine block crack issues

UTILIZATION Of Sn-Sb-S AS A NEW MATERIAL SENSITIZED SOLAR CELLS

In this research process to observe the utilization of Sn-Sb-S for new material solar cells. With the SILAR (successive ionic layer adsorption and reaction) method, it was found that good conditions for growing quantum dots on the surface of TiO2 were 8 turns to get Sn-S and 6 turns for SbS and heated at 325 0C for 12 minutes. As for tools to analyze Sn-Sb-S there are quantum dots by observing using XRD and the size of quantum dots. UV Visible is used to observe the gap energy of 1.63 eV which includes a wavelength of 300-850 nm. The use of SEM to observe the morphological characteristics of Sn-Sb-S on the surface of TiO2 obtained the size of quantum dots ~ 16.6 nm. The best sample with ZnSe passivation layer resulted in short circuit current density Jsc of 14.04 mA/cm2 open circuit voltage Voc of 0.46 V, fill factor FF of 39.91%, and power conversion efficiency η of 2.58% under 1 sun.  Keywords: quantum dots, science materials, renewable energ

OPTIMIZATION OF MOUNTAIN BIKE FRAME DESIGN: LOADING VARIATIONS USING HIGH STRENGTH CARBON

Mountain bikes have become a popular mode of transportation and recreation among extreme sports enthusiasts. A strong and lightweight frame design is crucial to support performance and ensure rider safety, especially in challenging terrain conditions. This study aims to explore the optimization of mountain bike frame design with a focus on the use of high-strength carbon materials. The research evaluates the performance and durability of the frame through Von Mises stress analysis, displacement, and safety factor under load variations of 65 kg, 70 kg, and 75 kg. The analysis results show that the stress increases with the load, from 7.298 MPa at 65 kg to 8.421 MPa at 75 kg. Displacement also increases, from 0.004982 mm to 0.005748 mm. The safety factor remains above 15, indicating a high safety margin for the material. These findings suggest that although stress and deformation increase, the frame design still meets the strength standards required for user safety. This research contributes significantly to the development of more efficient, sustainable bicycles, and serves as a reference for manufacturers in designing safe and comfortable products. Recommendations for further testing include dynamic load analysis to understand the frame's behavior under real-world usage conditions. Keywords: AL 6061, Mountain Bike Frame, Simulatio

OPTIMIZATION AND PREDICTION OF CENTRAL AC SYSTEM PERFORMANCE WITH RESPONSE SURFACE METHODOLOGY (RSM) MODELING

Optimizing AC system performance is important to optimize energy consumption, especially at partial load. The aim of this research is to obtain a performance model of the central AC system based on its operational conditions which include environmental air conditions, heat load conditions and other operational parameters, so that the performance of the AC system can be optimized which includes cooling capacity, power consumption and energy efficiency ratio. Data is obtained by experiment, then analyzed by Response Surface Methodology (RSM) to obtain optimal system performance. This research resulted in models of AC performance with coefficient of correlation (R2) of 0.9745, 0.2041 and 0.8965 for cooling capacity, power consumption and EER respectively. By analysis of varians for models, it is obtained that Model F-values are 9920.83, 313.45, and 2245.59 for cooling capacity, power and EER respectively, and implied that the models are significant. The Adequate precision ratios were 1078.33, 93.08, and 344.32 for those parameters respectively, and indicated the adequate signals. The optimum results obtained were a cooling capacity of 46.7 kW, compressor power consumption of 4.48 kW, and an energy efficiency ratio of 8.5. Keywords: Performance; Central air conditioning; Prediction; Optimization; RSM

EFFECT OF WELDING SEQUENCE ON DISTORTION RESULTS IN BRACKET CONNECTIONS

The distortion in the shape of the weld specimen is influenced by the uneven heat distribution during the welding process. There is also distortion in the welding modeling performed on the bracket joint. The modeling scenario of the bracket joint forms the basis for measuring the distortion results. Therefore, when we model the bracket joint, we obtain varying distortion results. There are three lines to observe the distortion effects. Lines a, b, and c are located on the X and Y axes (center), while line c is on the X and Y axes (+). Line a is on the X and Y axes (-). The test specimen that has been modeled is the result of numerical modeling, which is then used to calculate the magnitude of the distortion on the longitudinally stiffened plate test specimen. For the numerical modeling of the bracket joint, the result of scenario 1 is distortion. Meanwhile, the distortion results of the bracket joint modeling in scenarios 1 and 2 show that the distortion value obtained in scenario 2 is higher than that obtained in scenario 1. This is influenced by the order of welding lines used in the bracket joint modeling

ANALYSIS OF CAVITATION LEVEL IN WADASLINTANG HYDROPOWER PLANT USING THOMA CAVITATION FACTOR

Turbine damage can be caused by several causes, including damage to the turbine due to cavitation on the surface of its blades. Miscalculation of the position or location of the turbine can occur and will result in this cavitation. The Thoma cavitation factor is used to determine whether the turbine operation is safe from cavitation. This research was conducted at the Wadaslintang Hydroelectric Power Plant. The research used a quantitative descriptive research method. This study aims to determine the level of cavitation that occurs in the Francis turbine at an actual reservoir elevation of 169.23 meters above sea level with maximum guide vane openings to minimum guide vane openings. At variations in guide vane openings of 100% and 80% cavitation occurs, while at guide vane openings of 76%, 60%, 40%, and 20% cavitation does not occur. The larger the guide vane opening, the cavitation level is in a more dangerous condition because the difference between the cavitation factor and the critical cavitation factor is smaller, with the difference values ​​of 1.285073, 1.023435, 0.970782, 0.763080, 0.506127, and 0.253081, respectively. The smaller the guide vane opening, the smaller the risk of cavitation, but the power generated is also smaller. Safe operating conditions from cavitation with the greatest power are found at a guide vane opening of 76%-80%. Keywords: francis turbine, guide vane, cavitation, thoma cavitation factor

DESIGN OF A 100 KG CAPACITY WORKING LIFT CART FOR SMALL-SCALE INDUSTRIAL APPLICATIONS

To accommodate heavy tool movement, forklifts are commonly used. However, a forklift is too large for use in confined workspaces within small industries. Therefore, it is proposed that a 'Working Lift Cart' be designed with a compact size. This research aims to design and develop a compact lift cart that offers flexible movement and reduces operational risks compared to existing forklift products. The method employed in this research involves a direct analysis of two proposed product plan concepts. The proposed concepts are selected based on a needs analysis. The chosen concept undergoes a safety risk analysis from the operator's perspective using the RULA method, while the product design is subjected to static stress analysis on the frame and the lifter. The results indicate that the second concept, with greater operational flexibility, is chosen. The RULA analysis, conducted using CATIA software, indicates that operating with a remote controller is significantly safer and less prone to injury. However, manual operation is retained for usability purposes. The analysis of the frame structure and lifter shows that the proposed design is safe for a 100 kg load on the lifter.  Keywords: Working Lift Cart, Design, RULA, Static Stress Analysi

IMPACT OF NANOPARTICLES AS A HOMOGENEOUS CATALYST IN IGNITION CHARACTERISTICS OF WASTE PLASTIC OIL

A novel approach was employed to develop alternative fuels by blending pyro-oil from used plastic with graphene, which acted as a combustion additive. The biofuels were produced through pyrolysis of high-density polyethylene (HDPE). When evaluating the fuel blends, the fuel properties were analyzed and compared to commercially available diesel fuel, while Fourier transform infrared (FTIR) spectrometry was employed to know the fuel character. The findings demonstrate that including graphene as a combustion additive significantly enhances the Fuel's performance. The phenomena suggest that graphene effectively weakens the dispersion forces among the triglyceride molecules. Consequently, the droplet is easier to burn. By incorporating graphene, the alternative fuels droplet exhibits improved ignition properties, offering potential benefits in terms of efficiency and performance. The additive plays a crucial part in modifying the molecular structure of the Fuel, resulting in enhanced reactivity and ignition characteristics. Furthermore, the analysis of physical properties and spectroscopic data provides valuable insights into alternative fuels' molecular composition and behavior

THE EFFECT OF ENGINE NOISE ON CADETS AT THE INDONESIAN AVIATION ACADEMY VOCATIONAL SCHOOL BANYUWANGI

Noise is a sound that causes sound violence and disturbs humans. In the aviation industry, noise affects flight safety and success because it can interfere with the concentration and performance of flight cadets. In addition, high intensity can also cause stress and fatigue in flight cadets, reducing their ability to maintain focus and respond to critical situations. This study aimed to analyze the impact of noise produced by engine sounds and radio signals on pilots. The results of this study on the aircraft dashbord sound noise value is greater because the aircraft dashbord clan is located adjacent to the engine while the smallest noise value is found in data retrieval in the back seat because it is farther from the engine. The data collection carried out produces output in the form of data resulting from the effect of engine noise on cadets. Keywords: noise,cadets,engine soun

THE ANALYSIS THERMAL CONDUCTIVITY OF PINEAPPLE FIBER COMPOSITES EPOXY AND NA2SIO3 AS CAR LIGHT SOCKET MATERIALS

Along with the increasing number of motorized vehicles and the massive renewal of it, their lifetime has become faster, especially for cars. The problem often occurs in cars that have passed their lifetime is a lighting system, one of which is that the car's light socket often melts. Car headlight sockets made of plastic and rubber which function as seals cause the socket to melt when exposed to heat. Based on the existing problems, the purpose of this research is to find new material for making car light sockets using the standard hot wire method. The production begins with mixing epoxy resin with hardener using the hand lay-up method with a ratio of 2:1. Stir mixture for 5 minutes and add the pineapple into molds (110x60x20) mm and wait for a day at room temperature. Furthermore, the thermal conductivity test using QTM-500 tester. Based on the research results, all specimens suitable for the requirements use as materials for making car light sockets, because the thermal conductivity values of all specimens (0.2231, 0.2061, 0.2249) W/mK were below the thermal conductivity values of the previous socket-making materials, 0.23 W/mK. The best specimen composition is specimen 1 with thermal conductivity value of 0.2231 W/mK. This is because specimen 1 has little porosity or voids and small conductivity value. Thus, the composition ratio that is best used in the manufacture of car light sockets based on the total mass of resin, hardener, pineapple fiber, and sodium silica is 15: 7.5: 1: 3.75. Keywords: composite, pineapple fiber, thermal conductivity, socket, catalyst &nbsp