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Topology optimization has demonstrated its effectiveness in generating lightweight and structurally efficient designs. This study focuses on refining the geometry of an automatic coupler body for trains using solid isotropic material with penalization and a level set method. These optimization methods are applied to the numerical model of the automatic coupler, and their results are compared to select the optimal design. The tensile strength of the automatic coupler is examined through numerical simulations and validated by experimental tensile tests conducted on a 1:1 scale prototype. The optimization outcomes reveal a remarkable 46.41% reduction in the mass of the automatic coupler body compared to the initial model. An evaluation of the tensile strength of the prototype demonstrates the ability of the automatic coupler to withstand the primary load without undergoing plastic deformation. Furthermore, a strong correlation is observed between the numerical and experimental results. This research contributes to advancing the design of next-generation automatic couplers, emphasizing the crucial aspects of lightweight design and structural performance.

Gears with the involute profile are assumed to be rigid and good at producing mating gear. They are also deformable and deflectable, indicating additional space is required to avoid interference from the unpredictable shaft, misalignment, and dynamic factors. In addition, load and rotational speed cause frequent mild to severe interference leading to a significant reduction in its lifespan. This study conducted an experimental comparison between standard and modification involute gear profiles in a ratio of 1:2 to reduce interference. It was carried out using 18 pinion teeth with a 72 mm base diameter at three and four levels of torque load and speed. The load was also mounted a strain gauge on pinion gears to conduct strain measurement on the gear leg. Finally, it was applied using a mechanical brake measured by a dynamic torque meter. The experimental test obtained microstrain when the modified spur gear contacted for 3.04 – 6.67 milliseconds depending on the rotation speed and torque load. Modification of the linear involute profile significantly reduced the tooth leg strain at the rate of 5.6% to 13.99%. Meanwhile, the maximum microstrain reduction of 13.99% occurred at a speed of 1100 rpm and a torque load of 65%.

AA6061-T651 material joints produced by friction stir welding (FSW) were analysed in this study. The analysis was conducted to determine the effect of the concave shoulder angle (CSA) of the tool on mechanical and fractographic properties. The mechanical properties studied included impact strength (IS) and hardness (HS), while the fractography included impact fracture and microstructure. The experiments used a Taguchi L16 (44) orthogonal array and were done thrice. The best parameters were then used four times for confirmation. The research findings confirmed that the change in CSA significantly impacts the IS of welded joints. Combining both artificial neural network (ANN) and genetic algorithm (GA), it was found that 9° is the best CSA for IS. The mechanical properties test results showed an IS of 0.806 J/mm2. The HS of the weld nugget zone (WNZ) decreased by 25.49 % compared to the parent material zone (PMZ). This decrease in HS is due to the phase change of magnesium silicide (Mg2Si), resulting in finer grains in the WNZ than in the PMZ. Meanwhile, the fracture angle of the impact test specimens was 81.7°, indicating moderate toughness characteristics.

Seiring perkembangan zaman, teknologi roda gigi dituntut untuk mampu mentransmisikan daya yang besar dengan efisiensi yang besar pula. Pada jenis intersecting shaft gear, tipe roda gigi payung spiral (spiral bevel gear) merupakan perkembangan dari roda gigi payung bergigi lurus (straight bevel gear). Kelebihan dari spiral bevel gear antara lain adalah kemampuan transmisi daya dan efisiensi yang lebih besar pada geometri yang sama serta tidak terlalu berisik. Akan tetapi spiral bevel gear juga mempunyai kelemahan jika dibandingkan dengan straight bevel gear. Selain proses manufaktur yang lebih rumit, profil lengkung gigi spiral ini membuat distribusi tegangan yang terjadi menjadi lebih rumit untuk dimodelkan dengan persamaan matematika. Salah satu pendekatan yang dapat dilakukan adalah dengan menggunakan metode elemen hingga. Penelitian diawali dengan membuat model dari straight bevel gear dan juga spiral bevel gear yang sudut spiralnya divariasikan 20, 35, dan 45 derajat. Model dibuat dengan dimensi yang sama baik diameter maupun jumlah gigi gear. Langkah selanjutnya yaitu perhitungan analitis pada straight bevel gear dimana hasilnya akan dibandingkan dengan hasil simulasi statis. Setelah eror yang terjadi dibawah 15% maka dilakukan simulasi dinamis pada semua model yang telah dibuat yaitu straight bevel dan juga spira bevel gear. Hasil yang didapatkan dari penelitian ini adalah secara keseluruhan spiral bevel gear lebih kuat daripada straight bevel gear pada dimensi dan beban yang sama jika dilihat dari lebih kecilnya tegangan bending dan tegangan kontak maksimum yang terjadi. Tegangan terbesar terjadi pada jenis straight bevel gear baik pada tegangan bending maupun tegangan kontak sedangkan spiral bevel gear dengan variasi sudut Seiring spiral 35 mempunyai nilai tegangan terkecil. Prosntase selisih tegangan bending maksimum yang terjadi antara straight bevel gear dan spiral bevel gear dengan variasi sudut spiral 35 derajat sebesar 44,3%. Sedangkan selisih tegangan kontak maksimumnya sebesar 20,5%. Sehingga secara keseluruhan spiral bevel gear lebih baik daripada straight bevel gear. Kata Kunci- spiral bevel gear, tegangan bending, tegangan kontak, FEM.