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"Most of the existing water gates in Indonesia was made of iron or/and wood. Both materials are relatively easy to rusted , damaged or decayed and also attractive to be stolen. Alternative material and design was needed to overcome this issues. This study aim to design water gates using alternative material rather than iron.i.e GFRP (Glass Fiber Reinforced Plastics). This material has several advantages compared to the other material [such as metal] especially its weight, strength and price. The gate in this study was designed for width of 50 cm and 120 cm. Estimated optimal thickness for these width respectively 12 and 30 mm. Mechanical strength testings were conducted according to the Japanese Industrial standard for flexural strength. Testing conducted on two tipes of samples that have different thicknesses, i.e 12 mm and 30 mm. The average density of sample was 1,5 gr/cm, sample with 12 mm and 30 mm thickness reach fexural strength respectively about 200 kg/cm and 299 kg/cm at 10 mm strain. This result comply mechanical strenght requirement for water gate. Thus, recommended thickness for GFRP water gate was thicker than estimated,i.e was 10 mm for width of 50 am and 20 mm for width of 120 cm. The GFRP water gate with round shape in the bottom has contraction coefcient (c)= 0,951 and a value of dischage coefcient (c) can be determined by C=C {h-w); with ko =15 and K1=0,062"

"Komposit polimer epoksi berpenguat serat gelas (GFRP) merupakan salah satu material yang dewasa ini sangat populer, karena nilai ekonomis dan kehandalan nya. Aplikasi GFRP pada lingkungan bawah air, menyebabkan terjadinya proses wet curing yang dapat mempengaruhi sifat mekanik. Penelitian ini membahas faktor-faktor yang dapat mempengaruhi kinerja dari material GFRP dan daya rekat komposit tersebut dengan logam, faktor-faktor tersebut diantaranya seperti durasi curing, temperatur dan salinitas. Komposit GFRP dengan dua tipe hardener yaitu poliamin dan siklikamin dimanufaktur dengan menggunakan metode hand lay-up. Spesimen GFRP selanjutnya dengan variasi durasi curing 12, 24 dan 48 jam dimanufaktur pada lingkungan udara, air laut dan air distilat dengan temperatur dan salinitas yang berbeda. Kemudian dilakukan pengujian tarik, tekuk dan impak serta uji kekuatan bonding dan pengamatan SEM. Dari hasil penelitian yang dilakukan, diperoleh kesimpulan bahwa GFRP dengan hardener poliamin gagal membuat ikatan crosslink pada proses wet curing, sedangkan dengan hardener siklikamin crosslink berhasil terbentuk, nilai karakteristik sifat mekanik pada proses wet curing sedikit menurun dibandingkan dengan proses dry curing, seperti hasil uji tarik menurun sebesar 10% dan uji daya rekat sambungan logam dengan komposit turun sebesar 16%. Pada penelitian selanjutnya dapat dilakukan uji coba dilapangan.

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Glass Fiber Reinforced Polymer (GFRP) is very popular among other material due to its economic value and reliability. As an application to subsea pipeline, the main challenge of GFRP is the process of wet curing which is required by epoxy composite to form a strong bonding of cross link in subsea environment and consequently can effect mechanical properties.

This study evaluated the factors that might affect the performance of epoxy composite material and its bonding to metal, i.e. curing duration, temperature, and salinity. GFRP composite with two different types of hardener which are polyamine and cyclic amine were manufactured by hand lay-up method. Then, the specimens were manufactured in atmospheric, sea water, and distillation water with different variables such as 12, 24, and 48 hours curing time; temperature; and salinity. Then, the specimens were tested for their tensile, flexural, impact, and bonding strength. The last, observation of fracture appearance was done by SEM.

Result of the study, concluded that GFRP with polyamine hardener was failed to create cross link on wet curing process while the one with cyclic amine hardener successfully created cross link. However, the mechanical characteristic was a bit lower, such as the tensile strength decreased to 10% and the adhesion strength of the bonding decreased to 16%. For the future, this study can be investigated by field testing."

"Material komposit telah berkembang menjadi bahan serbaguna yang sangat diminati dalam berbagai aplikasi, terutama dalam bidang pertahanan dan militer. Glass Fiber Reinforced Polymer atau GFRP, adalah salah satu  jenis material komposit yang paling umum digunakan dalam bidang manufaktur bahan komposit. Material seperti GFRP menawarkan potensi besar dalam hal ini, memberikan perlindungan yang efektif dengan berat yang lebih ringan dibandingkan dengan bahan tradisional seperti baja. Fokus penelitian ini adalah penggunaan simulasi Finite Element Method untuk pengujian balistik untuk menilai kinerja material komposit serat kaca dan matriks epoksi terhadap peluru jenis I 38 Special Round Nose dengan kecepatan 274 m/s dan jenis II 9 mm Full Metal Jacketed dengan kecepatan 334 m/s, sesuai dengan standar National Institute of Justice. Berdasarkan hasil dari simulasi, 48 lapis serat fiberglass/epoksi dapat menyerap energi kinetik dari peluru Special RN sebesar 165,0 Joule dan meneruskan energi kinetik sebesar 7,8 Joule. 80 lapis serat fiberglass/epoksi dapat menyerap energi kinetik dari peluru 9mm FMJ sebesar 216,7 joule dan meneruskan energi kinetik sebesar 23,7 Joule. Kerusakan yang terjadi pada serat fiberglass/epoksi adalah brittle fracture. Perubahan bentuk peluru pada kedua simulasi adalah bagian depan peluru dan mengalami deformasi menjadi bentuk kerucut (conical).

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Composite materials have evolved into versatile materials that are in high demand in various applications, especially in the defence and military fields. Glass Fiber Reinforced Polymer or GFRP, is one of the most commonly used types of composite materials in the field of composite materials manufacturing. Materials such as GFRP offer great potential in this regard, providing effective protection at a lighter weight compared to traditional materials such as steel. The focus of this research is the use of Finite Element Method simulations for ballistics tests to assess the performance of glass fibre and epoxy matrix composite materials against Type I 38 Special Round Nose bullets with a velocity of 274 m/s and Type II 9 mm Full Metal Jacketed bullets with a velocity of 334 m/s, in accordance with National Institute of Justice standards. The results of this simulation will produce a visual representation in three-dimensional form using Finite Element Analysis software. Based on the results of the simulation, 48 layers of fiberglass/epoxy can absorb the kinetic energy of a Special RN bullet amounting to 165.0 Joules and transmit kinetic energy of 7.8 Joules. 80 layers of fiberglass/epoxy can absorb the kinetic energy of a 9mm FMJ bullet amounting to 216.7 Joules and transmit kinetic energy of 23.7 Joules. The damage occurring to the fiberglass/epoxy is brittle fracture. The deformation observed in the bullets in both simulations shows that the front part of the bullets undergoes deformation into a conical shape."