The Experts below are selected from a list of 18 Experts worldwide ranked by ideXlab platform

Yuan Ru-hua - One of the best experts on this subject based on the ideXlab platform.

  • Motion of rocker arms of jacket Launch Barge after Launch operations
    Ocean Engineering, 2010
    Co-Authors: Yuan Ru-hua
    Abstract:

    The rocker arm on the jacket Launch Barge which is used for Launch is a transition installation equipped at the stern.According to the characteristic of movement about Barge and rocker arm,this paper establishes the coefficient differential equation which describes the movement of Barge-Rocker coupling system and puts forward a numerical method based on improved Runge-Kutta method.Then a 30000 ton jacket Launch Barge is taken as an example to compute the state of movement of Launched Barge and rocker arm,and the result is compared to that of the test.Furthermore,this paper discusses the main factors which affect the movement of rocker arm and presents the Barge drawing,trim angle,trim angle of rocker arm and the longitudinal position of gravity that relatively greatly influence the rocker arm at the moment of jacket and rock completely separated.However,the rationality of this model should be tested further by tank test and real ship statistics.

Wicaksono Priyo - One of the best experts on this subject based on the ideXlab platform.

  • Analisis Stress Quasi Dinamis Untuk Struktur Jacket Saat Peluncuran
    2018
    Co-Authors: Wicaksono Priyo
    Abstract:

    Jacket Launching merupakan proses yang singkat tapi sangat kritis karena memiliki resiko yang tinggi. Jika terjadi kegagalan dalam proses Jacket Launching, maka dapat menyebabkan kerusakan atau tenggelamnya struktur (Gerwick,1986). Analisis dinamis peluncuran struktur jacket melibatkan berbagai parameter, meliputi environmental conditions, spesifikasi Launching Barge , ballasting, dan juga struktur jacket itu sendiri. Pada analisis dinamis ini akan dicari titik kritis pada jacket structure dalam setiap tahapan peluncuran, dan juga akan dicari gerakan pada Launching Barge terhadap struktur jacket. Model yang digunakan adalah data Jacket Tugas Rancang Besar III. Untuk pemodelan awal jacket, digunakan software SACS lalu dikonversi ke MOSES. Untuk analisa digunakan MOSES yang menghasilkan stress jacket, stabilitas jacket dan RAO motion struktur (heave, roll, pitch). ======================================================== Jacket Launching is a short but very critical process because it has a high risk. If a failure occurs in the Jacket Launching process, it can cause damage or sinking of the structure (Gerwick, 1986). The dynamic analysis of jacket Launch involves various parameters, including environmental conditions, Launch Barge specifications, ballasting, and also the jacket structure itself. In this dynamic analysis will be searched for the critical point on the jacket structure in each stage of Launch, and also will be sought movement on Launching Barge against jacket structure. The model used is data TRB III. For initial jacket modeling, used SACS software then converted to MOSES. For the analysis used MOSES that produce stress jacket, jacket stability and RAO motion structure (heave, roll, pitch)

Chengmeng Sun - One of the best experts on this subject based on the ideXlab platform.

  • research on optimization of valve open time of the Launch Barge s ballast tanks
    Journal of Marine Science and Application, 2009
    Co-Authors: Chengmeng Sun
    Abstract:

    Launch Barge is an effective tool for transporting ship segments from one place to another in shipyards. During shifting of segments onto a Barge, the slideway on the Barge’s deck must be adjusted to maintain the same level as the wharf and also the Barge must be kept level by adjusting the water in the ballast tanks. When to open the adjusting valves is an important factor influencing the Barge’s trim during the water-adjustment process. Because these adjustments are complex a mathematical model was formulated, after analyzing the characteristics of the process of moving the segments onto the Barges deck, and considering the effects of this movement’s speed and variations in tidal levels during the move. Then the model was solved by the penalty function method, the grid method, and improved simulated annealing, respectively. The best optimization model and its corresponding solution were then determined. Finally, it was proven that the model and the method adopted are correct and suitable, by calculating and analysing an example.

Jahar Rahmat - One of the best experts on this subject based on the ideXlab platform.

  • Studi Pengaruh Kondisi Inisial Terhadap Operasi Peluncuran Struktur Jacket
    2018
    Co-Authors: Jahar Rahmat
    Abstract:

    Struktur jacket merupakan salah satu jenis struktur bangunan lepas pantai yang digunakan di perairan dangkal. Struktur jacket adalah struktur rangka baja yang terdiri dari kaki struktur dan rangka penunjang (brace) yang dikonfigurasikan dengan berbagai tipe perangkaan. Struktur tersebut dibangun di galangan kemudian dipindahkan, diangkut dan diinstal di lokasi struktur tersebut akan beroperasi. Pada saat proses instalasi tahap yang paling beresiko adalah tahap Launching. Pada tahap tersebut jacket diluncurkan ke dalam air menggunakan Launch Barge. Proses Launching dibagi dalam tiga tahap yaitu jacket slides, jacket tipping, dan jacket separation. Penelitian ini bertujuan untuk mengetahui pengaruh kondisi inisial Launching terhadap proses Launching dan analisa sruktur jacket selama proses Launching. Kondisi inisial yaitu sudut trim dan draft Launch Barge akan divariasikan untuk mengetahui pengaruh parameter tersebut terhadap motion Barge, bottom clearance jacket, reaksi rocker arm, durasi Launching (separation time), dan sudut trim Barge maksimum. Kemudian analisa tegangan maksimum dan unity check (UC) pada struktur jacket selama proses lauching. Analisa proses Launching dilakukan dengan bantuan software komersial. Pemodelan tiga dimensi jacket menggunakan software SACS 5.7. Model tersebut kemudian dikonversi ke software MOSES 7.10 untuk analisa Launching. Hasil penelitian menunjukkan bahwa variasi sudut trim Barge lebih signifikan pengaruhnya dari pada draft terhadap separation time, reaksi rocker arm, dan sudut trim Barge maksimum. Variasi sudut trim dan draft Barge tidak signifikan pengaruhnya terhadap perubahan bottom clearance jacket dengan seabed. Stabilitas Launch Barge pada 24 variasi kondisi inisial trim dan draft telah memenuhi syarat stabilitas. Rentang minimal stabilitas Barge adalah 49.02⁰, area rasio (K) minimum adalah 12.16 dan tinggi metacenter (GM) minimum adalah 22.90 m. Pada analisa struktur, tegangan axial maksimum struktur jacket dari 24 kondisi inisial sudut trim dan draft yang telah divariasikan adalah 122.09 MPa pada kondisi inisial sudut trim buritan 2.0⁰ dan draft 9.0 m. Tegangan tersebut telah memenuhi syarat karena tidak melebihi tegangan izin axial yaitu 245.6 MPa. Tegangan bending maksimum struktur jacket adalah 289.46 MPa pada kondisi inisial sudut trim buritan 3.0⁰ dan draft 8.5 m. Tegangan tersebut tidak memenuhi syarat karena melebihi tegangan izin bending yaitu 266.64 MPa. Dari 24 variasi sudut trim dan draft yang telah ditentukan terdapat 10 variasi yang tidak memenuhi syarat UC (unity check) struktur jacket

Sucahyono Tri - One of the best experts on this subject based on the ideXlab platform.

  • Analisis Stabilitas Jacket dengan Kegagalan Buoyancy Tank Saat Instalasi Pada Kondisi Vertikal
    2017
    Co-Authors: Sucahyono Tri
    Abstract:

    Tahap akhir dalam perancangan struktur jacket lepas pantai adalah menentukan metode instalasi. Terdapat 3 metode instalasi jacket yaitu, lifting, Launching, dan self-floating. Metode Launching adalah peluncuran jacket dari atas Launch Barge ke laut di lokasi instalasi jacket. Jacket yang menggunakan metode lauching sering dilengkapi dengan buoyancy tank sebagai penambah daya apung agar jacket dapat mengapung dengan sendirinya. Buoyancy tank dapat mengalami kebocoran baik karena fabrikasi yang buruk, kesalahan saat peluncuran, dan lain sebagainya. Maka dari itu, faktor kebocoran buoyancy tank perlu dipertimbangkan pda saat perencanaan. Faktor lain yang perlu dipertimbangkan adalah faktor lingkungan, terutama tinggi gelombang. Penelitian ini bertujuan untuk mengetahui gerakan atau stabilitas jacket saat mengapung dengan mempertimbangkan variasi kebocoran atau kegagalan buoyancy tank serta mempertimbangkan variasi tinggi gelombang untuk mengetahui rentang tinggi gelombang yang aman untuk proses instalasi. Variasi konfigurasi buoyancy tank meliputi variasi posisi (3 model), variasi jumlah (1 model), variasi dimensi (1 model), variasi orientasi (1 model). Variasi tinggi gelombang meliputi tinggi gelombang 1.65 ft, 2.7 ft, dan 5.4 ft. Hasil dari analisis menunjukkan, model jacket dengan RAO 0.5 – 0.9 ft/ft aman untuk proses instalasi dengan rentang tinggi gelombang ≤ 5.4 ft, sedangkan model jacket dengan RAO > 1.0 ft/ft aman untuk proses instalasi dengan rentang tinggi gelombang ≤ 2.7 ft. ========================================================= =============== The final stage in the design of an offshore jacket structure is to determine the installation method. There are 3 methods of jacket installation that is, lifting, Launching, and self-floating. The Launching method is the Launch of the jacket from the top of the Launch Barge to the sea at the location of the jacket installation. Jackets that use the lauching method are often equipped with a buoyancy tank as an added buoyancy to allow the jacket to float by itself. Buoyancy tanks can leak well due to poor fabrication, errors during Launch, and so forth. Therefore, the buoyancy tank leakage needs to be considered at the time of design. Other factors to consider are environmental factors, especially wave height. This study aims to determine the movement or stability of the jacket during floats by considering the leakage variation or the failure of the buoyancy tank and considering the wave height variation to find the safe wave height range for the installation process. The variations of buoyancy tank configuration include position variation (3 models), variation of number (1 model), variation of dimension (1 model), variation of orientation (1 model). Variations of wave height include wave height from 1.65 ft, 2.7 ft, and 5.4 ft. Results from the analysis show that jacket model with RAO 0.5 - 0.9 ft is safe for installation process with wave height range ≤ 5.4 ft, while jacket model with RAO > 1.0 ft is safe for installation process with wave height range ≤ 2.7 ft