The purpose of this study is to investigate the proper Stress Concentration Factor (SCF) of a multi-planar double KT (DKT) tubular joint. So far the design of multi-planar tubular joints in offshore structures based on the formulation for simple tubular joints that result in over/under prediction of the SCF of the joint. This situation in turn decreasing the accuracy of fatigue life prediction of the structures. The SCF is one of the most important parameters in the tubular joint fatigue analysis. In this paper a 60o two-planar DKT tubular joint of a wellhead offshore platform is modelled as a finite element model with bending loads acting on the braces. The effect of dimensionless geometrical parameters (β, τ, 𝛾) on the SCF distribution along the weld toe of braces and chord on the joint are investigated. The finite element models of the joints cover a wide range of geometrical parameter. Validation of the finite element model has shown a good agreement to the global structural analysis results. The result of this study is the SCF value of any non-dimensional variation due to bending loading case with the SCF was significantly differ to the SCF of an uni-planar KT join.
Department of Ocean Engineering, Faculty of Marine Technology, Institut Teknologi Sepuluh Nopember, Indonesia
This paper is a part of research in searching an appropriate damper for space structures constructed in seismic areas with two main purposes. First, the introduced damper should be able to restore a large displacement of structure due to heavy load, and the second, the damper should be also used to absorb a seismic energy through a yielding of uncritical part inside the damper. The first study had numerically investigated mechanical characteristics of a single U-plate under cyclic loading, and then followed by an advanced study for a full model of hysteresis damper which is built of a set of U-plate dampers. The latest study showed a feasibility of the introduced damper to act as a damper as well as energy absorption through yielding because of a heavy load. However, under a heavy load, yielding firstly occurred in curved area of plate of U-damper and the residual plastic deformation after unloading is quite large. It means that the plate of the damper is considerably damaged, therefore the new plate is required. To avoid this condition, the current study aims to substitute the previous critical area to another part which considerably is uncritical during loading. Therefore, in this paper, an additional part in form of slender column is inserted into damper. The bottom part of the column is clamped to the base plate of the damper, consequently there is a restoring moment acting on the column. This restoring moment is considered able to restore a large displacement to at least a small residual plastic displacement after unloading. If the yielding is still occured, the damage can be localized in slender column, therefore a main plate of the damper is still safe. A rigidity and strength of modified damper are determined by a nonlinear finite element technique which involves both geometrically and materially nonlinearities. The model was subjected by a monotonic increasing load which is applied both horizontally and vertically through method of displacement control until one cycle of hysteresis is formed. The stiffness of the damper is directly determined from load–displacement graph. The final result is in a term of comparison of hysterisis curves between a full model of hysterisis damper with and without a slender column.
Laboratory of Structural Dynamics, Department of Mechanical Engineering, Universitas Andalas, Indonesia
Laboratory of Structures and Material, Department of Civil Engineering, Universitas Andalas, Indonesia
Prediction of the intensity of extreme waves is one of the importance of information about ocean waves especially for the safety of a variety activities on offshore, on an annual basis, with reference to relatively limited wave data based on data in the period 2004-2014 at the north of Jakarta’s coast obtained by BMKG. By using a Weibull statistical distribution function, the study shows that the maximum wave height of the 10-year period, 50-year period, and 100-year period are 1.89 meters, 2.15 meter, and 2.23 meters. Also, by using the same pattern it can be obtained that the peak wave period of the 10-year period, 50-year period, and 100-year period are 9.33 seconds, 9.51 seconds, and 9.58 seconds.
Department of Ocean Engineering, Faculty of Marine Technology, Institut Teknologi Sepuluh Nopember, Indonesia
Cable-stayed bridge is a type of bridge structure that commonly used for long-span range. This study provides an important opportunity to advance the understanding nonlinearities of material and geometry which is used for pylon of cable-stayed bridge structure. This study limited to response of pylon structure subjected to tension load which already calculated previously using structural analysis program. The methodology of structural analysis in order to determine working stress in the pylon structure under cable tension load is based on non-linear finite element method by incorporating an elastic-plastic material model and involve large deformation logarithm. In this study, laboratory experiment was held using test method ASTM A370. In finite element of plasticity analysis Ramberg-Osgood model was used to generate stress-strain curve of material. Based on finite element analysis that we have done, both of pylon structure will be fail or experience permanent plastic deformation if it subjected to loading conditions as mentioned in this research. The most critical regions in the structure are at Section A2 for left side pylon and at Section A11 for right side pylon. In critical regions, maximum Von-Misses stress reach 427.96 MPa for left side pylon and 430.56 MPa for right side pylon. Those stress value are beyond yield strength of material which is used for the structure. Design optimization can be done for the structure with some considerations, e.g. modification of design in the critical region, improve material properties or just change thickness of material in the critical regions.
Department of Mechanical Engineering, Faculty of Engineering, Universitas Riau, Indonesia
Center for Electricity and Mechatronics, Indonesian Institute of Sciences, Indonesia
Tree is an important part of urban ecology. However, the condition of trees from time to time should be routinely observed in order to avoid the case of falling trees that often take casualties. There are several types of tree defects that can trigger the fall of a tree, such as decay, cancer, crack, etc. So far, there have been several methods to detect such defects as an early indicator of tree condition, for example by acoustic tomography, intrusive indentation, etc. In this study, a detection method is proposed by using natural frequency analysis (modal analysis) of a tree. The selected tree is palm tree. As an initial step, an analysis is required to determine the changes occurring in the natural frequency of palm trees that are affected by, 1) geometric aspects, such as diameter and tree height, 2) morphological aspects, such as the presence or absence of decay and its position on the tree. Natural frequency analysis is done with the help of FEM software. The result shows that the change in natural frequency is not very significant, in the range of 10% to 11%. Therefore, to be able to identify the condition of a tree, further research is needed.
Departement of Mechanical Engineering, Faculty of Engineering, Universitas Indonesia
Hydropower is the most advanced and mature renewable energy technology and provides some level of electricity generation in many countries worldwide. Small scale (low head and low flow rate) is still a challenging area because its cost-effective and ecologically acceptable exploitation of hydropower machine. Screw turbine is one mode of the small scale hydropower machine that is fairly recent turbine, many has yet to experiment with this. One blade screw turbine is used, and this paper reports on a performance of single blade screw turbine on some inclination angle position. The screw turbine has shown good potential to be used for low head pico or micro hydro power generation.
Energy Conservation and Renewable Energy Group, School of Engineering, RMIT University, Melbourne, Victoria 3083, Australia
Mechanical Engineering Department, Faculty of Engineering, University of Bengkulu, Bengkulu 38371A, Indonesia
This study aims to conduct a study with the Active Noise Control experimental method by comparing the first two conditions of noise before using ISD 4004 module (Non Active Noise Control) and second after using ISD 4004 module (Using Active Noise Control) to obtain noise reduction on Supra X 125D exhaust. Measurements were performed with variations of rotation 1000rpm, 2000rpm, 3000rpm and 4000rpm with horizontal, vertical, and axial directions. From the results obtained is the noise of Supra X 125D Exhaust without using the active noise control device, the largest noise value is in the axial direction (Z) rotated 4000rpm and distance of 0.75 meters with a value of 80.4 dB. While using the active noise control device, the largest noise value in the axial direction also (Z) is rotated 4000 rpm and distance of 0.75 meters with a value of 79 dB. From this result, we get the comparison between the exhaust before using ISD 4004 Module and afterwards using ISD 4004 Module we get the biggest reduction value on the active noise control device on the axis (Z) at 1000rpm rotation with distance 1.5 meter with the value without ISD 4004 65.5 dB Module and using ISD 4004 61.5 dB Module. Difference between these two conditions in the reduction of 4 dB. For the smallest reduction value is on the axis (X) rotated 2000 rpm and the distance 0.75 meters with the value before using ISD 4004 Module 65.9 dB and after using ISD 4004 Module 65.7 dB and obtained 0.2 dB reduction difference in these two conditions.
Laboratory Noise and Vibration Research Centre, Departement of Mechanical Engineering,Universitas Sumatera Utara, Indonesia
Erosion is one of main problem in coastal area. Currently, natural coastal protection using vegetation such as mangrove is preferable in many places in the world (Othman, 1994; Gedan et al., 2010). However there are challenges in development of this natural coastal protection, e.g. mangrove-trees have been damaged by the waves or current, before they are growth strongly. This study focused on a combination of main natural protection and temporary manmade structures. The main protection consists of mangrove plant vegetation, expected to serve long-term protection. While temporary structure is designed to protect the growth of young mangrove from the waves and erosion, it is designed as a non-conventional rubble mound structure made of geobag with a design life is determined by growth period of mangrove seeds. The concept design criteria is considered suitable for the remote area 1) low cost; 2) manually constructed; and 3) mangrove as the main protection.
Ocean Engineering, Faculty of Civil and Environmental Engineering, Institut Teknologi Bandung, Indonesia
A simple machine has been developed at the small jute mill in Majalaya, Bandung that uses coconut fiber and jute yarns to manufacture 100 % natural fiber prefabricated vertical drain. The machines implement weaving technology of jute yarns to form the filter sheath and coir yarn as core. The result of the assembly in manufacturing process is a Prefabricated Vertical Drain (PVD) made of natural jute fiber and coconut coir designed to accelerate consolidation of soft clayey soil. It has high tensile strength to withstand installation stresses and excellent water discharge capacity. The cross section of natural fiber PVD measures 80-120 mm in width and 8–12 mm in thickness and have a tensile strength of above 7 KN. In general, the properties of this drain are found comparable with other typical synthetic drains. The present drain differs from the others drain is that it is manufactured in existing jute mills machinery, the manufacturing process entails low energy consumption, and has capability of varying the width, thickness and weight per linear meter to suit different soft clayey soil conditions. An important feature of the jute burlap is its swelling nature that allows it to function as filter without clogging. And it is biodegradable and hence environmentally friendly.
Faculty of Engineering, BINUS University, Jakarta, Indonesia
One of the welding technology is SMAW (Shielded Metal Arc Welding) has its own advantages, such as, the current as the heat source used can be varied, easy to use in various welding positions, penetration and the electrode width of welding can be adjusted. In order for proper welding speed, this research uses SMAW welding machine with sliding adaptive vertical system that varies the flow and welding speed to the welding characteristics, by doing visual observation and mechanical properties using tensile test. The welding speed is controlled using arduino uno with stepper motor rotation as the driving force. The material used is mild steel which has been tested for its composition content, the groove used is single V groove with 60 ° andelectrode used is E6013 electrode. The number of specimens varied by 9 specimens with the highest tensile strength is 543,48 MPa and the lowest value is 253,75 MPa. Micro welding structure is determined by many factors including heat input, current strength, welding speed, and cooling rate. In this study the HAZ area has a larger grain structure than base metal and weld metal.
Department of Mechanical Engineering, Faculty of Engineering, Universitas Riau, Indonesia
In each welding technology each has advantages in accordance with the placement of its implementation. One of the welding technologies is the SMAW (shield metal arc welding) has an advantage over the current and the welding angle can be varied, and the penetration width of the electrode fuses can be adjusted. This research uses SMAW welding machine with sliding adaptive vertical system design for proper welding speed. This study varied the angle and speed of welding to determine the welding results of SMAW welding machine with sliding adaptive vertical system. In this study the characteristics of welding results based on visual observation and mechanical properties using tensile test. The parameters are varied angles 600, 650, and 750 and welding speed controlled arduino uno with a stepper round of 1.5 Rpm, 1.75 Rpm, and 2 Rpm. The material used is a low carbon steel, using a hometown V with 60 hill angle. In this study the highest metal tackling region is the tensile strength of 571.35 MPa and the lowest value is 475.52 MPa with the number of specimens varied by 9 specimens. Micro welding structure is determined by many factors including heat input, current strength, welding speed, and cooling rate. In this study the HAZ area has a larger grain structure than base metal and weld metal.
Department of Mechanical Engineering, Faculty of Engineering, Universitas Riau, Indonesia
Friction welding is a solid-state welding without the use of filler metal by using pressure method where by two workpieces to be connected are placed in contact and regulated relative motion in pressure, so that on the contact surface there will be heat (close to the metal liquid point), then after the rotation is stopped will form metal connection. Friction welding in the laboratory technology production of the University of Riau there are some disadvantages, namely the electric motor as a driver head stock stems are often damaged due to overheating such as excessive during welding, thus interfering with the welding process due to damage to the electric motor therefore carried out the development of friction welding tool by using flywheel. The Flywheel stores energy during high engine speed, and passes it during low engine speeds to produce a steady turn. in this study used three flywheels with a diameter of 250 mm each thick 10 mm, 20 mm, and 30 mm, from the test obtained the value of the average tensile strength on each flywheel is 522.736 MPa, 510.648 MPa, 531.79 Mpa.
Laboratory of Production Technology, Department of Mechanical Engineering, Faculty of Engineering, Universitas Riau, Indonesia
Laboratory of Material Testing, Department of Mechanical Engineering, Faculty of Engineering, Universitas Riau, Indonesia
Riau Province is one of the largest palm oil producers in Indonesia. Pome of biogas is one form of renewable energy that can be utilized through biogas power plants. One of the biogas power plant in Riau is a Rama-Rama biogas power plant in Kampar. As a first step to improving power plant efficiency, this plant has been identified as the location of the largest loss in power plant by energy analysis. Energy analysis were performed for a gas engine with multiple cylinder on biogas power plant 835 kW otto cycle. The data from the plant’s record books using for this analysis. The result, each gas engine cylinder has different efficiency values. The highest and lowest energy efficiency of gas engine found in cylinder 11 and cylinder 7, respectively 56,12% and 56,02%. That different efficiency value occurred due to the fact that there are large temperature differences between the combustion process every cylinder and the working fluid.
Department of Mechanical Engineering, Faculty of Engineering, Universitas Riau, Indonesia
Wind energy as one of renewable energy resource has a great potential to solve the problem of dependency on fossil fuels, especially in Pekanbaru, Indonesia. Pekanbaru wind speed condition which is considered relatively low can be harnessed efficiently by designing blades which suits wind condition in Pekanbaru. Blades are designed using aerodynamic equations and software assistance such as Microsoft Excel, Qblade, and Autodesk Inventor. As a result, the blades can generate mechanical power at low wind speeds with a radius 1.1 m and hub 0.2 m and the chord length at the base of the blade 0.13 m and at the tip 0.26 with twist angle at the base of the blade 20.4 and at the tip 5.6. The result of this research is to show that the inverse taper blade design is applicable in low wind speed conditions in order to produce an affordable, compact, and efficient wind turbine appropriate for wind characteristic in Pekanbaru.
Department of Mechanical Engineering, Faculty of Engineering, Universitas Riau, Indonesia
