Browsing by Author "Nagesh, Bh."

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Analysis and design of berthing structure for handling bulk cargo
(Indian Maritime University, Visakhapatnam, 2019) Gaikwad, Amar G.; Patnaik, K. V. K. R. K.; Nagesh, Bh.
This paper presents basic ideas and terminology of structural optimization of a berthing structure which was analysed and designed using different load conditions and the best possible way to construct a new berthing structure. All the suitable and useful data was adopted from the proposed site location at Belekeri port in Karnataka state and studied carefully before designing the structure. The berth is to be designed for a vessel having capacity of 120000DWT. The structure is subjected to various forces and combinations such as, High tide, Earthquake, High winds, heavy live loads as per IS: 4651-1983.The proposed berthing structure Model was generated with suitable geometry using STAAD-Pro software, after which all considerable loads on the structure were induced and analysed carefully. Different sectional dimensions were trialed during the analysis and the most acceptable structure was designed with providing all structural members with suitable reinforcement and satisfying all marine safety conditions. This research is an attempt to understand the concept of design and analysis of berthing structures under different conditions of loading.
Application of flux cored arc welding (fcaw) without pre-heating for heavy structures in ship building fabrication & construction of heavy offshore structural steels /
(Journal of Construction Engineering, Technology & Management, 2020-06-04) Rao, K.S. Jagan; Nagesh, Bh.; Kumar, I.N. Niranjan
In fusion welding processes, the reason often given to explain the need for preheating, controlling the inter pass temperature (in multi-pass welds), and post-weld heat treatment (PWHT) is to reduce the risk of residual stresses and it can be removed by heating weldment in the heat affected zone (HAZ). Cold cracking is a hydrogen embrittlement phenomenon, often referred to as hydrogen induced cracking or HAZ cracking. During the construction and fabrication of heavy offshore structures, several failures have been noticed during the welding of structures with higher plate thicknesses where preheating is not properly done. However, many welding engineers cannot readily arrange the preheating in offshore structures, oil and gas installations and in other locations where heavy ship building activities are being done. In this context, experimental studies have been performed on transient heat transfer in welding distortion control by using flux-cored arc welding process (Dual Shielded-DS) without application of pre-heating as specified by the various welding international codes. The authors have studied various samples and tested them in which the FCAW welding has been done with and without preheat. The eight-step welding method enunciated by welding standards with preheating has been slightly modified into again eight step method without preheating and still obtained the same strength, toughness, hardness and stiffness. The use of tubular electrodes with very small diameters has extended the use of this process to work pieces of smaller section size. A main advantage of using flux-cored arc welding (DS) is the ease with which specific weld-metal things can be developed. By adding alloying elements to the flux core, resulting in increased tensile strength and hardness. The process is easy to automate and is readily adaptable to flexible manufacturing systems and robotics.
Design of high speed slamming planing craft
(Indian Maritime University, Visakhapatnam, 2019) Hadassah, T.; Nagesh, Bh.; Niranjan Kumar, I. N.
This paper chronicles the hypothetical study, test results, design aspects such as stability characteristics, vessel’s high speed performance i.e. short take-off and landing distance, and vertical take-off and landing characteristics, operating at low shallow draft,high speed propulsion efficiency sans cavitation interference, less machinery operating noise, compact hullform & structure, efficient conveyance and applications of High Speed Slamming Planing craft (HSSP). Amongst High Speed Performance Marine Vessels, this is one of the unique design proposition; based on the research, facsimile, exploratory and hypothetical study of a genus of large corytophanid lizards also known as basilisks moving on the water surface and on parallel study of the small high speed vessels.
Friction and wear properties of rapid solidified H-Al-17Si alloys processed by UV assisted stir - squeeze casting with DLC-Star (CrN + a-c:H) coating under HFRR /
(Faculty of Engineering, 2020-12-14) Nagesh, Bh.
Tribological properties of rapid solidified hyper eutectic AlSi17Cu3.5-4Mg0.6-0.8 (H-Al-17Si) alloy were investigated under different loading conditions. The alloy was produced by the rheo-stir squeeze casting process with the T-6 condition. Experimental studies were conducted using high frequency linear reciprocating rig (HFRR) with a ball-on-plate geometry. The effect of applied load (10-50 N) on the wear and friction (COF) coefficients were studied under dry, lubricated (SAE15W40), and coated dry (DLC-Star) sliding conditions. For dry and lubricated sliding, COF values of hyper eutectic AlSi17Cu3.5-4Mg0.6-0.8 alloy were 0.26 and 0.042. A lower COF value of 0.013 was recorded with DLC-star (CrN + a-c:H) coating under dry condition. Whereas, the least wear coefficient is also observed with DLC-star coating (4.6X10-5 mm3/N.m) compared to the dry and lubricated sliding conditions (2.7X10-3 mm3/N.m and 3.8X10-4 mm3/N.m). The developments in COF and wear coefficients were mainly attributed to the distribution and size of primary Si granules and the formation of transfer layers on the coated surfaces of AlSi17Cu3.5-4Mg0.6-0.8 alloy. Surface morphologies were examined using SEM, AFM, surface roughness profilometer, and advanced metallurgical microscope (AMM) analysis techniques.
Motion characteristics of a research vessel for short-term voyage
(Indian Maritime University, Visakhapatnam, 2019) SaiKiran, Lekkalaa.; Pradhyumna, S. K.; Pavan Kumar, G. V. V.; Nagesh, Bh.
All floating bodies are subjected to 6 degree of freedom due to various encountering forces. The design challenge lies in reducing the excessive ship behaviour and design a comfort class ships. Research vessel in specific to be design to best comfort since they can have used by non-seafarers. This paper shows the study on motion characteristics of the vessel where the real- time data measured from the newly built coastal research vessel. The data is obtained from the ships Motion Response Unit for the entire duration of the voyage which is approx. 6 hr. 30 mins. The results obtained indicate a peak roll amplitude of 12.03 Degree and average of 6.0 degree. The peakheave motion obtained 1.8m, pitch of 4.39 degree, surge of 3.9 and, sway of 7.6m.The results obtained indicate that the vessel behaved in a normal condition within the acceptable criteria in the sea state 3 which favourable for carrying out scientific activities. The dampening devices like the bilge keel, Anti-roll tank and other devices helped in improving the vessel performance.
River trash cleaner.
(Indian Maritime University, Visakhapatnam, 2019) Upendra, M.; Hadassah, T.; Nagesh, Bh.; Niranjan Kumar, I. N.
With the increase in global plastic pollution in rivers/lakes which is adversely affecting the human and aquatic life. In this paper we present the design and analysis of Zero emission River Trash Cleaner (z-RTC) which is a electrically operated self-propelled floater with trash collecting arms and trash processing plant on the floater. The z-RTC collects the trash and the processing plant on the floater separates the plastic from the trash. The design and analysis of the z-RTC covers the general arrangement, stability, hydrodynamics and structural analysis. The collected plastic will be converted to lubricant oils by having an on-site pyrolysis plant. The last section of the paper discusses about the benefits and cost estimation of z-RTC.
Study on the failures of raw water tower structural joints when the air gap of the jack up rigs is increased
(2019) Nagesh, Bh.; NiranjanKumar, I. N.; MadhuLatha, N.
It is quite common to convert the existing offshore installation from one form to another mode, depending upon the next charter requirement. The Rig Owners intend to convert the age old offshore drilling rigs which are basically designed for drilling of oil and gas (called as Mobile Offshore Drilling Unit - MODU) into Mobile offshore Production Units (MOPUs). While doing so, the important element to be noticed is the air gap between the water line to the bottom of hull vis-à-vis the operating depth at site specific conditions. The air gap which normally increases compared to when the same has been used as a MODU, due to the reason that it is a fixed platform and regular jacking operations cannot be performed whereas rules call for the supporting structure to with stand the 100 years of wave and wind data in which case the wave height can be expected upto 14m and wind speeds of upto /exceeding 100 knots. As per rules the bottom of hull should be elevated to a height of at least 1.5m more than the highest wave that can occur including the surge, swell etc. In such a conversion the important parameter that is being missed out is the Raw Water Tower whose length also to be increased to meet the increased water depth and as such it will not be able to withstand the 100 years wave and wind criteria. This paper shows the study conducted on the Raw Water Tower (RWT) of a rig which is under conversion. The study is done by conducting the Global Strength Analysis. The Finite Element Method is used to determine the stresses and strains in various joint sections of the RWT by modelling the same in SACS modelling and FE analysis software which is extensively used in offshore industry. The structure is analysed as a discrete element model using beam elements. The stiffness analysis for the Raw Water Tower includes the computation of resultant stresses in members due to bending, shear, tensile & buckling stresses and checking it against the respective acceptable values.