Christiaan Adika Adenya

Jomo Kenyatta University of Agriculture and Technology

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Jialong Jiao

South China University of Technology

Huilong Ren

Harbin Engineering University

Shuzheng Sun

Harbin Engineering University

Chaohe Chen

South China University of Technology

James Mutua

Jomo Kenyatta University of Agriculture and Technology

Hui Li

Harbin Engineering University

Fakher Jribi

Pan Africa Christian University

Chrispin Ouko Zamzu

Pan African University Institute for Basic Sciences, Technology and Innovation

John Kihiu

Jomo Kenyatta University of Agriculture and Technology

Thomas Ochuku Mbuya

University of Nairobi

Cooperative Institutions

Harbin Engineering University

Jomo Kenyatta University of Agriculture and Technology

South China University of Technology

Dalian University of Technology

Yeungnam University

University of Lisbon

Pan African University Institute for Basic Sciences, Technology and Innovation

University of Nairobi

Naval University of Engineering

Beijing University of Chemical Technology

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EFFECT OF TRANSITION ELEMENTS ADDITIONS ON MICROSTRUCTURE AND TENSILE PROPERTIES OF A SECONDARY Al-7Si-Mg CAST ALUMINIUM ALLOY

International journal of Engineering Technology and scientific Innovation (2021)

Chrispin Ouko Zamzu Thomas Ochuku Mbuya Christiaan Adika Adenya Timothy N Ngigi

The economic and environmental benefits of recycling aluminium alloys have increased the need to consider re-designing the alloys.The key challenge in recycling Al alloys is the varied chemical composition of the Al scrap.The effect of Ti, Sr, Cu and transition elements Zr and V additions on tensile properties of secondary cast 356 Al-Si alloy has been investigated with the aim of designing and producing premium automotive parts such as cylinder heads.The secondary cast 356 Al-Si alloy (base alloy) and its variant 356 + 0.5Cu + X (X = 0.15% Ti + 0.15% Zr + 0.25% V + 0.015% Sr) was cast, HIP ped and T6 heat treated.There was notable improvement in the ultimate tensile strength (UTS) and Yield strength (YS) of the base alloy upon addition of the elements.At room temperature, the UTS improved from 224 MPa to 279.3 MPa while the YT improved from 210 MPa to 268 MPa.At high temperature (237 o C), the UTS and YT improved from 149 MPa to 186 MPa and from 122 MPa to 167 MPa respectively.These improvements in strengths were however accompanied by a decrease in percent elongation, from 5% to 4.4% and from 8% to 6.8%, at room and high temperatures respectively.The decrease in ductility with the element addition can be attributed to the increased amount of course brittle intermetallic phases.At high temperature (237 0 C), the strengthening phases in the base alloy undergo Ostwald ripening thus resulting in lower UTS and YT.On the other hand, the micro

6063 aluminium alloy

10.51193/ijetsi.2021.6501

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Experimental Investigation of Wave-Induced Ship Hydroelastic Vibrations by Large-Scale Model Measurement in Coastal Waves

Shock and Vibration (2016)

Jialong Jiao Huilong Ren Shuzheng Sun Christiaan Adika Adenya

Ship hydroelastic vibration is an issue involving mutual interactions among inertial, hydrodynamic, and elastic forces. The conventional laboratory tests for wave-induced hydroelastic vibrations of ships are performed in tank conditions. An alternative approach to the conventional laboratory basin measurement, proposed in this paper, is to perform tests by large-scale model measurement in real sea waves. In order to perform this kind of novel experimental measurement, a large-scale free running model and the experiment scheme are proposed and introduced. The proposed testing methodology is quite general and applicable to a wide range of ship hydrodynamic experimental research. The testing procedure is presented by illustrating a 5-hour voyage trial of the large-scale model carried out at Huludao harbor of China in August 2015. Hammer tests were performed to identify the natural frequencies of the ship model at the beginning of the tests. Then a series of tests under different sailing conditions were carried out to investigate the vibrational characteristics of the model. As a postvoyage analysis, load, pressure, acceleration, and motion responses of the model are studied with respect to different time durations based on the measured data.

Scale model

Hammer

Ship motions

Experimental data

Full scale

10.1155/2016/9296783

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Citations (14)

Stress Characterization in Thick Walled Cylinders with Elliptical Cross-Bores

Abstracts of postgraduate thesis (2012)

Christiaan Adika Adenya

An investigation was conducted to determine the elastic stress profiles in a thick walled closed ended cylinder with a radial elliptical cross-bore. The orientation of the elliptical cross-bore with respect to the cylinder axis was varied. Various crossbore to cylinder bore radius ratios were investigated. Investigations were also done for various geometries of the elliptical cross-bore. The aim of this research was to determine the stress profiles and stress concentration factors in the vicinity of an elliptical cross-bore with regard to changing orientation of the cross-bore. The research was also aimed at determining stress trends when the cross-bore geometry was changed. Investigations were done by computer simulation. An elastic three-dimensional finite element method computer programme in FORTRAN code was developed. The displacement formulation was used. Cylinder geometries of thickness ratios k=2.0, k=2.25 and k=2.5 were considered. Cylinder length was taken to be 9 times the wall thickness. The cross-bore was positioned at the centre of the cylinder to avoid any end effects. The Bauschinger effect was ignored. The results obtained showed that the maximum stress concentration factor was experienced when the major axis of the elliptical cross-bore lay in the meridional plane, whereas, the minimum stress concentration factor was experienced when the major axis of the elliptical cross-bore lay in the transverse plane.For an elliptical cross-bore of cross-sectional area equivalent to that of a circular cross-bore of cross-bore to cylinder bore radius ratio of 0.15, the stress concentration factor (SCF) was a constant at 2.1 for angle of rotation (AOR) of 74.5° for semiminor axis to semi-major axis ratio (b/a) between 0.3 and 0.7. For an elliptical crossbore of cross-sectional area equivalent to that of3a circular cross-bore of cross-bore to cylinder bore radius ratio of 0.20, the SCF was a constant at 2.1 for AOR = 73° for b/a between 0.3 and 0.7. For an elliptical cross-bore of cross-sectional area equivalent to that of a circular cross-bore of cross-bore to cylinder bore radius ratio of 0.25, the SCF is a constant at 2.1 for AOR = 72.5° for b/a between 0.3 and 0.7. The results obtained from this research give details on the stress profiles and SCF that arise for a radial elliptical cross-bore at any orientation with respect to the cylinder axis. These results form a good basis for re-evaluating existing data for design of cylinders with elliptical cross-bores. The program developed can be commercialized and used to collect further data for design.

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Experimental Investigation of the Behaviour of a Large Ship in Irregular Waves

International journal of engineering research in Africa (2016)

Christiaan Adika Adenya Hui Long Ren Jialong Jiao

A towing tank experimental investigation was carried out using a segmented scaled model of a large ship prototype to study its behaviour when sailing in irregular head waves. The tests were carried out for typical sailing speeds and wave conditions that would be encountered by the large ship at sea. The vertical plane motion of heave, pitch, and the accelerations at bow and stern, and the vertical bending moment load responses of the ship were measured and analyzed. The significant amplitude values of motion and load response of the ship for the investigated wave conditions and speeds were determined by using spectral analysis. Slamming induced whipping loads were also investigated for the studied sailing conditions. In addition, the load response characteristics were evaluated in both time-domain and frequency-domain. Increasing the sea state had a greater effect on the motion and load responses of the large ship than increasing the sailing speed.

Towing

Ship motions

Slamming

Seakeeping

Response amplitude operator

Sea state

Bow wave

10.4028/www.scientific.net/jera.23.103

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Formulation and Testing of the Recycled Low-Density Polyethylene Montmorillonite Polymer Composite for Drug Eluting Stents

International Journal of Mechanical Engineering (2024)

Ogutu John Bosco Bruno Robert Mose James Mutua Christiaan Adika Adenya

10.14445/23488360/ijme-v11i12p105

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A comprehensive study on the seakeeping performance of high speed hybrid ships by 2.5D theoretical calculation and different scaled model experiments

Ocean Engineering (2018)

Jialong Jiao Shuzheng Sun Jide Li Christiaan Adika Adenya Huilong Ren

Seakeeping

Towing

Ship motions

Sea trial

Response amplitude operator

Full scale

Scale model

10.1016/j.oceaneng.2018.04.051

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Citations (27)

Atmospheric Corrosion of Stainless Steel 304

International Journal of Engineering Research and Technology (2020)

Fakher Jribi Christiaan Adika Adenya James Mutua

Metal Materials are used for the construction of structures in sub-Saharan Africa.The typical welding and joining techniques are the Metal Inert Gas, Tungsten Inert Gas and Arc welding.Atmospheric corrosion is a serious problem and if not properly maintained, they can quickly become liabilities because of corrosion-generated leaks and service interruptions.Although the study of the corrosion are often simplified, the impact of the tanks for maintaining an adequate quality of water in the network without corrosion is of paramount.Three samples were exposed for nine days to outdoors atmospheric conditions (C3 corrosivity) and then to an immersion test for 30 days equivalent to 120 cycles according to the ASTM G50 and ASTM G44 standards.The weight-loss method was used for the measurements of weight loss of the material as a function of time.The samples were cut and welded using arc welding, metal inert gas and tungsten inert gaz.The welded samples were compared, and the result of the corrosion rate performed.The corresponding rate of corrosion from experiment for arc welding and Metal Inert Gas was 0.01 mm/y and for Tungsten Inert Gas was 0.004 mm/y.The corrosion resistance of stainless steel was explained by the very thin passive layer that prevents the iron from corrosion.The formation of this passive layer is closely related to the chromium content of the steel with a minimum of 10.5% Chromium produces a thin layer of oxide on the surface of the steel.Increasing the amount of Chromium gives an increased resistance to corrosion.Metal alloys undergo uniform chemical corrosion that attacks surface evenly.Therefore, the loss of mass per unit area and per unit of time can be determined during the immersion test.,For each of the three samples, measurement of the weight loss was done after 40, 80 and 120 cycles for a period of 30 days.The result of this study showed that the arc weld and the metal inert gas corroded faster and has a higher corrosion rate on the weld zone, whereas the tungsten welding was found to be the most resistant against corrosion attack.

10.37624/ijert/13.3.2020.484-489

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Reproduction of ocean waves for large-scale model seakeeping measurement: The case of coastal waves in Puerto Rico & Virgin Islands and Gulf of Maine

Ocean Engineering (2018)

Jialong Jiao Chaohe Chen Shuzheng Sun Christiaan Adika Adenya Huilong Ren

Seakeeping

Wave model

Wave height

Sea state

10.1016/j.oceaneng.2018.01.083

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Citations (5)

Estimation of springing response for 550 000 DWT ore carrier

Journal of Marine Science and Application (2016)

Christiaan Adika Adenya Huilong Ren Hui Li Di Wang

Springing

Towing

Hydroelasticity

Offshore geotechnical engineering

10.1007/s11804-016-1365-7

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Citations (5)

Development of a Shipboard Remote Control and Telemetry Experimental System for Large-Scale Model’s Motions and Loads Measurement in Realistic Sea Waves

Sensors (2017)

Jialong Jiao Huilong Ren Christiaan Adika Adenya Chaohe Chen

Wave-induced motion and load responses are important criteria for ship performance evaluation. Physical experiments have long been an indispensable tool in the predictions of ship's navigation state, speed, motions, accelerations, sectional loads and wave impact pressure. Currently, majority of the experiments are conducted in laboratory tank environment, where the wave environments are different from the realistic sea waves. In this paper, a laboratory tank testing system for ship motions and loads measurement is reviewed and reported first. Then, a novel large-scale model measurement technique is developed based on the laboratory testing foundations to obtain accurate motion and load responses of ships in realistic sea conditions. For this purpose, a suite of advanced remote control and telemetry experimental system was developed in-house to allow for the implementation of large-scale model seakeeping measurement at sea. The experimental system includes a series of technique sensors, e.g., the Global Position System/Inertial Navigation System (GPS/INS) module, course top, optical fiber sensors, strain gauges, pressure sensors and accelerometers. The developed measurement system was tested by field experiments in coastal seas, which indicates that the proposed large-scale model testing scheme is capable and feasible. Meaningful data including ocean environment parameters, ship navigation state, motions and loads were obtained through the sea trial campaign.

Seakeeping

Sea state

Sea trial

Scale model

Ship motions

10.3390/s17112485

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Citations (9)