Browsing by Author "Durowoju, M. O."

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Aircraft Disasters- roles of materials
(2009) Asafa, T. B.; Durowoju, M. O.; Ismail, O. S.
Aircraft disaster has been in existence since air was conquered by man as a means of transportation. 487.5 million and 874.4 millions of cumulative departures and flight hours respectively have been estimated since 1959. Analysis of aircraft failure based on 5,149 on-board fatalities recorded shows that 13% of total aircraft accident was caused by mechanical failure while loss of control was responsible for over 31% of onboard fatalities. Aircraft accident is known to be most fatal during take-off and landing phase contributing about 49% while onboard fatality during cruise is about 19%. In this work, reviews of aircraft disasters were made via Fractographic examination, SEM and finite element modeling. It must be stated that few of aircraft failures which are not material related are not considered in this review. The review focused on material related failure which have been analyzed, accepted and published in reputable journals.
Detection of the point of crack initiation using multi-stage random sampling (MRS) and spatial point pattern (SPP)
(Blackwell Educational Books, 2010) Durowoju, M. O.; Asafa, T. B.; Ismail, O. S
Porosity is a major defect in cast aluminum alloys affecting in particular, the fatigue strength. The pores serve as points of stress concentration and points of crack initiation for eventual failure. In this work, fractal analysis was used to numerically characterize the pores in uni-directionally solidified Al 4.5 wt % Cu alloy micrographs, transverse section at a distance of 14mm from the metal/chill mold interface. The Spatial Point Pattern (SPP) and the Multi-stage random sampling (MRS) methods were used to determine the distribution of the pores and the point of crack initiation leading to eventual failure. The MRS method reveals that all the pores considered are of irregular shapes, i.e shrinkage pores, with sphericity β < 0.3. The "worst" of the shapes is the pore in the upper left region with β= 5.3078e-010 and D = 1.8949. The SPP method confirms the result of the MRS method because crack initiation will commence in a region with clustered pores.
Optimal parameter in theeconomic pipeline distribution of jatropha oil
(Society for Interdisciplinary Research, 2011-06) Durowoju, M. O.; Ismail, O. S.; Oladosu, K. O.
Due to gradual depletion of world petroleum reserves and the environmental pollution of increasing exhaust emissions, there is an urgent need to develop alternative energy resources, such as biodiesel fuel. One way of reducing the biodiesel production costs is to use the less expensive feedstock containing fatty acids such as inedible oils, animal fats, waste food oil and by products of the refining vegetables oils. The fact that Jatropha oil cannot be used for nutritional purposes without detoxification makes its use as energy or fuel source very attractive as biodiesel. Due to its high flash point, Jatropha oil has certain advantages like greater safety during storage, handling, and transport. However, this may create problems during starting. The viscosity of Jatropha oil is less as compared with other vegetable oils but it is higher than diesel. To lower the viscosity and density of Jatropha oil, preheating is necessary prior to pumping. However, additional costs are incurred through heating and heating cost increases with temperature. This suggests the existence of an optimum temperature to which the fluid can be heated at minimum cost. This work is therefore, a study carried out to determine the optimum heating temperature for a given pipe diameter. The study of fluid flow was carried out and modified to incorporate cost concept to produce a mathematical model that predicts the economic heating temperature. The effect of pipe diameter on these temperatures was investigated via a computer code developed in Matlab 7.3 programming language. The result obtained showed that as the pipe diameter increased from 0.042m to 0.062m, the optimum heating temperature is maintained at 30°C. Results of this nature can be utilized in industries where pumping of Jatropha oil as an alternative fuel is sine-qua-non.