Browsing by Author "Oluwole, O. O"

Now showing 1 - 4 of 4

Effect of degree of deformation on the mechanical properties of high temperature thermomechanically treated steel
(Asian Network for Scientific Information, 2006) Omotoyinbo, J. A; Olorunniwo, O. E; Ogundare, O.; Oluwole, O. O
The development of hgh strength materials, coupled with good formability, has always been the aim of material scientists. The effect of degree of deformation on the mechanical propehes of hgh temperature themomechanically treated steel (HTMT) has been investigated in this study. It has shown that an increase in percent deformation results in improvement in mechanical propehes. In order to have maximum strengthening, heavy deformation and low finishing temperature should be chosen.
Finite element modelling of stress distribution in spherical liquified natural gas (LNG) pressure vessels
(2011) Adeyefa, O. A.; Oluwole, O. O
"This work investigated the distribution of Von Misses stress in LNG Spherical Carbon Steel Storage tanks. Using the Finite Element Method and equations of elasticity, constant thickness carbon steel spherical storage tanks of 40 in. dia. 70in. dia of 1 in. shell thickness were subjected to different loading conditions from 500 to 4000Psi in incremental of 500 Psi. Spherical triangular elements based on shallow shell formulation were used for the model. The element has five degrees of freedom at each corner node, which are the essential external degrees of freedom without the degree of freedom associated with the in-plane shell rotation. The displacement fields of the element satisfy the exact requirement of rigid body modes of motion. The FORTRAN 90 coding was developed to obtain maximum Von Misses stress distribution with the tank subjected to different internal pressure and wind loadings. The results were then compared with the yield stress of the material of the tank. Von Misses stress is used as yield criteria whether to change tank material or increase the shell material thickness if yield stress is higher than the Von-Misses Stress. Results showed Von Mises stresses for a 40 in dia. Spherical shell with 1 in shell thickness able to withstand internal pressure loading alone up to 3500 Psi after which the shell thickness will no longer be able to withstand the loading. The 70in. dia. Vessel could only withstand internal pressure loading up to 2000 Psi. Validation of Finite Element modeling was done using ASME Section VIII Div 1 standard. Modeled results were observed not to be significantly different from ASME values (P>0.05). External wind effects alone on small dia. vessels was seen to be constant for all sides of the pressure vessel.
Influence of degree of cold-drawing on the mechanical properties of low carbon steel
(Scientific Research, 2011) Raji, N. A; Oluwole, O. O
Low carbon steel metal is used for the manufacture of nails. Steel wire with <0.3% C content is cold-drawn through a series of drawing dies to reduce the diameter of the wire to the required diameter of the nails. A 0.12%w C steel wire cold drawn progressively by 20%, 25%, 40% and 50% was investigated. The influence of the degree of cold drawing on the mechanical properties of the carbon steel material were studied using the tensile test, impact test and hardness test experiments in order to replicate the service condition of the nails. The tensile test was done on a Montanso® tensometer to investigate the yield strength and the tensile strength of the material as the degree of deformation increases. An Izod test was used to determine the impact toughness of the steel using the Hounsfield impact machine and the hardness numbers were obtained for the different degrees of drawn deformation of the steel on the Brinnel tester. The study used the stress-strain relationship of the tensile test experiment to study the effect of the degree of cold-drawing deformation on the yield strength and tensile strength properties of the low carbon steel. The yield strength of the material was observed to reduce with increasing degree of cold-drawing, an indication of reduction in the ductility and the tensile strength of the material reduced with increasing degree of cold-drawn deformation. The ability of the material to resist impact loads when nails are hammered reduced with increasing degree of drawn deformation as a result of strain hardening of the material after the drawing operation. However the resilience of the material to further cold drawn deformation increased with increasing degree of deformation as evident in the Brinnel hardness number which in-creases with the degree of drawing deformation. This is an indication of the material’s approach to brittleness as the degree of drawn deformation increases
Modelling of sintering behaviour of Al-49.6wt%Zn powder compacts
(2002) Oluwole, O. O; Obafemi, O. K.
Al-Zn alloys find commercial use in aircrafts and cars. During multiphase sintering of powders, dimentional changes take place. It is necessary to accurately predict what dimentional changes will occur so that post sintering operatings will take care of this change. The sintering behaviour of Al-49.6wt% Zn powder compacts has been studied. Mathematical models for the effect of pressure and temperature on dimensional changes during sintering were obtained. Sintering temperature was kept constant at 435oC.Powder compact size was also kept constant.It was observed that, at a compacting pressure of 288Mpa there was zero shrinkage after 6 minutes of sintering at 435oC. With compacting pressure less than 288MPa and sintering for 150minutes, there was no single pressure where both diametric and longitudinal shrinkage was zero. It was only possible to keep the longitudinal and diametric shrinkage as low as possible(0.35%) at a compacting pressure of 205MPa. This shows that it is possible to have no shrinkage in the sintering operation of AL-49.6wt%Zn powder compacts which implies that no post sintering operation is neccessary if dimensional accuracies are required.