Elsadig Mahdi

Design of Qatar University's first solar car for Shell Eco-marathon competition

Research and development in the area of renewable energy is growing fast, supported by the increasing awareness about sustainability, environment and limitation of conventional sources of energy. Interestingly, oil and gas companies are realizing the potential of renewable energy, and have been supporting events and competitions that aim precisely at developing technologies and expertise for this field. Shell is one of these companies; it has been organizing the yearly Shell Eco-marathon competition in three continents for decades now. Qatar Universitys students have participated in the latest edition of the race in the solar car category, held in Germany in May 2011. The team was made up of electrical and mechanical engineering students form the both departments. In this first participation, the aim was to design the first prototype of energy efficient solar and GTL cars to be starter point for a regular participation in future races. This paper discusses all the designing steps, components selection, measurements, calculations and manufacturing process that led to the first prototype of the solar car. A brief is given about the lessons learnt from the first participation and about the plans for the next participation in Shell Eco-marathon Asia in Malaysia in July 2012.

Current status of tissue engineering in the management of severe hypospadias

Hypospadias, characterized by misplacement of the urinary meatus in the lower side of the penis, is a frequent birth defect in male children. Because of the huge variation in the anatomic presentation of hypospadias, no single urethroplasty procedure is suitable for all situations. Hence, many surgical techniques have emerged to address the shortage of tissues required to bridge the gap in the urethra particularly in the severe forms of hypospadias. However, the rate of postoperative complications of currently available surgical procedures reaches up to one-fourth of the patients having severe hypospadias. Moreover, these urethroplasty techniques are technically demanding and require considerable surgical experience. These limitations have fueled the development of novel tissue engineering techniques that aim to simplify the surgical procedures and to reduce the rate of complications. Several types of biomaterials have been considered for urethral repair, including synthetic and natural polymers, which in some cases have been seeded with cells prior to implantation. These methods have been tested in preclinical and clinical studies, with variable degrees of success. This review describes the different urethral tissue engineering methodologies, with focus on the approaches used for the treatment of hypospadias. At present, despite many significant advances, the search for a suitable tissue engineering approach for use in routine clinical applications continues.

Investigating the Corrosion under Insulation (CUI) on Steel Pipe Exposed to Arabian Gulf Sea Water Drops

This paper is an endeavor to investigate an insulated mild steel pipe that exposed to three sea water drops rate (10, 30, and 50 drops/minute) at room temperature. Various experimental strategies were employed including visual inspection; scanning electron microscopy (SEM) with EDAX. After removing the insulation material, it was observed that pipes were corroded. However, the extent of corrosion was varied which was attributed to the drop rates, it was revealed that corrosion process was initiated due to water and ions penetration through the insulation, such revelation highlighted the necessity to properly examine the pipe and the insulating material. Results also revealed that severity of corrosion is proportional to the drops rates. EDAX analysis of the pipe surface and the insulating material shows the presence of difference ions including Na+, Cl-, Mg2+, Si2+ and others, the results highlighted the importance of material selection and the necessity for early detection strategy in order to avoid catastrophic failure.

Energy Absorption Capability of Composite Hexagonal Array Systems: Numerical Analysis

In this paper, in-plane dynamic crushing test of E-Glass hexagonal array systems has been carried out numerically, using LS-DYNA FE software package. Two array systems of woven E-Glass/epoxy hexagonal were studied; single column array system and multi-column array system. The volume of material used in all models was constant. The significant effects of changing arrays’ sequences and number of E-Glass layers in the hexagonal cells on the energy absorption capability are investigated. To validate the FEM, a single 45º hexagonal was modelled and crushed in X1 direction; the obtained numerical results were compared with the experimental results in terms of energy absorption capability, deformation modes and load-displacement curves, showing good agreement. Results obtained from single column array system showed that 1×4 array exhibited the higher energy absorption capability, whereas in multi-column array system, 4×3 array had the maximum value of energy absorbing compared to the whole studied models in this paper. As a conclusion, the multi-column array system has a higher energy absorption capability compared to the single column array system.

Assessment of Effectiveness of Date Palm Fibers in Foam Filled CFRP Energy Absorption Devices

The effectiveness of date palm fibers as a second order filler was assessed in octagonal/hexagonal hybrid energy absorption devices.. The cells inside the device were made from carbon fiber-reinforced plastics CFRP whereas; the outer skin was of Aramid/epoxy. The energy absorption devices were filled by date palm fibers and then the liquid foam was applied. The idea is to use the fibers to absorb the energy in various damage mechanisms and use the foam as a binder. The comparison showed higher peak load and average crushing load (for some cases) for the specimens filled with date palm and foam together. On the other hand, the specimens filled with foam only showed higher stroke efficiency and lower weight which led to a higher specific energy absorption.

Energy Absorption Capability of Cotton Fiber/Epoxy Composite Square and Rectangular Tubes

ABSTRACT This paper investigates the energy-absorption capability of natural fiber cotton fabric/epoxy square tubes. The cross-sectional aspect ratio was varied randomly from 0.50 to 2.57. Quasi-static crushing tests in axial and lateral directions were performed. Experimental results showed that the axially loaded rectangular tubes have higher load carrying capacity and energy absorption capability compared to the laterally loaded tubes. However, laterally crushed tubes have stable crush force efficiency; which means they are safer and more stable energy absorber devices. The experiment also showed that the cross-sectional aspect ratio significantly affects the load carrying and energy absorption capability. The buckling failure mode has been identified as the primary failure mode for the rectangular tubes under the different loading conditions. Tubes with cross-sectional aspect ratio of 2.0 have the best load carrying capacity.

Microscopic Study of 5083-H321 Aluminium Alloy Under Fretting Fatigue Condition

Fretting occurs where there is small amplitude oscillating motion between solid surfaces in contact. With even small loads or prolonged operation, fretting may lead to crack initiation followed by fretting fatigue. Its effect on fatigue is to speed up the nucleation of fatigue surface cracks and it can be extremely damaging. Fretting fatigue is a critical concern in aircraft structures and a widespread problem in naval structural components and is often the root cause of fatigue crack nucleation in machine components. In this investigation, fretting fatigue study is carried out using 5083-H321 marine/ aerospace aluminium alloy. The test rig and the experiments were designed with an emphasis to study the crack initiation behaviour in the fretted region using scanning electron microscope (SEM). Fretting damage and its relationship to the fretting fatigue life are presented and discussed.

Crushing Behavior of Composite Hexagonal Ring System

An extensive experimental investigation of inplane crushing of composite hexagonal ring system between platens has been carried out. Woven roving glass/epoxy hexagonal ring system with different angles and arrangement were employed. The rings angles are varying between 45 and 70°. The wet winding process was used to fabricate the woven E-glass fabric /epoxy specimens. Four layers of woven E-glass fabric/epoxy wrapped over wooden mandrel to get thickness of about 3 mm. The composite hexagonal tubes were then cured at room temperature (32oC) for 24 hours to provide optimum hardness and shrinkage. Repeatability of the results was ensuring by performing the experiments on three identical specimens. Typical histories of their crushing mechanism are presented. Behavior of ring as regards the initial crushing load, post crushing load, energy absorbed and mode of crushing has been presented and discussed. Results showed that the crush failure loads and energy absorption capability are greatly affected by the hexagonal ring geometry, arrangement and loading conditions. As the ring angle increases the energy absorption capacity increases. Composite hexagonal ring with 70 degree exhibited the highest energy absorption capability among tested specimens. It is also found that energy absorption capability for systems crushed in-plane X2 higher than X1.