Elsadig Mahdi

• Qatar University

This paper introduces glass fiber reinforced polymer (GFRP)-reinforced Polyvinyl Chloride (PVC) tubes, both corrugated and non-corrugated, designed as energy absorber devices. The PVC tubes were externally and internally reinforced with GFRP composite oriented at ±45 and subjected to quasi-static axial compression tests. Results indicated that all...

The research focus has shifted towards lightweight structures with high energy absorption capabilities due to advancements in automotive safety technology. This study specifically investigates the impact of cross-sectional area on the energy absorption characteristics of hemispherical composite shells. The experimental phase involves characterizing...

Fracture events pose a significant obstacle to the widespread use of short fiber reinforced polymer (SFRP) composites in diverse engineering applications, especially in lightweight structures [1]. This contribution introduces a phase-field approach to model ductile fracture events in SFRP composites under both quasi-static and fatigue loading condi...

The seismic vulnerability of concrete structures has prompted the development of innovative approaches to enhance earthquake resistance. Recent earthquakes have demonstrated the challenges of repairing concrete buildings damaged beyond feasible restoration. In response, research in structural engineering has increasingly focused on damage-resisting...

The bumper beam is a crucial component of the automobile bumper system, responsible for absorbing impact energy and enhancing the safety of passengers during collisions. This paper presents the design and experimental analysis of a 3D-printed composite-plastic hybrid light structure, designed as a collapsible energy absorber. Exploratory testing wa...

This paper examines the effect of fiber-reinforced plastic (FRP) types on the internal pressure capacity and corrosion behavior of joined metallic pipes. To this end, fabrication processes of aluminum pipes have been prepared to be used later for wrapping with different FRP and welding. The FRP used are kevlar fiber/epoxy (KFRP) and carbon fiber/ep...

This paper examines the crashworthiness performance of composite rectangular tubes using experimental and artificial neural network (ANN) techniques. Based on experimentally obtained values of different crashworthiness parameters under various loading conditions, ANN models are constructed to identify the optimum cross-sectional aspect ratio of cot...

In this paper, hybrid composite plates for ballistic protection were investigated experimentally and numerically, with a target to reduce the weight of currently used body armor inserts and, at the same time, satisfy the requirements of the National Institute of Justice’s (NIJ) ballistic protection standards. The current study has three phases to i...

The damage and fracture behavior of Fiber Reinforced Polymers (FRPs) is quite complex and is different than the failure behavior of the traditionally employed metals. There are various types of failure mechanisms that can develop during the service life of composite structures. Each of these mechanisms can initiate and propagate independently. Howe...

Dynamic tensile strength of brittle materials such as concrete is usually obtained by performing laboratory investigations such as direct tensile, Brazilian splitting, and spall tests. This research presents a study aimed to investigate numerically the dynamic behavior of concrete exposed to tensile loading at medium strain-rate. The dynamic tensil...

The circular economy (CE) proposes a closed-loop supply chain-based production system and reduces the ecological systems' negative impacts. CE proposes a paradigm shift from a linear economy to a circular economy with the principles of 3Rs: reduce, reuse, and recycle. CE applications can be a viable option for the sustainable production of polymeri...

Phase-Field (PF) methods of fracture have emerged as powerful modeling tools for triggering fracture events in solids. These numerical techniques efficiently alleviate mesh dependent pathologies and are very suitable for characterizing brittle as well as quasi-brittle fracture in a wide range of engineering materials and structures including fiber...

This work presents an approach for smart manufacturing focusing on Industry 4.0 to predict the load vs. displacement curve of targeted cotton fiber/Polypropylene (PP) composite materials while complying with the required intended properties. Experimental data for varying composite fiber percentage to characteristic load and earlier built artificial...

In this article, the energy absorption capability and crushing behavior of composite corrugated tubes have been studied experimentally and numerically under quasi-static axial slipping crushing loading. Five corrugations with angles ranging between 35° and 55° with 5° increment have been studied. Two different unidirectional fibers have been used;...

In this paper, artificial neural network (ANN) models are developed to predict the load-displacement curves for better understanding the behavior of cotton fiber/polyvinyl chloride (PVC) composites. Series of experiments were undertaken in the laboratory for a varying percentage of composite fiber to characteristic loading. Based on those experimen...

This paper introduces a new carbon fiber reinforced plastic (CFRP) structural system in the field of crashworthiness. CFRP hat-shaped and angle-shaped stiffeners were used to develop a double-hat collapsible energy absorption system. Three different design alternatives were investigated. The first alternative is an open-cell design (OC) consisting...

This paper introduces the date palm leaf fiber (DPLF) as a possible natural fiber candidate to the automotive applications. An extensive experimental program has been carried out to examine the energy absorption capability of rectangular tubes made of DPLF. The test rig has been designed to characterize different types of date palm leaf species. Th...

In this study, additively manufactured aluminum thin-walled tubes with different slit dimensions are proposed to improve energy absorption efficiency. A total of 18 samples, which varied in the number of slits, slit length, slit width, and slit ends, were tested under quasi-static axial compression at a rate of 20 mm/min. The deformation and failur...

In this study, an experimental investigation into the crushing behaviour of one dimensional composite hexagonal cellular structure between two plates has been carried out. The materials have been used to accomplish the studies are the plain weave E-glass fabric and the epoxy resin. The tested cellular structures are composed of 4 × 1 hexagonal cell...

The poster shows the behavior of X-100 steel pipeline in Arabian Gulf sea water

Fiber-reinforced composite repairs are becoming widely used as an alternative to the installation of welded, full-encirclement sleeves for repair of oil and gas transmission/transportation pipelines. The primary advantage of this repair over welded, full-encirclement sleeves is that the need for welding is precluded. However, the composite repairs...

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 effec...

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 shortag...

Background: Natural and synthetic fibers are known for their low density, easier fabrication than metallic in several engineering applications. Furthermore, their structural rigidity is high and they can be used for advanced applications, such as aerospace applications and automotive industry sector. Methods: Owing to this in depth, studies had bee...

This paper investigates the influence of multiple surface treatment, including chemical etching and plasma treatments, on the mode I inter-laminar fracture toughness (G1C) of aluminum/fiberglass fiber-metal laminates. Laser technology was employed to further enhance aluminum substrate surface morphology to promote micro-mechanical interlocks (MMI)...

In light of the new environmental regulations and the growth in ecological, economic and social awareness worldwide, the need for materials that made of natural resources is increasing rapidly. Therefore, this paper introduces the date palm leave fiber (DPIF) as a possible natural fiber candidate to the automotive^ energy absorption devices. To thi...

Sandwich structures made of composites are designed mainly for higher and efficient load capacity. Mostly, the use of composite materials in lattice core sandwich structures is limited to the face sheet; whereas, the core is usually made of metals due to the difficulty in producing the FRP lattice shape. A sandwich with a core made of FRP is believ...

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...

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 carryin...

Stress field in functionally graded (FG) rotating disks with non-uniform thickness and variable angular velocity is studied numerically. The elastic modulus and mass density of the disks are assumed to be varying along the radius as a power-law function of the radial coordinate, while the Poisson's ratio is kept constant. The governing equations fo...

Structural response and failure modes of honeycomb sandwich panels subjected to a shock (impulsive pressure) followed by a high velocity projectile impact were investigated using detailed finite element simulations. Performance of sandwich panels was quantified by maximum transverse deflection of the bottom face sheet and core crushing strain along...

Out of plane vibration of rotating disks limits their performances especially at certain critical speed. The critical speed of these disks may be affected by the presence of defects such as a circumferential crack. In this paper out of plane vibration of functionally graded (FG) rotating annular disks with a circumferential open crack is investigat...

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 pipe...

Out of plane vibration of rotating disks limits their performances especially at certain critical speed. The critical speed of these disks may be affected by the presence of defects such as a circumferential crack. In this paper out of plane vibration of functionally graded (FG) rotating annular disks with a circumferential open crack is investigat...

In this paper numerical investigations into the crushing of woven roving laminated conical system have been conducted. Energy absorption capability can be achieved if the longitudinal properties of composite structures are being utilized. This can only be done if the energy absorbing system post failure scenario would be mitigated to be tearing fai...

We highlight the effect of structural hierarchy and deformation on band structure and wave-propagation behavior of two-dimensional phononic crystals. Our results show that the topological hierarchical architecture and instability-induced pattern transformations of the structure under compression can be effectively used to tune the band gaps and dir...

Fiberglass reinforced and composite plastics causes hazardous air, land and water pollution. The most common products are fiberglass boats, but other products include furniture, corrosion resistant equipment, cultured marble bath fixtures, bathtubs, heat exchanger components, floating pier modules, large storage tanks, truck body components, and ma...

This paper examines the effect of the first 24 hours water absorption on the mechanical properties and morphology of the long date palm leave fiber (DPLF) and unidirectional reinforced epoxy composites. The mechanical properties that were evaluated are tensile and flexural. Laminates with 31.4% volume fraction of reinforcement was prepared using ha...

In the current paper a series of experiments were conducted to assess the crashworthiness of cellular hexagonal/octagonal composite device. Each device composed of 6 cells of carbon fiber reinforced composite (CFRP). Different arrangements of the octagonal and the hexagonal cells were studied. All the configurations were filled with foam. The main...

Aluminium alloy 6061 T6 circular specimens were joined using TIG and MIG welding methods. Heat Affected Zone (HAZ) and Base Metal (BM) were separated from each other. Potentiodynamic polarization and open circuit potential were employed to investigate the corrosion properties. Mechanical properties were evaluated using tensile, and hardness tests....

The present research aims to investigate the effects of MIG welding on the corrosion and mechanical properties of AA 6061 T6. A series of experimental techniques has been conducted to evaluate the corrosion and mechanical properties of the alloy. Polarization and open circuit potential tests were conducted by exposing various zones independently in...

Cellular carbon fiber-reinforced plastic (CFRP) composites, either unfilled or filled with foam, may be of interest for energy absorption application due to their improved crashworthiness. In the current paper, new combinations of octagonal and hexagonal cellular CFRP composites are introduced as energy absorption devices. Different arrangements of...

Tensile, Torsion, and Hardness behavior of welded and un-welded Aluminium Alloy 6061 T6 were investigated. Tests were conducted to evaluate the impact of tungsten Gas Arc welding (TIG) on some of the mechanical properties of the alloy. Different zones with different mechanical properties were created as a result of the welding process. Welding was...

Crashworthiness of fiber reinforced polymer composites is classified based on how they deform, fail and dissipate the energy in a controllable manner. Fuselage shapes were manufactured from hybrid glass/epoxy and cotton/epoxy layers. The effects of the test speed and fiber orientation were investigated. The results showed that significant effects o...

The effect of temperature on erosion-enhance pitting corrosion behavior of X100 steel has been investigated. Tests were performed at two temperatures with the help of open circuit potential (OCP), potentiodynamic polarization scan and electrochemical frequency modulation. A heating plate was used to change and maintain the temperature of electrolyt...

The migration of different cations through coated steel at two different negative potentials was evaluated. 0.6M of three different solutions was used as corrosion media. Electrochemical Impedance Spectroscopy (EIS), UTHSCSA Image Tool software, Energy dispersive X-ray Spectroscopy (EDAX), and visual inspection were used to conduct the study. Resul...

An experimental investigation to optimize the absorbed energy of axially crushed composite collapsible tubular energy absorber devices was carried out. Different fiber orientation were used in this study (0/90, 15/-75, 30/-60, 45/-45, 60/-30 and 75/-15). The cost effective wet wrapping process was used to fabricate the specimens. The quasi-static c...

An attempt has been made to investigate the effects of MIG welding on the corrosion and mechanical properties of AA 6061 T6. A series of experimental techniques has been conducted to evaluate the corrosion and mechanical properties of the alloy. The corrosion media used was 3.5% (wt) NaCl. Polarization and open circuit potential tests were conducte...

This study introduces a new composite semi-elliptical suspension spring by utilizing fiber reinforced composite strength in principal direction instead of shear direction. Three types of composites were tested, namely, carbon/epoxy, glass/epoxy and glass/carbon/epoxy. A comprehensive experimental investigation of composite semi-elliptical suspensio...

Corrosion of welded and un-welded Aluminum Alloy 6061 T6 was investigated by immersing specimens in 3.5% (wt) NaCl solution. Potentiodynamic and open circuit potential measurements were conducted. The mechanical properties were investigated using tensile strength, hardness, and torsion tests. Optical Microscopy and Scanning Electron Microscopy were...

An extensive investigation into the erosion-corrosion behavior and failure analysis of an offshore steel tubular joint has been carried out by using various electrochemical techniques, visual inspection, optical microscope examination, mechanical testing, microstructure examination, chemical analyses, Scanning Electron Microscope (SEM) examination,...

This research proposes a schematic physical interpretation of passive films formed on HSLA steel during potentiodynamic polarization in bicarbonate-oil aqueous emulsions. The interpretation is based on the numerical calculation of charge-transfer release during the passivation process which showed an obvious disparity with bicarbonate and oil amoun...

This paper explores some key electrochemical aspects associated to the corrosion of API-X100 steel in aerated carbonate solutions. Investigated by polarization and electrochemical impedance spectroscopy tests, the corrosion rates and potentials, the cathodic reactions, and passivation are studied from the perspectives of carbonate content and tempe...

The critical ratio of Cl  to HCO  concerning the corrosion rate has been determined with and without electrolyte erosion in 0.3 M NaHCO 3 by using various concentrations of NaCl for X52 and X100 steels. The open circuit potential (OPC) was recorded for both steels in electrolytes containing 0.3 M NaHCO 3 and 0.1 M NaCl without erosion, with elect...

In this paper the importance of causality factor 2 and causality factor 3 of electrochemical frequency modulation (EFM) for corrosion monitoring has been discussed in comparison to two newly found causality factors. The derivation of these new causality factors namely causality factor 4 and causality factor 6 has been summarized. Moreover, the reli...

Electrochemical Frequency Modulation (EFM), cyclic polarization scans, potential noise measurement and long-term exposure tests have been used to evaluate the effects of green tea and tobacco against corrosion. In this work, various corroding environments were used for brass, aluminum and carbon steel materials. The level of corrosion protection by...

The electrochemical noise (EN) and electrochemical frequency modulation (EFM) techniques have been compared for their use to detect pitting corrosion. To do this, experiments on different corroding systems showing passivation and pitting corrosion were carried out. These corroding systems were: (1) Aluminum in borate buffer solution with and withou...

In this paper the derivation of two new causality factors like causality factor 2 and causality factor 3 used in electrochemical frequency modulation has been presented. Moreover, the ability of electrochemical frequency modulation (EFM) to monitor uniform and pitting corrosion for different corroding systems has been discussed. In most cases, EFM...

The electrochemical frequency modulation (EFM) technique has been used to investigate its ability to monitor stress corrosion cracking (SCC) of sensitized stainless steel U-bend specimens in sodium thiosulfate (Na 2S 2O 3) and sodium chloride (NaCl) solutions. Type 304 (UNS S30400) stainless steel was sensitized for different times to vary the SCC...

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°. Six layers of woven roving E-glass fabric/epoxy wrapped over wooden...

A floating catalyst chemical vapor deposition (FC-CVD) method was designed and fabricated to produce high quality and quantity carbon nanotubes. The reaction temperature was optimized to produce high yield and purity of the carbon nanotubes. The reaction temperatures were varied from 500–850°C. The result shows that carbon nanotubes were observed f...

In this paper the derivation of two new causality factors like causality factor 2 and causality factor 3 used in electrochemical frequency modulation has been presented. Moreover, the ability of electrochemical frequency modulation (EFM) to monitor uniform and pitting corrosion for different corroding systems has been discussed. In most cases, EFM...

This paper describes a theoretical approach to compare two types of fiber reinforced composite materials for femoral component of hip implants. The natural fiber reinforced composite implant is compared with carbon fiber reinforced composite and the results are evaluated against the control solution of a metallic implant made of titanium alloy. Wit...

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 fab...

This paper examines the effect of fiber orientation angles and stacking sequence on the torsional stiffness, natural frequency, buckling strength, fatigue life and failure modes of composite tubes. Finite element analysis (FEA) has been used to predict the fatigue life of composite drive shaft (CDS) using linear dynamic analysis for different stack...

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 c...

Flares are considered as the last defense line in plants that produces flammable products. One of its major duties is burn harmful, unneeded gases and light liquids into the atmosphere. A typical flare is simply a set of equipments that safely combusts waste hydrocarbons at a pressure drop that does not compromise plant relief systems or cannot be...

Quasi-static tests are performed in order to determine the crash behavior of composite tubes. The specimens are made from woven fiber carbon/epoxy. The crash experiments show that the tubes crushed in a progressive manner from one end to the other of the tubes while delamination was - taking place between the layers. In the simulation works describ...

Rotating disks have many applications in the aerospace industry such as gas turbines and gears. These disks normally work under thermo mechanical loads. Minimizing the weight of such components can help reduce the overall payload in aerospace industry. For this purpose, a rotating functionally graded (FG) disk with variable thickness under a steady...

Elastic solutions for axisymmetric rotating disks made of functionally graded material with variable thickness are presented. The material properties and disk thickness profile are assumed to be represented by two power-law distributions. In the case of hollow disk, based on the form of the power-law distribution for the mechanical properties of th...

In this paper, short-carbon-fiber-reinforced polypropylene (SCF/PP) composites were prepared with melt blending and hot-pressing techniques. The tensile properties, flexural properties, hardness, and work of fracture (WOF) of this composite were investigated. Thermal stability of the composite was studied via the thermal gravimetric analysis (TGA)....

This paper presents the effect of corrugation geometry on the crushing behavior, energy absorption, failure mechanism, and failure mode of woven roving glass fibre/epoxy laminated composite tube. Experimental investigations were carried out on three geometrical different types of composite tubes subjected to axial and lateral compressive loadings....

This paper presents the elastic solutions of the gear wheels made of functionally graded material (FGM) with variable thickness subjected to rotating loads. The material properties and wheel thickness profile are assumed to be represented by two power law distributions. Solid and hollow wheels are considered and the solutions for the stresses and d...

This paper is intended to introduce the Bayesian network in general and the Naïve-Bayes classifier in particular as one of the most successful classification systems to simulate damage detection in engineering materials. A method for feature subset selection has also been introduced too. The method is based on mean and maximum values of the amplitu...

The crashworthiness behavior of the filament wound hexagonal plain weave glass fabric epoxy composite tubes subjected to quasi-static axial compressive loads has been evaluated. The composite hexagonal tubes were axially crushed between two parallel steel flat platens, where one was stationary and the other moving. Quasi-static crushing tests were...

A functionally graded (FG) rotating disk with axisymmetric bending and steady-state thermal loading is studied. The material properties of the disk are assumed to be graded in the direction of the thickness by a power law distribution of volume fractions of the constituents. First-order shear deformation Mindlin plate and von Karman theories are em...

Fretting fatigue tests have been carried out on 7075-T6 aluminium alloy and En24 steel as a pad material to study the crack initiation behaviour. An asymptotic analysis is carried out to study the equivalence of stress state at the edge of a rectangular pad for complete contact for the Dundur’s parameters, α, β and at notch root of an associated in...

An unique fretting fatigue test rig has been designed and fabricated to characterize the fretting fatigue damage process with a facility to view the crack which is being initiated in and around the contact zone during the test. The test rig incorporates load cells for normal and friction force measurements. The complete calibration details for the...

Fibre-reinforced polymer sandwiches are promising materials for reducing vehicle mass, thereby improving the fuel economics. Nonetheless, to fully explore these materials as the primary structures and energy absorbers in vehicles, it is important to understand the energy absorption capabilities of these materials. Hence, in the present work, compre...

Multi‐walled carbon nanotubes (MWNTs) were used to prepare natural rubber (NR) nanocomposites. Our first efforts to achieve nanostructures in MWNTs/NR nanocomposites were formed by incorporating carbon nanotubes in a polymer solution and subsequently evaporating the solvent. Using this technique, nanotubes can be dispersed homogeneously in the NR m...

A four-phase program to improve the specific energy absorbed by axially crushed composite collapsible tubular energy absorber devices was undertaken. In the first phase, examining of the crushing behaviour of non-triggered tubes was carried out. The second phase is aimed at obtaining the best position for the triggered wall. The third phase focuses...

For composites to compete in vehicle suspension applications, it is essential to control their failure by utilising their strength in principal direction instead of shear. This can be achieved efficiently by employing a new configuration instead of existing one. This study marries between an elliptical configuration and the woven roving composites....

In this paper, an innovative lightweight composite energy-absorbing keel beam system has been developed to be retrofitted in aircraft and helicopter in order to improve their crashworthiness performance. The developed system consists of everting stringer and keel beam. The sub-floor stringers were designed as everting stringer to guide and control...

It is proven experimentally that introducing corrugation along a shell generator together with a proper advanced composite material will enhance the crashworthiness performance of energy device units. This is because corrugation along the shell generator will force the initial crushing to occur at a predetermined region along the tube generator. On...