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This paper examines the immature rupture of glass fiber reinforced plastic composite (GFRP) mitered elbow pipes. The GFRP composite mitered elbow pipe’s lifespan was twenty-five years; however, the pipes in question experienced immature failures, resulting in the reduction of their lifetimes to seven, nine, and ten years, respectively. The GFRP cooling water mitered elbow pipe’s service conditions operate at a pressure of up to 7 bar and temperatures between 15–36 °C. The root cause of failure was determined using visual inspection, analytical, microstructural, mechanical characterizations, and chemical analysis. The initial visualization inspection revealed an improper joint between the composite overwrapped and the straight pipe sections. Mechanical properties along the axial, hoop and 45° from the axial direction were obtained. The results from the analytical analysis indicated that the elbow might withstand the operating pressure depending on the quality factor, which was confirmed to be low due to the elbow joint’s improper fabrication process. As evidence of this, the numerical analyses’ results indicated that the safety factor in withstanding the operating pressure of 5 bar is dropped down in the radial region where the thickness is reduced to simulate the failure zone. This study’s findings recommend that thickness of less than 15 mm be reinforced using overwrapped composites. It is recommended for future installations that the fabrication process be appropriately monitored and controlled and avoids using 45°/−45° fiber orientation and multiple layers of chopped strand mat glass fiber.
Elsadig Mahdi Saad; Samer Gowid; John Cabibihan. Rupture of an Industrial GFRP Composite Mitered Elbow Pipe. Polymers 2021, 13, 1478 .
AMA StyleElsadig Mahdi Saad, Samer Gowid, John Cabibihan. Rupture of an Industrial GFRP Composite Mitered Elbow Pipe. Polymers. 2021; 13 (9):1478.
Chicago/Turabian StyleElsadig Mahdi Saad; Samer Gowid; John Cabibihan. 2021. "Rupture of an Industrial GFRP Composite Mitered Elbow Pipe." Polymers 13, no. 9: 1478.
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 improve the ballistic plate’s energy absorption capability. The first phase is devoted to studying the effect of the material types, including three different fibers: carbon fiber, date palm fiber, and Kevlar fiber. The second phase is dedicated to studying the effect of hybridization within layers. The two previous phases’ results were analyzed to optimize the material based on the hybrid composite ballistic plate’s maximum energy absorption capability. The commercial finite element software package LS-DYNA was employed for numerical modeling and simulation. The hybrid composite ballistic plate could absorb more impact energy than the non-hybrid Kevlar plate with the same area density from the numerical simulation results. This study provides lighter-weight ballistic inserts with a high protection level, making movement easier for the wearer. The numerical results were verified by comparing results of a plate made of 40 layers of Kevlar with an actual ballistic test. The results indicated that the simulation results were conservative compared to the ballistic test.
Farah Alkhatib; Elsadig Mahdi; Aamir Dean. Design and Evaluation of Hybrid Composite Plates for Ballistic Protection: Experimental and Numerical Investigations. Polymers 2021, 13, 1450 .
AMA StyleFarah Alkhatib, Elsadig Mahdi, Aamir Dean. Design and Evaluation of Hybrid Composite Plates for Ballistic Protection: Experimental and Numerical Investigations. Polymers. 2021; 13 (9):1450.
Chicago/Turabian StyleFarah Alkhatib; Elsadig Mahdi; Aamir Dean. 2021. "Design and Evaluation of Hybrid Composite Plates for Ballistic Protection: Experimental and Numerical Investigations." Polymers 13, no. 9: 1450.
In this study, glass fibre reinforced (GFRP) polyvinyl chloride (PVC) tubes were subjected to quasi-static axial compression tests to determine their crashworthiness performance. To this end, this study employed GFRP/PVC tubes with four different fibre orientations, 45°, 55°, 65° and 90°. A five-axis filament winding machine was used to fabricate the tubes. The results show that there was a considerable increase in all crashworthiness characteristics due to GFRP reinforcement. For the GFRP/PVC composite tubes of different fibre orientations, the load-bearing capacity, crush force efficiency and energy absorption capability generally improve with increasing fibre orientation. The GFRP/PVC 45° specimen was a notable exception as it exhibited the best specific energy absorption capacity and a crushing force efficiency that was only slightly less than for the GFRP/PVC 90° specimen.
Rahib Khan; Elsadig Mahdi; John-John Cabibihan. Effect of Fibre Orientation on the Quasi-Static Axial Crushing Behaviour of Glass Fibre Reinforced Polyvinyl Chloride Composite Tubes. Materials 2021, 14, 2235 .
AMA StyleRahib Khan, Elsadig Mahdi, John-John Cabibihan. Effect of Fibre Orientation on the Quasi-Static Axial Crushing Behaviour of Glass Fibre Reinforced Polyvinyl Chloride Composite Tubes. Materials. 2021; 14 (9):2235.
Chicago/Turabian StyleRahib Khan; Elsadig Mahdi; John-John Cabibihan. 2021. "Effect of Fibre Orientation on the Quasi-Static Axial Crushing Behaviour of Glass Fibre Reinforced Polyvinyl Chloride Composite Tubes." Materials 14, no. 9: 2235.
Recent polymer and metal additive manufacturing technologies were proven capable of building complex structures with high accuracy. Although their final products differ significantly in terms of mechanical properties and building cost, many structural optimization studies were performed with either one without systematic justification. Therefore, this study investigated whether the Direct Metal Laser Sintering (DMLS) and Fused Deposition Modelling (FDM) methodologies can provide similar conclusions when performing geometrical manipulations for optimizing structural crashworthiness. Two identical sets of four shapes of stiffened hexagonal cells were built and crushed under quasi-static loading. The results were compared in terms of collapsing behavior, load-carrying performance, and energy-absorption capability. Although the observed failure modes were different since the base-materials differ, similar improvement trends in performance were observed between both fabrication approaches. Therefore, FDM was recommended as a fabrication method to optimize thin-walled cellular hexagonal parameters since it was 80% more time-efficient and 53.6% cheaper than the DMLS technique.
Othman Laban; Elsadig Mahdi; Samahat Samim; John-John Cabibihan. A Comparative Study between Polymer and Metal Additive Manufacturing Approaches in Investigating Stiffened Hexagonal Cells. Materials 2021, 14, 883 .
AMA StyleOthman Laban, Elsadig Mahdi, Samahat Samim, John-John Cabibihan. A Comparative Study between Polymer and Metal Additive Manufacturing Approaches in Investigating Stiffened Hexagonal Cells. Materials. 2021; 14 (4):883.
Chicago/Turabian StyleOthman Laban; Elsadig Mahdi; Samahat Samim; John-John Cabibihan. 2021. "A Comparative Study between Polymer and Metal Additive Manufacturing Approaches in Investigating Stiffened Hexagonal Cells." Materials 14, no. 4: 883.
A primary concern of conventional Portland cement concrete (PCC) is associated with the massive amount of global cement and natural coarse aggregates (NCA) consumption, which causes depletion of natural resources on the one hand and ecological problems on the other. As a result, the concept of green concrete (GC), by replacing cement with supplementary cementitious materials (SCMs) such as ground granulated blast furnace slag (GGBFS), fly ash (FA), silica fume (SF), and metakaolin (MK), or replacing NCA with recycled coarse aggregates, can play an essential role in addressing the environmental threat of PCC. Currently, there is a growing body of literature that emphasizes the importance of implementing GC in concrete applications. Therefore, this paper has conducted a systematic literature review through the peer-reviewed literature database Scopus. A total of 114 papers were reviewed that cover the following areas: (1) sustainability benefits of GC, (2) mechanical behavior of GC in terms of compressive strength, (3) durability properties of GC under several environmental exposures, (4) structural performance of GC in large-scale reinforced beams under shear and flexure, and (5) analytical investigation that compares the GC shear capacities of previously tested beams with major design codes and proposed models. Based on this review, the reader will be able to select the optimum replacement level of cement with one of the SCMs to achieve a certain concrete strength range that would suit a certain concrete application. Also, the analysis of durability performance revealed that the addition of SCMs is not recommended in concrete exposed to a higher temperature than 400 °C. Moreover, combining GGBFS with FA in a concrete mix was noticed to be superior to PCC in terms of long-term resistance to sulfate attack. The single most striking observation to emerge from the data comparison of the experimentally tested beams with the available concrete shear design equations is that the beams having up to 70% of FA as a replacement to OPC or up to 100% of RCA as a replacement to NCA were conservatively predicted by the equations of Japan Society of Civil Engineers (JSCE-1997), the American Concrete Institute (ACI 318-19), and the Canadian Standards Association (CSA-A23.3-14).
Abathar Al-Hamrani; Murat Kucukvar; Wael Alnahhal; Elsadig Mahdi; Nuri C. Onat. Green Concrete for a Circular Economy: A Review on Sustainability, Durability, and Structural Properties. Materials 2021, 14, 351 .
AMA StyleAbathar Al-Hamrani, Murat Kucukvar, Wael Alnahhal, Elsadig Mahdi, Nuri C. Onat. Green Concrete for a Circular Economy: A Review on Sustainability, Durability, and Structural Properties. Materials. 2021; 14 (2):351.
Chicago/Turabian StyleAbathar Al-Hamrani; Murat Kucukvar; Wael Alnahhal; Elsadig Mahdi; Nuri C. Onat. 2021. "Green Concrete for a Circular Economy: A Review on Sustainability, Durability, and Structural Properties." Materials 14, no. 2: 351.
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 polymeric composite materials by decreasing the cost and improving product lifetimes and mechanical performance. This paper explores Khalasa date palm leaf fiber (KDPLF) as a reinforcement for polymeric composite materials. To this end, it is essential to examine their morphology, material properties, chemical composition, and water uptake. The investigated fiber was obtained from the Qatar University farm. The morphology examination was carried out using scanning electron microscopy. Thermogravimetric analysis has been used to examine the thermal stability of KDPLF. Morphological examination indicates that the lumen size for Khalasa is 32.8 ± 15.9 µm. The SEM morphology of the KDPLF cross-section showed high hemicellulose content. Tensile properties revealed that Khalasa fiber had tensile strength/tensile modulus of 47.99 ± 13.58 MPa and 2.1 ± 0.40 GPa, respectively. The results are also demonstrated that high variation in the mechanical properties and morphology was showed in KDPLF. Water uptake has significant effects on the properties of KDPLF/epoxy composite. Accordingly, as the moisture absorption of KDPLF/epoxy increases, its strength and stiffness decrease. As the moisture absorption of KDPLF/epoxy increases, its toughness increases.
Elsadig Mahdi; Daniel R. Hernández Ochoa; Ashkan Vaziri; Aamir Dean; Murat Kucukvar. Khalasa date palm leaf fiber as a potential reinforcement for polymeric composite materials. Composite Structures 2020, 265, 113501 .
AMA StyleElsadig Mahdi, Daniel R. Hernández Ochoa, Ashkan Vaziri, Aamir Dean, Murat Kucukvar. Khalasa date palm leaf fiber as a potential reinforcement for polymeric composite materials. Composite Structures. 2020; 265 ():113501.
Chicago/Turabian StyleElsadig Mahdi; Daniel R. Hernández Ochoa; Ashkan Vaziri; Aamir Dean; Murat Kucukvar. 2020. "Khalasa date palm leaf fiber as a potential reinforcement for polymeric composite materials." Composite Structures 265, no. : 113501.
Common quantitative assessments of neck injury criteria do not predict anatomical neck injuries and lack direct relations to design parameters of whiplash-protection systems. This study aims to provide insights into potential soft tissue-level injury sites based on the interactions developed in-between different anatomical structures in case of a rear-end collision. A detailed finite element human model has exhibited an excellent biofidelity when validated against volunteer impacts. Three head restraint arrangements were simulated, predicting both the kinematic response and the anatomical pain source at each arrangement. Head restraint’s contribution has reduced neck shear and head kinematics by at least 70 percent, minimized pressure gradients acting on ganglia and nerve roots less than half. Posterior column ligaments were the most load-bearing components, followed by the lower intervertebral discs and upper capsular ligaments. Sprain of the interspinous ligamentum flavum at early stages has caused instability in the craniovertebral structure causing its discs and facet joints to be elevated compressive loads. Excessive hyperextension motion, which occurred in the absence of the head restraint, has promoted a stable avulsion teardrop fracture of the fourth vertebral body’s anteroinferior aspect and rupture the anterior longitudinal ligament. The observed neck injuries can be mathematically related to head–torso relative kinematics. These relations will lead to the development of a comprehensive neck injury criterion that can predict the injury level. This, in turn, will impose a significant impact on the design processes of vehicle anti-whiplash safety equipment.
Othman Laban; Elsadig Mahdi; John-John Cabibihan. Prediction of Neural Space Narrowing and Soft Tissue Injury of the Cervical Spine Concerning Head Restraint Arrangements in Traffic Collisions. Applied Sciences 2020, 11, 145 .
AMA StyleOthman Laban, Elsadig Mahdi, John-John Cabibihan. Prediction of Neural Space Narrowing and Soft Tissue Injury of the Cervical Spine Concerning Head Restraint Arrangements in Traffic Collisions. Applied Sciences. 2020; 11 (1):145.
Chicago/Turabian StyleOthman Laban; Elsadig Mahdi; John-John Cabibihan. 2020. "Prediction of Neural Space Narrowing and Soft Tissue Injury of the Cervical Spine Concerning Head Restraint Arrangements in Traffic Collisions." Applied Sciences 11, no. 1: 145.
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 experimental data, the ANN models were trained and tested on the TensorFlow backend using Keras library in Python by implementing the back-propagation method. For better prediction and accuracy of the load-displacement curves, the grid search hyperparameter tuning method was used, followed by k-fold cross-validation. The developed approach proved to be very efficient and reduced the time and effort of the behavioral study for numerous samples, and it will help materials designers to design their future experiments effectively. A similar approach to predict load-displacement curves using ANN can be extended for any kind of composite material if the necessary experimental data are available.
Monzure-Khoda Kazi; Fadwa Eljack; E. Mahdi. Predictive ANN models for varying filler content for cotton fiber/PVC composites based on experimental load displacement curves. Composite Structures 2020, 254, 112885 .
AMA StyleMonzure-Khoda Kazi, Fadwa Eljack, E. Mahdi. Predictive ANN models for varying filler content for cotton fiber/PVC composites based on experimental load displacement curves. Composite Structures. 2020; 254 ():112885.
Chicago/Turabian StyleMonzure-Khoda Kazi; Fadwa Eljack; E. Mahdi. 2020. "Predictive ANN models for varying filler content for cotton fiber/PVC composites based on experimental load displacement curves." Composite Structures 254, no. : 112885.
An immature failure of a gas flare tip used in Qatar oil and gas offshore industry was investigated throughout this study. The design lifetime of the flare was fifteen years; however, it manifested immature failure resulting in a reduction of its lifetime to ten years. The flare is composed of different parts where the upper flare body and wind deflector showed failure while other components were still healthy. The material used for the aforementioned failed parts was Incoloy 800H, which is a highly corrosion and high-temperature resistant steel alloy. The material was rolled up and welded together with different welding joints. The root cause of failure was identified by using chemical analysis and microstructural and mechanical characterizations. For the mechanical characterization, an optical microscope (OM) and scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS) analyses were used for the specimen extracted from the failed part in order to ensure that the material mentioned by the manufacturer demonstrated the same metallurgical properties. For the mechanical characterization, two sets of specimens were used, one close to the failure region and the other far from the failure area. The chemical analysis revealed that the material was truthfully Incoloy 800H. The mechanical examination results showed a significant reduction of mechanical properties, i.e., the ultimate tensile strength (UTS) and microhardness dropped by 44% and 41% for samples close and far from the failure regions, respectively. Careful examination of the failed parts indicated that failure mostly took place in the vicinity of the welds, in particular near the joints. Improper joint designs, as well as a number of joints being designed in tiny areas, worsened the harmful effect of the heat-affected zone (HAZ), resulting in crack nucleation in the HAZ regions. The effect of welding in a combination of harsh service conditions of flare caused further crack extension where they merged, resulting in final immature failure.
Elsadig Mahdi; Ali Esmaeili. Failure Analysis of a Flare Tip Used in Offshore Production Platform in Qatar. Materials 2020, 13, 3426 .
AMA StyleElsadig Mahdi, Ali Esmaeili. Failure Analysis of a Flare Tip Used in Offshore Production Platform in Qatar. Materials. 2020; 13 (15):3426.
Chicago/Turabian StyleElsadig Mahdi; Ali Esmaeili. 2020. "Failure Analysis of a Flare Tip Used in Offshore Production Platform in Qatar." Materials 13, no. 15: 3426.
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; CFRP and KFRP and the corrugated tubes were fabricated by the wet filament winding process. Firstly, the corrugated tubes were experimentally tested. The slipping-force-stroke curves were obtained and failure modes have been analyzed. Based on the obtained curves, the calculated crashworthiness parameters were evaluated and presented. Scanning electron microscopy (SEM) images were taken to gain further insight into the experimental results. Secondly, LS-DYNA finite element code was used to numerically analyze the crushing response of the composite corrugated tubes. Mesh optimization and parametric study for the failure modeling parameters of the material model MAT 054 were carried out. The simulation results showed very good agreement with the experimental observations.
F. Alkhatib; E. Mahdi; A. Dean. Crushing response of CFRP and KFRP composite corrugated tubes to quasi-static slipping axial loading: Experimental investigation and numerical simulation. Composite Structures 2020, 246, 112370 .
AMA StyleF. Alkhatib, E. Mahdi, A. Dean. Crushing response of CFRP and KFRP composite corrugated tubes to quasi-static slipping axial loading: Experimental investigation and numerical simulation. Composite Structures. 2020; 246 ():112370.
Chicago/Turabian StyleF. Alkhatib; E. Mahdi; A. Dean. 2020. "Crushing response of CFRP and KFRP composite corrugated tubes to quasi-static slipping axial loading: Experimental investigation and numerical simulation." Composite Structures 246, no. : 112370.
This paper investigates the effect of filler content on the mechanical properties of cotton fiber (CF) on the CF/PP and CF/PVC composites under quasi-static loading. For this purpose, experimental tensile tests were carried out on dog-bone specimens, cut out from hot and cold press molded square plates of different fiber weight contents. The results obtained show that the filler content appears to have a strong influence on mechanical energy absorption, and failure characteristics. It was also found that the stiffness for both sets of material increases with the addition of filler. On the other hand, the ductility for both sets of the material increases with the addition of filler. The microscopic morphology study indicates that CF/PP possesses a glossy surface appearance compared to CF/PVC, which possesses a porous surface. Micro-scale damage characteristics from tensile tests indicate that material experienced shear failure, matrix cracking, fiber breakage, fiber fracture, and fiber pullout. The phenomenon of matrix crazing experienced by CF/PP composites was also observed.
Elsadig Mahdi; Aamir Dean. The Effect of Filler Content on the Tensile Behavior of Polypropylene/Cotton Fiber and poly(vinyl chloride)/Cotton Fiber Composites. Materials 2020, 13, 753 .
AMA StyleElsadig Mahdi, Aamir Dean. The Effect of Filler Content on the Tensile Behavior of Polypropylene/Cotton Fiber and poly(vinyl chloride)/Cotton Fiber Composites. Materials. 2020; 13 (3):753.
Chicago/Turabian StyleElsadig Mahdi; Aamir Dean. 2020. "The Effect of Filler Content on the Tensile Behavior of Polypropylene/Cotton Fiber and poly(vinyl chloride)/Cotton Fiber Composites." Materials 13, no. 3: 753.
An efficient reliability algorithm is developed to transfer the system reliability problem to a single-component reliability problem, considering the uncertainty of loading cases and the material properties. The main difficulty is that femoral bone densities change after hip arthroplasty and, thus, the mechanical properties of the distinctive bone tissues and, therefore, the corresponding elasticity modulus and yield stress values change. Therefore, taking these changes into account during the hip prosthesis design process is strongly needed. As the bone possesses anisotropic behaviors, as the material properties in both radial and tangential directions in long bone (femur, tibia) are almost similar, the bone anisotropy is represented in this study by transversal isotropy. Two optimized formulations for yield stress against the elasticity modulus relationship are first developed and then integrated into an efficient reliability algorithm. Thus, a coupling between reliability and optimization, so-called reliability-based design optimization (RBDO), is introduced in order to control the reliability level. The proposed RBDO algorithm using optimum safety factors (OSF) takes into account the material uncertainties and leads to new stem dimensions. An in-depth numerical analysis on a cementless hip prosthesis is implemented to demonstrate the appropriateness of the proposed algorithm with the consideration of many different loading cases. The results show that the studied model can be effectively used when compared to previous works, which concerns the changes in both geometry and material properties.
Ghais Kharmanda; Samer Gowid; Elsadig Mahdi; Abdallah Shokry. Efficient System Reliability-Based Design Optimization Study for Replaced Hip Prosthesis Using New Optimized Anisotropic Bone Formulations. Materials 2020, 13, 362 .
AMA StyleGhais Kharmanda, Samer Gowid, Elsadig Mahdi, Abdallah Shokry. Efficient System Reliability-Based Design Optimization Study for Replaced Hip Prosthesis Using New Optimized Anisotropic Bone Formulations. Materials. 2020; 13 (2):362.
Chicago/Turabian StyleGhais Kharmanda; Samer Gowid; Elsadig Mahdi; Abdallah Shokry. 2020. "Efficient System Reliability-Based Design Optimization Study for Replaced Hip Prosthesis Using New Optimized Anisotropic Bone Formulations." Materials 13, no. 2: 362.
In this study, the fiber-reinforced polymeric composite (FRP) overwrap system is proposed to eliminate the effect of the heat-affected zone on the pressure capacity and the deterioration property of the welded pipes. The proposed FRP overwrap system has many advantages. It is cost-effective, and it eliminates the external corrosion while increasing the pressure capacity of the welded pipes. In addition, it also prevents the unplanned shutdown of the pipelines. To evaluate the effectiveness of the proposed FRP overwrapped system, firstly, steel pipe specimens with welded regions were prepared. Secondly, the welded regions were overwrapped with composite material (glass fiber and epoxy resin) using filament winding machine. Finally, the fabricated specimens were tested using three-point and four-point bending tests using the Instron machine. All failure modes of the tested specimens were observed and analyzed using the scanning electron microscopy (SEM). It was proved that the use of the proposed FRP overwrap system had eliminated the effect of the heat-affected zone in welded/steel pipes. The results of three bending tests showed that the maximum flexural load for pipes with two and four welding lines has increased by 16.94 kN and 10.35 kN, respectively. On the other hand, for a four-point bending test, the maximum flexural load has increased by 26.8 kN.
Fatima Ghassan Al-Abtah; E. Mahdi; Samir Gowid. The use of composite to eliminate the effect of welding on the bending behavior of metallic pipes. Composite Structures 2019, 235, 111793 .
AMA StyleFatima Ghassan Al-Abtah, E. Mahdi, Samir Gowid. The use of composite to eliminate the effect of welding on the bending behavior of metallic pipes. Composite Structures. 2019; 235 ():111793.
Chicago/Turabian StyleFatima Ghassan Al-Abtah; E. Mahdi; Samir Gowid. 2019. "The use of composite to eliminate the effect of welding on the bending behavior of metallic pipes." Composite Structures 235, no. : 111793.
The aim of this paper is to establish a reliable model that provides the best fit to the specific behavior of the flow stresses of the 10%Cr steel alloy at the time of hot deformation. Modified Johnson–Cook and strain-compensated Arrhenius-type (phenomenological models), in addition to two Artificial Neural Network (ANN) models were established with the view toward investigating their stress prediction performances. The ANN models were trained using Scaled Conjugate Gradient (SCG) and Levenberg–Marquardt (LM) algorithms. The prediction accuracy of the established models was evaluated using the following well-known statistical parameters: (a) correlation coefficient (R), (b) Average Absolute Relative Error (AARE), (c) Root Mean Squared Error (RMSE), and Relative Error (RE). The results showed that both of the modified Johnson–Cook and strain-compensated Arrhenius models could not competently predict the flow behavior. On the contrary, the results indicated that the two proposed ANN models precisely predicted the flow stress values and that the LM-trained ANN provided a superior performance over the SCG-trained model, as it yielded an RMSE of as low as 0.441 MPa.
Abdallah Shokry; Samer Gowid; Ghias Kharmanda; Elsadig Mahdi. Constitutive Models for the Prediction of the Hot Deformation Behavior of the 10%Cr Steel Alloy. Materials 2019, 12, 2873 .
AMA StyleAbdallah Shokry, Samer Gowid, Ghias Kharmanda, Elsadig Mahdi. Constitutive Models for the Prediction of the Hot Deformation Behavior of the 10%Cr Steel Alloy. Materials. 2019; 12 (18):2873.
Chicago/Turabian StyleAbdallah Shokry; Samer Gowid; Ghias Kharmanda; Elsadig Mahdi. 2019. "Constitutive Models for the Prediction of the Hot Deformation Behavior of the 10%Cr Steel Alloy." Materials 12, no. 18: 2873.
This study aims to introduce a new pipeline joining technique using fiber-reinforced (FRP) composites. To this end, a comprehensive experimental program has been carried out to evaluate the new technique. The experimental program consists of four phases. In phase 1, a fabrication process in which aluminum pipes were employed for both types of joining (i.e., welding and joining by FRP is presented and discussed. Two types of welding have been used to study their effect on the pipe’s mechanical behavior. These are V welding and standard faced butt-welding techniques. For FRP joining, there are three types of fibers used. These are Kevlar fiber/epoxy (KFRP), carbon fiber/epoxy (CFRP), and glass fibers/epoxy (GFRP). Effect of fiber orientation angles of the joining system under three-point bending has been taken place in phase 2. The results showed that 00/900 orientation recorded the highest flexural load. In phase 3, the evaluation of welding types and fiber types effects on the bending behavior of joined pipes have been carried out. For the impact of welding types, V-welded pipes showed higher mechanical performance than normal faced butt-welded pipes. In addition, CFRP and KFRP joining system showed a higher value of flexural load than welding techniques, while the GFRP showed similar flexural load to welding techniques. Phase 4 involves assessment of FRP hybridization systems on bending behavior of joined metallic pipes. The improvement in the mechanical performance of pipes joined with four layers of hybrid FRP were found to be insignificant compared to four layers of non-hybrid FRP type. However, increasing the number of hybrid FRP layers to eight resulted in significant improvement in flexural loads compared to four layers of single FRP type. The overall results revealed that using FRP composites in pipes joining showing a promising future for the pipeline.
M.H. Farag; E. Mahdi. New approach of pipelines joining using fiber reinforced plastics composites. Composite Structures 2019, 228, 111341 .
AMA StyleM.H. Farag, E. Mahdi. New approach of pipelines joining using fiber reinforced plastics composites. Composite Structures. 2019; 228 ():111341.
Chicago/Turabian StyleM.H. Farag; E. Mahdi. 2019. "New approach of pipelines joining using fiber reinforced plastics composites." Composite Structures 228, no. : 111341.
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 cells with angles varied between 35° and 60°. Various crashworthiness parameters of the tested cellular structures such as crushing load capacity, energy absorption capability and force efficiency were computed and discussed. The crush failure modes of the tested rings were identified and analysed. Results showed that the hexagonal ring angle has a significant effect on the crush failure loads and energy absorption capability. Increasing the cell angle showed a decrease in energy absorption capability and load carrying capacity. Additionally, the cell angle has a remarkable effect on the failure sequence of the ring cells.
E. Mahdi; Munir Faraj; Abdel Magid Hamouda; S. M. Sapuan; M. A. Attiaa; E. O. Eltai; M. A. Attia. Effect of hexagonal on the in-plane crushing behaviour of plain weave composite hexagonal quadruple ring system. International Journal of Crashworthiness 2019, 25, 192 -202.
AMA StyleE. Mahdi, Munir Faraj, Abdel Magid Hamouda, S. M. Sapuan, M. A. Attiaa, E. O. Eltai, M. A. Attia. Effect of hexagonal on the in-plane crushing behaviour of plain weave composite hexagonal quadruple ring system. International Journal of Crashworthiness. 2019; 25 (2):192-202.
Chicago/Turabian StyleE. Mahdi; Munir Faraj; Abdel Magid Hamouda; S. M. Sapuan; M. A. Attiaa; E. O. Eltai; M. A. Attia. 2019. "Effect of hexagonal on the in-plane crushing behaviour of plain weave composite hexagonal quadruple ring system." International Journal of Crashworthiness 25, no. 2: 192-202.
The implementation of sustainable systems is an essential requirement in modern manufacturing, in order to minimize the environmental and health concerns, and conserves energy and natural resources. The sustainable manufacturing approach is identified through three main levels, namely: product, process, and system scales. The interactions among these levels provide the required sustainable target. To achieve a sustainable manufacturing system, it is very important to understand and define the concepts and needs related to the sustainability approach. In addition, defining and understanding the implementation steps as well as the assessment method to build a sustainable manufacturing system is required. In this work, a study discussing the sustainable manufacturing approach is presented in terms of concepts, implementation steps, and assessment methods.
Hossam A. Kishawy; Hussien Hegab; Elsadig Saad. Design for Sustainable Manufacturing: Approach, Implementation, and Assessment. Sustainability 2018, 10, 3604 .
AMA StyleHossam A. Kishawy, Hussien Hegab, Elsadig Saad. Design for Sustainable Manufacturing: Approach, Implementation, and Assessment. Sustainability. 2018; 10 (10):3604.
Chicago/Turabian StyleHossam A. Kishawy; Hussien Hegab; Elsadig Saad. 2018. "Design for Sustainable Manufacturing: Approach, Implementation, and Assessment." Sustainability 10, no. 10: 3604.
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 are fabricated by hand lay-up, which lacks fiber tension and resin content. A four-phase program to improve the pressure capacity of internally pressurized composite overwrapped damaged metallic pipes was undertaken. In the first phase, designing, fabricating of automated cost-effective composite repair system was carried out. The second phase focuses on the effects of composite overwrapped metallic pipes to understand the influence of fabric orientation angle on their responses of to the internal pressure. Phase three evaluates the improvement in pressure capacity of overwrapped damaged pipes by varying the fabric orientation. The fourth phase is devoted to investigate the corrosion resistance of the pipes. The results demonstrated the strong potential benefits of using new repair system. The fabric orientation of composite overwrapped exhibited a pronounced effect on the damaged pipes capability to carry high internal pressure. Composite overwrapped damaged metallic pipes exhibited high pressure capacity compared with externally damaged and non-damaged metallic pipes. .
E. Mahdi; E. Eltai. Development of cost-effective composite repair system for oil/gas pipelines. Composite Structures 2018, 202, 802 -806.
AMA StyleE. Mahdi, E. Eltai. Development of cost-effective composite repair system for oil/gas pipelines. Composite Structures. 2018; 202 ():802-806.
Chicago/Turabian StyleE. Mahdi; E. Eltai. 2018. "Development of cost-effective composite repair system for oil/gas pipelines." Composite Structures 202, no. : 802-806.
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 objective of the current paper was to examine the effect of using the aramid/epoxy instead of the carbon/epoxy layers to pack the device. The specimens were tested under quasi-static compression loading up to complete crushing. The results showed that the packing material did not have a significant effect for the case of all hexagonal open cells. For the other configurations, introducing the aramid/epoxy instead of the carbon/epoxy showed improvements in the stroke efficiency, the crush load stability, the average crushing load, the energy absorbed and the specific energy absorption. In order to understand the mechanisms that led to this improvement, the packing material were examine after crushing using an optical microscope and a scanning electron microscope (SEM). For the carbon/epoxy, the images showed many failure mechanisms whereas, for the aramid/epoxy, only delamination was noted.
E. Mahdi; Tamer Sebaey. Crushing behavior of hybrid hexagonal/octagonal cellular composite system: Aramid/carbon hybrid composite. Materials & Design 2014, 63, 6 -13.
AMA StyleE. Mahdi, Tamer Sebaey. Crushing behavior of hybrid hexagonal/octagonal cellular composite system: Aramid/carbon hybrid composite. Materials & Design. 2014; 63 ():6-13.
Chicago/Turabian StyleE. Mahdi; Tamer Sebaey. 2014. "Crushing behavior of hybrid hexagonal/octagonal cellular composite system: Aramid/carbon hybrid composite." Materials & Design 63, no. : 6-13.
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 crush test was performed under the ambient conditions. The results showed the advantage of laying the woven fiber to 15°/−75° and 75°/−15°, in terms of the pre-crushing loading capacity and the energy absorbed. In addition, by means of visual and the optical microscopy observations, the failure modes of the all the specimens were discussed and categorized.
E. Mahdi; A.M.S. Hamouda; T.A. Sebaey. The effect of fiber orientation on the energy absorption capability of axially crushed composite tubes. Materials & Design 2013, 56, 923 -928.
AMA StyleE. Mahdi, A.M.S. Hamouda, T.A. Sebaey. The effect of fiber orientation on the energy absorption capability of axially crushed composite tubes. Materials & Design. 2013; 56 ():923-928.
Chicago/Turabian StyleE. Mahdi; A.M.S. Hamouda; T.A. Sebaey. 2013. "The effect of fiber orientation on the energy absorption capability of axially crushed composite tubes." Materials & Design 56, no. : 923-928.