The aim of this study is to analyze the effect of different geometries and sections on the mechan... more The aim of this study is to analyze the effect of different geometries and sections on the mechanical properties of epoxy specimens. Five tensile tests were carried out on three types of series. The experimental results obtained were 1812.21 MPa, 3.90% and 41.91 MPa for intact specimens, 1450.41 MPa, 2.16% and 21.28 MPa for specimens with hole and 750.77 MPa, 2.77% and 11.89 MPa for specimens with elliptical -notched for Young's Modulus , strain and stress respectively. In addition, the experimental results indicated that the mechanical properties of both (Young's Modulus value and stress value) were higher in an intact specimen. Afterwards, the nonlinear functional relationship of input parameters between epoxy sample geometries and sections was established using the response surface model (RSM) and the artificial neural network (ANN) to predict the output parameters of mechanical properties (Young's Modulus and stress). In addition, the design of experiment was developed by the Analysis of the Application of Variance (ANOVA). The results showed the superiority of the ANN model over the RSM model, where the correlation coefficient values for the model datasets exceed ANN (R 2 = 0.984 for Young's Modulus and R 2 = 0.981 for the stress).
Journal of Reinforced Plastics and Composites, Mar 15, 2023
This present investigation reports, for the first time, the properties of the polybenzoxazine bio... more This present investigation reports, for the first time, the properties of the polybenzoxazine bio-based furfurylamine reinforced using the hybrid short carbon fibers and tungsten particles. The results revealed good compatibility between the matrix and the filers using scanning electron microscopy, due to the use of the silane treatment that led to enhanced interfacial bonding. In addition, the mechanical data disclosed that the bending and impact values were respectively increased to 210 MPa and 9 KJ/m2 for the composites containing 20%wt of the short carbon fibers and 20%wt tungsten particles. The hybrid composite shielding properties were evaluated using the cobalt-60 as an irradiation source, and the nuclear results depicted that the half-value length and the tenth-value length were increased as compared to those of the pure polymers. Based on the thermal stability studies, the reinforced hybrid composites also showed excellent thermal resistance.
The presence of geometric discontinuity in a material reduces considerably its resistance to mech... more The presence of geometric discontinuity in a material reduces considerably its resistance to mechanical stresses, therefore reducing the service life of materials. The analysis of structural behaviour in the presence of geometric discontinuities is important to ensure the proper use, especially if it is regarding a material of weak mechanical properties such as a polymer. The objective of the present work is to analyse the effect of the notch presence of variable geometric shapes on the tensile strength of epoxy-type polymer specimens. A series of tensile tests were carried out on standardised specimens, taking into account the presence or absence of a notch. Each series of tests contains five specimens. Two notch shapes were considered: circular (hole) and elliptical. The experimental results in terms of stress-strain clearly show that the presence of notches reduces considerably the resistance of the material, where the maximum stress for the undamaged specimen was 41.22 MPa and the lowest stress for the elliptical-notched specimen was 11.21 MPa. A numerical analysis by the extended finite element method (XFEM) was undertaken on the same geometric models; in addition, the results in stress-strain form were validated with the experimental results. A remarkable improvement was obtained (generally an error within 0.06%) for strain, maximum stress, Young's modulus and elongation values. An exponential decrease was noted in the stress, strain, and Young's modulus in the presence of a notch in the material.
This study is mainly focused on the extraction and characterization of the lingo-cellulosic fiber... more This study is mainly focused on the extraction and characterization of the lingo-cellulosic fibers from the Pigeon Pea plant. The chemical components of the fibers such as cellulose content (55.03%), lignin (18.32%), wax content (2.38%), moisture content (8.13%), and density (1.7389 g cc −1) were identified. Functional groups present in the fibers were obtained by infrared spectroscopy. By using X-ray diffraction analysis, Crystallinity Index is found to be 68% and thermogravimetric analysis showed that thermal degradation of the fiber begins at 225°C.The results suggest that the Pigeon pea fibers can be used as reinforcement in polymer-matrix composites. 摘要 本研究主要是从木豆植株中提取和鉴定纤维素纤维。测定了纤维中纤维 素含量(55.03%)、木质素(18.32%)、蜡含量(2.38%)、水分含量 (8.13%)和密度(1.7389g cc_1)等化学成分。通过红外光谱获得纤维 中存在的官能团。通过X-射线衍射分析,发现该纤维的结晶指数为68%,热 重分析表明,该纤维的热降解起始于225°C,表明该纤维可以作为聚合物基复 合材料的增强材料。
ABSTRACT In this work, short carbon fibers were first surface-grafted with various amounts of epo... more ABSTRACT In this work, short carbon fibers were first surface-grafted with various amounts of epoxy terminated hyperbranched polymers, and then utilized as reinforcing phases in various thermosetting polymeric blends composed of dicyanate ester of bisphenol-A (DCBA) and bisphenol-A based benzoxazine (BA-a) resins. The Fourier Transform Infrared Spectroscopy (FTIR) test validated the surface modification of the short fibers and confirmed the reaction between the coated fibers and the DCBA/BA-a resin blend. The composites’ mechanical properties were evaluated and the obtained results revealed that at the maximum fiber loadings, the bending strength and modulus as well as the impact strength were identified to be 217.8 MPa, 7.1 GPa, and 18.4 kJ/m2, respectively. The scanning electron microscope (SEM) analysis established that the enhancements were basically attributed to the good dispersion and adhesion of the coated carbon fibers within the resin matrix. Graphical Abstract
Rotating machines play a strategic role in a manufacturing process; it is the case of a cement mi... more Rotating machines play a strategic role in a manufacturing process; it is the case of a cement mill. These machines are made of fragile organs (bearings and gears, etc.) subjected to significant mechanical stresses and harsh industrial environments. Improving productivity through better control of the production tool through its automation, although by controlling its availability; automation must be associated with a maintenance strategy that will ensure a more availability. However, many techniques available currently require much expertise to successfully implement; it requires new techniques that allow relatively unskilled operators to make reliable decisions without knowing the mechanism of system and analyzing the data. The artificial neural networks (ANN) are suitable for this type of problem diagnosis using the classification method. This article discusses the automation of isolated diagnosis faults of bearings and gears in a gear unit DMGH25.4 of cement mill by coupling spectral analysis vibration-neural networks.
Rotating machines play a strategic role in a manufacturing process, and it is the case of a cemen... more Rotating machines play a strategic role in a manufacturing process, and it is the case of a cement mill. These machines are composed of fragile bodies (bearings and gears, etc.) subjected to mechanical stress and harsh industrial environment.Sources of failure are many; the wear and the spalling of bearing, the wear and fracture of a tooth of a gear, the misalignment of the axes, etc. To avoid unexpected downtime and costly, those bodies must be monitored continuously. There are several ways to do that; vibration analysis, lubricant analysis, infrared thermography and acoustic analysis. Vibration analysis (frequency) is most often used by operating a signal from an accelerometer. Whenever a fault participated in a contact, it changed the vibration characteristics of the system. By analyzing the acceleration measurements from an accelerometer, we can identify and quantify these changes in order to establish a relationship between the measures and the type of defect, which will be use...
The welds are the site of high residual stresses, localized in the vicinity of the weld cracks. T... more The welds are the site of high residual stresses, localized in the vicinity of the weld cracks. Their presence caused many type of damage mode as stress corrosion, fatigue, sudden failure and increasing the temperature of ductile/brittle transition. Residual stresses in restrained welds and weld repairs are very complex. The heat treatment affects the value and distribution of residual stress in the specimen. This peak stress in all three samples occurred not at the toe, but in the middle of the weld bead, where the yield stress is higher. The use of the neutron diffraction (ND) technique for residual stress measurements is described. In addition, studies of macrostructure and hardness were conducted. The results of different tests conclude the influence of heat treatment on Residual stresses in welds.
Journal of the Serbian Society for Computational Mechanics
This article focuses on the design and manufacture of mechanical parts that have complicated shap... more This article focuses on the design and manufacture of mechanical parts that have complicated shapes using the technique of reverse design using a scanner or an MMT for data acquisition in the form of a point cloud, using CAD software (CATIA). The digital model created is used for a virtual representation of the final product. Then we get the physical model on a 3D printer (also called additive manufacturing process) for later use in sand moulds. To have the imprint in the sand mould, we go through the fusion of the physical model (part). The use of this technique in the industry, allows us to save a lot of time in terms of model preparation and simple to implement, especially if it is mechanical parts that do not have a definition drawing, or they are worn out, then structural analysis was applied on the model using FE based software and tools to prove the quality of the product. Von Mises equivalent strains and stresses were predicted and decreased with increasing areas and honeyco...
The present investigation aimed to understand the physicochemical properties of the new cellulosi... more The present investigation aimed to understand the physicochemical properties of the new cellulosic fiber extracted from the bark of Silybum marianum (SM), in view of using it as a potential reinforcement for polymer composites. The morphological and anatomy, physical, thermal and mechanical properties of fibers were firstly discussed in this paper. The Silybum marianum fibers (SMF) were characterized by scanning electron microscopy, Fourier transform infrared, thermogravimetric analysis (TGA), optical microscope, X-ray diffraction (XRD), and single fiber tensile test. The average Young’s modulus and the breaking stress data presented by the fibers are 15.97 GPa and 201.16 MPa, respectively. XRD reveals the presence of cellulose with a crystallinity index of 45%. Thermal stability (250°C) and maximum degradation temperature (357.72°C) of the SMF are established by the thermogravimetric analysis. An analysis of the mechanical properties was carried out on a population of 35 samples us...
The effect of a pre (before) and post (after) heating welding treatment on the microstructure and... more The effect of a pre (before) and post (after) heating welding treatment on the microstructure and mechanical properties of the scrap blades made of cast INC738LC superalloy is the main goal of the present investigation. The filler used in TIG welding was a INC 625 solution hardened superalloy as the proposed solution for hot cracking of the INC738LC cast superalloy in literature. The TIG welding was processed with respect to the constantly optimized parameters (current, voltage, speed, gas flux rate and number of passes) to make a mechanical properties comparison between the as received superalloy and the welded superalloy with heat treated specimens. The characterization techniques employed in this study are hardness measurements, tensile tests, optical microscopy and scanning electron microscopy. We found that the proposed preheating improves the TIG welding of the INC 738 LC superalloy specimens and the post welding heat treatment enhances its mechanical properties.
This study concerns the wear behaviour of metal couples used in industry, particularly in mechani... more This study concerns the wear behaviour of metal couples used in industry, particularly in mechanical sliding systems (numerically controlled machine tools). In general, the nature of the materials of the parts of these systems which are in contact and move relatively, are medium carbon steels, thanks to their good mechanical and tribological properties. The present work aims to study, the dry sliding wear of the contact surface of the pin (machine slide) against the contact surface of a disc (machine groove) and the damage induced on the worn track. The pin is AISI 1038 and AISI 1045 steel, the disc is AISI 1055 steel. The tribological tests were carried out on a pin-disc tribometer, in an atmospheric environment. The wear of the pins being evaluated by weighing and studied according to the hardness of the pin with the variation of the normal load applied. The discussion of the results is based on SEM observations and EDS analyzes of worn surfaces and interfacial phenomena produced by dynamic contact. The results obtained indicated the influence of the applied load and the hardness on the wear of the pin and therefore on the tribological behaviour of the worn surfaces.
The balancing operation consists in improving the distribution of the rotor masses so that the fr... more The balancing operation consists in improving the distribution of the rotor masses so that the free centrifugal forces around the rotor axis, imposed by the manufacturer, do not exceed the tolerances allowed by the standards. In this paper we propose algorithms for the distribution of the turbine blades from data from an electronic scale which allows to measure the static moment of the blades, these algorithms aim to find the correction weight and the angle of position of the correction mass, we also propose a simulation of the distribution of the blades of a turbine to get an idea on the assembly. This operation is necessary in the case of a repair of the rotors or in the assembly of the new flexible rotors. Using a MATLAB calculation code.
The aim of this study is to analyze the effect of different geometries and sections on the mechan... more The aim of this study is to analyze the effect of different geometries and sections on the mechanical properties of epoxy specimens. Five tensile tests were carried out on three types of series. The experimental results obtained were 1812.21 MPa, 3.90% and 41.91 MPa for intact specimens, 1450.41 MPa, 2.16% and 21.28 MPa for specimens with hole and 750.77 MPa, 2.77% and 11.89 MPa for specimens with elliptical -notched for Young's Modulus , strain and stress respectively. In addition, the experimental results indicated that the mechanical properties of both (Young's Modulus value and stress value) were higher in an intact specimen. Afterwards, the nonlinear functional relationship of input parameters between epoxy sample geometries and sections was established using the response surface model (RSM) and the artificial neural network (ANN) to predict the output parameters of mechanical properties (Young's Modulus and stress). In addition, the design of experiment was developed by the Analysis of the Application of Variance (ANOVA). The results showed the superiority of the ANN model over the RSM model, where the correlation coefficient values for the model datasets exceed ANN (R 2 = 0.984 for Young's Modulus and R 2 = 0.981 for the stress).
Journal of Reinforced Plastics and Composites, Mar 15, 2023
This present investigation reports, for the first time, the properties of the polybenzoxazine bio... more This present investigation reports, for the first time, the properties of the polybenzoxazine bio-based furfurylamine reinforced using the hybrid short carbon fibers and tungsten particles. The results revealed good compatibility between the matrix and the filers using scanning electron microscopy, due to the use of the silane treatment that led to enhanced interfacial bonding. In addition, the mechanical data disclosed that the bending and impact values were respectively increased to 210 MPa and 9 KJ/m2 for the composites containing 20%wt of the short carbon fibers and 20%wt tungsten particles. The hybrid composite shielding properties were evaluated using the cobalt-60 as an irradiation source, and the nuclear results depicted that the half-value length and the tenth-value length were increased as compared to those of the pure polymers. Based on the thermal stability studies, the reinforced hybrid composites also showed excellent thermal resistance.
The presence of geometric discontinuity in a material reduces considerably its resistance to mech... more The presence of geometric discontinuity in a material reduces considerably its resistance to mechanical stresses, therefore reducing the service life of materials. The analysis of structural behaviour in the presence of geometric discontinuities is important to ensure the proper use, especially if it is regarding a material of weak mechanical properties such as a polymer. The objective of the present work is to analyse the effect of the notch presence of variable geometric shapes on the tensile strength of epoxy-type polymer specimens. A series of tensile tests were carried out on standardised specimens, taking into account the presence or absence of a notch. Each series of tests contains five specimens. Two notch shapes were considered: circular (hole) and elliptical. The experimental results in terms of stress-strain clearly show that the presence of notches reduces considerably the resistance of the material, where the maximum stress for the undamaged specimen was 41.22 MPa and the lowest stress for the elliptical-notched specimen was 11.21 MPa. A numerical analysis by the extended finite element method (XFEM) was undertaken on the same geometric models; in addition, the results in stress-strain form were validated with the experimental results. A remarkable improvement was obtained (generally an error within 0.06%) for strain, maximum stress, Young's modulus and elongation values. An exponential decrease was noted in the stress, strain, and Young's modulus in the presence of a notch in the material.
This study is mainly focused on the extraction and characterization of the lingo-cellulosic fiber... more This study is mainly focused on the extraction and characterization of the lingo-cellulosic fibers from the Pigeon Pea plant. The chemical components of the fibers such as cellulose content (55.03%), lignin (18.32%), wax content (2.38%), moisture content (8.13%), and density (1.7389 g cc −1) were identified. Functional groups present in the fibers were obtained by infrared spectroscopy. By using X-ray diffraction analysis, Crystallinity Index is found to be 68% and thermogravimetric analysis showed that thermal degradation of the fiber begins at 225°C.The results suggest that the Pigeon pea fibers can be used as reinforcement in polymer-matrix composites. 摘要 本研究主要是从木豆植株中提取和鉴定纤维素纤维。测定了纤维中纤维 素含量(55.03%)、木质素(18.32%)、蜡含量(2.38%)、水分含量 (8.13%)和密度(1.7389g cc_1)等化学成分。通过红外光谱获得纤维 中存在的官能团。通过X-射线衍射分析,发现该纤维的结晶指数为68%,热 重分析表明,该纤维的热降解起始于225°C,表明该纤维可以作为聚合物基复 合材料的增强材料。
ABSTRACT In this work, short carbon fibers were first surface-grafted with various amounts of epo... more ABSTRACT In this work, short carbon fibers were first surface-grafted with various amounts of epoxy terminated hyperbranched polymers, and then utilized as reinforcing phases in various thermosetting polymeric blends composed of dicyanate ester of bisphenol-A (DCBA) and bisphenol-A based benzoxazine (BA-a) resins. The Fourier Transform Infrared Spectroscopy (FTIR) test validated the surface modification of the short fibers and confirmed the reaction between the coated fibers and the DCBA/BA-a resin blend. The composites’ mechanical properties were evaluated and the obtained results revealed that at the maximum fiber loadings, the bending strength and modulus as well as the impact strength were identified to be 217.8 MPa, 7.1 GPa, and 18.4 kJ/m2, respectively. The scanning electron microscope (SEM) analysis established that the enhancements were basically attributed to the good dispersion and adhesion of the coated carbon fibers within the resin matrix. Graphical Abstract
Rotating machines play a strategic role in a manufacturing process; it is the case of a cement mi... more Rotating machines play a strategic role in a manufacturing process; it is the case of a cement mill. These machines are made of fragile organs (bearings and gears, etc.) subjected to significant mechanical stresses and harsh industrial environments. Improving productivity through better control of the production tool through its automation, although by controlling its availability; automation must be associated with a maintenance strategy that will ensure a more availability. However, many techniques available currently require much expertise to successfully implement; it requires new techniques that allow relatively unskilled operators to make reliable decisions without knowing the mechanism of system and analyzing the data. The artificial neural networks (ANN) are suitable for this type of problem diagnosis using the classification method. This article discusses the automation of isolated diagnosis faults of bearings and gears in a gear unit DMGH25.4 of cement mill by coupling spectral analysis vibration-neural networks.
Rotating machines play a strategic role in a manufacturing process, and it is the case of a cemen... more Rotating machines play a strategic role in a manufacturing process, and it is the case of a cement mill. These machines are composed of fragile bodies (bearings and gears, etc.) subjected to mechanical stress and harsh industrial environment.Sources of failure are many; the wear and the spalling of bearing, the wear and fracture of a tooth of a gear, the misalignment of the axes, etc. To avoid unexpected downtime and costly, those bodies must be monitored continuously. There are several ways to do that; vibration analysis, lubricant analysis, infrared thermography and acoustic analysis. Vibration analysis (frequency) is most often used by operating a signal from an accelerometer. Whenever a fault participated in a contact, it changed the vibration characteristics of the system. By analyzing the acceleration measurements from an accelerometer, we can identify and quantify these changes in order to establish a relationship between the measures and the type of defect, which will be use...
The welds are the site of high residual stresses, localized in the vicinity of the weld cracks. T... more The welds are the site of high residual stresses, localized in the vicinity of the weld cracks. Their presence caused many type of damage mode as stress corrosion, fatigue, sudden failure and increasing the temperature of ductile/brittle transition. Residual stresses in restrained welds and weld repairs are very complex. The heat treatment affects the value and distribution of residual stress in the specimen. This peak stress in all three samples occurred not at the toe, but in the middle of the weld bead, where the yield stress is higher. The use of the neutron diffraction (ND) technique for residual stress measurements is described. In addition, studies of macrostructure and hardness were conducted. The results of different tests conclude the influence of heat treatment on Residual stresses in welds.
Journal of the Serbian Society for Computational Mechanics
This article focuses on the design and manufacture of mechanical parts that have complicated shap... more This article focuses on the design and manufacture of mechanical parts that have complicated shapes using the technique of reverse design using a scanner or an MMT for data acquisition in the form of a point cloud, using CAD software (CATIA). The digital model created is used for a virtual representation of the final product. Then we get the physical model on a 3D printer (also called additive manufacturing process) for later use in sand moulds. To have the imprint in the sand mould, we go through the fusion of the physical model (part). The use of this technique in the industry, allows us to save a lot of time in terms of model preparation and simple to implement, especially if it is mechanical parts that do not have a definition drawing, or they are worn out, then structural analysis was applied on the model using FE based software and tools to prove the quality of the product. Von Mises equivalent strains and stresses were predicted and decreased with increasing areas and honeyco...
The present investigation aimed to understand the physicochemical properties of the new cellulosi... more The present investigation aimed to understand the physicochemical properties of the new cellulosic fiber extracted from the bark of Silybum marianum (SM), in view of using it as a potential reinforcement for polymer composites. The morphological and anatomy, physical, thermal and mechanical properties of fibers were firstly discussed in this paper. The Silybum marianum fibers (SMF) were characterized by scanning electron microscopy, Fourier transform infrared, thermogravimetric analysis (TGA), optical microscope, X-ray diffraction (XRD), and single fiber tensile test. The average Young’s modulus and the breaking stress data presented by the fibers are 15.97 GPa and 201.16 MPa, respectively. XRD reveals the presence of cellulose with a crystallinity index of 45%. Thermal stability (250°C) and maximum degradation temperature (357.72°C) of the SMF are established by the thermogravimetric analysis. An analysis of the mechanical properties was carried out on a population of 35 samples us...
The effect of a pre (before) and post (after) heating welding treatment on the microstructure and... more The effect of a pre (before) and post (after) heating welding treatment on the microstructure and mechanical properties of the scrap blades made of cast INC738LC superalloy is the main goal of the present investigation. The filler used in TIG welding was a INC 625 solution hardened superalloy as the proposed solution for hot cracking of the INC738LC cast superalloy in literature. The TIG welding was processed with respect to the constantly optimized parameters (current, voltage, speed, gas flux rate and number of passes) to make a mechanical properties comparison between the as received superalloy and the welded superalloy with heat treated specimens. The characterization techniques employed in this study are hardness measurements, tensile tests, optical microscopy and scanning electron microscopy. We found that the proposed preheating improves the TIG welding of the INC 738 LC superalloy specimens and the post welding heat treatment enhances its mechanical properties.
This study concerns the wear behaviour of metal couples used in industry, particularly in mechani... more This study concerns the wear behaviour of metal couples used in industry, particularly in mechanical sliding systems (numerically controlled machine tools). In general, the nature of the materials of the parts of these systems which are in contact and move relatively, are medium carbon steels, thanks to their good mechanical and tribological properties. The present work aims to study, the dry sliding wear of the contact surface of the pin (machine slide) against the contact surface of a disc (machine groove) and the damage induced on the worn track. The pin is AISI 1038 and AISI 1045 steel, the disc is AISI 1055 steel. The tribological tests were carried out on a pin-disc tribometer, in an atmospheric environment. The wear of the pins being evaluated by weighing and studied according to the hardness of the pin with the variation of the normal load applied. The discussion of the results is based on SEM observations and EDS analyzes of worn surfaces and interfacial phenomena produced by dynamic contact. The results obtained indicated the influence of the applied load and the hardness on the wear of the pin and therefore on the tribological behaviour of the worn surfaces.
The balancing operation consists in improving the distribution of the rotor masses so that the fr... more The balancing operation consists in improving the distribution of the rotor masses so that the free centrifugal forces around the rotor axis, imposed by the manufacturer, do not exceed the tolerances allowed by the standards. In this paper we propose algorithms for the distribution of the turbine blades from data from an electronic scale which allows to measure the static moment of the blades, these algorithms aim to find the correction weight and the angle of position of the correction mass, we also propose a simulation of the distribution of the blades of a turbine to get an idea on the assembly. This operation is necessary in the case of a repair of the rotors or in the assembly of the new flexible rotors. Using a MATLAB calculation code.
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Papers by Moussa ZAOUI