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This research work focuses on evaluating the suitability of agricultural waste natural fibre namely rice, wheat and mustard as sustainable bio-composite that can also be used as an acoustic absorber for industrial noise control. Rice straw pulp was used in this method, pulp was extracted from rice straw then it was combined with binders to form bio composites. It was then tested for different properties. Porosity is highest when rice straw pulp was mixed with natural binders (starch). Hardness and thermal resistance was observed maximum in products made using cement and lime binders and moisture content was found maximum in composites made from natural binders. This means that composites made from rice straw pulp with natural binders has better sound absorption capacity as compared to those made using synthetic binders but composites with synthetic binders have better hardness. Products made from these methods can be used for biomedical, automobiles, packaging, acoustics and other engineering applications.
Anam Fatima; Navira Qayyum; Mohd Zaid; Yasser Rafat; Mohammad Zain Khan; Rashid Ali; Bashmal Salem. Feasibility of manufacturing sustainable bio-composites from agricultural waste. Materials Today: Proceedings 2021, 1 .
AMA StyleAnam Fatima, Navira Qayyum, Mohd Zaid, Yasser Rafat, Mohammad Zain Khan, Rashid Ali, Bashmal Salem. Feasibility of manufacturing sustainable bio-composites from agricultural waste. Materials Today: Proceedings. 2021; ():1.
Chicago/Turabian StyleAnam Fatima; Navira Qayyum; Mohd Zaid; Yasser Rafat; Mohammad Zain Khan; Rashid Ali; Bashmal Salem. 2021. "Feasibility of manufacturing sustainable bio-composites from agricultural waste." Materials Today: Proceedings , no. : 1.
Several approaches have been used in the past to predict fatigue crack growth rates in T-joints of the offshore structures, but there are relatively few cases of applying structural health monitoring during the non-destructive testing of jacket platforms. This paper presents an experimental method based on the sensing of the piezoelectric sensors and finite element analysis method for studying the fatigue cracks in the offshore steel jacket structure. Three types of joints are selected in the current research work: T-type plate, T-type tube-plate, and T-type tube joints. The finite element analysis model established in the current study computes and analyzes the high stress and high strain regions in the T-type joints. The fatigue damage in the T-type joints was successfully detected by utilizing both the finite element analysis and experimental methods. The results showed that fatigue cracks of the three types of joints are prone to appear at the weld toe and spread in the welding direction. The fatigue damage location of T-type plate and T-type tube-plate joints is more concentrated in the upper weld toe area, and the fatigue damage location of the T-type tube joint is closer to the lower weld toe area.
Liaqat Ali; Sikandar Khan; Salem Bashmal; Naveed Iqbal; Weishun Dai; Yong Bai. Fatigue Crack Monitoring of T-Type Joints in Steel Offshore Oil and Gas Jacket Platform. Sensors 2021, 21, 3294 .
AMA StyleLiaqat Ali, Sikandar Khan, Salem Bashmal, Naveed Iqbal, Weishun Dai, Yong Bai. Fatigue Crack Monitoring of T-Type Joints in Steel Offshore Oil and Gas Jacket Platform. Sensors. 2021; 21 (9):3294.
Chicago/Turabian StyleLiaqat Ali; Sikandar Khan; Salem Bashmal; Naveed Iqbal; Weishun Dai; Yong Bai. 2021. "Fatigue Crack Monitoring of T-Type Joints in Steel Offshore Oil and Gas Jacket Platform." Sensors 21, no. 9: 3294.
The release of large quantities of CO2 into the atmosphere is one of the major causes of global warming. The most viable method to control the level of CO2 in the atmosphere is to capture and permanently sequestrate the excess amount of CO2 in subsurface geological reservoirs. The injection of CO2 gives rise to pore pressure buildup. It is crucial to monitor the rising pore pressure in order to prevent the potential failure of the reservoir and the subsequent leakage of the stored CO2 into the overburden layers, and then back to the atmosphere. In this paper, the Minjur sandstone reservoir in eastern Saudi Arabia was considered for establishing a coupled geomechanical model and performing the corresponding stability analysis. During the geomechanical modeling process, the fault passing through the Minjur and Marrat layers was also considered. The injection-induced pore-pressure and ground uplift profiles were calculated for the case of absence of a fault across the reservoir, as well as the case with a fault. The stability analysis was performed using the Mohr–Coulomb failure criterion. In the current study, the excessive increase in pore pressure, in the absence of geological faults, moved the reservoir closer to the failure envelope, but in the presence of geological faults, the reservoir reached to the failure envelope and the faults were activated. The developed geomechanical model provided estimates for the safe injection parameters of CO2 based on the magnitudes of the reservoir pore pressure and stresses in the reservoir.
Sikandar Khan; Yehia Khulief; Abdullatif Al-Shuhail; Salem Bashmal; Naveed Iqbal. The Geomechanical and Fault Activation Modeling during CO2 Injection into Deep Minjur Reservoir, Eastern Saudi Arabia. Sustainability 2020, 12, 9800 .
AMA StyleSikandar Khan, Yehia Khulief, Abdullatif Al-Shuhail, Salem Bashmal, Naveed Iqbal. The Geomechanical and Fault Activation Modeling during CO2 Injection into Deep Minjur Reservoir, Eastern Saudi Arabia. Sustainability. 2020; 12 (23):9800.
Chicago/Turabian StyleSikandar Khan; Yehia Khulief; Abdullatif Al-Shuhail; Salem Bashmal; Naveed Iqbal. 2020. "The Geomechanical and Fault Activation Modeling during CO2 Injection into Deep Minjur Reservoir, Eastern Saudi Arabia." Sustainability 12, no. 23: 9800.
The paper presents an investigation and analysis of the electromechanical and thermal characteristics of the carbon fiber alone as single tow and embedded in host materials such as polymer e.g., acrylonitrile butadiene styrene (ABS) using 3D printing. While carbon fibers can partially reinforce the structure, they can act as sensors to monitor the structural health of the host material. The piezo-resistive behavior was examined without any pretreatment of the carbon fiber under tensile test in both cases. Special focus on the filaments clamping types and their effects was observed. An auxetic behavior was exhibited; otherwise, the free part shows elastic and yielding ranges with break point at high resistance. An induced temperature of the carbon fiber was measured during the tensile test to show low variation. The carbon fiber can provide strength contribution to the host material depending on the percentage of filling the material in 3D printing. The relative variation of the electrical resistance increases by 400% while embedded in the host material, but decreases as the tows filament density increases from 1 to 12 K.
Samir Mekid; Hammam Daraghma; Salem Bashmal. Electromechanical Assessment and Induced Temperature Measurement of Carbon Fiber Tows under Tensile Condition. Materials 2020, 13, 4234 .
AMA StyleSamir Mekid, Hammam Daraghma, Salem Bashmal. Electromechanical Assessment and Induced Temperature Measurement of Carbon Fiber Tows under Tensile Condition. Materials. 2020; 13 (19):4234.
Chicago/Turabian StyleSamir Mekid; Hammam Daraghma; Salem Bashmal. 2020. "Electromechanical Assessment and Induced Temperature Measurement of Carbon Fiber Tows under Tensile Condition." Materials 13, no. 19: 4234.
The sensitivity analysis using normalized sensitivity coefficient (NSC) can be used to identify important model parameters affecting the device performance by allowing one-to-one comparison. The results are highlighted in the form of order of magnitudes change in output for a unit change in input variable. In this study, the sensitivity analysis of a small capacity standing wave thermoacoustic refrigerator (SWTAR) has been performed using NSC. Specialized tool deltaec has been used to generate the results for the subsequent sensitivity analysis. Three key performance parameters, i.e., temperature difference achieved (ΔT), coefficient of performance (COP), and relative coefficient of performance (COPR) have been analyzed for perturbations in number of device variables, namely, oscillating pressure amplitude, two different stack material properties and four stack geometric parameters, i.e., stack length, stack center position, stack plate thickness, and half stack spacing. Sensitivity results are obtained for a wide range of mean operating pressures (Pm), mean operating temperature (Tm), and drive ratios (DRs). It has been found that performance parameters are most sensitive to the perturbations in oscillating pressure amplitude and least affected by the perturbations in the stack length. With respect to the oscillating pressure amplitude, maximum NSC of 24.12 has been reported for ΔT at mean pressure of 5 bar.
Umar Nawaz Bhatti; Salem Bashmal. Performance Evaluation of a Standing Wave Thermoacoustic Refrigerator Using Normalized Sensitivity Coefficients. Journal of Thermal Science and Engineering Applications 2020, 13, 1 -35.
AMA StyleUmar Nawaz Bhatti, Salem Bashmal. Performance Evaluation of a Standing Wave Thermoacoustic Refrigerator Using Normalized Sensitivity Coefficients. Journal of Thermal Science and Engineering Applications. 2020; 13 (3):1-35.
Chicago/Turabian StyleUmar Nawaz Bhatti; Salem Bashmal. 2020. "Performance Evaluation of a Standing Wave Thermoacoustic Refrigerator Using Normalized Sensitivity Coefficients." Journal of Thermal Science and Engineering Applications 13, no. 3: 1-35.
Thermoacoustic refrigerators have huge potential to replace conventional refrigeration systems as an alternative clean refrigeration technology. These devices utilize conversion of acoustic power and heat energy to generate the desired cooling. The stack plays a pivotal role in the performance of Standing Wave Thermoacoustic Refrigerators (SWTARs), as the heat transfer takes place across it. Performance of stacks can be significantly improved by making an arrangement of different materials inside the stack, resulting in anisotropic thermal properties along the length. In the present numerical study, the effect of multi-layered stack on the refrigeration performance of a SWTAR has been evaluated in terms of temperature drop across the stack, acoustic power consumed and device Coefficient of Performance (COP). Two different aspects of multi-layered stack, namely, different material combinations and different lengths of stacked layers, have been investigated. The combinations of four stack materials and length ratios have been investigated. The numerical results showed that multi-layered stacks produce lower refrigeration temperatures, consume less energy and have higher COP value than their homogeneous counterparts. Among all the material combinations of multi-layered stack investigated, stacks composed of a material layer with low thermal conductivity at the ends, i.e., RVC, produced the best performance with an increase of 26.14% in temperature drop value, reduction in the acoustic power consumption by 4.55% and COP enhancement of 5.12%. The results also showed that, for a constant overall length, an increase in length of side stacked material layer results in an increase in values of both temperature drop and COP.
Umar Nawaz Bhatti; Salem Bashmal; Sikandar Khan; Rached Ben-Mansour. Numerical Modeling and Performance Evaluation of Standing Wave Thermoacoustic Refrigerators with a Multi-Layered Stack. Energies 2020, 13, 4360 .
AMA StyleUmar Nawaz Bhatti, Salem Bashmal, Sikandar Khan, Rached Ben-Mansour. Numerical Modeling and Performance Evaluation of Standing Wave Thermoacoustic Refrigerators with a Multi-Layered Stack. Energies. 2020; 13 (17):4360.
Chicago/Turabian StyleUmar Nawaz Bhatti; Salem Bashmal; Sikandar Khan; Rached Ben-Mansour. 2020. "Numerical Modeling and Performance Evaluation of Standing Wave Thermoacoustic Refrigerators with a Multi-Layered Stack." Energies 13, no. 17: 4360.
Treated herein is an elastic beam that is subjected to a constant load that travels continuously (back and forth) along its span. The dynamic deflection of the beam is investigated analytically so as to predict the critical and cancellation speeds. Closed-form solutions are obtained for the damped system for each load condition and superimposed to determine the total solution of the response. Unlike the classical case of load traveling at constant speed in one direction, multiple resonance peaks are observed for reciprocating load at speeds that are lower than the classical critical speed. It is also observed that resonance may not exist at the classical critical speed for simply supported beams due to the symmetry of the beam. The dynamic deflection is examined for simply supported beams to determine the speeds that cause amplification or cancellation of the free response. The current load condition may have possible application in view of its potential use for vibration suppression, as a moving vibration absorber, or for magnification, in energy harvesting. The results are interpreted in order to understand the variation of dynamic deflection and to estimate the critical speeds for different load conditions.
Salem Bashmal. Determination of Critical and Cancellation Speeds of Euler–Bernoulli Beam Subject to a Continuously Moving Load. International Journal of Structural Stability and Dynamics 2019, 19, 1 .
AMA StyleSalem Bashmal. Determination of Critical and Cancellation Speeds of Euler–Bernoulli Beam Subject to a Continuously Moving Load. International Journal of Structural Stability and Dynamics. 2019; 19 (3):1.
Chicago/Turabian StyleSalem Bashmal. 2019. "Determination of Critical and Cancellation Speeds of Euler–Bernoulli Beam Subject to a Continuously Moving Load." International Journal of Structural Stability and Dynamics 19, no. 3: 1.
Purpose Novel nanomaterials and nano-devices require further functional aspects that can be designed and supported using new nanomanipulation techniques allowing specific functions at the design phase. The nano-manipulator becomes a key instrument for technology bridging sub-nano to mesoscale. The integration of various operations in nano-devices requires sub-nanometer precision and highly stable manipulator. This paper aims to review various design concepts of recent nanomanipulators, their motion characteristics, basic functions, imagine and automation with control techniques for the sake of establishing new design features based on recent requirements. Design/methodology/approach The paper reviews various existing nanomanipulators, their motion characteristics, basic functions, imagine and automation with control techniques. This will support precision machine design methodology and robotics principles. Findings The availability of a nano-precision instrument with integrated functions has proved to be extremely helpful in addressing various fundamental problems in science and engineering such as exploring, understanding, modeling and testing nano-machining process; exact construction of nano-structure arrays; and inspection of devices with complex features. Originality/value New functional specifications have emerged from this review to support the design and make of new advanced nanomanipulators with more features availability to support manipulation within the same reference datum needed for research and education.
Samir Mekid; Salem Bashmal. Engineering manipulation at nanoscale: further functional specifications. Journal of Engineering, Design and Technology 2019, 17, 572 -590.
AMA StyleSamir Mekid, Salem Bashmal. Engineering manipulation at nanoscale: further functional specifications. Journal of Engineering, Design and Technology. 2019; 17 (3):572-590.
Chicago/Turabian StyleSamir Mekid; Salem Bashmal. 2019. "Engineering manipulation at nanoscale: further functional specifications." Journal of Engineering, Design and Technology 17, no. 3: 572-590.
Carbon fiber-based materials possess excellent mechanical properties and show linear piezoresistive behavior, which make them good candidate materials for strain measurements. They have the potential to be used as sensors for various applications such as damage detection, stress analysis and monitoring of manufacturing processes and quality. In this paper, carbon fiber sensors are prepared to perform reliable strain measurements. Both experimental and computational studies were carried out on commercially available carbon fibers in order to understand the response of the carbon fiber sensors due to changes in the axial strain. Effects of parameters such as diameter, length, and epoxy-hardener ratio are discussed. The developed numerical model was calibrated using laboratory-based experimental data. The results of the current study show that sensors with shorter lengths have relatively better sensitivity. This is due to the fact short fibers have low initial resistance, which will increase the change of resistance over initial resistance. Carbon fibers with low number of filaments exhibit linear behavior while nonlinear behavior due to transverse resistance is significant in fibers with large number of filaments. This study will allow researchers to predict the behavior of the carbon fiber sensor in real life and it will serve as a basis for designing carbon fiber sensors to be used in different applications.
Salem Bashmal; Mohammed Siddiqui; Abul Fazal M. Arif. Experimental and Numerical Investigations on the Mechanical Characteristics of Carbon Fiber Sensors. Sensors 2017, 17, 2026 .
AMA StyleSalem Bashmal, Mohammed Siddiqui, Abul Fazal M. Arif. Experimental and Numerical Investigations on the Mechanical Characteristics of Carbon Fiber Sensors. Sensors. 2017; 17 (9):2026.
Chicago/Turabian StyleSalem Bashmal; Mohammed Siddiqui; Abul Fazal M. Arif. 2017. "Experimental and Numerical Investigations on the Mechanical Characteristics of Carbon Fiber Sensors." Sensors 17, no. 9: 2026.
We present a modeling approach to determine the permeability-selectivity tradeoff for microfiltration and ultrafiltration membranes with a distribution of pore sizes and pore shapes. Using the formulated permeability-selectivity model, the effect of pore aspect ratio and pore size distribution on the permeability-selectivity tradeoff of the membrane is analyzed. A finite element model is developed to study the effect of membrane stretching on the distribution of pore sizes and shapes in the stretched membrane. The effect of membrane stretching on the permeability-selectivity tradeoff of membranes is also analyzed. The results show that increasing pore aspect ratio improves membrane performance while increasing the width of pore size distribution deteriorates the performance. It was also found that the effect of membrane stretching on the permeability-selectivity tradeoff is greatly affected by the uniformity of pore distribution in the membrane. Stretching showed a positive shift in the permeability-selectivity tradeoff curve of membranes with well-dispersed pores while in the case of pore clustering, a negative shift in the permeability-selectivity tradeoff curve was observed.
Muhammad Usama Siddiqui; Abul Fazal Muhammad Arif; Salem Bashmal. Permeability-Selectivity Analysis of Microfiltration and Ultrafiltration Membranes: Effect of Pore Size and Shape Distribution and Membrane Stretching. Membranes 2016, 6, 40 .
AMA StyleMuhammad Usama Siddiqui, Abul Fazal Muhammad Arif, Salem Bashmal. Permeability-Selectivity Analysis of Microfiltration and Ultrafiltration Membranes: Effect of Pore Size and Shape Distribution and Membrane Stretching. Membranes. 2016; 6 (3):40.
Chicago/Turabian StyleMuhammad Usama Siddiqui; Abul Fazal Muhammad Arif; Salem Bashmal. 2016. "Permeability-Selectivity Analysis of Microfiltration and Ultrafiltration Membranes: Effect of Pore Size and Shape Distribution and Membrane Stretching." Membranes 6, no. 3: 40.
Numerical and experimental investigations are carried out to study the combined effect of rotation and support nonuniformity on the modal characteristics of circular thick disks. The laboratory experiments on stationary and rotating circular disks are conducted to investigate the effects of partial support conditions on the in-plane and out-of-plane vibration responses of annular disks with different radius ratios. Numerical results suggested that the nonuniformity of the support along the circumferential directions of the boundaries affects the modal characteristics of the disk along the in-plane and out-of-plane directions, while introducing additional coupling between the modes. Specifically, some of the frequency peaks in the frequency spectrum obtained under uniform boundary conditions split into two distinct peaks in the presence of a point support. The results show that the in-plane modes of vibration are comparable with those associated with out-of-plane modes and are contributing to the total noise radiation. The coupling between in-plane and out-of-plane modes is found to be quite significant due to the nonuniformity of the boundary conditions. The experimental study confirms the split in natural frequencies of the disk that is observed in the numerical results due to both rotation and support nonuniformity. The applicability and accuracy of the formulations is further examined through analysis of modal characteristics of a railway wheel in contact with the rail.
Salem Bashmal; Rama Bhat; Subhash Rakheja. Experimental and Numerical Study of the Vibration of Stationary and Rotating Annular Disks. Journal of Vibration and Acoustics 2016, 138, 051003 .
AMA StyleSalem Bashmal, Rama Bhat, Subhash Rakheja. Experimental and Numerical Study of the Vibration of Stationary and Rotating Annular Disks. Journal of Vibration and Acoustics. 2016; 138 (5):051003.
Chicago/Turabian StyleSalem Bashmal; Rama Bhat; Subhash Rakheja. 2016. "Experimental and Numerical Study of the Vibration of Stationary and Rotating Annular Disks." Journal of Vibration and Acoustics 138, no. 5: 051003.
Background: Nanomanipulation techniques have gone through several phases to be used in scientific explorations not only to reveal more characteristics of nano, micro and mesoscopic phenomena but also to build functional nano-devices useful for specific applications. The nano-manipulator becomes a key instrument for technology bridging between sub-nano and mesoscale. The recent patents have exhibited integration of various functions in the nano-devices requiring sub-nanometer precision and highly stable manipulator with substantial pulling/pushing forces. This work reviews patents and works on conceptual designs of existing nanomanipulators with specific features. This includes design analysis leading to ultra-precision motion and stability with discussion of enabling technology. A novel integrated and numerically controlled instrument for nanomanipulation, visualization and inspection/characterization of materials at sub-nanoscale will be presented with a feature to keep the same datum for all operation and hence improve accuracy of samples. Methods: This paper has undertaken a review search in a structured examination of bibliographic databases for published and issued patents using a focused review keyword of nano-manipulation. The quality of selected patents was appraised using standard tools. The characteristics of screened patents were described, and a deductive qualitative content analysis methodology was applied to understand the modeling and testing of nanomachining process, the exact construction of nanostructure arrays and the inspection of devices with complex features. Results: The paper encompassed forty patents. Fourteen patents exhibited the manipulation at the micro scale (MEMS manipulations), others outlined systems with sub-micron resolution and workspace range in mesoscale. Standard scale manipulation were described in 13 patents assuming only systems comprising positioning stages, arms and end-effectors where positioners are a few centimeters in size with workspace higher than one cm3. Finally, ten patents included in this review described the importance of end-effectors being extremely important in nanomanipulation as they do support the function defining the manipulation e.g. grippers, sprayers, Nano-tweezers. Conclusion: The findings of this patents review confirm the relevance of the nanomanipulation of objects in 3D system coupled with real time imaging having higher resolution in comparison with the standard manipulators including AFM, TEM, STM, SEM or NSOM. In terms of tooling, AFM cantilever tips, etched tungsten tips or tips with electron beam deposition can be used to manufacture or develop nanodevices e.g. nanowires in in-situ SEM. In handling and manipulating in ambient conditions, commercial microfabricated grippers although available, are less used compared to CNT nanotweezers. Nanomanipulation is currently enabled for nanoscale samples by on-chip operations using promising MEMS and NEMS devices to relatively large samples by the meso and standard scale nanomanipulators. Manipulation is comprehensive and requires multiple functions enabled by various types of end-effectors and probes actuated with high precision. Piezo actuators are at the moment of great performance. Nano and sub-nano samples require proper environment e.g, with electron microscopy to monitor and manipulate including testing, inspecting and fabricating and assembling.
Salem Bashmal; Hassen Ouakad. Nanoscale Manipulators: Review of Conceptual Designs Through Recent Patents. Recent Patents on Nanotechnology 2016, 10, 44 -58.
AMA StyleSalem Bashmal, Hassen Ouakad. Nanoscale Manipulators: Review of Conceptual Designs Through Recent Patents. Recent Patents on Nanotechnology. 2016; 10 (1):44-58.
Chicago/Turabian StyleSalem Bashmal; Hassen Ouakad. 2016. "Nanoscale Manipulators: Review of Conceptual Designs Through Recent Patents." Recent Patents on Nanotechnology 10, no. 1: 44-58.
An electro-mechanical analysis of a microcantilever beam considering the effect of size dependence and flexible supports is presented. Both static and dynamic analyses are performed to show the coupled effect of flexible support and electrical voltage on the static and dynamic performance of the microcantilever beam. The wavelet-based finite element method (FEM) is used to derive the elastodynamic model of the microcantilever beam. The energy expressions are derived using couple stress theory, while additional energy terms are introduced to represent the flexible boundaries and fringing fields. Numerical simulations and comparisons with experimental data show the validity of the developed wavelet-based finite element model and its potential in tackling practical problems in the design and evaluation of micro-devices.
Salem Bashmal; Wasiu Adeyemi Oke; Yehia Khulief. Vibration analysis of an elastically restrained microcantilever beam under electrostatic loading using wavelet‐based finite element method. Micro & Nano Letters 2015, 10, 147 -152.
AMA StyleSalem Bashmal, Wasiu Adeyemi Oke, Yehia Khulief. Vibration analysis of an elastically restrained microcantilever beam under electrostatic loading using wavelet‐based finite element method. Micro & Nano Letters. 2015; 10 (3):147-152.
Chicago/Turabian StyleSalem Bashmal; Wasiu Adeyemi Oke; Yehia Khulief. 2015. "Vibration analysis of an elastically restrained microcantilever beam under electrostatic loading using wavelet‐based finite element method." Micro & Nano Letters 10, no. 3: 147-152.
The prediction of flow rates at which the vibration-induced instability takes place in tubular heat exchangers due to cross flow is of major importance to the performance and service life of such equipment. In this paper, the semi-analytical model is developed and utilized to study the triangular tube patterns. The developed mathematical model is tuned with the experimentally measured fluid-elastic force coefficients. An experimental setup with water channel and instrumented test section is constructed. In this investigation, two test sections are constructed for both the normal triangular and the rotated triangular tube arrays. The developed scheme is utilized for predicting the critical flow velocities at the inception of flow-induced instability in the two triangular tube arrays. The results are compared to those obtained for two other bundle configurations, namely the square and rotated square arrays. The results of the two tube patterns are viewed in light of TEMA predictions. The comparisons demonstrated that TEMA predictions provided more conservative guidelines for all the configurations considered. Field application of the obtained results was successful in extending the service life of tube and shell heat exchangers beyond that predicted by TEMA.
Y. A. Khulief; S. A. Bashmal; S. A. Said; D. A. Al-Otaibi; K. M. Mansour. Prediction of Vibration-Induced Instability Due to Cross Flow in Heat Exchangers with Triangular Tube Arrays. Arabian Journal for Science and Engineering 2014, 39, 8209 -8219.
AMA StyleY. A. Khulief, S. A. Bashmal, S. A. Said, D. A. Al-Otaibi, K. M. Mansour. Prediction of Vibration-Induced Instability Due to Cross Flow in Heat Exchangers with Triangular Tube Arrays. Arabian Journal for Science and Engineering. 2014; 39 (11):8209-8219.
Chicago/Turabian StyleY. A. Khulief; S. A. Bashmal; S. A. Said; D. A. Al-Otaibi; K. M. Mansour. 2014. "Prediction of Vibration-Induced Instability Due to Cross Flow in Heat Exchangers with Triangular Tube Arrays." Arabian Journal for Science and Engineering 39, no. 11: 8209-8219.
The prediction of flow rates at which the vibration-induced instability takes place in tubular heat exchangers due to cross-flow is of major importance to the performance and service life of such equipment. In this paper, the semi-analytical model developed in [1] for square tube arrays was extended and utilized to study the triangular tube patterns. A laboratory test rig with instrumented test section is used to measure the fluidelastic coefficients to be used for tuning the mathematical model. The test section can be made of any bundle pattern. In this study, two test sections were constructed for both the normal triangular and the rotated triangular tube arrays. The developed scheme is utilized in predicting the onset of flow-induced instability in the two triangular tube arrays. The results are compared to those obtained for two other bundle configurations; namely the square and rotated square arrays reported in [1]. The results of the four different tube patterns are viewed in the light of TEMA predictions. The comparison demonstrated that TEMA guidelines are more conservative in all configurations considered.
Yehia A. Khulief; Salem Bashmal; Sayed A. Said; Dhawi A. Al-Otaibi; Khalid M. Mansour. Prediction of the Damaging Flow-Induced Vibrations in Tubular Heat Exchangers With Triangular Arrays. Volume 1A, Symposia: Advances in Fluids Engineering Education; Turbomachinery Flow Predictions and Optimization; Applications in CFD; Bio-Inspired Fluid Mechanics; Droplet-Surface Interactions; CFD Verification and Validation; Development and Applications of Immersed Boundary Methods; DNS, LES, and Hybrid RANS/LES Methods 2014, 1 .
AMA StyleYehia A. Khulief, Salem Bashmal, Sayed A. Said, Dhawi A. Al-Otaibi, Khalid M. Mansour. Prediction of the Damaging Flow-Induced Vibrations in Tubular Heat Exchangers With Triangular Arrays. Volume 1A, Symposia: Advances in Fluids Engineering Education; Turbomachinery Flow Predictions and Optimization; Applications in CFD; Bio-Inspired Fluid Mechanics; Droplet-Surface Interactions; CFD Verification and Validation; Development and Applications of Immersed Boundary Methods; DNS, LES, and Hybrid RANS/LES Methods. 2014; ():1.
Chicago/Turabian StyleYehia A. Khulief; Salem Bashmal; Sayed A. Said; Dhawi A. Al-Otaibi; Khalid M. Mansour. 2014. "Prediction of the Damaging Flow-Induced Vibrations in Tubular Heat Exchangers With Triangular Arrays." Volume 1A, Symposia: Advances in Fluids Engineering Education; Turbomachinery Flow Predictions and Optimization; Applications in CFD; Bio-Inspired Fluid Mechanics; Droplet-Surface Interactions; CFD Verification and Validation; Development and Applications of Immersed Boundary Methods; DNS, LES, and Hybrid RANS/LES Methods , no. : 1.
This study investigates the radial aerodynamic forces that may develop inside the centrifugal compressor and the turbine volutes due to pressure variation of the circulating gas. The forces are numerically predicted for magnitudes, directions, and locations. The radial aerodynamic forces are numerically simulated as static forces in the turbocharger finite element model with floating ring bearings and solved for nonlinear time-transient response. The numerical predictions of the radial aerodynamic forces are computed with correlation to earlier experimental results of the same turbocharger. The outcomes of the investigation demonstrate a significant influence of the radial aerodynamic loads on the turbocharger dynamic stability and the bearing reaction forces. The numerical predictions are also compared with experimental results for validation.
A AlSaeed; G Kirk; S Bashmal. Effects of radial aerodynamic forces on rotor-bearing dynamics of high-speed turbochargers. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 2014, 228, 2503 -2519.
AMA StyleA AlSaeed, G Kirk, S Bashmal. Effects of radial aerodynamic forces on rotor-bearing dynamics of high-speed turbochargers. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science. 2014; 228 (14):2503-2519.
Chicago/Turabian StyleA AlSaeed; G Kirk; S Bashmal. 2014. "Effects of radial aerodynamic forces on rotor-bearing dynamics of high-speed turbochargers." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 228, no. 14: 2503-2519.
The aim of this study is to analytically design flexible damped bearing-supports in order to improve the dynamic characteristics of the rotor-bearing system. The finite-element model of the turbocharger rotor with linearized bearing dynamic coefficients is used to solve for the logarithmic decrements and hence the stability map. The design process attempts to find the optimum dynamic characteristics of the flexible damped bearing-support that would give best dynamic stability of the rotor-bearing system. The method is successful in greatly improving the dynamic stability of the turbocharger and may also lead to a total linear stability throughout the entire speed range when used besides the enhanced-performance hydrodynamic bearings.
A. AlSaeed; G. Kirk; S. Bashmal. Effect of Flexible Damped Bearing-Supports on the Dynamic Stability of High-Speed Turbochargers. Volume 1: Advances in Aerodynamics 2013, 1 .
AMA StyleA. AlSaeed, G. Kirk, S. Bashmal. Effect of Flexible Damped Bearing-Supports on the Dynamic Stability of High-Speed Turbochargers. Volume 1: Advances in Aerodynamics. 2013; ():1.
Chicago/Turabian StyleA. AlSaeed; G. Kirk; S. Bashmal. 2013. "Effect of Flexible Damped Bearing-Supports on the Dynamic Stability of High-Speed Turbochargers." Volume 1: Advances in Aerodynamics , no. : 1.
This study presents an electro-mechanical analysis of a microcantilever beam considering the effect of size dependence and flexible supports. The energy expressions are derived using couple stress theory, while additional energy terms were added to represent the flexible boundaries and fringing fields. Both static and dynamic analyses are performed to show the coupled effect of flexible support, electrical voltage and mechanical loading on the static and dynamic performance of the microcantilever beam.
S. Bashmal. Static and Dynamic Analysis of Microcantilever Beam Under Electrical Loading Using Couple Stress Theory. Volume 1: Advances in Aerodynamics 2013, 1 .
AMA StyleS. Bashmal. Static and Dynamic Analysis of Microcantilever Beam Under Electrical Loading Using Couple Stress Theory. Volume 1: Advances in Aerodynamics. 2013; ():1.
Chicago/Turabian StyleS. Bashmal. 2013. "Static and Dynamic Analysis of Microcantilever Beam Under Electrical Loading Using Couple Stress Theory." Volume 1: Advances in Aerodynamics , no. : 1.
Analytical and experimental investigations are carried out to study the combined effect of rotation and support non-uniformity on the modal characteristics of circular thick disks. A three-dimensional model is implemented to study the coupled in-plane and out-of-plane modes of a thick disk and present the variations of the travelling waves with respect to rotating and fixed coordinates. The initial stiffening due to rotation is introduced by developing a non-linear model that permits the coupling between static and dynamic problems. The present formulation is generalized to account for the stiffening effects for disks subject to non-uniform boundary conditions, where the initial displacement cannot be considered as axisymmetric. The general non-linear problem of a rotating annular disk subject to non-uniform boundary conditions is, then, investigated. The laboratory experiments on stationary and rotating circular disks under selected boundary conditions are carried out to demonstrate the validity of the analytical methods in terms of vibration and acoustic emission behaviour. The experimental results examine the combined effect of rotation and point support on the disk. The experimental study confirms the split in natural frequencies of the disk that was observed in the analytical results due to both rotation and support non-uniformity.
S. Bashmal; R. Bhat; S. Rakheja. Experimental Investigation on the Modal Characteristics of Rolling Thick Disk. Volume 1: Advances in Aerospace Technology 2012, 151 -161.
AMA StyleS. Bashmal, R. Bhat, S. Rakheja. Experimental Investigation on the Modal Characteristics of Rolling Thick Disk. Volume 1: Advances in Aerospace Technology. 2012; ():151-161.
Chicago/Turabian StyleS. Bashmal; R. Bhat; S. Rakheja. 2012. "Experimental Investigation on the Modal Characteristics of Rolling Thick Disk." Volume 1: Advances in Aerospace Technology , no. : 151-161.
In-plane free vibrations of an elastic and isotropic annular disk with elastic constraints at the inner and outer boundaries, which are applied either along the entire periphery of the disk or at a point are investigated. The boundary characteristic orthogonal polynomials are employed in the Rayleigh-Ritz method to obtain the frequency parameters and the associated mode shapes. Boundary characteristic orthogonal polynomials are generated for the free boundary conditions of the disk while artificial springs are used to account for different boundary conditions. The frequency parameters for different boundary conditions of the outer edge are evaluated and compared with those available in the published studies and computed from a finite element model. The computed mode shapes are presented for a disk clamped at the inner edge and point supported at the outer edge to illustrate the free in-plane vibration behavior of the disk. Results show that addition of point clamped support causes some of the higher modes to split into two different frequencies with different mode shapes.
Salem Bashmal; R. Bhat; S. Rakheja. In-Plane free Vibration Analysis of an Annular Disk with Point Elastic Support. Shock and Vibration 2011, 18, 627 -640.
AMA StyleSalem Bashmal, R. Bhat, S. Rakheja. In-Plane free Vibration Analysis of an Annular Disk with Point Elastic Support. Shock and Vibration. 2011; 18 (4):627-640.
Chicago/Turabian StyleSalem Bashmal; R. Bhat; S. Rakheja. 2011. "In-Plane free Vibration Analysis of an Annular Disk with Point Elastic Support." Shock and Vibration 18, no. 4: 627-640.