Shahrood University of TechnologyJournal of Solid and Fluid Mechanics2251-947514320240722Comparison of cooling performance in a microchannel with discrete heat sources under pressure gradient and electroosmotic drivenComparison of cooling performance in a microchannel with discrete heat sources under pressure gradient and electroosmotic driven110325510.22044/jsfm.2024.13378.3764FAAminHadizadeKilometer 5 Of Rasht To Tehran HighwaySaeedJamshidiKilometer 5 Of Rasht To Tehran HighwayAminHaghighi PoshtiriKilometer 5 Of Rasht To Tehran HighwayJournal Article20230715Electronic devices and advanced equipments have various sections that generated heat is a common feature among them, and sometimes it becomes so intense that it requires the design of a new structure to help cool them. However, the challenge becomes more complex when the device is in micro or nano size, where ordinary pumps with electrical components cannot function. This study addresses this issue using electroosmotic micro-pumps and examines the effect of microchannel angle and gravity on heat transfer rate. The microchannel angle ranges from 0 to 75 degrees, and the Grashof number varies between 0 and 100. For better understanding, the results obtained from a pressure-driven flow are compared with those from a purely electroosmotic flow while maintaining a constant flow rate. Thermal performance index is employed to measure the efficiency of flow patterns in both cases. The calculated variations range from approximately 11% to over 44%, indicating that two factors, increasing the microchannel angle relative to the horizontal plane and decreasing the Grashof number, exhibit similar behavior and enhance the heat transfer efficiency.Electronic devices and advanced equipments have various sections that generated heat is a common feature among them, and sometimes it becomes so intense that it requires the design of a new structure to help cool them. However, the challenge becomes more complex when the device is in micro or nano size, where ordinary pumps with electrical components cannot function. This study addresses this issue using electroosmotic micro-pumps and examines the effect of microchannel angle and gravity on heat transfer rate. The microchannel angle ranges from 0 to 75 degrees, and the Grashof number varies between 0 and 100. For better understanding, the results obtained from a pressure-driven flow are compared with those from a purely electroosmotic flow while maintaining a constant flow rate. Thermal performance index is employed to measure the efficiency of flow patterns in both cases. The calculated variations range from approximately 11% to over 44%, indicating that two factors, increasing the microchannel angle relative to the horizontal plane and decreasing the Grashof number, exhibit similar behavior and enhance the heat transfer efficiency.https://jsfm.shahroodut.ac.ir/article_3255_b0e5158efd2c7821355be188778090ff.pdfShahrood University of TechnologyJournal of Solid and Fluid Mechanics2251-947514320240722Thermodynamic analysis of an HDH water desalination system with a solar-driven absorption refrigeration cycleThermodynamic analysis of an HDH water desalination system with a solar-driven absorption refrigeration cycle1125325610.22044/jsfm.2024.13562.3792FAMortezaHadadibabol noshirvani university of technologyRozbehShafaghatProf., Mech. Eng., Babol Noshirvani University of Technology, Babol, IranAmirhosseinAghajani AfghanPh.D. Student, Mechanical Engineering, Energy conversion, Iran University of Science and TechnologyJournal Article20230914This research investigates an HDH humidifier-dehumidifier cycle that incorporates a direct contact dehumidifier and a single-effect solar absorption refrigeration system (ARS). Due to its utilization of biomass, solar energy, and geothermal energy for chilling purposes, absorption refrigeration systems are being examined for their environmentally friendly design. The system's performance was evaluated across several operational scenarios by employing a mathematical model. In order to incorporate the impact of humidification and dehumidification units into the theoretical modeling, the correlation was employed to examine the heat and mass transport in the system under consideration. The system's performance was evaluated using performance parameters such as recovery ratio (RR), coefficient of performance (COP), and output gain ratio (GOR). An investigation was conducted on the state of the hybrid HDH system in conjunction with an absorption refrigeration system, considering various cooling situations. Studies have demonstrated that modifying the ratio of saline water to fresh water or saline water to dry air in an HDH system allows for the integration of an absorption refrigeration system of the water-ammonia type, without requiring extra cooling load. This adjustment successfully achieved a favorable recovery ratio. In order to prevent the requirement for extra cooling, the system can be initiated within the range of values that are less than 2.5 and greater than 4.2.This research investigates an HDH humidifier-dehumidifier cycle that incorporates a direct contact dehumidifier and a single-effect solar absorption refrigeration system (ARS). Due to its utilization of biomass, solar energy, and geothermal energy for chilling purposes, absorption refrigeration systems are being examined for their environmentally friendly design. The system's performance was evaluated across several operational scenarios by employing a mathematical model. In order to incorporate the impact of humidification and dehumidification units into the theoretical modeling, the correlation was employed to examine the heat and mass transport in the system under consideration. The system's performance was evaluated using performance parameters such as recovery ratio (RR), coefficient of performance (COP), and output gain ratio (GOR). An investigation was conducted on the state of the hybrid HDH system in conjunction with an absorption refrigeration system, considering various cooling situations. Studies have demonstrated that modifying the ratio of saline water to fresh water or saline water to dry air in an HDH system allows for the integration of an absorption refrigeration system of the water-ammonia type, without requiring extra cooling load. This adjustment successfully achieved a favorable recovery ratio. In order to prevent the requirement for extra cooling, the system can be initiated within the range of values that are less than 2.5 and greater than 4.2.https://jsfm.shahroodut.ac.ir/article_3256_e11cdd35f6d39c96acce9e434570dd91.pdfShahrood University of TechnologyJournal of Solid and Fluid Mechanics2251-947514320240722Experimental study of combination of air and thermo-electric cooling methods to increase the operating time and reduce the temperature of the lithium ion batteryExperimental study of combination of air and thermo-electric cooling methods to increase the operating time and reduce the temperature of the lithium ion battery2742325910.22044/jsfm.2024.14072.3831FAAhmadNajafiSemnan UniversityAmir MohammadJadidiعضو هیات علمیSamanRashidiDepartment of Energy, Faculty of New Sciences and Technologies, Semnan University, Semnan, IranJournal Article20240120Rechargeable batteries have an inseparable role in today's life, maintaining and increasing their lifespan has been one of the challenges of mankind. In this article, by examining and combining air cooling and thermoelectric modules,. The effect of temperature and different discharge rates is investigated in this article. The battery pack was made of aluminum block with dimensions of 30x10x6 cm. 48 lithium ion battery cells are placed on it. The arrangement of these cells was in the form of 4 rows in 12 columns. Considering the capacity of 2200 mAh and the voltage of 3.7 volts, the maximum power of the set is 390 Wh. The fan is placed at a distance of 60 cm from the set. The speed of the wind facing the pack was equal to 1.2 m/s. In the mode of simultaneous use of the fan and the thermoelectric module, the operating time has increased by 17.1% compared to the mode without the use of the fan and the thermoelectric module, and has reached 1900 seconds to 2300 seconds. The surface temperature of the set has decreased by 2 degrees in the mode of simultaneous use of the fan and the module. The amount of heat transfer by fan cooling system and thermoelectric module has improved by 15.2% compared to the case without fan and module. The Nusselt number has grown by 14.2% in the combined state compared to the basic state. By comparing the results the suitability of this cooling method has been confirmed.Rechargeable batteries have an inseparable role in today's life, maintaining and increasing their lifespan has been one of the challenges of mankind. In this article, by examining and combining air cooling and thermoelectric modules,. The effect of temperature and different discharge rates is investigated in this article. The battery pack was made of aluminum block with dimensions of 30x10x6 cm. 48 lithium ion battery cells are placed on it. The arrangement of these cells was in the form of 4 rows in 12 columns. Considering the capacity of 2200 mAh and the voltage of 3.7 volts, the maximum power of the set is 390 Wh. The fan is placed at a distance of 60 cm from the set. The speed of the wind facing the pack was equal to 1.2 m/s. In the mode of simultaneous use of the fan and the thermoelectric module, the operating time has increased by 17.1% compared to the mode without the use of the fan and the thermoelectric module, and has reached 1900 seconds to 2300 seconds. The surface temperature of the set has decreased by 2 degrees in the mode of simultaneous use of the fan and the module. The amount of heat transfer by fan cooling system and thermoelectric module has improved by 15.2% compared to the case without fan and module. The Nusselt number has grown by 14.2% in the combined state compared to the basic state. By comparing the results the suitability of this cooling method has been confirmed.https://jsfm.shahroodut.ac.ir/article_3259_421d6a18565de0837007b396429af469.pdfShahrood University of TechnologyJournal of Solid and Fluid Mechanics2251-947514320240722Nonlinear dynamic response of truncated conical shells reinforced with carbon nanotubes with functional graded ceramic-metal matrix under harmonic excitationNonlinear dynamic response of truncated conical shells reinforced with carbon nanotubes with functional graded ceramic-metal matrix under harmonic excitation4356326010.22044/jsfm.2024.14238.3842FAMahmoudShadmaniDepartment of Mechanical Engineering, Islamic Azad University Shiraz branch, Shiraz,AhmadAfsariDepartment of Mechanical Engineering, Islamic Azad University Shiraz branch, Shiraz, IranRezaJahediDepartment of Mechanical Engineering, Islamic Azad University Shiraz branch, Shiraz, IranMohammad JavadKazemzadeh-ParsiDepartment of Mechanical Engineering, Islamic Azad University Shiraz branch, Shiraz, IranJournal Article20240229This paper analyzes the nonlinear dynamic response of truncated conical shells reinforced with carbon nanotubes with functional graded ceramic-metal matrix subjected to harmonic excitation. Carbon nanotubes are distributed with three different patterns along the length and thickness of the conical shell. The matrix material of the shell is considered to be a combination of metal and ceramic, whose properties change as a power function along the thickness of the shell. In order to analyze the dynamic of this system, firstly, the nonlinear dynamic equations of the conical shell are derived based on the first order shear deformation theory and von Karman's strain-displacement relations. Then, with the help of Galerkin discretization method, partial differential equations of the system are converted into time-dependent ordinary differential equations. Adams-Bashforth numerical method is used to solve the system of nonlinear differential equations. Finally, a parametric study is presented to investigate the effects of some parameters of the system, such as the power index, volume fraction and distribution pattern of carbon nanotubes, the geometric characteristics of the shell, and amplitude of the excitation force on the nonlinear dynamic response of the conical shell. In order to validate, the results of this article are compared and presented with the results of previous valid references.This paper analyzes the nonlinear dynamic response of truncated conical shells reinforced with carbon nanotubes with functional graded ceramic-metal matrix subjected to harmonic excitation. Carbon nanotubes are distributed with three different patterns along the length and thickness of the conical shell. The matrix material of the shell is considered to be a combination of metal and ceramic, whose properties change as a power function along the thickness of the shell. In order to analyze the dynamic of this system, firstly, the nonlinear dynamic equations of the conical shell are derived based on the first order shear deformation theory and von Karman's strain-displacement relations. Then, with the help of Galerkin discretization method, partial differential equations of the system are converted into time-dependent ordinary differential equations. Adams-Bashforth numerical method is used to solve the system of nonlinear differential equations. Finally, a parametric study is presented to investigate the effects of some parameters of the system, such as the power index, volume fraction and distribution pattern of carbon nanotubes, the geometric characteristics of the shell, and amplitude of the excitation force on the nonlinear dynamic response of the conical shell. In order to validate, the results of this article are compared and presented with the results of previous valid references.https://jsfm.shahroodut.ac.ir/article_3260_4b686ae8d0f275fccb071dd4d4f0154c.pdfShahrood University of TechnologyJournal of Solid and Fluid Mechanics2251-947514320240722Simulation and Optimization of a Hybrid Renewable System for Providing Electrical and Thermal Energy at Faculty of Engineering, Golestan UniversitySimulation and Optimization of a Hybrid Renewable System for Providing Electrical and Thermal Energy at Faculty of Engineering, Golestan University5776326110.22044/jsfm.2024.14276.3845FAMohammadShakkiGolestan universitySeiyed Mohammad JavadHosseini KahsariDepartment of Mechanical Engineering, Faculty of Engineering, Golestan University, Gorgan, IranMehdiEisapourUniversity of CalgaryJournal Article20240305The energy demand is growing daily due to the growing population, rising electricity consumption, and widespread usage of advanced equipment. The environmental damage caused by fossil fuels and their economic and political implications in countries worldwide has prompted a quest for alternative energy sources. One of the key advantages of renewable energy sources is their ability to combine with other energy sources to create hybrid renewable energy systems. Hybrid renewable systems are devices that utilize more than one energy generation source to fulfill the required electrical and thermal loads. In this study, a hybrid renewable energy system has been designed for the Faculty of Engineering of Golestan University located in Gorgan City, utilizing Homer software. This system, which includes solar panels, wind turbines, diesel generators and grid power integration, fulfills the energy needs of the facility. Additionally, heating needs are supplied using a boiler and heat controller. The results indicate that the optimized system has a total current cost of $214,266, with a cost of energy production per kilowatt-hour amounting to 0.0159 $ and the renewable resource contribution is 71.7%. Moreover, the sensitivity analysis reveals that when the inflation rate surges to 20%, the current cost of the whole project ascends to 16 %.The energy demand is growing daily due to the growing population, rising electricity consumption, and widespread usage of advanced equipment. The environmental damage caused by fossil fuels and their economic and political implications in countries worldwide has prompted a quest for alternative energy sources. One of the key advantages of renewable energy sources is their ability to combine with other energy sources to create hybrid renewable energy systems. Hybrid renewable systems are devices that utilize more than one energy generation source to fulfill the required electrical and thermal loads. In this study, a hybrid renewable energy system has been designed for the Faculty of Engineering of Golestan University located in Gorgan City, utilizing Homer software. This system, which includes solar panels, wind turbines, diesel generators and grid power integration, fulfills the energy needs of the facility. Additionally, heating needs are supplied using a boiler and heat controller. The results indicate that the optimized system has a total current cost of $214,266, with a cost of energy production per kilowatt-hour amounting to 0.0159 $ and the renewable resource contribution is 71.7%. Moreover, the sensitivity analysis reveals that when the inflation rate surges to 20%, the current cost of the whole project ascends to 16 %.https://jsfm.shahroodut.ac.ir/article_3261_0750c598115abd364f38ae384bedbf6f.pdfShahrood University of TechnologyJournal of Solid and Fluid Mechanics2251-947514320240722Dynamics of Confined Spherical Gas Bubbles in an Elastic Vessel Filled with a Thixotropic FluidDynamics of Confined Spherical Gas Bubbles in an Elastic Vessel Filled with a Thixotropic Fluid7793326210.22044/jsfm.2024.13864.3813FAMohammadPourjafar ChelikdaniDepartment of Mechanical Engineering, Caspian Faculty of Engineering, University of Tehran, Rezvanshahr, IranHaniehAsadi HamzehkandiDepartment of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, IranKayvanSadeghyDepartment of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, IranJournal Article20231121In this paper numerical investigation of the dynamics of a tiny spherical gas bubble surrounded by an incompressible fluid confined in a vessel has been addressed when the bubble is subjected to accousting forcing of vessel wall. The liquid surrounding the bubble has been assumed to be thixotropic, which has been modelled using the Moore model. The vessel has also been assumed to be deformable obeying the linear-elastic model. After deriving the integro-differential equations governing the bubble dynamics, the governing equations have been solved using ODE23s solver in the MATLAB software numerically. Based on the obtained numerical results, an increase in the parameters such as fluid’s viscosity ratio, vessel wall’s elasticity, vapor pressure, gas pressure trapped in the bubble, and also geometric factor had totally considerable effect to reduce the gaseous bubble’s amplitude of oscillations. However, an increase in the parameters such as fluid’s thixotropy number, break down number, bubble/fluid interfacial surface tension, and also flow Reynolds number has leaded in growth of the bubble oscillations. Moreover, strong fluid’s shear thinning behavior beside small values of interfacial surface tension were known as two important factors to avoid from excessive increase of elastic coating maximum radial stress.In this paper numerical investigation of the dynamics of a tiny spherical gas bubble surrounded by an incompressible fluid confined in a vessel has been addressed when the bubble is subjected to accousting forcing of vessel wall. The liquid surrounding the bubble has been assumed to be thixotropic, which has been modelled using the Moore model. The vessel has also been assumed to be deformable obeying the linear-elastic model. After deriving the integro-differential equations governing the bubble dynamics, the governing equations have been solved using ODE23s solver in the MATLAB software numerically. Based on the obtained numerical results, an increase in the parameters such as fluid’s viscosity ratio, vessel wall’s elasticity, vapor pressure, gas pressure trapped in the bubble, and also geometric factor had totally considerable effect to reduce the gaseous bubble’s amplitude of oscillations. However, an increase in the parameters such as fluid’s thixotropy number, break down number, bubble/fluid interfacial surface tension, and also flow Reynolds number has leaded in growth of the bubble oscillations. Moreover, strong fluid’s shear thinning behavior beside small values of interfacial surface tension were known as two important factors to avoid from excessive increase of elastic coating maximum radial stress.https://jsfm.shahroodut.ac.ir/article_3262_70e0495f0d6115335e6593a74a46301e.pdfShahrood University of TechnologyJournal of Solid and Fluid Mechanics2251-947514320240722Experimental investigation of the mechanical behavior of the core composed of polyurethane foam and scoria mineral pumice for use in explosive energy absorbent sandwich panelsExperimental investigation of the mechanical behavior of the core composed of polyurethane foam and scoria mineral pumice for use in explosive energy absorbent sandwich panels95106326510.22044/jsfm.2024.13942.3817FAMahmoudKaffash MirzarahimiMechanical Engineering, Faculty of Engineering, Imam Hossein University, TehranHosseinKhodarahmiProfessor of Mechanics and Aerospace Department of Imam Hossein UniversityMojtabaGhamarizadehImam Hossein Univ. for Training Officers & GuardsMojtabaZia ShamamiFaculty of Mechanical Engineering, Imam Hussein University, Tehran, IranRouhollahHosseiniDepartment of Mechanical Engineering
Imam Hossein UniversityJournal Article20231209In this article, a new type of explosion energy absorbing sandwich panel has been introduced and studied experimentally. Its core is a combination of polyurethane foam and scoria mineral pumice with two different types of granulation. To study the behavior of this panels, 3 different types of tests have been performed. In the first series of tests, the matrix used in the core composition is selected. The selection criterion is the strength performance and energy absorption by the core of the sandwich panel. In the core matrix selection test, the performance of the core composed of polyurethane foam and mineral pumice is investigated under the load caused by free explosion. In the second series of experimental tests, material properties including stress-strain diagram and energy absorption efficiency of core, by pressure test and its results are presented. In the third series of tests, the mechanical behavior of the sheet and the maximum deflection of the back face have been evaluated. The composition of the new core has been studied, investigated and introduced, and it was approved according to the quality of energy absorption, lightness, strength, cost of preparation and easy production of the core with optimal energy absorption efficiency.In this article, a new type of explosion energy absorbing sandwich panel has been introduced and studied experimentally. Its core is a combination of polyurethane foam and scoria mineral pumice with two different types of granulation. To study the behavior of this panels, 3 different types of tests have been performed. In the first series of tests, the matrix used in the core composition is selected. The selection criterion is the strength performance and energy absorption by the core of the sandwich panel. In the core matrix selection test, the performance of the core composed of polyurethane foam and mineral pumice is investigated under the load caused by free explosion. In the second series of experimental tests, material properties including stress-strain diagram and energy absorption efficiency of core, by pressure test and its results are presented. In the third series of tests, the mechanical behavior of the sheet and the maximum deflection of the back face have been evaluated. The composition of the new core has been studied, investigated and introduced, and it was approved according to the quality of energy absorption, lightness, strength, cost of preparation and easy production of the core with optimal energy absorption efficiency.https://jsfm.shahroodut.ac.ir/article_3265_606fea14e0dfb64e633072e830a37cc9.pdfShahrood University of TechnologyJournal of Solid and Fluid Mechanics2251-947514320240722Modeling the hydraulic-thermal performance of a sinusoidal semi-porous channel with nanofluid flow and applying a magnetic fieldModeling the hydraulic-thermal performance of a sinusoidal semi-porous channel with nanofluid flow and applying a magnetic field107123326610.22044/jsfm.2024.14036.3828FANejatSheikhpourPhD graduate, Department of Mechanical Engineering, Central Tehran Branch, Islamic Azad University, Tehran, IranArashMirabdolah LavasaniAssociate Professor, Department of Mechanical Engineering, Central Tehran Branch, Islamic Azad University, Tehran, IranGholamrezaSalehiAssociate Professor, Department of Mechanical Engineering, Central Tehran Branch, Islamic Azad University, Tehran, Iran0000-0002-7866-358XJournal Article20240108In this study, the hydraulic-thermal performance of a semi-porous wave channel with nanofluid flow and applied magnetic field has been evaluated. The magnetic field is perpendicular to the channel. In this design, single-phase, incompressible and permanent nanofluid flow is considered. The ranges of Hartmann number and Darcy number are 0 ≤ Ha ≤ 10 and 10-5 ≤ Da ≤ 10-2, respectively. Magnesium oxide nanoparticles have been investigated in four different volume fractions (0, 2, 4 and 5%). The governing equations are solved by the finite volume method. Based on the obtained results, increasing the volume fraction of nanoparticles and channel wave improves heat transfer. At constant Reynolds number, increasing the number of wave channels from 4 to 6 resulted in a 7.8% decrease in thermal hydraulics. The increase in permeability in the porous medium has increased the Nusselt number and reduced friction. The best thermal hydraulic performance is 10.08 at Darcy number 0.01 and the lowest is 0.52 at Darcy number 0.0001. Also, the presence of magnetic field has a positive effect on thermal performance. The results of this study can be useful in the design of heat exchangers.In this study, the hydraulic-thermal performance of a semi-porous wave channel with nanofluid flow and applied magnetic field has been evaluated. The magnetic field is perpendicular to the channel. In this design, single-phase, incompressible and permanent nanofluid flow is considered. The ranges of Hartmann number and Darcy number are 0 ≤ Ha ≤ 10 and 10-5 ≤ Da ≤ 10-2, respectively. Magnesium oxide nanoparticles have been investigated in four different volume fractions (0, 2, 4 and 5%). The governing equations are solved by the finite volume method. Based on the obtained results, increasing the volume fraction of nanoparticles and channel wave improves heat transfer. At constant Reynolds number, increasing the number of wave channels from 4 to 6 resulted in a 7.8% decrease in thermal hydraulics. The increase in permeability in the porous medium has increased the Nusselt number and reduced friction. The best thermal hydraulic performance is 10.08 at Darcy number 0.01 and the lowest is 0.52 at Darcy number 0.0001. Also, the presence of magnetic field has a positive effect on thermal performance. The results of this study can be useful in the design of heat exchangers.https://jsfm.shahroodut.ac.ir/article_3266_6dd6c1d82017369236f87e2989362a83.pdfShahrood University of TechnologyJournal of Solid and Fluid Mechanics2251-947514320240722Comparison of nonclassical controllers on piezoelectric nanoresonator: nonlinear frequency response and stability analysisComparison of nonclassical controllers on piezoelectric nanoresonator: nonlinear frequency response and stability analysis125139326710.22044/jsfm.2024.14369.3851FASayyid H.Hashemi KachapiAssistant Professor, Department of Mechanical Engineering, University of Mazandaran, Babolsar, Islamic Republic of ‎IranS. Gh.Hashemi KachapiPh.D. Student, Department of Physics, University of Kashan, Kashan, Islamic Republic of IranJournal Article20240401In current study, nonlinear vibrations and stability analysis of piezoelectric nanoresonator (PENR) considering with the effects of non-classical controllers such as strain gradient (SGT), nonlocal (NLT) and Gurtin–Murdoch surface/interface (GMSIT) theories are presented in comparison with the classical theory (CT). PENR subjected to nonlinear electrostatic excitation with direct (DC) and alternative (AC) voltages and also visco-pasternak medium. For this work, Hamilton’s principle and Galerkin technique are used to obtain the governing equations and boundary conditions and also to solve the equation of motion. Complex averaging method combined with arc-length continuation is used to investigate nonlinear frequency response and stability analysis of PENR. The results show that ignoring small-scale and surface/interface effects give inaccurate predictions of vibrational response of the PENR. It is indicated that in different boundary condition, material length scale and nonlocal scale parameters respectively lead to decreasing and increasing of PENR stiffness and also the amplitude of oscillation and the range of instability of non-classic theories of NLT and SGT are greater than that of the classical one. Also changes of surface/interface parameters lead to decreasing or increasing of the resonant frequency, resonance amplitude, nonlinear behavior and the system's instability of PENR.In current study, nonlinear vibrations and stability analysis of piezoelectric nanoresonator (PENR) considering with the effects of non-classical controllers such as strain gradient (SGT), nonlocal (NLT) and Gurtin–Murdoch surface/interface (GMSIT) theories are presented in comparison with the classical theory (CT). PENR subjected to nonlinear electrostatic excitation with direct (DC) and alternative (AC) voltages and also visco-pasternak medium. For this work, Hamilton’s principle and Galerkin technique are used to obtain the governing equations and boundary conditions and also to solve the equation of motion. Complex averaging method combined with arc-length continuation is used to investigate nonlinear frequency response and stability analysis of PENR. The results show that ignoring small-scale and surface/interface effects give inaccurate predictions of vibrational response of the PENR. It is indicated that in different boundary condition, material length scale and nonlocal scale parameters respectively lead to decreasing and increasing of PENR stiffness and also the amplitude of oscillation and the range of instability of non-classic theories of NLT and SGT are greater than that of the classical one. Also changes of surface/interface parameters lead to decreasing or increasing of the resonant frequency, resonance amplitude, nonlinear behavior and the system's instability of PENR.https://jsfm.shahroodut.ac.ir/article_3267_ea1a572483bf3b8bc70b3bc2c39eceda.pdfShahrood University of TechnologyJournal of Solid and Fluid Mechanics2251-947514320240722On the use of J-integral criterion for fracture assessment of cracked rigid polyurethane foam loaded in mixed mode I/II and I/IIIOn the use of J-integral criterion for fracture assessment of cracked rigid polyurethane foam loaded in mixed mode I/II and I/III141151326810.22044/jsfm.2024.14305.3847FAMohammad MahdiTouiserkaniDepartment of Mechanical engineering, Yazd universityMahdiHeydari MeybodiDepartment of mechanical engineering, Yazd universityJournal Article20240315The present study investigates and evaluates the J-integral criterion for rigid polyurethane foam using a cracked disk specimen subjected to bending with mixed mode I/II and I/III loading conditions. The primary objective of this study is to assess relationships for the J integral based on a new approach involving the strain energy density in a linear elastic material loaded under mixed mode conditions. To do so, the relevant relationships for a V-notch specimen are first derived and then extended to a cracked sample. The secondary aim of this research is to predict the fracture load using the J-integral criterion in mixed mode I/II and I/III loading conditions in rigid polyurethane foams. To validate the criterion, finite element modeling of a cracked disk specimen is carried out and the fracture load of the specimen under mixed mode I/II and I/III conditions is predicted according to the J-integral criterion. The results reveal the high accuracy of the criterion in predicting the fracture load of specimens under mixed mode conditions, with the maximum error percentage of 8%.The present study investigates and evaluates the J-integral criterion for rigid polyurethane foam using a cracked disk specimen subjected to bending with mixed mode I/II and I/III loading conditions. The primary objective of this study is to assess relationships for the J integral based on a new approach involving the strain energy density in a linear elastic material loaded under mixed mode conditions. To do so, the relevant relationships for a V-notch specimen are first derived and then extended to a cracked sample. The secondary aim of this research is to predict the fracture load using the J-integral criterion in mixed mode I/II and I/III loading conditions in rigid polyurethane foams. To validate the criterion, finite element modeling of a cracked disk specimen is carried out and the fracture load of the specimen under mixed mode I/II and I/III conditions is predicted according to the J-integral criterion. The results reveal the high accuracy of the criterion in predicting the fracture load of specimens under mixed mode conditions, with the maximum error percentage of 8%.https://jsfm.shahroodut.ac.ir/article_3268_83595fe2d95a8a337feaccde53a66129.pdf