Junjian Hou, L. Zeng, Y. Zhong, Dengfeng Zhao, Mingyuan Zhao
Accurate and effective calculation of weakly singular integral in the boundary integral equation of the thin-structural problem is the key to the numerical implementation of the boundary element method. In this paper, a subdivision transformation method evaluated for weakly singular integrals is proposed, and the method is implemented as follows: based on the position of the source points, the shape information of the elements and the nearest distance from the source point to the integral element, a subdivision technology is constructed at first. With this subdivision technology, the integral element can be divided into several integral blocks with good shapes. And then, a simpler coordinate transformation method is constructed to remove the weak singularities of the integral blocks obtained by the subdivision technology. Compared with the conventional polar coordinate transformation method, the present transformation method does not need to calculate their integral interval, which is more simple and effective to implement. Finally, the paper gives three numerical examples to verify the accuracy and validity of the present method.
{"title":"A Subdivision Transformation Method for Weakly Singular Boundary Integrals in Thin-structural Problem","authors":"Junjian Hou, L. Zeng, Y. Zhong, Dengfeng Zhao, Mingyuan Zhao","doi":"10.5755/j02.mech.31683","DOIUrl":"https://doi.org/10.5755/j02.mech.31683","url":null,"abstract":"Accurate and effective calculation of weakly singular integral in the boundary integral equation of the thin-structural problem is the key to the numerical implementation of the boundary element method. In this paper, a subdivision transformation method evaluated for weakly singular integrals is proposed, and the method is implemented as follows: based on the position of the source points, the shape information of the elements and the nearest distance from the source point to the integral element, a subdivision technology is constructed at first. With this subdivision technology, the integral element can be divided into several integral blocks with good shapes. And then, a simpler coordinate transformation method is constructed to remove the weak singularities of the integral blocks obtained by the subdivision technology. Compared with the conventional polar coordinate transformation method, the present transformation method does not need to calculate their integral interval, which is more simple and effective to implement. Finally, the paper gives three numerical examples to verify the accuracy and validity of the present method.","PeriodicalId":54741,"journal":{"name":"Mechanika","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2023-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44806287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this present work, simulations were carried out numerically to characterize a porous material. The basic equations, which govern this problem, are those of the Navier-Stokes equations coupled with the Darcy equation. In order to understand the phenomena at stake, a first test was first completed on the independence of the mesh compared to the numerical solution obtained, the second test is devoted to the validation of Darcy (Re <<1). The characterization of the material is based on physical tests; the first is devoted to the porosity of the material, the second to the thickness, and the trireme to the saturation. The results are presented on the one hand contours for the velocity fields and streamlines, and on the other hand, are illustrated with curves to interpret the physical parameters studied in relation to each other.
{"title":"Modeling and characterization of a porous medium by a coupled approach between the Wavier-Stokes and Darcy equations","authors":"Khelifa Hami, A. Talhi","doi":"10.5755/j02.mech.31832","DOIUrl":"https://doi.org/10.5755/j02.mech.31832","url":null,"abstract":"In this present work, simulations were carried out numerically to characterize a porous material. The basic equations, which govern this problem, are those of the Navier-Stokes equations coupled with the Darcy equation. In order to understand the phenomena at stake, a first test was first completed on the independence of the mesh compared to the numerical solution obtained, the second test is devoted to the validation of Darcy (Re <<1). The characterization of the material is based on physical tests; the first is devoted to the porosity of the material, the second to the thickness, and the trireme to the saturation. The results are presented on the one hand contours for the velocity fields and streamlines, and on the other hand, are illustrated with curves to interpret the physical parameters studied in relation to each other.","PeriodicalId":54741,"journal":{"name":"Mechanika","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2023-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46402234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Such robots, when they consist of two separate sequentially connected robots, are of high precision. The first part – robot is not of a high precision adjusted to perform comparatively large displacements, while the second part – robot is meant to perform comparatively small displacements with very high precision if compared with the first part. Motors of all the motions are of vibrational type. First of all, vibrators of vibrational impact type with impacts of rigid bodies are investigated. Earlier it was shown that in some types of nonlinear systems between the hard and soft zones of excitation of vibrations optimal regimes according to the shape of motion exist. Here this fact is generalized for the vibrator with two symmetric impacting pairs of elements. According to the model of the system free vibrations of the system and their parameters are determined as well as forced harmonic vibrations and their specific features are determined. Recommendations for practical applications are provided.
{"title":"Vibration Drives with Two Impacting Pairs for Precise Robots","authors":"K. Ragulskis, L. Ragulskis","doi":"10.5755/j02.mech.32277","DOIUrl":"https://doi.org/10.5755/j02.mech.32277","url":null,"abstract":"Such robots, when they consist of two separate sequentially connected robots, are of high precision. The first part – robot is not of a high precision adjusted to perform comparatively large displacements, while the second part – robot is meant to perform comparatively small displacements with very high precision if compared with the first part. Motors of all the motions are of vibrational type. \u0000First of all, vibrators of vibrational impact type with impacts of rigid bodies are investigated. \u0000Earlier it was shown that in some types of nonlinear systems between the hard and soft zones of excitation of vibrations optimal regimes according to the shape of motion exist. Here this fact is generalized for the vibrator with two symmetric impacting pairs of elements. According to the model of the system free vibrations of the system and their parameters are determined as well as forced harmonic vibrations and their specific features are determined. Recommendations for practical applications are provided.","PeriodicalId":54741,"journal":{"name":"Mechanika","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2023-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41292865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kishorekanna Gunasekaran, Isaac Solomon, P. Griškevičius
Structural steel is ductile in nature, this is the reason it is used in most of the Sectors in the manufacturing industry. Despite its structural strength, it faces compelling and challenging failures due to unstable, fatigue, dynamic and shock loads. This research study evaluates the structural response on one of these loading conditions using the finite element method. The design of a lower suspension arm of an automobile is modelled in Solidworks 2020 and is solved for static elastic conditions in Ansys 2021 R1. A set of pre-induced fractures are then integrated into the computational model in the Stress concentration zones in different parts of the body and solved independently. A total of five micro-cracks are induced with each crack consisting of six contours. For the numerical simulation of lower suspension arm, real-time loading conditions must be attained to resemble real-world loading scenario. Hence, 4 modes of solving were chosen which would depict the real-world failure scenario where the suspension lower arm can attain maximum loads. The maximum load values are estimated in each mode and is integrated into the model with predefined boundary conditions for the computational approach. A detailed numerical comparative conclusion is drawn regarding the SIFs of every mode and the crack that pertains maximum crack propagation rate.
{"title":"Numerical estimation of the influence of pre-induced micro-cracks in the stress concentration zone on the SIFs of a lower suspension arm","authors":"Kishorekanna Gunasekaran, Isaac Solomon, P. Griškevičius","doi":"10.5755/j02.mech.31660","DOIUrl":"https://doi.org/10.5755/j02.mech.31660","url":null,"abstract":"Structural steel is ductile in nature, this is the reason it is used in most of the Sectors in the manufacturing industry. Despite its structural strength, it faces compelling and challenging failures due to unstable, fatigue, dynamic and shock loads. \u0000 This research study evaluates the structural response on one of these loading conditions using the finite element method. The design of a lower suspension arm of an automobile is modelled in Solidworks 2020 and is solved for static elastic conditions in Ansys 2021 R1. A set of pre-induced fractures are then integrated into the computational model in the Stress concentration zones in different parts of the body and solved independently. A total of five micro-cracks are induced with each crack consisting of six contours. For the numerical simulation of lower suspension arm, real-time loading conditions must be attained to resemble real-world loading scenario. Hence, 4 modes of solving were chosen which would depict the real-world failure scenario where the suspension lower arm can attain maximum loads. The maximum load values are estimated in each mode and is integrated into the model with predefined boundary conditions for the computational approach. \u0000 A detailed numerical comparative conclusion is drawn regarding the SIFs of every mode and the crack that pertains maximum crack propagation rate.","PeriodicalId":54741,"journal":{"name":"Mechanika","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2023-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42585539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Donatas Gricius, Rasa Kandrotaitė Janutienė, D. Mazeika, Rolandas Sertvytis, O. Syzonenko, A. Torpakov
The Ti-based metal matrix composite samples are novel, fabricated by using high voltage electric discharge and spark plasma sintering processes. They have potential usage in the aviation industry. A research that allowed measuring an electrical conductivity of Ti-based composites was performed. A collinear four-point probe method was chosen for measurement of electrical conductivity. Needle-like probes were used to contact the tested sample. Other aspects of the measurement setup are discussed and selected according to relevant literature. A simulation was performed using COMSOL software to validate the measurement method. Furthermore, a simulation performed for contact force of the probes was performed. A 3D model of the measurement tool was created and designed. The measurement setup was tested and validated by using a copper sample. electrical resistance of Ti-based composite samples was measured, and electrical conductivity was calculated. Furthermore, samples were measured at different temperatures and resistivity dependence to temperature was presented. Experimental results are compared to similar research results.
{"title":"Development of Determination Methodology of Electrical Conductivity of Titanium-based Composites","authors":"Donatas Gricius, Rasa Kandrotaitė Janutienė, D. Mazeika, Rolandas Sertvytis, O. Syzonenko, A. Torpakov","doi":"10.5755/j02.mech.32230","DOIUrl":"https://doi.org/10.5755/j02.mech.32230","url":null,"abstract":"The Ti-based metal matrix composite samples are novel, fabricated by using high voltage electric discharge and spark plasma sintering processes. They have potential usage in the aviation industry. A research that allowed measuring an electrical conductivity of Ti-based composites was performed. A collinear four-point probe method was chosen for measurement of electrical conductivity. Needle-like probes were used to contact the tested sample. Other aspects of the measurement setup are discussed and selected according to relevant literature. A simulation was performed using COMSOL software to validate the measurement method. Furthermore, a simulation performed for contact force of the probes was performed. A 3D model of the measurement tool was created and designed. The measurement setup was tested and validated by using a copper sample. electrical resistance of Ti-based composite samples was measured, and electrical conductivity was calculated. Furthermore, samples were measured at different temperatures and resistivity dependence to temperature was presented. Experimental results are compared to similar research results.","PeriodicalId":54741,"journal":{"name":"Mechanika","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2023-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46717844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Pauliukaitis, L. Gegeckienė, I. Venytė, E. Kibirkštis
The linear type single-chamber pneumatic vibro- actuator is widely used in industrial automation due to its fast response, low energy consumption, and high-power density. Many researchers have conducted studies on the dynamic behaviour of pneumatic actuators to optimize their performance. A pneumatic vibroexciter with one chamber was investigated in this study. A simulation model was developed in the MATLAB environment to conduct theoretical studies. The simulation results were compared with experimental measurements previously made by the authors of this paper. The findings of this study can be utilized to optimize the design and control of pneumatic actuators in industrial automation.
{"title":"Research on a Single-Chamber Pneumatic Vibroactuator","authors":"D. Pauliukaitis, L. Gegeckienė, I. Venytė, E. Kibirkštis","doi":"10.5755/j02.mech.32570","DOIUrl":"https://doi.org/10.5755/j02.mech.32570","url":null,"abstract":"The linear type single-chamber pneumatic vibro- actuator is widely used in industrial automation due to its fast response, low energy consumption, and high-power density. Many researchers have conducted studies on the dynamic behaviour of pneumatic actuators to optimize their performance.\u0000A pneumatic vibroexciter with one chamber was investigated in this study. A simulation model was developed in the MATLAB environment to conduct theoretical studies. The simulation results were compared with experimental measurements previously made by the authors of this paper.\u0000The findings of this study can be utilized to optimize the design and control of pneumatic actuators in industrial automation.","PeriodicalId":54741,"journal":{"name":"Mechanika","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2023-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48938525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To reduce greenhouse gas emissions in dealing with climate change, raplacing fule vehicles with electric vehicles (EVs) is one of the most effective measures. The multi-motor electric drive system (MMEDS), which is widely used in EVs, is driven by two or more permanent magnet synchronous motors (PMSM) by parallel shaft gear set (PSGS). Due to the action of forced synchronization of PSGS, once there is a rotational speed difference (∆V) between PMSMs, this will break the balance of output power between PMSMs and cause the increase in output power of some PMSMs while others decrease or even become negative, and eventually generate parasitic power. Parasitic power in MMEDS is bound to cause an autoexcitation vibration and a variation in dynamic characteristics of MMEDS. Therefore, in this paper, an electro-mechanical coupled dynamic model of MMEDS is set up, including a dynaimc model of PSGS and a dynaimc model of PMSM. Then, the affect of the forced synchronization action of PSGS on the dynamic characteristic of MMEDS is investigated under different ∆V. The results show that under the action of the forced synchronization of PSGS, the output power of the PMSM with a fast speed (or a slow speed) increase (or decreases) with the increasing of ∆V, and when ∆V ≤5 rpm, the increment rate or decrement rate of the output power of PMSM is obviously greater than that when ∆V>5 rpm. Meanwhile, ∆V has a singnificant effect on the nonlinearity of the vibration of the wheel, which increases first and then decreases with ∆V increases. The dominated frequencies of dynamic meshing force (DMF) of gear pair do not change with ∆V, but their contributions to the amplitude of the DMF change with ∆V. Moreover, the modulation frequencies also appear in the spectrum of the DMF, but their contributions to the amplitude of the DMF are singnificantly less than that of the dominated frequencies
{"title":"Research on dynamic characteristics of a multi-motor electric driving system caused by parasitic power","authors":"Ruizhi Shu, Zhengqiu Xie, Shuaishuai Ge, Qin Yin, Zhengyao Zou, Rulong Tan, Jianghua Fu","doi":"10.5755/j02.mech.32097","DOIUrl":"https://doi.org/10.5755/j02.mech.32097","url":null,"abstract":" To reduce greenhouse gas emissions in dealing with climate change, raplacing fule vehicles with electric vehicles (EVs) is one of the most effective measures. The multi-motor electric drive system (MMEDS), which is widely used in EVs, is driven by two or more permanent magnet synchronous motors (PMSM) by parallel shaft gear set (PSGS). Due to the action of forced synchronization of PSGS, once there is a rotational speed difference (∆V) between PMSMs, this will break the balance of output power between PMSMs and cause the increase in output power of some PMSMs while others decrease or even become negative, and eventually generate parasitic power. Parasitic power in MMEDS is bound to cause an autoexcitation vibration and a variation in dynamic characteristics of MMEDS. Therefore, in this paper, an electro-mechanical coupled dynamic model of MMEDS is set up, including a dynaimc model of PSGS and a dynaimc model of PMSM. Then, the affect of the forced synchronization action of PSGS on the dynamic characteristic of MMEDS is investigated under different ∆V. The results show that under the action of the forced synchronization of PSGS, the output power of the PMSM with a fast speed (or a slow speed) increase (or decreases) with the increasing of ∆V, and when ∆V ≤5 rpm, the increment rate or decrement rate of the output power of PMSM is obviously greater than that when ∆V>5 rpm. Meanwhile, ∆V has a singnificant effect on the nonlinearity of the vibration of the wheel, which increases first and then decreases with ∆V increases. The dominated frequencies of dynamic meshing force (DMF) of gear pair do not change with ∆V, but their contributions to the amplitude of the DMF change with ∆V. Moreover, the modulation frequencies also appear in the spectrum of the DMF, but their contributions to the amplitude of the DMF are singnificantly less than that of the dominated frequencies","PeriodicalId":54741,"journal":{"name":"Mechanika","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2023-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44544868","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rocket targets are essential for live-fire military training. RT-400 is a short-range rocket target. This rocket must be improvised for a longer range. So, two motors are used to upgrade the range of the rocket. as the dimensions of the rocket change, it is required to analyse the nose cone shape for the prediction of forces and coefficients. With obtained values, ballistic analysis is carried out to determine the theoretical maximum range and altitudes are obtained.
{"title":"Aerodynamic and External Ballistic modelling of a Rocket Target with Two Motors in a Parallel Configuration","authors":"Hari Prasanna Manimaran, A. Fedaravičius","doi":"10.5755/j02.mech.32140","DOIUrl":"https://doi.org/10.5755/j02.mech.32140","url":null,"abstract":"Rocket targets are essential for live-fire military training. RT-400 is a short-range rocket target. This rocket must be improvised for a longer range. So, two motors are used to upgrade the range of the rocket. as the dimensions of the rocket change, it is required to analyse the nose cone shape for the prediction of forces and coefficients. With obtained values, ballistic analysis is carried out to determine the theoretical maximum range and altitudes are obtained.","PeriodicalId":54741,"journal":{"name":"Mechanika","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2023-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49036889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The biomechanical research about toothless mandible with four dental implants and a prosthetic system research, which shows the influence of the cantilever length of prosthesis on the weakest structural elements and the load changes in peri-implant bone by changing symmetrically position of the dental implants (in relation to each other), diameters and lengths, and orientation (in relation to chewing surfaces), is not discussed widely in the scientific literature. On the other hand, the use of short implants is more common in practice. Some of these implants are only 8mm in length.The odontologists, implantologists and dental technician can use results received by finite element method (FEM) in the daily clinical practice in order to reduce the potential for mechanical / technological and consequent biological complications already at the planning stage of the treatment, and thus determine best outcomes in the treatment of toothless patients.With a unique interpretation of the results obtained by FEM, the paper discusses the results of implants (8 mm in length with 3.5 mm and 4.5 mm diameter) loading, when the cantilevered dental prostheses are loaded in different positions, as well as implant positions are changed.
{"title":"A Study Case of Short Dental Implants Loading in the All-On-4® System on Fixed Dental Prostheses: A Finite Element Analysis","authors":"I. Skiedraite, S. Diliunas, Vaidas Varinauskas","doi":"10.5755/j02.mech.33221","DOIUrl":"https://doi.org/10.5755/j02.mech.33221","url":null,"abstract":"The biomechanical research about toothless mandible with four dental implants and a prosthetic system research, which shows the influence of the cantilever length of prosthesis on the weakest structural elements and the load changes in peri-implant bone by changing symmetrically position of the dental implants (in relation to each other), diameters and lengths, and orientation (in relation to chewing surfaces), is not discussed widely in the scientific literature. On the other hand, the use of short implants is more common in practice. Some of these implants are only 8mm in length.The odontologists, implantologists and dental technician can use results received by finite element method (FEM) in the daily clinical practice in order to reduce the potential for mechanical / technological and consequent biological complications already at the planning stage of the treatment, and thus determine best outcomes in the treatment of toothless patients.With a unique interpretation of the results obtained by FEM, the paper discusses the results of implants (8 mm in length with 3.5 mm and 4.5 mm diameter) loading, when the cantilevered dental prostheses are loaded in different positions, as well as implant positions are changed.","PeriodicalId":54741,"journal":{"name":"Mechanika","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2023-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47864691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
It is important to achieve high strength, high modulus of elasticity, good energy damping for lightweight armor materials. For this purpose, two or more similar or different materials are combined at the macro level. In this way, a new structure emerges that we call composite material. A composite is a new structure in which the good properties of the components in its structure become evident in the material. Research on the production and mechanical properties of composites that meet the needs of the developing technology continues. Military personnel, armored vehicles and many security elements are tested in the field with a lot of threats (such as mines, armor piercing ammunition, explosives etc.). Therefore, the armor used by security elements should be strengthened without compromising features such as lightness, cost and long-term use. This study covers the development of Kevlar's ballistic properties by impregnating Shear Thickening Fluid (STF). STF is composed of silica (AEROSIL 200) and polyethylene glycol (PEG 400). STF-impregnated Kevlar fibers have been subjected to impact testing at low and high speeds. Low-speed tests were carried out with a drop tower. High-speed tests were carried out according to NIJ 0101.06 Level II standards. The mass fraction of silica in the STF was determined as the research parameter. The change in the behavior of the materials with the change of silica ratio was investigated; Although improvements were observed in energy dissipation in low-speed impacts, it was noted that ballistic behavior improved up to a certain point, and then the improvement in behavior decreased.
{"title":"Investigation of Impact Performance of STF Impragnated Composites","authors":"Murat Berkay Zeka, A. Aytaç","doi":"10.5755/j02.mech.31069","DOIUrl":"https://doi.org/10.5755/j02.mech.31069","url":null,"abstract":"It is important to achieve high strength, high modulus of elasticity, good energy damping for lightweight armor materials. For this purpose, two or more similar or different materials are combined at the macro level. In this way, a new structure emerges that we call composite material. A composite is a new structure in which the good properties of the components in its structure become evident in the material. Research on the production and mechanical properties of composites that meet the needs of the developing technology continues. Military personnel, armored vehicles and many security elements are tested in the field with a lot of threats (such as mines, armor piercing ammunition, explosives etc.). Therefore, the armor used by security elements should be strengthened without compromising features such as lightness, cost and long-term use. This study covers the development of Kevlar's ballistic properties by impregnating Shear Thickening Fluid (STF). STF is composed of silica (AEROSIL 200) and polyethylene glycol (PEG 400). STF-impregnated Kevlar fibers have been subjected to impact testing at low and high speeds. Low-speed tests were carried out with a drop tower. High-speed tests were carried out according to NIJ 0101.06 Level II standards. The mass fraction of silica in the STF was determined as the research parameter. The change in the behavior of the materials with the change of silica ratio was investigated; Although improvements were observed in energy dissipation in low-speed impacts, it was noted that ballistic behavior improved up to a certain point, and then the improvement in behavior decreased.","PeriodicalId":54741,"journal":{"name":"Mechanika","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2023-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42331951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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