Abstract In this paper the concept of generalized form of proportional damping is proposed. Classical modal analysis of non-conservative continua is extended to multi DOF linear dynamic systems with asymmetric matrices. Mode orthogonality relationships have been generalized to non-conservative systems. Several discretization methods of continua are presented. Finally, an expression for derivatives of eigenvalues and eigenvectors of non-conservative system is presented. Examples are provided to illustrate the proposed methods.
{"title":"Dynamic and Sensitivity Analysis General Non-Conservative Asymmetric Mechanical Systems","authors":"M. Zmindak","doi":"10.2478/scjme-2018-0021","DOIUrl":"https://doi.org/10.2478/scjme-2018-0021","url":null,"abstract":"Abstract In this paper the concept of generalized form of proportional damping is proposed. Classical modal analysis of non-conservative continua is extended to multi DOF linear dynamic systems with asymmetric matrices. Mode orthogonality relationships have been generalized to non-conservative systems. Several discretization methods of continua are presented. Finally, an expression for derivatives of eigenvalues and eigenvectors of non-conservative system is presented. Examples are provided to illustrate the proposed methods.","PeriodicalId":35968,"journal":{"name":"Strojnicky Casopis","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48824257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Murín, M. Aminbaghai, V. Goga, V. Kutǐs, Juraj Paulech, J. Hrabovský
Abstract In this paper, results of numerical simulations and measurements are presented concerning the non-uniform torsion and bending of an angled members of hollow cross-section. In numerical simulation, our linear-elastic 3D Timoshenko warping beam finite element is used, which allows consideration of non-uniform torsion. The finite element is suitable for analysis of spatial structures consisting of beams with constant open and closed cross-sections. The effect of the secondary torsional moment and of the shear forces on the deformation is included in the local finite beam element stiffness matrix. The warping part of the first derivative of the twist angle due to bimoment is considered as an additional degree of freedom at the nodes of the finite elements. Standard beam, shell and solid finite elements are also used in the comparative stress and deformation simulations. Results of the numerical experiments are discussed, compared, and evaluated. Measurements are performed for confirmation of the calculated results.
{"title":"Effect of Non-Uniform Torsion on Elastostatics of a Frame of Hollow Rectangular Cross-Section","authors":"J. Murín, M. Aminbaghai, V. Goga, V. Kutǐs, Juraj Paulech, J. Hrabovský","doi":"10.2478/scjme-2018-0016","DOIUrl":"https://doi.org/10.2478/scjme-2018-0016","url":null,"abstract":"Abstract In this paper, results of numerical simulations and measurements are presented concerning the non-uniform torsion and bending of an angled members of hollow cross-section. In numerical simulation, our linear-elastic 3D Timoshenko warping beam finite element is used, which allows consideration of non-uniform torsion. The finite element is suitable for analysis of spatial structures consisting of beams with constant open and closed cross-sections. The effect of the secondary torsional moment and of the shear forces on the deformation is included in the local finite beam element stiffness matrix. The warping part of the first derivative of the twist angle due to bimoment is considered as an additional degree of freedom at the nodes of the finite elements. Standard beam, shell and solid finite elements are also used in the comparative stress and deformation simulations. Results of the numerical experiments are discussed, compared, and evaluated. Measurements are performed for confirmation of the calculated results.","PeriodicalId":35968,"journal":{"name":"Strojnicky Casopis","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44239243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Al-Mg-Mn-Sc-Zr alloy plates of 5mm thick were welded successfully using Friction stir welding (FSW). Three-factor five-level central composite design was adopted for experimentation. Response surface methodology (RSM) was employed to construct a mathematical regression model. Optimization of FSW process parameters obtained by using response surface plots for maximize hardness, tensile strength, %elongation, impact strength and bending strength, the results were validated with confirmation tests at identified optimum conditions.
{"title":"Optimization of Process Parameters for FSW of Al-Mg-Mn-Sc-Zr Alloy Using CCD And RSM","authors":"M. S. Srinivasa Rao, N. Ramanaiah","doi":"10.2478/scjme-2018-0035","DOIUrl":"https://doi.org/10.2478/scjme-2018-0035","url":null,"abstract":"Abstract Al-Mg-Mn-Sc-Zr alloy plates of 5mm thick were welded successfully using Friction stir welding (FSW). Three-factor five-level central composite design was adopted for experimentation. Response surface methodology (RSM) was employed to construct a mathematical regression model. Optimization of FSW process parameters obtained by using response surface plots for maximize hardness, tensile strength, %elongation, impact strength and bending strength, the results were validated with confirmation tests at identified optimum conditions.","PeriodicalId":35968,"journal":{"name":"Strojnicky Casopis","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49668692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. C. Moi, P. K. Pal, A. Bandyopadhyay, R. Rudrapati
Abstract Weld quality mainly depends on the weld bead geometry and mechanical-metallurgical characteristics of the welded joint which has a direct relationship with the type of welding process being used and its input process parameters i.e. welding current, arc voltage, travel speed etc. In the present study, determination of tungsten inert gas (TIG) welding input parameters for achieving maximum tensile strength of 316L austenitic stainless steel is investigated. Box-Behnken design of response surface methodology has been employed to formulate the experimental plan to identify the effect of process parameters on tensile strength. Square butt joint configuration has been made using three factors - three levels of welding input parameters. Joint strength has been evaluated by notch tensile strength (NTS) and Unnotch tensile strength (UTS) method and correlated with microstructure and micro hardness of the weld. The results indicate that gas flow rate has greater influence on both NTS and UTS followed by welding current.
{"title":"Determination of Tungsten Inert Gas Welding Input Parameters to Attain Maximum Tensile Strength of 316L Austenitic Stainless Steel","authors":"S. C. Moi, P. K. Pal, A. Bandyopadhyay, R. Rudrapati","doi":"10.2478/scjme-2018-0037","DOIUrl":"https://doi.org/10.2478/scjme-2018-0037","url":null,"abstract":"Abstract Weld quality mainly depends on the weld bead geometry and mechanical-metallurgical characteristics of the welded joint which has a direct relationship with the type of welding process being used and its input process parameters i.e. welding current, arc voltage, travel speed etc. In the present study, determination of tungsten inert gas (TIG) welding input parameters for achieving maximum tensile strength of 316L austenitic stainless steel is investigated. Box-Behnken design of response surface methodology has been employed to formulate the experimental plan to identify the effect of process parameters on tensile strength. Square butt joint configuration has been made using three factors - three levels of welding input parameters. Joint strength has been evaluated by notch tensile strength (NTS) and Unnotch tensile strength (UTS) method and correlated with microstructure and micro hardness of the weld. The results indicate that gas flow rate has greater influence on both NTS and UTS followed by welding current.","PeriodicalId":35968,"journal":{"name":"Strojnicky Casopis","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44215641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract In the first quarter of the last century hydraulic power plants were equipped with high-speed Francis turbines even in the situation when a contemporary project manager would suggest Kaplan turbine. The reason is simple. Mr. Kaplan patented his turbine only in 1912 [1], https://en.wikipedia.org/wiki/Viktor_Kaplan . Those high-speed Francis turbines have just reached their lifetime. Mainly runners need repair. Our customers’ respond is that even renowned firms refuse to deliver runners with better parameters. Offer is to replace whole turbine with Kaplan or to make a copy of the existing runner. This paper presents experience and results of such a high-speed runner design. The runner substituted the one of Prokopa & sons from 1939 in powerhouse and mill at Křemže stream. Virtual prototyping technique has been used.
{"title":"Do not be Afraid of Small High-Speed Francis Turbines","authors":"Koudelka Libor","doi":"10.2478/scjme-2018-0030","DOIUrl":"https://doi.org/10.2478/scjme-2018-0030","url":null,"abstract":"Abstract In the first quarter of the last century hydraulic power plants were equipped with high-speed Francis turbines even in the situation when a contemporary project manager would suggest Kaplan turbine. The reason is simple. Mr. Kaplan patented his turbine only in 1912 [1], https://en.wikipedia.org/wiki/Viktor_Kaplan . Those high-speed Francis turbines have just reached their lifetime. Mainly runners need repair. Our customers’ respond is that even renowned firms refuse to deliver runners with better parameters. Offer is to replace whole turbine with Kaplan or to make a copy of the existing runner. This paper presents experience and results of such a high-speed runner design. The runner substituted the one of Prokopa & sons from 1939 in powerhouse and mill at Křemže stream. Virtual prototyping technique has been used.","PeriodicalId":35968,"journal":{"name":"Strojnicky Casopis","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46670307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract In the present work, static settled concentration, pH and viscosity of bottom ash is studied with addition of additive. Sodium sulfate is used as an additive with proportion of 0.2, 0.4 and 0.6% (by weight). The solid concentration of bottom ash suspension varied from 20 to 50% (by weight). Remarkable improvement has been observed in static settled concentration, pH and viscosity with addition of sodium sulfate with proportion of 0.4%. Reduction in relative viscosity is highly pronounced at higher solid concentration. Similar observation has been reported for static settled concentration and pH of slurry suspension. Addition of additive in bottom ash suspension improves the rheological characteristics which can be beneficial for conveying bottom ash slurry suspension at higher concentration.
{"title":"Effect of Additives on Static Settled Concentration, pH and Viscosity of Bottom Ash-Water Suspension","authors":"Kaushal Kumar, Satish Kumar, Ajay Kumar","doi":"10.2478/scjme-2018-0026","DOIUrl":"https://doi.org/10.2478/scjme-2018-0026","url":null,"abstract":"Abstract In the present work, static settled concentration, pH and viscosity of bottom ash is studied with addition of additive. Sodium sulfate is used as an additive with proportion of 0.2, 0.4 and 0.6% (by weight). The solid concentration of bottom ash suspension varied from 20 to 50% (by weight). Remarkable improvement has been observed in static settled concentration, pH and viscosity with addition of sodium sulfate with proportion of 0.4%. Reduction in relative viscosity is highly pronounced at higher solid concentration. Similar observation has been reported for static settled concentration and pH of slurry suspension. Addition of additive in bottom ash suspension improves the rheological characteristics which can be beneficial for conveying bottom ash slurry suspension at higher concentration.","PeriodicalId":35968,"journal":{"name":"Strojnicky Casopis","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44927148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Classical analysis methods are applied to show how flexural deflections due to shear strain in the flange pack produce bending moments and tensile loads on bolts within preloaded bolted joints. It was found that in joints made with long bolts these loads can be significant. The loads can cause yielding of the bolt, reducing bolt preload. The methods presented are adequate to demonstrate the structural integrity of joints made with long bolts or with a small footprint.
{"title":"Analysis of Bolt Bending in Preloaded Bolted Joints","authors":"M. Welch","doi":"10.2478/scjme-2018-0034","DOIUrl":"https://doi.org/10.2478/scjme-2018-0034","url":null,"abstract":"Abstract Classical analysis methods are applied to show how flexural deflections due to shear strain in the flange pack produce bending moments and tensile loads on bolts within preloaded bolted joints. It was found that in joints made with long bolts these loads can be significant. The loads can cause yielding of the bolt, reducing bolt preload. The methods presented are adequate to demonstrate the structural integrity of joints made with long bolts or with a small footprint.","PeriodicalId":35968,"journal":{"name":"Strojnicky Casopis","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44485161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Welding is a complex technological process in which local heating takes place up to the melting point of the connecting and the additional material. Phase and crystallization processes are a strong non-linear function of the cooling rate. This non-linear function multiplies the complexity of the numerical simulation and optimization of the welding process. Lately, optimization with genetic algorithm has become the trend to optimize systems that behave in a non-linear manner and contain a number of local extremes. Genetic algorithm is therefore a method by which we seek an absolute extreme. It is a method which seeks a solution to near absolute extreme. In this paper the use of the genetic algorithm for welding process optimization is described.
{"title":"Optimization of Welding Process using a Genetic Algorithm","authors":"P. Élesztős, R. Janco, Vladimír Voštiar","doi":"10.2478/scjme-2018-0014","DOIUrl":"https://doi.org/10.2478/scjme-2018-0014","url":null,"abstract":"Abstract Welding is a complex technological process in which local heating takes place up to the melting point of the connecting and the additional material. Phase and crystallization processes are a strong non-linear function of the cooling rate. This non-linear function multiplies the complexity of the numerical simulation and optimization of the welding process. Lately, optimization with genetic algorithm has become the trend to optimize systems that behave in a non-linear manner and contain a number of local extremes. Genetic algorithm is therefore a method by which we seek an absolute extreme. It is a method which seeks a solution to near absolute extreme. In this paper the use of the genetic algorithm for welding process optimization is described.","PeriodicalId":35968,"journal":{"name":"Strojnicky Casopis","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43226798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract In this paper, effects of the defect in an adhesively bonded joint have been investigated using cohesive zone modeling. Consequently, a 3D finite element model of a single lap-joint is constructed and validated with experiments. Strength prediction of current model is found desirable. Accordingly, different sizes of square shape defects are imported to model in the form of changing (raised or degraded) material properties (heterogeneity) and locally delaminated areas (as inclusion/void), respectively. Joint strength is investigated and a stress analysis is carried out for adhesive layer and adherends. Obtained Results show that, defect has significant impact on the results. It is found that at constant size of defect, local delamination has more impact on bonded joint strength than the heterogeneity. Furthermore, stress analyses demonstrate that the stress field does not change in adherends by taking defects into account. However, stress values decrease with degraded material properties and joint’s strength. Through evaluation of peel and transverse shear stresses in adhesive layer it is found that there is a change of stress distribution for both types of defects. Whereas, there is a considerable stress concentration in the delaminated adhesive layer.
{"title":"Investigation of Defect Effects on Adhesively Bonded Joint Strength Using Cohesive Zone Modeling","authors":"Jamal-Omidi Majid, Mohammadi Suki Mohammad Reza","doi":"10.2478/scjme-2018-0023","DOIUrl":"https://doi.org/10.2478/scjme-2018-0023","url":null,"abstract":"Abstract In this paper, effects of the defect in an adhesively bonded joint have been investigated using cohesive zone modeling. Consequently, a 3D finite element model of a single lap-joint is constructed and validated with experiments. Strength prediction of current model is found desirable. Accordingly, different sizes of square shape defects are imported to model in the form of changing (raised or degraded) material properties (heterogeneity) and locally delaminated areas (as inclusion/void), respectively. Joint strength is investigated and a stress analysis is carried out for adhesive layer and adherends. Obtained Results show that, defect has significant impact on the results. It is found that at constant size of defect, local delamination has more impact on bonded joint strength than the heterogeneity. Furthermore, stress analyses demonstrate that the stress field does not change in adherends by taking defects into account. However, stress values decrease with degraded material properties and joint’s strength. Through evaluation of peel and transverse shear stresses in adhesive layer it is found that there is a change of stress distribution for both types of defects. Whereas, there is a considerable stress concentration in the delaminated adhesive layer.","PeriodicalId":35968,"journal":{"name":"Strojnicky Casopis","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45370546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Dimić, Ž. Mišković, R. Mitrović, M. Ristivojević, Z. Stamenic, J. Danko, J. Bucha, T. Milesich
Abstract The advanced development of additive technologies over the past years led to the fact that parts made by these technologies have been increasingly used in the most diverse engineering applications. One of the most famous and the most applied additive technology is 3D printing. In this paper the influence of the material type on the operational characteristics of spur gears manufactured by the 3D printing technology is analyzed, after the experimental testing performed on a back to back gear test rig, in the predefined laboratory conditions.
{"title":"The Influence of Material on the Operational Characteristics of Spur Gears Manufactured by the 3D Printing Technology","authors":"A. Dimić, Ž. Mišković, R. Mitrović, M. Ristivojević, Z. Stamenic, J. Danko, J. Bucha, T. Milesich","doi":"10.2478/scjme-2018-0039","DOIUrl":"https://doi.org/10.2478/scjme-2018-0039","url":null,"abstract":"Abstract The advanced development of additive technologies over the past years led to the fact that parts made by these technologies have been increasingly used in the most diverse engineering applications. One of the most famous and the most applied additive technology is 3D printing. In this paper the influence of the material type on the operational characteristics of spur gears manufactured by the 3D printing technology is analyzed, after the experimental testing performed on a back to back gear test rig, in the predefined laboratory conditions.","PeriodicalId":35968,"journal":{"name":"Strojnicky Casopis","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44676819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：