Pub Date : 2013-03-01DOI: 10.4028/www.scientific.net/AMR.668.589
Bing Chen, M. Deng, Z. Yin
The complex mode method and Galerkin method are applied to analyze natural frequency of pinned-pinned Pipe conveying fluid resting on Pasternak foundation. Compared to the exact solution obtained by the complex mode method, the influence of Galerkin modal truncation to natural frequency is elaborated here, and the influence of Pasternak foundation’s shear stiffness, spring stiffness and mass parameter to truncation error are also focused on in this paper. It is concluded that, within specified flow velocity, the increasing of Pasternak foundation’s shear stiffness and spring stiffness will reduce the truncation error produced by Galerkin method, but, comparing with the former, the latter’s influence can be ignored. It is also founded that the truncation error will increase significantly with the increasing of the mass parameter.
{"title":"Calculation Analysis of Natural Frequency of Pipe Conveying Fluid Resting on Pasternak Foundation","authors":"Bing Chen, M. Deng, Z. Yin","doi":"10.4028/www.scientific.net/AMR.668.589","DOIUrl":"https://doi.org/10.4028/www.scientific.net/AMR.668.589","url":null,"abstract":"The complex mode method and Galerkin method are applied to analyze natural frequency of pinned-pinned Pipe conveying fluid resting on Pasternak foundation. Compared to the exact solution obtained by the complex mode method, the influence of Galerkin modal truncation to natural frequency is elaborated here, and the influence of Pasternak foundation’s shear stiffness, spring stiffness and mass parameter to truncation error are also focused on in this paper. It is concluded that, within specified flow velocity, the increasing of Pasternak foundation’s shear stiffness and spring stiffness will reduce the truncation error produced by Galerkin method, but, comparing with the former, the latter’s influence can be ignored. It is also founded that the truncation error will increase significantly with the increasing of the mass parameter.","PeriodicalId":39941,"journal":{"name":"Jixie Qiangdu/Journal of Mechanical Strength","volume":"668 1","pages":"589 - 592"},"PeriodicalIF":0.0,"publicationDate":"2013-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.4028/www.scientific.net/AMR.668.589","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70643193","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}
Pub Date : 2007-01-01DOI: 10.4028/0-87849-976-8.565
W. Zhi
The damage location assurance criterion (DLAC) is extended to locate and assess damage in a circular cylindrical shell based on natural frequency sensitivities and mode shape deviations. Frequency sensitivities obtained from a defect-free finite element model are applied to calculate the theoretical frequency changes. The axial position of the damage can be easily obtained by comparing the theoretical and measured frequency changes due to damage. For the shell is axis-symmetric, additional information of mode shapes is introduced to locate the exact damage position. The damage extent can be estimated by the first order approximation method. The feasibility and practicality of the damage detection scheme are evaluated by locating and sizing damage for several damage scenarios in the free-free, simple-supports and free-clamped shells, respectively. Simulation results show that the proposed detection scheme can well locate the single or multiple positions of damage. It is also observed that damage extent can be estimated within a relatively small error. The robustness of the proposed method in the presence of measurement errors is demonstrated.
{"title":"DAMAGE DETECTION IN CIRCULAR CYLINDRICAL SHELLS BY FREQUENCY SENSITIVITIES AND MODE SHAPES","authors":"W. Zhi","doi":"10.4028/0-87849-976-8.565","DOIUrl":"https://doi.org/10.4028/0-87849-976-8.565","url":null,"abstract":"The damage location assurance criterion (DLAC) is extended to locate and assess damage in a circular cylindrical shell based on natural frequency sensitivities and mode shape deviations. Frequency sensitivities obtained from a defect-free finite element model are applied to calculate the theoretical frequency changes. The axial position of the damage can be easily obtained by comparing the theoretical and measured frequency changes due to damage. For the shell is axis-symmetric, additional information of mode shapes is introduced to locate the exact damage position. The damage extent can be estimated by the first order approximation method. The feasibility and practicality of the damage detection scheme are evaluated by locating and sizing damage for several damage scenarios in the free-free, simple-supports and free-clamped shells, respectively. Simulation results show that the proposed detection scheme can well locate the single or multiple positions of damage. It is also observed that damage extent can be estimated within a relatively small error. The robustness of the proposed method in the presence of measurement errors is demonstrated.","PeriodicalId":39941,"journal":{"name":"Jixie Qiangdu/Journal of Mechanical Strength","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2007-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70641053","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}
Pub Date : 2006-01-01DOI: 10.4028/0-87849-456-1.1948
Zheng Xi
Load response and failure modes of three-dimensional four-directional braided composite lugs were studied analytically and experimentally. The objective of the study was to get information on the stiffness, strength and failure mode of the lug, as well as on the applicability of the analysis method used to predict lug load response and failure. The analyses were performed using finite element method. Parabolic solid brick elements were used. A steel pin was modeled to apply the loading. The loading was applied with a constant force distribution through the center of the pin. A contact was defined between the pin and the surrounding lug surface. The test lugs were manufactured with the resin transfer molding (RTM) technique. The test specimens were loaded parallel to the lug centerline. Two types of specimens were tested. There are three basic failure modes in braided composite joints: net-tension, shear-out, and bearing. Net-tension failure is associated with matrix and fiber tension failure due to stress concentrations. Shear-out and bearing failures result primarily from the shear and compression failures of fiber and matrix. The measured strains showed fairly good correlation with the analysis results. The strain response was almost linear. It can be concluded that with correct material properties the FE(finite element) approach used in the analyses can provide a reasonable estimate for the load response and failure of 3-d braided composite lugs.
{"title":"STRENGTH PREDICATION FOR LOAD-BEARING JOINTS OF THREE-DIMENSIONAL BRAIDED COMPOSITES","authors":"Zheng Xi","doi":"10.4028/0-87849-456-1.1948","DOIUrl":"https://doi.org/10.4028/0-87849-456-1.1948","url":null,"abstract":"Load response and failure modes of three-dimensional four-directional braided composite lugs were studied analytically and experimentally. The objective of the study was to get information on the stiffness, strength and failure mode of the lug, as well as on the applicability of the analysis method used to predict lug load response and failure. The analyses were performed using finite element method. Parabolic solid brick elements were used. A steel pin was modeled to apply the loading. The loading was applied with a constant force distribution through the center of the pin. A contact was defined between the pin and the surrounding lug surface. The test lugs were manufactured with the resin transfer molding (RTM) technique. The test specimens were loaded parallel to the lug centerline. Two types of specimens were tested. There are three basic failure modes in braided composite joints: net-tension, shear-out, and bearing. Net-tension failure is associated with matrix and fiber tension failure due to stress concentrations. Shear-out and bearing failures result primarily from the shear and compression failures of fiber and matrix. The measured strains showed fairly good correlation with the analysis results. The strain response was almost linear. It can be concluded that with correct material properties the FE(finite element) approach used in the analyses can provide a reasonable estimate for the load response and failure of 3-d braided composite lugs.","PeriodicalId":39941,"journal":{"name":"Jixie Qiangdu/Journal of Mechanical Strength","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2006-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70640854","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}
Pub Date : 2004-01-01DOI: 10.4028/0-87849-413-8.347
Jiang Zhi
According to principle of damage mechanics, the damage characteristics of ferrite nodular cast iron under uniaxial stress has been studied through measuring electric resistance. The results showed that the damage in nodular cast iron happens when the applied stress is more than a certain extent, and the damage value increases with stress. The evolutional law of damage value as a function of stress was obtained. The damage threshold of nodular cast iron exists and increases with nodularity, but this threshold is always below the yield strength, which has related significant reference to the design of machinery structure and the choice of materials. The critical damage value is not related to the nodularity, which is about 0.06～0.068 under the present test condition.
{"title":"STUDY ON CHARACTERISTICS OF DAMAGE MECHANICS FOR DUCTILE IRON","authors":"Jiang Zhi","doi":"10.4028/0-87849-413-8.347","DOIUrl":"https://doi.org/10.4028/0-87849-413-8.347","url":null,"abstract":"According to principle of damage mechanics, the damage characteristics of ferrite nodular cast iron under uniaxial stress has been studied through measuring electric resistance. The results showed that the damage in nodular cast iron happens when the applied stress is more than a certain extent, and the damage value increases with stress. The evolutional law of damage value as a function of stress was obtained. The damage threshold of nodular cast iron exists and increases with nodularity, but this threshold is always below the yield strength, which has related significant reference to the design of machinery structure and the choice of materials. The critical damage value is not related to the nodularity, which is about 0.06～0.068 under the present test condition.","PeriodicalId":39941,"journal":{"name":"Jixie Qiangdu/Journal of Mechanical Strength","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2004-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70640685","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}
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