{"created":"2021-03-01T06:22:07.400850+00:00","id":5427,"links":{},"metadata":{"_buckets":{"deposit":"117fe270-ee68-4b38-85c9-32111c885537"},"_deposit":{"id":"5427","owners":[],"pid":{"revision_id":0,"type":"depid","value":"5427"},"status":"published"},"_oai":{"id":"oai:repository.dl.itc.u-tokyo.ac.jp:00005427","sets":["6:278:395","9:233:280"]},"item_7_alternative_title_1":{"attribute_name":"その他のタイトル","attribute_value_mlt":[{"subitem_alternative_title":"周期的局部振動モードと孤立局部振動モードを利用したベルトコンベアの損傷同定"}]},"item_7_biblio_info_7":{"attribute_name":"書誌情報","attribute_value_mlt":[{"bibliographicIssueDates":{"bibliographicIssueDate":"2012-09-27","bibliographicIssueDateType":"Issued"},"bibliographic_titles":[{}]}]},"item_7_date_granted_25":{"attribute_name":"学位授与年月日","attribute_value_mlt":[{"subitem_dategranted":"2012-09-27"}]},"item_7_degree_grantor_23":{"attribute_name":"学位授与機関","attribute_value_mlt":[{"subitem_degreegrantor":[{"subitem_degreegrantor_name":"University of Tokyo (東京大学)"}]}]},"item_7_degree_name_20":{"attribute_name":"学位名","attribute_value_mlt":[{"subitem_degreename":"博士(工学)"}]},"item_7_description_5":{"attribute_name":"抄録","attribute_value_mlt":[{"subitem_description":"Due to aging and corrosion, large number of belt conveyor support structures in industrial plants has degraded over the past decades. These structures are in damage condition and may cause human injury or death and economy impacts as several structural accidents of belt conveyors have been reported in Japan and overseas which caused the operation of factories to stop. Therefore, structural condition assessment of these structures is urgent. To overcome the problems of global vibration modes in damage identification (i.e. need of before-and-after comparison, incapable to be applied for structures with large number of damaged elements, considering effects of non-structural elements and environmental conditions), new damage identification methods are proposed based on two specific local vibration modes named Periodic Local Vibration Modes (PLVM) and Isolated Local Vibration Modes (ILVM). These modes are distinguished from other types of local vibration modes. PLVM is a mode in which vibrations of one group of the identical secondary members are much larger than the other members. The idea in damage identification is when one of these identical members is damaged, this member no longer vibrates in PLVM, instead, it has ILVM in a lower frequency. Numerical and experimental results show that PLVM and ILVM are better observed when each secondary member is directly hit. As an alternative method to easily observe PLVM, one of the undamaged members in each identical members set can be hit. By hitting one of the undamaged members in each identical members set, damaged secondary members of the identical members set are localized and the relative severity of damage is identified by comparing PLVM amplitude in the corresponding PLVM range. The existence of PLVM and ILVM in systems consisting of main and secondary members is investigated using mass-spring system. A 3-DOF system including coupler, main, and secondary members is considered and mode localization phenomenon is mathematically explained. Then, a more complicated lamped mass-spring system which has 21-DOF is compared with a finite element model of the support structure of a belt-conveyor to find a correspondence between these two models and the existence condition of PLVM and ILVM is numerically discussed. It is found that when main members are much stiffer than secondary members, PLVM and ILVM of secondary members exist and their frequencies are nearly the same as natural frequencies of the corresponding secondary members. Next, the method based on global vibration modes and two damage identification methods based on PLVM and ILVM frequencies comparison and PLVM amplitude comparison are utilized to identify damaged members of a finite element model of the support structure of a typical belt conveyor. Then, based on the sensitivity analyses of frequencies of PLVM and ILVM which show that the appropriate parameters in damage quantification of secondary members are the local internal connections and the properties of the corresponding member, beam theory and its applicability on the quantification of damage degree are discussed and the stiffness of local boundary conditions and the stiffness reduction of damaged members are reliably identified. Likewise, the two damage identification techniques based on PLVM and ILVM are examined for two laboratory models. One has continuous longitudinal members and the other has separated longitudinal members. The method is applicable for all secondary members (i.e. diagonal and lateral members) of the structure with continuous main members, and all damaged and undamaged members almost vibrate in their own natural frequencies; yet, these damage identification methods cannot identify the damaged lateral members of the structure with non-continuous main members since coupling of modes happens for these members. The reason is due to the fact that the stiffness of the main members is not much larger than the lateral members and no other secondary member is attached to one of the connections of each lateral member. The existence of PLVM and ILVM of the secondary members of a planar full-scale model of a belt conveyor is investigated and the damaged members are identified using the method based on PLVM and ILVM frequencies comparison. Finally, using the method based on PLVM and ILVM frequencies comparison, damaged secondary members of a real belt-conveyor are correctly localized and using beam theory, the equivalent damage degree is quantified for each damaged member while each member is directly hit and the method is experimentally verified. Moreover, using the damage identification method based on PLVM amplitude comparison, the damaged secondary members are localized and the relative severity of the damage is correctly identified. In conclusion, damage identification techniques to identify damages on belt conveyor support structures utilizing local vibration modes taking advantage of the non-contact measurement device have been proposed. These techniques are capable of identifying multiple damages on a structure without the need of before-and-after comparison. The Laser Doppler Vibrometer allows a quick assessment of damages. The applicability to belt conveyors is confirmed through numerical and experimental verifications. Further studies on criteria to distinguish local vibration modes and on the applicability to structures of other types such as truss bridges and towers are considered to advance the techniques toward their full-fledged use.","subitem_description_type":"Abstract"}]},"item_7_full_name_3":{"attribute_name":"著者別名","attribute_value_mlt":[{"nameIdentifiers":[{"nameIdentifier":"11333","nameIdentifierScheme":"WEKO"}],"names":[{"name":"ホナバシュ, アミン"}]}]},"item_7_identifier_registration":{"attribute_name":"ID登録","attribute_value_mlt":[{"subitem_identifier_reg_text":"10.15083/00005418","subitem_identifier_reg_type":"JaLC"}]},"item_7_select_21":{"attribute_name":"学位","attribute_value_mlt":[{"subitem_select_item":"doctoral"}]},"item_7_subject_13":{"attribute_name":"日本十進分類法","attribute_value_mlt":[{"subitem_subject":"536","subitem_subject_scheme":"NDC"}]},"item_7_text_22":{"attribute_name":"学位分野","attribute_value_mlt":[{"subitem_text_value":"Engineering (工学)"}]},"item_7_text_24":{"attribute_name":"研究科・専攻","attribute_value_mlt":[{"subitem_text_value":"Department of Civil Engineering, Graduate School of Engineering (工学系研究科社会基盤学専攻)"}]},"item_7_text_4":{"attribute_name":"著者所属","attribute_value_mlt":[{"subitem_text_value":"東京大学大学院工学系研究科社会基盤学専攻"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"Honarbakhsh, Amin"}],"nameIdentifiers":[{"nameIdentifier":"11332","nameIdentifierScheme":"WEKO"}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2017-06-01"}],"displaytype":"detail","filename":"20120905.pdf","filesize":[{"value":"11.2 MB"}],"format":"application/pdf","licensetype":"license_note","mimetype":"application/pdf","url":{"label":"20120905.pdf","url":"https://repository.dl.itc.u-tokyo.ac.jp/record/5427/files/20120905.pdf"},"version_id":"65d326cd-ea30-438e-8b1f-ccd155e69409"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"eng"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"thesis","resourceuri":"http://purl.org/coar/resource_type/c_46ec"}]},"item_title":"Damage Identification of Belt Conveyors Using Periodic and Isolated Local Vibration Modes","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Damage Identification of Belt Conveyors Using Periodic and Isolated Local Vibration Modes"}]},"item_type_id":"7","owner":"1","path":["280","395"],"pubdate":{"attribute_name":"公開日","attribute_value":"2013-10-02"},"publish_date":"2013-10-02","publish_status":"0","recid":"5427","relation_version_is_last":true,"title":["Damage Identification of Belt Conveyors Using Periodic and Isolated Local Vibration Modes"],"weko_creator_id":"1","weko_shared_id":null},"updated":"2022-12-19T04:50:01.989656+00:00"}