Zhu, Jiangchao (2023)
Structural Integrity Assessment of Metallic Components Based on Representative Specimens.
Technische Universität Darmstadt
doi: 10.26083/tuprints-00024511
Ph.D. Thesis, Primary publication, Publisher's Version
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Item Type: | Ph.D. Thesis | ||||
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Type of entry: | Primary publication | ||||
Title: | Structural Integrity Assessment of Metallic Components Based on Representative Specimens | ||||
Language: | English | ||||
Referees: | Vormwald, Prof. Dr. Michael ; Zerbst, Prof. Dr. Uwe | ||||
Date: | 28 September 2023 | ||||
Place of Publication: | Darmstadt | ||||
Collation: | III, IV, 164 Seiten | ||||
Date of oral examination: | 17 July 2023 | ||||
DOI: | 10.26083/tuprints-00024511 | ||||
Abstract: | Safety relevant components, for which a failure in service could have catastrophic consequences, are usually designed for extremely low probability of failure and they are subjected to stringent part qualification procedures according to guidelines set by regulatory agencies. Manufacturers are often pushed to perform tests on full scale or scaled components to ensure the structural integrity under defined loading conditions, which are usually more severe than those expected in-service. This is usually related to a huge experimental and financial effort. Therefore, companies try to develop new strategies such as digital twins, which allow to reduce costs massively, without compromising safety. This work aims at introducing a new structural integrity assessment procedure, the main idea of which is to replace, or at least reduce, the experimental testing on components by designing specimens representative of the component, having the major benefit to be tested on conventional lab testing machines under quasi-static conditions. The effectiveness of the methodology is demonstrated on an industrial case study, namely the structural integrity of a Ni base superalloy disk used in gas turbine aero-engines at overspeed conditions. Firstly, the most stressed sites in the component under combined thermo-mechanical loads have been identified by numerical analyses. The maximum permissible defect defined by regulatory agencies has been introduced at the critical locations to calculate the crack-tip parameters to be used for the representative specimen design. Fracture mechanics specimens have been designed iteratively by numerical simulations to match the stress state including the constraint conditions and the crack-tip loading parameters determined on the component. An extensive experimental campaign has been conducted on representative specimens to determine the failure modes (ductile tearing or plastic collapse). The information about the stable crack extension have been determined post-mortem by fractographic analyses and used in conjunction with dedicated numerical analyses to determine the crack growth resistance curves (R-curves). These have been used in the frame of an analytical flaw assessment procedure based on the CDF philosophy according to the European SINTAP procedure, in order to predict the failure modes and the corresponding critical loads. The results are in good agreement with the experimental tests and show the potential of the presented methodology to predict failures in metallic components. |
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Status: | Publisher's Version | ||||
URN: | urn:nbn:de:tuda-tuprints-245119 | ||||
Classification DDC: | 600 Technology, medicine, applied sciences > 620 Engineering and machine engineering | ||||
Divisions: | 13 Department of Civil and Environmental Engineering Sciences > Institute of Steel Constructions and Material Mechanics 13 Department of Civil and Environmental Engineering Sciences > Institute of Steel Constructions and Material Mechanics > Material Mechanics |
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Date Deposited: | 28 Sep 2023 12:04 | ||||
Last Modified: | 29 Sep 2023 07:13 | ||||
URI: | https://tuprints.ulb.tu-darmstadt.de/id/eprint/24511 | ||||
PPN: | 511960581 | ||||
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