Application of FE-analysis in Design and Verification of Bolted Joints According to VDI 2230 at CERN
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This thesis investigates how finite element analysis (FEA) can be used to simplify and improve analysis of bolted joints according to the guideline VDI 2230. Some aspects of how FEA can be applied to aid design and verification of bolted joints are given in the guideline, but not in a streamlined way that makes it simple and efficient to apply. The scope of this thesis is to clarify how FEA and VDI 2230 can be combined in analysis of bolted joints, and to present a streamlined workflow. The goal is to lower the threshold for carrying out such combined analysis. The resulting benefits are improved analysis validity and quality, and improved analysis efficiency. A case from the engineering department at CERN, where FEA has been used in analysis of bolted joints is used as basis to identify challenges in combining FEA and VDI 2230. This illustrates the need for a streamlined analysis strategy and well described workflow. The case in question is the Helium vessel (pressure vessel) for the DQW Crab Cavities, which is an important part of the High Luminosity upgrade of LHC (HL-LHC). Investigations are performed into prying, a relevant source of non-linear bolt loads and unpredictable load development, to understand the phenomenon and influence of preload. A complete analysis framework is then presented, which consist of a streamlined basic workflow, associated calculation template, details of more advanced verifications, a detailed guide with best practices and references, examples where the analysis framework has been applied, and a seminar to educate relevant personnel. In the end, suggestions and recommendations are provided for a potential revision of the Helium vessel analysis. The hope is that this thesis can be used as a resource in analysis of bolted joints using VDI 2230 and FEA, and that it will benefit the engineering department at CERN and other relevant users.