Abstract
An experimental and numerical research program is executed to investigate the fatigue lifetime increase due to grinding-type post-weld treatment method. Plate edge gusset, longitudinal attachment and T-type joint specimens are investigated using fatigue test results, numerical models and mathematical statistical tools. The favourable impact of grinding on fatigue lifetime of the analysed joints is commonly known for researchers. However, considering the lifetime increasing effect is mainly based on experimental results. In the current research program, numerical models for as-welded and post-weld-treated specimens are developed and the lifetime increasing effect of weld treatment is investigated using effective notch stress (ENS) method. Fatigue tests are executed on as-welded and weld-treated specimens, and their results are comparatively evaluated based on numerical calculations and measured lifetimes. The results prove that the fatigue lifetime of weld treated (ground) details can be predicted with high accuracy by applying modified weld geometry in the numerical model and ENS method. Based on the current investigation, it is proved that the advantage of weld geometry treatment method comes mainly from the modification of the weld geometry at the fatigue critical point. Results also show that the same S-N curve can be applied for both as-welded and ground specimens, if the modified weld geometry is implemented in the numerical model.
Highlights
Nowadays, as a consequence of the production cost reduction of high-strength steels (HSS) their application increases in the practice of structural engineering as well.Weld World (2020) 64:1033–1046 structures made of HSS can be economical in numerous cases, the fatigue behaviour of HSS structures is the barrier of their wide application in fatigue-sensitive structures, like bridges
These results prove that the effective notch stress method is a useful tool to investigate the fatigue lifetime of post-weld-treated specimens as well as using the modified weld geometry in the numerical model
Effective notch stress method seems to be an effective tool to investigate the as-welded and the disc ground specimens as well; same S-N curve could be used for both specimen types if the weld geometry is modified in the numerical model
Summary
As a consequence of the production cost reduction of high-strength steels (HSS) their application increases in the practice of structural engineering as well. To utilize the benefits of HSS material, post-weld treatment (PWT) methods were developed in the past to improve the fatigue lifetime of fatiguesensitive structural details. Residual stresses can be modified by thermal methods, like spot heating or thermal stress relief, or mechanical methods, like shot peening or high frequency impact treatment. Another type of PWTs is the weld geometry improvement method. Results are compared to investigate the effect of grinding on the fatigue lifetime and applicability of the effective notch stress method is discussed considering post weld treatment methods
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