Fatigue Life and Crack Initiation in Monopile Foundation by Fatigue FE Analysis
Round 1
Reviewer 1 Report
Intro: the first paragraph merely lists several papers about mechanics and dynamics of monopile and fail to highlight the research need and contribution of this manuscript to this field.
Table 2: where are the material constants derived from? It seems like the authors may derive these constants from the MTS tests, if so, please consider changing the section title to make it more specific.
Figure 3: the legend seems to be irrelevant to the figure.
Figure 6: as two welding locations were modelled, why are there two dozens of temperature curves in panel b?
Title of section 4.2: typo: "fatihue"
The second and third paragraphs of section 4.2 are completely the same.
Line 332: fail to understand the sentence with grammar errors.
Line 337: why a difference between the IIW recommendation and experimental data from other people's work (refs 24 & 27) implies "reliable" FE model presented in this study? This could be the main contribution of this study and therefore needs to be carefully elaborated.
Figure 13: the line for DND-V is missing
Other comments:
The current manuscript is poorly organized as Sections 2-4 describe both methods and results. The author may consider moving supportive work, such as deriving the material constants in section 2, to the supplementary material.
All the abbreviations need to be defined at its first appearance.
In the Abstract: please use the full name instead of abbreviations (CDM, DNV-GL)
Author Response
- The authors wish to thank the reviewer for their detailed comments and suggestions, which certainly have helped us improve the paper's quality.
- We have also done a english proofreading from the writting center of Chung-Ang university.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This manuscript aims at predicting the fatigue life and crack initiation of monopile off-shore structure by incorporating the effects caused by weld-induced residual stresses, deformations, and cyclic loading.
After analyzing the manuscript entitled "Fatigue Life and Crack Initiation in Monopile Foundation by 2 Fatigue FE-Analysis" submitted for review, it was noticed:
1. there are abbreviations/acronyms in the steszn that have not been previously defined - the first time they are used, they need to be clarified
2. figure 1 - needs a major revision, part (a) inaccurate resolution of the photo, part (b) dimensioning is done based on the principles of technical drawing, not a 3D model, part (d) Why the X axis (time) is not described?
3. figure 3 - incorrect description of the drawing, dimensioning also needs improvement, it is unreadable
4. figure 6. captions (a) and (b) in part (a) of the drawing make it difficult to perceive the drawing - maybe you should label it 'zone 1' and 'zone 2'?
5. "By 3D fatihue FE analysis". - 'fatigue' typo
6. why was cyclic load chosen as a triangular signal? Is it a good reflection of reality?
7. the paper lacked an indication of the fit of the cyclic plasticity curve (isotropic/hardening rates) against the experimental result
8.There is a lack of information on how the FEA analysis was prepared, how exactly the initial conditions were defined, whether model calibration was carried out, whether convergence of the solution was studied, what elements (type) and in what size finite elements were used?
9 The conclusions of the study are very general, the conclusions should be made more precise and the element of scientific novelty in this manuscript should be highlighted.
10. the crack initiation analysis part of the manuscript needs to be expanded. Crack initiation placed in the title suggests realizing this issue in more detail.
The manuscript in this form is not suitable for publication in Processes journal
Author Response
- The authors wish to thank the reviewers for their detailed comments and suggestions , which certainly have helped us improve the paper's quality.
- We have also done a english proofreading from the writing center of Chung-Ang university.
Author Response File: Author Response.pdf
Reviewer 3 Report
The authors have utilized a finite element analysis to predict the fatigue life and the crack initiation of the welded monopile substructure.
The fatigue crack initiation and the fatigue life results are compared against theoretical equations and DNV-GL standards which are seemed to be useful for engineering practice. The study is novel in nature and adequate explanations have been provided by the authors. There are a few comments which if the authors address will contribute to the improvement of the paper.
1. Please add the test environment condition of experiment listed in the Section 2.
2. The mesh sensitivity analysis should be made for the component shown in Fig. 4.
3. The details source for the temperature-dependent mechanical material properties data should be clarified due to their importance to the model accuracy evaluation.
Author Response
- The authors wish to thank the reviewers for their detailed comments and suggestions , which certainly have helped us improve the paper's quality.
- We have also done a english proofreading from the writing center of Chung-Ang university.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The reviewer appreciates the effort the authors invested in revising, especially in English writing.
The authors may consider increase the font size in figures (especially Figs. 3 and 8) to make them readable.
Author Response
Thank you for your comments and suggestions which certainly have helped us to improve the quality of the paper.
Author Response File: Author Response.pdf
Reviewer 2 Report
I accept the replies to the previous review. I accept the revised manuscript as it is suitable for publication in the journal Processes in its current form.
Author Response
Thank you for your comments and suggestions which certainly have helped us to improve the quality of the paper.
Author Response File: Author Response.pdf
Reviewer 3 Report
It is agreed for author's response.
Round 3
Reviewer 1 Report
Thanks for the revision. I recommend accepting.
