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a variant of Persson's wear theory based on fatigue initiation
In reply to A new interesting theory by Persson on wear commented
I have generated a variant of recent Persson wear theory centered in fatigue initiation. We could join forces with fatigue people to make progress in this problem of wear, which is difficult but also central in tribology https://www.researchgate.net/publication/387455831_Wear_due_to_fatigue_initiation/ regardsmike
to test your "equation", we tried various damping factor
dear Xi Chen
to test if your equation can give reasonable prediction of actual experimental data, even assuming ANY value for the damping coefficient c which you suggest should be tested experimentally, we changed the value of c by several orders of magnitude with respect to the value we reported in Appendix B of https://arxiv.org/pdf/2411.03182, and the theory simply can never work, unfortunately. You can find this attempt in the main post, where I have added a figure as an attachment.
Sorry!
MC
very strange derivation of a (non) theory then!
dear Xi Chen
many thanks for your reply. If I understand correctly, you did recognize the crucial role of viscoelastic dissipation at the tip of contact, ruled by Gent and Schultz law, which is why you spend a lot of equations and of figures about that. However, when it came to obtain an estimate of pull-off, you were not able to obtain the effect of Gent and Schultz constants in the model, and hence put everything together in a coefficient of damping c. Even assuming this is correct and "c" could be really constant across various amplitudes and frequencies of excitement (which I doubt because of the non linearity of the Gent Schultz law), this is not a predictive model, because as I said you cannot estimate what is "c" as function of the crucial Gent Schultz properties in the model.
We have more comments on your paper on Appendix B of https://arxiv.org/pdf/2411.03182
regards, Mike
Altmetric and BlueSky
In reply to Moving to Bluesky
Effective today, Altmetric is tracking mentions on BlueSky:
https://bsky.social/about/blog/12-03-2024-altmetric
Mentions on BlueSky will now contribute to a publication's altmetric score.
Testing and viscoelastic
In reply to Modeling viscoelasticity–viscoplasticity of high-strain composites for space deployable structures
Testing and viscoelastic modeling of high-strain composites by NASA and its collaborators:
https://doi.org/10.2514/1.J055041
https://doi.org/10.2514/6.2022-1120
https://doi.org/10.2514/6.2022-1117
https://doi.org/10.2514/6.2021-0195
https://doi.org/10.1016/j.compstruct.2022.115376
https://doi.org/10.1016/j.actaastro.2023.12.042
Previous plastic/viscoplastic constitutive models for composites:
https://doi.org/10.1177/002199838902301004
https://doi.org/10.2514/3.59922
Testing and viscoelastic
In reply to Modeling viscoelasticity–viscoplasticity of high-strain composites for space deployable structures
Testing and viscoelastic modeling of high-strain composites by NASA and its collaborators:
https://doi.org/10.2514/1.J055041
https://doi.org/10.2514/6.2022-1120
https://doi.org/10.2514/6.2022-1117
https://doi.org/10.2514/6.2021-0195
https://doi.org/10.1016/j.compstruct.2022.115376
https://doi.org/10.1016/j.actaastro.2023.12.042
Previous plastic/viscoplastic constitutive models for composites:
https://doi.org/10.1177/002199838902301004
https://doi.org/10.2514/3.59922
Testing and viscoelastic
In reply to Modeling viscoelasticity–viscoplasticity of high-strain composites for space deployable structures
Testing and viscoelastic modeling of high-strain composites by NASA and its collaborators:
https://doi.org/10.2514/1.J055041
https://doi.org/10.2514/6.2022-1120
https://doi.org/10.2514/6.2022-1117
https://doi.org/10.2514/6.2021-0195
https://doi.org/10.1016/j.compstruct.2022.115376
https://doi.org/10.1016/j.actaastro.2023.12.042
Previous plastic/viscoplastic constitutive models for composites:
https://doi.org/10.1177/002199838902301004
https://doi.org/10.2514/3.59922
Reply to Michael's comment
Dear Michael:
Thank you for your interest in our work. Perhaps we didn't specify the parameter space explicitly in our work. The model is intended to explain parallel experiment in a simple way, and thus necessary simplification and assumption are needed. Here is our reply: https://www.researchgate.net/publication/386115815_Reply_A_comment_on_vi...
Best regards.
I was told that the link doesnt work
That is the link https://efzu.fa.em2.oraclecloud.com/hcmUI/CandidateExperience/en/sites/C.... Or just google:
PhD scholarship – Prediction and Modelling of Damage Mechanisms of Exra-Large Wind Turbine Blades - DTU Wind
No, I didn't reply thrice.
In reply to Postdoctoral position in Mechanics of Degradable Polymers at Oxford University
No, I didn't reply thrice.
No, I didn't reply thrice.
In reply to Postdoctoral position in Mechanics of Degradable Polymers at Oxford University
No, I didn't reply thrice.
No, I didn't reply thrice.
In reply to Postdoctoral position in Mechanics of Degradable Polymers at Oxford University
No, I didn't reply thrice.
No, I didn't reply thrice.
In reply to Postdoctoral position in Mechanics of Degradable Polymers at Oxford University
No, I didn't reply thrice.
Dear young Laurence at Oxford of Ash et alia's Roger Penrose et
In reply to Postdoctoral position in Mechanics of Degradable Polymers at Oxford University
Dear young Laurence at Oxford of Ash et alia's Roger Penrose et alia,
I am too old to apply to this position.
But, as an Old Man Not at the Sea, I still do have a question for you, you the British Lady:
Would I qualify?
If yes, why?
If not, why not?
Soul-searching (don't involve those Indians attacking you; i'm not one of them) is required for this application by me to you.
Why do you get money? to ask for assistantships? Why don't I? Even if you were just like one of my students?
And, if you do accept the latter, why does Sir Roger Penrose have to get by with multiple stabs --- murder, he could not manage --- at physics, with the knife of mathematics?
Just tell me, young lady...
... Yes, I could easily have asked any young girl who sat in one of my classes (or attended one of my faculty meetings wherein I was the group leader).
... Yes, I do have an experience of teaching a class entirely consisting of just one young girl attending the class (not necessarily my class) enthusiastically, nevertheless.
Some things don't matter. Other things do. Since I noted that you do have a research budget, I thought of popping up such questions.
Don't bother.
I am at a different level. I just proved Einstein wrong. (My lone student in that class would've understood how to react, without replying this message, if my recollections are correct.)
Since you are an England-based Brit, I recommend watching this movie to you [one of your Dad/Mom's generation, in case they haven't, err, in the Western tradition, separated already]: ``Educating Rita''.
Best,
--Ajit
Dear young Laurence at Oxford of Ash et alia's Roger Penrose et
In reply to Postdoctoral position in Mechanics of Degradable Polymers at Oxford University
Dear young Laurence at Oxford of Ash et alia's Roger Penrose et alia,
I am too old to apply to this position.
But, as an Old Man Not at the Sea, I still do have a question for you, you the British Lady:
Would I qualify?
If yes, why?
If not, why not?
Soul-searching (don't involve those Indians attacking you; i'm not one of them) is required for this application by me to you.
Why do you get money? to ask for assistantships? Why don't I? Even if you were just like one of my students?
And, if you do accept the latter, why does Sir Roger Penrose have to get by with multiple stabs --- murder, he could not manage --- at physics, with the knife of mathematics?
Just tell me, young lady...
... Yes, I could easily have asked any young girl who sat in one of my classes (or attended one of my faculty meetings wherein I was the group leader).
... Yes, I do have an experience of teaching a class entirely consisting of just one young girl attending the class (not necessarily my class) enthusiastically, nevertheless.
Some things don't matter. Other things do. Since I noted that you do have a research budget, I thought of popping up such questions.
Don't bother.
I am at a different level. I just proved Einstein wrong. (My lone student in that class would've understood how to react, without replying this message, if my recollections are correct.)
Since you are an England-based Brit, I recommend watching this movie to you [one of your Dad/Mom's generation, in case they haven't, err, in the Western tradition, separated already]: ``Educating Rita''.
Best,
--Ajit
Dear young Laurence at Oxford of Ash et alia's Roger Penrose et
In reply to Postdoctoral position in Mechanics of Degradable Polymers at Oxford University
Dear young Laurence at Oxford of Ash et alia's Roger Penrose et alia,
I am too old to apply to this position.
But, as an Old Man Not at the Sea, I still do have a question for you, you the British Lady:
Would I qualify?
If yes, why?
If not, why not?
Soul-searching (don't involve those Indians attacking you; i'm not one of them) is required for this application by me to you.
Why do you get money? to ask for assistantships? Why don't I? Even if you were just like one of my students?
And, if you do accept the latter, why does Sir Roger Penrose have to get by with multiple stabs --- murder, he could not manage --- at physics, with the knife of mathematics?
Just tell me, young lady...
... Yes, I could easily have asked any young girl who sat in one of my classes (or attended one of my faculty meetings wherein I was the group leader).
... Yes, I do have an experience of teaching a class entirely consisting of just one young girl attending the class (not necessarily my class) enthusiastically, nevertheless.
Some things don't matter. Other things do. Since I noted that you do have a research budget, I thought of popping up such questions.
Don't bother.
I am at a different level. I just proved Einstein wrong. (My lone student in that class would've understood how to react, without replying this message, if my recollections are correct.)
Since you are an England-based Brit, I recommend watching this movie to you [one of your Dad/Mom's generation, in case they haven't, err, in the Western tradition, separated already]: ``Educating Rita''.
Best,
--Ajit
Dear young Laurence at Oxford of Ash et alia's Roger Penrose et
In reply to Postdoctoral position in Mechanics of Degradable Polymers at Oxford University
Dear young Laurence at Oxford of Ash et alia's Roger Penrose et alia,
I am too old to apply to this position.
But, as an Old Man Not at the Sea, I still do have a question for you, you the British Lady:
Would I qualify?
If yes, why?
If not, why not?
Soul-searching (don't involve those Indians attacking you; i'm not one of them) is required for this application by me to you.
Why do you get money? to ask for assistantships? Why don't I? Even if you were just like one of my students?
And, if you do accept the latter, why does Sir Roger Penrose have to get by with multiple stabs --- murder, he could not manage --- at physics, with the knife of mathematics?
Just tell me, young lady...
... Yes, I could easily have asked any young girl who sat in one of my classes (or attended one of my faculty meetings wherein I was the group leader).
... Yes, I do have an experience of teaching a class entirely consisting of just one young girl attending the class (not necessarily my class) enthusiastically, nevertheless.
Some things don't matter. Other things do. Since I noted that you do have a research budget, I thought of popping up such questions.
Don't bother.
I am at a different level. I just proved Einstein wrong. (My lone student in that class would've understood how to react, without replying this message, if my recollections are correct.)
Since you are an England-based Brit, I recommend watching this movie to you [one of your Dad/Mom's generation, in case they haven't, err, in the Western tradition, separated already]: ``Educating Rita''.
Best,
--Ajit
Thank you for highlighting my
In reply to Discussion of fracture paper #41 - Are dislocations good or bad guys? It depends!
Thank you for highlighting my recent paper in the official blog of ESIS and iMechanica. I also acknowledge the introduction of the stress field around an edge dislocation from the theory of elasticity.
In the paper, I treated a series of dislocation penetration at a grain boundary by MD simulation and fracture mechanics by replacing a dislocation pile-up as a mode II crack. The treatment is based on energy criteria, i.e. the energy release rate is larger than the materials resistance related to the formation energy of a step in GB at the penetration.
The theory agreed with the MD results quite well. On the other hand, some researchers treated the dislocation penetration through the dislocation bow-out mechanism from GBs, and shear stress and the distance between both ends of bow-out dislocation were used for the condition.
I have interests in the applicability of the energy criterion to other GBs and more general cases. Also, how energy and stress criteria should be treated in dislocation penetration at GBs.
Ryosuke Matsumoto
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