low fatigue welding n cycles

[iceeyes]

Hello, for the construction project of machines I find myself to dimensional a structure that works in marine environment (it is immersed and made emerge for operations of varo and alaggio of boats).
having to ensure the exercise of the machine for 10 years, I have a number of life cycles that does not exceed 10^5 cycles.
for fatigue testing of welding are there particular regulations for low cycle numbers?
on the one cnr 10100 and on the eurocode3 I found indications only for the fatigue at high number of cycles.
if the theory does not deceive me, is it not the case to calculate the delta k and compare it with the delta k of threshold in order to avoid the nucleation of the clique? being a corrosive environment the phenomenon should be particularly aggressive.
the material with which I intend to realize the structure is s275jr, providing then cathodic protection to current taxes.

Thank you for clarification and straight

 

[Counterblow Hammer]

You need American law. . look in your library if you find "design and construction of machines" of the shigley: there should be something.. .

 

[iceeyes]

You need American law. . look in your library if you find "design and construction of machines" of the shigley: there should be something.. .

Thank you for the directions. If by shigley you mean the volume published of mcgraw hill, I will look better because I own it but I have found nothing about it.
the American regulations that interest me, correspond to the aws: american welding society?

 

[Counterblow Hammer]

I go to memory at the moment: in the shigley you will find the fatigue design section according to the American standard (in deformation control that is the one that is good for fatigue at low number of cycles); under the welding section there should be the application of this method to the fatigue sizing of welding. I hope I'm not wrong. . :

However the book is the one published by the mcgraw hill..

 

[iceeyes]

I go to memory at the moment: in the shigley you will find the fatigue design section according to the American standard (in deformation control that is the one that is good for fatigue at low number of cycles); under the welding section there should be the application of this method to the fatigue sizing of welding. I hope I'm not wrong. . :

However the book is the one published by the mcgraw hill..

aisc and aws. You're right. I'll see to them. as you say in the signature "Search... find".

problem solved. (except in the library)

Thank you counterblow hammer.

 

[Counterblow Hammer]

of nothing.. .

Good job! .

 

[meccanicamg]

on the shigley in English there is the explanation of the construction of the wohler diagram. there are all parameters to create the curve of the real piece. you have load parameter (flassection, axial or torsion), dimensional, surface finish, temperature, reliability, coatings or saline environments. knowing the stress you will get a number of cycles that will make your piece. with what should last and from there you see everything

 

[iceeyes]

also on Italian as well as on juvinall. However goodman diagram for oligocyclic fatigue can't I use it or am I wrong? because in reality the origin of doubt is due to the following fact.
in the specific technique I have to guarantee 10000 cycles and I was told to concentrate the fatigue verification only on welds and bolted connections. Being oligocyclic fatigue I can't use the goodman but mechanical fracture diagram to ensure my deltak is lower than the threshold deltak.
to which the problem becomes to find the necessary parameters considering corrosive environment.

 

[meccanicamg]

can also be as you say though if you have oligocyclical fatigue with low number of cycles (10000) you are between 1000 and 1000000 i.e. in the descending section of the curve of the more which is clearly defined and with r=1 i.e. sigma media = 0 It's perfect.
large diatriba: if use Other I am tall with sigma, if I use googman low linear. the threshold deltak uses it to check but if you have to create a chart, analyze, hypothesize, etc. (so you are on the side of the reason with the due coefficient cautele) what do you use? .
If you look uni en 1993-1-8 e uni en 1993-1-9 there is the explanation of how to make fatigue checks of welds and reports more methods of verification that are corrected with coefficients depending on whether welding is vital, controllable, etc. also indicates curve sn with coefficients m = 3 ed m = 5, so it means that you can use the miner method, the delta verification method but all this is marked on the diagram more.I remember two things:
1) depends on the professor how and what he teaches, depends on the books, depends on the laboratory experiences, depends on what polytechnic you are (it is a life that for the structural things polymi and polite they say different in many things) and fortunately the regulations dictate law
2) the non-theoretical wohler curve but the correct one keeps in mind, as I told you in the other post of all factors related to load, temperature, coating (zinc, metallic paint, anodization etc), environmental factors and more. there is the formulation of the curve to low cycles of fatigue up to 1000 and that beyond 1000 until infinite and has been clearly formulated with equations. the theoretical coefficient used for the definition of curves in turn is correct according to the breaking load of the material and the fatigue ratio and other things. clearly the regulations do not cover all coefficients because it is expressed that the thing is of experimental deduction and despite we are in 2013 the phenomenon of fatigue is still a great stranger.

 

[Marcos555]

I used two books to polytechnic juvinall, and "machine construction project", the latter for me is the best. the chapter begins on page 227, there are many examples and exercises done clear and well commented. for example someone interesting with the combination of multiple load modes.
http://www.catalogo.mcgraw-hill.it/catlibro.asp?item_id=2407

 

[iceeyes]

can also be as you say though if you have oligocyclical fatigue with low number of cycles (10000) you are between 1000 and 1000000 i.e. in the descending section of the curve of the more which is clearly defined and with r=1 i.e. sigma media = 0 It's perfect.
large diatriba: if use Other I am tall with sigma, if I use googman low linear. the threshold deltak uses it to check but if you have to create a chart, analyze, hypothesize, etc. (so you are on the side of the reason with the due coefficient cautele) what do you use? .
If you look uni en 1993-1-8 e uni en 1993-1-9 there is the explanation of how to make fatigue checks of welds and reports more methods of verification that are corrected with coefficients depending on whether welding is vital, controllable, etc. also indicates curve sn with coefficients m = 3 ed m = 5, so it means that you can use the miner method, the delta verification method but all this is marked on the diagram more.I remember two things:
1) depends on the professor how and what he teaches, depends on the books, depends on the laboratory experiences, depends on what polytechnic you are (it is a life that for the structural things polymi and polite they say different in many things) and fortunately the regulations dictate law
2) the non-theoretical wohler curve but the correct one keeps in mind, as I told you in the other post of all factors related to load, temperature, coating (zinc, metallic paint, anodization etc), environmental factors and more. there is the formulation of the curve to low cycles of fatigue up to 1000 and that beyond 1000 until infinite and has been clearly formulated with equations. the theoretical coefficient used for the definition of curves in turn is correct according to the breaking load of the material and the fatigue ratio and other things. clearly the regulations do not cover all coefficients because it is expressed that the thing is of experimental deduction and despite we are in 2013 the phenomenon of fatigue is still a great stranger.

Thanks for the exhaustive answer. the problem was born precisely from the fact that on books and in class we always talk about high number of cycles while scarce examples of sizing on the low number of cycles. the professor in question suggested not to make fatigue checks of the whole structure but only of these joints (bulbs and welds) but on the threshold deltak and welds, I have not found norms. I will now look at the regulations you have indicated to me and I think I will use palmgreen-miner on the wohler diagram.