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fatigue sizing

  • Thread starter Thread starter mitnick
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mitnick

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Hello everyone,
I have to design a mat that supports a weight of 2 tons and is characterized by a pantograph model. the height that will have to reach the structure is pairs to 2 meters while the size of the floor will be 2500x1250 mm. how do I make the dimensioning to fatigue of the parts?
 
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I think this is the way, at least I would do this:
- "resolve" the pantograph with all the forces at stake depending on the load to be lifted
- calculations all stresses on the various parts (pantograph, hinges etc.)
- make a static pre-dimensionalization and deformation of the parts (not everything will be fatigued) combining various stresses for example with von mises
- define the various geometries (cuts, gorge holes etc.) in the zones subject to various loads and calculate the various coefficients k (internal and external parameters) and revenues the correct fatigue curve for your material (remember that fatigue is a local phenomenon and therefore you have to check locally to be safe).
- check welds (following the uni-cnr10011 or eurocode3).
- check if there are particular requirements to be met for application regulations
This is what I would do, I hope I've been useful to you
Hi.
 
Well, to the eye surely pins and rods must be dimensional to fatigue. ..consider that when you pull on a load you might experience fluctuations...to explain if the system is not very rigid you have "spring" behaviors of the pantograph structure...I still believe that there is a specific rule for these lifters. . .
 
mitnick said:
Hello everyone,
I have to design a mat that supports a weight of 2 tons and is characterized by a pantograph model. the height that will have to reach the structure is pairs to 2 meters while the size of the floor will be 2500x1250 mm. how do I make the dimensioning to fatigue of the parts?
Click to expand...
Why did you start a further discussion on the same topic? ?
You had to keep going.
now you create casinos and "dispersion".

greetings
Mar
 
Marco excuse but this discussion only refers to the size of the structure.
how do I share the 2 tons of load on the frame of the upper floor? and then on the supports that lift the floor?
 
mitnick said:
Marco excuse but this discussion only refers to the size of the structure.
Click to expand...
according to your reasoning soon you will feel authorized to open another regarding the color of the paint to give to your fork? :biggrin:

greetings
Mar
 
mitnick said:
...
how do I share the 2 tons of load on the frame of the upper floor? and then on the supports that lift the floor?
Click to expand...
..and in the meantime you keep not going to see the other similar "old" debate.
This part you requested had already been resolved.

greetings
Marco:smile:
 
I was probably not clear in my questions :tongue:
what are the mathematical steps for the sizing and relative fatigue verification of the structure? Do I share my 203n for the number of supports? I remember that for the sizing of the trees I was going to define an admissible sigma to compare then with the ideal one but in this case I do not have trees but profiles, you would know better how to operate? the first problem concerns the choice of tubulars that constitute the platform and subsequently the analysis of the 4 supports that lift the latter. what are the steps to follow and what laws to use?
 
mitnick said:
I was probably not clear in my questions :tongue:
what are the mathematical steps for the sizing and relative fatigue verification of the structure? Do I share my 203n for the number of supports? I remember that for the sizing of the trees I was going to define an admissible sigma to compare then with the ideal one but in this case I do not have trees but profiles, you would know better how to operate? the first problem concerns the choice of tubulars that constitute the platform and subsequently the analysis of the 4 supports that lift the latter. what are the steps to follow and what laws to use?
Click to expand...
Hi, mitnick.
as they have already answered you, the procedure is the one indicated by maca.

for "the calculations" you must schematize the structure, place the internal and external constraints of the structure and solve. once you determine the binding reactions you will pass to the analysis of internal actions, static verification, fatigue verification and maybe even a fem at least to verify if you have made mistakes in the calculation by hand.

a good book of construction science, a manual of mechanics, eurocode 3 and uni 10011 (for bolting, welding and steel structures)
 
My problem is not to remember the formulation necessary for static and fatigue verification, I can get it back!
 
the uni 7670 is a standard for the design of lifting equipment and reports a long chapter dedicated to fatigue dimensionalization
 
meccanicamg said:
that however was withdrawn on 2009-01-22 without replacement.
Click to expand...
Yes, but the concepts that you report remain valid.
it has been withdrawn without replacement, since all norms on the design of the cranes had to refer to an en harmonised Eurocode style, which unfortunately for her and for the builders (and fortunately for the users) has been put out law as it did not respect the res of the machine directive, in particular, look at case, the resistance to fatigue (there was a recommendation of the community on this matter, received in Italy by a ministerial decree: just recovery).
Hi.
 

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