The S/N fatigue curves for the welded joints are determined by the HAZ residual stress level and sign. Also it is a structurally sensitive characteristic depending on the stress concentration. So I believe fatigue test results would hardly correlate with tensile or hardness test results.

thank you sergei tarasov, I was hoping to get a relationship equation.

There is a relationship proposed by Manson in which low cycle fatigue properties can be predicted (book by G.E. DIETER- Chapter on fatigue of metals) using tensile properties. The relationship uses the following tensile properties: Young's modulus, UTS and tensile fracture strain.

I like to add on to Dr. Sergei Tarasov and Dr. Sunil Goyal. I have come across a few references (but I have not worked on fatigue behavior) that express the correlation between fatigue strength and other mechanical properties such as tensile strength, hardness. But I do  not know how far these relationships are valid for high strength materials and also for welds. Please see the papers below: may be useful.

1) "General relation between tensile strength and fatigue strength of metallic materials", J.C. Pang, S.X.Li, Z.G.Wang, Z.F.Zhang, Materials Science & Engineering A 564 (2013) 331-341.

2) "Relations between fatigue strength and other mechanical properties of metallic materials", J. C. PANG, S. X. LI, Z. G. WANG and Z. F. ZHANG, Fatigue & Fracture of Engineering Materials & Structures (FFEMS) , Volume 37, Issue 9, 2014, pp. 958-976 (Wiley Publishing Ltd).

Also, please look in to: 3) "Fatigue Data Book: Light Structural Alloys", By ASM International, 1995. 

Since the fatigue strength in the as-welded condition is not dependent on the yield- and/or tensile- strength of parent plate I assume the question relates to parent plate strength.

For a relation of fatigue strength vs UTS you can read my research on the subject in the page 11 in the following link:

http://lets-global.com/doc/Fatigue_Behaviour-_of-_Welded-_High_Strength_Steels.pdf

This work includes steel up to 560HB hardness and it would give you a good understanding of my work on the subject. I hope it is of use for your research.

It is extremely different character mechanical properties, it caused you have to use dynamic load for fatigue test and static load for the other mechanical test. I suggest you to do the test by using standard machine.

Dear Uzor Steve Emezuru,

please, look in RG the recently given answers to a question of Braj Krishna 

from Motilal Nehru National Institute of Technology:

"Can we find the fatigue life of materials without performed the test on the basis of young's modulus, yield and ultimate strength? Is it possible theoretical evaluation of fatigue life on the basis of mechanical properties of material?

May be, you will find some useful information.

Serge 

Among these relations, the general relation between fatigue strength σw and tensile strength σb, σw = σb(C − P ⋅ σb), where C and P are parameters, (hereafter, the general fatigue formula) can well predict the fatigue strength with increasing the tensile strength in a wide range for many materials such as conventional metallic materials, newly developed materials and engineering components.

Uzor Steve Emezuru Sunil Goyal Is there any relationship between number of cycles "N"and Material's yield strength degradation?

@ Uzor Steve Emezuru Sunil Goyal :

It's tough to find a generic relationship since some materials cyclic soften and some cyclic harden.

Also, once you get out to the vicinity of >=80% of life, crack propagation in strain cycled smooth specimens will look like cyclic softening.

Michael Henry I have experimental fatigue test data (linear compression)of a polymer material "PLA"

Number of cycle = 500 (Materiel not failed)

Stress Ratio > 0

in all cycles Min and Max stress values not same

how can i find fatigue life of this ?

any statistical approach that first filter the data and then predict fatigue life?

i attached an excel file please see column A, B, C for real data

@ Asad Maqsood

I'm looking at your data file and have several questions.

Should we take the detailed discussion off of Research Gate?

If you'd like to, post your email, and I'll email you.

Michael Henry sure

[email protected]

Dear Uzor certainly there is a relationship and UTS is useful in calculations

Fatigue Life of the material depends on the yield strength (For ductile material).

In my experience, fatigue limits of steels are proportional to their yield strengths and hardness for smooth specimens. However, for weldments, fatigue limits mainly depend upon the stress and strain concentration factors and have great scatters. Some examples:

Article Fatigue strength distribution and probabilistic evaluation o...

Article Mean and residual stress effects on fatigue behavior in a pr...

Fatigue is far too complex for these simple relationships.

If you're going to suggest one, that you have to also define the applicable conditions.

• material class
• stress or strain cycling
• temperature
• frequency
• waveform
• environment
• microstructure
• etc.
• etc.

Most of the ones proposed here may only apply to time independent fatigue in relatively fine grain, relatively homogeneous, polycrystalline materials.

Classically you can find lots of correlations over a narrow range of variables. If that's the case you're interested in, that's okay.

Some attempts were made to find this promising correlations. The good perspectives are in failure mechanics, taking into account the single static tension test of specimen with initial artificial crack of regulated form. The measuring of crack propagation in time give us valuable information which interpreted by special calculations.

It is true that fatigue behavior is complex and could not be precisely expressed by a simple equation. Meanwhile, giving some relationships under a certain condition are interesting. Additionally, 'proportional relationship' disappears when the fatigue strength approaches 1500 MPa in high strength steels as shown in a reference:

Article A practical model for efficient anti-fatigue design and sele...

Correction: 'when the tensile strength approaches 1500 MPa'

Fatigue properties are very difficult to predict as it is influenced by many external factors like surface roughness, grain size, size etc and even the temperature at which the test is carried out. Soderbergh and Goodman relationship are often used to relate fatigue life with yield or ultimate strength of material, but none are consistent.

SWT relation and Y-T-F model are interesting, and they have been discussed in the above recommended references.

For a first cut estimate of the fatigue strength of steel (not welded), see

https://www.timkensteel.com/~/media/Practical-Data-For-Metallurgists-TimkenSteel_20170126.ashx#Relationship-of-Fatigue-Strength-to-Tensile-Strength .

Dear Uzor Steve Emezuru,

Fatigue with tensile stress

There is a direct correlation between tensile strength and fatigue strength; higher-tensile-strength steels have higher endurance limits. The endurance limit is normally in the range of 0.35 to 0.60 of the tensile strength.The general relation between fatigue strength σw and tensile strength σb, σw = σb(C − P ⋅ σb), where C and P are parameters, (hereafter, the general fatigue formula) can well predict the fatigue strength with increasing the tensile strength in a wide range for many materials such as conventional metallic materials, newly developed materials and engineering components.

Fatigue with yield stress

Fatiguecracking normally results from cyclic stresses that are well belowthe static yield strength of the material. (In low-cycle fatigue, however, or if the material has an appreciable work-hardening rate, the stressesalso may be above the static yield strength).

Fatigue with hardness

Relationship of Brinell hardness and fatigue strength coefficient increases almost linearly. The fatigue strength confident has a fine linear relationship with Brinell hardness.

Fatigue with impact toughness

The relation between fatigue strength and impact toughness of AISI 4340 steel and copper beryllium alloy and found that there is no obvious relation. For example, copper beryllium alloy, the relations between fatigue ratio and impact toughness as well as between fatigue strength and impact toughness of copper beryllium alloy are not linear and quadratic, which only confirms that the high or low impact toughness cannot lead to the highest fatigue strength.

Ashish

when we are saying test is different from property .property is the thing we find from the test ,Tensile test shows stress and strain of material when push the material in standard order you can find the order from ASTM search it on net google or other sites with keyword how I can set tensile test with ASTM orders .this test shows material behavior to say it with easy English I will say short time shape chaining that means after we on load it shape is back no change long time shape chapping is other thing this time shape changes at all from yield point to UTS point we have just change in shape with volume same but after that to fracture point or the point that martial is departed all parts can change but not in order to be used in industry for forming , but fatigue test is in different order and others too .your question was not clear to me what part do you want to find I mean relationship ? google all keywords you typed here in different windows you see what they mean look at them think and find your answer I do the same

at all . wish you like

I think the following article is appropriate to answer your question:

Article General relation between tensile strength and fatigue streng...

Good luck