Determination of Local Stresses and Strains within the Notch Strain Approach: Efficient Implementation of Notch Root Approximations

An estimation of the elastic-plastic stress state using elasticity-theoretical input data is an essential part of the service life estimation with the local strain approach in general and a German guideline based on it, in particular. This guideline uses two different notch root approximations (an e...

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Autores principales: Ralf Burghardt, Lukas Masendorf, Michael Wächter, Alfons Esderts
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Publicado: MDPI AG 2021
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spelling oai:doaj.org-article:3db04c40d8134e90b6c17079626acaa32021-11-11T15:21:49ZDetermination of Local Stresses and Strains within the Notch Strain Approach: Efficient Implementation of Notch Root Approximations10.3390/app1121103392076-3417https://doaj.org/article/3db04c40d8134e90b6c17079626acaa32021-11-01T00:00:00Zhttps://www.mdpi.com/2076-3417/11/21/10339https://doaj.org/toc/2076-3417An estimation of the elastic-plastic stress state using elasticity-theoretical input data is an essential part of the service life estimation with the local strain approach in general and a German guideline based on it, in particular. This guideline uses two different notch root approximations (an extended version of Neuber’s rule and an approach according to Seeger and Beste) for this estimation. Both require the implementation of Newton’s method to be iteratively solved. However, many options are left open to the user concerning implementation in program code. This paper discusses ways in which notch root approximation methods can be implemented efficiently for use in software systems and elaborates an application recommendation. The following aspects and their influence on the computational accuracy and performance of Newton’s method are considered in detail: influence of the formulation of the root finding problem, determination of the derivative required for Newton’s method and influence of the termination criterion. The investigation shows that the advice given in the abovementioned guideline indeed leads to a conservative implementation. By carefully considering the investigated aspects, however, the computational performance can be increased by approximately a factor of 2–3 without influencing the accuracy of the service life estimation.Ralf BurghardtLukas MasendorfMichael WächterAlfons EsdertsMDPI AGarticleNeuber’s rulefatigue life calculationnotch strainsnotch stressesfatigue of materialslocal strain approachTechnologyTEngineering (General). Civil engineering (General)TA1-2040Biology (General)QH301-705.5PhysicsQC1-999ChemistryQD1-999ENApplied Sciences, Vol 11, Iss 10339, p 10339 (2021)
institution DOAJ
collection DOAJ
language EN
topic Neuber’s rule
fatigue life calculation
notch strains
notch stresses
fatigue of materials
local strain approach
Technology
T
Engineering (General). Civil engineering (General)
TA1-2040
Biology (General)
QH301-705.5
Physics
QC1-999
Chemistry
QD1-999
spellingShingle Neuber’s rule
fatigue life calculation
notch strains
notch stresses
fatigue of materials
local strain approach
Technology
T
Engineering (General). Civil engineering (General)
TA1-2040
Biology (General)
QH301-705.5
Physics
QC1-999
Chemistry
QD1-999
Ralf Burghardt
Lukas Masendorf
Michael Wächter
Alfons Esderts
Determination of Local Stresses and Strains within the Notch Strain Approach: Efficient Implementation of Notch Root Approximations
description An estimation of the elastic-plastic stress state using elasticity-theoretical input data is an essential part of the service life estimation with the local strain approach in general and a German guideline based on it, in particular. This guideline uses two different notch root approximations (an extended version of Neuber’s rule and an approach according to Seeger and Beste) for this estimation. Both require the implementation of Newton’s method to be iteratively solved. However, many options are left open to the user concerning implementation in program code. This paper discusses ways in which notch root approximation methods can be implemented efficiently for use in software systems and elaborates an application recommendation. The following aspects and their influence on the computational accuracy and performance of Newton’s method are considered in detail: influence of the formulation of the root finding problem, determination of the derivative required for Newton’s method and influence of the termination criterion. The investigation shows that the advice given in the abovementioned guideline indeed leads to a conservative implementation. By carefully considering the investigated aspects, however, the computational performance can be increased by approximately a factor of 2–3 without influencing the accuracy of the service life estimation.
format article
author Ralf Burghardt
Lukas Masendorf
Michael Wächter
Alfons Esderts
author_facet Ralf Burghardt
Lukas Masendorf
Michael Wächter
Alfons Esderts
author_sort Ralf Burghardt
title Determination of Local Stresses and Strains within the Notch Strain Approach: Efficient Implementation of Notch Root Approximations
title_short Determination of Local Stresses and Strains within the Notch Strain Approach: Efficient Implementation of Notch Root Approximations
title_full Determination of Local Stresses and Strains within the Notch Strain Approach: Efficient Implementation of Notch Root Approximations
title_fullStr Determination of Local Stresses and Strains within the Notch Strain Approach: Efficient Implementation of Notch Root Approximations
title_full_unstemmed Determination of Local Stresses and Strains within the Notch Strain Approach: Efficient Implementation of Notch Root Approximations
title_sort determination of local stresses and strains within the notch strain approach: efficient implementation of notch root approximations
publisher MDPI AG
publishDate 2021
url https://doaj.org/article/3db04c40d8134e90b6c17079626acaa3
work_keys_str_mv AT ralfburghardt determinationoflocalstressesandstrainswithinthenotchstrainapproachefficientimplementationofnotchrootapproximations
AT lukasmasendorf determinationoflocalstressesandstrainswithinthenotchstrainapproachefficientimplementationofnotchrootapproximations
AT michaelwachter determinationoflocalstressesandstrainswithinthenotchstrainapproachefficientimplementationofnotchrootapproximations
AT alfonsesderts determinationoflocalstressesandstrainswithinthenotchstrainapproachefficientimplementationofnotchrootapproximations
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