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Damage assessment of threaded connections based on an advanced material model and local concepts

Panic, Darko and Beier, Heinz Thomas and Vormwald, Michael (2014):
Damage assessment of threaded connections based on an advanced material model and local concepts.
In: Procedia Engineering, Elsevier, pp. 119-128, 74, ISSN 18777058, [Online-Edition: http://www.sciencedirect.com/science/article/pii/S1877705814...],
[Article]

Abstract

In the actual guidelines, for example the German VDI guideline 2230 [1] or the EUROCODE 3 [2], the fatigue assessment of bolted connections and bolts is based on the nominal stress approach. The FKM guideline for analytical strength assessment [3] does not include concepts for a threaded connection, it refers to the existing guidelines as [1]. At present there does not exist any guideline, which provides a damage assessment for general threaded connection by applying local concepts. In the present paper the basics of such a concept are outlined. The investigated metal is 34CrNiMo6, which is generally used for screw threads. The experimental determination of the local stress-strain behaviour in mechanically threaded connections is practically not feasible and needs a numerical approach. This numerical attempt consists of two main tasks, namely the description of the material properties and finite element (FE) analysis. The first one is concerned with the identification of material parameters, which are necessary for the FE analysis, especially for the advanced material model. The experimental work is given by determining the initial monotonic stressstrain curve, the initial unloading curve, the cyclic stress relaxation and cyclic creep. The parameter identification is accomplished using the software MATLAB, which includes the essential nonlinear optimization algorithms. The obtained parameters are entered in the FE software, which is used for the further FE analysis. The distinctive features of the FE analysis are the nonlinearity, especially nonlinear material behaviour, nonlinear contact algorithms and the consideration of large deformations, the high number of load steps and the various load ratio values (R = 0.06 and R = 0.71). The results of the FE analysis are used for the assessment of threaded connections. The damage assessment is realized with the local strain approach based on the damage parameters PSWT and PJ. Finally the result of the simplified method according to Schneider is applied on a high preloaded bolt connection (R = 0.71) and compared with the result achieved with the advanced material model. © 2014 The Authors. Published by Elsevier Ltd. Selection and peer-review under responsibility of the Politecnico di Milano, Dipartimento di Meccanica.

Item Type: Article
Erschienen: 2014
Creators: Panic, Darko and Beier, Heinz Thomas and Vormwald, Michael
Title: Damage assessment of threaded connections based on an advanced material model and local concepts
Language: English
Abstract:

In the actual guidelines, for example the German VDI guideline 2230 [1] or the EUROCODE 3 [2], the fatigue assessment of bolted connections and bolts is based on the nominal stress approach. The FKM guideline for analytical strength assessment [3] does not include concepts for a threaded connection, it refers to the existing guidelines as [1]. At present there does not exist any guideline, which provides a damage assessment for general threaded connection by applying local concepts. In the present paper the basics of such a concept are outlined. The investigated metal is 34CrNiMo6, which is generally used for screw threads. The experimental determination of the local stress-strain behaviour in mechanically threaded connections is practically not feasible and needs a numerical approach. This numerical attempt consists of two main tasks, namely the description of the material properties and finite element (FE) analysis. The first one is concerned with the identification of material parameters, which are necessary for the FE analysis, especially for the advanced material model. The experimental work is given by determining the initial monotonic stressstrain curve, the initial unloading curve, the cyclic stress relaxation and cyclic creep. The parameter identification is accomplished using the software MATLAB, which includes the essential nonlinear optimization algorithms. The obtained parameters are entered in the FE software, which is used for the further FE analysis. The distinctive features of the FE analysis are the nonlinearity, especially nonlinear material behaviour, nonlinear contact algorithms and the consideration of large deformations, the high number of load steps and the various load ratio values (R = 0.06 and R = 0.71). The results of the FE analysis are used for the assessment of threaded connections. The damage assessment is realized with the local strain approach based on the damage parameters PSWT and PJ. Finally the result of the simplified method according to Schneider is applied on a high preloaded bolt connection (R = 0.71) and compared with the result achieved with the advanced material model. © 2014 The Authors. Published by Elsevier Ltd. Selection and peer-review under responsibility of the Politecnico di Milano, Dipartimento di Meccanica.

Journal or Publication Title: Procedia Engineering
Volume: 74
Publisher: Elsevier
Divisions: 13 Department of Civil and Environmental Engineering Sciences > Institute of Steel Constructions and Material Mechanics > Fachgebiet Werkstoffmechanik
13 Department of Civil and Environmental Engineering Sciences > Institute of Steel Constructions and Material Mechanics
13 Department of Civil and Environmental Engineering Sciences
Date Deposited: 27 Jan 2015 14:03
Official URL: http://www.sciencedirect.com/science/article/pii/S1877705814...
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