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B03 - Corrosion modeling for the evaluation of mechanically joined components

In modern lightweight structures, especially in hybrid construction, contact corrosion plays a significant role in evaluating the tolerable loads due to the large number of material combinations, since corrosion can significantly reduce the fatigue strength of joints.

With damage mechanics, a powerful method has developed to predict the failure of joints. Coupled simulations can replace time-consuming experimental tests in conjunction with classical fatigue strength concepts. For damage due to corrosion, only a few descriptions exist so far: these include primarily phenomenologically based approaches; furthermore, the first physically motivated models, such as those based on diffusion equations and reaction kinetics for the considered species have been investigated.
Thus, in a coupled model, the classical mechanical damage can be extended by describing the degradation of the material due to corrosion.

The aim of the present subproject is to combine a classical mechanical damage formulation with contributions from material degradation due to corrosion in order to obtain a closed model that takes into account the influences of corrosion on damage. It is important to consider a full coupling, since particle transport is faster in mechanically damaged areas. Compared to classical fatigue strength, this detailed field approach also offers the advantage that it can correctly represent local corrosion phenomena (contact corrosion) in the region between the joining partners.

The properties of the joined structure and the findings on the condition of the joint after the joining process are then incorporated into the numerical simulation. Likewise, the maximum tolerable corrosion effects based on fracture mechanical investigations must also be taken into account. Together with the experimental partners of the Transregio, model parameters can then be determined and the numerical simulation can be verified. Based on the numerical results, design recommendations - taking corrosion into account - can then be derived together with other subprojects.

Thus, through the close connection to the other projects within the Transregio, the present subproject provides (i) a coupled model for the description of the damage due to both high cyclic loading and contact corrosion, (ii) the material parameters used therein, as well as (iii) effects of the prior damage due to the joining process.

Publications


Open list in Research Information System

A First Approach for the Treatment of Galvanic Corrosion and of Load-Bearing Capacity of Clinched Joints

S. Harzheim, C. Steinfelder, T. Wallmersperger, A. Brosius, Key Engineering Materials (2021), 883, pp. 97-104

Corrosion is a major cause for the failure of metallic components in various branches of the industry. Depending on the corrosion severity, the time until failure of the component varies. On the contrary, a study has shown that certain riveted metal joints, exposed to a short period of mechanical loading and corrosion, have greater fatigue limits. This study gives rise to the question how different corrosion exposure times affect joint metallic components. In the present research, a theoretical approach is developed in order to evaluate the influence of galvanic corrosion on joint integrity of clinched metal joints. At first, the framework for modeling galvanic corrosion is introduced. Furthermore, a simulative investigation of a clinching point is carried out based on the assumption that corrosion leads to a reduction of the contact area which leads to a local increase in contact pressure. For this purpose, the stiffness values of individual elements in a finite element model are reduced locally in the contact area of the undercut and the contact stress along a path is evaluated. Summarizing, a modeling approach is introduced to investigate corrosion effects on load-bearing behavior of clinched joints.


A first Model of Fatigue Corrosion of a Metal through Hydrogen Embrittlement

M. Hofmann, Y. Shi, T. Wallmersperger, PAMM (2021), 20

Predicting the durability of components under mechanical loading combined with environmental conditions leading to corrosion is one of the most challenging tasks in mechanical engineering. Precise predictions are neccesary for lightweight design in transportation due to environmental protection. During corrosion often hydrogen is produced by electrochemical reactions. Hydrogen embrittlement is one of the most feared damage mechanisms for metal constructions leading to early and unexpected failure. Until now predictions are mostly done through costly experiments. In the present research, a first simple simulation model based on the fundamentals of electrochemistry and continuum damage mechanics is developed to couple the damage induced by the mechanical stress with the hydrogen embrittlement. Results of the durability are presented for the case of uniaxial cyclic loading for varying testing frequency.


A Review on the Modeling of the Clinching Process Chain - Part I: Design Phase

B. Schramm, S. Martin, C. Steinfelder, C.R. Bielak, A. Brosius, G. Meschut, T. Tröster, T. Wallmersperger, J. Mergheim, Journal of Advanced Joining Processes (2022), 6, 100133

DOI


A Review on the Modeling of the Clinching Process Chain - Part II: Joining Process

B. Schramm, J. Friedlein, B. Gröger, C.R. Bielak, M. Bobbert, M. Gude, G. Meschut, T. Wallmersperger, J. Mergheim, Journal of Advanced Joining Processes (2022), 100134

DOI


A Review on the Modeling of the Clinching Process Chain - Part III: Operational Phase

B. Schramm, S. Harzheim, D. Weiß, T.D. Joy, M. Hofmann, J. Mergheim, T. Wallmersperger, Journal of Advanced Joining Processes (2022), 100135

DOI


Open list in Research Information System

Contact

Prof. Dr.-Ing. habil. Thomas Wallmersperger

Transregional Collaborative Research Centre 285

subproject B03

Phone:
+49 351 463337013

Contact

Dr.-Ing. Martin Hofmann

Transregional Collaborative Research Centre 285

Teilprojekt B03

Martin Hofmann
Phone:
+49 351 463 39166

Contact

Dipl.-Ing. Sven Harzheim

Transregional Collaborative Research Centre 285

Teilprojekt B03

Sven Harzheim
Phone:
+49 351 46333401