Stress singularity at a sharp edge in contact problems with friction

The paper discusses the nature of the singularity that arises at a sharp edge in contact problems with friction. The theoretical treatment is based on the Mellin transform of the elastic fields. The results regarding the power singularities confirm the previous work of Gdoutos and Theocaris, but it is shown that logarithmic singularities are always present. Some experimental observations in photoelasticity are also presented. Die Art der Spannungssingularität, die an einer scharfen Ecke in Berührungsproblemen erscheint, ist für den Fall mit Reibung untersucht. Die theoretische Behandlung stützt sich auf die Mellin-Transformation der elastischen Felder. Die Ergebnisse bezüglich der Potenzsingularitäten bestätigen die früheren Resultate von Gdoutos und Theocaris. Es wird jedoch gezeigt, daß logarithmische Singularitäten stets anwesend sind. Auch einige Beobachtungen von photoelastischen Versuchen sind dargestellt.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43357/1/33_2005_Article_BF01594906.pd

Bauschinger effect in thin metal films on compliant substrates

Flexible electronic devices such as flexible displays and solar cells draw more and more attention from the industry. In these devices, the functionality is delivered by small-scale structures consisting of thin metal lines and other materials that are integrated on a compliant (e.g. polymer) substrate to make the device flexible. A major concern is reliability, since the small-scale structures with features on the order of micrometers or below are highly fragile, however, they are subjected to large thermo-mechanical loads during manufacturing and use. Although a growing literature exists on rupture and buckling of thin metal films on polymer substrates, see for instance [1], many mechanical issues of flexible electronics have not been studied in depth. In this project, one such issue, the Bauschinger effect of thin metal films bonded to a compliant substrate, will be studied in more detail, because the Bauschinger effect appears to be a particularly important issue in flexible electronics applications where the device is subjected to multiple strain cycles

A new cohesive zone model for mixed-mode decohesion

This paper focuses on the frequently adopted exponential cohesive zone law of Xu and Needleman (Xu and Needleman [1]). In spite of its wide applicability, this cohesive zone law gives an unrealistic physical response under most mixed-mode loading conditions. This conclusion is based on investigations of the influence of the coupling parameters and the assessment of the dissipated energy under mixed-mode loading conditions