טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentLeonid Chernin
SubjectDelamination Buckling of a Beam Attached to a Rigid
Substrate
DepartmentDepartment of Civil and Environmental Engineering
Supervisor Professor Volokh Konstantin


Abstract

The aim of this paper is to study the stability behaviour of the one-dimensional film/substrate system subjected to a range of thermal loads. The analysis method includes the effect of a finite, non-zero interfacial compliance. This complaint interface between a film and a substrate is considered by introducing the cohesive surface criterion. The film is considered as a Timoshenko beam. The cohesive layer of zero thickness is described by normal and tangential tractions and corresponding displacement jumps across the compliant interface. An exponential constitutive law relating tractions and displacements is considered for the cohesive surface. This problem formulation allows studying nucleation, propagation and arrest of local delamination: edge cracks and blisters. Finite element analysis is carried out for qualitative study of the influence of different parameters of the thin film and cohesive layer as well as different loads on the delamination behaviour of the film-substrate model. The results of analysis show that the stable or the unstable type of delamination propagation depends mainly on the shape of the thermal load and less on the distribution of the cohesive surface strength along the film. The location of the film separation nucleation is essentially sensitive to combination of the cohesion properties of the film/substrate interface and the thermal load shape and fewer to the film geometrical defects. It is summarized that only for special cases of the film and cohesion property combinations the inside blisters are created, otherwise the unstable inside delamination cases or edge cracks take place. The material imperfection of the film is not crucial for the delamination behaviour.