On the effect of microscopic surface roughness on macroscopic polymer-metal adhesion

Surface roughening is a generally accepted way to enhance adhesion between two dissimilar materials. One of the key mechanisms, besides the obvious increase in surface area, is the transition from adhesive to cohesive failure, i.e., crack kinking. This chapter presents several analysis methods to study this phenomenon. First, a semi-analytical approach is discussed in which the competition between adhesive and cohesive cracking is analyzed by means of the theoretical relation between interface and kinking stress intensity factors. Accordingly, the crack kinking location and kinking angle are readily calculated. Second, transient crack propagation simulations are performed to calculate crack paths at a roughened surface by means of cohesive zone elements. Third, delamination experiments are performed on samples containing well-controlled surface roughness profiles