First, I pondered about the concepts of force and pressure, force cant exist without pressure, vice versa. Imagine a an adhesive sandwiched between a tabletop and a silicon wafer. (this is part 1) Now, when you exert a shearing force Fshear above the adhesive and between the silicon thickness, the adhesive-silicon force exerts an adhesive force opposite in direction to the shearing force. Simultaneously, the adhesive-table force exerts an adhesive force opposite in direction to the shearing force. This is shown as in diagram 1. At the point of cohesive failure, Fshear = F'si + F'table If F'si > F'table, the point of rupture would be the table-adhesive contact If F'table > F'si, the point of rupture would be the silicon-adhesive contact. Now, I know that F'table is less than Ftable, where Ftable is the TRUE or MAXIMUM adhesive contact force between the adhesive and table. Furthermore, I know that F'si is less than Fsi, where Fsi is the TRUE of MAXIMUM adhesive contact force between the adhesive and silicon.