The peeling behavior of a heterogeneous elastic film on a rigid substrate

Although the interfacial peeling behavior of a homogeneous film-substrate system is well understood, the peeling process of a heterogeneous elastic film bonded to a rigid substrate is still unclear. In the present paper, the peeling behavior of a heterogeneous film adhering on a rigid substrate under a vertical peeling force is investigated theoretically, in which the film's heterogeneity is characterized by the change of bending stiffness along the length of the film. Based on the principle of minimum potential energy, the typical relationship between the peeling force and the peeling displacement during the whole peeling process is achieved. Different from the homogeneous film case, the peeling force can be regulated dramatically by the film's heterogeneous bending stiffness during the peeling process. When the interfacial debonding front propagates from a compliant segment to a stiff segment, the peeling force is enhanced; while the peeling force is weakened as the interfacial debonding front goes from a stiff segment to a compliant one. The enhancement or weakening of the peeling force depends not only on the bending stiffness of each segment of the film but also on the bending stiffness ratio of neighboring segments, as well as the adhesion length of each segment and the interfacial adhesion properties. The mechanism underlying the heterogeneity-induced tunable peeling force is further elucidated by the change rate of elastic bending energy stored in the film and energy overcoming the interfacial interaction potential during the peeling process. The transfer and redistribution of the elastic bending energy are the main factors that induce the change of peeling force as the interfacial debonding front reaches the boundary of neighboring segments with different bending stiffness. The results of this paper can provide a new strategy for designing film-substrate systems with adjustable adhesion without changing the interfacial characteristics.