Modeling and Simulation of Curing Kinetics and Stress of a Bonded Mirror with a Room-Temperature Curable Adhesive

Adhesive bonding widely appears in optomechanical products. Nevertheless, the occurrence of curing stress often leads to structure deformation, which significantly compromises the performance of optomechanical systems. This work focuses on the formation and evolution of curing stress and its influence on a multi-point face-bonded mirror. The adhesive's degree of cure (DOC) was measured using the differential scanning calorimetry (DSC) technique. The functional relationship between DOC and glass-transition temperature (T_g) was determined utilizing DiBenedetto's equation. The time-DOC shift factor of the adhesive was obtained by stress relaxation tests on specimens with different DOCs. Subsequently, a viscoelastic constitutive model concerning the curing process and an accurate finite-element (FE) model of the bonded mirror were developed to simulate the surface-figure error (SFE) evolution. The predicted surface figure was compared with experiments, and the model was verified and validated. Further, simulation analyses were conducted on the performance of the multi-point face-bonded mirror, and the influences of adhesive thickness, bonding area, and spot number on the SFE of the mirror were examined.