玻 璃 微 流 控 芯 片 模 压 成 形 裂 纹 形 成 与 抑 制

To address the thermal cracking and fracture that readily occur in the deep-cavity/shallow-groove transition region during the precision molding of stepped optical glass microfluidic chips, the mechanism of microcrack formation was investigated and a crack-suppression method was proposed. The cooling and annealing process three-dimensional thermo-mechanical coupled finite element model was established based on the high-temperature viscoelastic constitutive behavior of D-ZK2N glass. The Deborah number was introduced to characterize the competition between structural relaxation and stress freezing, and a gradient cooling strategy was developed and verified through molding experiments. The results show that non-uniform thermal inertia and volumetric shrinkage mismatch are the main causes of the“compressive outside-tensile inside”stress concentration in the transition region. Under linear cooling, stress in this region continuously accumulated and eventually formed a high risk of cracking. After adopting the gradient cooling strategy, structural relaxation in the transition region was enhanced, and simulation results showed the residual stress in the transition region decreased by 22. 4%. No cracks were observed in the molded part, and the molded depth of the deep-cavity structure reached 4. 522 mm. These results indicate that the Deborah-number-based gradient cooling strategy can effectively suppress thermal cracking in stepped transition regions and is suitable for the precisionmolding of glass microfluidic chips with large aspect-ratio structures.