Vibration pretreatment microwave curing is a high-quality and efficient composite out-of-autoclave molding process. Focusing on interlaminar shear strength, the effects of pretreatment temperature, pretreatment time and vibration acceleration on the molding performance of composite components were analyzed sequentially using the orthogonal test design method; a scanning electron microscope (SEM) and optical digital microscope (ODM) were used to analyze the void content and fiber-resin bonding state of the specimens under different curing and molding processes. The results show that the influence order of the different vibration process parameters on the molding quality of the components was: vibration acceleration > pretreatment temperature > pretreatment time. Within the parameters analyzed in this study, the optimal vibration pretreatment process parameters were: pretreatment temperature of 90 °C, pretreatment time of 30 min, and vibration acceleration of 10 g. Using these parameters, the interlaminar shear strength of the component was 82.12 MPa and the void content was 0.37%. Compared with the microwave curing process, the void content decreased by 71.8%, and the interlaminar shear strength increased by 31.6%. The microscopic morphology and mechanical properties basically reached the same level as the standard autoclave process, which achieved a high-quality out-of-autoclave curing and molding manufacturing of aerospace composite components.

The vibration pretreatment–microwave curing process can achieve high-quality molding under low-pressure conditions and is widely used in the curing of resin-based composites. This study investigated the effects of the vibration pretreatment process parameters on the void content and the fiber weight fraction of T700/TRE231; specifically, their influence on the interlaminar shear strength and impact strength of the composite. Initially, an orthogonal experimental design was employed with interlaminar shear strength as the optimization target, where vibration acceleration was determined as the primary factor and dwell time as the secondary factor. Concurrently, thermogravimetric analysis (TGA) was performed based on process parameters that corresponded to the extremum of interlaminar shear strength, revealing a 2.17% difference in fiber weight fraction among specimens with varying parameters, indicating a minimal effect of fiber weight fraction on mechanical properties. Optical digital microscope (ODM) analysis identified interlaminar large-size voids in specimens treated with vibration energy of 5 g and 15 g, while specimens subjected to a vibration energy of 10 g exhibited numerous small-sized voids within layers, suggesting that vibration acceleration influences void escape pathways. Finally, impact testing revealed the effect of the vibration pretreatment process parameters on the impact strength, implying a positive correlation between interlaminar shear strength and impact strength.

Composite components with variable-thickness structures often suffer from insufficient forming pressure during curing due to complex pressure transfer in regions with abrupt thickness changes, which easily causes void defects and degrades component performance. In this study, a mechanical vibration-assisted double vacuum bag process is proposed. Finite element analysis of the vibration energy field in saturated porous composites is conducted, and curing experiments for variable-thickness specimens are designed. The effects of vibration, vacuum, and their synergy on void characteristics and mechanical properties are studied using microscopic characterization and mechanical tests. The results indicate that vibration can effectively facilitate gas discharge and accelerate resin flow, while the double vacuum bag process reduces gas discharge resistance in the early curing stage by delaying the vacuum negative pressure application, yet it also results in insufficient resin flow due to this delay. Through the synergistic optimization of vibration-assisted energy field parameters and the double vacuum bag process, gas-induced and flow-induced voids can be effectively suppressed while ensuring curing efficiency, reducing the macroscopic porosity of variable-thickness regions from 8.34% (single vacuum bag process) to 0.43%. This study provides a new approach for the high-quality curing and manufacturing of variable-thickness composite components.

Composite components with variable thickness structures often suffer from insufficient forming pressure during curing due to complex pressure transfer in regions with abrupt thickness changes, which easily causes void defects and degrades component performance. In this study, a mechanical vibration-assisted double vacuum bag process is proposed. Finite element analysis of the vibration energy field in saturated porous composites is conducted, and curing experiments for variable-thickness specimens are designed. The effects of vibration, vacuum, and their synergy on void characteristics and mechanical properties are studied using microscopic characterization and mechanical tests. The results indicate that vibration can effectively facilitate gas discharge and accelerate resin flow, while the double vacuum bag process reduces gas discharge resistance in the early curing stage by delaying the vacuum negative pressure application, yet it also results in insufficient resin flow due to this delay. Through the synergistic optimization of vibration-assisted energy field parameters and the double vacuum bag process, gas-induced and flow-induced voids can be effectively suppressed while ensuring curing efficiency, reducing the macroscopic porosity of variable-thickness regions from 8.34% (single vacuum bag process) to 0.43%. This study provides a new approach for the high-quality curing and manufacturing of variable-thickness composite components.