An Efficient Strength Evaluation Method Based on Shell-Fastener Model for Large Hybrid Joint Structures of C/SiC...

Area of Science:

• Materials Science
• Mechanical Engineering
• Aerospace Engineering

Background:

• Carbon fiber-reinforced silicon carbide (C/SiC) composites are crucial for aerospace thermal structures.
• Hybrid joints are necessary due to manufacturing complexity and cost, but intricate contact behavior hinders damage analysis.
• Existing solid and shell-fastener models have limitations in computational efficiency and stress field accuracy for these joints.

Purpose of the Study:

• To develop a computationally efficient and accurate method for analyzing damage and failure in hybrid joints of C/SiC composites.
• To establish a fractal contact stiffness model that incorporates bonded behaviors for intricate joint analysis.
• To validate a novel approach for predicting the failure mode and strength of multi-row hybrid joint structures.

Main Methods:

• Establishment of a fractal contact stiffness model considering bonded behaviors based on structural characteristics.
• Introduction of the strength envelope method to accurately describe complex stress fields within shell-fastener models.
• Experimental validation comparing predicted results with actual failure modes and strengths of multi-row hybrid joint structures.

Main Results:

• The fractal contact stiffness model demonstrates that bonded layers influence interface strength but not bearing strength in bolt/bonded hybrid joints.
• The strength envelope method effectively overcomes limitations of traditional shell-fastener models in complex stress analysis.
• The validated approach accurately predicts failure modes and strengths of multi-row hybrid joints with a 5.4% error, including bolt shear failure.

Conclusions:

• The developed fractal contact stiffness model and strength envelope method provide a robust foundation for designing large-scale C/SiC composite structures.
• This integrated approach enhances computational efficiency and predictive accuracy for complex hybrid joint behavior.
• The findings are critical for advancing the application of C/SiC composites in demanding aerospace environments.