Monotonic and Cyclic Loading/Unloading Tensile Behavior of 3D Needle-Punched C/SiC Ceramic-Matrix Composites

Area of Science:

• Materials Science
• Mechanical Engineering
• Composite Materials

Background:

• Ceramic matrix composites (CMCs) like C/SiC are crucial for high-temperature applications.
• Understanding their mechanical behavior under monotonic and cyclic loading is vital for structural integrity.
• Needle-punched C/SiC composites offer unique microstructural characteristics influencing performance.

Purpose of the Study:

• To investigate the monotonic and cyclic tensile behavior of four distinct 3D needle-punched C/SiC composites.
• To characterize tensile damage and fracture behavior using micro-parameters.
• To establish relationships between mechanical behavior, damage parameters, and micro-damage mechanisms.

Main Methods:

• Monotonic and cyclic tensile loading/unloading tests were performed on C/SiC composites.
• Micro-parameters including tensile tangent modulus, strength, fracture strain, unloading residual strain, and hysteresis loops were analyzed.
• Scanning Electron Microscopy (SEM) was used to observe fracture surfaces and identify micro-damage mechanisms.

Main Results:

• Increased fiber volume fraction along the loading direction positively correlated with higher initial tangent modulus, tensile strength, and fracture strain.
• Higher fiber volume fraction led to decreased unloading residual strain, peak strain, hysteresis width, and hysteresis area under cyclic loading.
• Observed micro-damage mechanisms included matrix cracking, interface debonding, and fiber fracture/pullout.

Conclusions:

• Fiber volume fraction is a critical parameter influencing the tensile mechanical properties and damage evolution of 3D needle-punched C/SiC composites.
• Established clear links between macroscopic mechanical response, quantifiable damage parameters, and underlying microscopic failure modes.
• The study provides valuable data for the design and application of these advanced C/SiC composites.