Nonlinear Response of a Polycarbonate in Post-Yield Cyclic Tests

Area of Science:

• Materials Science
• Polymer Mechanics
• Solid Mechanics

Background:

• Glassy amorphous polymers exhibit complex mechanical behaviors.
• Understanding polycarbonate's response under various stress conditions is crucial for material modeling.
• Viscous effects can influence polymer mechanical properties at different strain rates.

Purpose of the Study:

• To investigate the mechanical behavior of polycarbonate under cyclic tensile, compression, and torsion.
• To analyze strain rates that minimize viscous effects for accurate mechanical response assessment.
• To contribute to the development of mathematical models for glassy amorphous polymers.

Main Methods:

• Cyclic tensile, compression, and torsion tests were performed on polycarbonate.
• Measurements included axial, transverse, and shear strains.
• Tests were conducted at strain rates designed to reduce viscous effects.

Main Results:

• Tensile tests showed nonlinear elasticity, ratcheting, plasticity, and increased volumetric strain.
• Compression tests revealed nonlinear elasticity with unexpected positive plastic axial and volumetric strains.
• Torsion tests demonstrated a nonlinear elastic relationship and positive plastic volumetric strains under deviatoric stress.

Conclusions:

• Polycarbonate exhibits complex nonlinear elastic and plastic behaviors under various loading conditions.
• Deviatoric stress can induce volumetric plastic strains in polycarbonates.
• Findings are vital for advancing mathematical models of glassy amorphous polymers.