Fracture of liquid crystal elastomers

Area of Science:

• Materials Science
• Polymer Science
• Mechanics of Materials

Background:

• Liquid crystal elastomers (LCEs) are advanced materials with unique anisotropic and viscoelastic properties.
• While LCE mechanical responses are well-studied, their fracture behavior and underlying mechanisms remain largely unexplored.
• Existing knowledge gaps include the impact of deformation-director coupling on LCE fracture paths and the absence of established fracture criteria.

Purpose of the Study:

• To investigate the fracture propagation behavior in liquid crystal elastomers (LCEs).
• To explore the influence of initial director orientation and stretching rate on LCE fracture paths.
• To establish predictive models for LCE fracture behavior.

Main Methods:

• Experimental stretching of edge-cracked monodomain LCE samples.
• Recording stress-stretch responses and observing crack propagation paths under varied conditions.
• Development and validation of a rate-dependent phase-field fracture model.

Main Results:

• Observed that cracks in LCEs can dynamically change direction during propagation.
• Demonstrated a strong dependence of crack path complexity on the initial director orientation and stretching rate.
• Validated a phase-field fracture model capable of accurately predicting complex LCE fracture paths.

Conclusions:

• The study elucidates the critical role of director-deformation coupling in LCE fracture.
• A validated computational model is presented for predicting LCE fracture behavior.
• Findings provide a foundation for designing LCEs with improved fracture resistance for advanced applications.