Mixed Mode Crack Propagation in Polymers Using a Discrete Lattice Method.

Area of Science:

• Materials Science
• Computational Mechanics
• Polymer Physics

Background:

• Polymer fracture behavior is crucial for material design.
• Existing discrete models often limit Poisson's coefficient selection.
• Continuum and discrete methods are used for crack propagation analysis.

Purpose of the Study:

• To present a numerical and experimental analysis of crack propagation in polymethylmethacrylate (PMMA) beams.
• To introduce a discrete lattice model capable of simulating quasi-static fracture problems.
• To overcome limitations in Poisson's coefficient selection in discrete fracture models.

Main Methods:

• Developed a discrete numerical model using a regular triangular lattice with axial and normal interaction springs.
• Incorporated a fracture criterion with a bilinear softening law, including fracture energy and progressive damage.
• Conducted quasi-static three-point bending tests on PMMA beams with central and eccentric notches.
• Validated the numerical model against experimental results.

Main Results:

• The proposed lattice model accurately simulates quasi-static fracture problems.
• Numerical results closely match experimental data for crack patterns.
• The model effectively predicts peak load and initial stiffening behavior.
• The model successfully addresses limitations in Poisson's coefficient selection.

Conclusions:

• The discrete lattice model demonstrates significant capacity for simulating polymer fracture.
• The model provides a viable alternative to continuum methods for crack propagation studies.
• The approach allows for accurate prediction of fracture mechanics in polymers like PMMA.