  In this work, we present crack propagation experiments evaluated by digital
image correlation (DIC) for a carbon black filled ethylene propylene diene
monomer rubber (EPDM) and numerical modeling with the help of variational
phase-field fracture. Our main focus is the evolution of cracks in one-sided
notched EPDM strips containing a circular hole. The crack propagation
experiments are complemented with investigations identifying the mechanical
material properties as well as the critical strain energy release rate. For
simulating the evolution of cracks with a given notch, phase-field fracture
modeling is a popular approach. To avoid volume-locking effects considering
fractures in nearly incompressible materials, a quasi-static phase-field
fracture model in its classical formulation is reformulated with the help of a
mixed form of the solid-displacement equation. The new established mixed
phase-field fracture model is applied to simulate crack propagation in
punctured EPDM strips by using the experimentally identified material
parameters with mixed finite elements. To discuss agreements and point out
challenges and differences, the crack paths, the maximal force response, the
traverse displacement at the crack start, as well as force-displacement curves
of the experimental and numerical results are compared.
