Rate- and temperature-dependent ductile-to-brittle fracture transition: Experimental investigation and phase-field analysis for toffee

TL;DR

This study investigates how rate and temperature influence the ductile-to-brittle fracture transition in toffee-like caramel, combining experimental data with phase-field modeling to understand the underlying mechanics.

Contribution

It provides a comprehensive experimental analysis and develops a phase-field model to predict rate- and temperature-dependent fracture behavior in soft materials.

Findings

Fracture behavior varies significantly with deformation rate and temperature.

The phase-field model accurately predicts the ductile-to-brittle transition.

Coupling between deformation and fracture resistance is crucial for understanding material response.

Abstract

The mechanical behaviour of many materials, including polymers or natural materials, significantly depends on the rate of deformation. As a consequence, a rate-dependent ductile-to-brittle fracture transition may be observed. For toffee-like caramel, this effect is particularly pronounced. At room temperature, this confectionery may be extensively deformed at low strain rates, while it can behave highly brittle when the rate of deformation is raised. Likewise, the material behaviour does significantly depend on temperature, and even a slight cooling may cause a significant embrittlement. In this work, a thorough experimental investigation of the rate-dependent deformation and fracture behaviour is presented. In addition, the influence of temperature on the material response is studied. The experimental results form the basis for a phase-field modelling of fracture. In order to derive the governing equations of the model, an incremental variational principle is introduced. By means of the validated model, an analysis of the experimentally observed ductile-to-brittle fracture transition is performed. In particular, the coupling between the highly dissipative deformation behaviour of the bulk material and the rate-dependent fracture resistance is discussed.