Abstract:
A fracture model for a composite quasi-brittle material is proposed, assuming that different structural elements are involved in crack formation depending on the strain rate. The deformation of the material may result from either external mechanical loading or self-expansion due to temperature changes. A dependence is introduced between the critical strain rate of the material and its elastic properties measured using the static methods. At strain rates below the critical threshold, fracture initiates in the weaker component of the composite, whereas at rates exceeding the critical value, failure becomes volumetric, involving all structural elements in crack formation. For such materials, the critical strain rate at which the fracture mechanism changes is calculated. The theoretical results are validated through laboratory static and dynamic strength tests of the industrial refractories. It is established that, in practice, the grain frame of the composite material is involved in crack formation when the strain rate exceeds the calculated critical value.
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