Koheesioon

Koheesioon is a theoretical concept in materials science that denotes the internal cohesive forces binding the constituents of a bulk material. It is used to describe the strength of a material's internal matrix, as distinct from adhesion, which concerns interactions at interfaces with other materials. In models of fracture and delamination, koheesioon provides a scalar measure of the energy density required to separate two portions of the material without changing the surrounding environment.

Definition and measurement: Koheesioon is typically quantified as energy per unit volume or per unit area associated with creating a new internal surface, depending on the modeling framework. In practice, it is inferred from fracture-toughness data, tensile and compression tests, and material constants within continuum models. Some approaches relate it to cohesive energy density in polymer science, while others treat it as a parameter in phase-field or damage models.

Scope and applications: It applies to metals, ceramics, polymers and composites, particularly in studies of crack propagation, phase separation, and the stability of multilayer structures. Higher koheesioon correlates with improved resistance to crack initiation and delamination under homogeneous loading, while low values may indicate a material more prone to internal separation.

Etymology and status: The term koheesioon is a neologism used in some theoretical discussions to emphasize bulk cohesion. It is not universally standardized, and different communities may adopt related concepts such as cohesive energy density or fracture energy. Critics argue that conflating these related ideas under a single term can hinder comparability.