English: This diagram depicts the concept behind a family of models known as cohesive zone fracture models. ${\displaystyle \sigma }$ represents the cohesive traction (sometimes denoted ${\displaystyle \sigma _{c}}$), ${\displaystyle a}$, the crack length, ${\displaystyle \delta }$, the crack separation displacement, ${\displaystyle \sigma ^{\infty }}$, the remote applied stress, and ${\displaystyle r_{p}}$ the length of the plastic zone. The tractions in this diagram are more similar to the atomistically derived tractions from Barenblatt models using an exponential relationship between crack separation displacement and cohesive traction. The Dugdale model on the other hand assumes cohesive traction is a constant and can be considered a special case of the cohesive zone model.^[1] This work is an adaptation of the Dugdale fracture model diagram by Suresh^[2] (adapted with permission), but also incorporates concepts from Sun et al. ^[3], and Shi^[4]. The original models were created by Dugdale ^[5]and Barenblatt^[6]