Marshmallow deformability

Although marshmallows are cellular solids, they exhibit a deformability pattern that is atypical for cellular solids of the kinds classified by Ashby (1983). The marshmallow deformability is characterized by the absence of a prominent shoulder in the stress-strain relationships as shown schematically in Figure 10.6 (top). 

Rigid specimens (e.g., apple, cheddar cheese) often exhibit a sudden decrease in force (stress) after a certain amount of deformation (maximum strain). At this point the specimen has fractured. Maximum stress and strain values may vary depending on the chosen specimen. Specimens that are weakly structured and tend to flow under lubricated compression (e.g., mozzarella cheese, marshmallow) demonstrate squeezing flow. As a result, the force (stress) continually increases as the specimen deformation (strain) increases. These materials do not fracture, but continue to stretch radially while under compression. Both rigid and soft specimens of the same material may exhibit varying characteristics depending on the deformation rate and the aspect ratio of each specimen. 

Figure 10.6. Top Sehematie view of the foree-deformation relationships of marshmallows. Notiee the absenee of a shoulder. After Kaletune et al. (1992). Bottom. Sehematie view of how the degree of elastieity ean be assessed from a eompression-deeompression eurve. (Notiee that the area under the stress-stress strain eurve has work per unit volume units and that the degree of elastieity ean be defined as the reeoverable/total work ratio.)...

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