Stress-strain relationship foams

A simple bubble machine is devised and successfully applied in characterising lightly crosslinked PE resins for foam expansion. The biaxial stress-strain relationship is deduced from the air injection rate and pressure. The effects of strain rate, temperatnre and crosslinker level on the stress-strain behavionr are investigated. Uniaxial extension experiments are also performed and compared with biaxial extension data. 5 refs. 

Mathematical Characterization of the Compressive Stress-Strain Relationship of Polymeric Foams, Breads and Cakes... 

Typical sigmoid compressive stress-strain relationships of both synthetic foams and bakery products can be expressed mathematically by a variety of empirical models among them (Swyngedau et al. 1991) ... 

Figure 10.3. The stress strain relationship of a poljmrethane and bread crumb foams fitted with four erapirieal models (see text). From Swyngedau et al. (1991).

This behaviour concerning the cumulative effect of functionality and molecular weight of oligo-polyols is observed in the case of PU foams (flexible, semiflexible and rigid) based on stress-strain relationship [2, 12]. 

When particles move on a surface while under a rotating and compressed foam roll, the surface is subjected to normal ( a ) and shear ( t ) stresses. The total contact stress can be determined from a strain energy relationship. 

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