Load–compression behavior of flexible foams

Abstract

The load–compression behavior of a foam reflects its geometric structure and the physical properties of the matrix polymer. Quantitative relations between these parameters have been established in the present study. Based on both theoretical analyses and experimental data obtained on a flexible polyurethane foam, it is shown that the compressive stress can be factored into the product of two terms: (1) a dimensionless function of the compressive strain, ψ(ε), calculated from experimental load–compression data and reflecting the buckling of the foam matrix; and (2) a factor, εEf, where Ef is the apparent Young's modulus of the foam (which is a function primarily of the modulus of the base polymer E0 and of the volume fraction of polymer, φ). Thus the compressive stress behavior of a foamed polymer is determined by E0, φ, and the matrix geometry, the latter described by the function ψ(ε). Using these established relations, it now is possible to delineate precisely the structural features a foam must possess—density, cell shape and size distribution, and modulus of the base polymer—to meet a given load–compression specification.

Compressive deformation and energy absorbing characteristic of foamed aluminum

“…[4,8,9] Thornton et al indicated in their research [4] that the efficiency usually reached a maximum at some intermediate strain (about 0.5 to 0.6), and this strain seemed to be irrelevant to the relative density and the matrix composition. Different results were obtained in the present study.…”

“…There have been several models describing the compressive deformation and mechanical properties of cellular materials, [8][9][10][11] the more recent ones of which are presented by Ashby and Gibson et al [9] They predicted that the compressive stress-strain curve of cellular solids, either elastomeric, plastic, or brittle ones, can be divided into three regions: the linear elastic, the plateau, and the densification. The extent of each region depends on its relative density and responds to different mechanical responses.…”

Microcellular foaming of polymethylmethacrylate in a batch supercritical CO2 process: Effect of microstructure on compression behavior

“…An example of a phenomenological model was stated by Rusch. [39][40][41] However, a drawback of the model is its inaccuracy in describing the densification phase when, a consequence of the compression, internal voids progressively disappears. On the other hand, micromechanical models take into account the deformation mechanisms of the cell structure under loading, using several adimensional parameters that reflect these effects.…”

Anisotropic mechanical behavior of magnetically oriented iron particle reinforced foams

“…3 Elastic modulus, yield point, 3 and length of stress plateau 4,5 are the main parameters to be considered in foam design for specific applications.…”