Deformation and energy absorption of polymer foams as a function of 2‐D indenter and absorber geometries

Abstract

Amherst. Massachusetts 01 003Two-dimensional indenters (flat plate and cylinder) were used to compress rectangular and trapezoidal foam energy absorbers as a function of polymer, foam density, and thickness. An increased deformation volume formed when the indenter contact area was less than the foam absorber area, resulting in both increased energy absorption and stress transmitted to the indenter (i.e., "load spreading"). The deformation volume was trapezoidal, not prismatic, and was characterized by the indenter geometry, dlmensions, and foam thickness. Conservative energy absorber design can be achieved by using "energy absorption diagrams" that account for the indenter (i.e., product) and absorber geometry and degree of load spreading. MTRODUCTIONhe use of energy absorbers in packaging is a T necessity, whether it is to protect a product during shipping, a passenger in an automobile, or the head of a cyclist. Polymer foams are ubiquitous as packaging materials because they are effective, inexpensive energy absorbers that can be easily shaped to conform to complex product geometries. Current design practice relies on "cushioning curves," which are strictly applicable only to objects with planar contact areas impacting foam cushions of equal or lesser area (1, 2). When combined with "drop testing," however, this method succeeds in p r e tecting most packages, but it is questionable whether the polymer foam, thickness, and geometry are optimum (3).Regardless, future packaging trends are expected to demand decreased shipping and warehouse costs bYg package volume without loss of protec-

Indentation resistance of an aluminium foam

“…Early work on the indentation of foams has suggested that it is controlled to a large extent by its compressive strength [1,2]. Preliminary work on the indentation of foams was presented by Andrews et al [3], Onck et al [4], Gibson and Ashby [5], Tulliani et al [6], Stupak and Donovan [7] and Prakash et al [8]. The average indentation pressure was reported as a function of indenter geometry and contact area, with limited experimental data.…”

A bumper model with dynamic contact stiffness for simulations of pedestrian legform impacts

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Static Indentation Response of H30 Foam ‐ an Experimental and Computational Study

“…Stupak and Donovan [13] studied non-linear deformation mechanisms and energy absorption capacities of two-dimensional test specimens of cellular foam materials subjected to indentation.…”