Corner Foam Versus Flat Foam: An Experimental Comparison on Cushion Performance

Abstract

Most cushion structures used in the industry are end caps, edge or corner foam. The bearing area and thickness of the cushioning obtained from cushion curves apply, in principle only, to flat foam because the specimens used to develop the cushion curves are flat foam samples. This study is aimed at finding the difference between the two foams in stress-strain relationship and dynamic impact. A hysteresis cycle compression test, in conjunction with digital image correlation techniques, and a shock cushion test were performed to assess the static stress and strain, energy dissipated and maximum acceleration of flat and corner foams. The study found that the static stress of the corner foam that occurred during the compression testing is 23% higher in average than the flat foam, depending on the compression speed. The shock cushion curve of the corner foam showed a similar pattern as the flat cushion curve but was shifted horizontally to the right as a result of the increased static stress. This study recommends that the conventional cushion curve should be shifted to the right horizontally by about 23-35% in order for a packaging designer to apply it for corner foam.

A preliminary study of cushion properties of a 3D printed thermoplastic polyurethane Kelvin foam

“…A number of diagrams have been suggested for characterizing cushion factor based on the compression stress-stain curve and drop platen test. 1,[9][10][11][12][13][14][15] These methods are summarized in Figure 3.…”

“…During the drop platen test, at the moment when the platen falls to the ground, the original potential energy is absorbed by dynamic deformation of the foam and can be described by Equation 1 [9][10][11][12][13][14][15] :…”

A phenomenological constitutive modelling of polyethylene foam under multiple impact conditions

“…Because of the light weight and good restitution properties, polymeric foam has been extensively applied for energy absorption and packaging design . Polyethylene (PE) foam is the preferred choice in terms of its outstanding recovery characteristics to withstand multi‐impact by comparing with polystyrene (PS) foam . In a traditional packaging design, the thickness and area of section are calculated by using cushion curves of the foam material, which are laborious and time consuming.…”

“…1,2 Polyethylene (PE) foam is the preferred choice in terms of its outstanding recovery characteristics to withstand multi-impact by comparing with polystyrene (PS) foam. 3 In a traditional packaging design, the thickness and area of section are calculated by using cushion curves of the foam material, which are laborious and time consuming. To simplify the process for determining cushion curves, Li 4 presented the cushion curves of PE foam based on dynamic factors defined by quasi-static and dynamic drop tests, which is presented by Sek.…”

Primary Resonance Behaviour of a Nonlinear, Viscoelastic Model of Expanded Polymer Cushion Material

“…[4][5][6] Techniques for characterizing the dynamic behaviour of expanded polymer foams and predicting a product's response to that behaviour are also prevalent in literature. [7][8][9][10][11][12][13][14] Missing within the field of packaging science are standardized methods and agreed-upon models for determining the vibration response of packaging foams that capture their nonlinear dynamic behaviour in response to a periodic excitation. Recent work employs a distributed parameter model to predict the vibration response of expanded polymer foam to small strain inputs typical in the vehicle transport of packaged products 15,16 .…”