Decoupling shear and compression properties in composite polymer foams by introducing anisotropy at macro level

Abstract

Anisotropy in foams generally originates from cell elongation in a certain direction. In this study, a composite concept is utilized to create anisotropy in foams at macro level. For this, layered composite foam is proposed by combining discrete layers of expanded polystyrene foam foam with different densities. The layers are positioned in parallel with the prime loading direction. The compression and biaxial combined shear-compression behavior of the composite foams are studied and compared with single-layer expanded polystyrene foam of equivalent density. The biaxial shear-compression test results demonstrate that the composite concept enables to decouple shear and compression properties of foam for a given overall density. In compression loading, the composite foam behavior is similar to that of single-layer foam of similar density, while in biaxial loading, the composite foam shows lower shear resistance than single-layer foam. Moreover, in biaxial loading, parameters such as the number of layers and the density difference between the high- and low-density layers affect the extent of decrease in shear resistance, while the compression stress component depends solely on the overall density of the composite foam. One of the potential applications of this behavior could be in protective helmets for mitigation of the head rotational acceleration.

Keywords

Composite foam expanded polystyrene biaxial loading decoupled shear and compression macro anisotropy

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References

Mills

Fitzgerald

Gilchrist

et al . Polymer foams for personal protection: cushions, shoes and helmets. Compos Sci Technol 2003; 63: 2389–2400

Mills

NJ.

Polymer foams handbook: engineering and biomechanics applications and design guide. Oxford: Butterworth Heinemann, 2007.

Zhang

and Ashby

MF.

Mechanical selection of foams and honeycombs used for packaging and energy absorption.

J Mater Sci 1994; 29: 157–163.

Gibson

and Ashby

MF.

Cellular solids: structure and properties. 2nd ed. Cambridge: Cambridge University Press, 1997.

Rossacci

and Shivkumar

Bead fusion in polystyrene foams

. J Mater Sci 2003; 38: 201–206.

Tzeng

and Lee

MC.

Mechanical properties of impact absorbing liner of motorcycle helmets. Am Soc Mech Eng 1989; 98: 381–384.

Miltz

and Ramon

Energy absorption characteristics of polymeric foams used as cushioning materials.

Polym Eng Sci 1990; 30:129–133.

Di Landro

Sala

and Olivieri

Deformation mechanisms and energy absorption of polystyrene foams for protective helmets.

Polym Test 2002; 21: 217–228.

Forero-Rueda

Cui

and Gilchrist

Optimisation of energy absorbing liner for equestrian helmets. Part I: layered foam liner.

Mater Des 2009; 30: 3405–3413.

10.

Cui

Forero-Rueda

and Gilchrist

Optimisation of energy absorbing liner for equestrian helmets. Part II: functionally graded foam liner. Mater Des 2009; 30: 3414–3419.

11.

Cui

Kiernan

and Gilchrist

Designing the energy absorption capacity of functionally graded foam materials.

Mater Sci Eng A 2009; 507: 215–22.

12.

Doyoyo

and Wierzbicki

Experimental studies on the yield behavior of ductile and brittle aluminum foams.

Int J Plasticity 2003; 19: 1195–1214.

13.

Mohr

and Doyoyo

Experimental investigation on the plasticity of hexagonal aluminum honeycomb under multiaxial loading.

J Appl Mech 2004; 71: 375–385.

14.

Benderly

and Putter

Characterization of the shear/compression failure envelope of Rohacell foam.

Polym Test 2004; 23: 51–57.

15.

Kintscher

Kärger

Wetzel

et al . Stiffness and failure behaviour of folded sandwich cores under combined transverse shear and compression. Compos Part A–Appl S 2007; 38: 1288–1295.

16.

Mosleh

Vanden Bossche

Depreitere

et al . Effect of polymer foam anisotropy on energy absorption during combined shear-compression loading. J Cell Plast 2017. DOI: 10.1177/0021955X17720156

17.

Richter

Otte

Lehmann

et al . Head injury mechanisms in helmet protected motorcyclists: prospective multicenter study. J Trauma 2001; 51: 949–958.

18.

Holborn

AHS.

Mechanics of head injuries.

The Lancet 1943; 242: 438–441.

19.

Gennarelli

and Thibault

LE.

Biomechanics of acute subdural hematoma.

J Trauma 1982; 22: 680–686.

20.

Bourdet

Deck

Carreira

et al . Head impact conditions in the case of cyclist falls. Proc Inst Mech Eng Part P: J Sport 2012; 226: 282–289.

21.

Depreitere

Goffin

Van Lierde

et al . EP1 776 022 B1, 2008.

22.

Vanden Bosche

Mosleh

Depreitere

et al . Anisotropic polyethersulfone foam for bicycle helmet liners to reduce rotational acceleration during oblique impact. Proc Inst Mech Eng Part P: J Eng Med 2017; 231(9): 851–861. DOI: 10.1177/0954411917711201

23.

Huber

and Gibson

LJ.

Anisotropy of foams.

J Mater Sci 1988; 23: 3031–3040.

24.

Kleiner

Radojewski

Muhlbauer

et al . Laminates of polyethylene foam with anisotropic pore structure, 1997.

25.

Oliveira-Salmazo

Lopez-Gil

Silva-Bellucci

et al . Natural rubber foams with anisotropic cellular structures: mechanical properties and modelling. Ind Crop Prod 2016; 80: 26–35.

26.

Bernardo

Laguna-Gutierrez

Lopez-Gil

et al . Highly anisotropic crosslinked HDPE foams with a controlled anisotropy ratio: production and characterization of the cellular structure and mechanical properties. Mater Des 2017; 114: 83–91.

27.

Vanden

Bosche K.

Development and characterization of novel anisotropic foam for bicycle helmets. PhD Thesis. KU Leuven libraries, 2016.