Impact behavior of energy absorbing helmet liners with PA12 lattice structures: A computational study

Nasim, Mohammad; Hasan, Md. Jahid; Galvanetto, Ugo

doi:10.1016/j.ijmecsci.2022.107673

Cited by 28 publications

(6 citation statements)

References 38 publications

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“…Nasim et al, explored the performance of three different uniform lattice types which were additively manufactured with polyamide 12 and incorporated into a protective liner for a motorcycle helmet [51]. Simulative and physical testing showed greatly increased protection by some lattice types compared to EPS liners, while others fell short.…”

Section: Functionally Graded Lattice Structuresmentioning

confidence: 99%

“…No physical tests of the lattice structures were performed by them, only material testing and simulative studies of the impact scenario. Similarly, Nasim et al [51] investigated only part of the helmet geometry, albeit with a realistic dummy head model both in simulations and in physical testing. Their choice was due to the meshing of the lattice with tetrahedral elements, causing a considerable simulation duration and potential numerical instabilities stemming from severe element distortion.…”

Section: Scopementioning

confidence: 99%

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Optimizing the Thickness of Functionally Graded Lattice Structures for High-Performance Energy Absorption: A Case Study Based on a Bicycle Helmet

Decker,

Kedziora

2024

Applied Sciences

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This study explores the complete production chain of designing, optimizing, and Additive Manufacturing (AM) of a helmet incorporating a functionally graded lattice structure (FGLS). The potential of FGLSs in impact energy absorption tasks is investigated, along with the demonstration of a novel lattice optimization approach. Fifteen conformal, strut-based lattices are implemented in a realistic mountain bike helmet geometry and simulated in a standardized impact scenario in accordance with EN 1078. One model is subjected to the optimization procedure, produced, and physically tested. The study addresses limitations in prior research, emphasizing manufacturability in an AM context, lattice type exploration, the comparability of different unit cell types, and numerical modeling choices. The findings provide insights into the performance of lattice structures during impact, emphasizing practical engineering aspects such as design choices, optimization approaches, and manufacturing constraints.

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Section: Functionally Graded Lattice Structuresmentioning

confidence: 99%

Section: Scopementioning

confidence: 99%

Optimizing the Thickness of Functionally Graded Lattice Structures for High-Performance Energy Absorption: A Case Study Based on a Bicycle Helmet

Decker,

Kedziora

2024

Applied Sciences

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“…Selective laser sintering (SLS) is a powder-based AM process that fabricates parts using a laser source by sintering polymer powders layer by layer. By using the SLS technology, without additional support material, complex parts such as cellular solids (CS) (Ren et al , 2019; Nasim et al , 2022), topology-optimised components (Kumar and Arumaikkannu, 2019), and customized parts can be manufactured precisely with lower material usage (Sillani et al , 2021). CS consist of pores and solid plates or struts in its topology that help dissipate the applied energy throughout its structure to reduce the damage (Benedetti et al , 2021).…”

Section: Introductionmentioning

confidence: 99%

Quasi-static compression and energy absorption behaviour of polymeric selective laser sintered open cell lattices under varying relative densities

2024

RPJ

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Purpose The purpose of this paper is to compare the influence of relative density (RD) and strain rates on failure mechanism and specific energy absorption (SEA) of polyamide lattices ranging from bending to stretch-dominated structures using selective laser sintering (SLS). Design/methodology/approach Three bending and two stretch-dominated unit cells were selected based on the Maxwell stability criterion. Lattices were designed with three RD and fabricated by SLS technique using PA12 material. Quasi-static compression tests with three strain rates were carried out using Taguchi's L9 experiments. The lattice compressive behaviour was verified with the Gibson–Ashby analytical model. Findings It has been observed that RD and strain rates played a vital role in lattice compressive properties by controlling failure mechanisms, resulting in distinct post-yielding responses as fluctuating and stable hardening in the plateau region. Analysis of variance (ANOVA) displayed the significant impact of RD and emphasised dissimilar influences of strain rate that vary to cell topology. Bending-dominated lattices showed better compressive properties than stretch-dominated lattices. The interesting observation is that stretch-dominated lattices with over-stiff topology exhibited less compressive properties contrary to the Maxwell stability criterion, whereas strain rate has less influence on the SEA of face-centered and body-centered cubic unit cells with vertical and horizontal struts (FBCCXYZ). Practical implications This comparative study is expected to provide new prospects for designing end-user parts that undergo various impact conditions like automotive bumpers and evolving techniques like hybrid and functionally graded lattices. Originality/value To the best of the authors' knowledge, this is the first work that relates the strain rate with compressive properties and also highlights the lattice behaviour transformation from ductile to brittle while the increase of RD and strain rate analytically using the Gibson–Ashby analytical model.

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“…Advances in computational modelling now offers a route to developing novel helmet liners that could exceed contemporary materials' performance [29][30][31]. Furthermore, the rise of additive manufacturing presents a viable route to achieving otherwise unobtainable material structures [32][33][34][35]. Additively manufactured cellular structures have previously been evaluated with respect to the loading conditions of a helmet impact.…”

Section: Introductionmentioning

confidence: 99%

Optimisation of an elastomeric pre-buckled honeycomb helmet liner for advanced impact mitigation

Adams

Soe

Theobald

2023

Smart Mater. Struct.

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Advances in computational modelling now offer an efficient route to developing novel helmet liners that could exceed contemporary materials' performance. Furthermore, the rise of accessible additive manufacturing presents a viable route to achieving otherwise unobtainable material structures. This study leverages an established finite element-based approach to the optimisation of cellular structures for the loading conditions of a typical helmet impact. A novel elastomeric pre-buckled honeycomb structure is adopted and optimised, the performance of which is baselined relative to vinyl nitrile foam under direct and oblique loading conditions. Results demonstrate that a simplified optimisation strategy is scalable to represent the behaviour of a full helmet. Under oblique impact conditions, the optimised pre-buckled honeycomb liner exceeds the contemporary material performance when considering computed kinematic metrics head and rotational injury criterion, by up to 49.9% and 56.6%. Furthermore, when considering tissue-based severity metrics via finite element simulations of a human brain model, maximum principal strain and cumulative strain density measures are reduced by 14.9% and 66.7% when comparing the new material, to baseline.

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Impact behavior of energy absorbing helmet liners with PA12 lattice structures: A computational study

Cited by 28 publications

References 38 publications

Optimizing the Thickness of Functionally Graded Lattice Structures for High-Performance Energy Absorption: A Case Study Based on a Bicycle Helmet

Optimizing the Thickness of Functionally Graded Lattice Structures for High-Performance Energy Absorption: A Case Study Based on a Bicycle Helmet

Quasi-static compression and energy absorption behaviour of polymeric selective laser sintered open cell lattices under varying relative densities

Optimisation of an elastomeric pre-buckled honeycomb helmet liner for advanced impact mitigation

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