High-energy impact testing of agglomerated cork at extremely low and high temperatures

Kaczyński, Paweł; Ptak, Mariusz; Wilhelm, Johannes; Fernandes, Fábio A. O.; Sousa, Ricardo J. Alves de

doi:10.1016/j.ijimpeng.2018.12.001

Cited by 37 publications

(29 citation statements)

References 38 publications

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“…In the case of the AC216 cork type, the difference was about 4.93 times larger and equaled 326 J (406 J for −30 °C and 80 J for 100 °C). The lack of temperature sensitivity was also confirmed in [35] on the basis of a CAMEA (cork agglomerates model for energy absorption) model defined as:E(d)=A⋅dB⋅CT where d —specimen deflection (mm), T —specimen temperature (°C), A , B , C —variables (-).…”

Section: Resultsmentioning

confidence: 69%

Development and Testing of Advanced Cork Composite Sandwiches for Energy-Absorbing Structures

et al. 2019

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Cork is a sustainable material with remarkable properties. In addition to its main application as wine stoppers, it has also been employed as a sound and thermal insulator in facades, building roofs, aeronautical applications, and, more recently, in impact energy absorption systems. In its natural form, cork is mainly used in wine stopper manufacturing, but for other applications, cork compounds are usually employed, which makes it possible to manufacture complex geometries with nearly isotropic behavior. In this work, an attempt was made to merge the desirable properties of two different cork materials (agglomerated and expanded black) into cork composite sandwich structures. These structures were tested according to impact conditions typically experienced by energy-absorbing liners used in personal safety devices. Additionally, the performance dependency on the working temperature was analyzed. The sole black, expanded cork (EC159) and agglomerated cork (AC199A and AC216) were tested in 500 J impacts. It was found that black cork was characterized by superior thermal stability, while expanded cork allowed absorbing high energies. In the second stage, the composites consisting of both tested materials were tested in 100 J impact scenarios. The combination of two materials of different properties enabled reduction of the peak force exerted on a helmet user’s head during the impact by about 10% compared to agglomerated specimens. Additionally, it was proved that there was no influence of the glue used to join different cork types.

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Section: Resultsmentioning

confidence: 69%

Development and Testing of Advanced Cork Composite Sandwiches for Energy-Absorbing Structures

et al. 2019

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“…Therefore, the explanation of this interesting phenomenon is related to the binder (polyurethane glue), impact energy and the binder reinforcement i.e., GNP or GO. First of all the cork material, in comparison to the used polyurethane binder, is a very good heat insulator with small heat capacity [32,33]. Once, during the dynamic test, a sample is impacted by the tup at the kinetic energy of 20.75 J, there are thermal effects observed in the samples—mainly due to its viscoelastic and viscoplastic nature of cork agglomerates.…”

Section: Resultsmentioning

confidence: 99%

Graphene-Enriched Agglomerated Cork Material and Its Behaviour under Quasi-Static and Dynamic Loading

et al. 2019

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The use of cork for a variety of applications has been gaining significance due to environmental concerns and political agendas. Consequently, its range of applications is growing rapidly. In this work, aiming to improve its mechanical response for crashworthiness applications, cork agglomerates were enriched by small quantities of graphene oxide or graphene nanoplates in order to observe a resulting improvement of the mechanical behaviour during quasi-static and dynamic compressive loading cases. To produce homogenous cork agglomerates including graphene, the material was previously dispersed into granulated cork using stirrers to achieve a good distribution. Then, the typical procedure of compression and curing was carried out. Magnified images attest a good dispersion of graphene into the cork matrix. Mechanical testing was performed for a variety of graphene concentrations (0.1, 0.5 and 1.0 weight %), becoming clear that the beneficial effect of including graphene (either oxide or nanoplates) is related to a later densification stage while keeping the same stress plateau levels.

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“…Tests were performed at room temperature, 40 • C, 60 • C, and 80 • C in order to investigate the influence of temperature on agglomerated cork and PVC flexural performances. The selected temperature range was dictated by the need to analyze the progression of agglomerated cork behavior at different temperatures up to an upper limit at which the mechanical properties of polyurethane binders normally experience a strong reduction [16]. Samples were conditioned for two hours before testing in order to achieve a homogeneous temperature across the whole specimen.…”

Section: Mechanical Characterizationmentioning

confidence: 99%

The Potential of Agglomerated Cork for Sandwich Structures: A Systematic Investigation of Physical, Thermal, and Mechanical Properties

et al. 2019

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Considering the major role played by sandwich structures in many fields where high stiffness-to-weight ratio is required, the selection of a suitable core material is of paramount importance. In order to face the environmental problems related to waste disposal, the selection of an eco-friendly core material is now included in the design criteria of sandwich structures. Agglomerated cork is recognized as a good solution that combines satisfactory mechanical performances and eco-sustainability. Many research studies individually addressed cork’s morphological, thermal, and mechanical features without providing a comprehensive overview of the relationships that exist between them. In this work, the investigation of the peculiar cork morphology allowed learning more about its good insulation capacity and its impressive recovery capability. The use of dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) clarified the influence of temperature on both flexural and compressive performances. The effect of testing parameters such as temperature and speed on agglomerated cork properties was validated through statistical analysis. Moreover, to highlight agglomerated cork advantages and drawbacks, the work provides also a comparison with more traditional polyvinylchloride (PVC) foams commonly used in industrial applications.

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High-energy impact testing of agglomerated cork at extremely low and high temperatures

Cited by 37 publications

References 38 publications

Development and Testing of Advanced Cork Composite Sandwiches for Energy-Absorbing Structures

Development and Testing of Advanced Cork Composite Sandwiches for Energy-Absorbing Structures

Graphene-Enriched Agglomerated Cork Material and Its Behaviour under Quasi-Static and Dynamic Loading

The Potential of Agglomerated Cork for Sandwich Structures: A Systematic Investigation of Physical, Thermal, and Mechanical Properties

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