Materials and structures with negative Poisson's ratio exhibit a counter-intuitive behaviour. Under uniaxial compression (tension), these materials and structures contract (expand) transversely. The materials and structures that possess this feature are also termed as 'auxetics'. Many desirable properties resulting from this uncommon behaviour are reported. These superior properties offer auxetics broad potential applications in the fields of smart filters, sensors, medical devices and protective equipment. However, there are still challenging problems which impede a wider application of auxetic materials. This review paper mainly focuses on the relationships among structures, materials, properties and applications of auxetic metamaterials and structures. The previous works of auxetics are extensively reviewed, including different auxetic cellular models, naturally observed auxetic behaviour, different desirable properties of auxetics, and potential applications. In particular, metallic auxetic materials and a methodology for generating 3D metallic auxetic materials are reviewed in details. Although most of the literature mentions that auxetic materials possess superior properties, very few types of auxetic materials have been fabricated and implemented for practical applications. Here, the challenges and future work on the topic of auxetics are also presented to inspire prospective research work. This review article covers the most recent progress of auxetic metamaterials and auxetic structures. More importantly, several drawbacks of auxetics are also presented to caution researchers in the future study.

Auxetic metamaterials and structures: a review

Mechanical metamaterials associated with stiffness, rigidity and compressibility: a brief review

Review of magnesium-based biomaterials and their applications

Material properties can be tailored through modification of their geometry or architecture. With this concept, a lot of smart materials, metamaterials, and smart structures have been developed. Auxetic materials and structures are a novel class of materials which exhibit an interesting property of negative Poisson's ratio. By virtue of the auxetic behavior, mechanical properties such as fracture toughness, indentation resistance, etc., can be improved. In order to exploit the interesting properties of auxetic materials, several potential applications of auxetic materials have been explored in medical, sports, automobile, defense, etc. Design and modeling of novel auxetic materials and structures is still on the way. Here, the article focuses upon the different aspects of auxetic materials and structures. A comprehensive updated review of auxetic materials, their types and properties, and applications has been presented. This paper also discusses the design and modeling approaches of auxetic structures.

Three Decades of Auxetics Research − Materials with Negative Poisson's Ratio: A Review

Stereolithography is a solid freeform technique (SFF) that was introduced in the late 1980s Although many other techniques have been developed since then, stereolithography remains one of the most powerful and versatile of all SFF techniques It has the highest fabrication accuracy and an increasing number of materials that can be processed is becoming available In this paper we discuss the characteristic features of the stereolithography technique and compare it to other SFF techniques The biomedical applications of stereolithography are reviewed, as well as the biodegradable resin materials that have been developed for use with stereolithography Finally, an overview of the application of stereolithography in preparing porous structures for tissue engineering is given

A review on stereolithography and its applications in biomedical engineering

Auxetic materials are endowed with a behavior that contradicts common sense, when subjected to an axial tensile load they increase their transverse dimension. In case of a compression load, they reduce their transverse dimension. Consequently, these materials have a negative Poisson’s ratio in such direction. This paper reviews research related to these materials. It presents the theories that explain their deformation behavior and reveals the important role represented by the internal structure. Their mechanical properties are explored and some potential applications for these materials are shown.

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Auxetic materials — A review

Olive pomace as a valuable source of bioactive compounds: A study regarding its lipid- and water-soluble components.

https://repositorium.sdum.uminho.pt/bitstream/1822/26066/1/The%20effect%20%20of%20Sc%20additions%20on%20the%20microstructure.pdf

The effect of Sc additions on the microstructure and age hardening behaviour of as cast Al–Sc alloys

https://repositorium.sdum.uminho.pt/bitstream/1822/15739/1/Influence%20of%20ultrasonic%20melt%20treatment%20on%20microstructure%20and%20mechanical%20properties%20of%20AlSi9Cu3%20alloy.pdf

Influence of ultrasonic melt treatment on microstructure and mechanical properties of AlSi9Cu3 alloy

https://repositorium.sdum.uminho.pt/bitstream/1822/12420/1/Recycling%20of%20aluminium%20swarf%20by%20direct%20incorporation%20in%20aluminium%20melts.pdf

Hélder Puga

Papers

Auxetic materials — A review

Olive pomace as a valuable source of bioactive compounds: A study regarding its lipid- and water-soluble components.

The effect of Sc additions on the microstructure and age hardening behaviour of as cast Al–Sc alloys

Influence of ultrasonic melt treatment on microstructure and mechanical properties of AlSi9Cu3 alloy

Recycling of aluminium swarf by direct incorporation in aluminium melts