Recent advances in vegetable oil-based polymers and their composites

In this paper we present a novel engineering application of Origami, using it for both the exibility and the rigidity the folding patterns provide. The proposed Folded Textured Sheets have several inter- esting mechanical properties. The folding patterns are modelled as a pin-jointed framework, which allows the use of established structural engineering methods to gain insight into the kinematics of the folded sheet. The kinematic analysis can be naturally developed into a sti - ness matrix approach; by studying its softest eigenmodes, important deformations of a partially folded sheet can be found, which aids in the understanding of Origami sheets for engineering applications.

http://www2.eng.cam.ac.uk/~sdg/preprint/5OSME.pdf

Origami folding: A Structural Engineering Approach

With growing inclination towards the eco-friendly technology, natural fiber based polymer composite materials have been gaining a lot of momentum nowadays. The present review discusses the much research that has been carried out in the area of the epoxy-based composites reinforced with natural fibers. Influence of the various factors like the fiber content, fiber geometry, fiber size, surface treatment technique, and coupling agent on different properties like mechanical, thermal, behavior towards water absorption and others have been presented. It can be inferred that there is a need and scope for improvement of the surface properties of natural fiber using various methods like physical and chemical treatments, addition of coupling agents, etc. for the manufacturing of the composites having desired properties. These techniques not only modify surface morphology, but also improve other processing parameters like the hydrophilic character of fiber (which is desirable to be low), and hence improve several characteristics such as mechanical properties, thermal stability, water absorption and other considerations of the composites.

Natural fiber-mediated epoxy composites – A review

Thin-walled tubes subjected to axial crushing have been extensively employed as energy absorption devices in transport vehicles. Conventionally, they have a square or rectangular section, either straight or tapered. Dents are sometimes added to the surface in order to reduce the initial buckling force. This paper presents a novel thin-walled energy absorption device known as the origami crash box that is made from a thin-walled tube of square cross section whose surface is prefolded according to a developable origami pattern. The prefolded surface serves both as a type of geometric imperfection to lower the initial buckling force and as a mode inducer to trigger a collapse mode that is more efficient in terms of energy absorption. It has been found out from quasi-static numerical simulation that a new collapse mode referred to as the completed diamond mode, which features doubled traveling plastic hinge lines compared with those in conventional square tubes, can be triggered, leading to higher energy absorption and lower peak force than those of conventional ones of identical weight. A parametric study indicates that for a wide range of geometric parameters the origami crash box exhibits predictable and stable collapse behavior, with an energy absorption increase of 92.1% being achieved in the optimum case. The origami crash box can be stamped out of a thin sheet of material like conventional energy absorption devices without incurring in-plane stretching due to the developable surface of the origami pattern. The manufacturing cost is comparable to that of existing thin-walled crash boxes, but it absorbs a great deal more energy during a collision. [DOI: 10.1115/1.4024405]

Energy Absorption of Thin-Walled Square Tubes With a Prefolded Origami Pattern—Part I: Geometry and Numerical Simulation

Experimental study on crashworthiness of empty/aluminum foam/honeycomb-filled CFRP tubes

The use of natural fiber reinforcements for the production of ecofriendly composites has arisen considerable interest both in thermoplastic and thermoset based materials. In the latter case, the matrix is often an epoxy based polymer, which allows remarkable performance, but that cannot be considered eco-friendly since it is non-biodegradable and is produced from non-renewable sources. This strongly impairs the environmental friendly character of the resulting composite material. The aim of this work was to study the characteristics and performance of a thermoset bioepoxy resin, which is partly based on natural components, to be used in hemp reinforced laminates. The permeability of the hemp fabric as well as the rheological and thermal behavior of the resin were studied in view of their fabrication by resin infusion techniques. The results showed that laminated composites could be easily obtained with a vacuum assisted resin transfer molding process. Static, dynamic and vibration-damping tests were performed to evaluate limits and potentials of such biocomposites.

Composites with hemp reinforcement and bio-based epoxy matrix

A design solution for a crashworthy landing gear with a new triggering mechanism for the plastic collapse of metallic tubes

The development of autonomous healing material has an enormous scientific and technological interest. In this context, this research work deals with the investigation of autonomous healing behavior of epoxidized natural rubber (ENR) and its blends with ethylene methacrylic acid ionomers. The autonomous healing behavior of ENR and its blends containing two different ionomers [poly(ethylene-co-methacrylic acid sodium salt) (EMNa) and poly(ethylene-co-methacrylic acid zinc salt) (EMZn)] has been studied by ballistic puncture tests. Interestingly, EMNa/ENR blends exhibit complete healing just after the ballistic test but EMZn/ENR blends do not show full self-repairing. The healing efficiency has been evaluated by optical microscopy and a depressurized air-flow test. The healing mechanism has been investigated by characterizing thermal and mechanical properties of the blends. The chemical structure studied by FTIR and thermal analysis show that the ion content of ionomers and functionality of ENR has a significant influence on the self-healing behavior.

https://iopscience.iop.org/article/10.1088/0964-1726/21/3/035014/pdf

Gerardus Janszen

Papers

Composites with hemp reinforcement and bio-based epoxy matrix

A design solution for a crashworthy landing gear with a new triggering mechanism for the plastic collapse of metallic tubes

Autonomous healing materials based on epoxidized natural rubber and ethylene methacrylic acid ionomers

Novel system with damage initiated autonomous healing property based on heterogeneous blends of ethylene-methacrylic acid ionomer

Glass/Epoxy and Hemp/Bio based epoxy composites: Manufacturing and structural performances