Epoxy resins are one of the most widely used thermosets in different engineering fields, due to their chemical resistance and thermo-mechanical properties. Recently, bio-based thermoset resin systems have attracted significant attention given their environmental benefits related to the wide variety of available natural resources, as well as the resulting reduction in the use of petroleum feedstocks. During the last two decades, considerable improvement on the properties of bio-sourced resins has been achieved to obtain performances comparable to petroleum-based systems. This paper reviews recent advances on new bio-based epoxy resins, derived from natural oils, natural polyphenols, saccharides, natural rubber and rosin. Particular focus has been given to novel chemical formulations and resulting mechanical properties of natural derived- epoxies, curing agents or entire systems, constituting an interesting alternative for a large variety of engineering applications, including the aviation sector. The present work is within the scope of the ECO-COMPASS project, where new bio-sourced epoxy matrixes for green composites are under investigation.

Biaxial tensile experiments are an increasing test alternative of thin‐walled specimens to characterize the material behavior under mechanical agencies. This is mainly driven by digital image correlation systems to obtain information about the surface deformation. However, it is not as simple as a tensile test since we can only measure the deformation in a region on the specimen and not the stress state. The latter aspect of stress determination is discussed as well. In this article, we address several basic questions. First: can we obtain a homogenous strain state in cruciform‐like specimens? In this sense the shape will be discussed and a measure of homogeneity is introduced for proofing whether homogeneity can be guaranteed. Second: how can we reach large strains in the center of the specimens? This is connected to the specimen's geometry (arm reinforcement, slots, thinning of center, …). Furthermore, we discuss the problem of material parameter identification using biaxial tensile test information, which is connected to the concept of identifiability using finite elements. This is discussed at the simplest constitutive model, namely linear isotropic elasticity. Thus, the overall goal is connected to a critical review on biaxial experiments using cruciform specimens. The test materials are polymers.

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Fiber reinforced polymers play a crucial role as enablers of lightweight and high performing structures to increase efficiency in aviation. However, the ever-increasing awareness for the environmental impacts has led to a growing interest in bio-based and recycled ‘eco-composites’ as substitutes for the conventional synthetic constituents. Recently, the international collaboration of Chinese and European partners in the ECO-COMPASS project provided an assessment of different eco-materials and technologies for their potential application in aircraft interior and secondary composite structures. This project summary reports the main findings of the ECO-COMPASS project and gives an outlook to the next steps necessary for introducing eco-composites as an alternative solution to fulfill the CLEAN SKY target.

This work reports the results of an experimental programme aimed at investigating the in-plane behaviour of clay-brick masonry walls externally strengthened by carbon fiber reinforced polymer (CFRP) strips. Particularly, four different geometrical layouts were considered for the CFRP strips, though keeping unchanged the quantity of composites employed in each wall. Firstly, a preliminary experimental work was carried out on samples of the constitutive materials for quantifying their key mechanical properties and evaluating the bond behaviour of FRP strips on the masonry substrates. Then, eleven cyclic shear-compression tests were performed to observe the response of strengthened\ud walls and the influence of the strengthening layouts under investigation. The proposed experimental report is intended as a contribution to the current state of knowledge about the behaviour of FRP-strengthened masonry walls: it is available to assess the accuracy and\ud possibly improve the predictive capacity of design-oriented capacity models. Finally, the comparison of the reported experimental results with the predictions obtained by applying the analytical relationships proposed by a recently issued guideline for FRP strengthening of masonry structures is proposed