A review of input data and modelling assumptions in longitudinal strength models for unidirectional fibre-reinforced composites

Abstract

Fibre-reinforced composites are rapidly increasing their market share in structural applications. Nevertheless, this increase would be much stronger if reliable failure predictions were available. These predictions are not only insufficiently reliable for complex loading of multidirectional composites, but even for longitudinal tensile failure of unidirectional (UD) composites. Since composite failure usually coincides with longitudinal failure of a 0° ply, the reliability often hinges on longitudinal failure predictions of UD composites. Despite great progress in the state-of-the-art models, significant obstacles remain in collecting the necessary input data and understanding the influence of the modelling assumptions. This review therefore surveys the mechanics, chemistry and physics involved in tensile failure of UD composites and highlights potential areas for improvement. Specific proposals are made to advance the state-of-the-art strength models, which could catalyse the use of composites in structural applications.

Stress redistribution around clusters of broken fibres in a composite

“…While interfacial debonding is often observed in single fibre fragmentation tests, there is no evidence of debonding occurring in composites with thousands or millions of 125 fibres [2]. In addition, recent x-ray tomography images [21,25] suggest that debonding may not occur during the formation of clusters; in fact, the prevalence of planar clusters appear to be incompatible with the formation of splits after each fibre breaks.…”

“…Longitudinal tensile failure of composites is a complex process governed by: (i) variations in strength between each fibre and (ii) the stress redistribution that occurs around broken fibres [1,2]. While strength variations can be quantified using single fibre tensile tests, insights on stress redistribution rely essentially on modelling efforts.…”

“…In 155 the literature, the matrix has been modelled with a variety of constitutive behaviours such as linear elastic [12,17,19,25], non-linear elastic [10], linear elastic perfectly-plastic [13,14,18] or linear elastic with linear strain hardening [38]. Results indicate that for the options enumerated above, matrix plasticity has a reduced effect on the stress concentration factor, but leads to longer recovery lengths [2]. However, our knowledge of the matrix behaviour is based 160 on pure tension, compression or shear tests done on bulk epoxy, and these experiments are unlikely to be representative of in situ conditions where a high stress triaxiality is present and high strain-rates may occur following a fibre break.…”

Structure and Properties of Polysulfone Filled with Modified Twill Weave Carbon Fabrics

“…Continuous CF reinforced unidirectional composites are popular objects for modeling and theoretical approaches [20,21]. Unidirectional composites allow for the realization of CF mechanical characteristics better than 2D ones [1].…”

Pengaruh Orientasi Serat Kaca Terhadap Kekuatan Impact Pada Bodi Prototipe Mobil Listrik

“…Penggunaan material komposit di era ini sangatlah luas di berbagai apliksi teknik, seperti barang-.barang luar angkasa, transportasi laut, dan otomotif, karena komposit memiliki sifat mekanik yang luar biasa, dari segi hubungan antara kekuatan terhadap berat, kekakuan terhadap berat, fomability, dan toleransi kerusakan [2]. Jika dibandingkan dengan material isotropic yang lain, pendekatan prediksi kegagalan material pada komposit bisa dikatakan tidak mudah, hal tersebut dikarenakan beberapa ketidakpastian mengenai hubungan antara geometri mikrostruktur dan sifat mekaniknya [3][4][5]. Pada kemampuan pembebanan material komposit, ditemukan nilai yang bersifat acak, hal ini disebabkan oleh kompleksitas material akibat sifat anisotropi,sifat heterogen, dan deposit cacat selama proses manufaktur [6,7].…”