Size effect in flexural behaviour of unidirectional GFRP composites

Abstract

In this paper, the size effect in unidirectional (UD) laminated glass-fibre reinforced plastic (GFRP) composites subjected to quasi-static bending loading was investigated: the sensitivity of a specimen's mechanical behaviour and failure mechanism to its geometry was studied. Composite beams with different numbers of 0° unidirectional plies were tested and their post-deformation structures were analysed microscopically. In the subsequent simulations, the intraply damage was modelled using continuum damage mechanics, implemented as a user-defined VUMAT subroutine in ABAQUS/Explicit, while cohesive zone elements were employed to characterize the delamination between different plies. It was observed that the flexural failure triggered the multiple delaminations; their location was studied. The influence of the size effect on the bending response of the UD composite beams was analysed in depth. The findings of the current study can be used to design modern structures made of composite materials.

Features of Three-Point Bending Tests for Determining Out-of-Plane Shear Modulus of Layered Composites

“…At the same time, the possibility of the thickness increasing is limited since the low span-to-thickness ratio leads to the invalidity of Timoshenko beam scheme because the specimen behaves like a plate in this case [17]. Moreover, the thickness increasing leads to the possible appearance of scale effect [4][5][6][7][8][9]. All these factors can lead to potential errors that are difficult to assess.…”

“…Their joint assessment is mandatory under bending testing of beam specimens made of anisotropic materials. When choosing the specimen dimensions, it is necessary to take into account that their thickness has a strong effect on the deflections due to the scale effect [4][5][6][7][8][9]. In [9], an impact of the thickness was studied by comparing the bending deformation curves for the specimens of unidirectional composites.…”

Особенности Испытаний На Трехточечный Изгиб Для Определения Межслойного Модуля Сдвига Слоистых Композитов

“…Для увеличения вклада сдвигов в общее перемещение возможно использование более толстых образцов [10]. Однако увеличение толщины приводит к возникновению масштабного эффекта, способного влиять на конечные свойства компози- тов [4][5][6][7][8][9]. В то же время возможность увеличения толщины ограничена, поскольку перестает работать балочная схема Тимошенко, и формулы обработки испытаний на изгиб становятся неправомерны [17].…”

“…Их совместная оценка обязательна при испытаниях на изгиб балок из анизотропных материалов. При выборе размеров балок необходимо иметь в виду, что вследствие масштабного эффекта толщина влияет на прогиб при изгибе [4][5][6][7][8][9]. В работе [9] ОСОБЕННОСТИ ИСПЫТАНИЙ НА ТРЕХТОЧЕЧНЫЙ ИЗГИБ ДЛЯ ОПРЕДЕЛЕНИЯ... влияние толщины изучали путем сравнения кривых деформирования при изгибе однонаправленных композитов четырех разных толщин.…”

Research on Low-Velocity Impact Response of Novel Short-Fiber-Reinforced Composite Laminates

“…When the failure criterion is reached in some area of the composite, the damage begins to occur, and visible or invisible cracks begin to expand, resulting in stiffness degradation and gradually reducing load capacity. Due to the correlation with mechanical parameters, the method based on fracture energy is widely used to predict the progressive damage behavior of composites, such as the equivalent displacement method, which has been well verified by a large number of experimental results [ 20 , 21 , 22 ]. In the main damage types that occur in laminates, delamination is viewed as the crucial one because it might drastically decrease the compression strength, stability and integrity of composites [ 23 ].…”