Abstract:Natural fibres are studied as alternatives for man-made fibres to reinforce composites while keeping the weight lower. The assessment of the value of some commonly available tropical fibres for the composite industry starts with the determination of the strength, E-modulus and strain to failure through single fibre tensile tests. The mean strength and standard deviation is calculated following the normal and Weibull distribution resulting in the questionable benefit of applying the Weibull distribution. Furthermore, a correction method assesses the real fibre elongation from the measured clamp displacement. This procedure seems to be useful for strong, brittle fibres to produce more reliable results for the E-modulus and strain to failure.

decade, substantial efforts were devoted to the research and development of the nextgeneration composites. This new class of materials should not only possess higher strength-to-weight ratio than metals but also tailored with integrated intelligence, which is desirable as infrastructures for next generation of "internet of things." Carbon nanomaterials, such as carbon nanotubes and carbon nanofibers, have received dominant attention for the creation of intelligent composites. [3][4][5][6] They were dispersed in a polymer matrix to form conductive percolating networks as distributed sensors in situ to evaluate the strain, stress, damage, and temperature for self-sensing and on-line structural health monitoring applications. [3][4][5][6] However, these composites are restricted to (piezo) resistive effect based sensing capabilities from the included nanomaterials. Nextgeneration composites, however, should not only encompass sensing capabilities but also be equipped with other functionalities such as lighting, computation, and communication elements, as illustrated in Figure 1. One straightforward solution to achieve this goal is to integrate electronic circuits with off-the-shelf components in the composites. However, these functional composites usually have complex, 3D shapes, but conventional electronic circuits are rigid and planar. The shape mismatch between 3D composites and planar, rigid electronic circuits causes difficulties in integrating electronic circuit-based intelligences.Recent advancement of flexible and stretchable circuits has paved the way for integration of electronics in unusual shapes and forms. Through materials and structure innovation, [7] the circuits become stretchable, deformable, and conformable to curvilinear surfaces, [8][9][10] enabling a spectrum of applications such as stretchable sensors and actuators, [11][12][13][14] transparent conductors, [15,16] lighting, [17][18][19] and energy devices. [20][21][22] Various types of stretchable nanomaterials, such as carbon nanomaterials [23][24][25] and metal nanowires [26][27][28] have been synthesized and integrated to elastomeric polymer matrix for stretchable circuits. Despite their superior mechanical properties and potential to achieve transparent stretchable circuits, so far it has been a struggle to deliver high enough conductivities compared to structure engineered stretchable circuits.Fiber-reinforced polymer composites with integrated intelligence, such as sensors, actuators, and communication capabilities, are desirable as infrastructures for the next generation of "internet of things." However, the shape mismatch between the 3D composites and a planar electronic circuit causes difficulties in integrating electronic circuit-based intelligences. Here, an easily scalable approach, by incorporating a large-area stretchable circuit with thermoforming technology, to fabricate 3D multifunctional composites is reported. The stretchable circuit is first fabricated on a rigid and planar carrier board, then transferred and sandwiched bet...

Combining stretchable circuits and thermoforming technology, a method to produce 3D multifunctional polymer composites is described by Yang Yang, Jan Vanfleteren, and co‐workers in article number https://doi.org/10.1002/aelm.201800071. A demonstrator consisting of a seven‐segment display with integrated LEDs and capacitive touch sensors is fabricated using the proposed method. The cover image was designed and illustrated by Xiao‐Meng Wu and Dong Tao.

No abstract

No abstract