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A novel preforming process was developed for non-crimp fabric (NCF) materials that generated in-plane tension through discontinuous blank boundary conditions. The method employed magnetic clamps and was designed to be both flexible and scalable, with clear routes to industrialisation. The capability of the process was explored in physical trials for a hemispherical and a cubic geometry. Characterisation of a biaxial veiled NCF showed the veil had a dominant effect on the bending mechanics. Subsequently a macroscale finite element model was developed to include an efficient bending idealisation and non-orthogonal in-plane material behaviour. Finally, global process optimisation of the preforming process was demonstrated. The optimisation approach used Gaussian process modelling with a periodic kernel to estimate the wrinkle size for untested clamping arrangements and then deployed Bayesian optimisation to find the optimal configuration. Results indicated that distributed magnetic clamping was effective and amenable to surrogate modelling.

Hydrogen storage by adsorption offers operational benefits over energy intensive compression techniques. Incorporating physisorption materials in compression stores could improve hydrogen capacities, reducing the volume or pressure needed for storage vessels. However, such materials are often presented as fine powders and development efforts to date have predominantly focused on improving hydrogen uptake alone. Without due attention to industry-relevant attributes, such as handling, processability, and mechanical properties it is unlikely that these materials will find commercial application. In the paper, the desirable mechanical properties of hydrogen-adsorbent PIM-1 are exploited to yield a series of composite monoliths doped with a high surface area activated carbon, intended to act as pressure vessel inserts. Freeze casting techniques were successfully adapted for use with chloroform, facilitating the production of coherent and controlled three-dimensional geometries. This included the use of an innovative elastomeric mould made by additive manufacture to allow facile adoption, with the ability to vary multiple forming factors in the future. The composite monolith formed exhibited a stiffness of 0.26 GPa, a compressive strength of 6.7 MPa, and an increased BET surface area of 847 m2 g−1 compared to PIM-1 powders, signifying the first steps towards producing hydrogen adsorbents in truly useful monolithic forms.

A major barrier to high-rate manufacture of non-crimp fabric (NCF) preforms is the relatively low volume of research evaluating multiple ply forming strategies. This study presents an extension to the distributed magnetic clamping (DIMAC) method towards establishing flexible process control measures for multiple ply forming. A measure of wrinkling was devised to allow comparison across different stack thicknesses and the distributions of wrinkles were shown to correlate with process parameters in an experimental parametric study. Further, ply-bending mechanics were shown to have a dominant effect on the draw-in of compression folds, particularly when increasing the number of equivalent biaxial plies. However, by deploying targeted distributed clamps, three-ply, single-stroke strategies over a complex positive curvature geometry became viable. DIMAC is shown to facilitate the local adjustment of boundary conditions whilst offering flexibility in improving component quality.

Discrete Stiffness Tailoring (DST) is a novel manufacturing concept where stiffness tailoring is achieved using discrete changes in ply angle to favourably redistribute stresses. Resulting performance increases can be exploited to potentially achieve lightweight rapidly manufacturable structures, uninhibited by the minimum tow-turning radii which limit continuous fibre steering approaches. An efficient two-stage optimisation routine is implemented to design a DST minimum-mass stiffened aircraft wing panel subject to buckling and manufacturing feasibility constraints. The panel is manufactured and compression tested to failure, extending the DST design concept to component level for the first time. A weight reduction of 14.4% is achieved compared to a constant stiffness optimum, through redistribution of load to the stiffener region. The optimum design removes material from the skin, between stiffeners. Experimentally, the optimised tailored panel achieved a buckling load, without failure, within 5% of that predicted, validating both the methodology and modelling.

Forming of composite materials is more challenging than forming of conventional materials, such as metals, because their complexity often renders predictive modelling intractable. However, relying on experiments and rigid tooling is also time-consuming, costly and provides limited scope. Conversely, faster production speeds require processes that can be applied to a range of geometries while maintaining control to reduce forming defects. In recent literature, the positive influence of clamping along the periphery of a blank has been established, notably in preventing wrinkling. In this work, we propose a method for facilitating the creation of challenging geometries by changing the boundary conditions in a flexible manner. This method allows for direct adjustment of local stress conditions and can be automated and optimised for a diverse range of part geometries. We present a purpose-built rig to test this concept and preliminary results confirming its efficacy.