Experimental and numerical investigation of the shear behaviour of infiltrated woven fabrics (original) (raw)
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Composites Part A: Applied Science and Manufacturing, 2019
Wet compression moulding (WCM) provides high-volume production potential for continuous fibre-reinforced composite components via simultaneous draping and infiltration. Experimental and theoretical investigations proved strong mutual dependencies between resin flow and fabric deformation, which are not fully understood yet. This limits development of suitable process simulation methods and applies in particular for the characterisation of infiltrated bending behaviour-essential for an accurate prediction of draping effects. Therefore, a comparative characterisation of the bending behaviour of dry and infiltrated woven fabrics is presented using a modified cantilever and a rheometer bending test. Experimental results reveal both, rate-and viscosity-dependencies. A comparison of the quantitative results exposed an explicable systematic deviation between the two tests, whereas qualitative results are comparable. Finally, Finite Element forming simulations, comprising two bending models corresponding to cantilever and rheometer test are performed to evaluate the experimental findings on component level.
Key Engineering Materials, 2019
The wet compression molding (WCM) process enables short cycle times for production of fiber-reinforced plastics due to simultaneous infiltration, viscous draping and consolidation in one process step. This requires a comprehensive knowledge of occurring mutual dependencies in particular for the development of process simulation methods and for process optimization. In this context, it is necessary to develop suitable test benches to enable an evaluation of the outlined viscous draping behavior. In order to evaluate and suitably design the draping process, grippers are mounted on a surrounding frame, which enables targeted restraining of the local material draw-in during forming. In supporting the development of the new test bench, first experimental and simulation results are compared, which thereby enables a first validation of the simulation approaches. Results show a good agreement between experimental and numerical results in terms of shear deformation and final gripper displace...
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Forming of continuously fibre-reinforced polymers (CoFRP) has a significant impact on the structural performance of composite components, underlining the importance of forming simulation for CoFRP product development processes. For an integrated development of industrial composite components, efficient forming simulation methods are in high demand. Application-oriented method development is particularly crucial for industrial needs, where large and complex multi-layer components are manufactured, commercial FE software is used, and yet high prediction accuracy is required. To meet industrial demands, this contribution gives an insight in macroscopic forming simulation approaches that utilize the FE software ABAQUS in combination with user-defined material models and finite elements. Three CoFRP forming technologies are considered, which are in industrial focus due to their suitability for mass production: textile forming of dry unidirectional non-crimp fabrics (UD-NCF), thermoforming of pre-impregnated UD tapes and wet compression moulding (WCM). In addition to the highly anisotropic, largestrain material behaviour that composite forming processes have in common, the three process technologies face various process-specific modelling challenges. UD-NCFs require material models that capture the deformation behaviour and the slippage of the stitching. Thermoforming of UD tapes is highly rate-and temperature-dependent, calling for rheological membrane and bending modelling. Moreover, a thermomechanical approach including crystallisation kinetics enables the prediction of potential phase-transition during forming and resulting defects in the semicrystalline thermoplastic matrix. For simultaneous forming and infiltration in wet compression moulding, a finite Darcy-Progression-Element is superimposed with the membrane and shell elements for forming simulation, capturing infiltration-dependent material properties. The three outlined technologies illustrate the complexity and importance of further simulation method development to support future process development.
Investigating the shear behaviour of high-performance fabrics
Investigating the shear behaviour of high-performance fabrics, 2023
Shear modulus is a critical factor that significantly influences the mechanical properties and overall performance of these textiles. Understanding the mechanics behind fabric performance during forming operations is of paramount importance, especially given the diverse use of various fabric types as key components in composite products. Fabric's ability to undergo shear deformation is a pivotal attribute in forming and facilitating the transformation of 2-dimensional preforms into intricate 3-dimensional structures. In numerous industrial applications, the manufacturing of composite materials heavily relies on carbon and Kevlar fibers. This research investigates the relationship between shear stress and wrinkling in single-layer structures. The investigation involved woven fabrics composed of carbon, Kevlar, and hybrid carbon-Kevlar configurations. The study encompassed an assessment of shear characteristics, wrinkling force, and fabric stiffness for each fabric variant. To comprehensively analyze the intricate interplay among in-plane shear characteristics, fabric parameters, and tow properties in the scope of shear behavior, the study's findings underwent meticulous scrutiny. Selected tow and fabric parameters exhibit a substantial paired association with the fabric shear modulus, a deduction derived from analysis of experimental results. The formulated fabric shear index serves as a valuable tool for categorizing the fabric's response to shear forces. The shear force component that triggers the onset of buckling demonstrates a proportional relationship with the cube root of the fabric shear modulus. This observation sheds light
In-plane Shear Behaviour of Novel Thick Stitched Textile Reinforcements Part I: Experimental Work
AL-MUKHTAR JOURNAL OF ENGINEERING RESEARCH, 2021
Novel thick, net-shape, drapable, high fibre volume fraction (vf) textile reinforcements used toward manufacturing aerospace polymer matrix composites (PMCs) are being developed at the University of Ottawa. The technology, referred to in this paper as University of Ottawa advanced preforming technology (uO-APT), it enables the manufacturing of flat, drapable multilayered near net-shape preforms. The in-plane shear behaviour of such novel thick reinforcement textiles was investigated to understand and define the behaviour of such thick fabric reinforcements when formed into required shapes. Wrinkling is one of the most common and critical defects that may occur during draping and forming operations performed on textile reinforcements. The behaviour of dry thick fabrics subjected to in-plane shear plays an important role, along with the bending behaviour, in the onset of wrinkles during draping and forming. Wrinkling is especially critical to single layer, thick fabrics such as uO-APT fabrics being investigated in this paper. Since the ability of biaxial stitched non-crimp reinforcement fabrics to conform to a surface featuring double curvatures depends directly on their inplane shear behaviour, that behaviour must be probed and quantified for uO-APT fabrics in order to identify their ability to deform upon draping, which is a required procedure in manufacturing processes for dry preforms used towards the production of composite parts.