Progressive damage modeling of open-hole composite laminates under compression

Composite Structures122507-51

Geometrically nonlinear analysis of matrix cracking and delamination in composites with floating node method

In this paper, the recently-developed floating node method is extended for damage analysis of laminated composites with large deformations. Strong discontinuities including interfacial delamination and matrix cracks are explicitly represented by geometrically nonlinear kinematics. Interactions between these two kinds of failure patterns are enabled through enriched elements equipped with floating nodes. A cohesive zone model is utilized for the damage process zone. A general implicit procedure with user-defined elements is developed for both quasi-static and dynamic analysis. The performance of this formulation is verified with two benchmark simulations, involving buckling-induced delamination and low-velocity impact damage. The results presented show good quantitative and qualitative agreements with results from literature.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Aerospace Structures & Computational Mechanic

Direct FE2 for simulating strain-rate dependent compressive failure of cylindrical CFRP

In this study, the strain-rate dependent compressive failure of cylindrical carbon fiber reinforced plastics (CFRP) is simulated by using Direct FE2. The Direct FE2 method can reduce the computational cost compared with conventional FE2 multiscale simulation. It can be implemented with commercial FE code, without the complicated coding usually required for conventional FE2. At the microscale level, the true dimension of the individual fibers, failure of the fiber/matrix interface, and the strain-rate dependence of failure strength of the matrix material are modeled. These microscale characteristics are used to directly model the macroscale strain-rate dependent failure of a cylindrical CFRP specimen subjected to the Split Hopkinson Pressure Bar (SHPB) test. The obtained FE2 numerical results are in good agreement with the experimental results

Prototyping and testing of composite riser joints for deepwater application

The high strength to weight ratio, good corrosion resistance, and excellent fatigue property make carbon fiber-reinforced plastics a competitive material solution to replace steel in deepwater riser application. In this work, scaled-down composite riser joints were fabricated using a filament-winding machine. The prototypes comprise several carbon fiber-reinforced plastic layers wound over an aluminum liner. They consist of a middle tubular section and two metal-composite interface end fittings for the transfer of load between joints. A series of mechanical tests, including tension and combined tension-bending loading tests were performed to characterize their structural capacity and evaluate the improvement in performance over a purely metallic mandrel. In addition, finite element analyses incorporating elastic–plastic properties of the metallic liner, interfacial failure, and complex carbon fiber-reinforced plastics failure modes were carried out. The numerical predictions are in good agreement with the experimental measurements. The experimentally verified FE framework was then extended to design and analyze a full-scale composite riser model for performance prediction to accelerate the application of composite risers by shortening product development cycle and reducing prototyping costs

Modeling delamination migration in cross-ply tape laminates

Composites Part A: Applied Science and Manufacturing71192-20

Lightweight, Fiber-Damage-Resistant, and Healable Bio-Inspired Glass-Fiber Reinforced Polymer Laminate

Glass-Fiber-Reinforced Polymer (GFRP) laminates are widely used in the automotive and marine industries such as auto bodies and boat hulls. Decreasing the weight and improving the reparability of GFRP parts will cut down material usage, fuel consumption and repair costs. This study shows a bio-inspired helicoidal stacking configuration that significantly improves the impact performance and fiber damage resistance of GFRP laminates. For similar impact performance in terms of perforation energy, the helicoidal GFRP laminate is 20% lighter than the conventional quasi-isotropic GFRP laminate. Upon impact, delaminations and matrix splits link-up and grow extensively throughout the helicoidal laminate. This effectively reduces fiber damage and improves impact performance. Because helicoidal GFRP laminates are resistant to fiber damage and composite healing agents can effectively repair non-fiber damage, embedding healing agents into helicoidal GFRP results in lightweight, inexpensive and healable laminates

Revealing Chemical Heterogeneity of CNT Fiber Nanocomposites via Nanoscale Chemical Imaging

Lightweight nanocomposites reinforced with carbon nanotube (CNT) assemblies raise the prospects for a range of high-tech engineering applications. However, a correlation between their heterogeneous chemical structure and spatial organization of nanotubes should be clearly understood to maximize their performance. Here, we implement the advanced imaging capabilities of atomic force microscopy combined with near-field infrared spectroscopy (AFM-IR) to analyze the intricate chemical structure of CNT fiber-reinforced thermoset nanocomposites. As an example, we unravel the chemical composition of a nanothin polymer interphase exclusively from CNT assemblies and visualize in a two- and three-dimensional format with resolution of sub-30 nm. We furthermore introduce a contact frequency map colocalized with CNTs and surrounding polymer, which might correlate the local mechanical properties with polymer chemistry and the high anisotropy of CNTs. Nanoresolved chemical imaging offers possibilities for in-depth characterization of next-generation composite materials and devices based on CNT assemblies interacting with a certain chemical environment