This study investigates the effect of embedded circular defects with varying sizes and locations on the compressive properties of twill-woven carbon fiber reinforced composites. Composite laminates with dimensions of 150 mm × 100 mm × 4 mm were fabricated using the prepreg stacking and hot-press curing. Circular defects with diameters ranging from Φ 10 mm to Φ 50 mm were introduced at different through-thickness locations, including single (1/2, 1/4) and combined locations (e.g., 1/2 1/4, 1/2 1/4 1/8). To predict the compressive strength and modulus under complex defect conditions, an artificial neural network (ANN) model was developed using four input features: defect diameter and multi-label binary spatial encoding defect location. The ANN model achieved high prediction accuracy with a coefficient of determination (R2) exceeding 0.94 on the strictly withheld independent test set evaluating single-plane defect scale interpolation, demonstrating its capability to capture the non-linear relationship between embedded damage characteristics and mechanical response. Results indicate that both defect size and location significantly influence compressive performance, and the combined presence of multiple defects introduces non-additive degradation effects. This work provides a practical data-driven framework for evaluating the residual compressive performance of twill-woven CFRP laminates within the verified material and geometric boundary envelopes.
The consequences of long-term immersion in a natural marine environment of unidirectional flax / PolyPropylene + Maleic Anhydride grafted PolyPropylene (PP + MAPP) composites were compared with those of ageing in deionized water containing a biocide in laboratory conditions (20 °C and 40 °C). The mechanical properties under tensile loading, microstructure evolution and mass and density variation were studied over time. The drop in the mechanical properties of samples immersed in seawater is much greater than that of samples aged in the laboratory with biocide. This difference is consistent with degradation of the flax fibers potentially associated with biological colonization by fungi and bacteria. SEM observations confirmed the presence of biological colonization within the biocomposites, but the relative contributions of abiotic and biotic processes were not quantified in this study. Therefore, natural seawater ageing tests should consider both abiotic and biotic mechanisms to accurately describe the overall degradation processes occurring during the biocomposite lifetime. The mechanisms observed highlight the need to reassess protocols for accelerated ageing tests and to develop complementary experiments to determine the contributions of both biological and non‑biological factors.
Lattice structures have great potential for lightweight load-bearing and energy absorption applications, but sharp-cornered nodes in traditional composite lattices can cause abrupt changes in fiber paths and local manufacturing defects. To address this issue, this study proposes a symmetric double-corrugated lattice design strategy. Using TCL as the control, three corrugated lattices, namely SCL, CCL and PCL, are designed and manufactured through a modular orthogonal assembly method. Micro-defect characterization, quasi-static crushing tests and finite element simulations were combined to investigate the effects of corrugation geometry on manufacturing quality, crushing response, energy absorption and failure modes. The results show that the symmetric double-corrugated design improves fiber-path conformity, reduces defect concentration near sharp-cornered nodes and promotes a transition from localized failure to progressive crushing. Compared with TCL, SCL increases the average crushing load, specific energy absorption, and crushing force efficiency by 16.47
Carbon fiber reinforced polymer (CFRP) composites are in increasing demand in critical applications, yet the standard manufacturing methodology, autoclave curing, remains costly and energy intensive. Microwave curing offers an out-of-autoclave (OOA) solution to this limitation, but many existing systems rely on similarly expensive and large multi-mode systems. In this work, 16-layer unidirectional Cycom 5320-1 prepreg laminates, with 2.5 mm thickness, are analyzed to study their behavior as they are heated and cured in a domestic microwave modified with a custom mode stirring mechanism. A Multiphysics finite element (FE) model is created to predict the complex coupled electromagnetic, thermal, and curing physics using COMSOL Multiphysics software. The model successfully reproduced the fiber orientation dependent temperature differentials observed experimentally by loading the composites one at a time into the microwave with the fibers oriented parallel and perpendicular to the dominant field direction, confirming that fiber-field coupling persists in single magnetron systems despite the presence of mode stirring. The differences in power required to cure the two panels are quantified along with the maximum temperature differences that the panels experience through their thickness and across the surface. Variation in the resulting degree of cure across the part is also reported using a modified Arrhenius equation. A parametric study on the location of the mode stirrer within the microwave cavity is performed to optimize its placement for curing uniformity. Deposited power is shown to depend on fiber orientation relative to the cavity field polarization. The predicted ratio of deposited power between orientations agrees with measured magnetron power requirements to within 6.4
Lightweight textile protection depends on recruiting sufficient yarn length before local damage interrupts load transfer. Through-thickness binder yarns provide an architectural means of coordinating that recruitment across woven layers. Their effects are often discussed through weave labels or isolated performance gains, which obscure the variables responsible for the response. This review organizes ballistic evidence around binder path, binding depth, interlacing frequency, binder content, and hybrid configurations. Experimental comparisons are linked to their material state, areal density, projectile, and boundary conditions; numerical methods are assessed against the binder phenomena they resolve. The synthesis identifies the competition between interlayer constraint and yarn mobility as a useful basis for interpreting architecture-dependent performance. Binder yarns redirect contact forces and deformation in dry fabrics, while resin-impregnated systems additionally involve matrix damage and crack bridging. Reported benefits of deeper and hybrid binding illustrate how this competition can be exploited within specific configurations. A three-region framework expresses these competing mechanisms without prescribing a universal optimum binder fraction. The review also distinguishes projectile kinetic-energy loss from irreversible dissipation and separates global model agreement from validation of local damage timing. Together, these connections provide a practical basis for selecting binder architectures, interpreting ballistic comparisons, and directing geometry-based and data-driven design toward measurable protection objectives.
