Mechanical properties of carbon fibre reinforced composites modified with star-shaped butyl methacrylate

This article presents the possibility of strength improvement and energy absorption of carbon fibre reinforced polymer composites by matrix modification. In this study, the mechanical properties of bisphenol-A epoxy matrix and carbon fibre reinforced polymer composites were modified with four different wt.% of star-shaped polymer n-butyl methacrylate (P n-BMA) block glycidyl methacrylate (PGMA). The tensile strength of the epoxy with 1 wt.% star-shaped polymer showed 128% increase in comparison to unmodified epoxy samples. Two different wt.% were then used for the modification of carbon fibre-reinforced polymer composite samples. Tensile tests and low-velocity impact tests were conducted for characterising modified samples. Tensile test results performed showed a slight improvement in the tensile strength and modulus of the composite. Low-velocity impact tests showed that addition of 1 wt.% star-shaped polymer additives increase composite energy absorption by 53.85%, compared to pure epoxy composite specimens. Scanning electron microscopy (SEM) analysis of post-impact specimens displays fracture modes and bonding between the matrix and fibre in the composites. These results demonstrate the potential of a novel star-shaped polymer as an additive material for automotive composite parts, where energy absorption is significant.

Thermal Qualification of the UHTCMCs Produced Using RF-CVI Technique with VMK Facility at DLR

Ultra high-temperature ceramic matrix composites (UHTCMCs) based on carbon fibre (Cf) have been shown to offer excellent temperature stability exceeding 2000 °C in highly corrosive environments, which are prime requirements for various aerospace applications. In C3Harme, a recent European Union-funded Horizon 2020 project, an experimental campaign has been carried out to assess and screen a range of UHTCMC materials for near-zero ablation rocket nozzle and thermal protection systems. Samples with ZrB2-impregnated pyrolytic carbon matrices and 2.5D woven continuous carbon fibre preforms, produced by slurry impregnation and radio frequency aided chemical vapour infiltration (RF-CVI), were tested using the vertical free jet facility at DLR, Cologne using solid propellants. When compared to standard CVI, RFCVI accelerates pyrolytic carbon densification, resulting in a much shorter manufacturing time. The samples survived the initial thermal shock and subsequent surface temperatures of >2000 °C with a minimal ablation rate. Post-test characterisation revealed a correlation between surface temperature and an accelerated catalytic activity, which lead to an understanding of the crucial role of preserving the bulk of the sample.

Development and Mechanical Testing of Carbon Fiber Reinforced Polymer Matrix Composites for Micro Wind Turbine Applications

In this century, composites have been discovered to be the most promising and discriminating material accessible. Composites reinforced with synthetic or natural fibres are becoming more popular as demand for light weight, high strength materials for specialized applications grows are on the rise in the market. In the current work Carbon fiber Reinforced Polymer Matrix Composite material is developed aiming wind turbine blade applications. This research demonstrates the successful development of a carbon fibre reinforced Epoxy matrix composite that can be utilized to make micro wind turbine blades and is very cost effective thanks to the utilization of a simple hand lay-up approach. The peak elongation varies from 12.248 mm to 14.417 mm, and the tensile strength varies from 939.472 N/mm2 to 960.910 N/mm2. It was observed that the Compressive Strength varies from 8.992 N/mm2 to 46.895 N/ mm2 and peak elongation varies from 1.808 mm to 3.462 mm. In three-point bending test, the peak load was found to be 509.96 N. Due to the presence of carbon fibre reinforcement, the bending strength of polyester resin has been greatly increased.

Fibre alignment and mechanical performance of carbon fibre Sheet Moulding Compounds under different preform compaction

This work investigates the effect of preform compaction on the mechanical performance and flow-induced fibre alignment of carbon fibre reinforced Sheet Moulding Compounds (SMCs). Two groups of panels have been compression moulded from reclaimed carbon fibre tows in vinyl-ester resin with low (0.5 MPa) and high (10 MPa) preform compaction pressure Additionally, a low-cost fibre orientation analysis method has been further improved in terms of reliability, and a novel flow assessment method has been developed for carbon fibre SMCs. This approach revealed greater fibre alignment with the flow direction in the lower faces of panels as a result of greater contact time with the heated mould and a lower charge viscosity at the time of pressing. As expected, greater fibre alignment in the flow direction was observed outside the initial charge coverage area in both types of panels, where the flow was greatest. Due to additional fibre flow during the high-pressure compaction stage, the mean degree of flow alignment in the high compaction panel was 47% higher than that of the low compaction panel. Improvements in the tensile stiffness (8%) and strength (32%) were also observed as a result of the high-pressure compaction stage and associated flow alignment.

FEM-Validated Optimal Design of Laminate Process Parameters Based on Improved Genetic Algorithm

In tape placement process, the laying angle and laying sequence of laminates have proven their significant effects on the mechanical properties of carbon fibre reinforced composite material, specifically, laminates. In order to optimise these process parameters, an optimisation algorithm is developed based on the principles of genetic algorithms for improving the precision of traditional genetic algorithms and resolving the premature phenomenon in the optimisation process. Taking multi-layer symmetrically laid carbon fibre laminates as the research object, this algorithm adopts binary coding to conduct the optimisation of process parameters and mechanical analysis with the laying angle as the design variable and the strength ratio R as the response variable. A case study was conducted and its results were validated by the finite element analyses. The results show that the stresses before and after optimisation are 116.0 MPa and 100.9 MPa, respectively, with a decrease of strength ratio by 13.02%. The results comparison indicates that, in the iterative process, the search range is reduced by determining the code and location of important genes, thereby reducing the computational workload by 21.03% in terms of time consumed. Through multiple calculations, it validates that “gene mutation” is an indispensable part of the genetic algorithm in the iterative process.