The Effect of Accelerated Ageing on Reaction-to-Fire Properties–Composite Materials

As material age, the durability, strength, and other mechanical properties are impacted. The lifespan of a material generally decreases when exposed to weathering conditions such as wind, temperature, humidity, and light. It is important to have knowledge of how materials age and how the material properties are affected. Regarding materials´ fire behaviour and the effect of ageing on these properties, the knowledge is limited. The research questions of the current work are: Are the fire properties of composite materials affected by ageing? And if so, how is it affected? The study is on material at Technology Readiness Level 9 (TRL). In this study, three composite fibre laminates developed for marine applications were exposed to accelerated ageing. Two different ageing conditions were selected, thermal ageing with an increased temperature of 90°C and moisture ageing in a moderately increased temperature of 40°C and a relative humidity of 90%. Samples were collected after one, two and four weeks of ageing. The reaction-to-fire properties after ageing was evaluated using the ISO 5660–1 cone calorimeter and the EN ISO 5659–2 smoke chamber with FTIR gas analysis. The test results showed that the fire behaviour was affected. Two of the composite laminates, both phenolic/basalt composites, showed a deteriorated fire behaviour from the thermal ageing and the third composite laminate, a PFA/glass fibre composite, showed an improved fire behaviour both for thermal and moisture ageing. The smoke toxicity was affected by the accelerated ageing, especially for the PFA/glass fibre composite that showed a higher production of CO and HCN, both for the thermal aged and the moisture aged samples.

The effect of cryogenic machining of S2 glass fibre composite on the hole form and dimensional tolerances

S2 glass fibre reinforced epoxy composites are widely used in aeronautical applications owing to their excellent strength to weight ratio. Drilling glass fibres can be cumbersome due to their abrasive nature and poor thermal conductivity. Moreover, the use of conventional coolants is not desirable due to contamination and additional costs for cleaning the machine part. An alternative is to use environmentally friendly coolants such as liquid nitrogen (LN2) which have been previously employed in machining metals and composites. The current study investigates the effect of drilling S2 glass fibre composite in a bath of LN2. The study aims to evaluate the effect of spindle speed, feed rate and the presence of cryogenic cooling on the form and dimensional tolerances of the hole (hole size, circularity, cylindricity and perpendicularity). Design of experiments and analysis of variance (ANOVA) were used to determine the contribution of the input parameters on the analysed hole quality metrics. Results indicated that drilling S2 glass fibre in a cryogenic bath increased hole size significantly beyond the nominal hole diameter. The hole circularity and cylindricity were reduced compared to holes drilled under dry condition under all cutting parameters due to enhanced thermal stability during the drilling process. The current study aims to provide the scientific and industrial communities with the necessary knowledge on whether cryogenic bath cooling strategy provides better hole quality output compared to dry drilling and other cryogenic cooling strategies which were previously reported in the open literature.

Water Absorption Properties of Kenaf/Glass Reinforced Unsaturated Polyester Composites used in Insulator Rods

Kenaf fibres have acquired enormous attention in recent years, owing to their economic viability and environmental acceptability. Kenaf (natural) fibres have been started to replace the glass fibre (synthetic) in mechanical, electrical applications and have been utilized in several applications of industrial engineering. The current study deals with water absorption of kenaf/glass fibre reinforced unsaturated polyester composite materials used in high voltage polymeric insulator rods. The kenaf/glass hybrid composites were based on 20%, 30% and 40%(by volume) of kenaf fibers replacement glass fibres with modified 60 vol.% unsaturated polyester resins. The composites were immersedin distilled water at room temperature, and composites resistance to water absorption in terms of the rate of water absorption was determined.A considerable difference in the properties of water absorption of the hybrid composite was found demonstrating that the water absorption effect on the characteristics of insulator rods depends on the arrangement and volume fraction of kenaf fibre of the composite used. Based on the results obtained, a slight effect of water absorption on pure glass fibre composite (control) was observed. The addition of kenaf fibre on glass fibre composite rod increased the water absorption of the composite. It was shown that glass fibres surrounding kena ffibre reduced water absorption. Despite the fact that 40 vol.% of kenaf fibre composite had the highest natural fibre content, it showed the lowest water absorption because of its arrangement on all composite diameters, and also because of being surrounded by glass fibres. All of the materials reached equilibrium and ceased to absorb water after 300 hours

Material Model Development of Sandwich Composite: Numerical-Experimental Investigation of Head Dummy Impacting at Vehicle Interior Components

This paper shows the applicability of a non-linear Finite Element (FE) methodology to analyse the elasto-plastic behaviour and the energy absorption of a padding noise-protection material applied to the vehicle interior components. This material is a sandwich built from alternating layers of polymeric foam and of glass fibre composite. The approach considers two design steps. The first one involves the experimental characterization of the material while the latter deals with the assessment of the numerical models validated for a full-vehicle crash analysis.

Damage Detection Performance of the Electromechanical Impedance (EMI) Technique with Various Attachment Methods on Glass Fibre Composite Plates

Composite materials such as glass and carbon fibre composites have become popular and the preferred choice in various applications due to their many advantages such as corrosion resistance, design flexibility, high strength and light weight. Combining materials with different mechanical properties make composites more difficult to evaluate where the damage mechanisms for composites are more complex than traditional materials such as steel. A relatively new non-destructive testing (NDT) method known as the electromechanical impedance (EMI) technique has been studied by various researchers, but the damage detection performance of the method on composite structures still requires more investigations before it can be accepted for field application, especially in aerospace industry due to the high standard of safety. In this paper, the detection capabilities and performance of the EMI technique subjected to different PZT attachment methods have been investigated. To this end, glass fibre composite plates with various attachment methods for the sensor have been prepared and detection of common defects such as delamination and crack with the EMI technique under study has been performed. The performance of each attachment method for identifying different damage types has been analysed and finite element analysis (FEA) was carried out for verification of the experimental results.