This study investigated the dynamic mechanical properties of hybrid intraply carbon/E‐glass epoxy composites with different orientations and stacking sequences under different loading conditions with increasing temperature. A neat epoxy and five various hybrid composites such as Carbon (0°)/E‐glass (90°), Carbon (45°)/E‐glass (135°), Carbon (90°)/E‐glass (0°), Carbon/E‐glass (alternating layer), and Carbon/E‐glass (alternating layer 45°) were manufactured. Three‐point bending test and dynamic mechanical test were conducted to understand the flexural modulus and viscoelastic behavior (storage modulus, loss modulus, and loss tangent) of the composites. Dynamic mechanical test was performed with the dual cantilever method, at four different frequencies (1, 5, 10, and 20 Hz) and temperatures ranging from 30 to 150°C. The experimental results of storage modulus, loss modulus, and loss tangents were compared with the theoretical findings of neat epoxy and various hybrid composites. The glass transition temperature (Tg) increased with the increase in frequency. A linear fit of the natural log of frequency to the inverse of absolute temperature was plotted in the activation energy estimation. The interphase damping (tanδi) between plies and the strength indicator (Si) of the hybrid composites were estimated. It was observed that the neat epoxy had more insufficient storage and loss modulus and a high loss tangent at all the frequencies whereas hybrid composites had high storage and loss modulus and a low loss tangent for all the frequencies. Compared with other hybrid composites, Carbon (90°)/E‐glass (0°) had higher strength and activation energy. The result of reinforcement of hybrid fiber in neat epoxy significantly increases the material's strength and stability at higher temperatures whereas decreasing free molecular movement.

This work investigated the thermo‐mechanical behavior of (carbon/Kevlar) intraply hybrid composites. The carbon/Kevlar plies' orientation and sequential arrangement were varied. Carbon and Kevlar composites, as well as five different intraply hybrids (HFRPs) composite such as carbon‐0°/Kevlar‐90°, carbon‐45°/Kevlar‐135°, carbon‐90°/Kevlar‐0°, carbon/Kevlar (inter‐changing layer), and carbon/Kevlar‐45° (inter‐changing layer) composites, and a plain epoxy panel, have been developed. The thermo‐mechanical characteristics of the fabricated composites were estimated using a dynamic automated analyzer under changing mechanical and thermal load conditions. The DMA technique measured the HFRPs composite visco‐elastic parameters by increasing the temperature from 30°C to 150°C at frequencies ranging from 1 to 20 Hz. Flexural test characteristics for neat epoxy, carbon fiber‐reinforced composites, Kevlar fiber‐reinforced composites, and carbon/Kevlar fiber‐reinforced composites were estimated to aid the study. The experimentally measured versus analytically calculated viscoelastic parameters were related. The results revealed that carbon‐90° oriented in warp direction/Kevlar‐0° oriented in weft direction exhibited higher modulus and lower loss tangent followed by carbon/Kevlar plies oriented in alternate layers and carbon/Kevlar plies oriented in inter‐changing layers at 45°. Carbon‐0° introduced in the weft direction/ Kevlar‐90° introduced in the warp direction, and carbon‐45°/Kevlar‐135° exhibited intermediate storage and loss modulus and a moderate loss tangent at the various frequency levels considered in the study.

Emissions coming out from the automobile accounts for significant universal carbon emission. The reduction in the weight of the vehicle even by a kilogram can lead to a significant reduction in the carbon emissions, the use of natural fibre composites reduces the weight of the vehicle to a larger extent and minimises the problems associated with the disposal of the vehicle after its service life. The main objective of the work is to develop a light weight, comparatively eco-friendly natural fibre hybrid composite reinforced with intraply carbon +E-glass plies and unidirectional sunn hemp mat interplies and nano silica particles and to evaluate its mechanical and thermal properties for possible application in automobiles. The addition of nano silica was varied between 1wt % to 4 wt %. Mechanical properties investigation through (tensile and impact tests) and thermo mechanical investigation through dynamic mechanical analysis (DMA) and heat deflection temperature (HDT) were carried out. Activation energy of the nano composites was determined using Arrhenius model. Failure analysis of the composites was carried out with field emission scanning electron microscopy (FESEM). Mechanical and thermal properties was found to be higher for the intra-interply polymer composite reinforced with carbon+E-glass fibres and unidirectional sunn hemp mats with 3 wt %. nano silica particles addition. The results obtained in this work will be useful in designing comparatively environmentally friendlier composite structures