scholarly journals Vibration Characteristics of Composite Beam Having Flax, Aloevera and Sisal Fibers as Reinforcements

Composites are highly significant due to their various advantages and natural fibre reinforced composites can be vastly used in automobile and aircraft interior applications. This paper principally deals with natural fibre reinforced composite (NFC) in which flax, aloevera, sisal fibres are selected to be reinforced in epoxy matrix (as inner laminate layers) and is used in combination with glass-epoxy (as outer laminate layers). Such composite beam structures are analysed in Ansys software employing FEM. The comparison for various NFCs is presented by evaluating effect on natural frequency due to various parametric variations like laminate stacking sequence, material hybridization, and presence of cut out.

2021 ◽  
Author(s):  
◽  
Matthew Thomson

<p>This thesis focuses on the application of high frequency ultrasound as a tool for performing non-destructive testing for pultruded fibre reinforced composite (FRC) rods. These composite rods are popular in the manufacturing, construction and electrical industries due to their chemical, electrical and strength properties. Such FRCs are manufactured on automated production lines that operate day and night. Non-destructive testing techniques are desired to quickly and accurately detectmanufacturing flaws such as coating thickness irregularities and surface cracks. Layers and cracks can present as large changes in acoustic impedance and will strongly reflect ultrasonic waves. Combined with their low cost, east of use and absense of potentially harmful radiation, ultrasound has proven popular worldwide for Non-Destructive Testing. Finite Element Analysis (FEA) was employed to investigate the propagation of ultrasonic waves through layers of material to simulate a thickness measurement and the ability of ultrasound to measure thicknesses was proven. Experimental work was conducted on two fibre reinforced composite samples with varying thickness coatings of plastic and paint. The thickness was measured accurately using immersion transducers at 50MHz and a resolution of 20μm was attained through the use of matched filtering techniques. Surface acoustic waves, particularly Rayleigh waves were investigated using FEA techniques so that the generation, scattering and detection of such waves was understood. This lead to the development of methods for detecting surface cracks in glass using Rayleigh waves and these methods were successfully used in experimental work. Wave propagation in fibre reinforced composites was modelled and experimentally investigated with the results confirming theoretical expectations. Finally a Rayleigh wave was launched onto a fibre reinforced composite sample however the amount of energy leakage into the water was so great, due to the acoustic impedance of water, the detection of the wave was prevented. The conclusion reached was that an immersion setup was not appropriate for launching a travelling Rayleigh wave.</p>


2005 ◽  
Vol 13 (6) ◽  
pp. 637-644
Author(s):  
Young Jun Cho ◽  
Jae Ryoun Youn ◽  
Tae Jin Kang ◽  
Sung Min Kim

An approach for predicting the effective thermal conductivities of fibre reinforced composites has been developed, based on a thermal-electrical analogy. In the voxelization method, the unit cell of the laminate composites is divided into a number of volume elements, and the material properties considering the local variations of fibre orientation have been given to each element. By constructing a series-parallel thermal resistance network, the thermal conductivities of a fibre reinforced composite in both in-plane and out-of-plane directions have been predicted. The reported thermal conductivities of a graphite/epoxy composite of a balanced plain weave laminate were used for the comparison with the predicted values of the model, and good agreement was found.


2019 ◽  
Vol 37 (3) ◽  
pp. 257-272 ◽  
Author(s):  
Chenkai Zhu ◽  
Jingjing Li ◽  
Mandy Clement ◽  
Xiaosu Yi ◽  
Chris Rudd ◽  
...  

This study investigated the effect of intumescent mats (M1 and M2) with different compositions on the post-fire performance of carbon fibre reinforced composites. The sandwich structure was designed for composites where M1 (carbon fibre reinforced composite-M1) or M2 (carbon fibre reinforced composite-M2) mats were covered on the composite surface. A significant reduction in the peak heat release rate and total heat release was observed from the cone calorimetric data, and carbon fibre reinforced composite-M1 showed the lowest value of 148 kW/m2 and 29 MJ/m2 for peak heat release rate and total heat release, respectively. In addition, a minor influence on mechanical properties was observed due to the variation of composite thickness and resin volume in the composite. The post-fire properties of composite were characterised, and the M1 mat presented better retention of flexural strength and modulus. The feasibility of two-layer model was confirmed to predict the post-fire performance of composites and reduce the reliance on the large amounts of empirical data.


2018 ◽  
Vol 32 (9) ◽  
pp. 1282-1302 ◽  
Author(s):  
T Rajmohan ◽  
R Vinayagamoorthy ◽  
K Mohan

In the modern years, natural fibre composites have been converted into significant materials in many industries such as automotive, aerospace and and so on. Several types of natural fibre composites, particularly plant-based fibre composites, have been developed and tested. However, their mixed nature, engineer’s requirement of experience, an understanding of machinability databases, limit setting and trouble in manufacturing are barriers to extensive use of composites. The final shape of the natural fibre–reinforced composites (NFRCs) are obtained by conventional and unconventional machining. Machining of these composites generates confront due to the heterogeneous and anisotropic nature. Different methodologies and tools are intended to overcome the machining defects. In this article, a wide range of literature review on machining of NFRCs is examined with focus on conventional and unconventional machining operation. This article also discusses the influences of machining parameters and optimum conditions for machining of NFRCs.


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