Non-Destructive Acoustic Test (NDAT) to Determine Elastic Modulus of Polymeric Composites (original) (raw)
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Non-destructive estimation of modulus of elasticity of wood polymer composite
Journal of the Indian Academy of Wood Science, 2017
Dynamic modulus of elasticity (DMoE) of wood polymer composites, prepared with varying proportion of wood content, was determined using flexural vibration and ultrasonic pulse transit time methods. The DMoE was compared with the flexural modulus as measured by standard three point bending test. The elastic modulus of the composite increased with the increasing fiber content. Both vibration methods exhibited a strong linear association with static modulus. DMoE by ultrasonic pulse method was higher compared to flexural vibration method at low wood content and the difference diminished at 50% wood in composites. Both the dynamic modulus were higher as compared to the static modulus at all fiber loadings, however the difference between dynamic and static modulus reduced non-linearly with increasing wood content.
2020
The study describes the mechanical characteristics of polymer matrix composite reinforced with vegetable jute fibers such as Young’s modulus variation according the orientation of the fiber. The jute manufacture fiber in warp and weft direction was associated by impregnation with a green liquid thermoplastic resin. Samples of stack laminated composite have been tested in static and dynamic analysis according the fiber orientations using acoustic emission monitoring. The obtained results for the dynamic tests have highlighted their approaches in relation to the static test. The acoustic emission data were processed using a global approach, in order to associate the acoustic signatures of the damage mechanisms during the test, and to understand their influence on the mechanical behavior of the material.
Polymer Bulletin, 2012
This work investigates the application of ultrasonic testing UT in evaluating natural fibre thermoplastic composites NFTC. The characterisation of sound propagation speed in the composite is intended to be a tool for evaluating the NFTC namely fibre content, fibre distribution and external factors' effects like relative humidity and stress. The quality of fibre distribution homogeneity can be assessed by mapping the returning signals of the emitted longitudinal ultrasonic wave. This study presents the measured sound speeds for a composite system of flax and polypropylene (PP). Flax fibre loadings rang from 0 to 60 wt%. Humidity factor is studied at 10, 50 and 95 % relative humidity RH levels. Different stress levels of 0, 10 and 20 MPa are applied on composite samples in an orthogonal direction to the longitudinal wave propagation direction. Using non-immersion: contact UT; an increasing linear trend of calculated longitudinal sound speed by 1 % is indicated per every 11 wt% increase of the applied flax fibres. This rate increased with more RH levels. More stress decreases the sound speed but in a trend parallel to the nonstressed samples. Finally, the distribution quality of the fibre is assessed using the ultrasonic technique. Results are compared with the reference corresponding PP-glass fibre composite. The high E-modulus and the density of glass fibres are opposite factors. Thus, the sound speeds for the both cases of 30 wt% flax and glass fibres are close and not more than 0.6 % different.
Identification of the elastic properties of composite materials
2013
The mechanical characterization of composite materials is a research axis of scientific and economic importance. In fact, it is essential to measure the elastic constants of a material with accuracy in order to realize structural analysis and to optimize the design. Among the developed methods, the static methods based on strain measurement present some disadvantages: destructive evaluation and difficulties of measuring the out-of-plane elastic modulus because of the thinness. These disadvantages could be avoided by the use of non-destructive dynamic methods such as modal analysis or ultrasonic waves evaluation. Among the non-destructive methods, ultrasounds are efficient. Besides, because of the accuracy of the results as well as the repeatability of the measures, scientists are generalizing this method. This paper presents a way to determine the mechanical properties of carbon fiber composite materials. This work underlines the results obtained of phase velocity at different incid...
Acoustical and Mechanical Characterization of Natural Fibre-Reinforced Composite : A Review
International Journal of Scientific Research in Science, Engineering and Technology, 2023
Noise pollution is increasing in this era as countries' development is faster. This noise pollution causes serious non-auditory effects on human health. As a result, it needs effective controls on noise pollution. Hence, use a natural fibre-reinforced composite for acoustical applications. Natural fibre-reinforced composites have various benefits, such as being eco-friendly, easy to manufacture, and effective in cost, and natural fibre improves the sound absorption, mechanical strength, and structural stability of the composite. The present review describes various techniques for measuring the acoustical and mechanical characteristics of natural fibre-reinforced composites. In addition to these acoustical (sound absorption coefficient, sound transmission losses, etc.) and mechanical (tensile, flexural, impact, etc.) characteristics are reviewed. Furthermore, this review paper studied an influencing parameter that affects the acoustical and mechanical characteristics of natural fibre-reinforced composites. these influencing parameters, such as fibre properties, density, porosity, sample thickness, binder amount, and filler material. In natural fibre-reinforced composites, increasing the percentage of the fibre density, binder amount, and filler material enhances sound absorption and mechanical strength, but these parameters have certain limitations, and crossing the limitation decreases the characteristics. reduce the porosity, decrease sound absorption, and increase sample thickness to increase acoustical characteristics. The conclusion states that the acoustical and mechanical characteristics of natural fibre-reinforced composites are enhanced when considering the performance-influencing parameters.
STUDY ON PROCESSING AND CHARACTERIZATION OF NONWOVEN COMPOSITES FOR ACOUSTIC APPLICATION
Over the last thirty years nonwoven composite materials, plastics and ceramics have been the dominant emerging materials. The volume and number of applications of composite materials have grown steadily, penetrating and conquering new markets relentlessly. Modern composite materials constitute a significant proportion of the engineered materials market ranging from everyday products to sophisticated niche applications. Nonwoven materials are increasingly used for many applications. Nonwoven fabrics are defined as web structures made by bonding or interlocking fibers or filaments by mechanical, thermal, chemical, or solvent means. Most research on nonwoven materials has focused on factors such as fiber size, air flow resistance, porosity, thickness, and density for the application of acoustic absorption and insulation due to its tremendous potential. The sound absorption and insulation performance of fibrous materials depends on its composition and structure. In general, the thicker the material and the higher the porosity in structure, the better the absorption. In general, textile materials are designed and integrated to increase the sound absorption coefficient. The porosity of materials increases the sound absorption coefficient as the sound wave contacts the fiber surface and dissipates energy. The acoustical insulation and absorption properties of nonwoven fabrics depend on the fiber geometry and fiber arrangement within the fabric structure. Another important parameter affecting acoustic performance is the bulk density of nonwoven fabrics that makes an influence on the volume of the fabric. The internal structures of other natural fibers such as cashmere, goose down, and kapok show an influence on acoustic performance. The acoustic absorption of the goose down and kapok are much greater than that of cashmere and acrylic fibers. For same type of fiber at certain sound frequencies, the sound absorption coefficient reduces along with the declining mass density. The efforts to produce economically attractive composite components have resulted in several innovative manufacturing techniques currently being used in the composites industry. Keywords: composite, Nonwoven, acoustic absorption, acoustical insulation,
2010
Several billion tons of fillers and reinforcements are used annually in the plastics industry, and there is a huge potential market for recyclable, energy efficient and more environmentally friendly composite materials. The use of medium strength and low strength fiber available in nature are having enough potential for other application where high strength are not critical but it can provide a feasible range of alternative materials to suitable conventional material. The systematic experimental study using developed mould-punch set up and testing aids was carried out for the effect of volume fraction of reinforcement on longitudinal elastic modulus of unidirectional cotton fiber reinforced polyester composites. The testing was carried out as per ASTM D3039/D3039M-08. The micro mechanics assessment of obtained experimental results with models available in literature for longitudinal elastic modulus forms an equally important constituent of present work.
Ultrasonic Testing of Fiber Reinforced Polymer Composites- An Overview
2014
Fiber reinforced composites are susceptible to fabrication defects, impact damage, moisture absorption, variability in material properties. It is often required to produce evidence through NDT methods to establish integrity of structures, repeatability of manufacturing process to ensure design stipulated strength, stiffness, thickness variation and material homogeneity. Usually a combination of complementary NDT is used for this. Conventional method of NDT, namely-Ultrasonic has been successfully applied to test, evaluate and certify composites.
Applied Composite Materials, 2019
This paper presents an effective and reliable non-destructive method to measure the Young Modulus of porous and out of plane Young Modulus of composite materials using sound waves. First, a Finite Element Model based on Representative Volume Element (RVE) is developed to demonstrate how the elastic properties of composite material can be estimated by acoustic measurements using an impedance tube test rig. Second, the results of the experimental measurement campaign was carried out to validate the proposed method. In particular, two soft elastic foams with different density, an epoxy-carbon fibre composite and vynilesterglass fibre composite were tested. In the proposed method, a two-microphone impedance tube setup was used where the measured acoustic pressures at two upstream locations allowed the estimation of the reflection coefficient and the acoustic impedance of the tested materials. Since the acoustic impedance can be expressed as a function of the longitudinal speed of sound (assuming a plane standing wave excitation), the elastic modulus can be estimated which is associated with the speed of sound. The elastic modulus measured using the proposed method were in good agreement with the values obtained by the standard methods such as tensile tests and ultrasound time of flight measurements. The proposed method would allow in an accurate and fast manner the non-destructive evaluation of Young Modulus of porous materials and for the first time the proposed approach is applied successfully to the measurement of out of plane Young modulus of composite materials.