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Fibre-reinforced polymers (FRPs) are composite materials of plastics reinforced with fibres. Cars, sea, aeronautics, and foundation projects progressively utilize fibre-reinforced polymers. This study aims to study the effect of adding multiwalled nanotubes fillers into the hybridized jute-glass FRP composites and their relative properties. This study uses multiwalled nanotubes (MWCNTs), and particles-hybrid jute-glass composites containing jute fibre chopped layer mats, woven glass mats, epoxy resin, and multiwalled nanotubes fillers were created using the hand layup method. After adding multiwalled nanotubes fillers in various weight proportions, the mechanical behaviours of fibre-reinforced polymers were analysed. The mechanical behaviours of laminated composites were tested using the ASTM standard; the following properties are tensile, flexural, and impact strength. The multiwalled nanotubes with 6% wt. attained the maximum mechanical properties compared to the 2 and 4 wt. % of MWCNTs. The E-based specimen contributes the most to the different types of specimens, with a contribution of 24.21% for tensile, 25.03% for flexural, and 24.56% for impact. The microstructures of hybrid composites were studied using a scanning electron microscope. [ABSTRACT FROM AUTHOR]

Ceramic laminates were produced by thermal pressing of pure alumina (Al2O3) and TiO2‐MnO‐doped alumina (d‐Al2O3) tapes and subsequently sintered at temperatures ranging from 1100 to 1250°C. The diffusion of dopants through the interface was investigated by optical (OM), scanning electron (SEM) microscopy, nanoindentation, and energy‐dispersive X‐ray spectroscopy (EDS) together with scanning transmission electron microscopy. Temperature‐dependent dopant diffusion and porosity profiles were, respectively, observed investigating the microstructure. For d‐Al2O3, the average grain size, hardness, and Young's modulus were higher when compared to pure alumina, while the dopants diffusion zone presented intermediate values of these properties. The increase in sintering temperature resulted in higher values of hardness and Young's modulus in both layers. A further investigation showed a gradual decrease in grain size, hardness, and Young's modulus from the doped to the pure alumina layer, corresponding to a decreasing gradient in the dopants concentration in the Al2O3 layer with increasing distance from the interface. High concentrations of Mn and Ti were observed at triple points and grain boundaries, as well as within alumina grains. [ABSTRACT FROM AUTHOR]

Aim: Mouthguard thickness influences the preventive effects against dental and oral injury. The aim of this study was to examine the difference in pressure-formed mouthguard thickness according to the laminate procedure used.Materials and Methods: The materials used were mouthguard sheets of 2.0-mm and 3.0-mm ethylene vinyl acetate, and pressure formed using a pressure former. Two forming conditions for laminated mouthguards were examined: the condition 23P used the 2.0-mm sheet as the first layer and 3.0-mm sheet as the second layer. The condition 32P used the 3.0-mm sheet as the first layer and 2.0-mm sheet as the second layer. The first layer was trimmed to cover only the anterior region; then, the second layer was formed over the first layer. Mouthguard thickness was measured at the labial surface of the central incisor, buccal surface of the first molar, and occlusal surface of the first molar. Statistical analysis was performed by two-way analysis of variance and Bonferroni method to analyze the differences in thickness by measurement region of mouthguards and forming conditions.Results: Mouthguard thickness differed in different regions of the central incisors and the first molars (P < .01). The thickness at the labial surface of the central incisor became statistically significantly larger on the 32P condition than that on the 23P condition (P < .01). The thickness at the buccal surface and the occlusal surface of the first molar became statistically significantly larger on the 23P condition than that on the 32P condition (P < .01).Conclusions: The thicknesses of the labial surface of the central incisor became larger when the sheet thickness of the first layer was larger. [ABSTRACT FROM AUTHOR]

The effective method of transformed differential quadrature (TDQ) is improved for the buckling design optimization of functionally graded (FG) carbon nanotube‐reinforced laminated composite quadrilateral (FG‐CNTRCQ) plates with arbitrary straight‐sided based on the first‐order shear deformation theory. The laminated plates with both uniformly and FG distributions of single‐walled carbon nanotubes varied along the thickness of layers are considered. The TDQ method is used to directly discretize the governing differential equations for an arbitrary straight‐sided physical domain without any need to transform the equations to the computational domain. In the presented genetic algorithm, the orientation of fibers is considered as the design parameter to obtain the optimum critical buckling loads in terms of different parameters including distributions of the fibers, number of layers, stacking sequence, CNTs volume fraction, geometrical parameters, and boundary conditions. The edges of the plates can take arbitrary end supports of simply and clamped boundary conditions. The formulation is developed based on the invariant terms to provide a systematic procedure with minimum computational cost. Some parametric studies are conducted to examine the effectiveness of the model for the design purpose of the FG‐CNTRCQ plates. POLYM. COMPOS., 39:E853–E868, 2018. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

ABSTRACT The aim of this study was to analyze how corona dosages above recommended levels affect film surface energy and hydrophobic recovery of such treated film surfaces as well as laminate bond strength of laminates made of these films. The adhesive for lamination was a polyurethane-adhesive with a dry film thickness of ∼5 µm. Polar and dispersive parts of the surface energy were measured frequently according to DIN 55660-2 (Owens-Wendt-Rabel-and-Kaelble method) for up to 140 days after corona treatment. The corona dosage had a value of up to 280 W min/m2. Laminate bond strength was measured according to DIN 55543-5. The effect of corona treatment was highest for low-density polyethylene (PE-LD) films, mean for biaxial-oriented polypropylene (PP-BO) films, and lowest for biaxial-oriented poly(ethylene terephthalate) (PET-BO) films. With increasing storage time, surface energy decreased, as expected. The higher the effect of corona treatment, the faster the polar part of surface energy decreased. At PE-LD, laminate bond strength increased with a higher corona dosage from 0.05 to 8.87 mN/15 mm, whereas at PET-BO and PP-BO laminate bond strength was so high that samples teared before delamination during bond strength testing. By our results is shown that corona dosages above recommended levels resulted in higher laminate bond strength. Only at PP-BO a reduction of laminate bond strength due to 'overtreatment' was be observed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45842. [ABSTRACT FROM AUTHOR]

A new research method based on vibration testing for the vibration fatigue of FRP was proposed in this paper. Through the testing on a closed-loop controlled vibration fatigue test system, the vibration fatigue phenomenon of typical carbon-fiber-reinforced plastic (CFRP) cantilevered laminate specimens was carefully studied. Moreover, a method based on the frequency response function was proposed to monitor the fatigue damage accumulation of specimens. On the basis of that, the influence factors that affect the vibration fatigue life of CFRP were experimentally studied. The influence of amplitude probability distribution of the vibration load spectrum on the fatigue life was deeply explored. Compared with Gaussian random vibration, the non-Gaussian random load has a significant impact on the vibration fatigue life of CFRP. The experimental results also showed that the magnitude of power spectral density (PSD) has a significant effect on the vibration fatigue life of specimens. For Gaussian vibration load, the frequency bandwidth almost has no effects on the vibration fatigue life of CFRP. However, for non-Gaussian vibration load, it has a great impact on the fatigue life. When PSD magnitude and frequency bandwidth are constant, the root mean square (RMS) is proportional to the vibration fatigue life of composites. [ABSTRACT FROM AUTHOR]

The experimental determination of capillary pressure drainage curves at the pore scale is of vital importance for the mapping of reservoir fluid distribution. To fully characterize capillary drainage in a complex pore space, we design a differential imaging-based porous plate (DIPP) method using X-ray microtomography. For an exemplar mm-scale laminated sandstone microcore with a porous plate, we quantify the displacement from resolvable macropores and subresolution micropores. Nitrogen (N2) was injected as the nonwetting phase at a constant pressure while the porous plate prevented its escape. The measured porosity and capillary pressure at the imaged saturations agree well with helium measurements and experiments on larger core samples, while providing a pore-scale explanation of the fluid distribution. We observed that the majority of the brine was displaced by N2 in macropores at low capillary pressures, followed by a further brine displacement in micropores when capillary pressure increases. Furthermore, we were able to discern that brine predominantly remained within the subresolution micropores, such as regions of fine lamination. The capillary pressure curve for pressures ranging from 0 to 1151 kPa is provided from the image analysis compares well with the conventional porous plate method for a cm-scale core but was conducted over a period of 10 days rather than up to few months with the conventional porous plate method. Overall, we demonstrate the capability of our method to provide quantitative information on two-phase saturation in heterogeneous core samples for a wide range of capillary pressures even at scales smaller than the micro-CT resolution. [ABSTRACT FROM AUTHOR]

The aim of this study is developing a new algorithm to design fiber angle and layer number of laminated composite plates. In this algorithm, fiber angles are determined using stress values and layer numbers are determined using maximum stress failure theory. Different design domains are used under different loading conditions and results are investigated to show the performance of the algorithm. Design time of composite materials is decreased and design performance is increased using this algorithm. More effective materials can be developed with respect to different loading conditions. POLYM. COMPOS., 38:268-276, 2017. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The fire structural response of sandwich composite laminates incorporating bio-derived constituents subjected to a turbulent flaming fire was investigated. Fire structural tests were conducted on thermal insulated sandwich composites incorporating a thin surface-bonded non-woven glass fibre tissue impregnated with char-forming fire retardant, ammonium polyphosphate. The sandwich composite laminates were loaded in compression at 10%, 15% or 20% of the ultimate compressive strength while simultaneously subjected to turbulent flames imposing an incident heat flux of 35 kW/m2. Generally, the failure time increased with the reduced applied compressive load. The thermal insulated sandwich composite laminates had considerably improved fire resistance in comparison to their unmodified counterparts. The unmodified composites failed 96 s earlier than the thermal insulated specimens when the compression load was 10% of the ultimate compressive strength. The presence of ammonium polyphosphate at the heat-exposed surface promoted the formation of a consolidated char layer, which slowed down heat conduction into composite laminate substrate. The fire reaction parameters measured via the cone calorimeter provided insights into the thermal response hence fire structural survivability of sandwich composite laminates. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Quasi-static indentation (QSI) and low-velocity impact tests have been conducted to laminated composite specimens made from different composite systems. C-scan and thermal deply techniques were used to observe the internal damage characteristics of the laminates. The test results show the effect of fibers and matrices on the permanent indentation and damage behaviors of composite laminates. Fiber breakage plays an important role in the formation of permanent indentation and the match between the fiber and matrix also has a significant influence on the permanent indentation and damage behaviors. A comparison shows the correlation between the peak load energy of the QSI tests and the knee point energy of the impact tests, based on which a condition for the prominent indentation formation was proposed for the impact tests. POLYM. COMPOS., 35:872-883, 2014. © 2013 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

ABSTRACT For large composite structures, such as wind turbine blades, thick laminates are required to withstand large in-service loads. During the manufacture of thick laminates, one of the challenges met is avoiding process-induced shape distortions and residual stresses. In this paper, embedded fibre Bragg grating sensors are used to monitor process-induced strains during vacuum infusion of a thick glass/epoxy laminate. The measured strains are compared with predictions from a cure hardening instantaneous linear elastic (CHILE) thermomechanical numerical model where different mechanical boundary conditions are employed. The accuracy of the CHILE model in predicting process-induced internal strains, in what is essentially a viscoelastic boundary value problem, is investigated. A parametric study is furthermore performed to reveal the effect of increasing the laminate thickness. The numerical model predicts the experimental transverse strains well when a tied boundary condition at the tool/part interface is used and the tool thermal expansion is taken into account. However, the CHILE approach is shown to overestimate residual strains after demoulding because of the shortcomings of the model in considering viscoelastic effects. The process-induced strain magnitude furthermore increases when the laminate thickness was increased, owing mainly to a decrease in through-thickness internal transverse stresses. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]