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Glass fibre reinforced epoxy laminates are improved to enhance their impact tolerance capabilities by modifying the epoxy resin with the addition of CTBN 1300X8 and triphenylphosphine under a controlled atmosphere of inert nitrogen gas. When impacted by a steel projectile, the damage area of a modified laminate is significantly smaller (35-55%) than that of an unmodified laminate for the same impact energy level. The interlaminar energy release rate in Mode I (G[sub Ic]) is increased by 41% as a result of the modification while the interlaminar energy release rate in Mode II (G[sub IIc]) is enhanced by 47%. No significant adverse effects were found on the modulus or ultimate tensile strength. The modification of epoxy causes precipitation and separation of discrete rubber particles during curing of the epoxy which also enhances the interlaminar toughness and impact tolerance. [ABSTRACT FROM AUTHOR]

Biodegradable composites based on poly(butylene succinate) (PBS) and unidirectional plain jute fabrics have been developed. These composites were fabricated by compression molding of sandwiching 4–7 jute fabric layers between five and eight layers of PBS sheets. Surface modification of the jute fabric by alkali and combined alkali-silane treatments was investigated. The effects of surface modification on the mechanical and thermal properties of jute fabric/PBS biodegradable composites were studied. The mechanical properties of surface-treated jute fabric/PBS biodegradable composites were significantly higher than those of untreated ones. Compared with the alkali treatment, the combined alkali-silane treatment showed higher mechanical properties of the jute fabric/PBS biodegradable composites. The alkali-silane-treated jute fabric/PBS biodegradable laminated composite with six reinforced fabric layers (47.5 wt.%) achieved the best mechanical properties in this study, which showed an increase in tensile strength by 16.4%, tensile modulus by 10.8%, flexural strength by 24.2%, and flexural modulus by 21.9% compared with those of untreated one. Fractured surface morphologies of tensile specimens exhibited an improvement of interfacial fiber-matrix adhesion in the PBS biodegradable composites reinforced with surface-treated jute fabric. Thermal stability of the jute fabric/PBS biodegradable composites was remarkably to be intermediate between the PBS resin and the jute fabric. Surface-treated jute fabric/PBS biodegradable composites having good interfacial fiber-matrix adhesion resulted in stable composites with better thermal stability than that of untreated ones. [ABSTRACT FROM PUBLISHER]

Multi-layer spray deposited Al-8.5Fe-1.3V-1.7Si alloy was co-deposited with 15 vol% SiC particulate (SiCP). The microstructure of the composite as-rolled has been determined using transmission electron microscopy (TEM). Elevated temperature properties of the composite have been investigated by comparing the tensile mechanical properties at 20°C, 315°C and 400°C for the composite. The significance of these results for microstructure at elevated temperature, operating strengthening mechanisms and the effects of SiCP reinforcement in such an alloy system, is discussed. [ABSTRACT FROM AUTHOR]

The strengthening behavior of particle reinforced metal–matrix composites is primarily attributed to the dislocation strengthening effect and the load transfer effect. To account for these two effects in a unified way, a new multi-scale approach is developed in this paper incorporating the aspect ratio effect into the geometrically necessary dislocation strengthening relationships. By making use of this multi-scale approach, the deformation behavior of metal–matrix composites (MMCs) and metal–matrix nanocomposites (MMNCs) as a function of size, volume fraction, aspect ratio, etc. of the particles has been investigated. Comparison with the previously proposed models and the available experimental results reported in the literature for both MMCs and MMNCs systems demonstrates the superiority of the proposed model. [ABSTRACT FROM AUTHOR]

Epoxy/S2-glass reinforced composites (SGRPs) infused with Cloisite 30B nanoclays were manufactured using the vacuum assisted resin infusion molding (VARIM) process. Prior to infusion, the matrix and clays were thoroughly mixed using a direct mixing technique (DMT) and a high shear mixing technique (HSMT) to ensure uniform dispersion of the nanoclays. Structures with varying clay contents (1–3 wt%) were manufactured. Both pristine and SGRP nanocomposites were then subjected to mechanical testing. For the specimens manufactured by DMT, the tensile, flexural, and compressive modulus increased with increasing the clay content. Similarly, the tensile, flexural, compressive, interlaminate shear and impact strength increased with the addition of 1 wt% clay; however the trend reversed with further increase in the clay content. Specimens manufactured by HSMT showed superior properties compared to those of nanocomposites containing 1 wt% clay produced by DMT. In order to understand these phenomena a morphological study was conducted. Transmission electron microscopy (TEM) micrographs revealed that HSMT led to better dispersion and changed the nanoclay structure from orderly intercalation to disorderly intercalation giving multi-directional strength. [ABSTRACT FROM AUTHOR]

In this research, shape memory alloy (SMA) foils were embedded into carbon fiber reinforced plastic (CFRP) cross-ply laminates. When the tensile pre-strained SMA foil is heated, the SMA produces appropriate compressive stress (recovery stress) to suppress the transverse cracks in the laminates. In order to investigate the damage suppression effect, tensile loading–unloading tests were conducted for the CFRP cross-ply laminates. The test results implied that the recovery stress of embedded SMA foil suppressed the occurrence and the progress of the transverse crack. Then, to confirm that the damage suppression effect was caused by the embedded SMA foil, the one-dimensional (1D) shear-lag model considering the behavior of SMA was newly derived. Using this model, the progress of transverse crack density was predicted probabilistically. The simulation results showed the same tendency as the experimental results. As a result, it was proved that the embedment of SMA foils into CFRP laminates is effective to suppress the occurrence and growth of the transverse cracks. [ABSTRACT FROM AUTHOR]

Vapor grown carbon nanofibers (VGCF) were dispersed throughout phenylethynyl terminated polyimide 'Triple A PI (TriA-PI)'. TriA-PI is a newly developed thermosetting polyimide, and the cured polymer exhibits excellent mechanical properties and high glass transition temperature (Tg > 300°C). The resulting composites containing 0, 3.2, 7.7, and 14.3 wt% of VGCFs exhibited relatively good dispersion in macroscopic observations. Dynamic mechanical analysis (DMA) showed an increase in Tg with incorporation of VGCFs; however, increase in Tg was not pronounced compared to multi-walled carbon nanotube (MWNT) dispersion. The experimental result suggested that the VGCFs and MWNT are immobilizing the polyimide chains at elevated temperature, and the chemical and physical interactions between nanofibers and the polyimide are governed by the surface area of the nanofibers per unit volume in composites. [ABSTRACT FROM AUTHOR]

Accelerated weathering studies of untreated and treated oil palm fiber reinforced phenol formaldehyde composites and oil palm/glass hybrid fiber reinforced phenol formaldehyde composites were conducted. Thermal, water, biological and γ radiation effects on the composite properties were analysed. Mechanical properties such as tensile, flexural and impact properties of thermal and water aged samples were investigated. The extent of biodegradation and γ irradiation effects was estimated from variations in tensile and impact properties. The tensile and impact fracture mechanism and changes in fiber-matrix adhesion were studied using scanning electron microscopic analysis. The changes in the tensile and flexural stress-strain characteristics as well as deformation behaviour of aged composites are well explained by respective stress-strain curves. Mechanical performance of the composites decreased upon thermal ageing. Marked decrease in these properties of the composites is observed upon radiation ageing. However water immersion leads to an increase in strength properties in some treated composites such as on acetylation, silane, acrylonitrile grafting, isocyanate, permanganate treatment, alkali treatment etc. It is found that oil palm fiber increases the biodegradability of the composites. [ABSTRACT FROM AUTHOR]

In our previous experiments, the tensile net fracture stress of double-edge-notched carbon-carbon composite (C/C) specimens has been in some cases much higher than that of smooth specimens. To optimally utilize this phenomenon, the tensile fracture behaviour of multi-holed C/Cs with cross-ply lamination was examined. Multi-holed specimens with different numbers of holes and different distances between the holes were prepared and tensile fracture tests were conducted. FEM calculations were performed in order to study the stress distributions during the tensile tests. Higher tensile strength than that of smooth specimens was obtained in an optimal case on the basis of averaged net stress. The strength dependency on the specimen geometry could be explained mainly by the load sharing effect among the ligaments. [ABSTRACT FROM AUTHOR]