Effect of fibre orientations on the mechanical properties of kenaf–aramid hybrid composites for spall-liner application

This paper presents the effect of kenaf fibre orientation on the mechanical properties of kenaf–aramid hybrid composites for military vehicle's spall liner application. It was observed that the tensile strength of woven kenaf hybrid composite is almost 20.78% and 43.55% higher than that of UD and mat samples respectively. Charpy impact strength of woven kenaf composites is 19.78% and 52.07% higher than that of UD and mat kenaf hybrid composites respectively. Morphological examinations were carried out using scanning electron microscopy. The results of this study indicate that using kenaf in the form of woven structure could produce a hybrid composite material with high tensile strength and impact resistance properties.

Mechanical Properties of Bio-Based Epoxy Composites Reinforced with Hybrid-Interlayer Ramie and Recycled Carbon Fibres

The growing environmental concerns have led to attention on bio-based composite materials, such as the natural fibres, recycled carbon fibres and bio-based resins. Herein, the bio-based epoxy composites were reinforced with ramie fibre (RF) and recycled carbon fibre (rCF) via inter-layer hybridisation. The dynamic mechanical analysis, tensile, flexural and impact properties characterisation were conducted to analyse the mechanical behaviour of the specimens. Also, the morphology of fractured surface after mechanical tests was studied under a scanning electron microscope. When the volume ratio between RF and rCF was varied from 100/0 to 0/100, the flexural and tensile strength of composites was significantly increased, while the impact strength was reduced. Thus the maximum values of flexural strength (182 MPa) and tensile strength (165 MPa) were observed for rCF reinforced composite, whilst impact strength of 24 kJ/m2 was found for RF reinforced composite. Furthermore, the values of storage and loss modulus were increased with the rCF incorporation due to a greater degree of restriction with the addition of rCF into the matrix. The hybridisation was able to combine the specific properties of RF and rCF and optimise the mechanical performance of composites. Therefore, the alternative low-cost green composites are prepared which can replace synthetic materials for semi-structural applications.

Characterization of mean stem density,fibre length and lignin from two Acacia species and their hybrid

The objective of this study was to compare the wood properties related to wood pulp quality of two widely planted Acacia species viz.Acacia mangium Willd.and Acacia auriculiformis A.Cunn.Ex Benth.and their hybrid.Acid insoluble lignin content(Klason),mean stem density and fibre length differed considerably among the species and hybrids.A.mangium possessed a high percent of lignin content compared to A.auriculiformis and the Acacia hybrid.However,mean stem density of A.auriculiformis was higher than A.mangium and the hybrid.Fibre length of heartwood tissues was generally shorter than that of sapwood tissues.The hybrid had longer fibres than the parent species.Lignin was negatively correlated with mean stem density.Generally,the wood properties of the hybrid were superior to its parent species.The significant intraspecific variation observed for wood properties of Acacia species could be used in breeding superior hybrids combining desirable traits of the two species.Considering thedifficulty involved in accurately measuring the lignin content compared to mean stem density,selection for plants with low lignin content can be achieved by indirect selection of high mean stem density.

Conceptual Design of Glass/Renewable Natural Fibre-Reinforced Polymer Hybrid Composite Motorcycle Side Cover

This paper presents the development process relating to the conceptual design of glass/renewable natural fibrereinforced polymer hybrid composite motorcycle side cover.Motorcycle side cover is a component frequently made from plastic or steel that functions on covering the motorcycle parts,components and systems such as frame,battery,electrical systems and mechanical systems.Function Analysis Systems Techniques(FAST)is used to identify the functions of motorcycle side cover.The right-side cover of motorcycle model SYM E-Bonus 110 has been physically studied to identify the competitive benchmarking criteria.The functions and competitive benchmarking criteria are then compiled and integrated with the environmental requirements to identify the Product Design Specifications(PDS).The coir fibre has been selected from six identified dominant renewable natural fibre used for automotive component through integration of Ranking Method and Quality Based Selection(QBS).Then the polypropylene matrix is selected after shortlisting the existing thermoplastic that is used with coir fibre and has high suitability for injection moulding manufacturing.The polypropylene matrix is then evaluated using Weighted Evaluation Matrix(WEM)by comparing to benchmark material which is Acrylonitrile Butadiene Styrene(ABS).After that,the conceptual design development of glass/renewable coir fibre-reinforced polypropylene motorcycle side cover is carried out using an integrated Theory of Inventive Problem Solving(TRIZ)and Morphological Chart,followed by final conceptual design selection using integration of Pugh Scoring Method and QBS.The conceptual design development intended on improving the biodegradability to reduce pollution to the environment.However,the usage of glass/coir fibre-reinforced polypropylene hybrid composite may increase the weight due to higher density.Four innovative design concepts have been developed and the selected final concept design has the most minimum number of ribs and minimum thickness with the same ratio of glass fibre and natural fibre composition.

Hybrid Composites of Phosphate Glass Fibre/Nano-Hydroxyapatite/Polylactide: Effects of Nano-Hydroxyapatite on Mechanical Properties and Degradation Behaviour

Hydroxyapatite/polylactide (HA/PLA) composites have been intensively investigated for their potential as biodegradable fixation devices to heal bone fractures. However, most of these composites failed to achieve a bone-mimicking level of mechanical properties, which is an essential demand of the targeted application. In this study, the nano-hydroxyapatite/polylactide composites were used as the matrix and continuous phosphate glass fibres (PGF) served as the major reinforcement to obtain the nano-HA/PGF/PLA hybrid composites. While the PGF volume fraction remained constant (25%), the nano-HA content (in weight) varied from 0% to 20%. As nano-HA loading increased, the flexural modulus of the composites increased from 8.70 ± 0.35 GPa to 14.97 ± 1.30 GPa, and the flexural strengths were enhanced from 236.31 ± 10.83 MPa to 310.55 ± 22.88 MPa. However, it is found that the degradation rates are higher with more nano-HA loaded. Enhanced water absorption ability, as well as increased voids in the composites is possible reasons for the accelerated degradation of composites with higher nano-HA loading. The hybrid composites possess mechanical properties that are superior to most of the HA/PLA composites in previous research while maintaining the biodegradability. With a proper loading of nano-HA in composites of 10 weight percent, the composites are also found with improved mechanical properties without catastrophic degradation. The composites developed in this study have great potential as biodegradable bone fixation device with enhanced load-bearing ability as confirmed and superior bioactivity as anticipated.

Study of Mechanical Properties of Raffia Palm Fibre/Groundnut Shell Reinforced Epoxy Hybrid Composites

The mechanical properties of raffia palm fibre and groundnut shell particulate/epoxy (RPF/GSP/E) hybrid composites have been studied. Raffia palm fibres were treated with 10% NaOH solution at room temperature, and groundnut shell particulate of different sizes;75 μ, 150 μ and 300 μ were also chemically treated with 10% NaOH solution at room temperature. The hybrid composite was produced by hand lay-up technique with (10%, 20%, 30%, 40%, and 50%) reinforcements of raffia palm fibre and ground nut shell particulate in the ratio of 1:1. The treated fibres were taken with required weight fractions laid into the mould of size 200 × 150 × 5 mm3. Groundnut shell particulates were also taken with the required weight fraction, mixed with epoxy resin and the mixture was stirred thoroughly before pouring into the mould. Care was taken to avoid formation of air bubbles during pouring and the produced composite was cured under a load of 25 kg for 24 hours before it was removed from the mould. Effects of loading on the tensile, flexural and impact properties of the composite were evaluated. The significant findings of the results were that: tensile strength varied from 1.88 MPa to 9.56 MPa;Modulus of rupture (MOR) varied from 1.92 MPa to 41.6 MPa. While the modulus of elasticity, (MOE) values were in the range of 131.1 MPa to 4720 MPa and impact strength varied from 0.3 kJ/m2 to 1.6 kJ/m2. From the results obtained, the optimum mechanical properties were obtained at 40% loading of RPF/300 μ GSP/E composite. Considering these results, the composite material can be considered as an alternative material for use in automotive interior panels such as boot liner, side and door panels, rear storage shelf and roof cover.

Novel hybrid FRP tubular columns for sustainable mining infrastructure:Recent research at University of Wollongong

This paper introduces, for applications in the mining industry, an innovative hybrid column form which consists of an inner steel tube, an outer fibre-reinforced polymer(FRP) tube and an annular concrete infill between them. The two tubes may be concentrically placed to produce a section form more suitable for columns, or eccentrically placed to produce a section form more suitable for beams. The FRP is combined with steel and concrete in these hybrid structural members in such a way that the advantages of FRP are appropriately exploited while its disadvantages are minimized. As a result, these hybrid members possess excellent corrosion resistance as well as excellent ductility and seismic resistance. This paper summarizes existing research on this new form of structural members, and discusses their potential applications in mining infrastructure before presenting a summary of the recent and current studies at University of Wollongong(UOW) on their structural behaviour and design.

Coherent beam combining of hybrid phase control in master oscillator-power amplifier configuration

A novel scalable architecture for coherent beam combining with hybrid phase control involving passive phasing and active phasing in master oscillator-power amplifier configuration is presented. Wide-linewidth mutually injected passive phasing fibre laser arrays serve as master oscillators for the power amplifiers, and the active phasing using stochastic parallel gradient descent algorithm is induced. Wide-linewidth seed laser can suppress the stimulated Brillouin scattering effectively and improve the output power of the fibre laser amplifier, while hybrid phase control provides a robust way for in-phase mode coherent beam combining simultaneously. Experiment is performed by active phasing fibre laser amplifiers with passive phasing fibre ring laser array seed lasers. Power encircled in the main-lobe increases1.57 times and long-exposure fringe contrast is obtained to be 78% when the system evolves from passive phasing to hybrid phasing.

Axial variations in anatomical properties and basic density of Eucalypt urograndis hybrid(Eucalyptus grandis × E. urophylla)clones

We studied two clones of Eucalypt urograndis hybrid （Eucalyptus grandis × E. urophylla）, GR283 and GR330, grown in Tumkur district of Kamataka （India）, and felled 5-6 years old three trees of each clone. We recorded axial variations in heartwood content, bark properties, wood density and anatomical characteristics of wood in- cluding fibre length, fibre diameter, fibre wall thickness, lumen diameter, vessel frequency, vessel diameter and vessel element length. Clone GR283 had about 10 % heartwood, significantly lower than for clone GR330 （37 %）. Basic wood density along the tree height varied significantly within and between the clones. We observed significant variations in fibre length, fibre diameter and wall thickness within and between the two clones. Vessel frequency and vessel element length did not vary but vessel diameter differed significantly between the clones. With a greater proportion of sapwood, clone GR283 can be uti- lized for paper and pulp applications. Clone GR330 had a higher proportion of heartwood and lower wood density and, hence, is more suitable for light-weight material applications.

Mechanical Properties of Hybrid Cementitous Composites

Pulverised stem fibres of the natural sponge plant, SP, (Acanthus montanus) and stranded coconut fibre, CF, (Cocos nucifera) from the coir tree were used as reinforcements for thin cement sheets in this research work. The mixture of cement and pulverised waste paper, which formed the matrix, was maintained constant while the fibre mass concentration of both fibres were varied. The slurry formed by adding water to the mixture of the matrix materials and the reinforcement fibres, was poured into rectangular mould and consequently pressed to eject excess water. De-moulded samples were allowed to cure in the laboratory for twenty-eight days before flexural and compressive tests were carried out. The analysis of the experimental results established that sample coded as S4, with 30% CF and 70% SP, showed the most promising result. This implied that particulate reinforcement in cement matrix composite contributed to higher and improved flexural load bearing capacity and ductility when utilised in a higher proportion than long fibres.

MECHANICAL PROPERTIES OF HYBRID GLASS/SUGAR PALM FIBRE REINFORCED UNSATURATED POLYESTER COMPOSITES

A research has been carried out to investigate the mechanical properties of composites made by hybridizing sugar palm fibre （Arenga pinnata） with glass fibre into an unsaturated polyester matrix. Hybrid composites of glass/sugar palm fibre were fabricated in different weight ratios of strand mat glass fibres ： sugar palm fibres 4：0, 4：1, 4：2, 4：3, 4：4, and 0：4. The hybrid effects of glass and sugar palm fibre on tensile, flexural and impact properties of the composites were evaluated according to ASTM D5083, ASTM D790 and ASTM D256 respectively. Results have been established that properties of hybrid glass/sugar palm composites such as tensile strength, tensile modulus, elongation at break, toughness, flexural strength, flexural modulus and impact strength are a function of fibre content. The failure mechanism and the adhesion between fibres/matrix were studied by observing the scanning electron micrographs of impact fracture samples. In general, the incorporation of both fibres into unsaturated polyester matrix shows a regular trend of increase in the mechanical properties.

纤维金属混杂层板抗侵彻性能的仿真分析

【目的】根据舰船轻量化的设计要求,纤维增强复合材料存在着抗冲击性能差等问题,需对其抗冲击性能进行研究。【方法】建立有限元模型,对一种适于海洋环境的玄武岩/钢混杂层板的抗侵彻性能进行研究,并验证其有效性。再对各工况下混杂层板的弹道性能和失效行为进行对比分析。【结果】多数情况下3/2铺层靶板的防护性能最好,复杂的铺层结构能够优化混杂层板的失效形式,使背板附近的铺层更倾向于呈现拉伸断裂的破坏形式。【结论】该破坏形式有利于纤维增强复合材料发挥其性能优势,提升防护效果。

考虑节点负载的光纤通道多路数据混合传输方法

由于数据传输节点能量有限,易受到节点负载不均衡影响,无法选择有效的传输通道,因此节点存活率较低、时延较高。为此,提出了考虑节点负载的光纤通道多路数据混合传输方法。采用关键能量平均值计算方法,计算所有路由路径关键能量值,根据光纤通道整体能耗选择传输路径。通过可变边界的时间轴多路复用帧结构,建立初始传送路径,采用能量平衡法为多路径分配传输工作量,估算各路径所承载的数据传输量。充分考虑节点负载,计算从源节点到目标节点的路由能量消耗,避免了节点过量负载。采用时分复用与波分复用混合方式,实现光纤通道多路数据混合传输。实验结果表明,该方法最高时延达到0.5 s,节点存活率为0.96,能够有效实现光纤通道多路数据高质量混合传输。

纤维自密实高性能混凝土工作度的试验研究

工作度、强度、韧性及耐久性是自密实高性能混凝土(SCHPC)的主要性能指标,而工作度是保证混凝土具有高性能的重要前提。本文参照目前国际上的最新发展趋势,使用流变仪(rheometer)、流动槽(flow channel)、坍落流动板(slump flow panel)、J型环(J-Ring)和L槽(L-Box)等方法研究纤维自密实高性能混凝土(FR-SCHPC)的工作度。通过大量试验分析了不同掺量的钢纤维、PP纤维及组合纤维对新拌混凝土流动性、抗离析性、流经钢筋的间隙通过性能以及自流平能力的影响;为在实际工程中应用FRSCHPC提供了依据。

开发高性能复合材料中使用的新型纤维材料

复合材料的性能在很大程度上取决于增强体——纤维的性能、含量及使用状态。主要介绍了几种在开发研制高性能复合材料中使用的新型纤维材料,以及它们的性能、应用与开发动向。

陶瓷-尼龙纤维水泥基复合材料力学性能研究

研究了单一陶瓷纤维、单一尼龙纤维及陶瓷尼龙混杂纤维水泥基复合材料的力学性能．结果表明：单一陶瓷纤维在３％体积掺量时，２８ｄ抗压强度可提高４４％左右，抗折强度可提高７％～８％，抗冲强度可提高约１６％；０．０５％体积掺量的尼龙纤维使砂浆干缩开裂减小３０％～４０％；０．５％～２％体积掺量的尼龙纤维使砂浆抗冲强度提高到２～３倍．陶纤和尼纤体积掺量分别为２％～３％和０．２５％～１％的混杂纤维水泥基复合材料在拌和物流动性可取的情况下抗压、抗折、抗冲综合性能较好．

10个杨树杂种组合木材密度与纤维遗传变异研究

对保定5年生杨树无性系测定林和7年生育种资源保存林10个杂交无性系木材密度,纤维长、宽度分析结果表明:①不同杂种组合、个体间的木材密度、纤维长度均有很大变异。木材密度与速生特性之间呈微弱的负相关;纤维长度与生长性状相关不显著。②木材密度和纤维长度可以独立选择,从而选出密度较高,纤维较长和速生优质的杨树杂交新个体。③幼龄与中、成龄的木材密度相关显著,从而说明了在杨树材性育种中早期选择的可行性。研究证明,对华北地区来说,69杨为母本,欧亚黑杨及其种内杂种为父本是选育速生优质杨树新品种的优良组合。

玻璃纤维与混杂纤维自密实混凝土的工作性和强度试验研究

本文对掺玻璃纤维和混杂纤维自密实混凝土的抗压强度及其新拌混合物的工作性进行了试验研究,以用不同类型纤维,相同类型不同掺量的纤维自密实混凝土试验数据为依据。比较分析了不同类型及不同掺量纤维对自密实混凝土工作性和强度的响。探讨了素混凝土及纤维增强自密实混凝土的破坏机理。

超高模量聚乙烯纤维-碳纤维混杂复合材料冲击性能的研究

本工作以平面Ｃｈａｒｐｙ冲击、缺口与非缺口Ｃｈａｒｐｙ冲击全面地研究了本实验所制备的超高模量聚乙烯（ＵＨＭＰＥ）纤维－碳纤维混杂增强环氧复合材料的冲击性能。同时根据试样在冲击过程中的载荷－时间曲线以及试样在冲击破坏后的形貌对该类混杂复合材料的冲击破坏过程与冲击破坏模式进行了分析。结果表明，将ＵＨＭＰＥ纤维与碳纤维相混杂，复合材料的冲击性能呈现出明显的正混杂效应。

不同品种杂交棉的光合特性及产量比较

在大田栽培条件下,研究了杂交棉豫杂35、中棉29、标杂A2、标杂A1、经杂2号的主茎叶的光合特性及其产量和纤维品质,结果表明:豫杂35由于其叶片功能期Pn较高,且衰老慢,其叶片的Pn、Fv/Fm和ФPSⅡ日变化幅度又较小,对强光利用能力强,全天光合速率较高,从而获得显著高的最高产量;中棉29、标杂A2、和经杂2号获得较标杂A1显著高的产量;标杂A1由于叶片早衰且叶片光合性能相对较差,而产量最低,纤维品质较差。