Theoretical Analysis on Deflection and Bearing Capacity of Prestressed Bamboo-Steel Composite Beams

A theoretical analysis of upward deflection and midspan deflection of prestressed bamboo-steel composite beams is presented in this study.The deflection analysis considers the influences of interface slippage and shear deformation.Furthermore,the calculation model for flexural capacity is proposed considering the two stages of loading.The theoretical results are verified with 8 specimens considering different prestressed load levels,load schemes,and prestress schemes.The results indicate that the proposed theoretical analysis provides a feasible prediction of the deflection and bearing capacity of bamboo-steel composite beams.For deflection analysis,the method considering the slippage and shear deformation provides better accuracy.The theoretical method for bearing capacity matches well with the test results,and the relative errors in the serviceability limit state and ultimate limit state are 4.95%and 5.85%,respectively,which meet the accuracy requirements of the engineered application.

Elevated Temperature Properties of Bamboo Shaving Reinforced Geopolymer Composites

Geopolymer is a new alternative cement binder to produce concrete.In the present study,a novel geopolymer composites containing bamboo shaving(0–2 wt.%)were fabricated and exposed to the temperatures of 200℃,400℃,600℃and 800℃.Physical properties,micro-structure,and mechanical strengths of the geopolymer composites were evaluated before and after heating in order to understand their thermal properties,which are essential for the use as building materials.As the temperature rises,the drying shrinkage and apparent porosity of the composites increase,while the compressive and bending strengths decrease.At the temperature range of 200℃–800℃,the residual compressive strength rates of the geopolymer composite containning 2 wt.%bamboo shaving were respective 73.8%,61.47%,56.16%,and 29.56%,meanwhile,the residual flexural strength rates were respective 46.69%,8.68%,2.52%,and 2.33%.Correspondingly,the residual compressive strength rates of pure geopolymer were respective 72.81%,61.99%,54.55%,and 14.64%;the residual flexural strength rates were 48.87%,5.69%,3.22%,and 2.47%,respectively.Scanning electron microscope(SEM),optical microscope,and X-ray diffractometry(XRD)were applied to find the microscopic changes.The strength loss in the geopolymer composites was mainly because of the thermal degradation of bamboo shaving and shrinkage of geopolymer matrix.Bamboo shaving has great potential as reinforcer in developing low-cost geopolymer composites and may be used for applications up to 400℃.

Effects of Hydrothermal Environment on the Deformation of the Thin Bamboo Bundle Veneer Laminated Composites

To overcome warping in thin bamboo bundle veneer laminated composites(TBLC),their hydrothermal deformation characteristics were systematically investigated in this study.It was found that TBLCs accelerated the release of internal stress in the thickness direction in a hydrothermal environment,which increased their warpage.TBLCs showed increased warpage in the width and diagonal directions upon increasing the temperature.The warpage of Type E increased by 155.88%and 66.67%in the width and diagonal directions,respectively,when the temperature increased from 25
C to 100
C.The symmetrical TBLC with cross-lay-up and odd layers displayed better hydrothermal stability.We revealed that the deformation of the TBLCs could be regulated under the synergistic effect of water and temperature.These results provide a scientific basis for improving the uniformity of bamboo bundle composite materials and for developing thin bamboo bundle fiber composite materials with designable structures and controllable performance.

Evaluation of statistical strength of bamboo fiber and mechanical properties of fiber reinforced green composites

Green composites made from bamboo fibers and biodegradable resins were fabricated with press molding.On the basis of the Weibull distribution and the weakest-link theory,the statistical strength and distribution of bamboo fiber were analyzed,and the tensile strength of green composites was also investigated.The result confirms that the tensile statistical strength of fiber fits well with two-parameter Weibull distribution.In addition,the tensile strength of bamboo fiber reinforced composites is about 330 MPa with the fiber volume fraction of 70%.This value is close to or higher than that of other natural fiber reinforced green composites.

Preliminary Study on Tensile and Impact Properties of Kenaf/Bamboo Fiber Reinforced Epoxy Composites

The application of natural fibers as reinforcement in composite material has increased due to environmental concerns,low cost,degradability and health concerns.The purpose of this study is to identify the best type of bamboo fibers to be used as reinforcement for kenaf(K)/bamboo hybrid composite.There were three types of bamboo fibers evaluated in this study which include bamboo mat(B),bamboo fabric(BF)and bamboo powder(BP).Chemical composition of B,BF,BP and K fibers were analyzed in this study.The effect of different types of bamboo fibers on tensile,impact,and morphological properties were investigated.The B/epoxy composites displayed the highest tensile strength(53.03 MPa)while K/epoxy composite had the highest tensile modulus(4.71 GPa).Scanning electron micrographs of B/epoxy composites displayed better fiber/matrix interfacial bonding in comparison to other studied composites.Results showed that impact strength of BF-based composite was highest(45.70 J/m).In conclusion,the tensile strength of B/epoxy composite is superior to the other bamboo reinforced composites and will be further evaluated in the next study.

Ballistic impact properties of woven bamboo-woven E-glass-unsaturated polyester hybrid composites

In this study, a laminated woven bamboo/woven E glass/unsaturated polyester composite is developed to combat a ballistic impact from bullet under shooting test. The aim of this study is to understand the fundamental effects of the woven bamboo arrangement towards increasing ballistic resistance properties. The work focusses on the ballistic limit test known as NIJ V50, which qualifies materials to be registered for use in combat armor panels. The results show that the composites withstood 482.5 m/s ± 5 limit of bullet velocity, satisfying the NIJ test at level II. The findings give a strong sound basis decision to engineers whether or not green composites are qualified to replace synthetic composites in certain engineering applications.

Flexural Properties of Long Bamboo Fiber/ PLA Composites

This paper describes the flexural properties of biodegradable composites made using natural fiber and biodegradable plastics. Biodegradable composites were fabricated from bamboo fiber bundles and PLA (polylactic acid) resin. In this research, effect of molding temperature and fiber content on flexural properties of bamboo fiber reinforced composites was investigated. The flexural strength of this composite increased with increasing fiber content up to 70%. The flexural strength of composites decreased at molding temperature of 180&degC. Biodegradable composites possessed extremely high flexural strength of 273 MPa, in the case of molding temperature of 160&degC and fiber content of 70%.

Strength, Fatigue Strength and Stiffness of High-Tech Bamboo/Epoxy Composites

A major problem in the strength data available for cellulose fibre-based materials is that the moisture content of the test specimens is rarely measured, and yet it is the dominant variable in the tests. Detailed strength and stiffness results are presented for Brazilian Dendrocalamus Giganteus bamboo at a wide range of moisture contents down to 2% and the fatigue curve is given for Chinese Moso bamboo at 4% moisture content. Techniques are described for handling the variability of these natural materials, both in design and in manufacturing quality control, for the mass production of large, high-tech composites wind turbine blades.

Numerical study of directional heat transfer in composite materials via controllable carbon fiber distribution

Carbon fiber reinforced polyamide 12(CF/PA12),a new material renowned for its excellent mechanical and thermal properties,has drawn significant industry attention.Using the steady-state research to heat transfer,a series of simulations to investigate the heat transfer properties of CF/PA12 were conducted in this study.Firstly,by building two-and three-dimensional models,the effects of the porosity,carbon fiber content,and arrangement on the heat transfer of CF/PA12 were examined.A validation of the simulation model was carried out and the findings were consistent with those of the experiment.Then,the simulation results using the above models showed that within the volume fraction from 0% to 28%,the thermal conductivity of CF/PA12 increased greatly from 0.0242 W/(m·K)to 10.8848 W/(m·K).The increasing porosity had little influence on heat transfer characteristic of CF/PA12.The direction of the carbon fiber arrangement affects the heat transfer impact,and optimal outcomes were achieved when the heat flow direction was parallel to the carbon fiber.This research contributes to improving the production methods and broadening the application scenarios of composite materials.

Control on Gradient Adhesive Loading of Porous Laminate:Effects on Multiple Performance of Composites with Bamboo Bundle and Sliver

Elementary units“bamboo bundle”and“bamboo sliver”were processed and cross-linked as“bamboo-bundle veneer(BBV)”and“bamboo-sliver veneer(BSV)”for preparation of laminated composites.The concept of“high-content-adhesive surface treatment”was raised to improve boards’performance,rather than increasing adhesive absorption of every layer’s porous unit.That is,some BBVs experienced an extra“dipping&drying”to absorb more resin(named“HBBV”).The effect of the amount of knitting threads was also discussed for influencing BBV’s quality.Results indicated that light transmittance of BBVs decreased as the amount of threads added from 3 to 8,while mechanical stiffness increased.Adding two skin layers of HBBVs symmetrically was helpful to enhance 24-hour underwater and 28-hour“boil-dry-boil”dimensional stability for boards with BSVs as core,while more than two pairs of HBBVs were needed to improve 28-hour“boil-dry-boil”dimensional stability of boards with BBVs as core.Two symmetrical surface layers of BBVs/HBBVs provided BSV-boards/BBV-boards with greater bending resistance,while such“surface treatment”would not raise shearing strength of BSV-boards upon 28-hour“boil-dry-boil”treatment.Besides,the data obtained from drop-hammer impact test indicated that more than two pair of surface BBVs or HBBVs were required for significant improvement in anti-impact property.

Effect of Filler Content and Alkalization on Mechanical and Erosion Wear Behavior of CBPD Filled Bamboo Fiber Composites

In this study the mechanical and erosion wear behavior of bamboo fiber reinforce epoxy composites filled with Cement By-Pass Dust (CBPD) were studied. The effect of CBPD content and alkalization on the various properties of these composites was also investigated. Taguchi’s orthogonal arrays are used for analysis of experiential results. It identifies significant control factors influencing the erosion wear and also outlines significant interaction effects. Analysis of variance (ANOVA) test has also been performed on the measured data to find the most significant factors affecting erosion rate. Finally, eroded surfaces of both untreated and alkali treated bamboo fiber reinforced composites were characterized using SEM.

The Role of Bamboo Nanoparticles in Kenaf Fiber Reinforced Unsaturated Polyester Composites

In this study,bamboo nanoparticles in concentration ranges from 0-5%were incorporated along with woven/nonwoven kenaf fiber mat into unsaturated polyester and the developed composites were further characterized.Bamboo chips were subjected to ball milling process for the synthesis of nanoparticles with a particle size of 52.92 nm.The effect that the incorporation of nanoparticles had on various properties of reinforced composites was further observed.Due to the high surface area of nanoparticles,incorporation of 3%of nanofillers contributed towards strong bonding and better wettability with matrix,thus resulting in excellent mechanical properties and thermal characteristics in reinforced unsaturated polyester composites.Furthermore,mechanical characteristics of reinforced composites were deteriorated by the addition of a higher percentage of nanoparticles(>3%)due to agglomeration,as confirmed by scanning electron microscopy.Moreover,ordered structural arrangement of woven kenaf textile fiber showed enhancement in interfacial adhesion and promoted superior mechanical strength in reinforced composites as compared with nonwoven composites.

Mechanical and Rheological Properties of Bamboo Pulp Fiber Reinforced High Density Polyethylene Composites:Influence of Nano CaCO_(3)Treatment and Manufacturing Process with Different Pressure Ratings

In order to investigate the effect of the relative motion of nano CaCO_(3)reinforced bamboo pulp fiber(BPF)/HDPE composite components on the mechanical performance,a comparative study was performed.BPF was treated by nano CaCO_(3)blending(BM)and impregnation modification(IM)technology.The composites were produced using hot press(HPMP),extrusion(EMP)and injection molding process(IMP).The physical morphology of BPF was similar at different manufacturing processes.Compared to the samples manufactured by HPMP,a decrease in the(specific)flexural strength of BPF/HDPE composites and an increase in those of composites treated by nano CaCO_(3)manufactured by EMP and IMP were observed.The injection molded composites exhibited the best values in the(specific)impact strength,(specific)tensile properties.IM had a greater effect on the rheological behavior of the composites than BM,and nano CaCO_(3)treatment most effectively affected the performance of the extrusion molded composites.

Engineered Wood/Bamboo Laminated Composites for Outdoor Hydrophilic Platforms:Structural Design and Performance

Landscape designers increasingly prefer to use wood/bamboo-based composites for outdoor hydrophilic platforms owing to their natural surface texture,high performance,and sustainability to facilitate extensive interaction between people and water and enable the full range of ecological functions of water resources.In this study,four laminated composite(LC)structures were designed and manufactured using fluffed bamboo and wood veneers.Their surface textures,profile densities,water resistances,and mechanical properties were then evaluated.The type of fluffed veneer of the surface layer determined the texture of the LC surface.The specific structures of fluffed bamboo and wood veneer laminations were found to affect the LC profile density variability,water resistance,and mechanical properties owing to the differences in the strength and interfacial properties of bamboo and wood fibers.Finally,the water resistance and mechanical properties of all four LCs were found to be much higher than the highest level specified in GB/T 20241-2006 for“laminated veneer lumber”and GB/T 30364-2013 for“bamboo scrimber flooring”,indicating that they are promising materials for structures and flooring,particularly for outdoor hydrophilic platforms.

Effects of characteristic inhomogeneity of bamboo culm nodes on mechanical properties of bamboo fiber reinforced composite

Dendrocalamus farinosus and Phyllostachys heterocycla bamboo logs were subjected to a novel treat- ment process for the preparation of bamboo fiber mats （BFMs）, and the obtained BFM were used to fabricate bamboo fiber reinforced composite （BFRC）. We studied the mechanical properties of the BFRCs manufactured from the mats with and without bamboo nodes. The pres- ence of nodes in BFM greatly reduced tensile strength, compressive strength, modulus of elasticity, and modulus of rupture of the BFRCs, while the BFRCs fabricated from BFMs with nodes possessed higher horizontal shear strength. Therefore, the nodes in bamboo culms were an important factor in the uniform distribution of mechanical properties, and BFMs should be homogeneously arranged to reduce the impact of nodes on the mechanical strengths of BFRCs.

Extraction,Optical Properties and Bio-Imaging of Fluorescent Composition From Moso Bamboo Shoots

A novel fluorescent composition was firstly isolated from natural winter fresh Moso bamboo shoots,and its optical properties were fully investigated by fluorescence spectroscopy.It could emit strong blue light both in solid and solution state,providing high fluorescence intensity in ethanol.The solution’s concentration and addition of water greatly affected the fluorescence intensity,high concentration and addition of much water could quench fluorescence.Apoptosis results showed that the fluorescent extract(0-25 mg/L)could not induce apoptosis of Hela cells.Confocal fluorescent microscopic imaging in human hepatocellular carcinoma cells(HepG2)was realized using the fluorescent extract,it could dye the whole cell well which was different from 4',6-diamidino-2-phenylindole(DAPI)only dying cell nucleus.The fluorescent extract may be candidate for future natural fluorescent bio-imaging agent.

基于NECP-Bamboo程序的商用压水堆乏燃料组件核素成分分析

乏燃料组件核素成分的精确计算是乏燃料临界安全分析等工作的输入条件,放射性源项计算是乏燃料组件核素成分分析的典型应用。国内现有程序由于存在数据库中核素种类不全、辐照过程无法完全模拟等弊端,限制了乏燃料后处理安全分析的可靠性和经济性。本文基于完全自主化的压水堆堆芯分析软件NECP-Bamboo,研发了商用压水堆乏燃料组件核素成分计算程序Bamboo-SFuel,利用辐照后实验(PIE)实测数据对核素成分进行了定量验证与分析,通过与Scale程序包计算结果进行对比验证了程序源项计算的精度,还探究了不同燃耗数据库对核素成分和源项计算结果的影响。数值结果表明,Bamboo-SFuel能精确分析不同辐照条件下商用压水堆乏燃料组件的核素成分和放射性源项,使用NECP-Bamboo程序中不同核素数目的燃耗数据库对重要核素成分计算结果影响不大,但对总的放射性源项计算结果影响较大;基于内置的包含1547种核素的燃耗数据库,该程序可同时给出可靠的乏燃料临界安全分析和辐射安全分析关注的重要核素成分。

Analysis and characterization of microstructures of a TiO_2/bamboo charcoal composite and modified poplar veneer

A type of TiO/bamboo charcoal composite made by a dip-dry method was loaded onto wood veneer with a vacuum- pressure method in order to prepare modified poplar veneer. The pore structure parameters and surface morphology of the TiO2/ bamboo charcoal composite were determined and analyzed by means of a porosimetry analyzer and SEM. The results show that the surface morphology of the composite does not change after being loaded with nano TiO2. However, its specific surface area （359.814 m^2·g^-1）, pore volume （0.317 cm^3.g^-1） and average pore diameter （3.526 nm） increased; particularly the cumulative volume of pores was increased by 65.83%. In addition, the distribution range of the pores was wider than that of the bamboo charcoal. Combining the SEM of unmodified and modified poplar veneer, the results of X-ray photoelectron spectroscopy revealed that actually some TiOz compounds, i.e., 4.08%, are imbedded in the modified poplar veneer.

Strength Performance and Microstructure Characteristic of Naturally-Bonded Fiberboard Composite from Malaysian Bamboo(Bambusa vulgaris)

This study investigated the mechanical properties and microstructural characteristics of fiberboard composite produced by naturally-bonded Malaysian bamboo fiber(Bambusa vulgaris).The components that obtained through soda pulping of bamboo culms such as fiber and black liquor,were used for the preparation of high-density fibreboard composite at two target densities of 850 and 950 kg/m^(3).The bamboo fiberboard composite(BFC)were then produced at 200°C and two pressing parameters of 125 and 175 s/mm.The mechanical properties,e.g.,flexural strength and internal bonding(IB)of BFC samples were evaluated according to BS EN 310:1993 and BS EN 319:1993,respectively.It was found that the mechanical performance of the composite with 850 kg/m^(3)density was significantly higher than 950 kg/m^(3)ones,especially for the samples with 125 s/mm pressing parameter.Microstructure characteristic of the BFC samples illustrated that the fiber linkages were cracked in the composites with higher density,e.g.,the composite with the density of 950 kg/m^(3)and also black liquor were slightly degraded at longer pressing time,which led to the reduction in mechanical properties,especially in IB strength.

Mechanical Properties of Uni-Directional Long Bamboo Fiber/Bamboo Powder Composite Materials

This paper describes the mechanical properties of the composite materials produced using long bamboo fiber and bamboo powder. Bamboo fiber and powder can be hot press-molded much like plastic materials, and the use of these materials in place of plastic products would reduce the environmental impact of extensive plastic use. In this study, the tensile and flexural properties of molded uni-directional long fiber reinforced composites made from bamboo fiber bundles and Bamboo powder were examined. The results showed that the tensile and flexural strength of bamboo fiber/powder composites were increased with increasing fiber content. On the other side, both strengths of composite were decreased with increasing molding temperature after 180℃. The highest tensile and flexural strengths of the bamboo fiber reinforced bamboo powder composites specimens which were tested were recorded at 169.9 MPa and 221.1 MPa, respectively.