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1.
In this paper, perforated composite panel was combined with porous and resonance structures to investigate the influence on acoustic absorption and resilient properties. The perforated composite panel was fabricated based on highdensity flexible-foam via perforating and reinforcing with laminated hybrid nonwoven fabric. Effect of aperture size (AS) (ranging from 3 mm to 6 mm), perforation ratio (PR) (5 %, 10 %, 15 % and 20 %) and perforation depth (PD) (25 %, 50 %, 75 % and 100 %) on the compressive hardness, rebound resilience and acoustic absorption properties was explored. Multiply hybrid nonwoven fabric which was fabricated with low-melting point polyester (LMPET), flame-retardant polyester (FRPET) and recycled Kevlar fibers was utilized to reinforce the flexible composites and improve the acoustic property. Nonwoven that was fabricated with entangled LMPET fibers had porous structures which could reinforce the flexible foam and enhance the acoustic absorption properties. The result revealed that the continuity and supporting of porous flexible foam had directly influence the compressive hardness. The maximum hardness of the flexible-foam based perforated composites reached 420 N. The rebound resilience result showed that the sample had high resilient structure and the resilience was up to 48 %. The perforated flexible composites plate (PFP) with 4 mm-AS performed the highest acoustic absorption coefficient at 0.9. The acoustic absorption coefficient was higher than 0.8 in the frequency range from 800 to 1600 Hz and 1600 to 2400 Hz when perforated composites had 4 mm-AS at 5 % and 10 % perforation ratio. With the increase in perforation ratio, absorption peak moved from 3200 Hz to 4000 Hz. Hybrid nonwoven laminated layer help to broaden the frequency range of acoustic absorption of perforated high-density flexible foam based composites panel. Acoustic absorption coefficient was higher than 0.4 when frequency ranging from 900 Hz to 4000 Hz.  相似文献   

2.
This study focused on the fabrication and acoustic property evaluation of sandwich cover-ply-reinforced highresilience thermal-bonding nonwoven hybrid composites. P-phenyleneterephthalamides and bicomponent high-resilience bonding polyester intra-ply hybrid nonwoven fabrics were compounded with glass plain fabric to produce the high strength sandwich structural cover ply by means of needle punching and thermal bonding to reinforce the whole composites and dissipate energy when being impacted. Then, the acoustic absorption properties of the homogenous intra-ply hybrid meshwork layer were investigated before and after being reinforced with the aforementioned cover ply. The influencing factors, including areal density, fiber blending ratio, needle punching depth, and air cavity thickness between back plate of the impedance tube and composites, were comparatively investigated. Results revealed that hybrid composites exhibited exceedingly high acoustic absorption properties. Acoustic absorption coefficients were promoted with increases in areal densities and fiber blending ratio of 3D crimped hollow polyester, particularly at low-mid frequency range. In addition, needle punching depths and back air cavity thicknesses considerably affected the average absorption coefficients. The meshwork center layer reinforced with sandwich structural cover-ply perform high resilience properties.  相似文献   

3.
This study proposes a combination for reciprocal reinforcement between warp knitting spacer fabrics and PU foams. PET/Kevlar nonwoven fabrics are made with an 80:20 ratio and an incorporation of various needle-punching speed of 100, 150, 200, 250, and 300 needles/min. Ascribing to having an optimal bursting strength, sound absorption coefficient, and limited oxygen index (LOI), the PET/Kevlar nonwoven fabric that is made by 200 needles/min are selected to be combined with a glass-fiber fabric by applying needle punch in order to form a surface layer. Next, warp knitting spacer fabrics and the nonwoven fabrics are laminated, followed by being combined with polyurethane (PU) foam that are featured with different densities of 200, 210, 220, 230, and 240 kg/m3 in order to form spacer fabric/PU foam composites with multiple functions. The composites are then tested with a drop-weight test, a compression test, a bursting strength test, a sound absorption test, and a horizontal burning test. The test results indicate that all spacer fabric/PU foam composites reach a horizontal burning level of HF1, and their sound absorption coefficients at 2500-4000 Hz also suggest a satisfactory sound absorption. In particular, the optimal residual stress and compressive strength are present when the composites contain 210 kg/m3 PU foam. Similarly, the optimal bursting strength of the composites occurs when they are composed of 230 kg/m3 PU foam. The spacer fabric/PU foam composites are proven to have high strengths, sound absorption, and fire retardant, and thus have promising potentials for use as construction materials and light weight composite planks.  相似文献   

4.
In this research, we fabricated a series of PVA membranes loaded with 0 wt.%, 1 wt.%, 3 wt.%, 5 wt.% ZrC and 0 wt.%, 1 wt.%, 3 wt.%, 5 wt.% TiO2 using a spiral vane electrospun machine respectively. There were 2 sizes of TiO2 nano particles: 10 nm and 200 nm. We tested sound absorption properties of needle-punched nonwovens as well as the composite of nano membranes and needle-punched nonwovens by an impedance tube at the frequency range from 500 Hz to 6500 Hz. Besides, we tested morphological characterization of nano membranes by scanning electron microscope (SEM) and crystalline properties by X-ray diffraction (XRD). We investigated the sound absorption properties of composites as well as the effect of ZrC, TiO2, nano particle sizes and cavity depth on sound absorption properties. Results showed that sound absorption properties of composites increased at the whole range of frequency compared to those of needle-punched nonwovens. When loaded with ZrC nano particles, sound absorption properties of composite shifted to a higher frequency region, and with increasing content of ZrC, sound absorption properties were better above 2500 Hz. However, when loaded with TiO2, sound absorption properties were better at lower frequency. With 3 wt.% TiO2, sound absorption coefficient reached the best at the frequency range from 500 Hz to 1500 Hz. Besides, 200 nm TiO2 was more conductive to the increase of sound absorption properties at lower frequency region compared to 10 nm TiO2. Sound absorption properties of composites with air back cavity shifted to a lower frequency region, too. SEM showed that there was nano particle aggregation when loaded TiO2 nano particles. XRD showed that ZrC nano particles loaded in PVA nano fiber retained their crystalline structure while TiO2 didn’t. It appeared from the results that nano particles had an effect on sound absorption materials, with different kinds and different sizes, sound absorption properties will improve in different ranges of frequency  相似文献   

5.
The aim of this study is to examine the efficacy of the coconut fiber on the sound absorption and thermal insulation performance towards the composite nonwoven fabrics. The 2D polyester fiber and 12D fire retardant three-dimensional hollow crimp polyester fiber are individually mixed with 4D low-melting point polyester fiber (4DLMf) to produce 2D polyester nonwoven fabric (2D-PETF) and 12D polyester nonwoven fabric (12D-PETF) respectively. Subsequently, the coconut fiber (CF) is then laminated with the 2D-PETF and 12D-PETF to fabricate two types of PET/CF composite boards through the multiple needle-punching techniques. Accordingly, the sound absorption, thermal insulation, Limiting Oxygen Index and relative mechanical properties of the PET/CF composite boards are evaluated properly. The experimental results reveal that both types of PET/CF composite boards possess excellent thermal insulation performance and fire resistance property. Also, for both types of PET/CF composite boards, the average sound absorption coefficient increases with the increased amount of CF.  相似文献   

6.
High-performance composites by super fiber are difficult to apply at industrial field due to the high cost. To overcome this problem, there is a need to widely spread the use of the excellent composites. The composites with superior mechanical performance were investigated by a suitable stacking combination under limited amounts of a raw material. Carbon/aramid hybrid composites were soundly manufactured using the VARTM process. The excellent combinations of both the tensile and bending properties were determined. The lamination position and the continuous cumulative count of reinforcements play an important role in the strength and stiffness.  相似文献   

7.
Kenaf/empty fruit bunch/polylactic acid (kenaf/EFB/PLA) hybrid biocomposites were prepared using hot press technique. The ratio of fiber to polylactic acid was set at 60:40 with 1:1 ratio between kenaf and empty fruit bunch fibers. Physical, mechanical and thermal properties of hybrid biocomposites were subsequently characterized using Fourier transform infrared spectroscopy, scanning electron microscope, X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, tensile and water absorption tests. Test results indicated that mechanically stronger fiber was able to support the weaker fiber. Hybrid fiber biocomposite had higher crystallinity as compared to single fiber biocomposite. Water absorption of hybrid composite was higher as compared to single fiber composite. Thermal result revealed that hybridization of fiber was not significantly influence the thermal properties of composites. However, the presence of two different fibers proposed good wettability properties, which could reduce the formation of voids at the fibers-polymer interface and produce composites with high stiffness and strength.  相似文献   

8.
Textile sound absorbents are getting more and more popular on the market as noise reduction is a major requirement for human comfort today. In this paper we focus on a new textile material for sound absorption, by investigating the acoustic characteristics of nanofibers. Through impedance tube method we measured the sound absorption coefficients of multiple layers of nanofiber webs and compared those with microfiber materials per fabric weight. We also examined the effect of layers of nanofiber webs on regularfiber knitted fabric on sound absorption. The test results showed that the sound absorption coefficients of nanofiber layers were superior that of microfiber fabrics in the frequency range 1000–4000 Hz. In this range, the sound absorption of nanofiber webs improved with numbers of layers. Also, adding nanofiber web plies to regularfiber fleece increased the sound absorption coefficient with 85 % at 4000 Hz. From our results we could observe differences in the sound absorption coefficients between two test methods, which are higher absorbance coefficients through the reverberation room method than impedance tube method.  相似文献   

9.
Effects of needle-punching and thermo-bonding on tensile property, air permeability, puncture resistances and EMI shielding effectiveness were discussed for carbon-reinforced composite and glass-reinforced composite. The result shows that, needle-punching significantly improves static and dynamic puncture resistances. As increase of needle-punched density, static and dynamic puncture resistances show firstly increasing and then decreasing trend. Thermo-bonding almost has no influence on static puncture resistance, but effectively decreases dynamic puncture resistance. Comparatively, carbon-reinforced composite shows higher static and dynamic puncture resistances than glass-reinforced composites when being needle-punched at 200 needles/cm2. Meanwhile, carbon-reinforced composite has superior EMI shielding effectiveness to 40–60 dB at frequency of above 1 GHz, reaching 99.99 % shielding efficacy.  相似文献   

10.
This work deals with the study of acoustic performance of struto nonwovens and their relation to fabric air permeability. In order to achieve the objective of the research, sound absorption coefficient of struto nonwovens was determined via impedance tube method, the average value of sound absorption coefficient (α?) was calculated. Air permeability of struto nonwovens was examined by using FX3300 Textech Air Permeability Tester. Results showed that struto nonwoven exhibited good absorption ability at frequency bands 3000-6400 Hz while it was ineffective for frequency lower than 3000 Hz. Struto nonwovens with high GSM and fabric thickness showed better acoustic performance and lower air permeability. It was observed that α? was inversely proportional to air permeability, with correlation coefficient 0.95. It was concluded that air permeability can be used as a criterion of sound absorption behavior of struto nonwovens. A lower air permeability suggests a better sound absorption performance for struto nonwoven fabrics.  相似文献   

11.
Present technological development and innovation needs a better class of material that meets all the practical applications along with its environmental friendly nature and economical value. Hybrid natural fiber composites, a sector of natural composites meets these requirements. This paper deals with fabrication, mechanical characterization of a hybrid (Jute+Flax+GFRP) composite and also the comparison of it with the (Jute+GFRP) based composite. These composites are fabricated using hand lay-up technique. The arrangement of hybrid composite is such that a layer of vertically laid flax fiber is flanked between layers of horizontally laid jute fiber. Epoxy resin alongside with HY951 hardener is used as the binding agent throughout the layer. Glass fiber laminates are used on both sides for improving the surface finish and surface hardness. The volumetric fraction is such that one third of total volume is occupied by Jute and Flax fibers. Test results shows that the hybrid natural composite has excellent properties under tensile, flexural loading. At last failure morphology analysis is done using Scanning Electron Microscope (SEM) and the internal structure of the broken specimen is discussed.  相似文献   

12.
In this work, hybrid composites were fabricated by hand layup method to hybridize treated Pineapple leaf fibre (PALF) and kenaf fibre (KF) in order to achieve superior mechanical properties on untreated hybrid composites. Silane treated PALF/KF phenolic hybrid composites were prepared on various fibre fraction to investigate mechanical properties and compared with untreated PALF/KF phenolic hybrid composites. The effects of silane treatment on hybrid composites were investigated by fourier transform infrared spectroscopy (FTIR) and found very effective peaks. Effects of treated hybrid composites were morphologically investigated by using scanning electron microscopy images and analysed the tensile results. Treated PALF/KF phenolic hybrid composites enhanced the flexural strength, modulus, impact strength and energy absorption while tensile strength and modulus decreased. The overall performances of 70 % PALF 30 % Kenaf hybrid composites were improved after silane treatment. Silane treatment of fibres improved the mechanical performance of hybrid composites and it can be utilized to produce components for building structure, materials and automobile applications.  相似文献   

13.
In this study, we report the fabrication and evaluation of a hybrid multi-scale basalt fiber/epoxy composite laminate reinforced with layers of electrospun carbon nanotube/polyurethane (CNT/PU) nanofibers. Electrospun polyurethane mats containing 1, 3 and 5 wt% carbon nanotubes (CNTs) were interleaved between layers of basalt fibers laminated with epoxy through vacuum-assisted resin transfer molding (VARTM) process. The strength and stiffness of composites for each configuration were tested by tensile and flexural tests, and SEM analysis was conducted to observe the morphology of the composites. The results showed increase in tensile strength (4–13 %) and tensile modulus (6–20 %), and also increase in flexural strength (6.5–17.3 %) and stiffness of the hybrid composites with the increase of CNT content in PU nanofibers. The use of surfactant to disperse CNTs in the electrospun PU reinforcement resulted to the highest increase in both tensile and flexural properties, which is attributed to the homogeneous dispersion of CNTs in the PU nanofibers and the high surface area of the nanofibers themselves. Here, the use of multi-scale reinforcement fillers with good and homogeneous dispersion for epoxy-based laminates showed increased mechanical performance of the hybrid composite laminates.  相似文献   

14.
This paper presents the three-point bending properties of 3D needle-punched composites with two fiber architectures at room and elevated temperatures. The influences of temperature and fiber architectures on the load/deflection curves, bending strength and bending stiffness are analyzed. Macro-Fracture morphology and SEM micrographs are examined to understand the damage and failure mechanism. The results show that the bending properties of plain structure needle-punched composites are superior to those with non-woven structure. Meanwhile, the bending properties of composites decrease significantly with the increase of testing temperature. Moreover, the damage and failure patterns of composites vary with fiber architecture and testing temperatures. For the plain structure, 90 ° and 0 ° fiber bundles can bear the load together. At room temperature, the composite shows brittle fracture feature and exhibits local damage with matrix cracking, breakage and tearing of the fibers. While at a higher temperature, the composite shows less fracture and becomes more softened and plastic. It damages with matrix cracking, falling off and plastic deformation, fiber layer/web delaminating, and interface debonding.  相似文献   

15.
Woven Kenaf/Kevlar Hybrid Yarn is the combination of natural and synthetic fibers in the form of thread or yarn. The yarn is weaved to form a fabric type of fiber reinforced material. Then, the fabric is fabricated with epoxy as the resin to form a hybrid composite. For composite fabrication, woven fabric Kenaf/Kevlar hybrid yarn composite was prepared with vacuum bagging hand lay-up method. Woven fabric Kenaf/Kevlar hybrid yarn composite was fabricated with total fiber content of 40 % and 60 % of Epoxy as the matrix. The fiber ratios of Kenaf/Kevlar hybrid yarn were varied in weight fraction of 30/70, 50/50 and 70/30 respectively. The composites of woven fabric Kenaf/Epoxy and woven fabric Kevlar/Epoxy were also fabricated for comparison. The mechanical properties of five (5) samples composites were tested accordingly. Result has shown that of value of strength and modulus woven fabric Kenaf/Kevlar Hybrid Yarn composite was increased when the Kevlar fiber content increased. Therefore, among the hybrid composite samples result showed the woven fabric Kenaf/Kevlar Hybrid Yarn composites with the composition of 30/70 ratio has exhibited the highest energy absorption with 148.8 J which 28 % lower than Kevlar 100 % sample. The finding indicated there is a potential combination of natural fiber with synthetic fiber that can be fabricated as the composite material for the application of high performance product.  相似文献   

16.
In this paper, the bending properties of woven carbon/glass and carbon/aramid fabric-reinforced polymer laminates is studied using a combination of experimental analysis and fracture observation. Six types of each hybrid composite were manufactured by lamination of the carbon/aramid fabric and carbon/glass fabric using VARTM. Bending behaviors were fundamentally evaluated for the six types of monolithic composites laminated by the same fabric. The objective was to achieve a good bending strength by effective combination of composite structures using limited amounts of a raw material. It was shown that the bending property was different, depending on the type of fiber, lamination structure, and the number of layers.  相似文献   

17.
The dielectric spectrums of the cellulose acetate fiber/air (C/A) samples and the cellulose acetate fiber/air/oil (C/A/O) samples were measured with a broad band dielectric spectrum measurement system at frequencies with a logarithmic distribution from 0.1 Hz to 20 MHz. The experimental results showed that for the C/A samples, the relative permittivity varied weakly with frequency for the C/A samples, especially in the high frequency band. Hence, the mass of the cellulose acetate fibers was estimated by the dielectric spectrums of the C/A samples at a high frequency. For the C/A/O samples, the relative permittivity increased rapidly while the frequency decreased in the low frequency band, but it had little interaction with the frequency at the high frequency band. Therefore, the oil mass was estimated by dielectric spectrums of the C/A and C/A/O samples using the low frequency band. The oil content of cellulose acetate fibers was then calculated along with the estimated oil mass and cellulose acetate fibers mass.  相似文献   

18.
In the first stage, polyethylene terephthalate (PET) fibers and Kevlar fibers are combined at a blending ratio of 80/ 20 wt% in order to form PET/Kevlar nonwoven fabrics. Two pieces of PET/Kevlar nonwoven fabrics that enclose a carbonfiber (CF) interlayer are then needle punched in order to form PET/Kevlar/CF (PKC) composites. In the second stage, the sandwiches compose PKC composites as the top and the bottom layers, as well as an interlayer that is composed of a spacer fabric and polyurethane (PU) foam. PU foams have different densities of 200, 210, 220, 230, and 240 kg/m3. These resulting nonwoven fabric/spacer fabric/PU foam sandwiches are then tested using a drop-weight impact test, a compression test, a bursting strength test, a sound absorption test, and a horizontal burning test. The test results indicate that the optimal properties of sandwiches occur with their corresponding PU foam density as follows: an optimal residual stress (240 kg/m3), an optimal compressive strength (240 kg/m3), and an optimal bursting strength (220 kg/m3). In addition, the sandwiches reach the HF1 level according to the horizontal burning test results. They also have an average electromagnetic interference shielding effectiveness of -48 dB, as well as a sound absorption coefficient of 0.5 in a frequency between 1500-2500 Hz, which indicates a satisfactory sound absorption effect. The nonwoven fabric/spacer fabric/PU foam sandwiches proposed in this study are mechanically strong, sound absorbent, and fire retardant, and can be used in construction material and electromagnetic shielding composites.  相似文献   

19.
Bio-materials have ignited a quest among research fraternity to be used in every possible field of applications like automobile, sports, medical, civil and textile industry. Application spectrum of natural fiber reinforced polymer composites is spreading globally in every field of engineering having structural and tribological applications. The present work investigates the tribological performance of regionally available inexpensive plant based natural fiber reinforced polymer composites. In this work, three different types of natural fibers (jute, hemp, and flax) were reinforced with epoxy matrix to fabricate natural fiber reinforced polymer composites (NFRP) and their hybrid composites (jute/hemp/Epoxy, hemp/flax/epoxy and jute/ hemp/flax/epoxy) using hand-layup technique. Tribological performance of the developed bio-composites were evaluated in terms of frictional characteristics and sliding wear under dry contact condition at different process parameters, such as applied load (10-50 N), sliding speed (1-5 m/s) and sliding distance (1000-2000 m). Experimental results of wear analysis confirmed that incorporation of natural fibers into epoxy polymer matrix significantly improved the wear behavior of the developed NFRP composites in comparison to neat epoxy polymer. Among all the developed composites, jute/epoxy composite achieved the highest coefficient of friction, frictional force and specific wear rate. Dynamic mechanical analysis (DMA) was also analyzed to evaluate the viscoelastic behavior of the developed composites. The surface morphology of samples after wear test was examined by scanning electron microscopy to investigate and propose the possible wear mechanism of the developed composites.  相似文献   

20.
超高产型杂交红麻中杂红305的选育   总被引：4，自引：1，他引：4  
李德芳  陈安国 《中国麻业》2005,27(5):221-226
中杂红305（原名“H305”）系利用外观性状茎色、叶型相似、经济性状互补性强的红麻良种为亲本,从数十个组合中筛选出杂种F1、F2代均可利用的超高产型抗病优质杂交组合。在入选的杂交红麻杂优组合F1、F2代的杂种组合比较中,杂优组合的一、二代的优势是显著的。在比较试验中,其中超高产型杂优组合H305F2分别比KB2、74—3增产23．97％、33．47％,达极显著水平,居首位。在1999—2000年全国红麻区域试验中,H305（F2）平均纤维产量3691．5kg／hm^2,比对照红引135平均增产22．1％,居首位,较对照和其它参试新品种增产显著。平均干茎产量20289kg／hm^2,较对照增产26．5％,表现出植株高大,皮较厚,有效株数多,干茎产量和出麻率均高,抗病性强,纤维品质好,纤维品质经农业部麻类产品质量监督检验测试中心检测,纤维支数289支,强力474牛顿,优于对照品种。采用硫酸盐法制浆,H305的平均干茎纸浆得率为47．9％,高于对照。人工接茵炭疽病鉴定,病情指数为23．5,烂头率为1．8％,属于高抗类型。表明中杂红H305是高产、优质、多抗、适应性广的纺织、造纸兼用的红麻新组合。红麻超高产型杂种二代的利用可大大降低种子成本,不仅红麻杂种优势的利用在生产上大面积推广应用成为可能,而且可显著提高麻农的经济效益和社会效益,其前景非常广阔。  相似文献   

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