DELAMINATION FORMATION AND DELAMINATION PROPAGATION OF COMPOSITE LAMINATES UNDER COMPRESSIVE FATIGUE LOADING

Fatigue tests of the smooth composite laminates and the notched composite laminates under compressive cyclic loading have been carried out. The damage mechanism is discussed and analyzed. Damage evolution is monitored using stiffness decay. From these tests, it is found that the initial delamination occurs at the free boundary of smooth specimens, or the notch boundary of notched specimens, subjected to the compression-compression cyclic load. A point of view in relation to two-phases of compression fatigue delamination of composites is proposed, namely, compression-compression delamination consists of the delamination formation phase and the delamination propagation, and there is a 'damage transition point' to separate this two-phases. Furthermore, an empirical modulus degradation formula and its parameters fitting method are presented. According to the test data handling results, it is shown that this formula is univocal and can fit the test data conveniently. In addition, two kinds of new anti-buckling devices are designed for these tests. At last, the E-N curves, the D-N curves and the S-N curve of the smooth carbon fiber reinforced composite laminates of T300/648C are determined to predict the fatigue life of the notched composite laminate. And the E-N curve of the notched specimens at the given load ratio R = 10 and minimum load Pmin = -0.45 kN is also measured to verify the estimated result of fatigue life.

Impregnated Paper-Based Decorative Laminates Prepared from Lignin-Substituted Phenolic Resins

High Pressure Laminates(HPL)panels consist of stacks of self-gluing paper sheets soaked with phenol-formaldehyde(PF)resins.An important requirement for such PFs is that they must rapidly penetrate and saturate the paper pores.Partially substituting phenol with bio-based phenolic chemicals like lignin changes the physico-chemical properties of the resin and affects its ability to penetrate the paper.In this study,PF formulations containing different proportions of lignosulfonate and kraft lignin were used to prepare paper-based laminates.The penetration of a Kraft paper sheet was characterized by a recently introduced,new device measuring the conductivity between both sides of the paper sheet after a drop of resin was placed on the surface and allowed to penetrate the sheet.The main target value measured was the time required for a specific resin to completely penetrate the defined paper sample(“penetration time”).This penetration time generally depends on the molecular weight distribution,the flow behavior and the polarity of the resin which in turn are dependent on the manufacturing conditions of the resin.In the present study,the influences of the three process factors:(1)type of lignin material used for substitution,(2)lignin modification by phenolation and(3)degree of phenol substitution on the penetration times of various lignin-phenolic hybrid impregnation resins were studied using a complete twolevel three-factorial experimental design.Thin laminates made with the resins diluted in methanol were mechanically tested in terms of tensile and flexural strains,and their cross-sections were studied by light microscopy.

Xiongxian Huajiang Paper Plastic Package Co., Ltd.

Company Introduction: Xiongxian Huajiang Paper Plastic Package Co., Ltd. engaged in variety of flexible package. Our head office is located in Xiongan New Area of Hebei Province where is the most hopeful place in China for the next thousand years, it is the new developing focus in China. We have got the most convenient transportation, our factory is only 47 miles from Beijing, and 110 mils from the port of Xingang.

Converting of MSW into Valuable Hydrocarbons by Pyrolysis： Effect of Paper/Plastic Ratio and Reaction Time

Municipal solid wastes from industrial plants were pyrolyzed in a fixed bed reactor to evaluate the influence of paper/plastic ratio and reaction time both on product quantity and quality. Raw materials have been pyrolyzed under nitrogen in a 3.0 dm^3 autoclave. Results show considerable differences in yields and quality of products obtained by pyrolysis of wastes with different paper content. Light and heavy oils were mixtures of organic compounds containing valuable hydrocarbons and oxygenated chemicals, while chars were rather composed of inorganic compounds from the raw materials. Longer reaction time of pyrolysis had produced higher non-condensable gas, water and light oil. Gases contained CO, CO2 and hydrocarbons, but the concentrations were very function of reaction time and paper/plastic ratio. Light and heavy oils showed similarities with middle distillates and heavy oils in refinery, the high paper content of the raw materials was unfavourable for longer storage of waste derived oils.

Progressive Analysis of Bearing Failure in Pin-Loaded Composite Laminates Using an Elasto-Plastic Damage Model

Bearing failure of composite laminate is very complicated due to the complexity of different failure mechanisms and their interactions. In this paper, an elasto-plastic damage model is built up to describe the process of failure in composite laminates subjected to bearing load. Non-linear behavior of composite before failure is taken into consideration by using a modified Sun-Chen one parameter plasticity model. LaRC05 failure criteria are employed to predict the initiation of failure and the evolution of failure is described by a CDM based stiffness degradation model. Both theory and some application issues like parameter determination are discussed according to phenomenon of experiments. The model is firstly validated by several experiment results of unidirectional laminate and then applicated into the progressive analysis of bearing failure in pin-loaded multidirectional laminates, both intralaminar and interlaminar damage are taken into consideration. The result of finite element analysis is compared with experiment results;it shows good agreements in both mechanical response and progress of failure, so the model can be evaluated to be effective and practical in bearing failure analysis of composite laminates.

A FATIGUE FAILURE CRITERION OF NOTCHED GFRP LAMINATES

A fatigue failure criterion for predicting the fatigue life of notched orthotropic fiber reinforced plasties (FRP) plates based on the concept of stress field intensity (SFI) near the notch root is subjected to further experiments. The investigation is accomplished by obtaining experimental data on the notched specimens of glass fiber reinforced plastics (GFRP) with edged notches under tension tension cyclic loading. The process of initiation and growth of fatigue damage near the notch root is measured by means of the optic system with a computer controlled display (CCD) camera. The experimental results show that the number of loading cycles required to initiate fatigue damage is governed by the stress field intensity.

Downregulation of caveolin-1 contributes to the synaptic plasticity deficit in the hippocampus of aged rats

Caveolin-1 is involved in the regulation of synaptic plasticity, but the relationship between its ex-pression and cognitive function during aging remains controversial. To explore the relationship be-tween synaptic plasticity in the aging process and changes in learning and memory, we examined caveolin-1 expression in the hippocampus, cortex and cerebellum of rats at different ages. We also examined the relationship between the expression of caveolin-1 and synaptophysin, a marker of synaptic plasticity. Hippocampal caveolin-1 and synaptophysin expression in aged （22-24 month old） rats was significantly lower than that in young （1 month old） and adult （4 months old） rats. Ex- pression levels of both proteins were significantly greater in the cortex of aged rats than in that of young or adult rats, and levels were similar between the three age groups in the cerebellum. Linear regression analysis revealed that hippocampal expression of synaptophysin was associated with memory and learning abilities. Moreover, synaptophysin expression correlated positively with caveolin-1 expression in the hippocampus, cortex and cerebellum. These results confirm that caveolin-1 has a regulatory effect on synaptic plasticity, and suggest that the downregulation of hippocampal caveolin-1 expression causes a decrease in synaptic plasticity during physiological aging.

Correlation between the cumulative analgesic effect of electroacupuncture intervention and synaptic plasticity of hypothalamic paraventricular nucleus neurons in rats with sciatica

In the present study, a rat model of chronic neuropathic pain was established by ligation of the sciatic nerve and a model of learning and memory impairment was established by ovariectomy to investigate the analgesic effect of repeated electroacupuncture stimulation at bilateral Zusanfi （ST36） and Yanglingquan （GB34）. In addition, associated synaptic changes in neurons in the paraventricular nucleus of the hypothalamus were examined. Results indicate that the thermal pain threshold （paw withdrawal latency） was significantly increased in rats subjected to 2-week electroacupuncture intervention compared with 2-day electroacupuncture, but the analgesic effect was weakened remarkably in ovariectomized rats with chronic constrictive injury. 2-week electroacupuncture intervention substantially reversed the chronic constrictive injury-induced increase in the synaptic cleft width and thinning of the postsynaptic density. These findings indicate that repeated electroacupuncture at bilateral Zusanfi and Yanglingquan has a cumulative analgesic effect and can effectively relieve chronic neuropathic pain by remodeling the synaptic structure of the hypothalamic paraventricular nucleus.

Treadmill step training promotes spinal cord neural plasticity after incomplete spinal cord injury

A large body of evidence shows that spinal circuits are significantly affected by training, and that intrinsic circuits that drive locomotor tasks are located in lumbosacral spinal segments in rats with complete spinal cord transection. However, after incomplete lesions, the effect of treadmil training has been debated, which is likely because of the difficulty of separating spontaneous stepping from specific training-induced effects. In this study, rats with moderate spinal cord contusion were sub-jected to either step training on a treadmil or used in the model （control） group. The treadmil training began at day 7 post-injury and lasted 20 ± 10 minutes per day, 5 days per week for 10 weeks. The speed of the treadmil was set to 3 m/min and was increased on a daily basis according to the tolerance of each rat. After 3 weeks of step training, the step training group exhibited a sig-nificantly greater improvement in the Basso, Beattie and Bresnahan score than the model group. The expression of growth-associated protein-43 in the spinal cord lesion site and the number of tyrosine hydroxylase-positive ventral neurons in the second lumbar spinal segment were greater in the step training group than in the model group at 11 weeks post-injury, while the levels of brain-derived neurotrophic factor protein in the spinal cord lesion site showed no difference between the two groups. These results suggest that treadmil training significantly improves functional re-covery and neural plasticity after incomplete spinal cord injury.

Plasticity of language pathways in patients with low-grade glioma A diffusion tensor imaging study

Knowledge of the plasticity of language pathways neurosurgeons to achieve maximum resection wh n patients with low-grade glioma is important for e preserving neurological function. The current study sought to investigate changes in the ventral language pathways in patients with low-grade glioma located in regions likely to affect the dorsal language pathways. The results revealed no significant difference in fractional anisotropy values in the arcuate fasciculus between groups or between hemispheres. However, fractional anisotropy and lateralization index values in the left inferior longitudinal fasciculus and lateralization index values in the left inferior fronto-occpital fasciculus were higher in patients than in healthy subjects. These results indicate plasticity of language pathways in patients with low-grade glioma. The ventral language pathways may perform more functions in patients than in healthy subjects. As such, it is important to protect the ventral language pathways intraoperatively.

Thermogravimetric and Synergy Analysis of the Co-Pyrolysis of Coconut Husk and Laminated Plastic Packaging for Biofuel Production

Unlike plastic,biomass can also be converted and produce high quality of biofuel.Co-pyrolysis of coconut husk(CH)and laminated plastic packaging(LPP)were done in this study.Synergy between these two feedstock was calculated by using thermogravimetric(TGA)and derivative thermogravimetry(DTG)analysis.Different activation energies of the reactions in the co-pyrolysis of CH and LPP were evaluated using the Coats-Redfern method.Results showed an activation energy ranging from 8 to 37 kJ/mol in the different percentage composition of the co-pyrolysis.Also,thermal degradation happens in two-stages in the copyrolysis of CH and LPP,in which CH degrades at the temperature range of 210℃ to 390℃ while LPP degrades in temperatures 400℃-600℃.Co-pyrolysis of CH and LPP can be an alternative for biofuel production and can also reduce the waste problems in the community.

Research State of Disposable Nonplastic Straws

The continuous production of disposable plastic straw places a high demand on global petrochemical resources and a significant environmental burden.Biodegradable and eco-friendly straws have therefore been studied and produced worldwide.This article briefly introduces the characteristics of paper straws and polylactic acid(PLA)straws,and focuses on edible straws made using,e.g.,hydrophilic colloids,zein,and starch.Raw-material selection,preparation methods,advantages,and defects of straws are summarized,to provide a reference for the development and research of eco-friendly straws.

Detection of stacking orientation error of CFRP composite laminates using ultrasound waves

A jig was developed for generating a shear wave. A pyramid with an isosceles triangle with two 45o was made of aluminum to generate shear waves using two longitudinal transducers based on ultrasonic-polarized mechanism. Also, the signal splitter was connected to the pulser jack on the pulser/receiver and to the longitudinal transducers. Therefore, an experimental way was performed in order to make shear wave on the bottom of aluminum alloyed pyramid. Also, a jig was manufactured and developed for generating a shear wave based on the computer numerical simulation. It is found that the experimentally shear wave variation of newly-designed jig is consistent with computer numerical simulation results and shear wave ultrasonic application can be very useful to detect the defects in CFRP composites.

建筑建材领域“以竹代塑”工程材料研究现状与发展趋势

随着全球对可持续发展的关注,建筑行业面临着传统建材带来的环境问题。塑料作为一种广泛使用的建筑材料,虽然具备良好的物理特性,但其不可降解性对环境造成了重大影响。竹材作为一种快速再生资源,具有优良的力学性能和环境友好特性,以竹材为基础的“以竹代塑”工程材料逐渐成为研究和应用的热点,展现出良好的环保性能与经济价值。聚焦于“以竹代塑”工程材料作为传统塑料替代品的优势和潜力,综述了当前建筑建材领域“以竹代塑”工程材料的研究现状,包括材料分类、制备工艺、改性技术和实际应用,系统分析了“以竹代塑”工程材料在建筑建材领域的应用必要性,探讨了“以竹代塑”工程材料的制备工艺与改进方向,并通过国内外研究现状分析,提出“以竹代塑”工程材料目前存在的主要问题及发展建议。研究表明,“以竹代塑”工程材料在强度、耐久性等方面展现出良好性能,不仅能够有效替代传统塑料建材,还可以降低建筑行业的碳排放,推动绿色建筑发展,目前已成功应用于生态建筑等领域。然而,现阶段相关标准和规范尚不完善,市场推广不足。对“以竹代塑”工程材料在建筑建材领域的应用研究现状进行系统综述,旨在为竹材在工程结构行业的推广应用提供理论支持。未来,随着技术创新、市场需求的增加以及政策支持的强化,“以竹代塑”工程材料有望在建筑建材领域中获得更广泛的应用。

基于纸包装生物基涂层的研究进展

随着人们环保意识的逐渐提高,环保友好、节能减排已成为全球人们关注的重点,在限塑令、禁塑令背景下,以纸代塑是实现环境保护和可持续发展的主要方式。但由于纸基材料表面疏松多孔的结构,小分子的水和气体很容易通过孔隙渗透和润湿纤维,不能满足包装材料的阻隔功能要求,同时纸张没有热封性能,无法通过加热自粘制袋的方式达到工业化生产的要求,且其在机械强度方面难以与塑料相媲美。本文主要从防潮性、阻气性、热封性和机械强度四个角度综述了生物基涂层改性纸基包装材料的研究。

板式橡胶支座梁式桥准隔震体系参数组合研究

目的提出纵横桥向分别设置X型弹塑性钢挡块、黏滞阻尼器与板式橡胶支座进行组合的方法,形成板式橡胶支座梁式桥准隔震体系来提高桥梁的抗震性能,克服采用板式橡胶支座的梁式桥限位能力、自复位能力不足等缺陷。方法应用OpenSees有限元软件建立一座四跨连续梁桥全桥精细化模型,通过主梁位移、桥墩内力、支座剪力与位移等地震响应对X型弹塑性钢挡块和黏滞阻尼器进行了力学性能参数分析。结果横桥向X型弹塑性钢挡块与板式橡胶支座的组合可以有效控制梁体在地震作用下的位移,基本消除震后残余位移,且在合理选择挡块力学性能参数的情况下,能够有效降低支座承受的剪力与位移,同时减小传递到桥梁下部结构的惯性力以起到保护作用;纵桥向黏滞阻尼器和板式橡胶支座的组合,采用较为合理的参数选择可以一定程度上减小梁端的最大位移和残余位移,且大大降低了墩柱所承受的内力,确保桥梁下部结构免受严重损伤。结论板式橡胶支座与X型弹塑性钢挡块、黏滞阻尼器组合形成的板式橡胶支座梁式桥准隔震体系能够有效提高桥梁的抗震性能,解决强震作用下梁体位移过大的问题。

微波加热下生活废纸和PE塑料共热解产气特性

以可燃生活垃圾中的主要成分——生活废纸和聚乙烯(polyethylene,PE)塑料为原料,采用微波加热,对纸张/PE共热解中产气释放过程、产气成分和产气率等特性的影响规律进行研究。实验结果表明:在600℃热解终温下,产气成分以CO、CO_(2)为主,约为35%~40%,其次为CH_(4)、H_(2),其他气体含量较低。随着微波功率的增加,热解产气各成分的产量都明显增加,且各产气析出温度及峰值温度向高温方向移动。随着物料中PE的混合比例增加,纸张/PE共热解产气率降低明显,焦油产率则明显增加,表明PE热解产物以焦油为主。在定热解终温的情况下,添加热解碳对热解产气成分的体积分数影响不大,但可有效提高热解产气量。

乡村振兴背景下邳州纸塑狮子头传承创新模式探索

邳州纸塑狮子头是一种综合的民间造型艺术,主要用于民间舞狮表演,它与邳州民间泥塑、民间绘画、民间舞蹈等民间艺术根脉相连,极具苏北地方特色。由于近代传承环境的消失,承载狮头文化的传统乡会舞狮受到冲击,逐渐衰退,进而狮头文化也日渐淡出民众视野。本文在乡村振兴战略背景下,提炼邳州纸塑狮子头的独特价值,对其生存困境进行分析归纳,探索发展新路径。梳理出可复制可推广的典型做法,形成“传文化·承未来·创融合·新影响”的传承创新模式,助力乡村振兴取得新进展。

纸代塑涂层技术在环保食品包装领域的应用研究

在环保理念指引下,纸质包装因其可循环再利用特性,正逐步成为首选。其独特的材料特性为包装设计提供了丰富的创新空间,不仅增强了包装的视觉吸引力,还实现了实用性与审美性的融合。面对传统纸质包装的局限性,可采用先进的纸代塑涂层技术,研发出新型环保包装材料。这种材料不但符合物理和食品安全标准,而且省去了多层复合工艺,实现了无氟、无塑的环保目标,具备易回收和可降解的特点,标志着包装材料领域的一大进步。

高透明度、高雾度塑料纸在有机发光器件中的应用及其性能提升

随着柔性电子行业的发展,传统的PET、PEN等塑料衬底由于成本更高,光取出效率低下等问题已经无法满足人们的需求.纸张由于其获取途径广泛,成本低廉,更加轻薄是一种前景广阔的柔性衬底.通过浸渍涂布工艺,将环氧树脂与硫酸纸进行结合,制备了一种新的基材,即塑料纸.通过测试发现,塑料纸具有优异的光学性能、机械性能以及水和化学稳定.研究结果表明,通过环氧树脂涂布处理后,不仅提高了纸张表面的平整性,而且改善了纸张的润湿性.制备出的塑料纸光透过率高达88.25%,达到与PET基材同一水平,并且塑料纸的雾度达到62.9%,远远高于PET基材.塑料纸的拉伸强度为108.4 MPa,还兼具良好的水和化学稳定性.在大气环境下,基于发光电化池(LEC)的原理,成功地在塑料纸表面制备出有机发光器件,并实现均匀地发光.该器件的最大亮度为396.2 cd m^(-2),最大电流效率为0.64 cd A-1,是PET衬底的2.9倍,具有更加优异的光电性能.所研制的高透光率、高光雾度的塑料纸在柔性光电器件中具有很大的应用潜力.