玻璃钢筋混凝土的有限元计算与试验

钢筋混凝土广泛应用于土木工程领域，但其结构耐久性因钢筋本身的锈蚀成为现今急待解决的问题。人们一直在寻找对钢筋混凝土进行改良的途径，用玻璃钢筋代替普通钢筋是解决这一问题的一个有效的方法，为此进行了试验和ANSYS有限元分析，结果证明此法具有可行性。     

甲基丙烯酸锌在NBR／木质素中的应用

研究了α－甲基丙烯酸锌（ＭＡＡ－Ｚｎ）对ＮＢＲ／木质素（１００／１００，质量比）硫化胶性能的影响。结果表明，加入１．５～５．０份ＭＡＡ－Ｚｎ，可提高硫化胺的１００％的定伸应力，硬度和抗压缩永久变形能力，但对其他力学性能影响甚微，经分析可知，ＭＡＡ－Ｚｎ还可以降低硫化反应活化能，提高硫化胶的交联密度和耐热老化性能。     

Preparation and characterization of calcium carbonate/low‐density‐polyethylene nanocomposites

Calcium carbonate/low‐density‐polyethylene (LDPE) nanocomposites have been prepared by melting blend with twin‐screw extruder. The mechanical properties of composites and the dispersion of the nanoparticles were studied. The reinforcement mechanism was discussed. The results show that not only the tensile property but also the flexural modulus of the system have been evidently increased by the addition of calcium carbonate. The calcium carbonate particles have been dispersed in the matrix in the nanometer scale. The reinforcement mechanism of the calcium carbonate lies on that the calcium carbonate particles, acting as hetero‐nuclei, can induce higher crystallinity at the matrix‐particle interface compared to regions away from the interface. Consequently, in the process of the tensile test, the nanocomposites have better tensile yield strength. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

玻璃纤维增强热塑性塑料的发展概况

根据玻璃纤维增强热塑性塑料的发展过程分别介绍了短纤维增强热塑性塑料、玻璃纤维毡增强热塑性塑料、玻璃纤维/热塑性塑料复合纤维、长纤维增强热塑性塑料和热塑性拉挤产品的制造方法、特性和应用。     

A comparison of bending strength between adhesive and steel reinforced concrete with steel only reinforced concrete

Cracking of brittle cementitious composites subjected to excessive loading causes a potential reduction in material performance. Steel bars or metal fibers typically act as tensile reinforcing in concrete composites to increase the material's structural capacity in bending and to delay or prevent matrix cracking.The goal of this research is to determine whether the performance in bending strength and material integrity of a typically reinforced cementitious composite may be improved through the release of “healing” chemicals, such as adhesives, from hollow fibers into cracks induced by loading in addition to the metal reinforcing. Adhesive-filled repair fibers are intended to break immediately upon cracking in the concrete thereby activating the healing process with the release of a sealing or adhering substance. This self-repair occurs whenever and wherever cracks are generated.     

自重施加方式对高拱坝廊道结构应力及配筋的影响

自重工况一般是高拱坝内廊道配筋设计的控制工况,由于高拱坝施工过程的特殊性及复杂性,有限元计算中自重有多种施加方式。结合工程实例,对高拱坝基础廊道结构进行三维有限元分析,比较不同自重施加方式对廊道结构应力及配筋的影响。研究结果表明:按整体自重考虑时,廊道结构应力及配筋面积明显偏小;全部按分缝自重考虑时,廊道结构应力及配筋面积明显大于按施工过程考虑自重的结果;为符合实际施工过程及结构承载规律,保证结构安全及经济合理,在拱坝结构的有限元计算中应按照施工过程考虑自重荷载。该研究成果对泄洪孔结构的应力分析也具有参考价值。     

设抗震增强体的桩基础力学特性的原位试验研究

在过去的大地震中,许多桩基础因强烈振动和地基变形而遭受结构性破坏,因而提出一种既可以应用于新建桩基础,也可以应用于现有桩基础的抗震加固方法,即采用地基加固技术在桩基础中设置抗震增强体,以与桩基础的钢筋混凝土承台形成双层抗弯结构。采用等比例模型原位水平载荷试验和振动试验以及开挖检查等方法,对抗震加固的力学特性和构建质量进行加固前后的对比研究,进而证实了该加固方法的有效性和可行性,为同类工程起到了一定的参考意义。     

土体固结粉在软土地基加固中的应用研究

针对上海地区软土地基特点,利用工业废渣为主要原料配制成新型土体固结材料——土体固结粉。通过室内的无侧限抗压强度及XRD试验得出其固化土的强度性能及加固机理;再通过室外原位搅拌桩施工及芯样试验进行分析,研究了土体固结粉在软土地基加固实际工程中的适用性。     

亚麻非织造布的缝合加固及其复合材料成型性研究

亚麻纤维通过针刺工艺加工成非织造布,再经缝合加固后,作为复合材料的增强体,与不饱和聚酯树脂复合,制成亚麻/不饱和聚酯复合材料板材及异型件。利用真空辅助树脂传递模塑法制备出的板材,亚麻纤维和树脂结合较为均匀、充分。模压法形成的亚麻非织造布异型件成型良好,无褶皱与破洞。对板材及异型件拉伸、弯曲及压缩等性能的测试结果表明,板材拉伸强度最大值达58.59MPa,弯曲强度最大值为120.26MPa;采用平行缝合工艺的异型件最大破坏载荷为8.99kN。     

Preparation of cardanol–formaldehyde resins from cashew nut shell liquid for the reinforcement of natural rubber

Natural rubber was reinforced with a high loading of a cardanol–formaldehyde resin prepared from cashew nut shell liquid. Cardanol–formaldehyde resins, both resoles and novolaks, were synthesized from cardanol, which was extracted from cashew nut shells. This was done by the condensation polymerization of cardanol and formaldehyde in the presence of base and acid catalysts. The cardanol–formaldehyde resole with the highest yield (ca. 75%) was prepared with a formaldehyde/cardanol molar ratio of 2.0 at pH 8.0 and 90°C for 8 h. The cardanol–formaldehyde novolak with the highest yield (ca. 80%) was prepared with a formaldehyde/cardanol molar ratio of 0.8 at pH 2.2 and 100°C for 7 h. Fourier transform infrared and ¹³C‐NMR were employed to characterize the chemical structures of the obtained cardanol–formaldehyde resins. The resins were compatible with natural rubber in various formulations. The cured behaviors of natural rubber blended with the cardanol–formaldehyde resole and novolak resins were investigated. The cured behaviors of cardanol–formaldehyde resole and cardanol–formaldehyde novolak samples were different, reflecting differences in their chemical reactivities. Furthermore, the incorporation of cardanol–formaldehyde resins into natural rubber provided significant improvements in mechanical properties such as the hardness, tensile strength, modulus at 100 and 300% elongation, and abrasion resistance. However, the elongation at break and compression set of the blends decreased as expected. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1997–2002, 2007