小兴安岭几个主要树种的蠕变特性

本文是根据短时间的木材弯曲蠕变实验对小兴安岭的几种主要树种木材的粘弹性模型元件数和元件常数进行了确定。用来描绘木材弯曲蠕变的粘弹性模型都是由一个马克思维尔体和两个开尔文体所组成的六元件模型。 研究结果得知J_0>J_1>J_2,且J_2:J_1与η_2:η_1前者比后者显著的低,而J_1:J_0与η_1:η_0之比后者显著的高。另外还得知树种不同,粘弹性常数具有很大差异,从而决定了各自抵抗蠕变的能力。 用此种实验方法来确定粘弹性模型的元件数和元件常数,其拟合度较高,是一种行之有效的方法。因此可认为在木材物性研究和在粘弹性状态的预测中,采用粘弹性模型元件常数,就将和力学性质中的常数一样表示蠕变度量。这对木材的物性研究和工程应用提供了可靠的参数。     

掺硅粉水泥与硅质集料界面结构的初步探讨

通过一系列实验数据和曲线说明,掺硅粉水泥与集料的界面结构有所变化,并闸述了变化的原因。实验结果表明:掺硅粉水泥与集料胶结的粘结强度高于硅酸盐水泥与集料胶结的粘结强度;界面区的最薄弱层并不在界面表层,而是在距界面十几微米处。     

基于仿真技术的发动机曲轴轻量化设计及评价

在曲轴的轻量化设计中,首先根据客观条件找出曲轴的减质量方案,然后设定减质量部位结构尺寸的范围,最后通过工程分析软件对不同状态的曲轴进行分析,从而找出满足设计要求的最轻状态曲轴。     

Using instrumented bulldozers to map spatial variation in the strength of regolith for bauxite mine floor rehabilitation

The high strength of some regolith types can limit the growth of rehabilitated jarrah forest following bauxite mining in southwest Australia. Ripping mine floors to a depth of 1.5 m alleviates high strength zones and improves root exploration of substrates. Understanding the variability of regolith strength at the mine pit scale may be useful for improving site-specific ripping and reducing rehabilitation costs. Regolith strength maps were developed based on real-time, field measurement of the hydraulic fluid pressure in the tilt cylinders of Komatsu 475 and Caterpillar D11R bulldozers operating at an average speed of 0.8 ms⁻¹ with standard tip, single shank deep-ripping tines. The strength maps rank regolith into strength classes and show positions of low-, medium-, high- and extreme strength zones in the floors of former opencast bauxite mines. Maps were evaluated using strength measurements on excavated regolith profiles revealing a reliable relationship between bulldozer-mapped regolith strength and actual regolith strength. Weighted unconfined compression strength for mine floor materials within a regolith profile can be grouped as follows: saprolite <4000 kN/m²; quartz-rich, sandy clay (Zm) and silty clay (Zp) 1000–4000 kN/m²; ferruginous/gibbsitic (cemented) material (Zh) 4000–8000 kN/m²; and granite or dolerite rock and hard saprock 5000–14,000 kN/m². Ripper hydraulic pressure was linearly related to the weighted unconfined compression strength (kN/m²) of classified regolith profiles (r² = +0.47). The instrumented bulldozer mapping technique can partly distinguish between classified regolith types, particularly granite and granitic saprock (>75 bar) and dolerite and doleritic saprock (25–75 bar). Some regolith types including: quartz-rich, sandy clay; silty clay; and soft saprolite have low bulldozer-measured strength (25 bar) and are indistinguishable by the bulldozer. Regolith strength maps may improve the targeting of secondary contour ripping to parts of a mine floor where it is most-needed.     

脲醛树脂稻壳板平面抗拉强度的研究

脲醛树脂压制的稻壳板主要问题是平面抗拉强度低。从组成脲醛树脂的成分、树脂特性、增强剂及固化剂等几方面研究了稻壳板的平面抗拉强度。研究结果表明,采用适合稻壳特点的脲醛树脂并在适当增强剂和固化剂的配合下,可大幅度提高稻壳板的平面抗拉强度,即使施加较抵的胶量,稻壳板的平面抗拉强度仍然达到标准。     

基于有限元强度折减法的边坡在不同工况下的安全状态分析

使用ANSYS软件,对边坡进行二维建模,采用二维有限元强度折减法对不同工况下边坡的进行安全稳定性分析.当有限元计算的数值不再收敛时,边坡处于临界状态,此时的折减系数(F,值)即作为边坡稳定安全系数K.计算得出各种工况下的安全稳定系数,进而对边坡的稳定情况做进一步分析.结果采用有限元强度折减法求得的边坡安全系数与传统的刚体极限平衡法求出的结果近似.     

水电站边坡滑面强度参数反演

该边坡为大坝建设区安全、稳定性要求最高的边坡,其整体稳定性直接影响到坝段的成立,对坝址的选择具有决定性的影响.对该区域的地质、水文资料的观测推测该边坡整体上不稳定,在现有资料的分析基础上,判断该边坡可能的破坏模式为覆盖层内部的滑动和沿基覆界面的深层滑动.基于现场量测结果和边坡安全系数的计算方法,对边坡的土体力学强度参数进行安全参数反演分析.     

Tensile properties for netting materials used in aquaculture net cages

In order to perform a strength analysis of a net cage, it is crucial to know the tensile stiffness properties of the netting material. A new method for testing was established in order to determine the tensile properties of knotless netting materials. We applied it to a variety of netting materials and developed stress–strain relations. The stiffness was expressed as a constant value for relatively small strains, while for large strains the stress–strain relation was defined by a third degree polynomial. The average value of the constant stiffness for the tested wet netting materials was 81 N mm⁻² with a standard deviation of 9 N mm⁻² for strains less than 10%. For netting materials treated with anti-fouling paint, the average constant stiffness value was 131 N mm⁻² with a standard deviation of 13 N mm⁻² for strains less than 30%. The results are valid for uniaxial static loading of netting.     

新型竹质复合板的研究(Ⅰ)

本文对利用小径级毛竹,采用不去竹青、竹黄的新工艺制造的竹-竹、竹-木复合胶合板作了研究,结果表明:对竹青、竹黄进行喷砂处理后而制成的竹胶板,具有非常高的强度。     

301国道水泥混凝土路面滑模摊铺配合比设计

采用室内试验并结合以往的施工实践，进行了水泥混凝土路面滑模摊铺配合比设计。试验通过多次调配．根据各项试验结果，按照满足强度、工作性、耐久性、经济性的原则，找出最佳配比，为生产配合比提供依据。