不同配方木塑复合材料的力学性能比较与分析

测试了四种配方木塑复合材料的力学性能,包括弹性模量、弯曲强度和抗压强度,并对其结果进行了简要的分析.实验结果表明,四种配方生产的材料力学性能都较为优异,都能符合户外装饰板材的要求.     

改性剂对高模量沥青混凝土水稳定性影响研究

指出高模量沥青混凝土(HMAC)具有优异的抗车辙性能,但是其水稳定性受改性剂影响很大,通过残留稳定度和冻融劈裂强度试验,测试两种不同的改性剂及掺量的HMAC的水稳定性,研究了HMAC的水稳定性受改性剂种类及掺量影响的规律,为HMAC的设计提供一定的理论依据。     

聚酯仿真丝纤维的丝鸣化处理及其工艺

对聚酯仿真丝纤维的丝鸣化处理进行了探讨,取得以下结果:(1)制备了具有较好发声效果的聚酯纤维丝鸣处理液;(2)制订了相应的工艺措施以提高丝鸣处理效果的耐水洗性能;(3)在同样的处理条件下,模量较低、纤度较小的异形CDPET纤维(阳离子可染聚酯纤维)具有较好的发声效果.     

水轮机过流部件磨蚀机理的研究

分析了水轮机过渡部件磨蚀的特点,总结出过流部件的磨蚀主要是冲蚀磨损,气蚀破坏及它们的联合作用。决定冲磨损的关键因素是材料的弹性模量,影响气蚀破坏的主要因素是材料的硬度,提出了提高过流部件抗磨蚀性能的方法。     

基于Hermite插值的小波模极大值重构滤波的肌电信号消噪方法

为了消除混杂在肌电信号中的噪声,该文提出了基于Hermite插值的小波模极大值重构滤波的肌电信号消噪方法。该方法先对肌电信号进行小波分解;其次,根据小波系数的奇异性,利用信号与噪声模极大值在小波尺度上的不同变化特性,分离出信号与噪声;再次,用Hermite插值法重构小波系数;最后从重构的小波系数恢复成去噪后的信号。实验结果表明,Hermite插值的小波模极大值重构能有效地去除噪声,提高信噪比,且保留了肌电信号的细节信息,为肌电信号的特征提取和模式识别创造了良好的条件。     

The influence of indenter bluntness on the apparent contact stiffness of thin coatings

In the present paper, the influence of punch tip sharpness on the interpretation of indentation measurements is considered.Firstly, in order to obtain analytical insight into the nature of the problem, closed form solutions are presented for the indentation of a homogeneous elastic half-space by an axisymmetric indenter of arbitrary shape, including Hertzian, conical, and conical indenter with a rounded tip.Next, a fast and efficient numerical implementation of a semi-analytical approach to the solution of problems about frictionless axisymmetric indentation of an elastic layer on a dissimilar substrate is described. The approach allows rapid determination of the load-displacement curves for an arbitrary punch shape.The aim of the study was to explore the implications of a finite indenter tip radius for the problem of property identification of thin films. The variation of the apparent substrate stiffness with indentation depth was established for several generic indenter shapes, namely for flat, conical and parabolic punches, and for a conical punch with a rounded tip. It is demonstrated that in each of these cases the depth variation can be described by a simple curve belonging to a family of two-parametric functions. On the basis of these findings we assess the efficiency of using different punch shapes for property determination. A procedure is proposed for this purpose which relies on the use of the depth variation profiles established here. Finally, the influence of imperfect punch shape on the accuracy of analysis is considered.     

Molecular Dynamics Simulations of Polymer‐Bonded Explosives (PBXs): Modeling,Mechanical Properties and their Dependence on Temperatures and Concentrations of Binders

Two models, i.e. “covering” and “cutting” models, for the polymer‐bonded explosives (PBXs) were proposed for different researching aspects. Used for choosing polymeric binders, the “covering” models are mainly applied to find the relations of temperatures and concentrations respectively with elastic properties of the PBXs. The “cutting” model is especially used to describe the highly anisotropic behavior of 1,3,5‐triamino‐2,4,6‐trinitrobenzene crystals (TATB). These models were realized by using molecular dynamics methods. It is found that the ductility of crystalline TATB can be effectively improved by blending fluorine‐containing polymers in small amounts. The moduli for the PBXs decrease with increase in temperature and concentration of binders. Different crystalline surfaces interacting with the same polymer binder have different modulus‐decreasing effects due to the highly anisotropic behavior of TATB. The modulus‐decreasing effect for different crystalline surfaces ranking order is (010)≈(100)>(001).     

Quality Evaluation of RDX Crystalline Particles by Confined Quasi‐Static Compression Method

A confined, quasi‐static uniaxial compression method, named as the compressive stiffness test (CST), is promoted to evaluate the quality of different RDX crystalline particles which are obtained from commercial and reprocessed lots. This method is based on the fact that the fragmentation or fracture behavior in the compression process could be correlated to the external/internal defects of targeted crystalline particles. The quality difference between the commonly used RDX and reprocessed RDX can be easily discriminated by compaction curves and the defined initial secant modulus can be used as a quantitative parameter to grade RDX particles. The results show that the RDX recrystallized from mixed solvents and spheroidized by treatment with solvent is of much higher quality than the commonly used RDX, and the particle size as well as external characteristics exert limited effects on the compaction curves, but the key factor is internal defects, which affect the coherence strength of RDX crystalline particles. Qualitative optical image analysis and quantitative particle apparent density measurements by liquid density gradient tubes also give consistent results with those from the CST.     

探讨一种凸轮理论曲线的通用方程式

凸轮机构可以实现各种复杂的运动要求,随着加工技术的进步,数控机床加工凸轮逐渐普及,用数字来描述凸轮曲线,推导过程复杂、编程工作量大。本文利用不同位置摆动从动件凸轮机构之间的联系,归纳出了3个反映机构不同位置的系数,利用3个系数各两种状态的8种组合,推导了各种滚子摆动从动件盘形凸轮理论曲线的方程式,总结出各种滚子摆动从动件盘形凸轮理论曲线的通用方程式,缩短了凸轮设计的周期。     

岩石中应力弛豫的衰减和模量色散

本文在低频和声频范围内研究了砂岩、大理岩及花岗岩在不同饱和液体情况下的衰减和模量随温度的变化，同时还探讨了衰减与激发频率、共振振幅的关系。并根据时温等效原理，得出了饱和原油砂岩在衰减～温度港上28℃的衰减峰应该与衰减～频率港上8．9HZ的衰减峰相对应的结论。