节理岩体体积节理数Jv的新计算公式

岩体体积节理数Jv的定义,按照《工程岩体分级标准》采用节理间距或频率较为恰当;本文研究了岩体内发育一组、二组、三组贯通性节理的情况下,Jv定义的适宜性,指出节理正交的情况下Jv的适宜性最好,推导出Jv的修正系数为K1=|sin(n1,n2[DD(-1][HT5SS]^[HT][][DD)])||cos(n1×n2,n3[DD(-1][HT5SS]^[HT][][DD)])|,研究表明：节理夹角越小,对Jv的影响越大;通过连通率等效途径,断续节理岩体的Jv计算公式为Jv=K1•∑[DD(][]i[DD)]Si•ni(i3)。运用该公式可实现工程岩体裂隙发育程度的科学评价。     

复合敏化乳化炸药的压力减敏

为了解敏化剂对乳化炸药压力减敏的影响,研究了化学发泡+空心玻璃微球和空心玻璃微球+膨胀珍珠岩2种复合方式分别敏化的乳化炸药压力减敏。依据乳化炸药爆炸冲击波的波峰值,计算了它在水下受到冲击波作用之后的压力减敏度,将复合敏化的乳化炸药与分别用单一敏化剂的乳化炸药压力减敏度作了比较和分析。结果表明,第1种复合方式敏化的乳化炸药压力减敏度介于单一敏化的乳化炸药之间,以10cm受压距离为例,压力减敏度分别为1.000、0.983、0.210;第2种复合敏化的乳化炸药压力减敏度小于单一敏化的乳化炸药,10cm受压距离的压力减敏度分别为0、0.274、0.618。分析认为,敏化剂颗粒或气泡的破损与其微界面周围局部破乳的综合作用是造成乳化炸药压力减敏的主要原因。     

Mode III fracture analysis by Trefftz boundary element method

This paper presents a hybrid Trefftz (HT) boundary element method (BEM) by using two indirect techniques for mode III fracture problems. Two Trefftz complete functions of Laplace equation for normal elements and a special purpose Trefftz function for crack elements are proposed in deriving the Galerkin and the collocation techniques of HT BEM. Then two auxiliary functions are introduced to improve the accuracy of the displacement field near the crack tips, and stress intensity factor (SIF) is evaluated by local crack elements as well. Furthermore, numerical examples are given, including comparisons of the present results with the analytical solution and the other numerical methods, to demonstrate the efficiency for different boundary conditions and to illustrate the convergence influenced by several parameters. It shows that HT BEM by using the Galerkin and the collocation techniques is effective for mode III fracture problems. The project supported by the National Natural Science Foundation of China(10472082). The English text was polished by Keren Wang.     

Identification of Molecular Transport Mechanisms in Micro-Porous Hydrotalcite–Silica Membrane

Hydrotalcite (HT) materials have been known to be able to adsorb \(\hbox {CO}_{2}\) even at high temperature. However, HT has not been made into a micro-porous membrane because of its meso-porous nature. In order to form a micro-porous HT membrane, silica was selected as a host matrix due to its ability to retain its micro-porosity. In this paper, a micro-porous hydrotalcite–silica membrane was formed on a meso-porous \(\upgamma \) -alumina layer supported by a macro-porous \(\upalpha \) -alumina substrate. Most of the micro-porosity determined from nitrogen adsorption measurement was found to be either closed or open but not interconnected, whereas most of the meso-porosity (at ca. 11.2 nm) in the micro-porous membrane was open and interconnected, thereby promoting gas flow. Viscous flow mechanism was observed to dominate transport of gases in macro-porous membrane. Knudsen diffusion dominated transport of gases in meso-porous membrane. On the other hand, surface affinity influenced the transport of carbon dioxide through the micro-porous membrane rather significantly. While permeability of pure hydrogen and carbon dioxide were independent of pressure, the permeability of the gases in the binary mixtures decreased with increasing pressure. Both experiment and simulation demonstrated consistent results.     

Nonlinear analysis of thick plates on an elastic foundation by HT FE with p-extension capabilities

The paper is concerned with the development of hybrid-Trefftz (HT) p-element for nonlinear analysis of Reissner-Mindlin plates resting on an elastic foundation. The foundation may be of Winkler-type or Pasternak-type. Exact solutions of the Lame-Navier equations are used for the in-plane intraelement displacement field and an incremental form of the basic equations is adopted. With the aid of incremental form of these equations, all nonlinear terms may be taken as pseudo-loads. Moreover, some modifications have been made on the nonlinear boundary equations to simplify the ensuing derivation. As a result, the in-plane and out-of-plane equations are uncoupled, and then the derivation for the HT finite element (FE) formulation becomes very simple. The practical efficiency of the new element model has been assessed through several examples.     

新材料敏化的乳化炸药爆炸特性研究

通过水下爆炸与爆破切割实验,研究了新型材料敏化的乳化炸药爆炸能量输出特性。研究结果表明,材料CMLS敏化的乳化炸药相对玻璃微球敏化的乳化炸药在爆炸威力上有了很大的提高。CMLS型乳化炸药采用的是动态敏化技术,在引爆过程中,CMLS受压分解产生气体,从而引入均匀分布的小气泡,达到了敏化的目的。它保证了初始高密度装药,并且避免了由于敏化气泡破坏而造成的半爆和拒爆现象。材料CMLS分解产生的物质是含能基团,参与乳化基质的爆轰反应,因此其总输出能量会大于现有乳化炸药的输出能量。上述结果对新型乳化炸药设计具有指导意义。     

Research on Haar Spectrum in fault diagnosis of rotating machinery

In this paper,Haar Transform(HT)is used in the fault diagnosis of rotatingmachinery,and the“Impulse Sharpness”is presented as a diagnostic index.At present,Fourier Spectrumanalysis is most widely used Compared with FFT,HT is more rapid incomputation and more effective in discrete approximation.It’s very suitable for theextraction of pulses in the signal.However,HT has some shortcomings.It’s greatlyaffected by the starting point and length of the sample.Here,the authors present a methodto improve the stability and comparability of Haar Spectrum.The fault imitating test ofrolling bearing is carried out,and the results obtained have verified the sensitivity of HaarSpectrum and Impulse Index to the fault.     

Mode localization in lateral buckling of partially embedded submarine pipelines

The partially embedded submarine pipelines might buckle laterally at some segments under high pressure and high temperature (HP/HT) conditions. The buckling pattern localization introduces an extra level of analytical complexity when compared with the periodic buckling pattern. In the presented paper the lateral buckling pipeline is modeled by an axial compressive beam supported by lateral distributing nonlinear springs taking the soil berm effects in the horizontal plane. It is found that the model is governed by a time-independent Swift–Hohenberg equation. Based on John Burke and Edgar Knobloch’s work we conclude preliminarily that the equation will have localized solutions. Besides the qualitative conclusion, by AUTO 07P the localized solutions of the equation are studied in detail. The snakes-and-ladders structure of localized solutions explains the transition of buckling modes in theory. The range of the possible critical axial forces is found out. Meanwhile two critical axial force formulas corresponding to the range ends are presented. Finally a typical submarine pipeline is analyzed as an illustration.     

超导磁体等效材料参数的有限元预测

HT—7U超导托卡马克装置中纵场超导磁体是由多种材料组成的且具有周期性分布的大型复杂的重要结构，对其宏观等效材料参数的准确掌握在其结构设计阶段是十分重要的。本文着重介绍了利用小参数展开的渐近均匀化方法对其进行等效处理的过程，并采用有限元方法预测出其等效弹性模量与热膨胀系数等，这些都为纵场磁体结构的力学计算与传热分析提供了必要的参数。     

苜蓿草粉对金属材料磨损性能的影响

采用正交试验法在磨料磨损试验机上考察了不同粒度苜蓿草粉对45#钢和HT200灰铸铁磨损性能的影响,研究了不同载荷和转速等条件下的磨料磨损行为,采用扫描电子显微镜对其磨损表面形貌进行观察.结果表明:影响材料磨损性能的因素由大到小依次为转速、磨粒粒度和载荷;苜蓿草粉磨粒对金属材料表面的磨损为硬、软磨粒共同作用的结果;45#钢在硬磨料磨损条件下以显微切削为主要磨损机制,在软磨粒磨损条件下以多次塑性变形和低周期疲劳为主要磨损机制;HT200灰铸铁以塑性变形而产生的脆化剥落为主要磨损机制.     

Si3N4陶瓷电化学研磨特性及机理分析

采用自制的全程方向渐变型恒速平面研磨试验机考察了Si3N4陶瓷球在水基介质润滑下同灰铸铁HT250和45#钢配副时的电化学研磨特性,分析了外加电压对摩擦磨损性能的影响机理;并采用扫描电子显微镜和原子力显微镜分析了外加电压极性对Si3N4陶瓷球摩擦磨损性能的影响.结果表明,对金属盘施加正向电压导致Si3N4陶瓷球磨痕明显增大,而摩擦系数基本保持不变;施加反向电压则可使摩擦系数及Si3N4磨痕明显减小;在对比分析基础上筛选得到了兼具较高研磨效率和良好研磨表面质量的优化研磨方案,可用于Si3N4陶瓷高效研磨.     

Predominant Gas Transport in Microporous Hydrotalcite–Silica Membrane

The prepared microporous hydrotalcite (HT)–silica membrane was found to exhibit the molecular sieving characteristic of pristine silica material and high $\mathrm{CO}_{2}$ adsorption capacity of HT. The combined properties made enhanced $\mathrm{CO}_{2}$ permeability and separability from $\mathrm{CH}_{4}$ possible. The gas transport in the membrane was predominantly surface adsorption. The porous membrane overcame the Knudsen limitation and yielded the highest separation selectivity of 120 at 40 % $\mathrm{CO}_{2}$ feed concentration, $30\,^{\circ }\mathrm{C}$ operating temperature, and 100 kPa pressure difference.     

Key synthesis of magnetic Janus nanoparticles using a modified facile method

Inorganic/organic poly（methylmethacrylate-acrylic acid-divinylbenzene） iron oxide Janus magnetic nanoparticles（P（MMA-AA-DVB）/Fe3O4） with strong magnetic domains and unique surface functionalities were prepared using a solvothermal process.The P（MMA-AA-DVB） nanoparticles were prepared via soapfree emulsion polymerization and used as a precursor for preparing Janus nanoparticles.The morphology and magnetic properties of the magnetic Janus nanoparticles formed were characterized using a laser particle size analyzer,transmission electron microscopy,Fourier transform infrared spectroscopy,vibrating sample magnetometry,and thermogravimetric analysis.The synthesized P（MMA-AA-DVB）/Fe3O4 magnetic Janus nanoparticles were characterized by a Janus structure and possessed a stable asymmetric morphology after being dually functionalized.The particle size,magnetic content,and magnetic domain of the P（MMA-AA-DVB）/Fe3O4 magnetic Janus nanoparticles were 200 nm,40%,and 25 emu/g,respectively.The formation mechanism of the Janus nanoparticles was also investigated,and the results revealed that the reduction of Fe3＋ ions and growth of Fe3O4 took place on the surface of the P（MMA-AA-DVB） polymeric precursor particles.The size of the Janus particles could be controlled by narrowing the size distribution of the P（MMA-AA-DVB） precursor nanoparticles.     

Non-linear constitutive relations for magnetostrictive materials

In this paper, non-linear deformation behavior of magnetostrictive materials is studied and three magnetoelastic coupling constitutive models are developed. The standard square (SS) constitutive model is developed by means of truncating the polynomial expansion of the Gibbs free energy. The hyperbolic tangent (HT) constitutive equations, which involve a hyperbolic tangent magnetic-field dependence, are proposed to model the magnetic-field-induced strain saturation of magnetostrictive materials in the region of intense magnetic fields. A new model based on density of domain switching (DDS) is established in terms of the basic truth that magnetic domain switching underlies magnetostrictive deformation. In this model, it is assumed that the relation between density of domain switching, defined by the quantity of magnetic domains switched by per unit magnetic field and magnetic field can be described by a density function with normal distribution. The moduli in these constitutive models can be determined by a material function that is proposed to describe the dependence of the peak piezomagnetic coefficient on the compressive pre-stress for one-dimensional cases based on the experimental results published. The accuracy of the non-linear constitutive relations is evaluated by comparing the theoretical values with experimental results of a Terfenol-D rod operated under both compressive pre-stress and bias magnetic field. Results indicate that the SS constitutive equations can accurately predict the experimental results under a low or moderate magnetic field while the HT model can, to some extent, reflect the trend of saturation of magnetostrictive strain under a high magnetic field. The model based on DDS, which is more effective in simulating the experimental curves, can capture the main characteristics of the mechanism of magnetoelastic coupling deformation of a Terfenol-D rod, such as the notable dependence of magnetoelastic response on external stress and the saturation of magnetostrictive strain under intense magnetic fields. In addition, the SS constitutive relation for a general three-dimensional problem is discussed and an approach to characterize the modulus tensors is proposed.     

Ethylene–air detonation in water spray

Detonation experiments are conducted in a 52 \(\hbox {mm}\) square channel with an ethylene–air gaseous mixture with dispersed liquid water droplets. The tests were conducted with a fuel–air equivalence ratio ranging from 0.9 to 1.1 at atmospheric pressure. An ultrasonic atomizer generates a polydisperse liquid water spray with droplet diameters of 8.5–12 \(\upmu \hbox {m}\), yielding an effective density of 100–120 \(\hbox {g}/\hbox {m}^{3}\). Pressure signals from seven transducers and cellular structure are recorded for each test. The detonation structure in the two-phase mixture exhibits a gaseous-like behaviour. The pressure profile in the expansion fan is not affected by the addition of water. A small detonation velocity deficit of up to 5 % was measured. However, the investigation highlights a dramatic increase in the cell size (\(\lambda \)) associated with the increase in the liquid water mass fraction in the two-phase mixture. The detonation structure evolves from a multi-cell to a half-cell mode. The analysis of the decay of the post-shock pressure fluctuations reveals that the ratio of the hydrodynamic thickness over the cell size (\(x_{{\mathrm {HT}}}/{\lambda }\)) remains quite constant, between 5 and 7. A slight decrease of this ratio is observed as the liquid water mass fraction is increased, or the ethylene–air mixture is made leaner.     

Hybrid-Trefftz有限元法的研究进展

系统概述了Ｈｙｂｒｉｄ Ｔｒｅｆｆｔｚ有限元法及其在弹性力学中的应用．该单元模型由于在插值函数上的灵活选择性使其比普通有限元能更有效地处理局部效应问题,如孔洞,集中荷载等．通过适当选择单元插值函数可构造出高精度的ｐ－扩展元和一系列满足特殊条件的新单元,以在同等条件下提高计算精度      

时变接触特性表面对界面摩擦学行为的影响

通过在锻钢基材表面沟槽中分别填充灰铸铁HT300、Mn-Cu合金和Mn-Cu阻尼合金材料获得具有时变接触特性的表面,并对锻钢光滑表面试样和时变接触特性表面进行摩擦学试验,研究不同时变接触特性表面对界面摩擦学行为(摩擦噪声、摩擦振动以及磨损行为)的影响. 结果表明:填充HT300的时变接触特性表面缓解了界面磨损,有效延续摩擦系统的稳定状态,抑制摩擦振动和噪声的产生;相反,填充Mn-Cu合金和填充Mn-Cu阻尼合金的时变接触特性表面加剧了界面磨损,加速了摩擦系统不稳定状态的出现,进而激发出高强度的摩擦振动和噪声. 在本研究中,摩擦系统失稳引起摩擦振动和噪声主要归因于摩擦磨损过程中黏着撕裂和犁削等界面作用,填充材料的阻尼特性未能起到减振降噪的效果.      

HT-7U超导托卡马克装置极向场线圈的等效弹性常数及其残余刚度

HT－7装置的超导极向场线圈由导管，超导材料和绝缘体组合而成，具有复杂的正交各向异性的性质。本文从微观力学的观点出发，将极向场线圈整体作为一种复合材料来考虑，采用微观力学的复合律和损伤力学的细观损伤模型，求出了极向场线圈的等效弹性常数和残余刚度；并且，残余刚度的计算结果已得到了实验验证。这些材料特性已被用于有限元分析的输入数据。     

基于EEMD和SVR的多自由度结构状态趋势预测

由于工程结构的复杂性和引起结构损伤原因的不确定性,结构早期微弱和潜在的损伤难以识别和预测。为此提出了基于聚类经验模式分解(EEMD)和支持向量机回归(SVR)的结构健康状态趋势预测方法。首先对多自由度结构渐进损伤的加速度振动信号进行聚类经验模式分解(EEMD);再进行希尔伯特变换(HT)计算瞬时频率;然后用回归支持向量机对反映结构健康状态的瞬时频率进行趋势预测。详细分析了各种参数对回归和预测精度的影响,提出了这些参数的选用方法和一般原则。研究表明:该方法具有训练样本少的特点;在采用二阶多项式核函数、回归步长m=3~5、误差惩罚因子C=100、敏感因子ε=0.01时,可以准确地和高精度地预测结构状态趋势,预测精度达到0.24781%。     

A new type of functional chemical sensitizer $$\hbox {MgH}_{2}$$ for improving pressure desensitization resistance of emulsion explosives

In millisecond-delay blasting and deep water blasting projects, traditional emulsion explosives sensitized by the chemical sensitizer \(\hbox {NaNO}_{2}\) often encounter incomplete explosion or misfire problems because of the “pressure desensitization” phenomenon, which seriously affects blasting safety and construction progress. A \(\hbox {MgH}_{2}\)-sensitized emulsion explosive was invented to solve these problems. Experimental results show that \(\hbox {MgH}_{2}\) can effectively reduce the problem of pressure desensitization. In this paper, the factors which influence the pressure desensitization of two types of emulsion explosives are studied, and resistance to this phenomenon of \(\hbox {MgH}_{2}\)-sensitized emulsion explosives is discussed.