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1.
稻谷仓壁材料摩擦系数的实验研究 总被引：1，自引：0，他引：1
利用土工合成材料综合测定仪测定了不同法向压应力（25 kPa、50 kPa、100kPa、150 kPa、200 kPa）下稻谷（水分含量为13.55%、15.14%、17.00%、19.19%w.b）与不同仓壁材料（不锈钢板、混凝土板、木板）的摩擦系数。结果表明：稻谷与不锈钢板摩擦系数较小,与混凝土板和木板的摩擦系数较大;随着法向压应力的增大,稻谷与各仓壁材料的摩擦系数均呈不同幅度的减小;随着水分的增大,稻谷与各仓壁材料的摩擦系数增大。根据实验结果,可拟合出摩擦系数与法向压应力、水分含量的关系方程。 相似文献
2.
It is studied in this paper that the influences of various factors,such as the smelting temperature,the basicity of the slag,and the quantity of reductant on the titanium content of alloy,silicon content of alloy,TiO2 content of the remaining slag and the titanium recovery in smelting silico-itanium ferroalloy using silicoaluminium ferroalloy as reductant.With this study,the optimum techn ological parameters are obtained of raising the titanium content of alloy and re-$$$ucing the silicon content of alloy. The stable experiments in laboratory and factory using this opti-mum technological parameters are conducted. 相似文献
3.
it is necessary to balance the failure risk and the maintenance expensive. A methodology for reliability based maintenance optimization of steel bridge welded joints subjected to fatigue is proposed considering linear elastic fracture mechanics (LEFM), the structure reliability, life cycle cost method and maintenance strategies. The maintenance cost is divided into inspection, repair and failure sections according to the whole life cycle cost methodology. And the maintenance strategy is transformed to the minimum expected lifetime costs with a constraint of the minimum acceptable reliability index. An case concerning to a transverse stiffener of bottom flange welded joint of Qingcaobei bridge is studied with a certain number of simplifications. Some sensitivity analysis is provided. Among all the parameters, discount rate is the most remarkable. 相似文献
4.
The stainless steel has excellent properties, but it is difficult-to-grind material. Because belt grinding shows many advantages, grinding experiments with four kinds of abrasive grain on stainless steel are carried out. The correlation mechanism between the abrasive grits and the workpiece, and influence factors on material removal rate are discussed. A scanning electric microscope was used to investigate the surface micro-shape characteristics of abrasive grit and workface. The material removal mechanism and the wearing types of abrasive belt are also analyzed. 相似文献
5.
The proliferation of weld and major alloying elements are studied and analyzed by scanning the EDS element of 316L/20G clad pipe weld joint, 316L substrate and 20G steel, and by scanning the electron microscopy and the energy spectrum analysis of 316L-weld zone and 20G steel-weld zone. The results show that the alloying elements in the weld transition layer are diluted by carbon steel, and the carbon atoms spread to the 316L and weld, while alloying elements in the 316L and wire, such as Cr, Ni, penetrate to the carbon steel, but the transition layer plays a good role in isolation, resulting in 316L stainless steel alloy element content is not significantly reduced, maintaining the 316L base metal resistant to corrosion. 相似文献
6.
采用聚氨酯发泡喷涂技术对钢板仓外表面进行保温隔热处理,之后再喷涂白色乳胶漆作为聚氨酯硬泡体的保护反光层,这种保温技术有效地控制了外温变化对钢板仓的仓温、粮温的影响,延缓仓内粮食品质劣变,保温隔热效果显著,有利于钢板仓储粮保管和储粮安全,促进低温储粮发展。 相似文献
7.
First smelting MnSi alloy by using high-bearing manganese slag of BF by electric smelting process in a 25 kVA arc furnace in lab has been introduced. In order to increase the content of manganese and silicon in MnSi alloy , a little amount of MgO is added into the slag and the lower alkalinity has been adapted. Then smelting AlMnSi alloy using MnSi alloy containing high silicon that obtained by experiments and waste Al with an induction furnace has been studied. The controlling of temperature is the key in smelting process. The high quality AlMnSi alloy has been obtained successfully,Which can be extensively used for the compound oxygen removal agent for making steel and the metal alloy additive. 相似文献
8.
KANG Ren-mu~ 《保鲜与加工》2004,(6):65-68
Cu is used as the mesosphere material in the experiment, and the diffusion-bonding experiment of Be/Cu/HR-1 stainless steel is made on the Greeble1500 hot stimulation test-machine. The interface characteristics of the diffusion bonding are studied by means of the Scanning Electron-Microscope, the X-ray Diffraction and the HV-1000 Micro-hardness Tester. The results show that Cu can countercheck the mutual diffusion between Be and Fe, as well as the diffusion of Ni and Cr from the stainless steel to Be, resultingly, restrain the formation of the intermetallic compounds among them, but the Be_(2)Cu is formed because of diffusion of Cu, and the intermetallic compounds is firstly formed along grain boundry and distributed as net-like, and the diffusion of elements is made along the grain boundry and their diffusion is non-uniform, and also does not form the layer of the single intermetallic compound. The fracture of the sample lies at the Be/Cu interface area. 相似文献
9.
In order to analyze the seismic behavior of widened beam flange joints, 16 specimens were derived from finite element models base on experiments. The effects of some parameters, such as the increased width and length, on ultimate load and ductility performance of joints were further discussed with ANSYS finite element method. According to specimen failure phenomenon of both experiment and finite element method, the weak link of the joints was found and the cracking possibility was evaluated. A theoretical analysis of the fracture mechanism of widened beam flange connection was conducted. In addition, design method of widened beam flange parameters was introduced, which will offer valuable information and reference for seismic design in steel frame joints. 相似文献
10.
By using servo control shear loading system, specimens with non-coplanar rock-like intermittent joints were tested by the way of forward and reverse direct shear, rupture mechanism and shearing law for rock bridge with non-coplanar intermittent joints were studied under direct shear. The experimental studies showed that five apparent stages are presented in the process of rock bridge rupture under direct shear, which are linear elastic stage, initiation and extension of crack, fracture and transfixion of rock bridge, climbing and occlusion of shear plane and residual friction. Rock bridge presented profile fracture plane under forward direct shear. While under reverse direct shear, band form fracture plane is showed which penetrated along with the direction of forward shear, and the shear strength of initiation and peak shear strength under reverse direct shear are bigger than that under forward shear. Crack angle, normal stress and lap proportion among adjacent joint are the main factors that influence the initiation strength and peak shear strength. The FLAC 3D simulation for the process of non-coplanar intermittent joints rock bridge rupture and formation of shear rupture surface under forward and reverse direct shear was conducted. The results of numerical simulation agreed well with those of experiment. The simulation results revealed tension crack failure of non-coplanar intermittent joints rock bridge and shear yielding mechanism of fracture plane. 相似文献
11.
Based on the real size and constrain of the wet clutch, the friction pair of temperature, stress fields coupling model, and the heat convection coefficient model are established. The transient thermal-structural coupling and the thermoelastic instability of the phenomenon of friction discs generated in overload tests are numerically simulated and analyzed with ANSYS/LS-DYNA. Additionally, the distribution of the hot spots in the circle direction and surface of the friction discs are revealed, the distribution of the stress and strain caused by the thermoelastic instability is analyzed and tested. The results show that hot spots and contact pressure are mutual promotion. The thermal expansion and stress concentration caused by temperature gradient lead to steel disc warp. The heat fading caused by the thermoelastic instability leads to steel disc failure. 相似文献
12.
Maintaining crop residue on the soil surface is an important part of conservation tillage. Although broad effects of residues on soil temperature (Ts ) are well documented, the methods to predict soil temperatures under various surface residues and tillage conditions are limited. Using the Ts at 0-, 0.05-, 0.10-, and 0.30-m depths, we developed a simplified model to predict Ts for a uniform soil from air temperature (Ta ) data. Data were collected under various tillage and surface residue conditions after wheat ( Triticum aestivum L.) harvest. Residue management treatments were disk, sweep, and no-tillage (with standing or shredded residues). The model predicts maximum and minimum Ts at 0-, 0.05-, 0.10-, and 0.30-m depths using maximum and minimum Ts measured at 2-m above the soil surface, residue mass, apparent thermal diffusivity, and initial Ts profiles. Mean absolute deviation between simulated and measured maximum and minimum surface Ts were 0.53 and 0.44 °C or less, respectively. Root zone maximum and minimum T, were simulated within 0.14 to 0.91 and 0.27 to 0.95 °C, respectively, of the measured Ts . Greater precision of maximum and minimum soil temperature predictions with depth was obtained by using apparent thermal diffusivity calculated from initial Ts profiles. The proposed model can be useful in predicting Ts profiles required for crop growth modeling. 相似文献
13.
The behavior of plate in compression plays a basic role in relevant research. There are significant differences between stainless steel and carbon steel plates in structural behavior. Analysis on the behavior of stainless steel plate in compression was presented. The development of FE models for analyzing stainless steel plates in compression was described based on the results of Rasmussen's test. And the strength curve was achieved by such advanced FE models with a high degree of accuracy. The explicit strength equations and design method were proposed for determining the local buckling strength of stainless plate and cold formed rectangular hollow section in compression. It is shown that the numerical simulation results achieved by using Quach model are accurate. 相似文献
14.
Mechanical Alloying(MA),as one of the high techniques on preparing alloy power,made it possible to alloy some materials which can not be realized with the traditional melting craft in the past.Meanwhile,the quasi-stable state and non-equilibrium state which are far from thermodynamic equilibrium and the synthesis of new materials can be realized.The technique of MA caused extensive concern in the material science field.With MA technique,the research in recent years on theory models and solid-state reactions were summarized.The applying progress of the MA technique in preparing materials such as dispersion strengthened alloy,intermetallics,function material and metastable materials(including non-crystal,pseudo crystal,supersaturated solid solution and nano-crystal) are detailed,and the development trend of the MA technique is prospected. 相似文献
15.
Zheng Zijiu Huang Weigang 《保鲜与加工》1991,(2):90-95
The effects of restraint stress on phase transformation and fracture toughness COD in weld HAZ of 15MnMoVNRE steel were studied by means of weld thermal simulation and COD testing. The results show that restraint stress accelerates phase transformation and makes the fracture toughness COD higher. 相似文献
16.
The datum line and mainly three profile height parameters of surface roughness are briefly introduced and the operation principle and system structure of AFM. IPC - 208B with high-resolution, which was successfully developed by Chongqing University, are described in detail, and the emphasis is laid on its application on the nanometer scale surface roughness. Taking stainless steel for example, its micro-structure was observed, and the surface data were analyzed and transacted by special evaluator and the values of three profile height parameters were obtained. Finally the experimental results are briefly analyzed. 相似文献
17.
以重庆主城区为研究对象,利用Landsat 8传感器OLI和TIRS获取的遥感影像为数据源,进行城市聚落特征包括地形特征、土地利用等与地表温度的差异性分析。结果表明：城市的热环境空间分布差异较大,海拔高度对温度的影响强于地形起伏度;（NDVI、NDBI、MNDWI等）和地表温度的相关关系呈分段线性关系;不同土地利用类型的热强度和热变异程度差异明显,建设用地的温度最高且斑块温度间的变异性最强,虽然水体的平均温度最低,但斑块温度间的变异性却较高;从格网分析的结果可以看出,格网内部水体的“冷岛效应”明显、建设用地的“热岛效应”显著,耕地与自然植被面积的增加使得各空间格网温度更趋向于稳定。 相似文献
18.
The ex plosio n process a n d paramete rs in the blast of large iron a nd steel wastesare analysed by using the theory of fracture mechanice.A three-dimensional model is established us-ing pressurised cylinder with multiple semi-elliptical surface cracks.Reasons are given for the expla-nation that the dynamic fracture toughness for iron and steel is generally lower than the correspond-ing static value during the blast.The importance is emphasized of the critical duration time of the dy-namic stress intensity factor for crack extension. 相似文献
19.
《Soil Technology》1991,4(2):167-175
Effects of puddling, flood-water depth and percolation rate on the thermal properties of a tropical rice soil were studied under field and glass-house conditions. Puddling increased volumetric heat capacity (CV), but decreased thermal conductivity (Kt), thermal diffusivity (Dt) and damping depth (D) compared to a nonpuddled soil. A percolation rate of 40 mm d−1 showed higher Kt, Dt and D than zero percolation. The values of Kt, Dt and D were highest with 50 mm and lowest with 10 mm flood- water depth. The Cv did not change with different flood-water depths or percolation rates. Consequently, puddling, 40 mm d−1 percolation and 50–100 mm submergence kept the maximum temperature of surface 100–150 mm soil at relatively low level under tropical conditions. These treatments also buffered soil against extreme diurnal temperature fluctuations. The time lag between maximum solar radiation and maximum temperature of submerged soil varied, on an average, between 1.2 hours at soil surface and 11.6 hours at 300 mm soil depth; which is more than that in an upland soil. 相似文献
20.
The characteristics of work piece's surface under precision abrasive belt grinding are analyzed.A comprehensive understanding of the reason of low roughness value's surface is found out,which the edge of grain formed compact and crossed micro grinding marks that can compensate for the inconsistence of grinding mark's height in single grinding direction.The grinding test of gear shaft is done for the sake of doing research on the main factors of surface roughness in grinding quenching stainless steel.The results indicate that decreasing the vertical pressure is beneficial to(reduce) surface roughness of work piece,and the surface roughness also can reach the requirement of precision processing when steadily grinding. 相似文献