Search results

During making and breaking process, micro-cracks occurred along grain boundaries under electrical and mechanical forces.
These factors reduce the reliability of electrical contacts in practice.
When these contacts were applied to severe electromagnetic, thermal and mechanical forces, they would be eroded rapidly.
Localized steep Nb concentration gradient leads to fluctuation of physical properties which results in the deterioration of the material's reliability and increases the speed of commutation wear.
It will contain many influence factors involvong those discussed above.

Effect of Elliptical Dimples on Hydrodynamic Lubrication Jinghu Ji 1,a, Hao Wang1,2,b and Yonghong Fu1,c 1School of Mechanical Engineering, Jiangsu University, Zhenjiang, Jiangsu Province, China 2Intellectual Property Research Center of Jiangsu Province, Jiangsu University, Zhenjiang, Jiangsu Province, China ajijinghu@ujs.edu.cn (corresponding author), bwanghaozl@126.com, cfyh@ujs.edu.cn, Keywords: hydrodynamic lubrication, surface texturing, elliptical dimple, slender ratio, inclination angle Abstract.
Introduction It has been proved that surface texturing can improve tribological performance in mechanical components. [1].
Theoretical and experimental studies have indicated that the geometrical parameters of textures are the most important factors to optimize texturing benefits [2,3].
It was found that the dimple shape, orientation and size affect the hydrodynamic lubrication significantly.
Hence, the range affected by the ends effect in hydrodynamic lubrication may be a reasonable analysis by the length of a dimples column.

Brasses, bronzes and other copper alloys produced by powder metallurgy methods have the physical and mechanical properties of their cast or wrought counterparts.
To increase density and mechanical properties of the samples obtained they used sintering.
Nevertheless, it is necessary to arrange extra investigations of sintering in the air and estimate influence of sintering modes on physical and mechanical properties of samples.
The new copper based powder materials: structure and properties, J.
Fabrication of Carbon-Copper Composites Using Local Carbon Material: Microstructure, Mechanical, Electrical and Wear Properties, J.

If the extent and position of damage is diagnosed promptly and damages could been reinforced and repaired promptly, we can not only lengthen the entire life of bridge, moreover can safeguard the people's life and the property.
Any structure can be regarded as the mechanical system composed of the rigidity, the mass, and the damp.
Its merit is that the vibration factor can be regarded as the driving source, and the damage monitoring process does not affect the normal operating of structure, then it is possible to complete the monitoring and the recognition of damage conveniently.
(a) Simple supported beam with smaller rigidity (b) Simple supported beam with bigger rigidity (c) Continuous beam with hinged support (d) Continuous beam with fixed support Fig.1 The model of beam in four cases Table 1 Six degrees of damaged cases Cases 1 2 3 4 5 6 Damaged element no 13 31,32 13 31,32 13 31,32 13 31,32 13 31,32 Extent of damage no 5% 10% 15% 20% 25% In the computation, three kinds of different factors have been considered: rigidity of structure, boundary condition, structure system.
The reason of selecting the factor is that some steel bridge is quite gentle with relatively small rigidity and some concretes bridge is quite heavy with relatively big rigidity in the practice.

To obtain the amorphous alloy films with superior properties by method of electrochemical deposition, the accuracy requirement for the copper substrates for Alloy Films is extraordinarily strict.
The two above factors heighten the workpiece material removal rate.
The lapping velocity mainly affects the workpiece deformation velocity in the lapping machining to modify the machined surface for the physical and mechanical properties.
But the increasing lapping velocity has a little effect upon the surface roughness which depends on the properties of the abrasive grain and lapping pad.
The polishing pad made of polyurethane has superior properties such as strong wear resistance, high polishing efficiency and small deformation, but the requirement for the surface roughness is strict.

The engine blade vibration is one of the important factors, which seriously affects the stability of the whole machine, so the vibration characteristics and the reliability of the blade are very important.
However, the randomness of the influence factors on the blade vibration frequency is ignored.
As the material property is the crucial factor of blade frequency distribution, the elast- ic modulus and the density become more important than other factors.
The Elastic modulus, the densityand the rotor speed are the main influence factors on the blade second-order vibration frequency distribution, with the sensitivity probabil- ities 35.09%, 34.56% and 24.15% respectively
Probability Design Method of Margins of Safty for Reliability Characteristic Par- ameters of Space Mechanical Products [J].

Considering the site geotechnical investigation report and relative standards, the safety factor of side friction of uplift bored piles in soft rock was defined according to the testing of frictional resistance between concrete short pile and lightly weathered silty mudstone.
The bedrock has no faulted structures, far from the Guangzhou-Conghua Fault and Shougouling Fault and is comparatively complete with undeveloped fissure, well mechanical properties. the bedrock lack variety and occur in the alternating layer of celadon calcareous mudstone and maroon silty mudstone, which have relatively small thickness of monolayer, less than 3 meters and have no different in anti-press intensity of rock.
Local rock has strong different weathering, affected by the lithology and fractures and groundwater.
Site representative borehole diagram as shown in Fig. 1 and rock mechanical performance indexes are shown in Table 1.
Guangdong standard "Design code for building foundation" states that the bearing capacity characteristic value of single friction short pile can be defined by the way of dividing ultimate friction resistance by safety factor that is not less than 3. the problem is that the exact value of safety factor is undefined.

They have found the most important factor that affects warpage is packing pressure.
Its properties were given in Table 1.
Table 1 Properties of PP+EPDM+20%Talc material PVT Properties Mechanical Properties Solid density(g/cm3) 1.0476 Elastic modulus(MPa) 1530 Melt density(g/cm3) 0.86622 Shear modulus(MPa) 550 Recommended mold temperature(℃) 40 Poisson’s ratio 0.392 Recommended melt temperature(℃) 220 Fibers/Filler (Talc filled) 20% Table 2 Process parameters and their levels Number Uncoded Parameters Levels low high 1 Mold temperature(℃) 30 50 2 Melt temperature(℃) 200 240 3 Coolant temperature(℃) 20 40 4 Injection time(s) 1.6 2.0 5 V/P switch-over 97% 99% 6 Packing time(s) 18 22 7 Packing p (% Inject p) 60 100 6 Coolant Reynolds number 8000 12000 FFD experiments for warpage.
In any experiment involves the study of the effects of two or more factors, then factorial designs are most efficient than one-factor-at-a-time experiments.
The following conclusions can be drawn based on the experimental results. (1) The melt temperature was the most principal factor affecting the warpage in injection-mold. (2) Increasing coolant temperature and decreasing V/P switch over under higher mold temperature has a negative influence on reduction of warpage, and increasing coolant temperature and V/P switch over under lower coolant temperature has a positive influence on reduction of warpage. (3) According to the structural analysis, it is seen that the strongest point is point A and the weakest point is point D.

The material properties of the AA5754 aluminium are listed in Table 1.
Table 1: Compositions and mechanical properties of 5754 alloy 0-0.40 0-0.50 0-0.10 2.6-3.6 0-0.40 Fe Mn Cu Mg Si Nominal composition (Balance Al) 63.5 22 240 70 Hardness (Hv) Elongation (%) Tensile Strength (MPa) Young's Modulus (Gpa) MECHANICAL PROPERTIES 0-0.40 0-0.50 0-0.10 2.6-3.6 0-0.40 Fe Mn Cu Mg Si Nominal composition (Balance Al) 63.5 22 240 70 Hardness (Hv) Elongation (%) Tensile Strength (MPa) Young's Modulus (Gpa) MECHANICAL PROPERTIES Figure 1: Lap shear and T-peel samples dimensions (not in scale) Results and Discussion Figure 2 shows the lap shear, cross tension and T-peel test results for two sets of SPR samples.
Depending on failure mode, the key influential factor can generally be discovered.
Westgate, "Fatigue properties of clinched, self-piercing riveted and spot welded joints in steel and aluminium alloy sheet", TWI Report, 680/1999, (1999)
Olivier., "Comparison of static properties of point and hybrid joints in steel sheets", TWI Report, 695/2000, (2000)

The modified material surpassed the initial aluminum in wear resistance by a factor of 2.4 and in microhardness by a factor larger than 4.
Eliezer, Synthesis, properties and applications of titanium aluminides, J.
Teer, Structure and mechanical properties of co-deposited TiAl thin films, Thin Solid Films 420-421 (2002) 386-391
Chen, Tribological properties of titanium aluminides coatings produced on pure Ti by laser surface alloying, Surf.
Tolkachev, Complex Electronion Plasma Treatment of Titanium: Methods, Structure, Properties, High Temperature Material Processes 21(1) (2017) 53–64, doi: 10.1615/hightempmatproc.2017021265 [9] V.N.