The interaction between friction and vibration is a widely recognised source of inefciency in all mechanical systems. The nature of this interaction is very dependent on the dynamic environment and its control requires a detailed understanding of the mathematical structure governing the stability of this environment. Although the fundamental causes of friction-induced intermittent motion have b...

The lensing properties of the Plummer model with a central point mass and external shear are derived, including the image multiplicities, critical curves and caustics. This provides a simple model for a flattened galaxy with a central supermassive black hole. For the Plummer model with black hole, the maximum number of images is 4, provided the black hole mass is less than an upper bound which ...

Steel plates with open holes are commonly used in structural assemblies. The fatigue properties of such details are influenced by bolted clamp-up and hole fabrication methods. The fracture surface, stiffness degradation and fatigue life of test specimens are investigated in detail and compared with the contemporary test data. The analysis results show that the presence of draglines greatly infl...

Conventional drilling of rock, in most mining applications, uses the mechanical impact of a metal tool to create the advancing hole. This technique, which has gradually increased in power and thus penetration rate has, however, certain inherent disadvantages. These range from the overall weight of the equipment which must be located at the free face of the hole to the maintenance of alignment o...

In order to reduce the delamination damage of carbon fiber–reinforced polymer (CFRP) drilling and improve quality, a variable feed method based on sinusoidal curve is proposed. That means, when at distance 1 mm from hole exit, rate drill would be reduced according rule curve. The compared with traditional by experiment, influence thrust force, factor, surface roughness wall exit morphology are ...

Tube hydroforming (THF) process is used to produce the complex components from the initial cylindrical tubes. In this paper, T- shape component was formed using a tube hydroforming machine and the residual stresses of hydroformed tube was determined by hole drilling method. Subsequently, the thickness distribution and residual stresses of final tube were investigated using experimental and fini...

Microdischarges in flexible copper-polyimide structures with hole diameters of 200 mm have been used as stencil masks to pattern bare silicon in CF4/Ar chemistry. The discharges were operated at 20 Torr using the substrate as the cathode, achieving etch rates greater than 7 mm/min. Optical emission spectroscopy provides evidence of excited fluorine atoms. The etch profiles show a peculiar shape...

Although laser drilling of carbon fibre-reinforced polymer (CFRP) composites offers the advantages zero tool-wear and avoidance fibre delamination compared with mechanical drilling, it consumes considerably more energy during process. This research shows that by using a new, stepped parameter parallel ring hole method, an saving 78.10% 18.37 gCO2 reduction for each hole, while improving product...

Drilling a deep vertical well at low cost is very important for accelerating the exploration and development of oil gas resources. Vertical drilling BHA design key to drill well, however still an art not science in some formation. In this paper, new mechanical model bent-housing motor established, build rate prediction method considering formation properties presented uncertainties proposed. Th...