Papers by Keyword: Crater

Abstract: The paper presents a comparative analysis of the dynamic loading of a polymethyl methacrylate (PMMA) target by a polyethylene (PE) projectile exposed to laser radiation with similar initial energy characteristics of the projectile and the laser pulse. The similarities and differences in the mechanisms of the target's response and its destruction to high-speed mechanical and laser action are shown. A higher efficiency of laser irradiation in the destruction of PMMA was found, and the conditions for the transition of the fracture mechanism from brittle to elastic-plastic were shown.

Abstract: Application of petroleum based cutting fluids in machining operation may cause many problems such as eye burn and skin inflation etc. Vegetables oils are good alternative to overcome such issues. In this work, experiments were carried out to study the influence of coconut oil on the performance of single point cutting tool insert in turning operation. Three cutting conditions viz. dry, wet and coconut oil were considered to evaluate the tool wear. Results obtained from the experiments highlighted the advantages of coconut oil, a considerable reduction in flank wear, crater wear and auxiliary wear was observed in the turning operation.

Abstract: The authors developed Whirling Electrical Discharge Texturing (WEDT) in order to reduce friction coefficient of cylinder-shaped parts. In previous research, the authors verified fundamental characteristics of WEDT by observation of textured surface. It was found that a crater shape and texture-area ratio can be controlled by WEDT. The texture-area ratio depends on feed speed of tool electrode. In this research, crater depth, crater diameter, texture area ratio and total removal volume of craters were investigated to confirm characteristics of WEDT in detail. In addition, tungsten wire was used as a whirling shaft in order to improve stability of whirling phenomenon. Moreover, a textured surface was finished by lapping-film in order to remove protrusions around craters and reduce friction coefficient. As a result, it was verified that the texture-area ratio slightly increased with decreasing feed speed and it was confirmed that crater depth, crater diameter, and total removal volume of craters were also related to feed speed.

Abstract: Electron beam source was applied to investigate the effect of current, voltage and the number of pulse on surface morphology evolution of high speed steel. It has been revealed that the same trend of the morphology can be acquired by varying different parameters because energy is the main influencing factor. Material own defects and electron back-scattering are the primary reason for the formation of the craters as a result of the eruption of phase boundary. Through the following self- and re-melting repairing, the craters become shallow and the holes disappear. And the planar stress wave justified by the multi-loop craters is the root of the appearance of micro-cracks and cavities.

Abstract: Body Heat Flux Mode characterised by Element Birth and Death method is built to simulate the thermal effect of target GH3536 irradiated by HIPIB with different energy parameters using the FEM (Finite Element Method) software. The thermal data of the metal surface irradiated by HIPIB is obtained. The simulated result has proved that the explosive eruption of the inner surface is the dominant mechanism of the formation of dense craters with large sizes when the ion current energy input is high.

Abstract: High current pulsed electron beam (HCPEB) is a fairly new technique for improving surface properties such as corrosion and wear resistances. One of the negative effects induced by HCPEB is the potential formation of craters on the surface of the HCPEB treated materials. These changes can impair the corrosion-resistance by promoting pitting. The mechanisms of nucleation and growth are detailed and the effect of the number of pulses on crater formation is discussed.

Abstract: Low energy high current pulsed electron beam (LEHCPEB) is a fairly new technique for surface modifications, including hardening, alloying and formation of metastable phases as well as improvement in wear and corrosion properties. The present contribution gives some new insights on the microstructure modifications encountered at the top surface of HCPEB treated metals. In particular, the potential of the technique for structure modifications associated with the use of the pulsed electron beam under “heating” and “melting” conditions are highlighted.

Abstract: High current pulsed electron beam (HCPEB) is a fairly new technique for surface modifications, including hardening, alloying and formation of metastable phases. The present contribution gives some new insights on the microstructure modifications encountered at the top surface of HCPEB treated metals. In particular, the potential of the technique for structure modifications associated with the use of the pulsed electron beam under “heating” and “melting” conditions are highlighted.

Abstract: In order to predict the geometry character of laser surface micro-texturing, the finite element analyzing software ANSYS is used to simulate temperature field and crater on the laser ablation. The influence and change regulation of laser intensity, laser pulse number and pulse duration in laser surface texturing are analyzed in detail. The simulation results conclude the best laser intensity in laser-pulse and materials interactions on certain conditions, and the best pulse duration in nanosecond laser micromachining. This research establishes the foundation for laser machining regular non-smooth surface in a rapid and effective way.