Authors: Gong Shun Guan, Bao Jun Pang, Run Qiang Chi, Yao Zhu
Abstract: In order to simulate and study the hypervelocity impact of space debris on dual-wall structure
of spacecrafts, firstly a non-powder two-stage light gas gun was used to launch AL-sphere projectiles.
Damage modes in rear wall of dual-wall structure were obtained, and while the law of damage in rear
wall depends on projectile diameter and impact velocity were proposed. Finally, numerical
simulation method was used to study the law of damage in rear wall. By experiment and numerical
simulation of hypervelocity impact on the dual-wall structure by Al-spheres, and it is found that
AUTODYN-2D SPH is an effective method of predicting damage in rear wall from hypervelocity
impact. By numerical simulation of projectile diameter, projectile velocity and the space between
bumper and back wall effect on damage in rear wall by hypervelocity impact, and fitting curves with
simulation results, the law of damage in rear wall and dominant factors effect damage in rear wall by
hypervelocity impact were proposed.
197
Authors: Cheng Yong Wang, M.D. Chen, P.X. Yang, Jing Ming Fan
Abstract: Abrasive Suspension Jets (ASJ) is a new micro processing technique developed for
micro processing of hard and brittle materials based on the traditional Abrasive Water Jet (AWJ).
Based on drilling experiments of glass using MASJ technology, the dependence of material
removal, the depth and the diameter of the machined holes on the process parameters, such as
working pressure, processing time, standoff distance, incidence angle and concentration of
abrasives were investigated. Experimental results show that the material removal is approximately
proportional to working pressure, processing time and concentration of abrasives, except the
standoff distance. It is founded that the processing time is the most remarkable influence factor on
the material removal and the depth of the holes. But the working pressure doesn’t show obvious
effects to the material removal and the depth of hole with lower pressure in MASJ. The increase
of standoff distance will decrease the material removal and depth of hole, and the concentration of
abrasives can improve a few of drilling ability. Further, it is founded that longer processing time
and smaller standoff distance will achieve higher MASJ drilling efficiency and better quality of
hole, with 90 degree jet incidence angle.
381
Authors: Shahrin Hisham Amirnordin, Salwani Ismail, Ronny Yii Shi Chin, Norani Mansor, Mas Fawzi, Amir Khalid
Abstract: An essential component of the injector nozzle geometry is to see the results spray atomization and mixture formation of the fuel-air combustion to improve performance, and reduce pollution from a burner. Studies involving the injectors in the combustion burner are still in a small proportion, particularly in the premix injector type. Thus, this study involves the efforts to determine the appropriate diameter of the premix injector where the injector spray characteristics is produced by using Computational Fluid Dynamics (CFD). Multiphase of the volume of fluid (VOF) cavitations flow in the nozzle is determined through steady simulation while Eulerian-Eulerian two-fluid approach is used for performing mixing of Jatropha oil and air. Further simulation is conducted using a spray with a discrete phase injection at the outflow hole injector nozzle. The investigation involves the modification of nozzle geometry on three different sizes of 0.8 mm, 1.0 mm and 1.5 mm with the analysis focused on nozzle flow characteristics of the injector. The results indicate that a small changes in injector gives high impact to the spray and combustion of a burner. This shows the importance of nozzle dimensions which influences the nozzle flow and affects the spray characteristics, hence influence the combustion and emission of the burner system.
570
Authors: Tsung Chia Chen, Ming Long Xu
Abstract: Based on materials, different punch radii (0.3, 0.35, 0.4, 0.45, and 0.5 mm), two sets of diameter-diameter ratio 1.(.167, 1.25, 1.33, 1.4167, and 1.5) and 2.(1.6, 1.45, 1.33, 1.231, and 1.143), and two sets of depth ratio 1.(1.3, 1.4, 1.5, 1.6, and 1.7) and 2.(2.14, 1.875, 1.67, 1.5, and 1.36) are used for the stamping processes to analyze the simulation and experimental difference in copper sheet-metal (C1100) miniature layered cups. Prandtl-Reuss flow rule is integrated with finite deformation theory and Updated Lagrangian Formulation (ULF) to establish the incremental elastic-plastic deformation Finite Element Method in Coulomb’s Friction Law for simulating the miniature layered cup process. Generalized rmin algorithm is utilized in the forming process for dealing with elastic-plastic behaviors and die contact. From the simulation data, the relationship among deformation history, punch load, and punch stroke, the stress-strain distribution, and the distribution of the thinnest thickness by different punch radii are acquired.
69
