In the present research work, the effect of abrasive water jet (AWJ) machining parameters such as jet operating pressure, feed rate, standoff distance (SOD), and concentration of abrasive on kerf width produced on graphite filled glass fiber reinforced epoxy composite is investigated. Experiments were conducted based on Taguchi's L 27 orthogonal arrays and the process parameters were optimized to obtain small kerf. The main as well as interaction effects of the process parameters were analyzed using the analysis of variance (ANOVA) and regression models were developed to predict kerf width. The results show that the operating pressure, the SOD, and the feed rate are found to be significantly affecting the top kerf width and their contribution to kerf width is 24.72%, 12.38%, and 52.16%, respectively. Further, morphological study is made using scanning electron microscope (SEM) on the samples that were machined at optimized process parameters. It was observed that AWJ machined surfaces were free from delamination at optimized process parameters.

Abrasive particles in the suspension mixture in an abrasive water suspension jet (AWSJ) machining causes acute skin friction effect thereby effectively changing the jet diameter due to wear, which in turn influences jet exit kinetic energy. This results in lowering the life of the jet for effective machining. In consideration of this aspect, the present work examines the effect of inlet pressure on skin friction coefficient and jet exit kinetic energy. It is inferred from the analysis that an increase in inlet pressure causes a significant increase in skin friction coefficient and also results in proportional increase in the exit kinetic energy of the jet. Further, it is revealed from the analysis that an increase volume fraction of abrasive (abrasive concentration) in water results in significant decrease in the skin friction coefficient and jet exit kinetic energy.

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The structural design and development of Solid rocket motor (SRM) is currently based on method of casting solid propellant grain into a metallic or composite casing. In general, SRM is subjected to diverse loading conditions during transportation, storage and firing, due to which cracks may be developed in solid propellants because of excessive loads. Finite element analyses (FEA) based on displacement method, were conducted in order to determine the integrity and the ultimate service life of solid rocket motors. The displacement based finite elements have the limitation of evaluating the distribution of stress and strain on the solid propellants which are viscoelastic in nature. In this paper, a finite element study based on Herrmann formulation is discussed to overcome this limitation in which 8node quadrilateral,9-node quadrilateral and 6-node triangular axisymmetric finite elements have been developed and analyzed for stress and strain distribution for head and mid segments of solid propellant rocket motor subjected to thermal loading. Results obtained from present study are compared to that obtained using MARC, commercial FEA software. and three degrees of freedom of nearly incompressible propellant element [18]. Present study does not require tying of the nodes. Whether the structure is made of compressible or nearly incompressible materials, the present study does not require tying option for the nodes at the interface. It can be concluded from the above-considered numerical problems that the present axisymmetric element can be used for examining the structural behaviour of rocket motors having nearly incompressible and incompressible materials.