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Abstract: The present study discusses about the effect of installation torque on the surface and subsurface deformations for thin walled 7075 aluminum alloy used in Aerospace applications. A FE model was constructed to predict the effect of torque induced stresses on thin walled geometry followed with an experimentation. A detailed surface analysis was performed on 7075 aluminum in terms of superficial discontinuities, residual stresses, and grain deformations. The localized strain hardening resulting from increased dislocation density and its effect on surface microhardness was further studied using EBSD and micro indentation. The predicted surface level plastic strain of .25% was further validated with grain deformations measured using optical and scanning electron microscopy.

A typical high-pressure hose assembly consists of hose made with synthetic polymer braids and Teflon tube crimped with metallic fittings. These hose assemblies are mainly used for aircraft landing gear application considering its high-pressure sustenance and better flexibility. The proposed study investigates the effect of thermo-mechanical stress generated due to cyclic soaking and flexibility testing at thermostatic subzero (-65°F) and high temperature (+275°F) on performance of high-pressure hose assembly. This effect is further studied through hose tear-down which was envisioned to investigate the hose layer degradation and focused on changes in inner PTFE tube, which ultimately leads to product performance issues. Keywords: braids, tear down analysis, thermo-mechanical, inter-layer abrasion.

The present study discusses about the determination of the Seal drag force in the application where elastomeric seal is used with metallic interface in the presence of different fluids. An analytical model was constructed to predict the seal drag force and experimental test was performed to check the fidelity of the analytical model. A Design of Experiment (DoE) was utilized to perform experimental test considering different factors affecting the Seal drag force. Statistical tools such as Test for Equal Variances and One way Analysis of Variance (ANOVA) were used to draw inferences for population based on samples tested in the DoE test. It was observed that Glycol based fluids lead to lubricant wash off resulting into increased seal drag force. Additionally, non-lubricated seals tend to show higher seal drag force as compared to lubricated seals. Keywords: Seal Drag, DoE, ANOVA

To meet future emission levels, the automotive industry is trying to reduce tailpipe emissions through both possible pathways, i.e. emission from engines as well as and the development of novel catalytic emission control concepts. The present study will focus on the close coupled SCR on Filter commonly known as SDPF which is a main pathway to reduce NOx along with particulate mass and number for light duty passenger cars and sport utility vehicles for BS 6 RDE/OBD 2 and future legislation like BS-7. The SDPF is a challenging technology as it is critical component in exhaust after treatment system involving in NOx and PM/PN reductions hence careful optimization of this technology is necessary in terms of space velocity requirements, temperature, feed NOx emission levels, particulate mass and ash holding capacities, NH3 storage on the SDPF, and back pressure.

Tapping is an important process in assembly of aircraft structures because on an average one millions of tapped holes are made on an aircraft structure. However, sudden breakage of the tap is the most undesirable event frequently encountered during the tapping process. In particular, this can mostly occur when small diameter internal threads are made in a ‘difficult-to-cut’ material like titanium. For this reason, it has been a topic of industrial interest in the manufacturing sector for many years. The ultrasonic vibrations assisted tapping (UVAT) is a novel manufacturing technology, where ultrasonic vibrations are provided to the work piece in the axial direction. The present work is a comprehensive study involving experimental characterization. The experimentation shows that UVAT reduces the torque during tapping as compared to that of in conventional process. There is a 19.1% reduction in torque and about 20.3% reduction in cutting temperature in UVAT over that of in CT.