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Singh T.,National Institute of Technology Hamirpur | Patnaik A.,National Institute of Technology Hamirpur | Satapathy B.K.,Indian Institute of Technology Delhi | Kumar M.,National Institute of Technology Hamirpur | Tomar B.S.,Allied Nippon Industries Ltd
Journal of Materials Engineering and Performance | Year: 2013

Friction composite formulation consisting of decreasing nanoclay/lapinus fibres content, increasing graphite/aramid fibres content, and master batch of phenolic/barite is designed, fabricated, and characterized for their mechanical, thermo-mechanical, and tribological studies in braking situations. A standard test protocol is adopted for evaluating braking performance. The nanoclay content (≤2.25 wt.%) enhances hardness, impact strength, storage, and loss modulus characteristics of the friction composites. Such composites exhibit higher friction stability as well as variability coefficient. However, composites with higher content of nanoclay (∼2.75 wt.%) exhibit moderate level of stability coefficient and minimum variability coefficient. Fade performance improves with nanoclay content whereas friction fluctuations increase continuously with increasing nanoclay content. The disc temperature continuously rises with nanoclay contents, it becomes maximum for nanoclay content 2.75 wt.%. The same composition found to be effective in arresting temperature rise, arrests fading, improves recovery, moderate stability with minimum variability coefficient, and higher level of μ-performance hence recommended. The wear performance deteriorates with lapinus/nanoclay content and improves with the amount of aramid/graphite in the friction composites. Worn surface morphology study (using SEM) reveals the associated wear mechanisms responsible for wear of investigated composites. XRD study confirms the presence and dispersion of nanoclay with other composite ingredients. © 2012 ASM International.

Satapathy B.K.,Indian Institute of Technology Delhi | Majumdar A.,Indian Institute of Technology Delhi | Jaggi H.S.,Indian Institute of Technology Delhi | Patnaik A.,National Institute of Technology Hamirpur | Tomar B.S.,Allied Nippon Industries Ltd
Computational Materials Science | Year: 2011

Targeted material design (TMD) following combinatorial engineering approach based on experimentally determined performance defining attributes (PDA) of a series of heterogeneous friction-composites is attempted via non-linear regression optimization (NLR-OPT) technique. The four key PDAs have been rigorously evaluated on a Krauss friction testing machine. The four selected performance defining attributes (PDA) are performance-friction, wear, friction-fade and friction-recovery. Based on the performance data two target-composite formulations are designed adhering to friction-maximization norms. The theoretically obtained formulation designs for a target set of PDA were later validated by fabricating actual composites followed by their performance assessment on identical testing set-ups and test-regulation. The two targeted composite formulations were also replicated for flyash derived cenospheres in addition to the raw flyash based composites. Finally, the deviations in PDA are critically analyzed from material composition point of view and the adopted approach gives rise to minimal deviation from the magnitude of theoretically estimated PDA. The study has successfully demonstrated that non-linear regression technique based optimization for targeted material design of heterogeneous composites with multiple performance goals may prove to be a sound and viable engineering approach for material designers. © 2011 Elsevier B.V. All rights reserved.

Jaggi H.S.,Indian Institute of Technology Delhi | Satapathy B.K.,Indian Institute of Technology Delhi | Patnaik A.,National Institute of Technology Hamirpur | Mehra N.C.,University of Delhi | Tomar B.S.,Allied Nippon Industries Ltd
Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology | Year: 2013

Flyash-filled glass fibre reinforced composites have been fabricated and evaluated for drag braking performance on a chase friction testing machine following SAE J 661a standard. The friction build-up and decay phenomena in the drag braking mode as a function of drum temperature have consistently been found to be in the composites with ~5-7.5 wt% of glass fibres, whereas the absolute friction effectiveness remained higher in the composites with maximum flyash/maximum glass fibre contents. Temperature-dependent friction performance remained broadly composition specific and qualitative correlations of performance to compositional attributes have been found to be complex. Topographical variations and their possible roles in controlling the tribological performance have been characterized by worn surface morphology. Scanning electron microscopy-energy dispersive X-ray combined analysis have revealed that at higher amount of glass fibre content in combination with flyash, the composite exhibited enhanced noise and judder propensity apart from higher Fe-content deposition on friction film. The energy dissipation ability modes as revealed from dynamic mechanical analysis showed not only a correspondence between the damping ability of the composites and compositional variations but also qualitatively established a correlation between wear and storage moduli. © IMechE 2012.

Tiwari A.,Indian Institute of Technology Delhi | Jaggi H.S.,Indian Institute of Technology Delhi | Kachhap R.K.,Indian Institute of Technology Delhi | Satapathy B.K.,Indian Institute of Technology Delhi | And 2 more authors.
Wear | Year: 2014

Friction composites utilising cenosphere and barium sulphate as major fillers were fabricated both separately and in combination. Thermal analysis revealed initial degradation temperature >500. °C irrespective of the composition. Mechanical properties viz. hardness, compressibility and shear strength were found to be well above the standard values as per the industrial practice. Dynamic mechanical response demonstrated improved storage and loss moduli for barium sulphate based composites. Tribological assessment conforming to the regulation-90 as per the Economic Commission for Europe (ECE) norms revealed improved wear resistance, enhanced recovery, lower disc temperature rise and reduced friction fluctuation for cenospheres based composites. Composites containing both fillers showed cenospheres dominated tribological response. Empirical correlation between wear, friction coefficients and dynamic mechanical properties as temperature controlled parameters was developed to predict wear. Worn surface analysis of the brake pads was carried out by scanning electron microscope (SEM) to visually analyse the associated wear mechanism at the braking interface through various topographical attributes viz. primary and secondary contact plateaus. © 2013 Elsevier B.V.

Satapathy B.K.,Indian Institute of Technology Delhi | Majumdar A.,Indian Institute of Technology Delhi | Tomar B.S.,Allied Nippon Industries Ltd
Materials and Design | Year: 2010

The performances of flyash based fibre reinforced-phenolic composites have been rigorously evaluated on a Krauss friction testing machine following PVW-3212 norms as per the "Economic Commission for Europe" (ECE) regulations and have been discussed in-terms of fade, recovery, performance friction coefficient, wear and disc-temperature rise. The present paper deals with tribo-performance analysis in-terms of sensitivity of the overall performance due to any fluctuations in six selected performance defining attributes (PDA) specifically with regard to friction-fade, friction-recovery, wear, disc-temperature rise and averaged friction performance. The relative weights of importance of the PDAs with respect to overall friction performance have been elicited by the Analytic Hierarchy Process (AHP). The ranking of the friction materials has been carried out by the Technique for Order Preference by Similarity to Ideal Solutions (TOPSIS). In the sensitivity analysis part, the weightage of the PDAs were systematically varied within a specified range to assess the response of different friction materials so as to optimally design materials for varied friction applications. © 2009 Elsevier Ltd. All rights reserved.

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