Amit Aherwar

An investigation on gearbox fault detection using vibration analysis techniques: A review

Abstract Gears are critical element in a variety of industrial applications such as machine tool and gearboxes. An unexpected failure of the gear may cause significant economic losses. For that reason, fault diagnosis in gears has been the subject of intensive research. Vibration analysis has been used as a predictive maintenance procedure and as a support for machinery maintenance decisions. As a general rule, machines do not breakdown or fail without some form of warning, which is indicated by an increased vibration level. By measuring and analysing the machine’s vibration, it is possible to determine both the nature and severity of the defect, and hence predict the machine’s failure. The vibration signal of a gearbox carries the signature of the fault in the gears, and early fault detection of the gearbox is possible by analysing the vibration signal using different signal processing techniques. This paper presents a review of a variety of diagnosis techniques that have had demonstrated success when applied to rotating machinery, and highlights fault detection and identification techniques based mainly on vibration analysis approaches. The paper concludes with a brief description of a new approach to diagnosis using neural networks, fuzzy sets, expert system and fault diagnosis based on hybrid artificial intelligence techniques.

Preliminary evaluations on development of new materials for hip joint femoral head

Development and selection of a proper biomaterial with diverse properties (i.e. physical, mechanical, wear, corrosion, and many others) for hip femoral head is one of the most exigent tasks. Improper material often causes component failure during functioning. Therefore, in this study, a series of implant materials containing tungsten of different weight percentages were fabricated by high temperature vacuum casting induction furnace and the physical, mechanical, wear, and corrosion properties were examined. The proportions were varied from 0 wt% to 4 wt% in a cobalt–chromium alloy (Co–30Cr–4Mo–1Ni). The mechanical properties were tested by the micro-hardness tester and the compression testing machine, while the wear performance was analyzed through a pin-on-disc tribometer under different operating conditions at room temperature. Corrosion resistance was analyzed under NaCl solution by the electrochemical test method. Due to the conflict between the properties obtained, the Vise Kriterijumska Optimizacija Kompromisno Resenjemeaning (VIKOR) method integrated with analytic hierarchy process (AHP) was applied to choose the best material among the set of alternatives, where AHP was used to determine criteria weights, and VIKOR approach was used to rank the alternatives. From the results obtained, it was found that Co–30Cr–4Mo–1Ni implant material containing 2 wt% tungsten provides the best combination of the properties for a given application (i.e. hip femoral head).

Preliminary Evaluations on Development of Recycled Porcelain Reinforced LM-26/Al-Si10Cu3Mg1 Alloy for Piston Materials

The current work deals with an endeavor to synthesis, metal composites by taking aluminum alloy (i.e. LM 26) as matrix material and porcelain (powder form) as reinforcement. The metal composites were fabricated with different weight percentages (0wt%, 2wt%, 4wt%, 6wt% and 8wt%) of recycled porcelain reinforced LM 26 aluminum alloy by using high temperature vacuum casting induction furnace and the physical, mechanical and wear properties were measured. The micro hardness, compressive strength, tensile strength and flexural strength were increased with the increase in porcelain weight percentage. From the results obtained, it was found that 6wt.% porcelain reinforced composite exhibits maximum wear resistance as compared to other compositions of composites. Furthermore, the surface morphology of the worn out surfaces and cross-sectional microstructure of the fabricated composites were analyzed by using scanning electron microscopy (SEM) to understand the wear mechanism and microstructural changes, respectively by increasing the composition of porcelain (0-8wt.%) for the base composition of Aluminum LM-26 alloy. The obtained findings indicate that LM 26 aluminum alloy containing 6wt.% porcelain can be recommended for tribological use of this composite in manufacturing automobile spare parts including piston material.

Biocompatibility evaluation and corrosion resistance of tungsten added Co-30Cr-4Mo-1Ni alloy

Biomaterials are continuously being developed to overcome the drawbacks of existing materials and provide improved function in artificial organs. Currently Co-Cr based alloys are used in many medical applications such as hip and knee implants which still require modification to better perform. In this article, therefore, the influence of tungsten allying element on electrochemical corrosion resistance and biocompatibility behaviour of a recently developed Co-30Cr-4Mo-1Ni alloy composition were investigated. The tungsten modified alloys were prepared by using a high temperature vertical vacuum casting technique at five different weight percentages (0-4wt.% tungsten). The electrochemical corrosion behaviour of all the samples under NaCl solution was studied by using potentiodynamic scan method. The corrosion characteristics were investigated in terms of corrosion potential (Ecorr) and corrosion current density (Icorr). From the results of the analysis, it was observed that out of all samples, an alloy with 2wt.% of tungsten in composition (i.e. Co-30Cr-4Mo-1Ni-2W) exhibited better corrosion resistance. Furthermore, histopathological evaluations in subcutaneous tissue were performed in rats according to the standard ISO 10993 to examine the biocompatibility of the prepared samples. The results showed no evidence of inflammatory cell migration, no epidermal necrosis, no vacuolar degeneration of basal cell, no adnexal atrophy and vesicle formation of any samples. The obtained findings indicate that Co-30Cr-4Mo-1Ni-2W can be used in biomedical applications including femoral component of hip and knee implants.

Prediction of effect of tungsten filled Co-30Cr-4Mo-1Ni metal matrix biomedical composite alloy on sliding wear peculiarity using Taguchi methodology and ANN

Abstract Artificial neural networks have appeared as a better candidate to arithmetical wear models, due to their competence of handling non linear behaviour, learning from experimental results and generalisation. In this study, an ANN technique was applied to predict the effect of tungsten filled particulates on sliding wear performance of fabricated Co-30Cr-4Mo-1Ni biomedical metal matrix alloy composite for hip implant application with distilled water medium. In order to appraise the behaviour of fabricated biomedical alloy composite fulfilling diversified performance measures, Taguchi methodology has been espoused. An orthogonal array and statistical analysis of variance were used to identify the significant factor setting for obtaining better performance output. Confirmation test were carried out to verify the experimental results. The surface morphology of the worn out surfaces and cross-sectional microstructure of the fabricated alloy composite were analysed by using SEM to understand the wear mechanism and microstructure. Finally, the responses have been predicted using both ANN and Taguchi method so that a comparative evaluation can be made. From this analysis, it can say that neural network predicts the responses more precisely than Taguchi prediction. This study will give an idea for hip implant application but not direct replacement of human joints.