Review on thermal, thermo-mechanical and thermal stress distribution during friction stir welding

Abstract: Thermal has significant effects on the metal structure during welding process; it plays vital roles in rearranging molecular structure of the metal being welded. It is of great importance to have the knowledge of thermal, temperature, thermo-mechanical and heat distribution on the workpiece in friction stir welding as this will help in designing process and the model parameters for welding application in the following welded joints, edge butt, lap, square butt, T lap, fillet, multiple lap etc. The physics of heat generation must be explored in order to understand the workability of friction stir welding (FSW). The FSW process begun with initial friction of mechanical that took place between the tool and the welded surface resulting in the generation of heat. Since the discovery of Friction Stir Welding (FSW) in 1991, many researchers have done tremendous investigations into the process and many experimental, theoretical, numerical, empirical, computational and analytical methods have been carried out in order to analyse and optimize FSW and to understand the complex mechanism in friction stir welding at the same time to deal with effects of various parameters relating to thermal profile during the process of FSW

Composition, characteristics and socioeconomic benefits of palm kernel shell exploitation - an overview

Abstract: Intensive research has increased the creation of new biomaterials with specific engineered properties. It is on record that a large amount of these biomaterials waste are generated by the processing of palm oil that invariably causes an environmental problem. This review study sheds light on various applications that palm kernel shell (PKS) has been used for in the recent years and applications that could also be considered in the near future. It has been reported that tropical belt of Africa, Asia and Brazil are the highest producers and exporters of palm oil across the globe and by implication the most producers of the PKS. The PKS as a biomaterial waste product got after the processing of palm oil has been extensively utilized in the various form of applications for both technical and environmental benefits varying from additive, energy production, reinforcement, aggregation, water purification and as well as a composite matrix. It was observed that great use of this waste product is prominent in the structural components, automotive parts as well as water detoxifier. The PKS-powder has been characterized in this review through the use of Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) analysis. The milling was done with the aid of digital Vibratory disc milling machine for 0, 10, 15 and 20 min. Zero min was taken to be when it was sieved with a 300 μm ASTM standard sieve. It was established in the study that the duration of the milling affects volume, surface area, particle size, pore size distributions, micro structure and some other mechanical properties as well as the morphology of the powder. The particles size got reduced from 300 μm to average diameter of 200 nm. The variations in elemental compositions of palm kernel shell powder from as they were affected by milling. The micrographs revealed that there was a tremendous reduction in grain size from 300 μm to about 200 nm

Shape memory polymer review for flexible artificial intelligence materials of biomedical

The self-healing and biocompatibility of polymer composites for biomedicine have made them a preferred approach for small-scale tissue engineering elements. By moving from static to dynamic pressure, 4D printing simulates the natural physical-mechanical changes of living tissue over time. A promising new platform with excellent controllability actuation is required to enhance the significance of 4D printing for biological applications. This study systematically analyses current 4D printing technologies for the flexible fabrication of artificial intelligence (AIM) materials. In addition, many potential applications of flexible 4D printing in composite biological engineering are thoroughly investigated. We found that knowledge about this new category of flexible AIM composites is relatively limited, and the potential for practical applications has not yet been demonstrated. Finally, we discuss the problems and limitations of flexible 4D printing technology, AIM, and future approaches and applications.</p

Entropy Generation of Graphene Nanoplatelets in Micro and Mini Channels: Nanofluid Flow in Automotive Cooling Applications

The present study examines the entropy generation of graphene nanoplatelet (GnP) suspended in different basefluids, theoretically. GnP in water (W), ethylene glycol (EG) and ethylene glycol- water (EGW, 1:1) was examined under laminar flow state in a unit length mini and micro-channel of 3mm and 0.05mm diameter. The coefficient of conductivity (Ck) and viscosity (Cμ) of the nanofluid were determined from experimental analysis and their order of magnitude were established for analysis of entropy generation in mini and micro-channels. Entropy generation by fluid friction (Sgen, ff) in the channels containing EG was higher than with W and EGW by 75.6% and 79.9%, respectively. Thermal irreversibility (Sgen, th) of W was lower by132.9% and 58.2% compared to EG and EGW. Sgen,th in all the fluids decreased with increased solid volume fraction in minichannels, while, Sgen,ff increased with increase in volume fraction for micro-channels. Total entropy generation (Sgen, tot) of water was lower by 75.6% and higher by 64.8% compared to EG and EGW, respectively in a micro-channel, whereas Sgen, tot of water was lower by 123.7% and 38.4% compared to EG and EGW, respectively. As GnP volume fraction was increased in the basefluids, entropy generation ratio decreased, highlighting the positive influence of thermal properties of the nanofluid. A lower Bejan number for water (Bew), 36.8% and 358.9% were observed compared to EG and EGW in microchannel, whereas Bew was lower by 3.8% and 13.8% when compared to EG and EGW nanofluids in the mini channel

Experimental analysis of nanostructured PEEK, African giant snail shell, and sea snail shell powder for hydroxyapatite formation for bone implant applications

This experimental research focuses on the nanostructure analysis of three materials; polyether ether ketone (PEEK), African land giant snail shell (ALGSS), and sea snail shell (SSS) powder, for the formation of hydroxyapatite (HA) coatings in bone implant applications. The study aimed to evaluate these materials’ surface characteristics, furrow depth, density, and other relevant parameters to assess their suitability as bone implant materials. The nanostructure analysis revealed distinct characteristics for each material. PEEK exhibited shallow furrows and a high density of furrows, making it a favourable substrate for hydroxyapatite coating formation. The ISO 25178 roughness analysis further characterised surface roughness and topography. African land giant snail shell powder, displayed a high material ratio, indicating a potential for hydroxyapatite conversion for biomedical application. The sea snail shell powder demonstrated intermediate furrow depth and density, warranting further investigation for optimisation as a precursor for hydroxyapatite coatings. The findings emphasise the significance of nanostructure properties in bone implant materials. The tailored nanostructure of materials such as PEEK, the synthesized powder can influence their biocompatibility, osseointegration, and long-term performance. The novelty of this research lies in the comprehensive analysis of the nanostructure properties of these materials, contributing to the understanding of their potential for bone implant applications. Overall, this experimental research is significant and provides valuable insights into the nanostructure characteristics of PEEK, African land giant snail shell powder, and sea snail shell powder and they all demonstrated the potential of forming hydroxyapatite coatings.</p

Wear characteristics, reduction techniques and its application in automotive parts – A review

Wear phenomenon impact the operating efficiency and service life of engineering materials due to the influence of surface interaction at different working conditions. Successive tribological studies on wear-resistant materials in the last decade is estimated at approximately 40 of friction and wear, including laboratory tests. Most locally improvised wear testers in accordance with American Society for Testing and Materials (ASTM) and European (EN) standards, though, achieves 95-97 parametric accuracies with reduced cost, they hardly harmonize degradation and Archard’s coefficients for all possible wear factors, providing little data for simulation of mechanical and chemical wears which are responsible for non-uniform aggregation of wear patterns in practice. Complexities of intermeshing factors which combine to influence the effectiveness of developed test devices span over loads, speeds, temperature, pressures and ambience for various applications. This study highlights the techniques of wear characterization, test standards and wear reduction with emphasis on surface texturing for improved eta/beta phase re-arrangements at low working temperatures in the enhancement of grain contraction during high bias-voltage cathodic substrate multi-phase coating, phosphating during pretreatments using peening techniques, residual stress reduction during cryogenic heat treatments as well as the impact of suitable architectural matrix composite strengthening, microstructures and material reinforcements as suitable factors to influence improved tribological behaviors in materials. Optimal additive manufacturing (AM‐fabricating) techniques with pretreatments, thermal cycling and tempering can engineer enhanced anti-tribocorrrosion in Automotive components