Recent studies have shown that a suitably thermomechanically processed Al–Zn–Mg–Cu–Zr–Sc alloy having an essentially unrecrystallized grain structure may be subjected to superplastic deformation at a ...temperature and strain rate combination of 475
°C, 1.9
×
10
−2
s
−1 to obtain a total elongation of 650%. The present work demonstrates that the utilization of two-step strain rate at 425
°C during superplastic deformation of a similarly thermomechanically processed alloy increases the total elongation value to as high as 916%. The beneficial effect of two-step strain rate could further be realized at 350
°C to obtain a total elongation of 438%. Using electron backscattered diffraction, the present work provides a systematic assessment of the changes in (i) percentage recrystallization and (ii) recrystallized grain size with percentage elongation in the material superplastically deformed using both one- and two-step strain rates.
The influence of microstructure and texture developed by different modes of hot cross-rolling on in-plane anisotropy (
A
IP
) of yield strength, work hardening behavior, and anisotropy of Knoop ...hardness (KHN) yield locus has been investigated. The
A
IP
and work hardening behavior are evaluated by tensile testing at 0 deg, 45 deg, and 90 deg to the rolling direction, while yield loci have been generated by directional KHN measurements. It has been observed that specimens especially in the peak-aged temper, in spite of having a strong, rotated Brass texture, show low
A
IP
. The results are discussed on the basis of Schmid factor analyses in conjunction with microstructural features, namely grain morphology and precipitation effects. For the specimen having a single-component texture, the yield strength variation as a function of orientation can be rationalized by the Schmid factor analysis of a perfectly textured material behaving as a quasi-single crystal. The work hardening behavior is significantly affected by the presence of solute in the matrix and the state of precipitation rather than texture, while yield loci derived from KHN measurements reiterate the low anisotropy of the materials. Theoretic yield loci calculated from the texture data using the visco-plastic self-consistent model and Hill’s anisotropic equation are compared with that obtained experimentally.
► We prepared Al-based composites reinforced with nanocrystalline Al–Ca intermetallics. ► Two distinct approaches have been used for the dispersion of the reinforcing particles: manual blending and ...ball milling. ► It highlight the effect of inter-particle spacing on the mechanical property of the composites.
Al-based metal matrix composites reinforced 20 and 40vol.% of Al–Ca intermetallic particles have been produced by powder metallurgy. Two distinct approaches have been used for the dispersion of the reinforcing particles within the Al matrix: manual blending and ball milling. Manual blending leads to the agglomeration of the Al–Ca particles to form a cell network throughout the consolidated sample. On the other hand, the composites prepared by milling display a more homogeneous distribution of the reinforcing particles. This has a strong impact on the mechanical properties. The strength increases from 112MPa for pure Al to 140 and 165MPa for the blended composites with 20 and 40vol.%, while the strength increases to 250 and 280 for the corresponding composites produced by milling. This behavior is linked to the reduced matrix ligament size characterizing the milled composites.
In industry 4.0, shop floor management teams are increasingly focused on developing an unprecedented strategy to avoid financial losses and address the challenges and problems encountered in ...operations management. In the present scenario, the management teams use various process optimization approaches for operational control, including lean manufacturing, smart manufacturing, the internet of things, and artificial intelligence. The process optimization approach is used to maximize productivity within limited constraints on the shop floor. The present research aims to develop a smart production management system and suggest an efficient process optimization approach to enhancing industrial sustainability by identifying problems and challenges encountered in the complex shop-floor conditions in industry 4.0. The developed production management system has been prepared by classifying the challenges and problems found in the previous research work and organizing brainstorming sessions. The developed management system has been validated by a comprehensive investigation of a case study of an earthmoving machinery manufacturing unit. The analysis showed that the developed system could enhance operation excellence and industrial sustainability in industry 4.0 by optimizing the utilization of resources on the shop floor within limited constraints. The authors of the present article strongly believe that the developed production management system will improve operational excellence and would be beneficial for industry personnel and researchers in controlling operations management in shop floor management of heavy machinery manufacturing, including industry 4.0.
This work describes a correlation among texture, in-plane anisotropy in tensile properties, and yield locus in Ni-based Hastelloy C-276 alloy. The alloy exhibits moderate values of in-plane ...anisotropy and anisotropy index, which has been attributed to the presence of moderate overall intensity of texture. The alloy displays two slopes in true plastic stress–strain curve and follows a Ludwigson relation. At low plastic strains, the sample displays the presence of annealing twins and less strain localization at grain boundaries, while the formation of deformation twins and high strain localization within the deformation twins and at the grain boundaries are observed in a high-strained region. The 45-deg and 67.5-deg orientation samples show relatively low ductility and low work-hardening exponent. This has been explained based on dislocation storage capacity and dynamic recovery coefficient using Kock–Mecking–Estrin analysis.
Helical springs are mostly subjected to compression and expansion in their life cycles under working conditions in vibratory feeder. The continuous reversal stress leads to permanent deformations in ...pitch of coils of the helical springs due to creep phenomenon in which reversal stresses under various ambient conditions act as catalyst. The reduced pitch in coils of helical springs over period of time change the dynamic behavior of the vibratory feeder unit. The reduction in pitch in springs also leads to performance loss of the vibratory feeder. Therefore, it is essential to understand the dynamic characteristics of the feeder unit in order avoid catastrophic failures and performance losses. The objective of this research is to study the variations in dynamic behavior of vibratory feeder with old (reduced pitch) springs through modal analyses using FEM and EMA methods. The modal analysis using FEM technique is conducted in ANSYS workbench 14 using a three-dimensional model, which was developed in SolidWorks software. A working model of vibratory feeder was fabricated similar to the FE model for the experimental modal analysis (EMA). The instruments used in the EMA method are: one 4-channel FFT analyzer, one dynamic shaker, three accelerometers and a force transducer.
Failure of crusher components has considerable influence on the productivity of a crushing plant. In order to improve performance and operational reliability, its critical components are needed to be ...identified to make replacement in time before any catastrophic failure happens. Though traditional maintenance practices exist in crushing plants, a methodical analysis of failure trend is imperative to improve operational reliability of this critical equipment. The present paper deals with failure analysis of rock crusher and its critical components using total time on test (TTT)-plot and other statistical tools. TTT-plot has proven to be a useful tool in reliability analysis.
Microwave processing has been emerging as an innovative sintering method for many traditional ceramics, advanced ceramics, specialty ceramics and ceramic composites as well as polymer and polymer ...composites. Development of functionally gradient materials, joining, melting, fibre drawing, reaction synthesis of ceramics, synthesis of ceramic powder, phosphor materials, whiskers, microtubes and nanotubes, sintering of zinc oxide varistors, glazing of coating surface and coating development have been performed using microwave heating. In addition, microwave energy is being explored for the sintering of metal powders also. Ceramic and metal nanopowders have been sintered in microwave. Furthermore, initiatives have been taken to process the amorphous materials (e.g. glass) by microwave heating. Besides this, an attempt has been made to study the heating behaviour of materials in the electric and magnetic fields at microwave frequencies. The research is now focused on the use of microwave processing for industrial applications.
Aims
The emergence of multidrug resistant strains of Mycobacterium tuberculosis has made tuberculosis more difficult to manage clinically. With the aim of obtaining new and effective ...anti‐mycobacterial agent(s), this study investigated the anti‐mycobacterial activity of several imidazole and piperidine derivatives.
Methods and Results
Towards obtaining new anti‐mycobacterial agents, Mycobacterium smegmatis cells were treated with different compounds for their growth inhibitory activity. Among these, benzyl 1H‐imidazole‐1‐carbodithioate and allyl piperidine‐1‐carbodiothioate exhibited better inhibition than the others. Thereafter, anti‐biofilm property of these two was examined by treating M. smegmatis with these agents before and after the formation of biofilm. The result showed that both the compounds at their sublethal dose inhibited the formation of biofilm as well as dispersed preformed biofilm. Consistently, they augmented the activity of isoniazid or rifampicin against biofilm‐encapsulated cells. MTT assay was performed to examine the toxic effects of this combinatorial therapy on different cell lines. Results exhibited a low cytotoxicity for this combinatorial treatment. The activity of these two was also verified against dormant mycobacterial cells and was found to be effective.
Conclusion
The present study identified two compounds that exhibited anti‐mycobacterial activities against both planktonic and dormant cells. These two also exhibited anti‐biofilm activity at their sublethal dose and augmented the activity of isoniazid and rifampicin against biofilm encapsulated cells.
Significance and Impact of the Study
The current study provides two new agents that have the potential to be used in anti‐mycobacterial therapy and may help in public health management.
The influence of small addition of Sc on the superplastic potential of Al–Zn–Mg–Cu–Zr alloy AA 7010 has been examined. The alloy was subjected to a three-step thermo-mechanical process (TMP) and the ...resultant material (having essentially an unrecrystallized grain structure) was subjected to a strain rate–temperature combination of 1.9
×
10
−2
s
−1, 475
°C to develop recrystallized grain structure amenable to superplastic deformation. This resulted in a total elongation of 650%.
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