The radical ring-opening polymerization (rROP) of α-lipoic acid (LA) and its derivatives represents a synthetically accessible, efficient, and scalable strategy to impart degradability into functional copolymers. This review highlights recent advances in the design of sustainable materials containing LA through rROP driven by heat and/or light.

This article presents a comprehensive study on the damping of vibrations in a motor-pump assembly using viscoelastic and constrained layer damping treatments. The assembly's structural model, designed using SolidWorks software, is subjected to modal and harmonic analyses in ANSYS. The primary goal is to mitigate vibration amplitudes originating from the motor and pump to enhance the assembly's operational performance. Three damping treatments are investigated: Free Layer Damping (FLD), Sandwich Constrained Layer Damping (CLD), and a novel Multilayer CLD approach. The viscoelastic material is modeled using the Prony series method, and its properties are incorporated into the finite element analysis Results demonstrate that the application of damping treatments significantly reduces vibration amplitudes compared to the untreated structure. Among the treatments, the Multilayer CLD approach exhibits the highest damping efficiency, reducing the maximum amplitude by approximately 52% compared to the base structure. The study showcases the advantages of utilizing viscoelastic and constrained layer damping techniques for enhancing vibration control and operational stability in industrial assemblies. The research findings contribute to the field of structural dynamics and vibration control, offering valuable insights into the design and optimization of mechanical systems subjected to dynamic loads. This study opens avenues for further research and practical applications aimed at improving the performance and reliability of motor-pump assemblies and similar industrial equipment.

Epoxy thermosets are usually limited by their inherent brittleness and low-impact resistance. Henceforth, a series of bio-based epoxy resins were synthesized from gallic acid (GA) esters. Varying the chain length of flexible poly(ethylene glycol) (PEG) enabled tailoring the thermomechanical properties of the thermosets. Decreasing the chain length of the epoxy prepolymer, resulted in the increase of tensile strength from 2.89 to 15.18 MPa with a decrease in elongation from 121.7 to 16.91% and an increase in viscosity of the epoxy resins from 5.25 to 228.46 Pa.s. The low viscosity of epoxy resins with longer chain lengths offers good processability and broadens their relevance as reactive diluents for resins of high viscosity. Additionally, the thermosets exhibited decent transparency and UV shielding ability with satisfactory biodegradable attributes. The study revealed a direct correlation between chain length and thermomechanical properties of the epoxy thermosets.

In this report, the proposed compound (Ba0.95Zn0.05)(Ti0.95Sn0.05Se0.05)O3 is synthesized by mixed oxide route for the extensive study of the dielectric and electrical properties. The crystallization, symmetry, structure (tetragonal), space group (P4mm), and lattice parameters were confirmed by an X-ray diffraction study. The dielectric and electrical properties in a wide range of temperatures and frequencies of this particular composition deduce various interesting properties on high dielectric permittivity, low tangent loss, relaxation mechanism, non-Debye type conduction, and negative temperature coefficient of resistance. From the frequency and temperature dependence, dielectric loss shows a very low loss factor (<0.06) at low temperatures (<250 °C). Nyquist plots discuss the contribution of grain and grain boundary by fitting it with the help of the software ZSimpWin. The PE loop measurement showed that the corresponding hysteresis had main parameters for (Ba0.95Zn0.05)(Ti0.95Sn0.05Se0.05)O3 compound, remnant polarization (Pr = 0.28 µC/cm2) and coercive field (Ec = 1.35 kV/cm). All the above characteristics conclude that it may be applicable in electronic device industries.

With the increasing trends of integrated circuit densification, device miniaturization, and exponential growth of microelectronic components there is a huge responsibility on the part of material researchers to derive, design, and develop new materials. Materials that can overcome the existing limitations in the present compounds available in the market or can expedite the process of material fabrication are of great interest. This feat can be achieved by the fabrication of new materials, and analysis of various characterizations viz. (structural, dielectric, transport behavior, and impedance spectroscopy). With this perspective, in this communication, a high permittivity dielectric material belonging to the Y-Ba-Cu-O ternary systems where barium is replaced by calcium (Y2CaCuO5) is synthesized using solid-state reaction route. X-ray diffraction, scanning electron micrograph, and energy-dispersive X-ray spectroscopic study confirm the phase and microstructure of the sample. The observed higher value of the dielectric constant is understood from Koop’s phenomenological theory and internal barrier layer capacitance model. The dispersive behavior of conductivity is interpreted by Jonscher’s power law. Overlapping large polaron tunneling model for conduction is observed. Impedance spectroscopy analysis reveals non-Debye type of relaxation with variable time constants. According to Nyquist plots; up to 250 °C only grain effect (bulk) is dominantly present; however, at higher temperatures, the contribution from both grain and grain boundary is seen.

The energy density and wide availability of logistic fuels such as JP8 and diesel continue to hold importance as energy carriers for strategic applications. In some fuel cell system applications, such logistic fuels must be reformed on-board to a hydrogen-rich syngas. The relatively well-studied catalytic reforming presents numerous challenges including soot formation and catalyst deactivation when used for commercial or military grade diesel. To address these challenges, we have designed and built a non-catalytic autothermal reformer for liquid hydrocarbons. In this paper, we present experimental data on the performance of this reformer and draw important insights from this data. Results indicate that reactant mixing upstream of the reformer, turbulent Reynolds number and Damkohler number along with operating parameters such as the oxygen-to-carbon ratio and the steam-to-carbon ratio play important roles that affect reactor performance. Currently, we have achieved a carbon-conversion of 88% with an overall reformer efficiency of 82%. We expect further conversion and efficiency improvements once a more efficient reacting mixer is introduced upstream of this reformer, leading to improved technology readiness levels.

Engine gear failures are of significant concern across a wide range of industries. It is important to investigate each gear failure in light of its unique loading and operating conditions for root cause analysis (RCA) and further corrective actions to avoid such failures in the future. The aim of this study was to investigate the premature failure of a flywheel gear of a marine diesel engine and establish the root cause and damage mechanisms using experimental and numerical analysis techniques. A bottom-up creative approach was adopted to assess the loading conditions on the failed gear by first estimating the bending deformation of the failed securing bolt, assuming overload torque on the flywheel caused an equivalent bending moment permanently bending the bolt. Von Mises equivalent stress acting on the gear was numerically estimated as σVM = 737 MPa, which was found significantly more than the specified yield strength of gear governing material AISI 1055 (σY = 550 MPa). SEM fractography revealed a quasi-cleavage failure mechanism in the ‘case’ region near the gear root and a ductile failure mechanism inside the ‘core’ region of the flywheel gear. A crack was found to initiate from the gear root consisting of high-stress concentration under overload stresses. RCA established that the flywheel gears had failed by overload stresses, caused due to overload torque generated from sudden inertial thrust in the internal combustion (IC) engine due to excess fuel throttle opening.

A comparative investigation on rotating bending fatigue behaviour between unnotched and notched specimens of friction stir-welded (FSW) AA6061-T651aluminium alloy joints has been conducted under completely reversed cyclic loading (R = −1). Post-weld aging treatment was done for 8 h at 200°C on the welded joints. After post-weld aging treatment, the fatigue strength was significantly improved, while the grain size remained unchanged. Microstructural evolution before and after post-weld aging treatment was studied using orientation imaging microscopy (OIM) and transmission electron microscopy (TEM). It was found that post-weld aging treatment decreased dislocation density and facilitated precipitation hardening through the reprecipitation of fine β″(Mg2Si) particles. Fine particles of post-weld aged specimens of FSW joints were sheared by dislocations generated during cyclic loading, resulting in difficult crack initiation and tortuous crack propagation. Fractographic results confirmed that Post-weld aged specimens of FSW joints have better fatigue resistance than as-welded specimens, owing to the presence of significant precipitates along the grain boundary.

Abstract An Al-7Si-0.3Mg (A356) alloy reinforced with 5 % boron carbide (B4C) particulates was produced through squeeze casting technique at a temperature of 710°C. Friction stir processing (FSP) was employed on an A356-5% B4C composite with optimized parameters, viz., tool advancing speed of 15 mm/min and tool rotation speed of 250 r/min for one pass and two passes. High-temperature flow behavior of the FSPed A356-5% B4C composite was investigated by strain rate jump (1 × 10−3 to 5 × 10−1 s−1) compression tests using a thermomechanical simulator at temperatures of 470°C and 500°C. Strain rate jump tests revealed superplastic region with strain rate sensitivity index m = 0.4 in the lower strain rate regime of 1 × 10−3 to 5 × 10−2 s−1. However, the value of m reduced to 0.3 upon two-pass FSP. The reduction in m is attributed to the more uniform redistribution of hard Si particles throughout the composite, as examined by microstructure evolution in scanning electron microscopy, linked with energy-dispersive spectroscopy and electron-backscattered diffraction facility.