Mechanical Engineering

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The influence of circular cut-outs and geometric imperfection on the free vibration analysis of functionally graded material (FGM) sandwich plates with (2-1-2) plate configuration conditions has been investigated in this paper. Geometric imperfections, such as sine-type and global-type imperfections, are especially susceptible to plate vibration analysis, and these imperfections can be considered while studying plate vibration behavior. The governing equations are formulated based on the Lagrangian principle for the vibration analysis of the FGM sandwich plates subjected to the simply-supported and clamped boundary conditions. The results have been obtained using a C0-continuity isoparametric formulation with four noded elements having seven degrees of freedom per node. The accuracy of the present results has been confirmed by comparing the present results with the reported literature. © 2022

World University root node

(SoE) School of Engineering

Materials Today: Proceedings

Influence of geometric imperfections on the free vibrational response of the functionally graded material sandwich plates with circular cut-outs

Structural integrity of oil and gas pipelines depends on fracture toughness and metallurgical properties of pipeline steel welded joints. Dynamic fracture toughness (JId) is an important parameter to measure structural integrity in terms of fracture toughness of pipeline steel welded joints under impact loading. Welding input parameters such as current (A), voltage (V), and travel speed (cm/m) significantly affect the mechanical and metallurgical properties of the weldments; therefore, to study the cumulative effect of these parameters, author(s) used different heat input (kJ/cm) as an input parameter in the present work. In the present work, three different levels of heat input such as low heat input (LHI)15 kJ/cm, medium heat input (MHI)20 kJ/cm, and high heat input (HHI) 25 kJ/cm were employed for the fabrication of X80 pipeline steel welded joints. Thereafter, mechanical and metallurgical behavior of different locations (Fusion line (FL), FL + 1 mm, FL + 2 mm, and FL + 3 mm) in multi-pass X80 pipeline steel weld joint was investigated under cold climatic conditions (− 20 °C). The dynamic fracture toughness was measured from instrumented Charpy impact test results using three different estimation methods. Furthermore, a finite element model was developed to simulate the Charpy impact test and validate the experimental results, using the Johnson–Cook constitutive model. © 2022, International Institute of Welding.

Welding in the World

Experimental characterization of dynamic fracture toughness behavior of X80 pipeline steel welded joints for different heat inputs

This paper presents the influence of randomness in material properties on the vibration response of functionally graded (FG) nanoplates using the nonlocal continuum model. Material properties such as Elastic modulus, Poisson’s ratio, and volume fraction index are modeled as independent random variables. A trigonometric shear-strain shape function-based refined shear deformation theory in conjunction with non-local theory has been presented for the first time to investigate the stochastic vibrational response of FG nanoplate. An efficient stochastic finite element formulation has been documented to capture the first- and second-order statistics of natural frequency. The first-order perturbation technique has been used to accommodate the effect of various material uncertainties parameters. The effective material properties have been computed using the recently developed modified rule of mixture to incorporate the porosity inclusion. The influence of conventional and unconventional (partial support) boundary constraints, porosity inclusion, small-scale effects, and material uncertainties on the vibration response of FG plates has been investigated in detail. In addition to this, the sensitivity of the functionally graded nanoplate has been observed in response to initial geometrical imperfection. It is observed that the variations in elastic modulus have a significant influence on the stochastic characteristics compared to Poisson’s ratio. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.

Archive of Applied Mechanics

Size-dependent stochastic vibration response of compositionally graded nanoplates with system randomness using nonlocal continuum model with partial support

Biomimetic and soft robotics research has been inspired by many biological organisms focusing on soft structural composites reinforced by stiff constituents. In the case of synthetic soft structural materials, hydrogels are very similar to the biological soft tissues/organs, owing to their “wet and soft” properties, their elastic performance, biodegradability, and biocompatibility. However, the current scope of hydrogel applications is usually hampered by their feeble mechanical properties. Although significant progress has been made in developing intense, challenging, and stretchable hydrogels, it is still challenging to realize the optimal magnitude of physical and mechanical properties altogether in synthetic hydrogels. This review briefly focuses on the hydrogel fibrous shape-morphing composite structure and its functionalities. The nature-inspired, fiber-reinforced soft hydrogel shape-morphing functional composite structure delivers them a cartilage-like anisotropic behavior. They could have broad potential applications in various areas, including tissue engineering, soft robotics, stretchable and bio-integrated electronics, microfluidics, and biomedical devices. Copyright © 2022 Goyal and Mitra.

Fulltext

Frontiers in Materials

A Brief Overview of Bioinspired Robust Hydrogel Based Shape Morphing Functional Structure for Biomedical Soft Robotics

An opaque photovoltaic combined with thermoelectric cooler (PV-TEC) collector is presented in this chapter, in which a TEC module is incorporated at the base of a PV module to improve the overall electrical efficiency of the system. A mathematical model has been described with photovoltaic combined thermoelectric cooler with a duct of air and this thermal modeling is used to calculate the thermal and electrical energy gain. On an annual basis, weather data is received from IMD Pune for the month of May. Several types of temperatures such as solar cells, thermoelectric cooler top side, thermoelectric cooler bottom side, duct outlet temperatures have been calculated through the thermal modeling developed for the system. These results show overall electrical efficiency with TEC increasing by 10.34-12.01%. The addition of a thermoelectric module with a photovoltaic module increases the electrical power from 6.93176 W-15.6753 W to 7.64854 W-17.5571 W. The thermal energy gain by the photovoltaic-thermoelectric module along the duct is in the range of 7.89134 W-20.7169 W. © 2023 Nova Science Publishers, Inc.

Energy Conversion: Methods, Technology and Future Directions

Performance analysis of solar energy conversion technology

Lecture Notes in Mechanical Engineering

Performance Analysis of PCM-Integrated Greenhouse Dryer

Multistable laminates have attracted the attention of researchers for developing morphing structures, as they can stay in different stable configurations without any need for external forces to maintain any of those configurations. In this study, a novel application of a reconfigurable antenna made with rectangular composite laminates [90/0] in the shape of a star is analyzed using the Variational Asymptotic Method (VAM), which is free of ad-hoc assumptions and highly accurate, unlike semi-analytical theories present in the literature. The star shaped laminate is modeled as a plate using geometrically exact kinematics, and thermal analysis is done by applying uniform temperature to obtain its cool-down shape, which shows multistability. Snap-through forces are applied on the structure to change to the other stable configurations. Three parametric studies are performed to identify the variation of snap-through force. These studies are carried out by varying the aspect ratio, curing temperature, and thickness of the individual rectangular laminates to identify the lower and upper limits beyond which the laminate loses its multistability. All studies performed using VAM are validated against 3D FEA in ABAQUS are found to be in good agreement with each other although, VAM handled the 3D problem at the 2D level achieved by systematic dimensional reduction. The computational efficiency is found to increase by almost 70% compared to 3D FEA. © 2022 Taylor & Francis Group, LLC.

Mechanics Based Design of Structures and Machines

Snap-through analysis of multistable laminate using the variational asymptotic method

The present study focuses on investigating the bifurcation characteristics of a pitch–plunge aeroelastic system possessing coupled non-smooth nonlinearities, both in structural and aerodynamic fronts. To this end, a freeplay nonlinearity is considered in the stiffness of the pitch degree-of-freedom. The effects of dynamic stall arising due to large instantaneous angles-of-attackare incorporated using the semi-empirical Leishman–Beddoes aerodynamic model. A systematic response analysis is carried out to discern the bifurcation characteristics of the aeroelastic system considering the airspeed as the system parameter. At low airspeeds, a series of dynamical transitions, including aperiodic responses, occur predominantly due to the structural freeplay nonlinearity while the flow remains attached to the surface of the wing. However, beyond a critical value of airspeed, the system response is dominated by high amplitude pitch-dominated limit-cycle oscillations, which can be attributed to stall flutter. It is demonstrated that the freeplay gap plays a key role in combining the effects of structural and aerodynamic nonlinearities. At higher values of the freeplay gap, interesting discontinuity-induced bifurcation scenarios, such as grazing and boundary equilibrium bifurcations arise due to coupled nonlinear interactions, which can significantly impact the safety of the aeroelastic system. © 2022, The Author(s), under exclusive licence to Springer Nature B.V.

Nonlinear Dynamics

Numerical investigation into discontinuity-induced bifurcations in an aeroelastic system with coupled non-smooth nonlinearities

Castor oil (CO) and cocoa butter (CB) were studied as potential hydrophobic and plasticizer additives for pectin biopolymer films. The optimum concentration of CO and CB additives and drying temperature were determined by using a 23 (two-level, three-factor) statistical factorial design of experiments. The CO and CB integrated pectin films displayed remarkably lower moisture and oxygen transmission rates relative to the control pectin films. Furthermore, the hydrophobicity, ductility (elongation at break) and flexibility (low elastic modulus) of the CO and CB added films are significantly higher than that of the control pectin films. The modified films retained 90% of their weight at a temperature of 200 °C, indicating their excellent thermal stability. A very low glass transition temperature of 2 ± 2 °C and a melting point of ~ 150 °C of the films designates their stability under processing and storage conditions. Scanning electron microscopy analysis confirmed the formation of homogeneous films without any micro-cracks or agglomerations. Detailed statistical analysis shows that the optimal conditions for producing improved pectin films: the concentration of CO (15% w/w of pectin) and CB (10% w/w of pectin) and film drying temperature (T = 35–52 °C). A coating of film forming solution comprising optimum amounts of pectin, CO and CB was able to delay the ripening of a banana by 4 days and of capsicum by 15 days at atmospheric conditions. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.

Physics

(SoNS) School of Natural Sciences

Journal of Polymers and the Environment

Castor Oil and Cocoa Butter to Improve the Moisture Barrier and Tensile Properties of Pectin Films

In this paper, we propose an idea of asymmetric bending in a fiber reinforced soft pneumatic actuator. The mixing of two intrinsically different elastomers Ecoflex 00-20 (Smooth-On, Macungie, PA, USA) and Dragon Skin 00-20 (Smooth-On, Macungie, PA, USA) with viscosities 3,000 cps and 20,000 cps respectively in various proportions and curing them all together has resulted in expected results. This can be extremely useful for how we look and manufacture soft actuators. This is going to help in cutting our costs significantly and improving the pneumatic loading strength on a greater scale. All of this, with an increased amount of precision and controllability. Experiments were carried out to determine the effects of various proportions of two different elastomers and we have also renewed the curing procedure. Our methodology can be used to design a soft actuator that bends asymmetrically without external restrictions. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.