In this work, we investigated the influence of bolt geometry on the bimetallic corrosion of galvanized steel bolts and low carbon steel plate (in joint/couple state) in acidic (pH 4) and alkaline (pH 9.2) electrolyte solution. The potential and current density distributions as well as metal thickness loss across square, hexagonal, and round bolts with pitch circle diameter (PCD) 70mm, 80mm, and 90mm are simulated using 3D finite element model in COMSOL multiphysics. We have also performed complimentary non-destructive experiments for estimating the metal thickness loss to validate our simulations. It is found that the round shape bolt with PCD 70mm positioned with LCS plate exhibits the lowest metal loss in both environments, thus corroborating with the catchment area principle and highlighting the importance of bolt geometry in mitigating the galvanic corrosion. Our simulations are in close agreement with experimental results (i.e., error <±10%), thereby confirming the validity of the model. Our work opens ample avenues of bridging multiphysics computation framework with experiments to alleviate galvanic corrosion problem in bolted assemblies of automobile parts further demonstrating the utility of advanced non-destructive techniques for model validation.

Additive manufacturing (AM), also known as layer-by-layer manufacturing or 3D printing, finds a unique niche in materials processing/fabrication technology to fabricate various complex structures with excellent mechanical, thermal, chemical, and physical properties. In recent years, with the advent of technology, it has become possible to fabricate stimuli responsive smart materials and structures (SRSMS) using AM, thus demonstrating their applications in micro-/nano-electromechanical systems (M/NEMS), energy harvesting, robotics, and biomedical engineering. The manufacturing of SRSMS falls under 4D printing, where change in the printed configuration of the material when subjected to external stimuli over time is evident. Although much has been reported about SRSMS including their synthesis and fabrication and structural and functional properties, much less is known about their applicability at commercial scale. In the same vein, 4D printing for SRSMS, particularly shape memory alloys (SMA) and shape memory polymers (SMPs), is expected to create a major impact on product design and manufacturing transiting from static to dynamic structures. In view of this, the present chapter provides comprehensive insights into SRSMS fabricated via AM (or 4D printing) along with the underlying stimuli responsive mechanisms and integrated functionalities. We classify AM SRSMS according to the material (i.e., polymer and alloys), fabrication process, and stimuli response. At the end, we consider the present challenges and key issues in AM SRSMS comprehensively that can be addressed in near future to accelerate the design and development process of SRSMS.

This study systematically demonstrates the ancient iron-making process in one of the earliest iron-smelting sites in India, and Naikund, Vidarbha region, dating as far back as 900 BC. During the process, the maximum temperature attained in the Naikund furnace was estimated to be ~1150–1250°C in the reaction zones where solid-state reduction of iron followed by separation of the low-melting slag phase and metallic iron were predominant. The low melting point of the slag phase is possibly due to the addition of sand or silica and limestone in the furnace during the iron-making process. Further-more, mass balance studies performed using the Rist diagram superimposed with the Fe-C-O stabi-lity diagram revealed that the minimum charcoal rate was about 1900 kg/tonnes of iron produced. It can be anticipated that the porous, semi-solid metallic iron is hammered to produce various objects used for hunting and agriculture. The thermochemical analysis of one of the earliest iron-smelting sites in India provides evidence of the ancient iron-making processes in the country. This study fur-ther opens up multitudes of possibilities to analyse ancient metallurgical structures in India.

This book focuses on fundamentals, technology, synthesis, and characterizations and applied techniques from a practical point of view of coatings. The first three chapters offer a rigorous review of the application of these coatings to corrosion protection in various aerospace and oil and gas industries, and the subsequent chapters present a quick critical review of the state-of-the-art protection techniques of these coatings to novel biomedical applications such as clinical translations and tissue-engineered materials. Environmental, ergonomics, and aesthetic aspects and future perspectives are also explained at the end. Features: • Explores the synthesis and application techniques of novel smart coatings in various research areas • Presents a concise, critical, and state-of-the-art review of existing research on various types of smart coatings • Ascertains the different mechanisms associated with the stimuli response of smart coatings • Includes an exclusive chapter on real-time applications in the biomedical field • Covers self-healing, self-cleaning, pH balance, early corrosion detection, and triggering mechanisms This book is aimed at researchers and graduate students specifically in smart coatings and thin films and corrosion, including chemical, materials science engineering, industrial and manufacturing engineering, and nanotechnology.

The indentation response of polycrystalline soft doped-lead Zirconate Titanate (PZT) with varying ferroelectric domain configurations is investigated using nano and micro indentation. The as-poled (AP) PZT samples are selectively annealed at below and above the Curie temperature, Tc, to obtain different ferroelectric domain configurations. In the fully depoled state (with completely random ferroelectric domain configurations), PZT exhibit higher hardness, H (∼ 40%) as compared to AP PZT (where ferroelectric domains are highly ordered). Severe cracking is observed at the imprint corners at high indentation loads and ferroelectric domain configurations are visualized in the vicinity and ahead of the indentation crack using piezoresponse force microscopy. The ferroelectric domains remain fully plastic in the regions from where the crack has propagated and just ahead of the crack, while farther from the indentation crack, they are elastic. The indentation fracture toughness, KICi values computed from the cracks emanated from imprint corners indicate that ferroelectric domain configurations also influence toughening behavior of PZT. The results are rationalized using remnant strain, εr and converse piezocharge coefficient, d33* measured around the indentation crack. This work highlights the new pathways to tailor strength and toughness of PZTs.

The nanomechanical properties of polycrystalline “hard” and “soft” lead zirconate titanate (PZT) (abbreviated as PZT-H and PZT-S, respectively) are measured on samples having different ferroelectric domain configurations. The ferroelectric domain configurations are varied by selectively annealing the as poled samples below and above the curie temperature, Tc. The ferroelectric domain configurations characterized using piezoresponse force microscopy reveal that the degree of randomization of ferroelectric domains increases with increasing annealing temperature. Nanoindentation experiments reveal that the above Tc annealed samples exhibit the highest hardness, H among all the samples. All the samples, exhibit strong indentation size effect where H decreases with increasing in indentation load. The possible reasons for enhancement in Hin annealed samples is attributed to the differences in ferroelectric domain configurations, defect dipoles, and oxygen vacancies. The results provide insights about designing piezoelectric materials with good combination of mechanical and piezoelectric properties.

Piezoelectric materials contain microstructural features (e.g., domain walls, interdomain spacing, and grain size) that span across several length scales, i.e., few nm in the case of interdomain wall spacing to several μm in case grain sizes. Recent experimental findings indicated that the domain configurations have more influence on the hardness of these materials than the grain size. In this study, nanoindentation experiments are conducted on polycrystalline PMN-PT (a relaxor ferroelectric material) with a focus to investigate the influence of domain configurations on the indentation size effect (ISE) in hardness, H. Different domain configurations are achieved by selectively annealing the as poled samples above and below the Curie temperature. Nanoindentation hardness is obtained in the load range of 1–5 mN with the maximum penetration depth well below the grain size of the samples. The experimental results reveal that all the samples, albeit to a different order, exhibit strong Reverse Indentation Size Effect (RISE) and normal ISE in H. The observed ISE is then analyzed using classical Meyer's law, the proportional specimen resistance (PSR) model and modified PSR (mPSR) model. The critical analysis of nanoindentation data reveals that the PSR model provides a satisfactory understanding of the genesis of RISE and ISE considering the elastic resistance of test material and frictional resistance at indenter facet/test material.

In this work, nano ZnO powders were used in the electrodeposition of zinc phosphate coatings to mitigate the detrimental effects of corrosion on low carbon steel. Our results showed that nano ZnO powder promotes the formation of hopeite (Zn3(PO4)2·4H2O) and phosphophyllite (Zn2Fe(PO4)2·4H2O) phases which are the main constituents of phosphate conversion coatings. The surface morphology, chemical composition, the growth process and anticorrosive performance of these coatings are examined using SEM, EDS, XRD and electrochemical measurements. Electrochemical characterization results suggest, nano ZnO incorporated phosphate coatings exhibit a lower corrosion rate (∼1.89 mpy) in 3.5% NaCl solution against normal zinc phosphate coatings (∼5.68 mpy) which is well supported by microstructural examination. It is believed that positive shift in corrosion potential and marked reduction in the current density helps in the formation of compact coatings with full crystalline surface coverage suggesting the corrosion protection mechanism offered by these coatings is a diffusion controlled process.

Micromechanics based models are used for the effective estimation of elastic properties of polymer matrix composites. This paper presents a novel and efficient micromechanical computational approach for effective estimation of elastic properties of polymer matrix composites. The strategy begins with the review of some notable micromechanics based models and then to bridge the gap between the limitations of these models. The analytical study based on Mori-Tanaka estimates for the effective estimation of elastic coefficients is carried out. Finite Element (FE) simulations using Representative Volume Element (RVE) are outlined in order to verify analytical results. It was found that Mori-Tanaka estimates and FE predictions are in agreement. Mori-Tanaka model predicts the values accurately for lower volume fractions due to dispersion approximations. However, the extent of elastic coefficient estimates at large volume fractions with inclusion of Eshelby's tensor in Mori-Tanaka method is still regarded as open for the future advancement of this work.

The domain configurations such as domain size, orientation, and interdomain spacing have a significant influence on the electromechanical properties of piezoelectric materials though their role on mechanical properties is not well understood. In this manuscript, we have systematically varied the domain configuration of polycrystalline lead magnesium niobate-lead titanate (PMN-PT) piezoceramics (by annealing them below and slightly above the Curie temperature, Tc) and determined the nanomechanical properties. Nanoindentation experiments performed on pristine, sub and above-Tc annealed samples in the peak load range of 1 mN–5 mN reveals a strong indentation size effect (ISE) in hardness, H. Further, it is observed that the sub-Tc annealed samples exhibit higher H and elastic modulus, E compared to the above-Tc annealed and pristine samples. In contrast to this, the piezoelectric constant, d33, decreases with increase in annealing temperature eventually approaches to “zero” for the above-Tc annealed samples, though both sub and above-Tc annealed samples have similar crystal structure. The microstructure and domain characterization indicate discernable differences in the domain structure suggesting that the differences in nano-mechanical and piezoelectric properties can be attributed to the changes in domain configurations. These results provide new insights about the novel way to engineer the domain configurations for tailoring mechanical and piezoelectric properties of the piezoceramics.

In this work, nanocrystalline phosphate coatings are systematically produced on low carbon steel with different preparation modalities using nano TiO2 and nano ZnO particles. For the sake of comparison, normal zinc phosphate coatings are also produced. All the phosphate coated samples are subjected to the thermal annealing at 100, 200, 300 and 400 °C for 1 h in argon atmosphere. Our results through combined electrochemical characterization and nanoindentation experiments revealed that nano TiO2 and nano ZnO particles act as a sealing agent, and therefore prevent crack propagation which enhances the electrochemical and mechanical properties of these coatings. Annealing treatment, along with the recrystallization of metallic matrix, promotes the corrosion resistance of all the phosphate coatings. In fact, among all the classes of coatings, annealed samples at 400 °C exhibit higher nanomechanical properties and lower corrosion rates. The results also invoked that nano TiO2 phosphate behaviour prevails over other two. Therefore, this dominant behaviour is mostly due to the accumulation of hard Zn-P precipitates upon annealing which exfoliates the outermost layer and therefore exposing the underneath layer to corrosive media, eventually delaying the onsets of corrosion attack. Our results highlight, for the first time, the ample avenues of enhancement in the electrochemical performance as well as nanomechanical properties of electrochemically deposited phosphate coatings using the incorporation of nano TiO2 and nano ZnO particles in water based phosphate bath followed by subsequent cost effective annealing treatment.

In this paper, we proposed a revised Mori–Tanaka model for the effective estimation of the elastic properties at lower fiber volume fraction. A review of some notable micromechanics-based models with the theories proposed by Voigt and Reuss, Hashin–Shtrikman model, Mori–Tanaka method and dilute dispersion scheme is carried out, and a critique is presented focusing on the limitations of these models. Finite Element (FE) simulations are performed using Representative Volume Element (RVE) technique to rationalize the analytical results. Our results revealed that revised Mori– Tanaka estimates and FE predictions are in agreement. Elastic properties of the test material are dependent on size of RVE suggesting the effective elastic modulus evaluated using RVE forms the lower bounds of true effective values. However, we still believe that there is room for the debate for evaluating the elastic properties of these composites at larger volume fractions with the inclusion of Eshelby’s tensor in Mori–Tanaka scheme. Thus the efficacy of micromechanics-based models for the effective estimation of elastic properties of polymer matrix composites is highlighted. Our findings may provide new significant insights of the effective estimation of elastic properties of PMC using micromechanics-based approach.

This current study reports on multi-level damage and creep behaviour of metal and composite material under external high pressure using finite element concept. A fatigue damage model with microcracks with improper interface has been portrayed in the present investigation. In addition, the overall elastic properties and damage evaluation are also studied and comparative study of mechanical properties has been outlined. Further thermo-elastic creep response of materials based on Norton’s law is also presented. The results showed that the proposed nonlinear constitutive model and overall elastic damage behaviour of composite material are in agreement. Implemented nonlinear constitutive model is secured by comparing predicted stress–strain curves with experimental data available in the past literature under uniaxial tension. The time-dependent behaviour creep stresses and displacements are studied and plotted. The analysis provides significant new insights of micromechanical damage, creep and collapse behaviour of composite material. For the structural composites, some notable techniques have been developed over the past three decades; review of these techniques is also outlined here in this paper and state of art is established together with insights for upcoming development.

The efficacy of nano-TiO2-containing zinc phosphate coatings on low-carbon steel is investigated. Zinc phosphate coatings are electrodeposited on low-carbon steel (AISI 1015) keeping current density, deposition time and wt % nano-TiO2 at their respective levels. Corrosion protection performance of these coatings was assessed using potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) in 3.5% NaCl electrolyte. The morphology, the composition and the growth process of the zinc phosphate coating is investigated using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, X-ray diffraction (XRD) and electrochemical measurements. The XRD study reveals that the obtained phosphate layer contains traces of hopeite and phosphophylite. The formed zinc phosphate coating offers high corrosion protection in 3.5% NaCl solution, which is well supported by EIS studies. The presence of nano-TiO2 in the phosphate bath anticipated to offer a better surface coverage and reduction in porosity and forms more homogeneous coating, which is in agreement with the SEM studies. The optimization of the electrodeposition phosphating process for achieving better responses in terms of corrosion rate and coating resistance is addressed in this paper.

The mechanical properties of composite materials undergo degradation with an increased number of loading cycles. The objective of this paper is to propose a progressive failure analysis approach using Hashin's criteria. The initiation and propagation of intralaminar failure mechanisms: Matrix tension, matrix compression, fiber tension and fiber compression are identified. The stiffness degradation at a specific integration point in the material is observed. Complimentary FE simulations are performed to investigate the progressive failure analysis of composite materials employing Hashin's criteria. The efficient use of Hashin's criteria identifies the different failure modes. An attempt is made to demonstrate the interaction mechanism between the intralaminar damage and interlaminar delamination occurring in composite laminates. The effectual use of Hashin's criteria helps to obtain different damage indices and damage variables using allowable material properties. The proposed new insights of progressive failure analysis approach ensure the high fidelity of these materials in generic aerospace and underwater structures. However, the efficacy of progressive failure analysis for the strain localization problems in composites is still regarded as open for the future advancement of this work

This current study reports on comparison of nonlinear buckling behaviour of composite material under external hydrostatic pressure using finite element concept. Triaxial failure analysis has been employed at micro level to predict the damage behaviour and failure envelopes of polymer carbon-fiber reinforced composite involving thickness stresses. In addition, a buckling pressure equation based on ASME codes customized to IM7/8552 composite material was also presented. Finite element analysis using solid 3D shell element 190 with finite strain for IM7/8552 composite material have been performed in order investigate the validity of finite element method. Pre and post failure material nonlinearity in composite material has been discussed. The scope of present study is directed towards proposing the nonlinear constituent failure criteria and inelastic buckling behaviour of composite material at hydrostatic pressure. Furthermore, theoretical studies were done in conjunction with analytical studies to verify numerical analysis. It was found that IM7/8552 has failed due to its material nonlinearity having orthotropic properties. Optimal and accurate convergence in solution was observed and finite element analysis results are validated successfully. It can be concluded that there was significant increase in the mechanical properties as a function of hydrostatic pressure ranging from 0.13 to 1.20%. Allowable buckling pressure is anticipated by thickness to diameter ratio focuses geometric nonlinearity in material. The ASME equation and Windenburg equation (ABS) reveals in good prediction of design factor (∼ 3.5) for allowable buckling pressure. The progressive damage analysis showed finite element analysis and theoretical results are in agreement. The further scope of this study involves in development in failure constituent criteria with new damage analysis incorporating pressure and low temperature effects.

Fracture toughness and fatigue crack growth resistance (FCGRs) of butt-welded joints of copper and steel were measured. For this purpose, compact tension C (T) specimens were machined out from plain (unwelded) base materials and welded joints. The different zones of the welded joints viz., Ni-weld, Cu (HAZ), Steel (HAZ), interface between Cu and Ni-weld (Int. A) and interface between Ni-weld and steel (Int. B) were subjected to testing. Mode I crack, parallel to the weld was introduced in each zone. In both tests, the welded assembly showed inferior performance against crack compared to the unwelded base materials. In fracture toughness tests, load vs. load line displacement curves were obtained. A stable ductile crack growth was observed for copper and Ni-weld. While brittle-fracture was observed for steel. Cu (HAZ) exhibited highest load and displacement. Steel (HAZ) had shown highest load but the least displacement. The interface A and Ni-weld have shown loads and displacements closer to that of Cu (HAZ). The interface B had shown the least load but displacement comparable to that of Cu (HAZ) and Ni-Weld. In elastic regime, HAZ of En31 displayed highest toughness and the Int. B, the lowest. On the other hand, in elastic-plastic regime, HAZ of Cu had shown the highest toughness and the Int. B, the lowest. The number of fatigue cycles undergone by the Ni-weld was highest and by the steel (HAZ), the lowest. Hence, the Ni-weld showed the highest resistance to the growth of the crack under fatigue. In both the tests, if the crack had deflected it was towards the low strength-material and not necessarily towards the low toughness-material. The different behaviours of the zones are attributed to their different microstructures, yield strengths, thermal expansion coefficients and elastic moduli.

The maturity of sophisticated numerical tools for predicting damage in composite materials has become a priority research area in aero-and underwater structures. This paper proposes a modeling approach to endeavor achieving high fidelity of mechanical behavior of composite materials subjected to high pressure applications. The strategy begins with numerical methods to design an alternative material for high pressure applications and to build a ladder with experimental observations when these composites are deployed for 600 bar pressure which take into account the relevant deformation, effective estimation of mechanical properties and failure mechanisms at different length scales. Coupon-shaped specimens with different hardener-epoxy ratios were manufactured to investigate the uniaxial tensile performance and the morphological studies were carried out in order to have a picture regarding the delamination and debonding behavior of the aforementioned composites. The further scope of this work involves a review of some notable micromechanic models and to establish the state-of-art together with insights for future development. Analytical models based on the mechanics of materials (MOM) approach and Mori-Tanaka (M-T) methods are shown to estimate the elastic response of composite materials. An attempt has been made to validate these finite-element predictions with experimental observations in order to secure the capability of a numerical framework. The outcome of our study also assures that these composites can be used in advanced structural applications under different conditions.