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Enhancing fiber surfaces through in situ growth of nanomaterials is known to improve fiber composite properties by enhancing the interface between the fiber and matrix. In this study, hydrothermal processes are used to achieve two types of interfacial modification for carbon fiber: zinc oxide nanowires (ZnO NWs) and nickel‐based metal–organic frameworks (MOF). The interfacial strengths are evaluated using single fiber push‐in tests via nanoindentation and the interfaces are analyzed through dynamic modulus‐mapping. It is found that ZnO modification increases the interface strength by 9.40%, while MOF modification yields an even higher improvement of 16.34%. The load‐displacement plots exhibit distinctive inflection points, elucidated through microstructural observations. Examining the modulus map of the interface region, a transition in the storage modulus from the fiber to the matrix is identified. A capillary flow‐based model is developed to explain the resin penetration through nanoscale features. The findings reported here indicate that the timescale for resin absorption is significantly shorter than the curing timescales for the surface modifications explored in this study. [ABSTRACT FROM AUTHOR]

The interface characteristics of the matrix and fibers significantly influence the evolution of residual stress in composite materials. In this study, we provide a methodology for reducing the residual stress in laminated composites by modifying the thermomechanical properties at the fiber–matrix interface. A hydrothermal chemical growth method was used to grow Zinc Oxide nanowires on the carbon fibers. We then utilized a novel digital image correlation approach to evaluate strains and residual stresses, in situ, throughout the autoclave curing of composites. We find that interface modification results in the reduction of residual stress and an increase in laminate strength and stiffness. Upon growing ZnO NWs on the carbon fibers, the maximum in situ in-plane strain components were reduced by approximately 55% and 31%, respectively, while the corresponding maximum residual stresses were decreased by 50.8% and 49.33% for the cross-play laminate [0°/90°] layup in the x and y directions, respectively. For the [45°/-45°] angle ply layup in the x -direction, the strain was decreased by 27.3%, and the maximum residual stress was reduced by 41.5%, whereas in the y -direction, the strain was decreased by 166.3%, and the maximum residual stress was reduced by 17.8%. Furthermore, mechanical testing revealed that the tensile strength for the [45°/-45°] and [0°/90°] laminates increased by 130% and 20%, respectively, with the interface modification. [ABSTRACT FROM AUTHOR]

In the context of a sustainable long-term human presence on the Moon, solutions for habitat radiation and thermal protection with regolith are investigated. Regolith compression is studied to choose the optimal density-thickness combination in terms of radiation shielding and thermal insulation. The applied strategy is to protect the whole habitat from the hazards of galactic cosmic rays and design a dedicated shelter area for protection during solar particle events, which eventually may be a lava tube. Simulations using NASA's OLTARIS tool show that the effective dose equivalent decreases significantly when a multilayer structure mainly constituted of regolith and other available materials is used instead of pure regolith. The computerised anatomical female model is considered here because future missions will be mixed crews, and, generally, more sex-specific data are required in the field of radiation protection and human spaceflight. This study shows that if reasonably achievable radioprotection conditions are met, mixed crews can stay safely on the lunar surface. Compressed regolith demonstrates a significant efficiency in thermal insulation, requiring little energy management to keep a comfortable temperature inside the habitat. For a more complete picture of the outpost, the radiation protection of lunar rovers and extravehicular mobility units is considered. [ABSTRACT FROM AUTHOR]

Our research investigated the energy absorption characteristics of chiral auxetic lattices filled cylindrical composite tubes subjected to a uniaxial and lateral quasi-static load. The lattice structures were manufactured using a 3D printing technique. Carbon fiber composite tubes without filler material were initially subjected to uniaxial and lateral quasi-static crushing load. The same types of experiment were then performed on chiral lattices and chiral lattices filled composite tubes. For the different cases, the load–displacements curves were analyzed and the specific energy absorption (SEA) values were compared. The SEA capability for the axial quasi-static crushing of the chiral lattices filled composite tubes decreased in comparison with the hollow composite design. However, the most significant result was that the average SEA value in the case of lateral loading increased dramatically in comparison with the hollow composite configuration. [ABSTRACT FROM AUTHOR]

The present study aims to measure the solid–liquid interface temperature of an evaporating droplet on a heated surface using a thermoresponsive polymer. Poly(N-isopropylacrylamide) (pNIPAM) was used owing to its sensitive optical and mechanical properties to the temperature. We also measured the refractive index variation of the pNIPAM solution by using the surface plasmon resonance imaging (SPRi). In particular, the present study proposed a new method to measure the solid–liquid interface temperature using the correlation among reflectance, refractive index, and temperature. It was found that the reflectance of a pNIPAM solution decreased after the droplet deposition. The solid–liquid interface temperature, estimated from the reflectance, showed a lower value at the center of the droplet, and it gradually increased along the radial direction. The lowest temperature at the contact line region is present because of the maximum evaporative cooling. Moreover, the solid–liquid interface temperature deviation increased with the surface temperature, which means solid–liquid interface temperature should be considered at high temperature to predict the evaporation flux of the droplet accurately. [ABSTRACT FROM AUTHOR]

Featured Application: Mechanical structural parts such as automobile parts made of aluminum alloy that have long-term stable compressive residual stress and require an extremely hard surface. The peening solution treatment was performed on AC4CH aluminum alloy by ultra-high-temperature and high-pressure cavitation (UTPC) processing, and the peening natural aging was examined. Furthermore, peening artificial aging treatment by low-temperature and low-pressure cavitation (LTPC) was performed, and the time course of peening natural aging and peening artificial aging were compared and investigated. It was found that when the AC4CH alloy is processed for an appropriate time by UTPC processing, compressive residual stress is applied and natural aging occurs. In addition, the UTPC processing conditions for peening natural aging treatment with high compressive residual stress and surface hardness were clarified. After peening artificial aging by LTPC processing, the compressive residual stress decreases slightly over time, but the compression residual stress becomes constant by peening natural aging through UTPC treatment. In contrast, it was found that neither natural nor artificial peening natural aging occurs after processing for a short time. [ABSTRACT FROM AUTHOR]

Featured Application: Cancer-targeting T1 magnetic resonance imaging contrast agent. Ultrasmall nanoparticles are potential candidates for application as high-performance imaging agents. Herein, we present the synthesis and characterization of folic acid (FA)-conjugated polyacrylic acid (PAA)-coated MnO nanoparticles with an average particle diameter of 2.7 nm. FA conferred cancer-targeting ability, while PAA conferred good colloidal stability and low cellular cytotoxicity on the FA-PAA-coated MnO nanoparticles. Further, the nanoparticles exhibited a high relaxivity (r1) value of 9.3 s−1mM−1 (r2/r1 = 2.2). Their application potential as cancer-targeting T1 magnetic resonance imaging contrast agents was confirmed by their enhanced T1 contrast enhancements at the brain cancer (U87MG) site upon intravenous administration to mice tails. [ABSTRACT FROM AUTHOR]

Fused Deposition Modelling (FDM) enables the fabrication of entire non-assembly mechanisms within a single process step, making previously required assembly steps dispensable. Besides the advantages of FDM, the manufacturing of these mechanisms implies some shortcomings such as comparatively large joint clearances and geometric deviations depending on machine-specific process parameters. The current state-of-the-art concerning statistical tolerance analysis lacks in providing suitable methods for the consideration of these shortcomings, especially for 3D-printed mechanisms. Therefore, this contribution presents a novel methodology for ensuring the functionality of fully functional non-assembly mechanisms in motion by means of a statistical tolerance analysis considering geometric deviations and joint clearance. The process parameters and hence the geometric deviations are considered in terms of empirical predictive models using machine learning (ML) algorithms, which are implemented in the tolerance analysis for an early estimation of tolerances and resulting joint clearances. Missing information concerning the motion behaviour of the clearance affected joints are derived by a multi-body-simulation (MBS). The exemplarily application of the methodology to a planar 8-bar mechanism shows its applicability and benefits. The presented methodology allows evaluation of the design and the chosen process parameters of 3D-printed non-assembly mechanisms through a process-oriented tolerance analysis to fully exploit the potential of Additive Manufacturing (AM) in this field along with its ambition: 'Print first time right'. [ABSTRACT FROM AUTHOR]

Featured Application: The current work is a step towards developing a virtual laboratory for engineering materials for targeted applications using a microstructurally informed crystal plasticity-based numerical simulation model. Physics-based and phenomenological crystal plasticity numerical simulations provide an opportunity to develop microstructurally informed models for multi-phase material. The Düsseldorf Advanced Material Simulation Kit (DAMASK) has been developed as a flexible tool for modeling and studying the several deformation mechanisms of such materials at the microscopic and macroscopic scales. In the recent past, several methodologies and techniques were developed for obtaining or constructing microstructural details and calibrating the physics-based model parameters for single-phase and multi-phase materials. Combining and standardizing the devised methods with an appropriate database can help establish a virtual laboratory to analyze the effect of microstructural attributes on the mechanical behavior of multi-phase materials. This article deals with the comprehensive background of the developed techniques and methods for the multi-phase materials class by the current research group. The combinations of different experimental and numerical techniques to validate results are explained along with the advantages and limitations. The ideas of combining the different available tools and the associated challenges are discussed. The article presents some recent work related to the phase parameters identification of the multi-phase materials and detailed insight into the obtained results. [ABSTRACT FROM AUTHOR]

The reasons for the high electrical conductivity of bismuth ferrite due to its natural composite structure, structural non-stoichiometry, redox processes, and the boundary position in the perovskite family have been considered. It has been shown that it is possible to significantly (2–3 orders of magnitude) reduce the conductivity of BiFeO3 by introducing large-sized ions of rare-earth elements (REE: La, Pr, Nd, Sm, Eu, Gd with 0.94 ≤ R ¯ ≤ 1.04 Å) in amounts of up to 10 mol %. An interpretation of the observed effects has been given. A consideration about the appropriateness of taking into account the presented results when developing devices using materials of the BiFeO3/REE type has been expressed. [ABSTRACT FROM AUTHOR]

A low friction coefficient and high bearing capacity can improve the service life of implants in the human body. In this study, we firstly investigate the mechanical properties of inorganic thermal oxide coatings on titanium alloy (Ti6Al4V). Tribological experiments were performed for different tribo-pairs under uniform conditions. The inorganic thermal oxide coating on Ti6Al4V formed at 300℃ was found to have excellent tribological properties and can effectively improve the bearing capacity of Ti6Al4V. The organic poly (vinylphosphonic acid) (PVPA) on Ti6Al4V has excellent anti-friction properties, which can help achieve superlubricity. An inorganic thermal oxide/organic PVPA composite coating was fabricated on Ti6Al4V to obtain a surface with low friction and high bearing capacity. It is found that the presence of the thermal oxide doubled the bearing capacity of the composite coating compared to that of the PVPA coating alone. This study can serve as a guide for the modification of artificial joints. [ABSTRACT FROM AUTHOR]

In this study, a relatively low temperature synthesis technique; graphitic structure by design (GSD), was employed to grow multi‐walled carbon nanotubes (MWCNTs) over carbon fiber fabrics. The MWCNTs forests were grown into two different morphologies, uniform and patterned. Hybrid carbon fiber‐reinforced polymer composites (CFRPs) were fabricated based on the hybrid reinforcement. Double cantilever beam tests were performed to investigate the effect of the surface grown nano‐reinforcements on the Mode I interlaminar fracture toughness (GIc) of the hybrid CFRPs. Results revealed that the surface grown MWCNTs enhanced the GIc of the CFRPs by 22 and 32%, via uniform and checkerboard‐patterned growth morphologies, respectively. Fractography was also employed to reveal the MWCNTs' role in interlaminar crack stoppage and deflection resulting in improving GIc of the hybrid CFRPs. POLYM. COMPOS., 40:E1470–E1478, 2019. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]