Hasil untuk "Materials of engineering and construction. Mechanics of materials"

Christopher A. Mizzi, Osman El-Atwani, Tannor T. J. Munroe et al.

The "high-entropy" paradigm has been applied to a central challenge in materials science, the design of new functional materials with enhanced performance for targeted applications, with some notable successes over the last twenty years. However, the immensity of the high-entropy design space remains a major impediment to discovering optimal compositions with tailored microstructures. Suites of high-throughput computational tools have been developed to address this problem, but there is a compelling need to inform these models with fast, economical, non-destructive, and versatile experimental guidance. In this work, we demonstrate mechanical resonance measurements can address this need. Mechanical resonance measurements enable the rapid, non-destructive assessment of materials created by novel syntheses and/or processes and provide high-accuracy determinations of elastic constants to directly benchmark models. We exemplify these capabilities on W-Ta-Cr-V-Hf and Mo-Nb-Ti-V-Zr refractory high-entropy alloys and suggest methodologies for the wider adoption and application of mechanical resonance measurements.

Patricia G. F. Matsubara, Tayana Conte

Over twenty years ago, the Software Engineering (SE) research community have been involved with Evidence-Based Software Engineering (EBSE). EBSE aims to inform industrial practice with the best evidence from rigorous research, preferably from systematic literature reviews (SLRs). Since then, SE researchers have conducted many SLRs, perfected their SLR procedures, proposed alternative ways of presenting their results (such as Evidence Briefings), and profusely discussed how to conduct research that impacts practice. Nevertheless, there is still a feeling that SLRs' results are not reaching practitioners. Something is missing. In this vision paper, we introduce Evidence to Decision (EtD) frameworks from the health sciences, which propose gathering experts in panels to assess the existing best evidence about the impact of an intervention in all relevant outcomes and make structured recommendations based on them. The insight we can leverage from EtD frameworks is not their structure per se but all the relevant criteria for making recommendations to practitioners from SLRs. Furthermore, we provide a worked example based on an SE SLR. We also discuss the challenges the SE research and practice community may face when adopting EtD frameworks, highlighting the need for more comprehensive criteria in our recommendations to industry practitioners.

Simone Anzellini, Pablo Botella, Jose Luis Rodrigo-Ramon et al.

Abstract Transition metals, including Iridium, are crucial for understanding planetary cores and developing critical technologies due to their unique properties under extreme high-pressure and high-temperature conditions. Although Ir’s room-temperature phase remains stable, its pressure-temperature phase diagram is largely unknown, with only a single experimental melting point reported previously. A notable gap in knowledge is the lack of experimental evidence for solid-solid phase transitions predicted by theoretical models. Here we show a new investigation into the phase diagram of iridium, employing a combination of resistive-heated and laser-heated diamond anvil cells coupled with synchrotron X-ray diffraction. Our findings confirm that Ir maintains its face-centered cubic structure up to 101 GPa and 5600 K. We determined five new melting points that corroborate computational predictions, providing a more robust foundation for the melting curve. The resulting thermal equation of state offers a definitive dataset that can serve as a reliable pressure standard and advance the design of technologies using Ir.

Patrick Imrie, Jianyong Jin

Abstract 4D bioprinting is a groundbreaking technology with potential to revolutionize healthcare. It is based on additive manufacturing technologies, which are used to fabricate dynamic prosthetics and devices from biologically compatible smart materials that respond to stimuli. The ultimate end of 4D bioprinting is the creation of an artificial organ that perfectly mimics the functional movements of a native organ and is fully integrated within the human body. In this perspective, two phases are identified toward this end. The first is minimally invasive surgery (MIS) using shape memory composites stimulated by near‐infrared (NIR) light and/or magnetic fields. The second is dynamic tissue engineering (DTE) with activation by biological stimuli.

Pooja Kumari, Chandan Saha, Mustafizur Hazarika et al.

ABSTRACT The growing demand for improved energy storage solutions has increasingly intensified the focus on developing high‐performance electrode materials. In this context, hybrid nanocomposites that integrate polymers and metal nanoparticles have emerged as potential materials for next‐generation energy storage devices. In this study, a thiophene‐derivatized polyaniline‐silver nanoparticle hybrid system (Ag‐TdPA) was synthesized through an in situ synthesis route. The resulting material was employed in the fabrication of a supercapacitor device and further utilized in an oscillator application. Electrochemical studies demonstrated a specific capacitance of 660 and 94 F.g−1 for three‐electrode and two‐electrode (device) systems, made by Ag‐TdPA, at a current density of 4.0 and 0.5 A.g−1, with the capacitance retention of 97 and 92% at 8.0 and 1.0 A.g−1, respectively, after 5000 repetitive charge–discharge cycles. The device delivered up to 37 Wh.kg−1 of energy density and 3784 W.kg−1 of power density, demonstrating its potential for energy storage applications. The Ag‐TdPA‐based device was implemented in a low‐frequency relaxation oscillator, delivering a consistent output signal at 0.47 Hz. The dual functionality of Ag‐TdPA highlights the potential as an advanced material for energy storage and signal generation in low‐power electronic systems.

Wenjuan Zhou, Can Yang, Niutao Hu

Nikhil Prabhu, Martin Diehl

The efforts associated with parametrization of continuum-based models for crystal plasticity are a significant obstacle for the routine use of these models in materials science and engineering. While phenomenological constitutive descriptions are attractive due to their small number of adjustable parameters, the lack of physical meaning of their parameters counteracts this advantage to some extent. This study shows that interaction/strengthening coefficients determined with the help of discrete dislocation dynamics simulations for use in physics-based formulations can also be used to improve the predictive quality of phenomenological models. Since the values of these parameters have been determined for most technologically relevant materials, the findings enable to improve the parametrization of phenomenological crystal plasticity models at no costs.

Xing Wang, Edan Bainglass, Miki Bonacci et al.

Despite the wide availability of density functional theory (DFT) codes, their adoption by the broader materials science community remains limited due to challenges such as software installation, input preparation, high-performance computing setup, and output analysis. To overcome these barriers, we introduce the Quantum ESPRESSO app, an intuitive, web-based platform built on AiiDAlab that integrates user-friendly graphical interfaces with automated DFT workflows. The app employs a modular Input-Process-Output model and a plugin-based architecture, providing predefined computational protocols, automated error handling, and interactive results visualization. We demonstrate the app's capabilities through plugins for electronic band structures, projected density of states, phonon, infrared/Raman, X-ray and muon spectroscopies, Hubbard parameters (DFT+$U$+$V$), Wannier functions, and post-processing tools. By extending the FAIR principles to simulations, workflows, and analyses, the app enhances the accessibility and reproducibility of advanced DFT calculations and provides a general template to interface with other first-principles calculation codes.

Yingshuo Li, Minghou Li, Lanxin Wang et al.

With the rapid development of the aviation industry, airport pavement is subjected to ever-increasing loads, posing urgent and higher demands on the mechanical performance and durability of pavement materials. This study develops a novel Ultra-High Performance Concrete (UHPC) with outstanding mechanical properties, good workability, low curing maintenance, and excellent performance in sustaining long-term load to specially designed for its potential application in airport pavement. The as-developed UHPC contains a mixed portion of fine and coarse aggregate, assuring its workability and avoiding the early-age shrinkage crack for the potential on-site construction. With a 7-day compressive strength of 140 MPa, compressive strength of 155.1 MPa, flexural strength of 25.4 MPa at 28 days, and a wear loss per unit area of 0.043 kg/m2, the mechanical properties of UHPC well outperform those of conventional C30 airport pavement concrete. Finite element simulation analysis reveals that a 10 cm thick UHPC surface layer demonstrates durability and safety under aircraft taxiing and landing impact loads, with a maximum tensile stress of 4.12 MPa well below its tensile strength limit of 8.75 MPa. Furthermore, it is predicted that a 10 cm thick UHPC overlay could support a load cycle lifespan 1014 times longer than that of conventional C30 concrete of 30 cm thickness, indicating its potential to significantly extend the service life of airport pavement. This research provides a theoretical basis for the applications of UHPC in airport pavement and presents innovative perspectives on into material and structural design of airport pavement materials for the future.

Jolanta Konieczkowska, Klaudia Nocoń-Szmajda, Agnieszka Ciemięga

The paper presents the photomechanical effect generated in new azo side-chain polyimides synthesized through a post-functionalization strategy involving the Mitsunobu reaction. Prepared azo polyimide foils were irradiated by a 405 nm diode-laser beam (intensity, I = 100 mW/cm2; polarization, Eǀǀx) for the generation of the photomechanical effect. Despite the low content of azo chromophore (substitution of the hydroxyl group was in the range of 7–35%) and thick cantilevers (thickness ~35 μm), bending angles were in the range of 30–40°. Thermal unbending was not observed for 12 months after turning off the excitation light. Our investigation showed that, despite the low content of azo chromophore, it is possible to achieve photodeformation under polarized light. To the best of our knowledge, this is the first example of the photomechanical response of azo pyridine polymers.

Vikas Kumar, Km. Preeti, Vikram Saini et al.

Developing efficient micro-/nano-enabled sensing platforms based on the 5th and 6th generation is an escalating field where the data can be collected, transferred, and analyzed using AI and IoT systems in point-of-care (POC) situations. For personalized health, detecting low-concentration biomarkers requires highly efficient sensing electrodes. Interdigitated electrodes (IDEs)-based biosensors show promise due to their integration with microelectronics and ability for health monitoring. Systematic exploration of innovative designs, fabrication techniques, and surface chemistry is key to overcoming challenges and enabling efficient biosensing. This article explores IDEs’ potential in the early detection of diseases like cancer, COVID-19, and diabetes and discusses future directions.

Jun-Lin Zhan, Wei-Bing Lu, Cong Ding et al.

Abstract Wireless imaging, equipped with ultralow power wireless communications and energy harvesting (EH) capabilities, have emerged as battery-free and sustainable solutions. However, the challenge of implementing wireless colour imaging in wearable applications remains, primarily due to high power demands and the need to balance energy harvesting efficiency with device compactness. To address these issues, we propose a flexible and wearable battery-free backscatter wireless communication system specially designed for colour imaging. The system features a hybrid RF-solar EH array that efficiently harvests energy from both ambient RF and visible light energy, ensuring continuous operation in diverse environments. Moreover, flexible materials allow the working system to conform to the human body, ensuring comfort, user-friendliness, and safety. Furthermore, a compact design utilizing a shared-aperture antenna array for simultaneous wireless information and power transfer (SWIPT), coupled with an optically transparent stacked structure. This design not only optimizes space but also maintains the performance of both communication and EH processes. The proposed flexible and wearable systems for colour imaging would have potentially applications in environmental monitoring, object detection, and law enforcement recording. This approach demonstrates a sustainable and practical solution for the next generation of wearable, power-demanding devices.

Sanatan Halder, Debojit Chanda, Dibyendu Mondal et al.

Since its invention by Arthur Ashkin and colleagues at Bell Labs in the 1970s, optical micromanipulation, also known as optical tweezers or laser tweezers, has evolved remarkably to become one of the most convenient and versatile tools for studying soft materials, including biological systems. Arthur Ashkin received the Nobel Prize in Physics in 2018 for enabling these extraordinary scientific advancements. Essentially, a focused laser beam is used to apply and measure minuscule forces from a few piconewtons to femtonewtons by utilizing light-matter interaction at mesoscopic length scales. Combined with advanced microscopy and position-sensing techniques, optical micromanipulations enable us to investigate diverse aspects of functional soft materials. These include studying mechanical responses through force-elongation measurements, examining the structural properties of complex fluids employing microrheology, analyzing chemical compositions using spectroscopy, and sorting cells through single-cell analysis. Furthermore, it is utilized in various soft-matter-based devices, such as laser scissors and optical motors in microfluidic channels. This chapter presents an overview of optical micromanipulation techniques by describing fundamental theories and explaining the design considerations of conventional single-trap and dual-trap setups as well as recent improvisations. We further discuss their capabilities and applications in probing exotic soft-matter systems and in developing widely utilized devices and technologies based on functional soft materials.

Dezhi Ran, Mengzhou Wu, Wei Yang et al.

By treating data and models as the source code, Foundation Models (FMs) become a new type of software. Mirroring the concept of software crisis, the increasing complexity of FMs making FM crisis a tangible concern in the coming decade, appealing for new theories and methodologies from the field of software engineering. In this paper, we outline our vision of introducing Foundation Model (FM) engineering, a strategic response to the anticipated FM crisis with principled engineering methodologies. FM engineering aims to mitigate potential issues in FM development and application through the introduction of declarative, automated, and unified programming interfaces for both data and model management, reducing the complexities involved in working with FMs by providing a more structured and intuitive process for developers. Through the establishment of FM engineering, we aim to provide a robust, automated, and extensible framework that addresses the imminent challenges, and discovering new research opportunities for the software engineering field.

Yu-Chiang Hsieh, Zhen-You Lin, Shin-Ji Fung et al.

Strain engineering has quickly emerged as a viable option to modify the electronic, optical and magnetic properties of 2D materials. However, it remains challenging to arbitrarily control the strain. Here we show that by creating atomically-flat surface nanostructures in hexagonal boron nitride, we achieve an arbitrary on-chip control of both the strain distribution and magnitude on high-quality molybdenum disulfide. The phonon and exciton emissions are shown to vary in accordance with our strain field designs, enabling us to write and draw any photoluminescence color image in a single chip. Moreover, our strain engineering offers a powerful means to significantly and controllably alter the strengths and energies of interlayer excitons at room temperature. This method can be easily extended to other material systems and offers a promise for functional excitonic devices.

Ali H. AlAteah

LIU Hongxu, HOU Xuru, LIU Feng et al.

Two arc welding modes of melt inert gas welding (MIG) and cold metal transition + pulse welding (CMT+P) were used to weld 20 mm thick 7A52 aluminum alloy. The effects of different arc welding modes on the microstructure and mechanical properties of welded joints were studied from the aspects of welding defects, grain size and precipitation. The results show that the two welded joints are well formed and have no obvious defects. The weld microstructure is as cast equiaxed dendrite. Strip or block iron rich impurity phases AlFeMn and Mg2Si and Al3Mg2 phase with non coherent relationship with the α(Al) matrix are found in the weld. However, the porosity of MIG welding weld area is 2.73%, while that of CMT+P welding weld area is only 0.64%. At the same time, the weld grain size is small, the width of heat affected zone is narrow and the grain boundary segregation is small in CMT+P mode, so the joint strength in CMT+P mode is higher, with about 289 MPa. The pull-down fracture of the two modes is characterized by ductile fracture with dimples as the main feature.

L.-X. Fan, N. Han, Y. Zhang

<p>In the machining of monolithic components, machining distortion is a severe issue. The presence of initial residual stress is a major contributor to machining distortion. This paper proposes an approach to control the machining distortion of long beam parts by optimizing the workpiece structure before the start of the finishing stage, i.e. the transition structure. The first step is to establish a machining distortion analytical model for long beam parts with an identical cross-section, which is based on reasonable assumptions such as material linear elasticity and ignoring the influence of cutting heat. Then, an optimization model for the cross-section of the transition structure is developed, with the objective function defined as the minimum difference between the predicted distortion of the final part and the transition structure. Finally, a U-shaped beam is designed, followed by numerical simulation and machining experiments for verification. The theoretical maximum distortion of the optimized transition structure and the final part are <span class="inline-formula">−0.174</span> and <span class="inline-formula">−0.1782</span> mm, respectively, with a relative error of 2.9 %. The results of machining experiments and finite-element simulation demonstrate the effectiveness of the proposed model.</p>

Peng Wu, Xiyalatu Sai, Zhetao Li et al.

Induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) have an irreplaceable role in the treatment of myocardial infarction (MI), which can be injected into the transplanted area with new cardiomyocytes (Cardiomyocytes, CMs), and improve myocardial function. However, the immaturity of the structure and function of iPSC-CMs is the main bottleneck at present. Since collagen participates in the formation of extracellular matrix (ECM), we synthesized nano colloidal gelatin (Gel) with collagen as the main component, and confirmed that the biomaterial has good biocompatibility and is suitable for cellular in vitro growth. Subsequently, we combined the PI3K/AKT/mTOR pathway inhibitor BEZ-235 with Gel and found that the two combined increased the sarcomere length and action potential amplitude (APA) of iPSC-CMs, and improved the Ca2+ processing ability, the maturation of mitochondrial morphological structure and metabolic function. Not only that, Gel can also prolong the retention rate of iPSC-CMs in the myocardium and increase the expression of Cx43 and angiogenesis in the transplanted area of mature iPSC-CMs, which also provides a reliable basis for the subsequent treatment of mature iPSC-CMs.