Crack growth is a primary failure mechanism in engineering structures, and its real-time monitoring is critical for reliable damage evaluation and life prediction. In this study, a customizable crack monitoring sensor array is developed using direct ink writing (DIW) technology. The sensing concept translates crack-induced mechanical rupture into discrete, stepwise resistance variations, providing a direct and unambiguous electrical signature of crack initiation and propagation in real time. Here, the real-time capability refers to the synchronous electrical response triggered by fracture events, rather than high-speed temporal resolution. Owing to the high design flexibility of DIW, the sensor architecture can be readily tailored in terms of geometry, signal response, and system integration. Experimental validation demonstrates the capability of the proposed sensor to monitor multiple crack modes, including quasi-static fracture, dynamically unstable brittle fracture, fatigue crack growth, and crack-path deflection, across different substrate materials. The results highlight the effectiveness of the DIW-fabricated sensor array as a versatile and scalable platform for event-based, multi-mode crack monitoring in structural health monitoring applications.
The extraordinary mechanical properties of additive manufactured two-scale lattice structures can be substantially enhanced by employing optimisation techniques at both macroscopic and microscopic scales. Nonetheless, maintaining structural strength in designs that simultaneously incorporate complicated macroscopic and microscopic configurations presents a significant challenge. In this study, a two-scale topology optimisation method with microscopic stress constraints is proposed to find a two-scale structure with maximised stiffness while making the microscopic stress satisfy specified strength criteria. Herein, a two-scale structural stress characterisation based on the microscopic characterised stress field is firstly established to avoid the great computational effort caused by microscopic stress analysis at every macroscopic localisation. Then, a two-scale stress-constrained aggregation strategy is proposed to reduce the vast number of stress constraints involved in two-scale optimisation. The sensitivities of the aggregated stress constraints are derived using the adjoint variable method, and the optimisation problem is solved using a gradient-based mathematical algorithm. Numerical examples illustrate the effect of the stress constraints by comparing the optimisation results with and without microscopic stress constraints. Finally, specimens optimised using the proposed method are realised through additive manufacturing, and the results are further validated by testing stress distribution using a non-contact full-field strain measurement system.
French theater, which crystallizes a collective imaginary of fluids prevalent in the 19th century, sometimes acts as a relay for—or even manufactures—scientific inventions that may seem fanciful to the contemporary mind. Barrière and Sardou’s “electro-medical chains”, Georges Feydeau’s “ecstatic armchair” or André de Lorde’s “electrifying spike” are some of the devices put on stage to accentuate the blurring between scientific reality and theatrical illusion in a period brimming/overflowing with discoveries. These inventions also bring up issues of the moment (the bourgeois quest for pleasure, relations between the sexes and the excesses of modernity), while also revealing the changing face of science in the second half of the century.
Chakule Rahul R., Chaudhari Sharad S., Chandratre Kailas V.
et al.
The lubrication is a prime requirement of metal cutting industries to assure high quality performance. The conventional technique of coolant flow is less economical and eco-friendly. Recently, nano fluids found better cutting fluid in machining due to potential thermal and heat transfer properties. The role of micro-lubrication techniques and process optimization are equally important for improving process performance. The literature review presents the findings of different researchers in the field of nano fluids and micro-lubrication techniques. The experimental studies were focused on better process performance using micro-lubrication techniques, especially nanofluid MQL with optimized process parameters. The thermal conductivity of water based TiO2 nano fluid shows improvement by 22% in base fluids. The case study discussed which is focused on preparation and characterization of nano fluid, experimental setup and optimization of process parameters by Jaya algorithm. Finally, application of nano fluid, and challenges during nano fluid preparation is identified. The scope of research work is recommended for further study to obtain an economical, eco-friendly manufacturing process.
Purpose – The study has a twofold purpose. The first purpose is to understand the impact of the Covid-19 pandemic on women's work–home integration and stress from both a constructivist and positivist perspective. The other purpose is to emphasize the need for enterprises to understand the embedded considerations of occupational stress of women for strategy formulation. Design/methodology/approach – The study has used a convergent parallel design to obtain data. A total of 63 respondents (a survey with a sample of 53 and ten narratives) was identified using the snowball technique. The respondents were married and working professionals from Kerala. Perceived stress scale was used to procure data on their stress in the home-based work during the pandemic lockdown. Simultaneously narratives were taken from ten respondents from the same pool. The data were analyzed using R software version 4.0.2. Findings – The findings reflect that home-based work was stressful for women, and they weighed home tasks over work needs. There was no age difference in perceived stress, while it significantly differed by profession and designation they hold. Also, a mother felt more stressed than a non-mother. Quantitative data heavily backed up the narratives. Of the sample, 76% experienced higher stress levels. Practical implications – This research will help users understand the stress distribution in women workers and how various sample characteristics influence stress. The enterprise could use this study to introduce a gender touch to their strategy. The study also adds value to the existing literature on home-based work during the pandemic. Originality/value – The study systematically measures the stress felt by women during home-based work using a perceived stress scale. The mixed approach to the study helps to gain a deep understanding of the topic. This study is an original contribution by the authors to the collection of home-based work and stress literature.
Business, Production management. Operations management
As one of fast-growth wood species, hybrid yellow poplar (YP-h, Liriodendron sino-americanum) has been extensively planted throughout of China, however, little is known about its properties and applicability in structural and nonstructural applications such as construction and furniture. The aim of this study was to evaluate the properties of YP-h and examine its differences with yellow poplar (YP, Liriodendron tulipifera). The average vessel diameter of YP-h (55 μm) was 19 % lower than YP (68 μm), but, the density of YP-h was 37 % higher than YP and the dimensional change in YP-h was higher than YP. Comparable tensile strength and flexural modulus were found in YP-h and YP, however, the flexural, shear, and impact strength of YP-h was 35 %, 40 %, and 55 % higher than those of YP, respectively. The drilling, mortising, and turning processability of YP-h were superior to those of YP. Compared to the gluing and coating performance of YP, YP-h had inferior gluing properties and equivalent coating performance. Therefore, hybrid yellow poplar can be an ideal candidate for yellow poplar to be utilized in construction and furniture.
Over the years, using adhesive joints in structural applications widespread all industrial domain, achieving an amazing current usage. This is due to the benefits that this technology is capable of providing to complex-shaped structures, both in aerospace and automotive applications. Indeed, new polyurethane adhesives are a recently fastening method. This newest adhesive types bid great advantages especially on damping, impact and fatigue which are critical characteristics in the transportation industry. Besides, the current bus manufactures use this adhesive kind to join doors' structures aluminium assembly. As like, the Tunisian automotive industry ICAR uses a one-component polyurethane for doors' structure assembly. Crack problems due to fatigue are evident in those areas since they are continuously stressed. Thereby, working on more understanding polyurethane fatigue performance we investigate over this work, the response of the assembly aluminium-alloy polyurethane adhesive joints using SLJ with two design's parameters sorted from a static study under five distinct load levels. To achieve this purpose, substrates' surfaces roughness with an arithmetic average of surface heights Ra ≈ 0.6 µm, was used. Bonded specimens with 1 mm adhesive thicknesses were manufactured and examined using cyclic fatigue testing. Furthermore, the obtained results are also compared with others from literature using epoxy adhesives. Worthy results are obtained rising the effectiveness of this adhesive's type in the transport industry.
Materials of engineering and construction. Mechanics of materials