In this paper, static and dynamic tensile tests were conducted on two kinds of polycarbonate (HL6157 and A1225BK), combined with the digital image correlation (DIC), for guiding the development of ...the battery pack of new energy vehicles. The mechanical properties of polycarbonate at low-speed (0.01/s) and high-speed (1/s, 100/s) tension were investigated and the microstructure of the fracture for polycarbonate at different speed tensions was also investigated. The fracture microstructure of two kinds of materials was also investigated in this paper. The tension results showed that as the strain rate increased, the yield strength and modulus increased, and the yield strength of the two materials increased by 30% under high-speed tension. In addition, the fracture strain increase was greater than 10% as the strain rate increased. Meanwhile, for polycarbonate, the strain rate increased, and the fracture toughness increased.
Abrasive waterjet machining was an effective method for cutting CFRP materials in various industries, while machining defects are inevitably observed especially for thick CFRP laminates due to the ...inherent characteristics of waterjet. In this work, a full factorial experimental array was employed totally involving 18 trials when using abrasive waterjet to cut CFRP laminate up to 10.0 mm thick. The influence of process parameters including hydraulic pressure, traverse speed, and stand-off distance on jet energy was deeply analyzed and the power-to-speed ratio (Ė/u) parameter was obtained, which was combined with the physical energy model of abrasive waterjet based on the energy method. The influence of process parameters on kerf characteristics/surface integrity and the mechanism of defects were further analyzed. Various surface defects along thickness direction were observed and corresponding mechanisms were investigated. Results showed that higher hydraulic pressure, lower traverse speed, and stand-off distance within in the selected range were preferred to obtain better surface quality. From the perspective of power-to-speed ratio (Ė/u), the surface roughness decreased rapidly up to ~ 68% with Ė/u increased from 20,000 to 40,000 J/m. When it exceeded 40,000 J/m, the downward trend gradually reduced and even became stable in the case of high stand-off distance. The level of kerf width generally increased with the increase of Ė/u irrespective of stand-off distance.
Owing to the native character of the coefficient of thermal expansion (CTE) mismatch between Al2O3 and 304 stainless steel, obtaining high strength for Al2O3/304 stainless steel joints remains ...challenging. In this study, the residual stress of an Al2O3/304 stainless steel brazed joint was relieved using the Ag‐Cu‐Ti + boron nitride (BN) composite filler. The results indicated that the elements between the filler and base metals on both sides were mutually diffused. Moreover, reaction layers formed at the interface, connecting the Al2O3 ceramic and 304 stainless steel. The microstructure of the joint was as follows: Al2O3/Cu3Ti3O + TiCu/Ag (s, s) + Cu (s, s) + TiN + TiB2 + TiCu/Cu0.8Fe0.2Ti/TiFe2/Fe‐Cr/304 stainless steel. When the .1 wt% BN was added, the average strength of the joint reached 151 ± 10 MPa, 15% higher than the average strength of the joint only using Ag‐Cu‐Ti filler (131 ± 9 MPa). The improvement in the shear strength and reduction in the residual stress was attributed to the formation of TiN and TiB2, reducing the CTE difference and refining the microstructure.
This study aims to invigorate China's Rural Revitalization Strategy by focusing on the training of China's new generation of professional farmers, particularly enhancing the skills of modern ...agricultural practitioners. Utilizing a mixed-method research approach, which includes the analysis of 343 questionnaire surveys and personal interviews, significant shortcomings in the previous training of farmers were revealed, such as limited reach, high conformity in training content, and outdated methods. These findings highlight the challenges traditional training methods face in the digital technology era. In response to these challenges, this study proposes a novel training model designed for the digital era. This model encompasses seven aspects: training goals, subjects, content, means, management, methods, and effect assessment, with the aspiration to reform traditional farmer training methods. This research expands the existing literature by constructing a comprehensive framework for training the new generation of farmers, bridging the gap between traditional practices and the demands of modern agricultural training influenced by digital advancements. The study's innovation lies in its proposition of a modernized training model for the new generation of farmers, leveraging the advancements of the digital technology era. By modernizing agricultural training and enhancing the capabilities of new professional farmers, it significantly contributes to the progression of China's Rural Revitalization Strategy.
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Decarbonising tourism is an immeasurable challenge but increasingly recognised as inevitable. This has prompted vast developments in theoretical models by academics and indicators by peak bodies to ...explore the pathways. One limitation to the pathways is the lack of emission data. This research presents a framework integrating the principles of TSA with the National Greenhouse Accounts. Tourism emissions are estimated and examined by destinations, producing industries and visitor types. The framework is applied to destinations in the State of Queensland, Australia, to illustrate the types of results and insights that can be produced for decision-makers. Mitigation policies can then be tailored to the specific context of each destination, increasing effectiveness and ability to balance economic benefits with reducing emissions.
•TSA, IO tables & national GHG accounts are integrated to develop tourism emissions.•Tourism Emissions are consistent with the national accounts and emission accounts.•Emissions are presented by destination, producing industry & visitor type.•Data are essential for developing decarbonisation tourism policies.•Framework can be replicable to other countries with similar data sources.
•First study on mediated bacterial azo dye decolorization under saline conditions.•Quinone respiration of marine Shewanella strains under saline conditions.•Detailed studies of different effects of ...various quinones on decolorization.•Study of rate-limiting step of mediated decolorization under saline conditions.
Azo dye decolorization by Shewanella algae (SAL) in the presence of high concentrations of NaCl and different quinones or humic acids was investigated to reveal the effects of redox mediator under saline conditions. Growth of SAL and the other two marine Shewanella strains coupled to anthraquinone-2,6-disulfonate (AQDS) reduction was observed in a wide range of NaCl concentrations (0–7%). AQDS showed the best enhancing effects, whereas some other quinones demonstrated poorer stimulating or even inhibiting effects on acid red 27 (AR27) decolorization. Different humic acids could also enhance the decolorization. The correlation between specific AQDS-mediated reduction rate and initial AR27 concentration could be described with Michaelis–Menten kinetics (Km=0.2mM and Vmax=9.3μmolmgcell−1h−1). AQDS reduction by SAL was determined to be the rate-limiting step of mediated reduction. Mediated decolorization products of AR27 were determined to be less phytotoxic aromatic amines.
Corrosion behavior is critical to the application of lightweight aluminum/steel joints using new resistance spot welding (RSW) technology. The study investigated the corrosion mechanism and the shear ...strength of RSW joints comprising 1.2 mm 5182 aluminum and 1.5 mm DP780 galvanized steel. Electrochemical corrosion tests were conducted on the base materials and various positions of the welds in a 3.5% NaCl solution. This result revealed that the corrosion susceptibility of the interfacial intermetallic compound (IMC) layer was not accelerated by the aluminum nugget because of the noble corrosion potential. Subsequently, the spray acceleration test was employed to investigate the corrosion mechanism. It is noteworthy that microcracks, as well as regions enriched with silicon and oxygen at the interface front, are preferential to corrosion during salt spray exposure, instead of the IMC layer. Moreover, the shear strength of the joints decreases with the reduction in the effective joint area after the salt spray exposure of the weld joints. This research systematically explored the corrosion behavior and its relationship with the mechanical properties of Al alloy/steel RSW joints.
Abstract
Interfacial intermetallic compound (IMC) layer is critical during realizing the galvanic corrosion mechanism and strength degradation of aluminium/steel resistance spot welding (RSW) joints. ...The effect of IMC layer on the corrosion behaviour of RSW joint between 5182 aluminium alloy and galvanized DP780 dual-phase steel was investigated by immersion corrosion method and electrochemical method. Results demonstrated localized corrosion around Fe-rich phase particles on aluminium nugget and preferential corrosion at the interface front near IMC layer. The IMC layer had the highest open circuit potential value of −0.569 V and low corrosion current density among the investigated nugget and substrates. The potential difference (0.184 V) between the cathodic IMC layer and large area of anodic aluminium nugget was responsible for the preferential initiation of localized corrosion at the interface front near the IMC layer.
The fracture performance and damage prediction of die-cast materials are critical to guarantee the safe application of die-cast structural components in lightweight vehicles. Monotonic loading ...experiments were conducted on different shapes of die-cast aluminum alloy A356 specimens. Finite element simulation models of the A356 monotonic loading experiments were established, and the stress state of the specimens during the loading process was analyzed. The Modified Mohr–Coulomb (MMC) failure model of A356 was fitted by the failure strain under different stress states. Finally, the established MMC failure model was verified by a uniaxial compression experiment and bending experiment. The results show that the MMC failure model can be applied to the prediction of the fracture behavior of A356.
In this study, the quasi-static and dynamic compressive mechanical behavior of a rolled Fe-28Mn-10Al-1.2C steel (low-density) was investigated. X-ray diffraction, optical microscopy, electron ...backscattered diffraction and transmission electron microscopy were conducted to characterize the microstructure evolution. The results displayed that the steel has remarkable strain rate sensitivity and strong strain hardenability under high strain rate compression. Most specifically, the deformation behavior was changed with the increase in the strain rate. A feasible mathematical analysis for the calculation of stacking fault energies and the critical resolve shear stresses for twinning was employed and discussed the nucleation of the twinning. The microband-induced plasticity and twinning-induced plasticity controlled the deformation under high strain rate compression and provided a strong strain hardening effect. The higher mechanical response can increase the broad use of low-density steel in automobile applications.
