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The interaction between rock mass structural planes and dynamic stress levels is important to determine the stability of rock mass structures in underground geotechnical engineering. In this work, the authors aim to focus on the degradation effects of fracture geometric parameters and unloading stress paths on rock mechanical properties.

A three-dimensional Particle Flow Code (PFC3D) was used for a systematic numerical simulation of the strength failure and cracking behavior of granite specimens containing prefabricated cracks under conventional triaxial compression and triaxial unilateral unloading. The authors demonstrated the unique mechanical response of prefabricated fractured rock under two conditions. The crack initiation, propagation, and coalescence process of pre-fissured specimens were analyzed in detail.

The authors show that the prefabricated cracks and unilateral unloading conditions not only deteriorate the mechanical strength but also have significant differences in failure modes. The degrading effect of cracks on model strength increases linearly with the decrease of the dip angle. Under the condition of true triaxial unilateral unloading, the deterioration effect of peak strength of rock is very significant, and unloading plays a role in promoting the instability failure of rock after peak, making the rock earlier instability failure. Associating with the particle vector diagram and crack coalescence process, the authors find that model failure mode under unilateral loading conditions is obviously distinct from that in triaxial loading. The peak strain in the unloading direction increases sharply, resulting in a new shear slip.

This study is expected to improve the understanding of the strength failure and cracking behavior of fractured rock under unilateral unloading.

The purpose of this paper is to study the effects of voltage on microstructure and properties of micro-arc oxidation (MAO) ceramic coatings formed on AZ31B magnesium alloy under the constant current–constant voltage operation mode.

The wear and corrosion resistance of MAO coating on AZ31B magnesium alloy was studied by MAO in silicate electrolyte under constant current and constant voltage.

When the voltage is 360 V, the wear and corrosion resistance of AZ31B magnesium alloy is the best.

The wear and corrosion resistance of MAO coating on AZ31B magnesium alloy was studied by friction wear and electrochemical workstation.

In recent years, fire accidents in engineering structures have often been reported worldwide, leading to a severe risk to life and property safety. The present study is carried out to evaluate the performance of Ground Granulated Blast Furnace Slag (GGBS) and fly ash–blended laterized mortars at elevated temperatures.

This test program includes the replacement of natural river sand with lateritic fine aggregates (lateritic FA) in terms of 0, 50 and 100%. Also, the ordinary Portland cement (OPC) was replaced with fly ash and GGBS in terms of 10, 20, 30% and 20, 40 and 60%, respectively, for producing blended mortars.

This paper presents results related to the determination of residual compressive strengths of lateritic fine aggregates-based cement mortars with part replacement of cement by fly ash and GGBS exposed to elevated temperatures. The effect of elevated temperatures on the physical and mechanical properties was evaluated with the help of microstructure studies and the quantification of hydration products.

A sustainable cement mortar was produced by replacing natural river sand with lateritic fine aggregates. The thermal strength deterioration features were assessed by exposing the control specimens and lateritic fine aggregates-based cement mortars to elevated temperatures. Changes in the mechanical properties were evaluated through a quantitative microstructure study using scanning electron microscopy (SEM) images. The phase change of hydration products after exposure to elevated temperatures was qualitatively analyzed by greyscale thresholding of SEM images using Image J software.

The purpose of this review is to comprehensively consider the material properties and processing of additive titanium alloy and provide a new perspective for the robotic grinding and polishing of additive titanium alloy blades to ensure the surface integrity and machining accuracy of the blades.

At present, robot grinding and polishing are mainstream processing methods in blade automatic processing. This review systematically summarizes the processing characteristics and processing methods of additive manufacturing (AM) titanium alloy blades. On the one hand, the unique manufacturing process and thermal effect of AM have created the unique processing characteristics of additive titanium alloy blades. On the other hand, the robot grinding and polishing process needs to incorporate the material removal model into the traditional processing flow according to the processing characteristics of the additive titanium alloy.

Robot belt grinding can solve the processing problem of additive titanium alloy blades. The complex surface of the blade generates a robot grinding trajectory through trajectory planning. The trajectory planning of the robot profoundly affects the machining accuracy and surface quality of the blade. Subsequent research is needed to solve the problems of high machining accuracy of blade profiles, complex surface material removal models and uneven distribution of blade machining allowance. In the process parameters of the robot, the grinding parameters, trajectory planning and error compensation affect the surface quality of the blade through the material removal method, grinding force and grinding temperature. The machining accuracy of the blade surface is affected by robot vibration and stiffness.

This review systematically summarizes the processing characteristics and processing methods of aviation titanium alloy blades manufactured by AM. Combined with the material properties of additive titanium alloy, it provides a new idea for robot grinding and polishing of aviation titanium alloy blades manufactured by AM.

This paper aims to focus on the research progress of intelligent self-healing anti-corrosion coatings in the aviation field in the past few years. The paper provides certain literature review supports and development direction suggestions for future research on intelligent self-healing coatings in aviation.

This mini-review uses a systematic literature review process to provide a comprehensive and up-to-date review of intelligent self-healing anti-corrosion coatings that have been researched and applied in the field of aviation in recent years. In total, 64 articles published in journals in this field in the last few years were analysed in this paper.

The authors conclude that the incorporation of multiple external stimulus-response mechanisms makes the coatings smarter in addition to their original self-healing corrosion protection function. In the future, further research is still needed in the research and development of new coating materials, the synergistic release of multiple self-healing mechanisms, coating preparation technology and corrosion monitoring technology.

To the best of the authors’ knowledge, this is one of the few systematic literature reviews on intelligent self-healing anti-corrosion coatings in aviation. The authors provide a comprehensive overview of the topical issues of such coatings and present their views and opinions by discussing the opportunities and challenges that self-healing coatings will face in future development.

This paper presents the outcomes of the international project “Protecting Landscape Heritage: a requalification project as an instrument for the re-birth of Quang Tri Old Citadel in Vietnam”, achieved with scientific cooperation between the Università Politecnica delle Marche (Italy) and Hue University of Sciences (Vietnam) funded by the Italian Ministry of Foreign Affairs and International Cooperation and Ministry of Science and Technology of Vietnam. The research focuses on the Quang Tri Citadel, founded in 1809 and now in an advanced state of degradation.

For the purpose of rehabilitation, the wide multidisciplinary project first examined the historical context of the military model, the architectural aspects of the structure, the characterization of the existing materials, the degradation levels of different parts, and, finally, a proposal of the suggested interventions.

The original structure and geometry were extrapolated and studied. Building materials were produced with nearby raw materials. Firing temperatures of bricks ranged from 800 to 1,000 °C, hydraulic lime was supposed the binder of the mortar with a calcination temperature lower than 1,000 °C. Damage assessment was provided and after these analyses a requalification project was proposed so the cultural heritage can play a role for the future in the dialog between different cultures.

The requalification project achieved by an integrated analytical approach defines aspects in relation to the restoration of the structures, enabling compliance with the geometry, techniques, building materials used in the original construction and allowing its guardianship and management to align with the historical context of the architectural heritage.

The purpose of this study is to investigate the behaviour of M40 grade of self-compacting concrete (SCC) with high volume of ground granulated blast furnace slag (GGBS) (50%) and recycled concrete aggregate (RCA) content up to 100% to assess the mechanical properties of SCC. As per guidelines of IS: 383 – 2016, the RCA can be replaced up to 20% of natural coarse aggregate up to M25 grade of concrete. This study assesses the mechanical properties of SCC beyond 20% of RCA content. Based on the experimental investigations, the compressive strength of mixes decreases as the content of RCA increases. It is found that concrete mixes with 20% RCA and shows the maximum compressive strength at 56 days.

The fresh properties as per EFNARC and IS: 10262–2019 guidelines, ultrasonic pulse velocity testing, mechanical properties and microstructure analysis have been conducted to evaluate the performance of SCC with RCA for practical applications.

From the experimental investigations, it is found that up to 50% of recycled coarse aggregate can be used for structural applications.

The environmental pollution and dumping of waste on green land can be reduced by effective utilization of recycled coarse aggregate and GGBS in the production of SCC.

The majority of previous studies made on Recycled Concrete Aggregates (RCA) are limited to the utilisation of non-structural grade concrete due to unfavourable physical characteristics of RCA including the higher absorption of water, tending to increased water requirement of concrete. This seriously limits its applicability and as a result it reduces the usage of RCA in structural members. In the present study, the impact of hybrid fibres on cracking behaviour of RCA concrete beams along with the inclusion of reinforcing steel bars under two-point loading system exposed to different sustained elevated temperatures are being investigated.

RCA is substituted for Natural Coarse Aggregates (NCA) at 0, 50 and 100 percentages. The study involves testing of 150 mm cubes and beams of size (700 × 150 × 150) mm, i.e. with steel reinforcing bars along with the addition of 0.35% Steel fibres+ 0.15% polypropylene fibres. The specimens are being exposed to temperatures from 100° to 500°C with 100° interval for 2 h. Studies were made on the post crack analysis, which includes the measurement of crack width, crack length and load at first crack. The crack patterns were analysed in order to understand the effect of fibres and RCA at sustained elevated temperatures.

The result shows that ultimate load carrying capacity of reinforced concrete beams and load at first crack decreases with the raise in temperatures and increased percentage of RCA content in the mix. Further that 100% RCA replacement specimens showed lesser cracks when compared to the other mixes and the inclusion of fibres enhances the flexural capacity of members highlighting the importance of fibres.

RCA can be used for structural purposes and the study can be projected for assessing the performance of real structures with the extent of fire damage when recycled aggregates are used.

Most of recycled materials can be used in the regular concrete which solves two problems namely avoiding the dumping of C&D waste and preventing the usage of natural aggregates. Hence the study provides sustainable option for the production of concrete.

The reduction in capacity of flexural members due to the utilisation of recycled aggregates can be negated by the usage of fibres. Hence improved flexural performance is observed for specimens with fibres at sustained elevated temperatures.

This paper aims to report the effect of titanium oxide (TiO₂) particles on the physical, mechanical, tribological and water resistance properties of 5% NaOH-treated bamboo fiber–reinforced composites.

In this research, the epoxy/bamboo/TiO₂ hybrid composite filled with 0–8 Wt.% TiO₂ particles has been fabricated using simple hand layup techniques, and testing of the developed composite was done in accordance with the American Society for Testing and Materials (ASTM) standard.

The results of this study indicate that the addition of TiO₂ particles improved the mechanical properties of the developed epoxy/bamboo composites. Tensile properties were found to be maximum for 6 Wt.%, and impact strength was found to be maximum for 8 Wt.% TiO₂ particles-filled composite. The highest flexural properties were found at a lower TiO₂ fraction of 2 Wt.%. Adding TiO₂ filler helped to reduce the water absorption rate. The studies related to the wear and friction behavior of the composite under dry and abrasive wear conditions reveal that TiO₂ filler was beneficial in improving the wear performance of the composite.

This research paper attempts to include both TiO₂ filler and bamboo fibers to develop a novel composite material. TiO₂ micro and nanoparticles are promising filler materials; it helps to enhance the mechanical and tribological properties of the epoxy composites and in literature, there is not much work reported, where TiO₂ is used as a filler material with bamboo fiber–reinforced epoxy composites.

This study aims to investigate crack propagation in a moisture-preconditioned soft-termination multi-layer ceramic capacitor (MLCC) during thermal reflow process.

Experimental and extended finite element method (X-FEM) numerical analyses were used to analyse the soft-termination MLCC during thermal reflow. A cross-sectional field emission scanning electron microscope image of an actual MLCC’s crack was used to validate the accuracy of the simulation results generated in the study.

At 270°C, micro-voids between the copper-electrode and copper-epoxy layers absorbed 284.2 mm/mg³ of moisture, which generated 6.29 MPa of vapour pressure and caused a crack to propagate. Moisture that rapidly vaporises during reflow can cause stresses that exceed the adhesive/substrate interface’s adhesion strength of 6 MPa. Higher vapour pressure reduces crack development resistance. Thus, the maximum crack propagation between the copper-electrode and copper-epoxy layers at high reflow temperature was 0.077 mm. The numerical model was well-validated, as the maximum crack propagation discrepancy was 2.6%.

This research holds significant implications for the industry by providing valuable insights into the moisture-induced crack propagation mechanisms in soft-termination MLCCs during the reflow process. The findings can be used to optimise the design, manufacturing and assembly processes, ultimately leading to enhanced product quality, improved performance and increased reliability in various electronic applications. Moreover, while the study focused on a specific type of soft-termination MLCC in the reflow process, the methodologies and principles used in this research can be extended to other types of MLCC packages. The fundamental understanding gained from this study can be extrapolated to similar structures, enabling manufacturers to implement effective strategies for crack reduction across a wider range of MLCC applications.

The moisture-induced crack propagation in the soft-termination MLCC during thermal reflow process has not been reported to date. X-FEM numerical analysis on crack propagation have never been researched on the soft-termination MLCC.