Interfacial Characteristics Research Articles

Achieving BNNSs intrinsic strengthening in Ti-based composite through reaction-interface engineering

For the purpose of achieving boron nitride nanosheets (BNNSs) intrinsic strengthening and relating microscopic interface characteristics to macroscopic mechanical behavior in BNNSSs/Ti composites, the BNNSs/Ti composites were fabricated by field-assisted hot pressing (FHP) and subsequent 923K, 1023K, 1123K or 1223K hot-rolling (HR). Herein, we succeeded in simultaneously maintaining the BNNSs intrinsic structure and considerable interfacial nano-sized TiBw. Interestingly, the superior tensile property (UTS: 1166MPa, El. 9.3%) was realized in 1123K as-rolled BNNSs/Ti composite, whereas the dramatic ductility deterioration exhibited in composite when the HR temperature setting at 1223K. BNNSs load transfer and interface failure behavior were investigated by direct in-situ tensile SEM observation. The nano-TiBw on partially reacted BNNSs played a predominant role on BNNSs load-transfer efficiency and contributed to the desirable ductility. These findings highlighted the untapped potential for improving mechanical properties in BNNSs reinforced metal matrix composite.

Study on interface characteristics and electron spin manipulation of two-dimensional [formula omitted] (001) heterostructures

Among numerous strongly correlated electron materials, cobalt ions in perovskite oxide SrCoO3 (SCO) possess rich valence states, playing a crucial role in determining the functionality of the material. Meanwhile, thin film preparation techniques such as epitaxial growth and pulsed laser deposition have accelerated the research progress of two-dimensional SCO films. In this study, we primarily investigate the interface characteristics and electron spin of two-dimensional SrCoO3/LaAlO3 (SCO/LAO) (SCO/LAO) (001) heterostructures using density functional theory, revealing the influence of atomic layer thickness and doping on the heterostructure. Our research results indicate that SCO/LAO heterostructures exhibit metallic behavior and ferromagnetism, and doping with oxygen vacancies and Nb2+ ions leads to significant changes in electronic properties and magnetism of the heterostructure. These findings provide insights for the experimental synthesis of two-dimensional heterostructures and suggest that two-dimensional SCO/LAO (001) heterostructures possess rich interface properties with tremendous potential applications in electronic devices.

Optimization of mechanical and safety properties by designing interface characteristics within energetic composites

The interfacial structure has an important effect on the mechanical properties and safety of the energetic material. In this work, a mesostructure model reflecting the real internal structure of PBX is established through image digital modeling and vectorization processing technology. The microscopic molecular structure model of PBX is constructed by molecular dynamics, and the interface bonding energy is calculated and transferred to the mesostructure model. Numerical simulations are used to study the influence of the interface roughness on the dynamic compression and impact ignition response of PBX, and to regulate and optimize the mechanical properties and safety of the explosive to obtain the optimal design of the surface roughness of the explosive crystal. The results show that the critical hot spot density of PBX ignition under impact loading is 0.68 mm−2. The improvement of crystal surface roughness can improve the mechanical properties of materials, but at the same time it can improve the impact ignition sensitivity and reduce the safety of materials. The optimal friction coefficient range for the crystal surface that satisfies both the mechanical properties and safety of PBX is 0.06–0.12. This work can provide a reference basis for the formulation design and production processing of energetic materials.

Supraspinatus Tendon Reconstruction Versus the Bridging Technique in a Rat Model: Histological, Biomechanical, and Functional Outcomes

Background: Massive irreparable rotator cuff tears (MIRCTs) are among the most challenging shoulder conditions to treat surgically. Supraspinatus tendon reconstruction (STR) is a recently introduced technique for MIRCTs based on fascia lata-muscle interface healing, which completely differs from the classic bridging technique with fascia lata-tendon interface healing. However, histological and biomechanical comparisons of the fascia-muscle and fascia-tendon interfaces have not been performed. Purpose: To investigate the histological and biomechanical healing of the fascia-bone interface and fascia-muscle interface after chronic MIRCTs in a rat model using different surgical methods. Study Design: Controlled laboratory study. Methods: The authors established a chronic MIRCT model in the right shoulder of rats and then repaired it using the STR or bridging repair technique. Evaluations were performed at 2, 4, 8, and 12 weeks, including histological, imaging, biomechanical, and functional analyses. Results: Both techniques resulted in good fascia-bone interface healing based on the histological results. The STR group had significantly more cartilage formation at 8 and 12 weeks and higher Modified Tendon Maturity Score after 12 weeks at the fascia-bone interface compared with the bridging repair group and formed the typical 4-layered structure. Collagen fibers in the fascia-muscle and fascia-tendon interfaces exhibited normal muscle-tendon interface characteristics at 12 weeks. However, the STR group had more improvement in fatty infiltration compared with the bridging repair group. The ultimate failure load and stiffness did not differ between the STR and bridging repair groups 4 weeks postoperatively in both the fascia-bone interface and supraspinatus muscle-fascia-bone integrity. Movement distance and grasp time were significantly longer in the STR group than in the bridging repair group at 12 weeks and attached the level in the normal control groups. Conclusion: These results suggest that the fascia-muscle interface from the STR technique is histologically and functionally better than the fascia-tendon interface. Moreover, this study provides a theoretical basis for the clinical use of the STR technique. Clinical Relevance: The fascia-muscle interface and fascia-tendon interface were the key points of the STR and bridging techniques, respectively. The fascia-muscle interface is histologically and functionally superior to the bridging technique, and the STR technique might be a better choice for the treatment of MIRCTs.

Overview of Inorganic Electrolytes for All-Solid-State Sodium Batteries.

All-solid-state sodium batteries (AS3B) emerged as a strong contender in the global electrochemical energy storage market as a replacement for current lithium-ion batteries (LIB) owing to their high abundance, low cost, high safety, high energy density, and long calendar life. Inorganic electrolytes (IEs) are highly preferred over the conventional liquid and solid polymer electrolytes for sodium-ion batteries (SIBs) due to their high ionic conductivity (∼10-2-10-4 S cm-1), wide potential window (∼5 V), and overall better battery performances. This review discusses the bird's eye view of the recent progress in inorganic electrolytes such as Na-β"-alumina, NASICON, sulfides, antipervoskites, borohydride-type electrolytes, etc. for AS3Bs. Current state-of-the-art inorganic electrolytes in correlation with their ionic conduction mechanism present challenges and interfacial characteristics that have been critically reviewed in this review. The current challenges associated with the present battery configuration are overlooked, and also the chemical and electrochemical stabilities are emphasized. The substantial solution based on ongoing electrolyte development and promising modification strategies are also suggested.

Insight on Interfacial Microstructure and Corrosion Characteristics of Mg/Al Explosive Welded Composite Plates

Interfacial corrosion performance is crucial to the reliability of Mg/Al explosively welded composite plates. Nevertheless, more understanding is required concerning such interfacial corrosion. In this work, a combination of numerical simulation and experimental investigation was used to clarify the microstructure evolutions of AZ80‐Mg alloy/1060‐Al explosively welded composite plate. The formation of interfacial wave structure and the thermodynamic state were insighted through numerical simulation, which further enhanced the correlation between the interfacial microstructural heterogeneities and the interfacial corrosion characteristics. Galvanic corrosion was produced by the significant potential difference between the AZ80‐Mg and 1060‐Al, with multiple micro‐galvanic couples in the vortex zone. The corrosion occurred near the interface and gradually advanced away from the interface. After 1 h, the composite plates exhibited severe corrosion with deep pits on the Mg side, while the Al side was less affected. Within the vortex, however, the Mg‐rich region underwent little corrosion, whereas the Al‐rich region underwent significant corrosion, attributed to the increase in pH value caused by the Mg corrosion.

Finite-discrete element modelling of fracture development in bimrocks

Block-in-matrix rocks (bimrocks) are a complex geological feature composed of hard blocks in a weak matrix bonded together via a weak interface. The failure mechanism and deformation behavior of the bimrocks is quite complex due to the simultaneous existence of blocks with different shapes, strengths and proportions in a matrix. Therefore, it is of great importance to characterize the bimrocks under different situations. This study employs the combined finite-discrete element method (FDEM) to characterize the failure pattern and load carrying capacity of the bimrocks considering changes in various parameters, including block size, volumetric block proportion (VBP), the strength ratio of block-matrix interface to matrix, and the shape of the blocks (angular, circular, and elliptical shapes). First, the robustness and feasibility of the FDEM in modeling fracture development is verified against an analytical solution as well as a series of experimental tests accompanied with the digital image correlation (DIC) method. Then, the verified model is used to model disc specimens with various block shapes and properties. The results indicate the remarkable influence of VBP, block size and block-matrix interface characteristics on the bimrock mechanical behavior under the same VBP. The results are assessed based on macroscopic observations to investigate the influence of determinative physical properties of bimrocks. The results are also evaluated based on the mode of failure, mode I, II, or mixed mode, to qualitatively elucidate the influence of key factors on the formation of different cracks in different places, including the interface of matrix-blocks or intergrain or intragrain. The results show that since the loading is a quasi-static scheme, all the cracks are intergrain and no intragrain crack is observed for any VBP. The simulations outcomes shows that the block sizes determine the failure pattern, failure mode, and load–displacement behavior, where the larger blocks exhibiting the lowest load carrying capacity due to experiencing more interface breakage in shear. It is found that the VBP is a crucial parameter in the deformation of the bimrocks, showing that the strength of the bimrocks significantly increases with a decrease in the VBPs and the ones with greater VBPs experience more breakage and thus less resistance to loading. The block-interface strength is found to be the most critical factor in the deformation of the bimrocks (regardless of the value of the VBP). Finally, the effect of block shape is shown to have a considerable impact on bimrocks with the higher VBPs (more than 70%).

Janus MoSH/WSi2N4 van der Waals Heterostructure: Two-Dimensional Metal/Semiconductor Contact.

Constructing heterostructures from already synthesized two-dimensional materials is of significant importance. We performed a first-principles study to investigate the electronic properties and interfacial characteristics of Janus MoSH/WSi2N4 van der Waals heterostructure (vdWH) contacts. We demonstrate that the p-type Schottky formed by MoSH/WSi2N4 and MoHS/WSi2N4 has extremely low Schottky barrier heights (SBHs). Due to its excellent charge injection efficiency, Janus MoSH may be regarded as an effective metal contact for WSi2N4 semiconductors. Furthermore, the interfacial characteristics and electronic structure of Janus MoSH/WSi2N4 vdWHs can not only reduce/eliminate SBH, but also forms the transition from p-ShC to n-ShC type and from Schottky contact (ShC) to Ohmic contact (OhC) through the layer spacing and electric field. Our results can offer a fresh method for optoelectronic applications based on metal/semiconductor Janus MoSH/WSi2N4 vdW heterostructures, which have strong potential in optoelectronic applications.

Temperature-Dependent Post-Cyclic Mechanical Characteristics of Interfaces between Geogrid and Marine Reef Sand: Experimental Research and Machine Learning Modeling

The mechanical response of the marine reef sand–geogrid (RG) interface can be influenced by a high-temperature climate, grain size, and variable stress environments. These factors are critical to the effectiveness of geogrid reinforcement in reef sand engineering. However, there are few studies on the influences of grain size, temperature, and stress history on the mechanical characteristics of RG interfaces, with most studies centering on the influence of single factors on the mechanical characteristics of RG interfaces. In this paper, based on self-developed temperature-controlled large interface shear equipment, a series of before/post-cyclic shear tests were carried out on RG interfaces in the temperature range of 5–80 °C. The impact of different reef sand grain sizes on the RG interface was explored (S1: 1–2 mm; S2: 2–4 mm). It was shown that temperature and grain size had significant influences on the mechanical characteristics of the RS interface. Compared with the S1 RG interfaces, the S2 RG interfaces had higher sensitivity to temperature changes with respect to the before/post-cyclic maximum shear strength. Moreover, in comparison to the before-cyclic shear strength, the post-cyclic maximum shear strength is more responsive to temperature changes. The before/post-cyclic maximum shear strength of the S2 RG interfaces was greater than the maximum shear strength of the S1 RG interfaces as the temperature changed. Based on the results of physical tests, a machine learning model containing 450 datasets was constructed, which can accurately predict the shear strength of the RG interface.

Research Progress in Corrosion Behavior and Anti-Corrosion Methods of Steel Rebar in Concrete

The corrosion of steel rebars is a prevalent factor leading to the diminished durability of reinforced concrete structures, posing a significant challenge to the safety of structural engineering. To tackle this issue, extensive research has been conducted, yielding a variety of theoretical insights and remedial measures. This review paper offers an exhaustive analysis of the passivation processes and corrosion mechanisms affecting steel rebars in reinforced concrete. It identifies key factors such as chloride ion penetration and concrete carbonization that primarily influence rebar corrosion. Furthermore, this paper discusses a suite of strategies designed to enhance the longevity of reinforced concrete structures. These include improving the concrete protective layer’s quality and bolstering the rebars’ corrosion resistance. As corrosion testing is essential for evaluating steel rebars’ resistance, this paper also details natural and accelerated corrosion testing methods applicable to rebars in concrete environments. Additionally, this paper deeply presents an exploration of the use of X-ray computed tomography (X-CT) technology for analyzing the corrosion byproducts and the interface characteristics of steel bars. Recognizing the close relationship between steel bar corrosion research and microstructural properties, this paper highlights the pivotal role of X-CT in advancing this field of study. In conclusion, this paper synthesizes the current state of knowledge and provides a prospective outlook on future research directions on the corrosion of steel rebars within reinforced concrete structures.

Lap-Shear Performance of Weld-Bonded Mg Alloy and Austenitic Stainless Steel in Three-Sheet Stack-Up

With the growing interest in utilizing Mg and austenitic stainless steel (ASS) in the automotive sector, joining them together in three-sheet configuration is inevitable. However, achieving this task presents considerable challenges due to the large differences in their physical, metallurgical and mechanical properties. To overcome these challenges, the feasibility of using weld-bonding to join Mg alloy/ASS/ASS was investigated. The nugget formation, interface characteristics, microstructure and mechanical properties of the joints were investigated. The results show that the connection between the Mg alloy and upper ASS was achieved through the combined effect of the cured adhesive and weld-brazing in the weld zone. On the other hand, a metallurgical bond was formed at the ASS/ASS interface. The Mg nugget microstructure exhibited fine columar grains composed predominantly of primary α-Mg grains along with a eutectic mixture of α-Mg and β-Mg17Al12. The nugget formed at the ASS/ASS interface consisted largely of columnar grains of austenite, with some equiaxed dendritic grains formed at the centerline of the joint. The weld-bonded joints exhibited an average peak load and energy absorption of about 8.5 kN and 17 J, respectively (the conventional RSW joints failed with minimal or no load application). The failure mode of the joints changed with increasing welding current from interfacial failure via the Mg nugget/upper ASS interface to partial interfacial failure (part of the Mg nugget was pulled out of the Mg sheet). Both failure modes were accompanied by cohesive failure in the adhesive zone.

Exploring potential of lead-free KSn0.5Ge0.5I3 based perovskite solar cell: A combined first-principle DFT and SCAPS-1D study

Perovskite solar cells present a promising alternative to conventional silicon or lead-based solar cells, offering a synergistic blend of cost-effectiveness and potential for elevated power conversion efficiency. We investigated the potential of an innovative KSn0.5Ge0.5I3-based perovskite solar cell (PSC) using density functional theory (DFT) and SCAPS-1D simulation studies. Computational analysis via DFT probed the crystal structure, elastic, mechanical, and optoelectronic properties of KSn0.5Ge0.5I3. Tolerance factor computation (0.94) and negative formation energy (-3.16 eV) affirmed the thermodynamic stability of the orthorhombic phase in KSn0.5Ge0.5I3. Optical variables including refractive index, absorption coefficient, dielectric function, optical loss, and reflectivity, were computed to explore KSn0.5Ge0.5I3 viability in PV applications. Band structure analysis, density of states (DOS), and projected density of states (PDOS) have been used to determine the band gap (∼1.87 eV), effective masses, and mobility of e-/h+. We have conducted SCAPS-1D simulation for diverse PSCs configurations using various holes transport layers (HTLs) and electron transport layers (ETLs), identified IGZO (Eg = 3.05 eV) as a proficient ETL while CuSbS2 (Eg = 1.58 eV) as an effective HTL. A comprehensive investigation of parameters such as absorber layer thickness, shunt and series resistance, donor and acceptor density, absorber defect density, back contact metal, temperature, and interface characteristics was undertaken, and the impact on PV device performances was assessed through current-voltage (IV) and quantum efficiency (Q.E) characteristics curves. These findings underscore the potential of KSn0.5Ge0.5I3 as a promising material for PSCs, offering a sustainable and eco-friendly avenue for future renewable energy.

Influence of the ribbed steel core on the inner interface mechanical behavior of the ESDCM pile

By virtue of the high strength, cost-efficiency and green construction, the expanded stiffened deep-cement-mixing (ESDCM) piles with steel cores own a great prospect to be applied for soft soil treatment in coastal and riverside regions. The dual-interface feature is a crucial factor affecting the bearing capacity of the ESDCM piles. However, the confining pressure characteristics of pile cores and the interface characteristics of steel pipe-soil-cement are unclear, limiting the practical application of ESDCM piles. Hence, in this work, we investigate the mechanical characteristics of the inner interface of ESDCM piles with steel cores via confining pressure transfer test and inner interface shear tests. The results demonstrate that the soil-cement column can withstand over 90 % of the confining pressure exerted on the outer interface, suggesting that the pile core may not be affected by confining pressure. Model piles with different steel cores have different interface failure modes, which can be described using either a three-segment or two-segment constitutive equation. Changing the inner interface structure has been proven to be a highly efficient pathway for enhancing the bearing capacity and adhesion conversion factor of the ESDCM pile. Compared with the smooth steel cores, the adhesion conversion factor can be reinforced up to 114.3 % by employing ribbed steel cores. Then, a model-pile bearing capacity calculation formula was established and verified for reliability. Moreover, the formula of a single pile based on inner interface shaft resistance was further proposed in combination with the actual operating conditions. This study highlights the mechanical characteristics of the inner interface of ESDCM piles, which guides engineering design and construction.

Pickering emulsions of zein nanoparticles co-stabilized by Tween 20: An effective strategy to stabilize citral in low pH environment

The demand for surfactant-free emulsions is growing significantly in food industry. Herein, we report the fabrication of zein nanoparticles, modified their surface hydrophobicity with Tween 20, and used them to stabilize various formulations of Pickering emulsions designated as ZT0 %, ZT5 %, ZT10 %, ZT15 %, ZT20 %, and ZT25 %, for preventing the acid-catalysed degradation of citral at 25 °C. Our results suggest that, as the concentration of Tween 20 increases, the droplet size of the emulsions first increases and then decreases, whereas the mechanical strength continuously increases. Citral encapsulated in ZT25 % shows maximum physicochemical stabilization as determined by visual, olfactory and HPLC analysis, and when released in saline shows maximum antioxidant activity due to the favorable charge characteristics on Pickering emulsifiers, and the existence of hydrophobic ⇋ electrostatic interaction. As compared to prior literature, our work represents a significant advancement in fabrication of zein nanoparticles (ZNPs), their stabilization using Tween 20 and the formation of appropriate Pickering emulsions stabilized by Tween 20 modified ZNPs appropriate for modifying the interfacial characteristics of the emulsion for enhanced physicochemical stability, excellent aroma profile, controlled release rate, and improved antioxidant activity of encapsulated citral under harsh acidic conditions. Moreover, the novel Chemical Kinetic Method has been applied to analyze and interpret the citral stability as a function of interfacial parameters. The study, therefore presents a novel particle-surfactant complex interface, having great potential for the encapsulation, protection, and release of citral from the acidic food/pharmaceutical formulations.

Warpage control and interface characteristics of Ti/Al composite plates by differential temperatures rolling with mobile induction heating

This study addresses the issue of warping and low interfacial bonding strength in composite plates due to uncoordinated deformation during the rolling of titanium/aluminum composites. By adopting mobile induction heating with differential temperature rolling composite technology, heated titanium plates and room-temperature aluminum plates were successfully rolled into composites. The results show that when the titanium plate is heated to 500–900°C, the warpage of the titanium/aluminum composite plates first decreases and then increases, while the interface shear strength first increases and then decreases. It is particularly emphasized that the rolled composite plates is straight at 800°C, the Ti6O oxide layer formed on the titanium plate surface exhibits excellent adhesion to the substrate, while displaying susceptibility to cracks during the rolling process, allowing fresh aluminum metal to be squeezed into the cracks to form a mechanical mesh and an atomic bonding diffusion layer occurs due to the fresh metal contact between titanium and aluminum within the crack, thereby resulting in the composite plates exhibiting optimal shear strength. The findings verify the preliminary feasibility of the proposed novel rolling process and provide a novel solution for prepared titanium/aluminum composite plates, which is an important step for future fabrication and applications of composite plates.

Sliding interface characteristics and self-lubrication mechanism of B4C-Al2O3 composite ceramics

B4C ceramics are an important structural material in the field of engineering. However, B4C ceramics have two fatal drawbacks: low fracture toughness and high friction coefficient. The design strategy and tribological mechanism of B4C ceramics with low friction are studied in this paper. The results show that the incorporation of Al2O3 as a second phase can not only increase the fracture toughness but also reduce the friction coefficient of B4C ceramics, achieving the self-lubrication of B4C ceramics. The low friction design strategy of B4C ceramics is realized by incorporating a second phase of Al2O3 to change the physical characteristic of the sliding surface. The sliding interface characteristic of in situ formed surface texture with an appropriate proportion of valleys in the sliding process is the most important factor for the improved tribological properties of B4C-Al2O3 composite ceramics. As the amount of Al2O3 incorporated is 30 wt%, B4C-Al2O3 composite ceramics have the most appropriate proportion of valleys in the surface texture, thus exhibiting the lowest friction coefficient. The clean phase boundary makes the bonding between B4C and Al2O3 grains firm, which is the key to achieving the function of the surface texture formed in situ. B4C-Al2O3 composite ceramics with both high fracture toughness and low friction coefficient will open a wider range of applications.

Study on the mechanism of freeze-thaw cycles on the shear strength of geogrid-sand interface

The geogrid-soil interface characteristic is a critical factor influencing the behavior of reinforced soil structures. In seasonal frozen regions, the shear strength of the geogrid-soil interface fluctuates periodically with temperature, necessitating consideration of freeze-thaw cycle effects during engineering design. In this study, a series of large-scale direct shear tests were conducted to investigate the geogrid-sand interface behavior under different freeze-thaw cycles. The mechanism of the evolution and variation of the geogrid-sand interaction was discussed based on test results and the associated mesoscopic analysis. The results indicate that freezing enhances the shear strength of the geogrid-sand interface, whereas freeze-thaw cycles reduce the geogrid-sand interface shear stress. The cohesion and friction angle of the geogrid-sand interface decreased as the number of freeze-thaw cycles increased, but tended to stabilize after several freeze-thaw cycles. The influence of freeze-thaw cycles on the tensile strength and elongation of the geogrid was insignificant. Internal changes in sand during freeze-thaw cycles were considered as the key issue that led to the deterioration of the geogrid-sand interface. Furthermore, considering the interface cohesion and normal stress, the influence of freeze-thaw cycles on the interaction coefficient k between geogrid and soil was analyzed, which is referable for the design and application of reinforced soil engineering in cold regions under similar conditions.

Modeling method and dynamic analysis of blade with double friction damping structure considering time-varying pressure distribution

A modeling and analytical method considering contact interface pressure characteristics is presented in this paper. Firstly, a high-fidelity model of a blade with a double friction damping structure is established by solid element, and a three-dimensional friction contact element is used to describe the nonlinear friction interface between the blade contact interfaces. Then, the static pressure distribution characteristics of the contact interface of the blade are obtained through the experimental device of the blade with double friction damping structure, and the accuracy of the pressure characteristics is verified. Based on the static pressure distribution, the time-varying dynamic pressure formula of blade contact interface is derived. The influence of the pressure distribution on the contact characteristics of the contact interface is analyzed and applied to the dynamic calculation of the rotating blade. The influence of different parameters on the blade dynamics is obtained. And the optimum mass ratio of the under-platform damper is obtained by simulating the operation condition of the aero engine blade acceleration process.

Influence of primary interface characteristics on mechanical properties and damage evolution of coal-rock combination

Indirect fracturing technology of coal seam roofs is a crucial method to enhance coalbed methane extraction efficiency in broken soft coal seams. The cracks formed significantly increase permeability by extending from the rock-coal interface into the coal seam. The structural features of the coal-rock interface are pivotal in determining the path of crack propagation, highlighting the importance of studying the mechanical properties and damage evolution in coal-rock combinations. Industrial CT, three-dimensional (3D) reconstruction, and 3D printing technology are utilized to create physical models with authentic interface structure features. Subsequently, coal-rock combination samples exhibiting smooth and original interface characteristics are produced through a layered pouring method. Uniaxial compression experiments are conducted on various interface feature combinations to examine the impact of primary interface structure characteristics on the mechanical properties and damage evolution of the combinations. Real-time monitoring is performed using acoustic emission (AE) equipment. The results show that the compressive strength of coal-rock combinations treated with glue and pouring is significantly higher than those treated with vaseline, while the axial strain shows an opposite trend. The presence of an interface constraint effect weakens the strength of the rock near the coal-rock interface, while enhancing the strength of the coal. The damage in coal-rock combinations initially occurs in the middle and lower parts of the coal, then progresses towards the interface and rock. Finally, a uniaxial compression model considering the interface constraint effect explains and theoretically demonstrates the phenomenon observed in the experiment, where more complex coal-rock interface structures result in higher compressive capacities of samples. It provides insights for further investigation into fracture trans-media expansion and permeability enhancement during the indirect fracturing of coal seam roofs.

Compression characteristics and fractography of in‐situ polymerisable thermoplastic and bio‐epoxy based non‐crimp carbon and glass fiber composites

AbstractThis experimental work involves characterization and fractography of a bio‐based epoxy and an in‐situ polymerisable thermoplastic polymer matrix based non‐crimp glass and carbon fiber composites under compressive loading. The laminates are characterized under compression loading using a combined loading compression (CLC) fixture. Laminates made using the thermoplastic matrix exhibit higher compressive strength (approx. 20% along fiber direction) compared to the bio‐epoxy based laminates. Further, both composites exhibit comparable compressive modulus characteristics. The tested composites are subjected to fractography analysis using Scanning Electron Microscopy (SEM) and Computed tomography (CT). SEM results indicate a difference in fiber‐matrix interface characteristics between the thermoplastic matrix and the bio‐epoxy matrix. Additionally, the CT scans reveal a difference in failure modes due to fiber orientations. A difference between failure mode of the exterior and interior plies of the specimens was also noticed. However, no specific influence of matrix type was observed on the overall macroscopic failure behavior.Highlights Bio‐epoxy and thermoplastic based laminates were characterized in compression. Post‐test fractography was performed using SEM and x‐ray CT scans. Use of thermoplastic matrix exhibits better fiber‐matrix adhesion compared to bio‐epoxy. Both laminates performed well in compression under laboratory test conditions.