Hole Wall Research Articles

Study on anti-reflection of deep soft and high gas coal seam floor by deep hole controlled blasting

Addressing the practical challenges of difficult drilling for blasting-induced permeability enhancement in deep, soft, and high-gas coal seams, where fractures remain underdeveloped and prone to re-compaction, this study proposes blasting operations within the floor strata. This approach aims to enhance the permeability of soft coal seams, thereby extending the duration of effective gas extraction. A bidirectional loading gas–solid coupling blasting simulation system was established in the laboratory, enabling multi-faceted analysis of experimental models through macroscopic crack patterns, internal damage mechanisms, and strain data of coal and rock masses. Comparative experiments were conducted, contrasting various control hole spacings with conventional blasting techniques. The findings reveal that as the blasting stress wave traverses the control hole walls, tensile stress waves are reflected, facilitating crack propagation. The guiding effect of the control holes and the spatial compensation they provide significantly increase the extension distance of explosion-induced cracks, resulting in directional failure of the test specimens and heightened damage in the far field of the blast. After the blasting process, the arrangement of control holes can result in an increase of up to 133% in damage to the coal seam and a reduction of up to 167% in damage to the floorboard compared to the model without control holes. Notably, when the control holes are proximal to the coal-rock interface, the near-end coal body experiences the most pronounced effects, with peak damage and tensile strain in the d = 20 mm model being 1.93 and 1.79 times higher, respectively, than those in models without control holes. Conversely, for control holes located further from the interface, the distal coal body experiences the greatest influence, exhibiting 1.53 and 1.55 times higher peak damage and tensile strain, respectively, in the d = 80 mm model compared to uncontrolled counterparts. Field observations at the C13 coal seam of a mine within the Huainan mining area corroborate these findings, where the volume of gas extraction and its concentration experienced a rapid increase following blasting and penetration enhancement. Optimum permeability enhancement occurs when the blasting hole is situated 4 m from the extraction point, resulting in a 131% increase in gas extraction purity from 0.15 × 10–3 m3/min to 1.97 × 10–3 m3/min. Furthermore, gas concentration soars by 373%, from 5.86% to 21.86%. These research outcomes offer valuable insights and hold considerable reference significance for blasting-induced permeability enhancement in deep, soft, and high gas coal seams.

Electrodeposition of Cu 3D structures suitable for CO2 reduction

Porous Cu foam electrodes, suitable for cathodic CO2 reduction, were deposited in an acidic sulphate solution with different additives to obtain structures with a high real surface area and an adequate mechanical stability. The influence of the electrodeposition time and solution composition on the porosity parameters, microstructure and stiffness of Cu 3D structures was evaluated. Neither ammonium acetate nor polyethylene glycol were found to be effective additives to the Cu sulphate electrolyte to achieve the main objectives. Only the presence of Cl– ions in the deposition solution resulted in a threefold increase in the real surface area and the achievement of a sufficient mechanical stability of the Cu 3D structure. The latter effect is related to the specific influence of Cl– ions during the electrodeposition process on the microstructural characteristics, such as the size of micropores in the walls of holes and crystallite aggregates that form dendritic branches. These structural changes, in contrast to the Cu samples deposited in a solution without additives, resulted in larger real surface areas, while the denser structures deposited in the presence of Cl– ions ensured the mechanical stability of the 3D structure.

АНАЛІЗ РОЗПОДІЛУ КОНТАКТНИХ НАПРУЖЕНЬ У ДВОЗРІЗНОМУ БОЛТОВОМУ З'ЄДНАННІ КОМПОЗИТНИХ ТА МЕТАЛЕВИХ ЕЛЕМЕНТІВ

Bolted joining technique is the dominant joining method for CFRP load-carrying structures in aircraft. However, the weak point of such structures are the areas located in the vicinity of the fastener holes, which are the areas of increased stress concentration. In addition, drilling the holes results in structural discontinuities due to cutting material fibers. Among all failure modes of composite bolted joint, bearing failure is one of the most common type of damage. This failure is caused by the local compressive stresses acting normal to the contact surface, that leads to delamination of material due to insufficient strength of matrix. Therefore, it is extremely important to optimize the design of composite bolted joints in order to enhance the entire composite structure. To increase the load-carrying capacity of the composite joint structural parts and protect the hole walls from damage, a method for installing titanium bushing with glue into the holes of composite plate is proposed. The paper presents the results of numerical analysis of the impact of stacking sequence on the distribution of contact stresses in a double-shear bolted joint of composite plate to steel cover plates. Using the finite element method and ANSYS Workbench 2019 R3 software, a three-dimensional finite element model of a double-shear bolted joint was created, which enables to analyze the impact of the stacking sequence on the distribution of contact stresses at the bolts to titanium bushings interface in the case of uniaxial tension of the middle composite plate at the level of tensile stresses in the gross section of 100 MPa. The obtained result explains the fundamental difference in the behavior of composite and metal materials: due to the change in the orientation and sequence stacking, the stiffness of the composite element of the joint changes, which affects the ovalization of the holes and the level of local deformations of the bushings, which in turn leads to a change in the maximum contact stresses and their concentration. By optimizing stacking sequence, it was possible to reduce the level of maximum contact stresses by 1.1 times. At the same time, the degree of unevenness of the distribution of contact stresses decreased by 1.21 times. The optimal stacking sequence was one in which 37.5% of the fibers oriented at an angle of 0°, 50% of the fibers oriented at angles of ±45°, and 12.5% of the fibers oriented at an angle of 90°

The analysis of damage mechanisms and vibration effects caused by cut blasting under various void shapes

The effect of the void shape on cut blasting is investigated by establishing a damage analysis model for a void using an improved calculation formula for stress on the wall of the void. Additionally, an optimization scheme is provided for the “square void cutting theoretical model.” The vibration effect of the rock mass outside the excavation area is simultaneously monitored, and its validity is substantiated through experimental and simulation-based verification. The findings indicate that the variation of q2sinθ over time aligns with the dynamic loading process of wall stress in holes. Under the influence of longitudinal waves, thin-walled circular damage occurs, and tensile effects from reflected waves are influenced by impedance. In a square void cutting model, two-stage stress waves cause tensile shear damage and inward collapse in the rock mass along hole walls. The explosive energy generated by square holes significantly contributes to fragmentation of rock masses. The circular empty-hole cutting model generates significant vibrations in central areas due to resistance. Vibration velocity in 45° direction for circular holes is lower than that for square voids outside cuts while vibration velocity remains equivalent between circular and square holes at 90° direction.

Impact of drilling parameters on the surface roughness of egg shell filled glass fibre/polyester composites

Abstract Glass fiber-reinforced polymers (GFRPs) are widely used in domestic applications such as doors, windows, and furniture, where drilling is a common machining process. The surface roughness of drilled hole walls is a critical factor, particularly in fastening applications, where smooth finishes are essential. This study explores the influence of drilling parameters on the surface roughness of GFRPs reinforced with different types of eggshell fillers viz.,un-carbonized, carbonized, and hybrid along with an unfilled variant. The research employs a Central Composite Design within the Response Surface Methodology (RSM) framework to investigate the effects of material type, spindle speed, feed rate, and point angle on surface roughness. Material type and point angle were treated as categorical variables, while spindle speed and feed rate were continuous, each with four levels, resulting in 16 experimental runs. The results showed that surface roughness values varied from 3.04 to 4.99μm, depending on the specific combination of drilling parameters. Statistical analysis using Analysis of Variance (ANOVA) confirmed that spindle speed and feed rate significantly impact surface roughness, with roughness increasing at higher speeds and feeds. Notably, the carbonized eggshell-filled GFRP variant achieved the lowest surface roughness. The study also developed a highly accurate regression model, validated through experimental data. The novel use of different variants of eggshell fillers in GFRPs provides a sustainable and effective way to enhance material properties. Further, conducting the drilling studies to observe the outcomes, offers potential industrial applications in the production of high-quality, durable composite materials.

Experimental study on shear mechanism of a new TU-type connector at HSS-UHPC interface

To maximize the benefits of high-strength steel (HSS) and ultra-high performance concrete (UHPC) composite structures, proper connections at HSS-UHPC interfaces are essential. Due to the significant variations in material strengths and component dimensions, traditional shear connectors could be unsuitable for HSS-UHPC interfaces. This study proposes a new TU-type connector (T-shaped rib with U-shaped holes), which has the advantages of high shear and tensile capacity, good slip capacity, low height limitation, and easy installation. Firstly, eighteen push-out tests of HSS TU-type connectors embedded in UHPC were performed to investigate the effect of connector heights and the contribution of connector flanges. The failure process, including the yielding of hole walls, the fracture of connector webs, and the development of fracture surfaces was discussed. Besides, the microstructures involving smooth areas, lamellar structures, and dimples on the fracture surfaces were presented by scanning electron microscope (SEM), and the effect of flange foam blocks on the out-of-plane displacements of UHPC slabs was investigated by digital image correlation (DIC). Secondly, the shear force–displacement curves and the load–strain relations of steel plates and rebars were discussed. In addition, the effects of considered parameters on shear capacity, peak slips, and shear stiffness were investigated. Finally, a strut-and-tie model was established to reveal the shear mechanism of TU-type connectors. Based on the principle of virtual work, the shear capacity equations of TU-type connectors were proposed.

Thickness and Structure of Permafrost in Oil and Gas Fields of the Yamal Peninsula: Evidence from Shallow Transient Electromagnetic (sTEM) Survey

The Yamal-Nenets Autonomous District, especially the Yamal Peninsula located in the permafrost zone, stores Russia’s largest oil and gas resources. However, development in the area is challenging because of its harsh climate and engineering–geological features. Drilling in oil and gas fields in permafrost faces problems that are fraught with serious accident risks: soil heaving leading to the collapse of wellheads and hole walls, deformation and breakage of casing strings, gas seeps or explosive emissions, etc. In this respect, knowledge of the permafrost’s structure is indispensable to ensure safe geological exploration and petroleum production in high-latitude regions. The extent and structure of permafrost in West Siberia, especially in its northern part (Yamal and Gydan Peninsulas), remain poorly studied. More insights into the permafrost’s structure have been obtained by a precise sTEM survey in the northern Yamal Peninsula. The sTEM soundings were performed in a large oil and gas field where permafrost is subject to natural and anthropogenic impacts, and its degradation, with freezing–thawing fluctuations and frost deformation, poses risks to exploration and development operations, as well as to production infrastructure. The results show that permafrost in the western part of the Yamal geocryological province is continuous laterally but encloses subriver and sublake unfrozen zones (taliks) and lenses of saline liquid material (cryopegs). The total thickness of perennially frozen rocks is 200 m. The rocks below 200 m have negative temperatures but are free from pore ice. Conductive features (<10 Ohm﮲m) traceable to the permafrost base may represent faults that act as pathways for water and gas fluids and, thus, can cause a geohazard in the oil and gas fields (explosion of frost mounds, gas blow during shallow drilling, etc.).

A comparative study for demonstrating the effect of the assist gas and E-field on hole generation characteristics induced by femtosecond laser layered ring hole-cutting of magnesium alloy AZ91D sheets

The widely-used magnesium alloy AZ91D is light-weight and energy-saving with good castability and mechanical performance. The traditional machining way for magnesium and its alloys is the high-speed mechanical contact cutting, which usually leads to uncontrollable intense ignition with some notable heat-induced machining defects. However, it has been rarely reported that the non-contact precision laser machining is used for cutting the magnesium and its alloys. The problems such as the local heat effect, the heat-induced defects and the local ignition as well as the vapor-plasma plume usually encountered during laser machining of magnesium and its alloys. Hence, in this study, a hybrid laser cutting way of femtosecond laser layered ring hole-cutting using the assist gas and E-field is reported to machine micro holes in the AZ91D material. The effect of the lateral E-field and assist gas on the hole formation characteristics was demonstrated for femtosecond laser cutting of the AZ91D sheets. It was indicated that the use of the lateral E-field and assist gas suppressed the ignition as well as the vapor-plasma plume. The hole depth was increased by the external assistance used especially the lateral nitrogen blowing. The hole wall formation quality was improved by using the lateral E-field and compressed air blowing, while it got poorer if using the lateral nitrogen blowing. The ignition-induced carbonization was effectively suppressed by the assist gas used. The hole depth, microstructure and micro hardness were improved by using the lateral E-field and assist gas.

Flexural behavior and design of aluminum alloy portal frame eaves joints

Aluminum alloy portal frames (AAPFs) are suitable for both long-term and temporary buildings owing to their light weight, ease of installation and disassembly, and excellent corrosion resistance. Due to the critical importance of joint mechanical behavior for structural safety, this paper conducted experimental and numerical studies on the flexural behavior of AAPF eaves joints. Initially, bending tests on four AAPF eaves joints revealed three failure patterns: connection plate, column, and hole wall failure. The failure patterns are determined by the weakest of these three components. Adding haunches increased the bending zone area, thereby increasing the ultimate bearing capacity by 110 % compared to joints without haunches. Furthermore, strain curves indicated that the load transfer zone was subjected to a bending-shear force state, consistent with the principle that the bolt group shear forms a force couple to transfer the moment. Subsequently, a finite element (FE) model was developed and validated to provide a foundation for subsequent parametric studies and theoretical analysis. The parametric analysis considers bolt diameter, connection plate thickness, aluminum alloy web thickness, and bolt end distance. The bearing capacity corresponding to three failure patterns was discussed, and a design method for the flexural bearing capacity was proposed. The design method for stiffness model was also proposed based on the component-method and parametric analysis. Finally, this paper presented and validated the design steps for the flexural behavior of the eaves joints throughout the whole process, providing an important reference for engineering design.

Modeling and verification of cortical bone drilling forces based on tissue structure heterogeneity

Bone drilling mechanism study is the basis for the optimization of cortical bone drilling process and drill geometry. In this paper, a drilling force model for modified drills with thinned chisel edge is established considering the heterogeneous structure of cortical bone. The bone mineral density is embedded into the established model, the model can predict the axial thrust force change along the drilling depth direction, and the model is verified through cortical bone drilling experiments. The thrust force and torque predicted by the model are in good agreement with the drilling experimental results of cortical bone drilling. Then, the drilling performance of the modified drill and the common drill is compared through cortical bone drilling experiments. Compared with common drill bits, the maximum reduction in average thrust force of the modified drill bit during stable drilling is 21.21 % (n = 2500 rpm, Vf=60 mm/min). The maximum reduction in average roughness of the hole wall is 21.87 % (n = 500 rpm, Vf=10 mm/min). The drill chisel edge thinning design reduces the negative impact of the negative normal rake angle on the cutting lip of common drill on drilling force and stability. Therefore, the drill bit chisel edge thinning design can effectively improve the drilling performance.

An experimental and theoretical investigation on residual stress of 7075-T651 aluminum alloy hole under electromagnetic cold expansion

The electromagnetic cold expansion process (ECE) was adopted in this work. The theoretical plastic radius, hole wall stress, radial stress, circumferential stress and release stress under different expansion rates (ER) were studied based on thick cylinder theory and ECE experiments. The released strain, residual stress (RS) and failure force were measured. The tensile fracture morphology was characterized. The results showed that the theoretical plastic radius (maximum 15.87 mm), internal stress (maximum 982.9 MPa), radial stress (maximum −820.9 MPa) and circumferential stress (maximum −271.4 MPa) increased with the increase of ER. The absolute radial and circumferential stress decreased and increased in negative and positive ranges respectively with distance increased. The release strain (maximum −3033 με, 10−6 microstrain), radial RS (maximum 600.9 MPa) and circumferential RS (maximum 601.1 MPa) also increased with the increase of ER, and the minimum relative error of the plastic zone radius of the theoretical model was 3.78 % proving the reliability of the model. In addition, ECE increased the release stress (the maximum radial and circumferential release stresses were 1402.6 MPa and 747.5 MPa) and decreased the failure force (minimum 44.7kN) with increased ER. The initial crack position tended to transition from the inlet and outlet surfaces to the middle position, and the crack propagation angle and axial crack size gradually decreased with the decreased ER and stress level.

Influence of fibers and bubble structure on thermal conductivity and mechanical performances of foam concrete

This study aims to effects of fibers and bubble structure on thermal conductivity and mechanical performances of foam concrete. The factors of fiber type, length, fiber dosage, and silica fume dosage were considered. The workability and compressive strength tests were carried out. The bubble structure was observed. Numerical simulation of thermal conductivity was performed. The results indicated that the influence of a single factor on the strength of foam concrete is slight. The addition of silica fume significantly reduces the workability of foam concrete. The synergistic effect of silica fume and PP fiber can improve the compressive strength of foam concrete. The compressive strength of foam concrete with good performance is 7.2 MPa, and the dry density is 827 kg/m3. The pore diameter of about 400 μm is the main pore diameter that affects the strength of foam concrete. The thermal conductivity of foam concrete with the same porosity but different pore size distribution is similar when the pores are closed. The defects on the hole wall, small aperture and uniform distribution are still conducive to improving the strength. When the profile of the same temperature passes through the pore, the curve is concave and convex first, and the larger the pore size, the more obvious this phenomenon is. The holes in the foam concrete play a role in dissipating energy during heat transfer.

Study on the influence of cortical bone heterogeneity on the spatio-temporal distribution of drilling temperature

The degree of thermal damage during cortical bone drilling is an important factor in determining the success rate of surgery and postoperative recovery time. In this study, high and low feed rate drilling experiments are carried out on bovine femoral cortical bone by chisel edge thinning drill. Combined with the characterization of cortical bone tissue structure and the measurement results of important thermal property parameters, the potential impact mechanisms of cortical bone heterogeneity on the spatio-temporal distribution of drilling temperature and thermal damage are analyzed. The temperature rise rate and overheating duration at different distances from the hole wall in cortical bone drilling under different feed rates are also compared. The experimental results show that the specific heat gradually increases and the thermal conductivity gradually decreases from the periosteum to the endosteum. The hole wall temperature and thermal diffusion of cortical bone with different tissue structures are different under high and low feed rates. The closer to the cortical bone endosteum, the lower the drilling temperature, thermal diffusion and thermal damage area. This is not only related to the contact time between the drill bit and the hole wall of cortical bone with different tissue structures, but also closely related to the heterogeneous structure of cortical bone. In addition, it is found that in high feed rate cortical bone drilling, the temperature rise rate at different positions from the hole wall is higher and the overheating duration is shorter.

Improving breaking efficiency of hard rock: Research on the mechanism of impact-shear rock breaking technology

To expedite drilling operations in hard rock of coal mines, a new type of impact-shear drill bit was developed, and its mechanism of speed-up and efficiency increase was studied. The RHT constitutive model was used to describe the structural behavior of rock, and the rock-breaking simulation model of full-size bit was established. Compared with PDC bit and hammer bit, the rock-breaking force, bit torque, and rock stress characteristics of impact-shear bit were analyzed. The results show that, in comparison to PDC bit and hammer bit, the axial force of impact-shear bit was reduced by 68.25% and 71.40%, respectively, and the average torque was reduced by 91.79% and 83.36%, respectively. Notably, for the impact-shear bit, the fluctuation of drilling force was effectively mitigated, the stick–slip vibration of bit was weakened, the rock-breaking energy consumption was drastically reduced, and the rock-breaking efficiency and bit’s life were finally improved. In terms of rock stress characteristics, the pre-impact effect of the central hammer bit of the impact-shear bit can release the internal stress of the rock well, and the stress of the rock element on the hole wall was relatively reduced, thus making it easier for the external PDC bit to break the rock. Field test results show that, under the condition of the small drilling rig, the impact-shear bit can give full play to the pre-crushing function of the impact mechanism, thereby effectively protecting the PDC cutter of external PDC bit, and realizing the fast hole-forming in hard rock of coal mine.

Effect of stress conditions on concentrated leak erosion resistant of fine-grained soils with different characteristics

AbstractInternal erosion is one of the most important factors that cause earth structures that retain water, such as embankment dams, to collapse. Concentrated leak erosion, one of the forms of internal erosion, occurs in cracked fine-grained soils and pressurized flow conditions. To evaluate the concentrated leak erosion risk of cracks/voids, it is necessary to ascertain the erosion resistance of these materials. The erosion rate and critical shear stresses determine internal erosion resistance in concentrated leak erosion. This study determined soil’s concentrated leak erosion resistance using test equipment that allowed the flow to pass through a hole with stress-free (no loading), anisotropic-compression stress, anisotropic-expansion stress, and isotropic stress conditions. The stresses that developed in the samples’ hole wall where erosion occurred were determined with numerical modeling as pre-experimental stress conditions. The experiments were performed under a single hydraulic head on four selected cohesive soils with different erosion sensitivity. Time-dependent flow rates obtained from the test system can be used to determine hydraulic parameters, such as energy grade lines, with the help of basic theorems of pipe hydraulics in theoretical hydraulic models. Moreover, the erosion rates were quantitatively determined using the continuity equation, while critical shear stresses were qualitatively compared for concentrated leak erosion developed by the dispersion mechanism. As a result of the experiments, stress conditions influence the concentrated leak erosion resistance in the soil samples with dispersive erosion. Moreover, the shear strength in the Mohr–Coulomb hypothesis can explain the erosion resistance in these soils under stress conditions depending on the sand/clay ratio.

Hydraulic fracture characterization of debris-rich ice hole for polar geological drilling based on Peridynamics

Polar geological drilling is crucial to investigating the earth's environment and climate evolution. Hydraulic fracturing occurs around the ice holes when drilling into the complex debris-rich ice before entering the bedrock. Based on the nonlocal theory, the ice-debris structure is considered in the stability of the borehole wall, and a peridynamics model is developed to explore fracture initiation and propagation characteristics around the debris-rich ice hole. The integrated equation describes the mechanical behavior of ice holes, and the continuous and discontinuous spaces are described uniformly around debris-rich ice holes, avoiding the singularity of local continuum mechanics at the interface and crack tip. In this paper, the separation behavior of the interface is simulated between ice and debris. The cracking propagation process, the influence of debris size and shape, and horizontal pressure are analyzed. The results show that at a hydraulic pressure of 4.0 MPa, 8 radial cracks are initiated from the wall of the ice hole containing circular and elliptical debris, with the final crack volume of 0.66% and 1.40%, respectively. The cracks near the hole wall propagate a circumferential direction after turning or branching, leading to peeling in the ice hole containing elliptical debris with inclination angles of 30° and 60°. Hydraulic pressure balances stress distribution around debris-rich holes when horizontal pressure ranges from 1.2 to 2.4 MPa. When drilling into debris-rich ice formations at different debris and horizontal pressures, it is imperative to adjust promptly the density of drilling fluid. This adjustment aims to regulate the hydraulic pressure within the hole, minimize crack distribution, and ensure safe access to bedrock for coring.

Study on hole wall morphology and defects in burst mode of femtosecond laser drilling

Through-hole drilling experiments are conducted on nickel-based superalloys GH3536 using femtosecond laser and burst modes of femtosecond laser. The morphology and roughness of the hole wall are studied. Indentation experiments show an increase in microhardness to 10 GPa in the recast layer at the edges of holes at GHz mode and MHz-200 μJ. EDS finds that the increase is attributed to oxidation and the formation of Cr2O3. EBSD and kernel average misorientation (KAM) reveal the laser induced heat-affected-zone (HAZ) at Single-Pulse-200 μJ and GHz-200 μJ. The removal characteristics under four burst modes are compared in single pulse/burst percussion experiment, indicating that the efficient removal of molten material in BiBurst mode accounts for its superior hole wall quality. The BiBurst mode offers significant advantages in terms of enhancing machining efficiency while minimizing material damage, which can extend to various metal materials.

Investigation on effect of cryogenic cooling on the hole-making of CFRP with conventional PCD tool and textured PCD tool

Carbon fiber reinforced polymer (CFRP) has obtained the widespread use in significant basic parts owing to its excellent properties. Different methods including the conventional PCD tool using dry machining (CPD), the conventional PCD tool with CO2 cryogenic cooling (CPC), and the textured PCD tool with CO2 cryogenic cooling (TPC), were introduced to investigated their effects on the holes-making performance. Results demonstrated that the obtained average entrance diameter and relative error of different spindle speeds using the CPC were about 4001 to 4005.4 μm and 0.025% to 0.65%, respectively. Dimensional accuracy and surface edge quality of entrance hole can be better improved by the CPC method. It was found that the cryogenic cooling method showed the remarkable effect in improving the anti-adhesion of tools than compared to the dry machining. Additionally, results indicated that the cryogenic cooling resulted in the significant fiber fractures and many pits inside the hole wall and the CPD method can help to improve the inner hole wall quality.

Real-time dynamic damage monitoring of ultra-thin-ply composite bonded/bolted joint interference-fit installation based on evolutionary affinity propagation

This research introduced ultra-thin prepregs for designing equal-thickness laminates and conducted experimental tests on interference-fit. The uncertainty of damage, attributed to the bearing and friction exerted by the shank against the hole wall during installation, posed a significant challenge. Moreover, the absence of real-time damage monitoring methods in existing literature. In this paper, we proposed the utilization of acoustic emission (AE) technology in conjunction with the evolutionary affinity propagation (EAP) algorithm to facilitate dynamic, real-time monitoring and classification of damage. The findings indicated that employing ultra-thin in composite interference-fit installations substantially reduced damage to the hole walls. Furthermore, the EAP algorithm surpassed traditional methods in its ability to accurately and efficiently monitor and analyze damage dynamically throughout the interference-fit installation.

Investigation of ultrasonic-assisted drilling temperature of SiCp/Al composites

ABSTRACT Due to their excellent properties and low manufacturing costs, SiC particle-reinforced Al matrix composites (SiCp/Al) find extensive application in automobile manufacturing and aerospace. However, SiCp/Al is less machinable. The ultrasonic-assisted drilling (UAD) decreases tool wear and enhances the quality of drilled holes when compared to conventional machining techniques. This paper investigates the effect of drilling temperature variations induced by processing conditions on the degree of softening of the base material during UAD of SiCp/Al. It also analyses the mechanism of how drilling temperature affects the quality of the holes made from the perspective of matrix softening. The study demonstrates a regularity in the impact of spindle speed, ultrasonic supply voltage(ultrasonic vibration amplitude), and feed rate as a function of drilling temperature. The effects of temperature changes caused by each of these factors on import/export edge defects, surface scratches on the hole wall, and tool machinability vary.