Formation Mechanism Of Morphology Research Articles

Research on the material removal mechanism of vibration-assisted nano-scratch on single-crystal GaN by molecular dynamics.

Single-crystal gallium nitride (GaN) is a semiconductor material known for its hardness and brittleness. This research aims to reveal the differences in the micro-mechanisms of material removal during traditional grinding and ultrasonic vibration-assisted grinding and to provide guidance for the high-efficiency, high-quality planarization processing of single-crystal GaN. To achieve this purpose, molecular dynamics (MD) simulation methods were used to establish a model (30nm × 40nm × 15nm) of single-crystal GaN being scratched by a single abrasive grain with and without ultrasonic vibration assistance. The differences in the surface morphology and subsurface damage formation mechanisms of single-crystal GaN under conditions with and without ultrasonic assistance were compared. The results indicate that, compared to traditional grinding, the periodic ultrasonic vibrations reduce the normal force and result in a more uniform distribution of stress and temperature, thereby mitigating local stress concentration and thermal accumulation effects. Ultrasonic vibration alters the motion of the abrasive grain, expanding the material removal range from 7.384 to 10.315nm, decreasing the number of residual atoms in the machining area, and lowering the chip pileup height at the leading edge of the abrasive grain from 2.063 to 1.528nm. Additionally, the micro-shear deformation induced by ultrasonic vibrations helps to suppress brittle fracturing caused by excessive local stress, thus reducing the thickness of the damaged subsurface. At a scratch depth of 2nm, the total length of dislocation lines in the ultrasonic-assisted scratch is reduced from 185.256 to 33.315 nm compared to traditional scratching. These findings offer new insights into the microscopic mechanisms of material removal in high-efficiency, high-quality grinding processes of single-crystal GaN. This study adopts LAMMPS software for MD simulations to investigate the physical behavior of GaN during the grinding process. The simulation results are then visualized and analyzed using OVITO software to elucidate microstructural changes in the material. During the simulation, the temperature of the Newtonian layer is calculated based on the statistical analysis of atomic velocities under the NVE ensemble. The grinding force applied to the GaN workpiece is determined by differentiating the atomic potential energy. Von Mises stress analysis is adopted to ascertain the stress distribution during the scratching process. Finally, the changes in the crystal structure during scratching are identified and classified using analysis of identified defect structures.

Study on the morphological characteristics of thermally modified bamboo milling dust

Abstract The hazards of dust are receiving increasing attention with the application of bamboo industrialization. This study focuses on the morphological characteristics and formation mechanisms of milling dust from raw bamboo, dried bamboo, and thermally modified bamboo treated at varying temperatures. The particle size distribution, area-equivalent diameter, minimum Feret diameter, aspect ratio, roundness, and convexity were investigated. A new method combining sieving and image scanning analysis was applied to identify the size and morphology of the dust. The study has found that thermal modification significantly affects particle size and distribution, impacting dust convexity and surface characteristics. Particle size has a greater impact on dust morphology compared to heat treatment temperature. Thermal treatment is shown to degrade hemicellulose, reducing bamboo’s transverse mechanical properties and thereby altering the generated dust. The three-step cutting process is established, including bamboo milling deformation and dust formation by finite element simulation. This study offers a reference for optimizing dust removal ports and enabling real-time adjustments to dust removal system power based on dust morphology.

Stray current affected zone in electrochemical jet machining

The stray current affected zone (SCAZ) in electrochemical jet machining (EJM) poses a significant and often unavoidable challenge. This study offers an in-depth analysis of the morphological characteristics and formation mechanisms of SCAZ in EJM through a combination of machining experiments and surface characterization. By investigating various workpiece materials and electrolytes, we identify that stray corrosion phenomena are highly dependent on the specific material-electrolyte combinations used. Although applying ultra-short pulses of 750 ns enhances shape accuracy, it does not fully prevent pitting corrosion. Conversely, the bipolar pulse technique effectively reduces pitting, though stray oxidation remains an issue. As a result, post-finishing processes are crucial. Notably, plasma electrolytic polishing is demonstrated to be highly effective in removing stray oxidation, achieving a glossy surface on SUS304 in just 3 s while maintaining dimensional accuracy.

Deep Learning-Driven Prediction of Mechanical Properties of 316L Stainless Steel Metallographic by Laser Powder Bed Fusion.

This study developed a new metallography-property relationship neural network (MPR-Net) to predict the relationship between the microstructure and mechanical properties of 316L stainless steel built by laser powder bed fusion (LPBF). The accuracy R2 of MPR-Net was 0.96 and 0.91 for tensile strength and Vickers hardness predictions, respectively, based on optical metallurgy images. Feature visualisation methods, such as gradient-weighted class activation mapping (Grad-CAM) and clustering, were employed to interpret the abstract features within the MPR-Net, providing insights into the molten pool morphology and grain formation mechanisms during the LPBF process. Experimental results showed that the optimal process parameters-190 W laser power and 700 mm/s scanning speed-yielded a maximum tensile strength of 762.83 MPa and a Vickers hardness of 253.07 HV0.2 with nearly full densification (99.97%). The study marks the first application of a convolutional neural network (MPR-Net) to predict the mechanical properties of 316L stainless steel samples manufactured through laser powder bed fusion (LPBF) based on metallography. It innovatively employs techniques such as gradient-weighted class activation mapping (Grad-CAM), spatial coherence testing, and clustering to provide deeper insights into the workings of the machine learning model, enhancing the interpretability of complex neural network decisions in material science.

Subnanoscale Ion Beam Modification-Assisted Smoothing of Heterostructure Surfaces.

Glass ceramic (GC) is the most promising material for objective lenses for extreme ultraviolet lithography that must meet the subnanometer precision, which is characterized by low values of high spatial frequency surface roughness (HSFR). However, the HSFR of GC is typically degraded during ion beam figuring (IBF). Herein, a developed method for constructing molecular dynamics (MD) models of GC was presented, and the formation mechanisms of surface morphologies were investigated. The results indicated that the generation of the dot-like microstructure was the result of the difference in the erosion rate caused by the difference in the intrinsic properties between ceramic phases (CPs) and glass phases (GPs). Further, the difference in the microstructure of the IBF surface under different beam angles was mainly caused by the difference in the two types of sputtering. Quantum mechanical calculations showed that the presence of interstitial atoms would result in electron rearrangement and that the electron localization can lead to a reduction in CP stability. To obtain a homogeneous surface, the effects of beam parameters on the heterogeneous surface were systematically investigated based on the proposed MD model. Then, a novel ion beam modification (IBM) method was proposed and demonstrated by TEM and GIXRD. The range of ion beam smoothing parameters that could effectively converge the HSFR of the modified surface was determined through numerous experiments. Using the optimized beam parameters, an ultrathin homogeneous modified surface within 3 nm was obtained. The HSFR of GC smoothed by ion beam modification-assisted smoothing (IBMS) dropped from 0.348 to 0.090 nm, a 74% reduction. These research results offer a deeper understanding of the morphology formation mechanisms of the GC surfaces involved in ion beam processing and may point to a new approach for achieving ultrasmooth heterostructure surfaces down to the subnanometer scale.

Pulsed galvanostatic electrodeposition of tellurium nanostructures on stainless steel from copper anode slimes plating bath: Effect of pulse parameters

The electrochemical behavior of Te in alkaline media was determined by cyclic voltammetry and linear sweep voltammetry measurements. It indicated that TeO32− ion was first reduced to Te(s), then to Te22− ion. For the first time, the pulsed electrodeposition of tellurium on stainless steel has been studied in an alkaline bath and the effect of duty cycle, frequency, and current density on current efficiencies and morphology were indicated at room temperature. Pulse duty cycles ranging from 10 to 75%, frequencies ranging from 10 to 100 Hz, and current densities ranging from 7.5 to 30 mA/cm2 were employed. The morphology of the electrodeposition of tellurium samples was characterized by SEM. The results showed that due to increasing side reactions at higher current density, the current efficiency decreased with increasing current density. The results of Scanning Electron Microscopy (SEM) cleared that more compact structures with lower porosity were observed for the electrodeposits at lower current densities and less compact samples were obtained at higher current densities. It has been found that the current efficiency of tellurium plating decreases as the pulse duty cycle increases from 10% to 75%. Maximum current efficiency has been observed at 10% duty cycle. The study of the effect of duty cycle on morphology showed that the samples synthesized at a duty cycle of 10% and 25% have approximately similar appearance and particle size. With more increasing of duty cycles to 50 and 75% due to increasing hydrogen evolution rate and H2 bubbling at the electrode surface the morphology has been changed remarkably. The current efficiency of the deposit tellurium exhibited a strong dependence on the frequency. As frequency increases, the current efficiency almost decreases. In most cases, the maximum current efficiency is obtained at a 10 Hz frequency. The study of the effect of frequency on morphology showed that hydrogen evolution plays a significant role in the morphology formation of samples obtained at low pulse frequency (10 Hz), two processes of hydrogen evolution and anisotropic growth have key roles in morphology formation at medium pulse frequency (50 Hz) and anisotropic growth is the mechanism of morphology formation at high pulse frequency (100 Hz).

Preparation of CuBTC@PET Hierarchically Porous Composite Membranes via In Situ Growth Method and Their Antibacterial Filtration Performance

Processing polyethylene terephthalate (PET) into functional materials has both sustainable and economic significance. Therefore, this study aims to prepare functional nanofibers using PET, combining electrospun nanofibers with metal–organic frameworks (MOFs), which is an effective solution to increase the added value of functional nanofiltration membranes (NFMs). The surface morphology of PET fibers is successfully controlled by electrospinning parameters and post-treatment. The formation of a uniform coating of CuBTC crystals on the PET surface is induced by a simple and low-cost in situ growth technique. CuBTC@PET was treated to prepare superhydrophobic CuBTC@PET (SCP), thus improving the stability of CuBTC in water and expanding its potential applications. Through a series of optical and thermal characterizations, the porous morphology formation mechanism and MOF in situ growth mechanism of SCP fibers were discussed. Then, the air filtration performance and bacteriostatic properties of SCP nanofiltration membranes were investigated. The as-prepared SCP showed a high water contact angle (146.4°), low-pressure drop (39.7 Pa), and high filtration efficiency (95.3%, 3 μm NaCl), as well as unique, broad-spectrum antibiosis potency against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). This study shows that SCP nanofiltration membranes can be practically applied in high-performance antibacterial filtration membranes.

Analysis of mechanisms of bubble characteristics and molten pool dynamics in EDM based on a three-phase flow model

Bubble characteristics and bubble volume fraction have significant effects on crater morphology and machining efficiency during electrical discharge machining (EDM) in liquid. Therefore, there is a need to elucidate the mechanism of bubble characteristics in EDM and analyze the mechanism of crater formation based on these bubble characteristics. However, since EDM is a transient multiphysics process, it is extremely difficult to understand bubble characteristics using experimental methods. Therefore, the generation, expansion, explosion, and disappearance of bubbles during EDM were simulated based on a three-phase flow model in this study. The model used the phase field method to track the boundary motion, judged the existence mode of each phase according to the order parameter gradient function, and analyzed the formation of crater morphology by the gradient of surface tension in the molten pool. The motion process of bubbles, the material removal mode, and the formation mechanism of crater morphology during the pulsed discharge were analyzed using the model. The results revealed that the periodic motion of the plasma channel would drive the molten pool to produce the corresponding periodic motion, and the bubbles would grow following the periodic motion of the molten pool. The material was removed in different ways in different periods, among which the removal mode of molten splash was predominant. The surface tension gradient inside the molten pool, the periodic motion of the molten pool, and the hydrostatic pressure in the molten region had a combined effect on bubble motion, the flow of the molten pool, and the formation of the crater morphology.

Controllable fabrication of well-shaped PMBA@CsPbBr3 nanoparticles for highly sensitive detection of HCl and HBr.

We report a facile two-step strategy to construct well-shaped PMBA@CsPbBr3 nanoparticles, with this strategy involving combining in situ adsorption and controlled polymerization. The morphological evolution process and mechanism of formation of the nanoparticles were demonstrated, and the nanoparticles showed high sensitivity to corrosive acid gas. This work has provided an effective approach for fabricating well-structured perovskite-based nanocomposites.

Scratch-induced surface formation mechanism in C/SiC composites

Due to the extremely complex composition of C/SiC composites, their material removal mechanisms are significantly different from those of conventional single-phase ceramic materials. Therefore, the grinding removal mechanism of C/SiC composites must be investigated so that the components based on these composites can be machined efficiently and with low damage. In this paper, nano-scratch experiments with various cutting depths are carried out along different fiber orientations to simulate the material removal process in grinding and theoretically clarify the damage failure mechanism based on different cutting thicknesses. According to the assessment of surface and subsurface morphology of the various constituents in the scratch grooves regarding different fiber orientations, the multiple brittle breakage modes and surface integrity of carbon fiber are revealed. Green’s function is applied to establish a half-space anisotropic analytic elastic stress field considering the microstructural characteristics of material, and the crack nucleation and propagation principles during micro brittle fracture regime for nano-scratch experiment are elucidated based on the fracture mechanics and the maximum principal stress criterion. The formation mechanism of machined surface morphology in macro brittle removal process is investigated under the crack deflection effect at the weak interface and based on the elastic foundation beam theory. The related findings can provide a reasonable reference framework for optimizing the grinding technology, material and tool design regarding C/SiC composites.

The morphology features, formation mechanism and elimination of channel segregation in industrial-scale Ti–Nb ingots produced by vacuum arc remelting

In this study, the morphology characteristics and formation mechanism of channel segregation in the industrial-sized Ti–Nb binary ingots produced by vacuum arc remelting (VAR) are researched based on experiments and calculations. The results show that the channel segregation is usually located at the 1/4–3/4 radius of the ingot and the morphology is closely related to the VAR process. The Ti-enriched channel segregation stripes tend to parallel to the ingot centerline and columnar dendrites in steady-state remelting region and hot-top region, respectively, while along the molten pool profile in residual molten pool region. For the first time, the Ti2O3 particles precipitated in the channel segregation were observed, following the orientation relationship of <001>β//<133>Ti2O3 and {11‾0}β//{011‾}Ti2O3 with β matrix in coherent boundary. First-principles calculations evident that the enrichment of Ti-solute tends to decrease the formation enthalpy, and hence makes for the precipitation of Ti2O3 particles. The numerical simulation and the experiment results manifest that the channel segregation originates from the convergence of interdendritic Ti-enriched liquid, resulting in the density inversion between the Ti-enriched initiation site and the surrounding liquid. The density gradient and the solidification rate dominate the growth direction and the radius distribution of the channel segregation. Based on the above, an optimized technique with helium cooling and the external stirring magnetic field was conducted and the channel segregation was eliminated successfully.

Numerical study failure characteristics of natural fracture under induced stress

Hydraulic fracturing is an effective method for developing oil and gas in unconventional reservoirs. The openings of natural fractures directly affect the complexity of the fracture body. The failure characteristics of natural fractures are critical factors in determining their activation by hydraulic fractures. Based on the three-dimensional displacement discontinuity method, a three-dimensional mechanical model of the interaction between hydraulic and natural fractures was established. Based on the shear and tensile failure criteria of the natural fractures, the failure characteristics of different natural fractures were clarified. Research has shown that the failure characteristics of natural fractures are influenced by factors such as three-dimensional stress, spatial distribution, and roughness. After the hydraulic fractures pass through the natural fractures, tensile and shear failures occur simultaneously; the failure of natural fractures is primarily affected by their strike and dip angles. During the process of hydraulic fracture approximation, the shear stress increases as the distance between the hydraulic fracture tip and natural fracture decreases. When the strike angle of the natural fractures near the tips of the hydraulic fractures was greater than 35°, the stress became consistent. As the dip angle of the natural fractures increased, the lowest point of the shear stress gradually moved from the upper to the lower half. This research studies the tensile and shear failure of natural fractures under different conditions, in order to facilitate engineering judgment of the types and characteristics of natural fracture failure. It is of great significance for us to understand the formation mechanism of complex fracture network morphology in volume fracturing.

A novel micro-rolling & incremental sheet forming hybrid process: Deformation behavior and microstructure evolution

Thin-walled metal parts with functional micro-featured surface have broad application prospects in the fields of resistance reduction, noise reduction, etc. In this study, a novel micro-rolling & incremental sheet forming hybrid process (μR-ISF) is proposed to fabricate thin-walled metal parts with microgroove arrays. An analytical model which relates the rolling force and microgroove depth in the micro-rolling stage was first established. Then, the formation mechanism of microgroove morphology during both micro-rolling stage and macro-shape forming stage are investigated. After the micro-grooved sheet being incrementally formed, a significant reduction (between 21% to nearly 60%) is occurred in the depth of both transverse and longitudinal grooves compared to the flat sheet. Meanwhile, the width of transverse grooves decreases slightly by about 10% on average, while the width of longitudinal microgrooves increases significantly by more than 30% on average. After micro-rolling, 85°{101¯2} tensile twins appear on the micro-grooved sheet and the percentage of 65°{112¯2} compressive twins increases. After incremental forming, the percentage of low-angle grain boundaries and the density of geometrically necessary dislocations in the formed part increase significantly, and the grain size distribution becomes more uniform. The present work provides a new strategy for the fabrication of 3D metal thin-walled components with surface micro-features.

Study on the surface morphology formation mechanism of femtosecond laser processing gold

ObjectiveTo find out the surface morphology formation mechanism when using femtosecond laser to drill holes on gold film. Materials & methodsWe used femtosecond laser with 800 nm wavelength and 1 kHz maximum frequency, gold film with a thickness of 200 μm on copper substrate to carry out the research. Based on two-temperature model, we studied the heat transferring and surface morphology formation mechanism of femtosecond laser processing gold with numerical simulation method. In experiment research, we used femtosecond laser to drill holes on gold film, the parameters of laser are the same as those of the simulation, then we used the AFM (Atomic Force Microscope) to observe and measure samples. ResultsWe calculated the ablation threshold of 800 nm femtosecond laser on gold material according to the results of simulation, the value is 0.19 J/cm2. Considering micro forces on melted materials, we also got some micro surface morphologies’ pictures with the method of numerical simulation. We found some raisings around the edges of holes drilled by laser on gold, and their heights relative to surface are related to the energy of laser pulse. In experiment research, we have obtained some photos of surface morphologies, and holes’ depth, diameter and edge raisings’ height are consistent with the data in simulation. And we found a small concavity near the raising on surface, which can prove that the solid–liquid-solid phase transition exists in the processing. Through simulation experiments, we have discovered that gas–liquid interaction may be the mechanism behind the formation of rasing and concavity around the processing area. Further experimental verification will be conducted in future work. Through simulation experiments, we have discovered that gas–liquid interaction may be the mechanism behind the formation of rasing and concavity around the processing area. Further experimental verification will be conducted in future work.

Mechanical properties and joining mechanisms of magnetic pulse welding joints of additively manufactured 316L and conventional AA5052 aluminum alloy

Magnetic Pulse Welding (MPW) is a new solid-phase welding (no heat input and no auxiliaries) technique. This results in joints with almost no brittle intermetallic compounds (IMC) and hence provides excellent joint quality. In this study, 316L fabricated by additively manufactured (AMed 316L) and conventional rolled AA5052 aluminum alloy were welded by MPW. Moreover, it was compared with conventional rolled 316L (C316L). Shear tests were used to characterize the mechanical properties of the joints. Laser confocal microscopy, Scanning Electron Microscope (SEM), and Energy Dispersive Spectroscopy (EDS) were used to characterize the microstructure and elemental diffusion of the joints. It was found that the strength of both joints was higher than that of the base material. In addition, sufficient elemental diffusion was achieved at the weld interface. No significant weld defects and IMC generation were observed at the interface of the AA5052-AMed 316L joint. Finally, Smoothed Particle Hydrodynamic (SPH) was used to analyze the formation mechanism of the transition zone morphology. This study demonstrates for the feasibility of MPW technology for welding additive manufacturing materials.

Experimental Study on Carbon Fiber-Reinforced Polymer Groove Machining by High-Power Water-Jet-Guided Laser.

Due to the excellent properties of carbon fiber-reinforced polymers (CFRPs), such as high strength and strong corrosion resistance, the traditional water-jet-guided laser (WJGL) technology has problems with fiber pull-out and has a small cutting depth when processing CFRPs. Therefore, in this study, we used high-power water-jet-guided laser (HPWJGL) technology to perform groove processing experiments on CFRPs. The effects of four key process parameters, high laser power, pulse frequency, feed rate, and water-jet pressure, on the cutting depth were investigated by a single-factor experiment. The formation mechanism of groove cross-section morphology and the processing advantages of high-power water-jet-guided lasers were analyzed. On this basis, the mathematical prediction model of cutting depth was established by using the response surface method (RSM), and the optimal combination of process parameters was obtained. The mathematical prediction model was verified by experiments, and the error was only 1.84%, indicating that the model had a high reference value. This study provides a reference for the precision machining of HPWJGL technology.

Retraction of "Three-Axial Strain-Triggered Multimode Wrinkles with Tuneable Frictional and Optical Performances".

Wrinkled surfaces driven by stresses/strains are very common in living bodies and geologic structures. The nature-inspired wrinkle patterns have great application prospects in the fields of microfluidics, flexible electronics, smart optics, adhesion, and sensors. Although various wrinkles with single features such as stripes, herringbones, labyrinths, hierarchies, and periodic arrays have been extensively reported, achieving multimode wrinkles in a single sample with large scales is still a challenge. Here, we develop a facile technique to prepare controllable multimode wrinkles in flexible film systems by simply applying three-axial strain. It shows that striped, rippled, and labyrinth-like wrinkles spontaneously form at corners, edges, and center of the triangular film sample, respectively. The morphological characteristics, transition behaviors, and formation mechanisms of such multimode wrinkles are investigated by the experiment, stress theory, and finite element simulation. The frictional and optical performances are obviously anisotropic at the corners and edges, but are isotropic in the center, exhibiting a strong dependence on the wrinkle features. The diffraction properties of light are also well tuneable by exerting mechanical strains. This study helps better understand the wrinkle patterns under three-axial strain and provides a novel way to tailor multimode wrinkles for practical applications.

The damage characteristics and formation mechanism of ultrahigh strength 7055 aluminum alloy under hypervelocity impact

This paper studies the damage morphology evolution of ultrahigh strength 7055 aluminum alloy plate under the hypervelocity impact of aluminum projectile, and analyzes the formation mechanism of crater morphology at different impact velocities. It is found that the impact crater evolves from spherical crown shape to spherical-conical composite shape, and eventually transforms into hemispherical shape with the increase of impact velocity. The evolution of crater shape is highly associated with the ratio of steady-state shock pressure and the strength of the alloy. The variation of crater diameter as a function of impact velocity follows the hypothesis of hemispherical theory, while the crater depth shows a great deviation due to the formation of conical region at the crater bottom and spall fracture at the back of the target. It is demonstrated that the formation of conical crater is related to the poor resistance to shear localization of 7055 aluminum alloy due to its low strain hardening capacity under dynamic loading. Hence, adiabatic shear bands are generated and evolve into shear cracks, thereby causing the formation of conical region at the crater bottom. It is suggested that the resistance to shear localization should be highly considered for the design, evaluation and selection of protection materials for spacecraft.

Microstructure regulation of graphitic carbon nitride nanotubes via quick thermal polymerization process for photocatalytic hydrogen evolution

Among multitudinous photocatalytic materials, graphite carbonitride (g-C3N4) has been widely explored as a new photocatalyst. The g-C3N4 nanotubes with hollow one-dimensional structure can promote carrier migration along the one-dimensional direction, thereby improving the electron-hole separation efficiency, which has always been a hot spot. However, the collapse of nanotubes in long-term thermal polymerization process leads to the decline of photocatalytic performance, which is expected to be further optimized. Herein, we report g-C3N4 nanotubes (TCN) through short time thermal polymerization to ensure the integrity of g-C3N4 skeleton. And the influence of thermal temperature on the internal formation mechanism of nanotube morphology is investigated. Combined with the unique hollow tube structure and complete framework, the migration of photogenerated carriers is significantly accelerated and the photocatalytic hydrogen evolution performance is improved more than 7 times compared with the original g-C3N4. This work provides novel insights into the preparation of g-C3N4 nanotubes for photocatalytic applications.

Experimental simulation of wormhole sanding cavity pattern and microscopic mechanism in heterogeneous weakly-cemented sandstone

Sand production has been a shared problem in the development of weakly-cemented sandstone oil reservoirs. Sanding simulation and prediction are of utmost importance for the production optimization of this type of reservoir. For a long time, research on sand production has been centered on “what is produced from the formation,” such as the size and rate of produced sand. However, “what is left inside the formation,” which is the structural change of the rock after sanding, is also another intriguing and important topic for the management of sand-prone reservoirs. Some related studies have been carried out, and they have proposed that wormhole-like pore throat will appear after sand production, but the precise morphological description and formation mechanism are still lacking. A series of sanding simulation experiments are performed to deepen the understanding of the sanding cavity pattern and its mechanism. The experiments are carried out using a visual sanding simulation apparatus. Through this, the complex wormhole sand production patterns are found and classified into single-branch wormhole cavity patterns and multi-branch wormhole cavity patterns. The extension processes of those different patterns are also demonstrated. Besides, this work discusses the change in the reservoir flowability performance in wormhole sanding mode, and the near-well flowability might be improved by actively inducing weakly-cemented sandstone to create a bigger aperture wormhole sanding pattern. Through the visual microscopic system, the sand competitive detachment mechanism that induces wormhole extending is revealed, along with the cavities concurrent extension mechanism that induces multi-branch wormhole extending. Moreover, this work discusses the microscopic detachment forms which help explain the sand-produced rate from weakly-cemented sandstone. This work enhances and creates a novel understanding of the sanding patterns and mechanisms in weakly-cemented heterogeneous reservoirs, which is beneficial to providing direct guidance for sand production prediction and sand control optimization.