Deformation Law Research Articles

Molecular dynamics study of the groove-forming mechanism of mechanically scratched grating multilayer aluminum films

For a long time, the forming quality of large area diffraction gratings is restricted by the one-time coating quality and uniformity of large thickness and large area aluminum films. Large thickness coatings, low accuracy of large depth grooves and diamond tool wear problems were the main reasons for the failure of the test to inscribe large area diffraction gratings. Therefore, the use of layered coating process can effectively ensure the uniformity and consistency of large-area and large-thickness grating blanks coated with aluminum film, and improve the high precision of large depth diffraction grating slot type. In order to reveal the mechanism of the groove-forming process of multilayer aluminum films, the microstructure and mechanical properties of different aluminum films were observed. In this article, the removal behavior and mechanism of nanomechanically scratched multilayer aluminum film materials are investigated using a molecular dynamics approach, and the characteristics of multilayer aluminum films scratched into grooves are analyzed in terms of surface morphology, scratching force, structural evolution, dislocation distribution, von Mises stress and shear strain. The results indicate that in the scratching simulation process, multilayer aluminum film has a higher number of removed atoms and a larger atomic displacement compared to single layer aluminum film, which is conducive to precise shape control of the groove. The average tangential force and normal force of multilayer aluminum film show a decreasing trend compared to single layer aluminum film, which helps to scratch grooves and reduce tool wear. The total length of the dislocation lines of the multilayer aluminum film is large, and the distribution area is large, which improves the precision of scratching the grooves. Therefore, an appropriate increase in the number of aluminum film layers has a precise control effect on the groove shape. This study has certain reference significance for analyzing the complex grooving deformation law of grating aluminum film, improving the diffraction efficiency of grating aluminum film, and further improving the manufacturing process of grating aluminum film.

Field Test and Numerical Simulation Study on Water Pressure Distribution and Lining Deformation Law in Water-Rich Tunnel Crossing Fault Zones

Field Test and Numerical Simulation Study on Water Pressure Distribution and Lining Deformation Law in Water-Rich Tunnel Crossing Fault Zones

Study on Deformation of New Tunnels Overcrossing Existing Tunnels Underneath Operating Railways

With the increasing utilization of urban underground space, new tunnels frequently intersect with existing tunnels and operational railways. However, sometimes the excavation and unloading of new tunnels can cause deformation of adjacent existing tunnels and railways, significantly affecting their normal operation. We used finite element software to predict the influence of new tunnel construction on overcrossing existing tunnels and down-traversing operational railways by a dynamic tunneling model based on a connection channel project of the east and west squares of a railway station. This article is not only control the distance between the two tunnels, but the new tunnel and the existing tunnel, as well as the new tunnel and the operation of the railway, the positional relationship between the three, the deformation laws of existing tunnels and operational railways during the construction of new tunnels with different buried depths are analyzed. The results show that the deformation curves of existing tunnels and operational railways present a normal distribution. The maximum deformation position is at the intersection with the new tunnel upon completion of the new tunnel excavation construction. Moreover, an increase in the buried depth of the new tunnel increases the deformation of the operational railway and the existing tunnel. The influence of the depth change of the new tunnel on the settlement of the operational railway is greater than that of the existing tunnel.

Prediction method of long-term creep deformation of mobile phone resin lens module in a harsh temp environment

In recent years, the replacement cycle of digital products such as mobile phones in the market has significantly increased, and the accurate prediction of attenuation under long-term usage conditions of the lens module, storage, and other components has become important. The vast majority of mobile phone lens modules are processed from optical resins, and the degradation of their imaging performance is mainly caused by assembly deformation and long-term creep deformation after a high-temperature reliability test. Therefore, there is an urgent need for a reliable model to describe the long-term creep deformation of the mobile phone resin lens module in a harsh temperature environment. This study proposed a modified derivation method for the parameters of the Maxwell constitutive model to predict the long-term creep deformation of the mobile phone resin lens module in a high-temperature environment. The fitting accuracy of the modified generalized Maxwell model and the time-hardening model were compared through uniaxial compression creep experiments. Long-term creep simulations and experiments were conducted on the mobile phone resin lens module; the deformation law of each component of the mobile phone resin lens module was identified; and the creep deformation mechanism was elucidated. The result shows that the modified generalized Maxwell model has much higher accuracy than the time-hardening model in predicting the long-term creep deformation of different resin materials. When considering the influence of the creep phenomenon, the simulation result matches well with the experimental result, and the high-temperature creep mechanism of the mobile phone resin lens module was clarified. In addition, it was found that the maximum deformation of the lens occurred at the lens with the largest size, which was 2.1 µm, and the position with the largest surface deviation was at the edge of the lens. The prediction method proposed in this study can provide guidance and correction suggestions for the structural design of a mobile phone resin lens module and the rationality of optical design; thus, the imaging accuracy of lens modules will be guaranteed to the greatest extent possible.

Study on calculation model of deflection of prefabricated hole bulkhead under the action of internal explosion

In order to study the plastic deformation law of ship plate frames under the coupling action of internal explosion load and fragment, first, the calculation formula of plastic deformation deflection of the non-porous plate is derived through the law of conservation of energy. According to the numerical calculation results, the influence of the opening position and opening area of the target plate on the deflection gain of the target plate is further explored. The mathematical expression form of the opening area and opening position on the deflection gain of the prefabricated target plate is fitted, and then, the deflection calculation model of the prefabricated target plate is established. It can theoretically predict the deflection of the bulkhead under cabin explosion and has a certain application reference value for ship cabin anti-explosion design and internal explosion damage assessment.

Model Test and Numerical Simulation of Two Typical Close-Fitting Pile–Wall Integrated Structures in Deep Excavation

Compared to conventional support methods, the close-fitting pile–wall integration technique features a minimized construction spacing between the retaining pile and the basement retaining wall. This approach leverages the pile stiffness to minimize the wall thickness and enhance underground space utilization. However, it currently lacks significant discussions and measured data about the interaction laws between the pile and the wall. The model test and finite element method (FEM) are employed to study the deformation and internal force interaction laws of two typical close-fitting pile–wall integrated structures, and a comparison with conventional design is conducted. Furthermore, this study separately investigates the impact of sensitivity factors, specifically the pile–wall stiffness ratio and floor plate stiffness, on both structures during the basement construction and serviceability stages. The test results can closely match the numerical simulation. The study results reveal that the wall impacts the bending moment of the pile to some extent. The internal force in the wall is significantly influenced by the lateral deformation of the pile and the floor plate. Compared to conventional designs, this structure significantly reduces the bending moment of the wall, particularly in the composite structure. Additionally, the analysis of sensitivity factors reveals their considerable influence on the pile–wall interaction.

Research on disturbance influence of goaf residual deformation on simply supported beam bridge

In order to analyze the stability of the bridge above the goaf, the disturbance influence of goaf residual deformation on the bridge is studied. Firstly, an equivalent numerical simulation method of goaf residual deformation evolution process is studied by quantitative analysis the sensitivity of residual subsidence to the rock parameters using the OAT (one-variable-at-a-time). Then, the collaborative deformation of ground, pile, and bridge floor is studied under the condition of a simply-supported beam bridge above the goaf center. Finally, the mechanism of collaborative deformation of ground, pile, and bridge floor is revealed. The results show that the goaf residual deformation process can be obtained by weakening the elastic modulus of fractured rock in the caving zone. At the final residual deformation stage, the subsidence ratio of ground to pile is about 10, and the subsidence ratio of pile to bridge floor is about 2, while the ground horizontal movement ratio of ground to pile is about 7, and the bridge floor horizontal movement can be ignored. The bridge floor is always in the positive curvature influence zone, and the pile has an inhibitory effect on the curvature deformation of the bridge floor. The compression deformation occurs between the piles locations, while the tensile deformation occurs at the pile location. The evolution of negative frictional resistance derived from goaf residual deformation is the main reason for the change in the collaborative deformation law among the ground, pile and bridge floor. This research can provide scientific support and theoretical basis for the design, construction, and protection of the bridge above the goaf center, and can also provide reference for the stability evaluation of bridge above goaf under other conditions.

Influence of Coating Deformation Law on Characteristics of Axisymmetric Contact Problem at Different Stages of Wear

Influence of Coating Deformation Law on Characteristics of Axisymmetric Contact Problem at Different Stages of Wear

Unloading Technology and Application Research of Variable Diameter Drilling in Dynamic Pressure Roadway

Theoretical analysis and numerical simulation are used to study the influence of different parameters of variable diameter borehole pressure relief technology on the surrounding rock and support. A strain-softening model was established to analyze the intrinsic connection between the parameters of variable diameter boreholes and the evolution of surrounding rock stress, deformation law, and support strength. The results show that: (1) With the increase in shallow borehole diameter, it is easy to cause anchor de-anchoring phenomenon. (2) After the deep borehole diameter is more than 250 mm, it transfers the peak of the shallow vertical stress to the deep surrounding rock (about 16 m away from the coal wall). (3) If the position of the variable borehole aperture is set between the anchorage zone and the stress peak of the roadway, the stress transfer effect is better, and the influence and effective binding force on the surrounding rock is smaller. (4) When the spacing is 1.0 m~2.0 m, the vertical stress starts to transfer to the deep surrounding rock, the deformation of the surrounding rock is smaller, and the reduction in the effective binding force of the anchors is smaller. The result can provide a reference for similar production conditions.

Prediction of adjacent single pile deformation induced by tunnel excavation based on the Pasternak model

The construction of metro tunnels in soft ground would cause significant settlement of the ground surface and deformation of buildings and their foundations in the vicinity of the tunnels. The deformation laws of the pile of the neighbouring structures induced by the tunnel construction have not yet been fully identified. This paper analyzed the impact mechanism of tunnel construction on piles based on the Pasternak model, deduced the calculation methods of additional horizontal displacement and additional internal force of piles, and introduced three solution methods. The computational method results have been validated through numerical simulations using coupling of discrete element method and finite difference method and compared to select laboratory data. The results show that the model accuracy is better when the tunnel axis burial depth is less than the pile bottom burial depth. The analysis shows that the tunnel burial depth significantly influences the displacement distribution of the adjacent single pile, while the impact on the peak displacement is insignificant. The thickness of the elastic layer (C) is inversely related to the maximum horizontal displacement and internal force, but it does not impact the distribution patterns of the displacement and internal force. For thickness of the elastic layer (C), the bending moment’s point is constant at 2 m above and below the tunnel axis, whereas the shear force’s point remains constant at the buried tunnel axis’s depth and 4 m above the tunnel axis.

Study of the stress-strain state of the loess soil base of an eccentrically loaded tower foundations, with taking into account the possible water saturation of the soil

This article provides the design of the tower shallow foundations using numerical simulation in the "Midas GTS NX" software. The foundations are four separate structures that perceive the bearing reactions from the tower supports. Depending on the wind load direction, the support reactions change both quantitatively and qualitatively. So, one foundation can accept a compressive force, the other one can accept a pull-out force. In this study, two variants of wind loading are considered: the wind load acts on the tower face or on the tower edge. The geological conditions of the research site are taken as simplified. The soil base consists of one engineering-geological element, which is a loess soil. Numerical simulation of the soil massif was implemented by using volumetric finite elements. An elastic-plastic deformation law and a Mohr–Coulomb failure criterion were applied for these finite elements. The design provided for the calculation of the tower foundation on a natural basis and with the arrangement of a compacted sub-base. Research was carried out for the foundations of the tower construction in four stages: 1) soil base in its natural state; 2) arranged compacted sub-base; 3) natural basis with local water saturation of the soil; 4) compacted sub-base with local water saturation of the soil massif. Simulation of the arrangement of the compacted sub-base occurs by replacing the stiffness of the finite element at a certain stage of the calculation. The soil water saturation simulation algorithm is performed in a similar way - there is a change in the physical and mechanical characteristics of certain finite elements. The localization of saturation zones was chosen from the conditions of the most unfavorable combinations of loads and vertical movements of the foundations. An analysis of the stress-strain state of the soil base of foundations under the tower on a natural base and with the arrangement of a compacted sub-base was performed. The scheme of the applied load on the foundation and the possible local water saturation of the loess soil at the base of the foundations were taken into account

Определение параметров реологической модели по данным лабораторных исследований

Different types of models are used to study the stress-strain behavior of asphalt concrete mixture during compaction. For modeling it is necessary to know the values of model parameters in the whole range of changes in the characteristics of the compacted material. The aim of the paper is to develop a methodology for determining model parameters based on the results of laboratory creep-recovery testing of asphalt-concrete mixture. In the paper, a model reflecting elastic, visco-elastic and visco-fluid properties of the compacted material is adopted. A differential equation representing the law of behavior of the asphalt-concrete mixture layer under load is obtained. The stages of creep-recovery testing are analytically described, namely: rapid loading with a constant load and deformation under this load; load removal and recovery. Initial conditions for the mentioned stages are determined. Taking into account the initial conditions, analytical expressions of the laws of deformation of the model under the action of a constant load and in the process of recovery are obtained. The methodology of laboratory experiments on creep-recovery is described, according to the results of which the required values of the model parameters with minimum absolute error are obtained. The developed methodology allows to determine the parameters of the model describing the stress-strain behavior of asphalt-concrete mixture of different density and temperature. Consequently, it is possible to simulate the behavior of the asphalt concrete mixture layer at the preliminary, main and final stages of compaction in order to determine the effective operating modes of compaction equipment.

Simulation study of compressive mechanical properties of spheroidal cytosolic lattice structures

Ultra-lightweight metallic lattice structures are lightweight functional materials, and the design of their cell elements is a focus of research. Based on the idea of hollow sphere and lattice structure, this paper designs a kind of spherical cytosolic lattice structure, investigates its mechanical properties when compressed by numerical simulation, analyzes its deformation law, derives the nominal stress-strain curve, and investigates the effects of the rod diameter and the cytosolic sphere center distance on the structure’s properties of the effective modulus of elasticity, yield limit, plateau stress, energy absorption and specific energy absorption. The results of the study show that the compressive deformation of the structure exhibits three types depending on the spherical center distance. The mechanical properties of the structure, such as effective modulus of elasticity, yield limit, and plateau stress, show a pattern of decreasing and then increasing with the increase of the spherical center distance, and the minimum value is reached when the spherical center distance is 9.0, but the specific energy absorption of the structure shows a pattern of increasing and then decreasing, and it reaches the maximum value when the spherical center distance is 9.6 mm. The validity of the numerical analog simulation analysis was experimentally verified by 3D printing specimens.

Landslide–Tunnel Interactions and Control Countermeasures under an Orthogonal System

When a tunnel crosses a landslide orthogonally, this interaction can easily lead to instability in both the landslide and tunnel structures. Based on the relative positional relationship between a landslide and a tunnel, we studied the stress mode and deformation characteristics of the tunnel in three positional relationships: within the landslide mass, the sliding surface, and the sliding bed. The tunnel is a typical type located on a sliding surface at an engineering site, so we established a numerical model showing the intersection of the tunnel and the sliding surface. The plastic zone distribution, stress characteristics, and displacement distribution characteristics of the surrounding rock before and after tunnel excavation were studied. Based on the simulation results, we analyzed the control effect of anti-slide piles in controlling the tunnel’s deformation in the surrounding rock from four perspectives: the arrangement of anti-slide piles, the spacing between piles and tunnels, the diameter of anti-slide piles, and the depth of piles embedded in the bedrock. By analyzing the deformation law of the landslide mass and the force characteristics of the tunnel structure under the orthogonal conditions of a tunnel landslide, we provide theoretical guidance for the adoption of anti-slide piles to control instability in tunnel structures.

Monitoring and stability analysis of roadbed & high slope prior to highway construction.

Monitoring in highway projects is significant for the safety, efficiency and quality of construction. This paper proposes a detailed method for monitoring soft-soil roadbed and high-slope, and the layered settlement gauge and total station are employed to carry out experimental monitoring. The law and stability of soft-soil roadbed settlement and deformation under high-slope are further analyzed. The results show that the cumulative values of roadbed settlement and slope platform deformation in general both increase with the increase of monitoring time. However, near 180 days, an abnormal settlement phenomenon was monitored on both sides of the highway with a maximum value of 9.44 mm. This phenomenon was captured at gauge #1, #3, and #4 on observation stake 3, and exact oppositely, it was also observed at gauge #2 on observation stake 4. Moreover, unusual deformations of the high-slope platforms occurred over a period of 10 to 30 days, and these unusual settlements and deformations are indicative of the highway's instability. Therefore, the monitoring on soft-soil roadbed settlement and high-slope deformation can provide reference for highway construction.

Finite-Element Analysis of Temperature Field and Effect on Steel-Concrete Composite Pylon of Cable-Stayed Bridge without Backstays

The backless cable-stayed bridge has the advantages of beautiful shape and reasonable force, but due to the low overall stiffness of the bridge pylon during cantilever construction, it is susceptible to the effect of solar temperature. To reveal the temperature deformation laws and achieve accurate alignment prediction during the installation process of steel–concrete composite pylons in complex environments, a refined numerical simulation model for the 3D bridge temperature field was established based on the proposed automatic sunshine-shadow recognition method. Subsequently, the optimal time periods for construction control are provided. The results of the study show that, during the cantilever construction of the bridge pylon, one pylon column will shade the other pylon column, resulting in asynchronous deformation that can reach 7.6 mm. The effect of solar temperature on the displacement of the bridge pylon is significant, where the maximum daily change in transverse displacement in the cantilevered state of the pylon can reach 33.6 mm, and the maximum change in cable force value can reach 52 kN. In order to mitigate the effect of solar radiation, the best construction time for the bridge pylon is 19:30~9:30, while the tensioning and measurement of the cable should be avoided from 6:00~18:00. This strategy ensures that the control of the pylon top displacement is maintained within 1/4000 of the pylon height, and the error in cable force is kept within 5%.

Analysis of the impact of key strata failure on overlying strata and surface transport patterns

After mining the coal seam under the slope terrain in the southwestern mining area, it is difficult to predict the damage characteristics of the overlying strata and the surface movement and deformation law. To solve this problem, this paper comprehensively analyses the key strata by applying the theory, similarity simulation and the GDEM simulation software, and explores the influence of the change of the key strata’s height and thickness on the damage characteristics of the overlying strata and the surface movement and deformation. By analysing the key strata in the “inclined step” structure, the minimum support force for the key strata not to slip is obtained, and the minimum support force required for the key strata at different levels is deduced. The results of similar tests and numerical simulation analyses show that the vertical displacement of the overburden and surface will be smaller as the key layer is further away from the coal seam. AT the same time, the damage to the overlying strata and the surface is smaller when the key strata fails, and the location of the first subsidence of the slope surface due to mining is usually located in the area close to the bottom of the slope. In the stable structure from the key strata to the ground surface, once the key strata is unstable and broken, the damage and vertical displacement of the ground surface will increase dramatically, thus causing a series of geological disasters such as ground subsidence. Therefore, before the key strata are broken, grouting reinforcement measures are carried out for the rock fissures below the key strata to enhance the tensile strength of the key strata, which can effectively reduce the surface subsidence and deformation.

Study on acoustic emission and local deformation characteristics of feldspar vein-intrusive metagabbro at different angles of splitting

Feldspar vein-intrusive metagabbro is a special geological structure, and different stress angles have an important influence on the fracture mode and deformation characteristics of metagabbro. A Brazilian splitting test on feldspar vein-intrusive metagabbro was performed using three distinct stress angles (0°, 45°, and 90°), and acoustic emission signals and strain characteristics were monitored synchronously during the test. The results showed that the damage pattern of the feldspar vein-intrusive metagabbro was related to the feldspar mineral perforation damage on the main rupture surface. With the increase in stress angle, the percentage of high peak frequency increased gradually. The phenomenon of strain lagging stress appeared in the rock samples before the peak damage. The feldspar minerals played a controlling role in the expansion of microcracks in the feldspar vein-intrusive metagabbro. Significant differences in the local deformation coordination of rocks under different stress angles were observed. The deformation coordination of rock samples with a stress angle of 0° was much lower than that of other rock samples. This study is of great significance for the understanding of the deformation and damage laws of similar geological structures and also provides an important theoretical basis for the stability of deep chambers.

Study on Numerical Simulation of Large-Diameter Borehole Pressure Relief in Deep High-Gas Soft Coal Seams.

The deep highly gassy soft coal seam has the characteristics of high ground stress, high gas pressure, and low permeability. In the process of coal roadway excavation, there are problems such as frequent gas concentration exceeding the limit and easy induction of gas dynamic disasters. To investigate the pressure relief and disaster reduction efficiency of large-diameter boreholes in a deep high-gas soft coal seam, the 8002 high-gas working face of the Wuyang coal mine was taken as the engineering background to study the deformation law of large-diameter boreholes in deep high-gas soft coal seams. A coupled damage-stress-seepage model for pressure relief of large-diameter boreholes in gas-bearing coal seams was constructed based on the Hoek-Brown criterion, the correlation between the damage area and the gas pressure distribution in the gas-bearing coal seam after the pressure relief of boreholes of different apertures was analyzed, and the pressure relief efficiency of different technical parameters "three flower holes" in the roadway head was determined. The law of stress transfer, gas migration, and energy release in the coal seam after pressure relief of a large-diameter borehole under different initial gas pressures was revealed, and the power function equations of the damage range and borehole diameter, maximum stress at the roadway head, and driving distance after pressure relief of a gas-bearing coal seam were determined. Results showed that under the confining pressure of the 8002 working face roadway in the Wuyang coal mine, the pressure relief effect of 250 mm aperture is better, the drilling plastic zone is "butterfly" or "X″-type distribution, and the plastic zone range is positively correlated with the aperture size. Under the arrangement of "three flower holes", the plastic zone is larger and the pressure relief effect is better when the hole spacing is 1.4 m. With the increase of initial gas pressure, the vertical stress above the borehole increases and the pressure relief efficiency decreases. According to the vertical stress distribution within 200 h of borehole pressure relief, the pressure relief process is divided into a coal damage and failure stage, stress balance stage, and hole collapse stability stage. The research results provide a theoretical basis for the prevention and control of coal rock gas dynamic disasters by large-diameter drilling in a deep high-gas soft coal seam.

Research on the deformation law of ultra-thin fiber metal laminates under the synergistic effect of nano-reinforcement and scale effect

At present, titanium alloy/carbon fiber reinforced polymer (TA1/CFRP) laminates, representing the latest fourth generation of fiber metal laminates (FMLs), are predominantly applied in the field of aerospace. The miniaturization of traditional FMLs in thickness or plane size to the micron level for the study of structural properties of ultra-thin laminates will further expand the application of FMLs in the field of micro-devices. Given that carbon nanotubes have a strengthening mechanism in polymers. However, most existing studies have focused on the effect of carbon nanotubes on the properties of macro-scale FMLs, while the enhancement mechanism of the interfacial and mechanical properties of ultra-thin micro-scale FMLs has not been studied, leaving the mechanism still unclear. Based on this, this paper explores the interfacial deformation mode, damage fracture and performance enhancement mechanism of the ultra-thin TA1/CFRP laminates by comparing the parameters of tensile strength and elongation under quasi-static conditions and different process parameters of multi-walled carbon nanotubes content, test temperature, geometry size and grain size. Meanwhile, the correlation law between high-speed tension and quasi-static tension is determined, a 29.3 % increase in tensile strength as the strain rate rises from 0.001 s−1 to 100 s−1, yielding the basic deformation law of ultra-thin FMLs.