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Copyright of B&H Electrical Engineering is the property of Sciendo and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The thermomechanical behavior of materials is known to be sensitive to preexisting defects in their microstructure. In this paper, non-equilibrium molecular dynamics simulations have been used to investigate the effects of the microvoid size on the plastic deformation in single-crystal iron shock-compressed along the [ 001 ] crystallographic direction. The higher the microvoid radius, the faster the kinetics of dislocations. Thus, as the microvoid radius increases, the plastic activity evolves from a regime where the deformation is dominated by twin activities to a regime where both twin and dislocation activities play an essential role and then to a regime where the deformation is dominated by dislocation slip. Furthermore, in both defect-free and defective initial crystal states, the elastic precursor wave is observed to decay with propagation distance, resulting in a constitutive functional dependence of the yielding pressure, σ E , on the plastic deformation rate, ε ˙ p. In the regime where both deformation twinning and dislocation slip play important roles, the constitutive behavior is consistent with the original Swegle–Grady model and is in overall agreement with experimental data and thermomechanical simulations. [ABSTRACT FROM AUTHOR]

The paper deals with the sleeper substructure design for a speed of 200 kph according to the Czech SŽ S4 standard. The paper includes the design of sub-ballast and capping layers. The second part of the paper is focused on transition area design. The conclusion brings recommendations of alterations which would be appropriate to incorporate into the standard. [ABSTRACT FROM AUTHOR]

The deformation behavior of deep excavations is affected by many factors, among which the geological conditions are greatly affected. Hangzhou Bay is affected by marine siltation and river alluvium, and the geological conditions within the urban area of Hangzhou are quite different. In this paper, the geological and deformation data of 79 deep excavation cases in the Hangzhou urban area were collected, and the statistical analysis showed that the deformation control of excavations in the silt area was poor. The average maximum lateral wall displacement of deep excavations of the Hangzhou urban area was 0.41%H (H was the depth of the excavation), the average value of the alluvial area was 0.22%H, and the average value of the silted area was 0.55%H. The influence of geological conditions, wall type, and construction period on the deformation of excavations was compared, and the deformation behavior of excavations in the silted area was clearly affected by various factors. [ABSTRACT FROM AUTHOR]

In this work we propose proof-of-concept methods to detect malfunctions of the braking system in passenger vehicles. In particular, we investigate the problem of detecting deformations of the brake disc based on data recorded by acceleration sensors mounted on the suspension of the vehicle. Our core hypothesis is that these signals contain vibrations caused by brake disc deformation. Since faults of this kind are typically monitored by the driver of the vehicle, the development of automatic fault-detection systems becomes more important with the rise of autonomous driving. In addition, the new brake boosters separate the brake pedal from the hydraulic system which results in less significant effects on the brake pedal force. Our paper offers two important contributions. Firstly, we provide a detailed description of our novel measurement scheme, the type and placement of the used sensors, signal acquisition and data characteristics. Then, in the second part of our paper we detail mathematically justified signal representations and different algorithms to distinguish between deformed and normal brake discs. For the proper understanding of the phenomenon, different brake discs were used with measured runout values. Since, in addition to brake disc deformation, the vibrations recorded by our accelerometers are nonlinearly dependent on a number of factors (such as the velocity, suspension, tire pressure, etc.), data-driven models are considered. Through experiments, we show that the proposed methods can be used to recognize faults in the braking system caused by brake disc deformation. [ABSTRACT FROM AUTHOR]

Layered rock slope exists widely. Because of its special slope structure, it is prone to bending deformation and toppling failure, which is a serious threat to engineering construction and safety operation. At present, the research of layered rock slope still has great innovation potential. During the construction of Wudongde Hydropower Station on Jinsha River, safety and stability problems such as slope geological structure development, face rock unloading and relaxation, and even slip and large deformation were encountered. Through field exploration, it is found that the rock and soil stratification of the slope on both sides of Wudongde Hydropower Station is highly obvious. At present, there is a lack of research on-site long-term displacement monitoring of layered rock high-steep slope, especially for layered slope in complex hydrogeology and construction environment. In order to strengthen the research on the deformation and stability of layered rock slope, this paper analyzes the measured displacement data of Wudongde hydropower station slope, and establishes three-dimensional geological finite element model with the help of numerical simulation software. The stability of the slope is calculated by combining the finite difference method and the strength reduction method. Finally, the evolution mechanism of the deformation of the layered rock slope is explained according to the geological structure characteristics. The main conclusions of this paper are as follows: the layered slope in the dam reservoir area is prone to deformation under the combined action of long-term construction disturbance and fissure water seepage, and the construction disturbance has a strong influence on the artificial excavation area below 1070 m, and the maximum rock mass deformation and surface displacement in the artificial excavation area of the slope reach 92.2 mm and 312.5 mm, respectively. However, the influence of construction disturbance on the natural mountain above 1070 m is limited, the valley deformation of the natural mountain on the left bank of the reservoir area is higher than that on the right bank, and the cumulative deformation is still less than 20 mm. The influence of seepage on the displacement of the area with higher elevation at the top of the slope is more obvious, and the influence of excavation and other disturbances on the displacement of the artificial excavation area with lower elevation is more obvious. The deformation of the river valley in the water cushion pond behind the dam increases slowly, and the change trend of the field deformation data is mostly consistent with that of the numerical calculation. The horizontal shrinkage of the mountains on both sides shows a contraction trend on the whole, and the maximum horizontal shrinkage calculated by numerical simulation is close to 20 mm, which is located at the elevation of 990 m. [ABSTRACT FROM AUTHOR]

An excavator is an off-road vehicle or machine used for several types of construction activities. It has an attachment called a backhoe that is widely used for digging. While digging the earth's massive force works on bucket tips and may bring deformation in it. In this paper an attempt is made to quantify the value of the variables obtained while the all-attached backhoe is considered as a multibody, given in rotation to each joint and simulated in Ansys. The results obtained show that the deformation obtained is small at low rotation and large at high rotation rate. Comparison of the deformation, joint forces and velocity at each set of rotation has been tabulated in x, y and Z directions as well as the overall velocity, total joint force and deformation has also been calculated. This paper provides the base to study and design a multibody system which may undergo deformation so that the end effect may be obtained precisely as required in precision tools and machinery. [ABSTRACT FROM AUTHOR]

The deterioration and deformation of brittle rock generally appear in railway tunnels with the operation of large buried deep tunnel. To investigate the macro-micro fracture and acoustic emission evolution characteristics of brittle rock, this paper conducted the uniaxial compression, scanning electron microscope (SEM), and acoustic emission (AE) signal monitoring under different loading rates. The results showed that the loading rate has an obvious enhancement effect on mechanical parameters. The increased loading rate extends the elastic deformation and improves the bearing strength, elastic modulus and deformation modulus. The fracture patterns include shear fracture, composite fracture, and tension fracture. The oblique shear fracture is transformed into composite fracture and tension fracture with the loading rate increasing. The microscopic fracture shows that increasing loading rate inhibits the evolution of oblique shear fractures and promotes the expansion of tensile fractures. The roughness level of tensile fractures is significantly lower than that of oblique shear fracture and composite fracture. The AE parameters and deformation behavior are characterized by simultaneous evolution. The AE amplitude changes from low-level and low-density distribution to high-level and high-density distribution as the loading rate increases. The AE activity intensity of tensile fracture is significantly greater than that of oblique shear fracture and composite fracture. The warning timeliness of cumulative AE events and cumulative AE energy is generally earlier than the AE b-value under the same loading rate, and the early warning timeliness of cumulative AE events is similar to that of cumulative AE energy. [ABSTRACT FROM AUTHOR]

The initial workpiece diameter is one of the most fundamental process parameters in sheet metal forming, as it determines the resistance of the draw-in material flow. In the context of conventional deep drawing, its critical role has been clearly identified. In the context of electromagnetic sheet forming, however, its role has not yet been adequately addressed. This paper aims to clarify its role, by experimentally and numerically investigating the deformation behavior of circular sheet metal in electromagnetic forming. Various combinations of the initial diameter and discharge voltage were established to induce different deformation behaviors. It was found that adjusting the initial diameter can substantially change the forming height, shape, and thickness distribution by altering the draw-in, which suggests a great improvement in deformation controllability. In summary, this study demonstrates that the initial workpiece diameter could play critical role in deformation control in electromagnetic forming. [ABSTRACT FROM AUTHOR]

For a given material, controllable deformations are those deformations that can be maintained in the absence of body forces and by applying only boundary tractions. For a given class of materials, universal deformations are those deformations that are controllable for any material within the class. In this paper, we characterize the universal deformations in compressible isotropic implicit elasticity defined by solids whose constitutive equations, in terms of the Cauchy stress σ and the left Cauchy-Green strain b , have the implicit form f (σ , b) = 0 . We prove that universal deformations are homogeneous. However, an important observation is that, unlike Cauchy (and Green) elasticity, not every homogeneous deformation is constitutively admissible for a given implicit-elastic solid. In other words, the set of universal deformations is material-dependent, yet it remains a subset of homogeneous deformations. [ABSTRACT FROM AUTHOR]

This paper focuses on the performance of a braced deep excavation in soft soil based on field monitoring and numerical modeling. Laboratory tests were conducted to determine the soil parameters used in the modified Cam-Clay (MCC) model. Intelligent field monitoring means were adopted and a three-dimensional model was established. Spatial and temporal effects induced by the excavation are investigated for the deep-large foundation pit in soft soil. Deformation characteristics of the enclosure structure and the surrounding environment throughout the excavation process are presented. The behaviors of diaphragm walls, columns, the maximum wall deflection rate, ground surface settlement, and utility pipelines were focused on and investigated during the whole excavation process. Besides, the axial forces of the internal supports are analyzed. Based on the measured and simulated data, the following main conclusions were obtained: the numerical simulation results are in good agreement with the measured values, which proves the accuracy of the model parameters; the wall and the ground surface showed the maximum displacement increment at stage 9, which was a coupled product of the "creep effect" of the soft soil in Nanjing, China and the "depth effect" of the excavation; as the excavation progressed, the ground settlement changed from a "rising" to a "spoon-shaped" trend, dvm was measured between dvm = 0.0686%H and dvm = 0.1488%H; the rebound deformation curve of the pit bottom was corrugated, and the depth of disturbance of the pit bottom after the completion of soil unloading was 2-3 times the excavation depth; the closer the pipeline is to the corner of the pit, the less the excavation process will affect the settlement of the pipeline and the less the obvious pit corner effect will occur; the support strength of the buttress and the longest corner brace should be strengthened during the actual construction process to ensure the stability of the foundation deformation. [ABSTRACT FROM AUTHOR]

This paper concentrates on the sensitivity and dynamic simulation of randomly distributed karst cave groups on tunnel stability and connectivity extended ratio based on water-rock interaction using a novel contact dynamic method (CDM). The concept of karst cave group connectivity extended ratio during tunneling and water inrush is proposed. The effects of cave shape and spatial distribution on Qiyueshan tunnel are investigated. Tunnel deformation and damage index, and connectivity extended ratio with uniform random karst cave groups are evaluated. The results demonstrate that the connectivity extended ratio is verified as a crucial judgment in predicting the safe distance and assessing the stability of the tunnel with the karst cave group. CDM model captures the fracture propagation and contact behavior of rock mass, surface flow, as well as the bidirectional water-rock interaction during the water inrush of Qiyueshan tunnel with multiple caves. A larger cave radius and smaller minimum distance between the cave and tunnel increase the deformation and damage index of the surrounding rock. When the cave radius and cave area ratio increase, the failure pattern shifts from overall to local failure. These findings potentially have broad applications in various surface and subsurface scenarios involving water-rock interactions. [ABSTRACT FROM AUTHOR]

The pipe curtain structure method (PSM) is a novel construction method to control ground deformation strictly. Compared with the traditional pipe-roofing and pipe jacking method, the connection between pipes in large spacings using PSM is widely acknowledged as a unique construction procedure. Further study on this connection procedure is needed to resolve similar cases in that the pipes are inevitably constructed on both sides of existing piles. Cutting the steel plate during the connection procedure is the first step, which is crucial to control the safety and stability of the surrounding environment and existing structures. The deformation mechanism and limit support pressure of the cutting steel plate during the connection between pipes in large spacings are studied in this paper, relying on the undercrossing Yifeng gate tower project of Jianning West Road River Crossing Channel in Nanjing, China. A modified 3D wedge-prism failure model is proposed using the 3D discrete element method. Combined with Terzaghi loose earth pressure theory and the limit equilibrium theory, the analytical solutions for the limit support pressure of the excavation face of the cutting steel plate are derived. The modified 3D wedge-prism failure model and corresponding analytical solutions are categorised into two cases: (a) unilateral cutting scheme, and (b) bilateral cutting scheme. The analytical solutions for the two cases are verified from the numerical simulation and in-situ data and compared with the previous solutions. The comparative analysis between the unilateral and bilateral cutting schemes indicates that the bilateral cutting scheme can be adopted as a priority. The bilateral cutting scheme saves more time and induces less ground deformation than the unilateral one due to the resistance generated from the superimposed wedge. In addition, the parametric sensitivity analysis is carried out using an orthogonal experimental design. The main influencing factors arranged from high to low are the pipe spacing, the cutting size, and the pipe burial depth. The ground deformation increases with the increased cutting size and pipe spacing. The pipe burial depth slightly affects the ground deformation if the other two factors are minor. Cutting steel plates in small sizes, excavating soil under low disturbance, and supporting pipes for high frequency can effectively reduce the ground surface subsidence. [ABSTRACT FROM AUTHOR]

The aviation regulations mandate that high-energy rotor components must possesses adequate containment capabilities. Ensuring the containment of the turbine wheel of the air turbine starter is of paramount importance. In this paper, the design thickness of the containment ring was determined and the containment ring deformation was given. Based on the design thickness and deformation of the containment ring, an outer casing structure design method was proposed by using FEM. Then, two containment tests were conducted for different distances between the containment ring and outer casing to validate the outer casing structure design method. The errors of the containment ring deformation are smaller than 7.5%, and the experimental results of the containment process are in accordance with the simulation, validating correctness of the outer casing structure design method. The containment ring deformation rate with the design thickness T = 10 mm is 115%. A safety margin of 1.05 is designed by considering the uniformity of containment ring deformation and the containment ring assembly error. The results illustrate that the deformed containment ring does not damage the outer casing, when the inner diameter of the outer casing is designed as 1.2 times the outer diameter of the containment ring. [ABSTRACT FROM AUTHOR]

Springs are fundamental components in mechanical systems, crucial for ensuring the safety and functionality of mechanisms. Timoshenko's stiffness formula accounts for both bending and torsional energy effects, providing accurate results for small deformations. However, when the deformation becomes large, the spring stiffness becomes a nonlinear problem due to the changing inclination angle and radius during deformation. In this study, we derive a formula for the cylindrical spring stiffness under nonlinear large deformation by considering two assumptions: the invariability of the polar angle at any point and spring wire length during deformation. This formula incorporates the effects of inclination and radius changes on the spring wire. We analyze the stiffness of the cylindrical spring with different initial inclinations using the finite element method (FEM). FEM results were compared with those obtained from Timoshenko's formula, Hiroyuki's formula, and the derived formula. For small deformations, the FEM results matched well with all three formulas. However, for nonlinear large deformations, the calculated results from Timoshenko's formula showed a discrepancy of up to 32.58% compared to the FEM results. The modified Hiroyuki formula also exhibited slightly poorer agreement with the FEM results than the formula proposed in this paper. On the other hand, our derived formula demonstrated excellent agreement with the FEM results for nonlinear large deformations. Therefore, our stiffness formula for cylindrical springs is recommended for mechanical engineering spring design applications involving nonlinear large deformations. [ABSTRACT FROM AUTHOR]

Ball screws are subjected to complex loads during machining processes, which affects the position accuracy of the feed shaft of machine tools. The lack of a reliable model for analyzing the deformation of the ball screw, coupled with the unclear relationship between the deformation of the ball screw and the position error of the feed shaft, makes it challenging to accurately predict and compensate for the position error. The objective of the present research is to investigate the correlation between the deformation of the ball screw and the position error of the feed shaft to improve the accuracy of the machine tool. First, this paper establishes a FEM model to explore the loading and deformation of the ball screw. Secondly, a method for predicting position errors based on the deformation of the ball screw is proposed. Finally, the ball screw-loading test device is used for the position error compensation experiment to verify the reliability of the prediction method. This paper serves as a reference for understanding the generation mechanism of position errors in machine tool feed systems. [ABSTRACT FROM AUTHOR]

The excavation of the pit causes displacement of the surrounding soil, and the excessive deformation causes damage to the existing support structure, which in turn affects the safety of the pit. Reasonable calculation of structural deformation and internal force is crucial for design and construction. Most of the existing theoretical methods simplify the diaphragm wall(DW) as an Euler-Bernoulli beam acting on the Winkler foundation, consider beam-soil interaction, and simplify the soil as isotropic and continuous. However, the shear effects due to the differential deformation of the structure, the unloading stresses acting on the structure due to foundation excavation, and the discontinuous nature of the multilayered soil are neglected. In this paper, an improved analysis method is proposed based on the elastic foundation beam theory. The DW is simplified as a Timoshenko beam and the foundation is simplified as a Vlasov two-parameter model, and a proposed model considering the shear effect of the DW and the interaction of adjacent springs is established, and the proposed method for the deformation and internal force of the DW is obtained by the finite-difference method. The correctness and applicability of the proposed method are verified by numerical simulation and field monitoring data. The effects of equivalent bending stiffness, equivalent shear stiffness, soil elastic modulus, and excavation depth on the deformation and internal force of the DW were further analyzed. The results show that the proposed method can accurately solve the deformation and internal force of the DW, and the maximum errors between the proposed method and the numerical simulation results are only 4.5 % and 1.3 %, respectively. The equivalent bending stiffness of the DW and the elastic modulus of the soil have more significant effects on the horizontal deformation and internal force. The excavation depth is more sensitive to the deformation of the DW, and there is an exponential decay trend between the two. When the equivalent shear and bending stiffnesses reach 6.8×107 kN·m2 and 2.9×107 kN/m, the effect on the horizontal deformation is no longer obvious. The proposed method in this paper can accurately calculate the internal force and deformation of the DW. [ABSTRACT FROM AUTHOR]

During the operation of the drill string, it displays a degree of flexibility. Simultaneously, its dynamic properties, influenced by complex stress conditions, manifest nonlinearity and uncertainty. A comprehensive investigation into the dynamics of flexible drill strings is imperative for deep well drilling. This paper presents a model that simulates random interactions between a flexible drill string and the borehole wall, simplifying the actual drill string model using analogous principles. Dynamic simulation software is utilized for analysis, and an indoor experimental setup has been established. The results reveal that with a constant weight on bit (WOB), higher drill string rotational speeds correlate with increased susceptibility to buckling deformation. Additionally, the critical time for deformation onset exhibits a nearly linear relationship with rotational speed. Maintaining a constant rotational speed, an increase in WOB enhances the likelihood of buckling deformation. The experimental findings suggest a correlation between the drill string's rotation frequency and the WOB. [ABSTRACT FROM AUTHOR]

In the construction of tunnels in the southwestern region of China, the super-deep burial depth results in extremely high ground stress. In the event of encountering soft rock, there is a potential risk of triggering severe deformation disasters, leading to issues such as support structure damage, project timeline delays, and a significant increase in costs. Therefore, there is an urgent need to propose an advanced stress-release technology to address the high-ground-stress issue caused by the super-deep burial in tunnels. The paper takes the Haba Snow Mountain Tunnel as an example and employs various methods such as numerical simulation and on-site monitoring to investigate the advanced stress-release technology of an advanced center drift in super-deep-buried soft-rock tunnels. It also determines the reasonable parameters for the advanced center drift. The research results indicate that setting the area of the advanced center drift to 60% of the area of the main tunnel is more reasonable. Additionally, positioning the vault of the advanced center drift at a distance of 2.0 m from the vault of the main tunnel can reduce stress concentration at the main tunnel's vault. It is also recommended that the main tunnel excavation should lag by two times the tunnel diameter after the advanced center drift excavation, contributing to the effective control of deformation in the main tunnel. The application of the aforementioned design parameters of the advanced center drift in the Haba Snow Mountain Tunnel resulted in a reduction of approximately 29.65% in the deformation of the main tunnel, ensuring the safety of the support structure. The research outcomes presented in this paper can provide valuable reference for similar engineering projects. Highlights: Established a numerical model capable of simulating high-stress soft-rock tunnels and verified it. Proposed a technique for releasing ground stress in high-stress soft-rock tunnels based on advanced center drift. In-depth discussion was conducted on the mechanism of releasing ground stress in the main tunnel through the advanced center drift. The technical parameters of the advanced center drift have been successfully applied on site, and the deformation of the tunnel has been reduced. [ABSTRACT FROM AUTHOR]

In the mechanics of materials, the integral method is often used to calculate the bending deformation of the beam. It is relatively simple to use this method under a single load. However, in real life, the load conditions of most beams are complex and diverse, resulting in more segmentation of the bending equation, too many integral constants, complicated equations involved, cumbersome calculation process, and heavy calculation. In order to solve this problem, the concept of singular function is introduced in this paper. By using a bending equation to express the bending moment internal force of the whole beam, and there are only two integral constants after integration, which greatly simplifies the calculation process and reduces the calculation amount. This paper mainly introduces the properties of the singular function and how to use the singular function to express the bending equation of the beam, and solves the bending deformation of the beam with the boundary conditions, and discusses the application of the singular function in the calculation of the statically indeterminate beam. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Effective monitoring techniques and equipment are essential for the prevention and control of coal and rock dynamic disasters such as rockburst. Based on the fact that there is charge generation during deformation and rupture of coal rock body and the charge signals contain a large amount of information about the mechanical process of deformation and rupture of coal rock, the rockburst charge sensing monitoring technology has been formed. In order to improve the charge sensing technology for monitoring and early warning of rockburst disasters, this paper develops a new generation of portable coal rock charge monitoring instrument on the basis of the original instrument and carries out laboratory and underground field application. The primary advancement involves enhancing the external structure of the sensor and increasing the charge sensing area, which can more comprehensively capture the charge signals from the loaded rupture of the coal rock body. The overall structure of the data acquisition instrument has been improved, the monitoring channels have been increased, and the function of displaying the monitoring data curve has been added, so that the coal and rock body force status can be grasped in time. The results of the experimental study show that the abnormal charge signals can be monitored during the rupture process of rock samples under loading, and the monitored charge signals are in good agreement with the sudden change of stress in the rock samples and the formation of crack extension. There is a precursor charge signal before the stress mutation, and the larger the loading rate is, the earlier the precursor charge signal appears. The charge monitoring instrument can monitor the charge signal of the coal seam roadway under strong mining pressure. In the zone of elevated overburden pressure, the amount of induced charge is large, and anomalously high value charge signals can be monitored when a coal shot occurs. The change trend of the charge at different measuring points of strike and inclination has a good consistency with the distribution of overrunning support pressure and lateral support pressure, which can reflect the stress distribution and the degree of stress concentration of the coal body through the size and location of the charge, foster early warning and analysis of rockburst, and provide target guidance for the prevention and control of rockburst. [ABSTRACT FROM AUTHOR]

In this paper, a novel fractal model for the contact resistance based on axisymmetric sinusoidal asperity is proposed, which focuses on the resistance characteristics of the rough interface at a microscopic scale. By introducing the unique geometric shape of axisymmetric sinusoidal asperity, and combining it with a three-dimensional fractal theory, the micro-morphology characteristics of the rough interface can be characterized more precisely. Subsequently, by conducting a theoretical analysis and numerically solving the deformation mechanisms of asperities on the rough interface, a refined model for contact resistance is constructed. This research comprehensively employs theoretical analysis, numerical simulation, and experimental testing methods to deeply explore the current transmission mechanisms during the contact process of the rough interface. The findings suggest that the proposed model is capable of precisely capturing the intricate interplay of various factors, including contact area, contact load, and material properties, with the contact resistance. Compared to the existing models, the presented model demonstrates significant advantages in terms of prediction accuracy and practicality. This research provides an important theoretical basis and design guidance for optimizing the electrical performance of the rough interface, which has great significance for engineering applications. [ABSTRACT FROM AUTHOR]

In this paper, a forging tool of a new design is proposed, which allows to implement shear and alternating strain in the entire volume of the deformed billet with a smaller change in its initial dimensions. To confirm the effectiveness of the proposed new forging tool in obtaining billets and forgings of the plates and slabs type of the required quality, a laboratory experiment was conducted. During the laboratory experiment, the forging of billets made of the steel 45 was carried out in such forging tools as step-wedge dies of two different variants (proposed and previously known) and in step dies. Analysis of the shape change of billets and the evolution of the microstructure of steel after two deformation cycles showed that the use of the step-wedge dies with a wedge protrusion on the upper die and a wedge cavity on the lower die is more promising for forging billets and forgings of the plates and slabs type with a given level of mechanical properties, since it allows to obtain a fine-grained structure with a smaller change in the initial dimensions of the billet. [ABSTRACT FROM AUTHOR]

In this paper, a near-net discrete clamp motion path control (SF-CMPC)-based stretch-forming method is proposed as a solution for the low-cost high-quality machining of highly curved surfaces. In this approach, the clamps are discretized, the motion paths are designed to control deformation distribution and avoid forming defects, the stretch-forming transition zone can be effectively reduced, the material utilization rate can be increased, and the near-net formation of large surfaces can be achieved. To investigate this method's feasibility, the conventional stretch-forming (SF-C) and SF-CMPC processes are numerically analyzed. The results indicate that, upon increasing the transition zone length via SF-CMPC, the maximum thickness reduction and strain value are reduced by 0.010 mm and 0.0249, respectively, with the dependence of the forming quality on the transition zone length being significantly reduced compared to SF-C. In the formation of surfaces with large curvatures, SF-CMPC's crack risk is lower than SF-C's crack risk, with better adaptability. Through controlling the contact process with a die, the sheet metals' constraint state is improved, the transverse compressive strain can be effectively reduced via friction, and the wrinkling defects can be suppressed. A stretch-forming experiment was carried out on a spherical surface, using self-developed equipment. The feasibility of achieving surfaces' near-net stretch forming by controlling the clamps' motion paths was hereby proven. [ABSTRACT FROM AUTHOR]

When shield tunnels are under complex geological conditions, tunnel damage, decreased structural performance, and shield tunnel deformation and destruction may occur. Therefore, a new type of composite segment and combined splicing joint were suggested and experimentally investigated in this study. According to the test results, the new composite segment effectively enhanced the load capacity of the segment, and the yield and ultimate loads of the segment were increased. Compared with the reference specimen, the ultimate load capacities of the proposed segments with different numbers were 23.8%, 50.0%, and 64.3% greater. Moreover, the combined splicing joint enhanced the initial bending stiffness and load capacity of the segment joint, reduced the opening displacement, and improved the rotational stiffness of the segment joint. The addition of a plug-in joint at the segment joint increased its load capacity by approximately 25%. A parametric study showed that the number and posit ion of the plug-in joint clearly affected the load capacity of the segment joint. In addition to the above test results, reasonable theoretical formulas for the new composite segment and combined splicing joint are given in this paper. [ABSTRACT FROM AUTHOR]

The excavation of pits will induce the vertical displacement of tunnels and lead to engineering problems. The shape as well as size of a pit, and the complex spatial position relationship between the pit and tunnel will induce different deformation responses of tunnel structures; however, the degree to which each factor influences tunnel structure deformation is still unclear. This paper studied the impact of excavation on the deformation of tunnels via a combination of numerical simulation and orthogonal tests. The deformation of tunnels induced by excavation was studied using a numerical method, after which the sensitivity of influencing factors to tunnel deformation was studied by means of range and variance analyses through a four-factor and three-level orthogonal test. The results show that, for a foundation pit with a long side perpendicular to the tunnel longitude, the excavation has the least influence on tunnel deformation. Tunnel deformation increased with an increase in the excavation depth and decreased with an increase in tunnel–pit vertical and horizontal distance. As the plane shape of the foundation pit is 20 m × 45 m, the depth of excavation is 4 m, the pit tunnel vertical distance is 13 m, and the pit tunnel horizontal distance is 28 m, the tunnel has the least deformation. Based on the results of this study, the position relationship between the pit and the tunnel can be optimized in terms of design and construction, and the aim of controlling tunnel deformation can be achieved. [ABSTRACT FROM AUTHOR]

Copyright of China Harbour Engineering is the property of Editorial Office of China Harbour Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The detection of anomalies in dam deformation is paramount for evaluating structural integrity and facilitating early warnings, representing a critical aspect of dam health monitoring (DHM). Conventional data-driven methods for dam anomaly detection depend extensively on historical data; however, obtaining annotated data is both expensive and labor-intensive. Consequently, methodologies that leverage unlabeled or semi-labeled data are increasingly gaining popularity. This paper introduces a spatiotemporal contrastive learning pretraining (STCLP) strategy designed to extract discriminative features from unlabeled datasets of dam deformation. STCLP innovatively combines spatial contrastive learning based on temporal contrastive learning to capture representations embodying both spatial and temporal characteristics. Building upon this, a novel anomaly detection method for dam deformation utilizing STCLP is proposed. This method transfers pretrained parameters to targeted downstream classification tasks and leverages prior knowledge for enhanced fine-tuning. For validation, an arch dam serves as the case study. The results reveal that the proposed method demonstrates excellent performance, surpassing other benchmark models. [ABSTRACT FROM AUTHOR]

This paper introduces a new variable structure controller designed for depth control of an autonomous underwater sensor platform equipped with a variable buoyancy module. To that end, the prototype linear model is presented, and a finite element-based method is used to estimate one of its parameters, the hull deformation due to pressure. To manage potential internal disturbances like hull deformation or external disturbances like weight changes, a disturbance observer is developed. An analysis of the observer steady-state estimation error in relation to input disturbances and system parameter uncertainties is developed. The locations of the observer poles according to its parameters are also identified. The variable structure controller is developed, keeping energy savings in mind. The proposed controller engages when system dynamics are unfavorable, causing the vehicle to deviate from the desired reference, and disengages when dynamics are favorable, guiding the vehicle toward the target reference. A detailed analysis determines the necessary switching control actions to ensure the system reaches the desired reference. Finally, simulations are run to compare the proposed controller's performance with that of PID-based controllers recently developed in the literature, assessing dynamic response and energy consumption under various operating conditions. Both the VBM- and propeller-actuated vehicles were evaluated. The results demonstrate that the proposed controller achieves an average energy consumption reduction of 22% compared to the next most efficient PID-based controller for the VBM-actuated vehicle, though with some impact on control performance. [ABSTRACT FROM AUTHOR]

A steel brace is effective to retrofit old reinforcement concrete (RC) buildings by increasing the horizontal load capacity of structures. However, concrete cracks that easily occur in the surrounding RC members under tension initiate early strength degradation, so this research aimed to develop a new self-centering brace (SCB) with the compression-only capacity such that no tension force is developed in the brace or to the adjoining RC members. Original SCBs have been developed to reduce the residual deformation of structures with a symmetrically flag-shaped hysteretic response. By altering the force transfer mechanism in the original SCB, a compression-only self-centering brace (C-SCB) can be developed under a symmetrically reversed cyclic loading, providing an alternative for the RC building retrofit. This paper first introduces the mechanics and deformation mechanism of the proposed C-SCB. A test program is then conducted on the cyclic tests of a buckling-restrained energy dissipating bar (EDB) to evaluate the energy dissipation. A 3,695-mm-long C-SCB is composed of posttensioning high-strength steel tendons, steel compression members, and buckling-restrained EDBs for the energy dissipation. The C-SCB in tests showed a good compression-only self-centering capability up to an axial displacement of 31 mm, with a maximum axial force of 1,530 kN. No damage of the steel tendons, compression members, or EDBs was found after three phase tests. Finite element analysis further validated the compression-only hysteretic response and mechanics of the C-SCB in a symmetrically reversed cyclic loading. [ABSTRACT FROM AUTHOR]

Wrinkling is a typical failure mode of sandwich structures with thin skins, where the bending deformation of face skins occurs simultaneously in conjunction with transverse stretching deformation of core layer. To analyze the three-dimensional (3D) deformation of wrinkling, a model is required to possess a capability describing completely different deformations at each ply. Therefore, by utilizing the Chebyshev polynomial at each layer of sandwich panels, this paper focuses on proposing a higher-order model to individually illustrate deformations of the skins and the core. By means of the proposed model, a refined triangular element has been constructed. By analyzing the stability of a sandwich plate without stiffeners, the finite-element formulation has been verified by comparing it to the quasi-3D elasticity solutions. In addition, it is anticipated that wrinkling failure can be effectively restrained by designing the stiffener layout. To this end, the influence of stiffener layouts on wrinkling behaviors of sandwich plates has been investigated in detail, and it is found that the capability of resisting the wrinkling deformation can be obviously improved by designing reasonable stiffener layouts. Moreover, the translation between buckling and wrinkling behaviors of sandwich panels with different stiffeners has been also explored, which can help to better understand wrinkling deformation mechanism. In summary, the proposed model can be used to design a reasonable arrangement of stiffeners to resist the wrinkling failure of sandwich panels. [ABSTRACT FROM AUTHOR]

Millimeter-wave (mmWave) antenna arrays are pivotal components in modern wireless communication systems, offering high data rates and improved spectrum efficiency. However, the performance of mmWave antenna arrays can be significantly affected by structural distortions, such as mechanical deformations and environmental conditions, which may lead to deviations in beamforming characteristics and radiation patterns. In this paper, we present a comprehensive sensitivity study of mmWave antenna arrays to structural distortion, employing a coupled structural–electromagnetic statistical concept. The proposed model integrates structural analysis techniques with electromagnetic simulations to assess the impact of structural distortions on the performance of mmWave antenna arrays. In addition, the model incorporates random element positioning, making it easy to analyze radiation pattern sensitivity to structural deformation. Demonstrating the applicability of the model, a 10 × 10 microstrip patch antenna array is designed to assess the performance of the model with a random position error and saddle shape distortion. The results of the model are then compared against the acceptable results from the HFSS software (version 13.0), where a good agreement is observed between the two results. The results show the gain variation and sidelobe level under various degrees of distortion and random errors, respectively. These results provide a guide for design, deployment, and optimization of mmWave communication networks in real-world environments. In addition, the model provides valuable insights into the trade-offs between antenna performance, structural integrity, and system reliability, paving the way for more efficient and dependable mmWave communication systems in the era of 5G and beyond. [ABSTRACT FROM AUTHOR]

Important connections in representation theory arise from resolving a finite-dimensional algebra by an endomorphism algebra of a generator-cogenerator with finite global dimension; for instance, Auslander's correspondence, classical Schur–Weyl duality and Soergel's Struktursatz. Here, the module category of the resolution and the module category of the algebra being resolved are linked via an exact functor known as the Schur functor. In this paper, we investigate how to measure the quality of the connection between module categories of (projective) Noetherian algebras, B, and module categories of endomorphism algebras of generator-relative cogenerators over B which are split quasi-hereditary Noetherian algebras. In particular, we are interested in finding, if it exists, the highest degree n so that the endomorphism algebra of a generator-cogenerator provides an n-faithful cover, in the sense of Rouquier, of B. The degree n is known as the Hemmer–Nakano dimension of the standard modules. We prove that, in general, the Hemmer–Nakano dimension of standard modules with respect to a Schur functor from a split highest weight category over a field to the module category of a finite-dimensional algebra B is bounded above by the number of non-isomorphic simple modules of B. We establish methods for reducing computations of Hemmer–Nakano dimensions in the integral setup to computations of Hemmer–Nakano dimensions over finite-dimensional algebras, and vice-versa. In addition, we extend the framework to study Hemmer–Nakano dimensions of arbitrary resolving subcategories. In this setup, we find that the relative dominant dimension over (projective) Noetherian algebras is an important tool in the computation of these degrees, extending the previous work of Fang and Koenig. In particular, this theory allows us to derive results for Schur algebras and the BGG category \mathcal {O} in the integral setup from the finite-dimensional case. More precisely, we use the relative dominant dimension of Schur algebras to completely determine the Hemmer–Nakano dimension of standard modules with respect to Schur functors between module categories of Schur algebras over regular Noetherian rings and module categories of group algebras of symmetric groups over regular Noetherian rings. We exhibit several structural properties of deformations of the blocks of the Bernstein-Gelfand-Gelfand category \mathcal {O} establishing an integral version of Soergel's Struktursatz. We show that deformations of the combinatorial Soergel's functor have better homological properties than the classical one. [ABSTRACT FROM AUTHOR]

Although squeezing ground may undergo rapid convergences following tunnel excavation, its behaviour is often markedly time dependent due to creep or consolidation. The effects of creep and consolidation on shield tunnelling are comparatively evaluated in two companion papers, with the aim of demonstrating their qualitative similarities and distinctive features. The present, first paper investigates the basic time effects, placing focus on the time development of ground deformations and the complex interaction between ground, tunnel boring machine (TBM) and tunnel support during excavation and during construction standstills. The presented numerical simulations indicate several qualitative similarities between the two mechanisms of time dependency, in respect of the time development of ground deformations, the counter-intuitive behaviour of increasing shield loading with increasing rate of advance under certain conditions, as well as the thoroughly adverse effect of the additional time-dependent deformations taking place during construction standstills on the shield loading. However, they also underscore two prominent differences resulting from the fundamentally different nature of creep (a purely mechanical rheological process) and consolidation (a coupled hydromechanical process): first, the consistently more extensive plastic yielding in consolidating ground, which is partially associated with the seepage forces exerted by the pore water on the solid rock constituents. Second, the role of seepage forces as a potential destabilising agent, particularly for the tunnel face, which does not happen in the case of creep and may be critical for shield and cutterhead jamming. Building upon these investigations, the companion paper compares creep and consolidation with respect to the transferability of experiences about the required thrust force to tunnels of different diameter or to adjacent tunnels. Highlights: Analysis of similarities and differences between the effects of creep and consolidation on mechanised shield tunnelling through squeezing ground. Similar time development of rock deformations and shield loading during advance and during standstills in creep and consolidation. Similar counter-intuitive behaviour of increasing shield loading with increasing advance rate under certain conditions in creep and consolidation. More extensive ground plastification in consolidation than in creep, partially due to the effect of seepage forces on the solid rock constituents. Potential instability due to seepage forces may induce excessive convergences or face extrusion and render shield or cutterhead jamming critical. [ABSTRACT FROM AUTHOR]

In high-speed and heavy-load conditions, ordinary rigid tilting pad journal bearings experience significant contact stress at the pad pivot points, leading to severe pad deformation and increased wear. A flexible structure tilting pad bearing (FSTPB) is presented in this paper, using spring supports to replace the traditional pivot supports and flexible hinge supports. A theoretical calculation model for tilting pad radial journal bearings considering flexible structure deformation is established, and the impact of elastic deformation on the performance of the flexible structure tilting pad bearings is discussed. Based on theoretical research, vibration experiments on flexible tilting pad bearings under different loading conditions were conducted. The influence of various structural parameters on the vibration characteristics of the flexible tilting pad radial bearings was studied. The results indicate that, compared to ordinary tilting pad bearings, flexible structure tilting pad bearings exhibit excellent vibration reduction characteristics at high speeds. Reducing the bearing clearance, lowering the stiffness of the flexible structure, and increasing the offset angle of the flexible structure contribute to enhancing the operational stability of the bearing–rotor system. [ABSTRACT FROM AUTHOR]

The underground hub of Xinghuo Station of M3 Line of Beijing Metro is an integral part of the underground comprehensive hub of Xinghuo Station of high-speed railway, and it is constructed by open-excavation method. Due to the different requirements of the main structure function inside the foundation pit of the hub, the foundation pit adopts the three-level layout. One side of the foundation pit is adjacent to the existing high-speed railway Xinghuo station, and the other side is adjacent to the urban road, the foundation pit is affected by four layers of groundwater. In order to solve the difficulties encountered in the design of the multi-stage foundation pit support structure of the underground hub of the Xinghuo Station on the metro line M3, this paper carries out the research of the foundation pit composite support structure system. Firstly, the spatial layout characteristics, surrounding environment and groundwater occurrence characteristics of the hub foundation pit are analyzed, and the problems of the conventional support structure system are discussed. Based on the concept of graded support and graded water stop, the combined foundation pit support structure system is developed. The paper presents in detail the layout, structural parameters and step sequence of multi-stage foundation pit excavation and support structure system at all stages, then establishes the three-dimensional numerical calculation model of multi-stage foundation pit excavation and support, analyzes the pit bottom uplift and the deformation of the retaining structure, and finally discusses the deformation characteristics of the combined retaining structure of the foundation pit based on the measured results of the deformation of the retaining structure at all stages. The results of numerical simulation and on-site monitoring show that the uplift of pit bottom and the deformation of supporting structure meet the requirements of control values. [ABSTRACT FROM AUTHOR]

Investment casting technology has been increasingly applied in the aerospace field due to its advantages, but investment castings inevitably undergo shrinkage deformation due to the principles of casting. However, the allocation of shrinkage allowance coefficient is not reasonable. The casting sizes are severely deviating from tolerances and the mold needs to be repaired repeatedly. In addressing the problem, the paper discussed the geometric correlation of casting shrinkage deformation and established prediction models for shrinkage allowance coefficient. First, casting experiments and simulations were conducted for H-shaped castings. And the measured pattern allowance coefficients aligned with the simulation results, verifying the reliability of the simulation. Then, the distribution trend of shrinkage along the casting geometric contour was analyzed, and the complex dependence of casting dimensional shrinkage changes on the geometry was discussed. Finally, the paper identified the key geometric parameters that affect shrinkage of each region. And the shrinkage prediction modeling of castings based on geometric parameters was realized. Compared with the conventional constant value for pattern allowance coefficients, the accuracy of the predicted value in assigning shrinkage allowance has been improved by 30.4 pct. The regression model has a good predictive effect on the measured values. The research is beneficial to the dimensional accuracy control in casting production. It can also provide a theoretical basis for the development of shrinkage deformation control technology for complex shape investment castings. [ABSTRACT FROM AUTHOR]

This paper investigates the impact of blade flexibility on the aerodynamics and wake of large offshore turbines using a flexible actuator line method (ALM) coupled to the structural solver BeamDyn in large-eddy simulations. The study considers the IEA 15 MW reference wind turbine in close-to-rated operating conditions. The flexible ALM is first compared to OpenFAST simulations and is shown to consistently predict the rotor aerodynamics and the blade structural dynamics. However, the effect of blade flexibility on the loads is more pronounced when predicted using the ALM compared with using the blade element momentum theory. The wind turbine is then simulated in a neutral turbulent atmospheric boundary layer with flexible and rigid blades. The significant flapwise and torsional mean displacements lead to an overall decrease of 14 % in thrust and 10 % in power compared to a rotor with no deformation. These changes influence the wake through a reduced time-averaged velocity deficit and turbulent kinetic energy. The unsteady loads induced by the rotation in the sheared wind and the turbulent velocity fluctuations are also substantially affected by the flexibility and exhibit a noticeably different spectrum. However, the influence of these load variations on the wake is limited, and the assumption of rigid blades in their deformed geometry is shown to be sufficient to capture the wake dynamics. The influence of the resolution of the flow solver is also evaluated, and the results are shown to remain consistent between different spatial resolutions. Overall, the structural deformations have a substantial impact on the turbine performance, loads, and wake, which emphasizes the importance of considering the flexibility of the blades in simulations of large offshore wind turbines. [ABSTRACT FROM AUTHOR]

Self-centering braces are an attractive new type of brace able to reduce structural residual deformations after earthquakes, with no requirement of major modifications to structural joints. One primary challenge in widespread implementations of self-centering braces is their high demands of prestressing forces, in order to counteract the anti-recentering resistance induced by their energy-dissipation system. This paper introduces a novel self-centering (SC) brace, denoted as a viscoelastic low-prestressing self-centering (VE-LPSC) brace, that needs only a low level of prestressing force to achieve self-centering. The proposed brace incorporates a novel frequency-independent viscoelastic damper (VED) as its energy-dissipation system. The new VED behaves similarly to displacement-based dampers that provide stable stiffness and damping across various frequencies. Meanwhile, as loading ends, the VED does not generate residual anti-recentering forces, unlike conventional velocity-based dampers. Performance tests on the VEDs were first conducted using three specimens to examine the material's deformation capacity, frequency-independent characteristic, fatigue-resistance capacity, and recovery capacity. Then, six full-scale brace prototype specimens were manufactured and tested, considering three levels of prestressing forces (15, 50, and 100 kN). Test results revealed that the brace achieved complete self-centering and consistent stiffness and strength under various frequencies, even with a prestressing force of 15 kN. With conventional steel strand and Belleville springs as its prestressed elements, the new brace was able to elongate 2.27% (corresponding to a story drift of 4.54%) while maintaining its recentering capacity. The VE-LPSC brace may experience some strength degradation after loading lower to 90%, but its capacity can recover to 98% of the original strength after 2 weeks. [ABSTRACT FROM AUTHOR]

In this paper, the concepts of moments and couples in mechanics are examined from a fundamental perspective. Representing a couple by its moment vector is very useful in rigid body mechanics, where the states of internal stresses and deformation are not studied. This is because only the moment of couples appears in the governing equation of moment equilibrium. On the other hand, when considering the state of internal stresses and deformation in continuum mechanics, not only the moment of couples but also the line of action of their constituent parallel opposite forces must be specified. In defining a well-posed problem for a continuum, including the governing equations of moment equilibrium or motion, boundary conditions, and constitutive relations, only the moment of couples (e.g., body couples, couple tractions, couple stresses) appear without specifying the line of action of the constituent parallel forces. Nevertheless, the physical state of stress and deformation in the continuum must be unique and determinate. Therefore, this physical requirement imposes some restrictions on the form of body couples, couple tractions, and couple stresses. Here, the uniqueness of interactions in the continuum is used to establish that the continuum does not support a distribution of body couples or a distribution of surface twisting couple tractions with normal moments. Furthermore, the mechanism of action of the couple traction as a double layer of shear force tractions is established, along with the skew-symmetric character of the couple stress moment tensor. [ABSTRACT FROM AUTHOR]

The article presents a study which examines the rheological properties of long and short fiber bleached kraft pulp suspensions by using a new rotational viscometer. It is stated that the knowledge of pulp suspension rheology is important to obtain optimum design in the pulp and paper industry. Here, the authors state that the experimental rheograms were conformed to the Herschel-Bulkley model. They determine the rheological parameters on temperature, fiber length and pulp consistency to evaluate the influence of these factors to the process. The results revealed that the rheology of the pulp suspension is strongly affected by the pulp's consistency and the other factors mentioned above.

This work is a contribution to the characterization of the papermaking potential of wood pulps. Prevision of this potential developed during the drying process is the scope of this study. The VARIDIM© apparatus allows to measure shrinkage for different loads applied on the paper strip samples with constant air-drying conditions. The dried papers are then tested in an extensometer to determine mechanical properties. The main originality of this study lies in the possibility of classifying pulps by the maximum specific energy they are able to develop during drying shrinkage. [ABSTRACT FROM AUTHOR]

The article discusses that the mathematical expressions of plate instability could be applied to thin webs such as paper that have small but finite plate bending stiffness. It recalls the subject of plate instability and expand the theory to broaden the orthotropic properties of many webs. It examines the effects of web shear stiffness, web tension, and the traction between webs and rollers on troughs and wrinkles. It determines what levels of misalignment are acceptable in each span of a process machine for a given web material.

To develop lightweight and biomimetic structural materials, in this paper, the compressive deformation and mechanical properties of the grid beetle elytron plate (GBEP) with the same core volume as the end-trabecular beetle elytron plate (EBEP) under compression were investigated for the first time. (1) The B-type deformation mode of trabeculae is clarified, which is a higher stage of independent deformation than the Φ-type deformation mode in the beetle elytron plate (BEP). Additionally, the four deformation modes of the BEP are divided into three stages in succession from easy to difficult: C-type, Φ-type and S (B)-type deformation. This paper verifies that the compressive strength and energy absorption capacity of the GBEP increase by 35% and 87%, respectively, relative to those of the grid plate (GP) with the same volume. (2) Although the number of trabeculae of the GBEP is significantly less than that of the EBEP, each trabecula in the GBEP has one more honeycomb wall constraint than each trabecula in the EBEP. The increase range of the compressive properties of the GBEP relative to the GP is greater than that of the EBEP relative to the honeycomb plate (HP). This confirms the prediction that the compressive properties can be effectively improved by appropriately increasing the constraints on the trabeculae. This paper deepens and enriches the knowledge regarding the biomimetic application system of BEPs, lays the foundation for GBEPs, whose preparation is convenient, and accelerates the applications of GBEPs. [ABSTRACT FROM AUTHOR]

The utilization of a supporting tool in Double-Sided Incremental Forming (DSIF) imposes a stabilizing compressive stress through the sheet’s thickness, increasing, thereby, the material’s formability and fatigue life. However, these favorable effects strongly depend on a steady tool-metal contact condition. This work presents a general DSIF control scheme, which augments the conventional position servo-loop with explicit force feedback control. The algorithm is examined for its robustness and effectiveness using complex geometries with varying curvatures and wall angles. The resulting parts have demonstrated enhanced material formability and geometric accuracy. [ABSTRACT FROM AUTHOR]

A better physical understanding of mesoscale and microscale mechanisms behind deformation and failure of paperboard material is important to optimize industrial packaging converting processes and decrease waste. In this study, these mechanisms were investigated using synchrotron X‐ray tomography during in situ continuous uniaxial tensile loading. High spatial and temporal data resolution enabled quantification of rapid changes in the material occurring before, during and after material failure. The evolution of 3D strain fields, fibre orientations and sample thickness showed that deformation and failure mechanisms differ significantly between samples tested in machine direction (MD), cross direction (CD) and 45° from the loading direction. In 45° and CD, gradual failure processes could be followed across several load steps. Immediately after failure, the in‐plane fracture region was significantly larger in both 45° and CD compared to MD. Both fracture characteristics and strain field distributions differed between the three material directions. Significant fibre reorientation was an active deformation mechanism in 45° already from the beginning of the loading, also present in CD after peak load but absent in MD. The MD‐dependent mechanisms interpreted and quantified at the scale of the fibre network in this study can help guide model development and likely have wider applicability to other paper‐based materials. [ABSTRACT FROM AUTHOR]

We compare data from three deep-seated gravity slope deformations (DSGSDs) where paleoseismological techniques were applied in artificial trenches. At all trenches, located in metamorphic rocks of the Italian Alps, there is evidence of extensional deformation given by normal movements along slip planes dipping downhill or uphill, and/or fissures, as expected in gravitational failure. However, we document and illustrate - with the aid of trenching - the evidence of reverse movements. The reverse slips occurred mostly along the same planes along which normal slip occurred, and produced drag folds in unconsolidated Holocene sediments as well as the superimposition of substrate rocks on Holocene sediments. Since trenches are located in diffierent positions with respect to the slope affiected by the DSGSD, it is possible to suggest that reverse slip might occur both at the toe portions of DSGSDs and in their central-upper portions. When the age relationships between the two deformation kinematics can be sorted out, they clearly indicate that reverse slips postdate normal ones. Our data suggest that during the development of long-lived DSGSDs, inversion kinematics may occur in diffierent sectors of the unstable rock mass. The inversion is interpreted as either due to locking of the frontal blocks of a DSGSD, or the relative decrease in the rate of downward movement in the frontal blocks with respect to the rear blocks. [ABSTRACT FROM AUTHOR]

Well water level changes associated with magmatic unrest can be interpreted as a result of pore pressure changes in the aquifer due to crustal deformation, and so could provide constraints on the subsurface processes causing this strain. We use Finite Element Analysis to demonstrate the response of aquifers to volumetric strain induced by pressurised magma reservoirs. Two different aquifers are invoked - an unconsolidated pyroclastic deposit and a vesicular lava flow - and embedded in an impermeable crust, overlying a magma chamber. The time-dependent, fully coupled models simulate crustal deformation accompanying chamber pressurisation and the resulting hydraulic head changes as well as porous flow in the aquifer. The simulated deformational strain leads to centimetres (pyroclastic aquifer) to meters (lava flow aquifer) of hydraulic head changes; both strain and hydraulic head change with time due to substantial porous flow in the hydrological system. Well level changes are particularly sensitive to chamber volume and shape, followed by chamber depth and the phase of the pore fluid. The Young's Modulus and permeability of the aquifer, as well as the strength of pressurisation also have significant influence on the hydraulic head signal. While source characteristics, the distance between chamber and aquifer and the elastic stratigraphy determine the strain field and its partitioning, flow and coupling parameters define how the aquifer responds to this strain and how signals change with time. We investigated a period of pre-eruptive head changes recorded at Usu volcano, Japan, where well data were interpreted using an analytical deformation model. We find that generic analytical models can fail to capture the complex pre-eruptive subsurface mechanics leading to well level changes, due to aquifer pressure changes being sensitive to chamber shape and lithological heterogeneities. In addition, the presence of a pore fluid and its flow have a significant influence on the strain signal in the aquifer and are commonly neglected in analytical models. These findings highlight the need for numerical models for the interpretation of observed well level signals. However, simulated water table changes do mirror volumetric strain and wells can therefore serve as comparatively cheap strain meters that could provide important insights into pre-eruptive dynamics. [ABSTRACT FROM AUTHOR]