Displacement Values Research Articles

Optimal control of high-rise building structures against earthquake excitations using independent stories as TMD

In this paper, in order to control the behavior of tall building structures against vibrations caused by earthquakes, the parameters of a new passive control system named “independent story” are optimized. This control system is installed like a large tuned mass damper in the main story of the building. Moreover, in order to improve the performance of this control system, six liquid viscous dampers connected from the roof of an independent story to the main story of the building, have also been used to increase damping of the system. The main goal of the present research is to optimize the parameters of this system, including selecting the optimal story/stories of the building to install the independent story/stories, such that the maximum reduction in the mean values of the maximum displacement and maximum acceleration responses of different stories of the building can be obtained, simultaneously. To evaluate the performance of the proposed control system, as a numerical example, a 3-D model of a twelve-story steel building structure is selected for which three degrees of freedom in each story have been considered. Then, a deep search is conducted to find the story/stories of the building at which the independent story control system along with the related supplemental liquid viscous dampers can be constructed/installed such that the best performance of this control system in response reduction of the building can be obtained. Finally, the optimal values of the mass and damping of the supplemental dampers of this system are found to be about 6% of the total mass of the building, and 13 kN-sec/mm, respectively; and the eighth and twelfth stories of the building are the best places for implementation of the proposed control system. By applying the optimal values of all the design parameters of the IS control system, the mean values of the building roof story response reductions were obtained to be about: 28.60% and 26.67% reduction on maximum displacement responses in x and y directions, respectively; and those of the maximum acceleration responses as 43% and 48.89%.

Dynamic factor of safety of rock slopes due to blasting based on critical displacement and critical acceleration

Analysis of slope stability due to blasting based on the pseudostatic principle is considered too conservative because the slope receives a constant maximum seismic load (and hence constant acceleration) without considering the duration of the blast. In reality, the acceleration fluctuates with time and eventually diminishes. One method to analyze the stability of rock slopes due to blasting is to conduct dynamic simulations using Newmark displacement analysis to obtain the dynamic Factor of Safety (FoS) based on the magnitude of critical displacement (ucrit ) and critical acceleration (acrit ). This study was carried out using hypothetical slopes of various rock mass strengths determined from the Rock Mass Rating (RMR). A case study of a highway rock slope excavated using the drill-and-blast method was also carried out to validate the research results. The findings reveal that very good rock (RMR Class I) has FoSdynamic = 11.7, ucrit = 6 mm, and acrit = 0.061g, while very poor rock (RMR V) has FoSdynamic = 1.7, ucrit = 16 mm, and acrit = 0.035g. This result indicates that the smaller the strength of the rock mass, the smaller the critical acceleration and the greater the value of the critical displacement will be. This study reinforces the significance of critical displacement and critical acceleration in assessing the dynamic stability of rock slopes due to blasting.

Seismic studies on energy dissipation device performance for irregular steel structure in different soil conditions using ETABS

Earthquakes are sudden loads that occur and cause low to severe damage to the structure. Based on the intensity of an earthquake, the zones are divided into II, III, IV and V as per IS code 1893:2016(Part-1). Regular, Stiffness Irregular and Mass Irregular G+7 steel building is designed for four zones in ETABS software. Linear Static and Linear Dynamic analyses are performed on all zones for different conditions of soils. In this work, a steel G+7 storeyed structure is developed in ETABS and subjected to seismic loading. For Energy dissipation, the dampers are installed in the building and the analysis process is done. In this research, seismic study is carried out on various models using energy dissipation devices such as fluid viscous damper. The different irregularities in a building in four zones are analyzed with and without using dampers. The study is concluded by comparing displacement and storey shear values for different models.

2.5D Time Series of Postseismic Deformation Following the 2018 Mw 7.5 Palu Earthquake Using Sentinel-1 InSAR

The observed Displacement of Line of Sight (LOS) InSAR can only measure the displacement towards and away from the satellite sensor, making it difficult to provide an intuitive depiction of the deformation source. In the previous studies, research on the characteristics of postseismic deformation mechanisms was conduct by InSAR but only in the vertical component. Therefore, our study attempts to complement this deformation picture by considering both the horizontal and vertical components. It is hoped that this will provide a more comprehensive understanding of the postseismic deformation mechanism of the 2018 Palu earthquake. In this study, we attempted to estimate the 2.5-D surface deformation resulting from the 2018 Palu Earthquake using Sentinel-1 data. The data was then modeled using exponential and logarithmic functions to understand the characteristics of the postseismic deformation mechanism. The 2.5-D surface deformation exhibited variations in horizontal and vertical motions. The East-West (EW) displacement values showed a maximum value of -66.19 mm in the east direction, while the maximum value in the west direction is 75.23 mm. On the other hand, for the Up-Down (UD) displacement, there was a maximum subsidence of -73.40 mm and a maximum uplift of 67.28 mm. To study the characteristics of the transient postseismic deformation, observations were made at 14 points. Postseismic deformation was observed at all locations in the study area. During the period 2018-2021, the time series of the north and east components of the postseismic transients were analyzed using logarithmic and exponential functions. The modeling results showed that the Root Mean Square Error (RMSE) value for the exponential model is 81.80 mm, while for the logarithmic model is 81.38 mm. Therefore, the logarithmic model demonstrated a better fit, indicating that the postseismic deformation mechanism is influenced by afterslip.

Error Correction Method of Platform Displacement for Large Load Static Test

The test platform is an indispensable supporting bearing structure in static tests, which is mainly used to fix test products, simulate the real loading boundary, and provide better operation space for measurement. With the large-scale and complicated spacecraft structure, the static test platform tends to be large-scale, and the displacement measurement error of the static test platform under large load conditions cannot be ignored. The conventional error correction method only uses the displacement value of the monitoring point at the corresponding position of the platform to compensate, ignoring the comprehensive influence of the six degrees of freedom displacement for the test platform on the displacement measurement of the specimen. When it is used for the error correction of the static test of large spacecraft structures, there is a large measurement error affected by the structural size. In view of this, according to the static test requirements of a large spacecraft, a large bearing static test platform with a lateral load of 22 T and a longitudinal load of 52 T is designed, and a displacement measurement error correction method based on six degrees of freedom is proposed. Through the static test of a large spacecraft structure, the method can effectively reduce the displacement measurement error caused by the displacement of the test platform, and the error correction rate can reach 20%.

Calculating the future: Mathematical curriculum in Pharmacy Technician Education

Abstract Introduction The General Pharmaceutical Council’s standards for pharmacy technician education state that the learner should be able to “accurately perform pharmaceutical calculations to ensure the safety of people”1. It is important that any calculations taught reflect current practice and ensure patient safety. Previous research identified four calculation types (moles, molarity, displacement value, dilutions) currently taught in the University of East Anglia (UEA) Certificate of Higher education in pharmacy technician practice that are rarely or never used in the workplace by pharmacy technicians2 resulting in a need to consider the inclusion of these in the future curriculum. Aim To explore whether certain calculations should continue to be taught and/or examined as part of the Certificate in Higher Education in pharmacy technician practice. Methods Ethical approval was obtained through the UEA’s school of education and lifelong research ethics subcommittee (ETH2223-0713). The project team (BS, HK) identified inclusion criteria for prospective participants as registered pharmacy technicians who are current, or previous, educational supervisors of pre-registration pharmacy technicians undertaking the UEA certificate. Prospective participants were invited via email by the project lead (BS) to take part in focus groups to discuss the calculations taught to pre-registration pharmacy technicians. Due to the small number of responses (9 total), two focus groups were undertaken (with a total of 7 participants within the groups). During focus groups, four calculation types and their teaching/assessment within the curriculum were discussed: moles, molarity, displacement value, dilutions. The group then voted to either: 1) continue teaching and examination 2) continue teaching and do not examine 3) remove from teaching/examination and teach as a post-qualification advanced course 4) remove from teaching/examination and do not teach in post-qualification. Transcripts from each focus group including the votes submitted were downloaded from the platform being used and analysed using descriptive statistics and inductive thematic analysis by the project lead (BS)3. Results Participants discussed that there was no expectation for newly qualified pharmacy technicians to be able to complete the discussed calculations in modern practice. Most agreed that that teaching the calculations would support understanding of the underlying scientific concepts but examination on the specific calculations is unnecessary. Votes highlighted the majority (4 out of 7) of participants wanted teaching to continue but not be examined for moles, molarity and dilution calculations, while there was a less consensus on displacement values, though most agreed teaching of this should not be examined. Discussion/Conclusion The changing landscape of pharmacy practice has meant that certain calculations are no longer used in everyday practice and consensus is that examining these is of no benefit to students. Teaching the theory around these calculations may still have a role in allowing students to understand the underlying concepts but examination on the student’s ability to perform these calculations is not considered necessary by workplace supervisors. One highlighted limitation of this study is the limited number of participants resulting in a small sample size to work with. Further review and a change in curriculum should be undertaken to reflect findings.

Analysis of lithotripsy efficiency and stone retropulsion displacement according to pulse characteristics of Ho: YAG laser with Moses effect.

Compared to the conventional Ho: YAG laser, a Ho: YAG laser device has been reported that has a Moses effect to reduce stone retropulsion and increase lithotripsy efficiency. The principle of this equipment is to convert a single laser pulse into two pulses. Most studies on such lasers are limited to lithotripsy efficiency and the prevention of stone retropulsion; studies according to each pulse condition have not been performed. Therefore, the purpose of this study was to quantify the bubble shape, lithotripsy efficiency, and stone retropulsion displacement in a ureteral phantom according to the modulation of the first pulse characteristics of the Moses effect laser under conditions that maintained the total energy and repetition rate. In this study, a Ho: YAG laser system (Holinwon Pro, Wontech Inc., Korea) with an emission wavelength of 2.10 μm and a Moses effect was used. To verify the Moses effect based on the changes in the pulse, a water tank was fabricated, and the ureteral phantom was manufactured in a structure that could be easily installed in the water tank. Additionally, a spherical artificial stone in the ureteral phantom was prepared by mixing calcined gypsum (Cacinated Gypsum) and water at a ratio of 3:1. In the ureteral phantom, a high-speed camera (FASTCAM NOVA S12, Photron Inc.) and visible light were used to record pulse-dependent image analysis of bubbles and stone retropulsion. After mounting the artificial stone in the ureteral phantom, the pulse duration and energy of the first pulse of the Moses effect laser were varied; 30 laser shots for 3 s at a repetition rate of 10 Hz were applied to quantify the lithotripsy efficiency and stone retropulsion displacement, and the experimental values were compared. The fragmentation efficiency was confirmed by measuring the mass before and after the laser pulse application, the original position of the stone retropulsion displacement, and the distance moved. The minimum value of stone retropulsion displacement appeared when the pulse duration of the first pulse was 300 μs, the pulse energy was 100 mJ, and the value was approximately 0.28 mm. The highest fragmentation efficiency was observed under the same conditions, and the mass loss of the artificial stone at that time was approximately 3.7 mg. Quantitative indices, such as lithotripsy efficiency and stone retropulsion displacement, were confirmed using ultrahigh-speed cameras to determine the effect of the first pulse energy and duration of the Ho: YAG laser with the Moses effect on stone removal. It was confirmed that the longer the duration of the primary pulse and the lower the energy, the higher the fragmentation efficiency. In this study, the possibility of manufacturing a laser with an optimal stone-removal effect was confirmed according to the first-pulse condition of the laser with the Moses effect.

Deformation and Stress Law of Surrounding Rock for a Bifurcated Tunnel with a Super-Large Section: A Case Study

The construction method of transitioning from a small cross-section to excavating a super-large cross-section tunnel plays a crucial role in the quality of the final super-large cross-section tunnel and the safety of the tunnel structures and workers during the construction process. The Shenzhen Liantang Bifurcated Tunnel, with a maximum cross-sectional area of 428.4 m2, was the largest cross-sectional tunnel constructed in China in 2018, and there are few engineering projects that can serve as references. To enhance construction safety and achieve the transformation from a two-lane tunnel to a five-lane tunnel, this paper proposes two tunneling methods, namely, the reverse top-heading method and the advance climbing method. Moreover, numerical simulation using MIDAS GTS/NX software was adapted to compare and analyze the stress and deformation characteristics of the surrounding rock in the construction stages using the two methods. The simulation shows that the advance climbing method is more suitable for the construction of the Liantang tunnel. Through on-site monitoring and measurement, the data of peripheral rock vault subsidence, peripheral convergence, and pressure of the supporting structure were assessed. The results show that the maximum values of peripheral rock vault subsidence and peripheral convergence displacement are located in the permissible range of road tunnel vault subsidence. This further verifies the reasonableness of the advance climbing method. This paper not only provide a basis for the construction of the Liantang tunnel but also serves as a reference for construction methods and typical cases for similar super-large-section tunnel projects.

Finite Element Analysis of Subperiosteal Implants in Edentulism—On the Basis of the MaI Implant® by Integra Implants®

The MaI Implants® method offers a modern treatment option for specific patients who lack sufficient bone for traditional screw-based implants. The aim of the article is to use Finite Element Analysis (FEA) to examine the behavior of a subperiosteal implant under actual conditions within the oral cavity and to assess the impact of various mechanical factors on the durability of the MaI Implants®. A strength analysis was conducted using Finite Element Analysis for two models. The first was a single subperiosteal implant, while the second was a model of an arch consisting of two single subperiosteal implants connected by a bar. Based on the obtained results, it can be observed that the increase in load from 100 N to 800 N leads to an increase in displacements throughout the implant. Changing the angle from 90 to 30 degrees resulted in a 576% increase in the average displacement value across all multi-units. Stresses in the multi-units range from 23.7 MPa to 268.5 MPa. The lack of proper stabilization of the implant has the greatest impact on the results of displacements. Such displacements are significant for the later positioning of the implant compared to the initial conditions.

Dynamic Response of Layered Media to Impact Loading (on the Example of Highways)

Introduction. The main way to assess the load-bearing capacity of road structures (which are layered media consisting of materials of different stiffness) is through impact testing. The analysis of the results of these tests is reduced to the consideration of only peak values of vertical displacements without taking into account the change of these parameters in the frequency and time range. At the same time, it is the study of amplitude-frequency characteristics of displacements that can allow solving a number of urgent problems related, for example, to bringing the actual values of vertical displacements to the values under the design modes of operation of the structure.The purpose of the study is to analyze the dynamic response of layered media (road structures) of automobile roads to impact loading, aimed at bringing the actual parameters of the dynamic response to the design values regulated by the requirements of domestic regulatory documents on road design.Materials and Methods. Modern shock loading facilities allow to reproduce the load with a pulse time of 0.03 s, while the design values of elastic moduli are calculated for 0.1 s. To overcome this contradiction, the authors realized an exact solution of the dynamic Lame equation for a multilayered half-space and constructed a series of amplitude-frequency characteristics of displacements, from the processing of which a simplified functional dependence was derived.Results. The methodology of construction of amplitude-frequency characteristics of displacements on the surface of road pavement under impact impact has been developed, which finds its practical application. On the basis of the exact solution of the dynamic Lame equation by means of statistical processing, a simplified regression dependence for vertical displacements is established. An example of calculation of the elastic moduli of the road structure layers taking into account their reduction depending on the time of load application is presented.Discussion and Conclusion. Within the framework of the study, for the first time, a methodology for bringing the actual values of vertical displacements to the values under the design modes of operation of a road structure, based entirely on the computational analysis of its dynamic VAT, in particular, the amplitude-frequency characteristic of deformation under unsteady impact, has been obtained. The developed approach is able to significantly increase the reliability of diagnostics of highway condition, as well as to ensure the unity of measurements and results obtained during the design and diagnostics of roads.

Individual residency behaviours and seasonal long-distance movements in acoustically tagged Caribbean reef sharks in the Cayman Islands.

Understanding how reef-associated sharks use coastal waters through their ontogeny is important for their effective conservation and management. This study used the horizontal movements of acoustically tagged Caribbean reef sharks (Carcharhinus perezi) to examine their use of coastal space around the Cayman Islands between 2009 and 2019. A total of 39 (59.1%) tagged sharks (male = 22, female = 17, immature = 18, mature = 21) were detected on the islands wide network of acoustic receivers. The detection data were used to calculate values of Residency Index (RI), Site-Fidelity Index (SFI) and minimum linear displacement (MLD), as well as for network analysis of individual shark movements to test for differences between demographics, seasons, and diel periods. Sharks were detected for up to 1,598 days post-tagging and some individuals showed resident behaviour but the majority of tagged individuals appear to have been one-off or only occasional transient visitors to the area. Generally, individuals showed strong site-fidelity to different areas displaying linear home ranges of < 20 km. The evidence indicates that there was no pattern of diel behaviour. Tagged sharks generally showed increased movements within and between islands during the summer (April-September), which may be related to breeding activity. Some individuals even made occasional excursions across 110 km of open water > 2,000 m deep between Grand Cayman and Little Cayman. One mature female shark showed a displacement of 148.21 km, the greatest distance reported for this species. The data shows that the distances over which some sharks moved, greatly exceeded the extent of any one of the islands' marine protected areas indicating that this species may be more mobile and dispersive than previously thought. This study provides support for the blanket protection to all sharks throughout Cayman waters, which was incorporated within the National Conservation Act in 2015.

Vibration-reducing modelling of a mecanum wheel based on equivalent stiffness and strength analysis

The mecanum wheel-chair offers unparalleled manoeuverability due to its ability to move in any direction by independently rotating its wheels. However, this innovation, characterized by hub and rollers, brings along a set of challenges, including vertical vibrations induced by successive roller-ground contacts. This manuscript presents a comprehensive investigation into the dynamic features and vertical vibration characteristics of mecanum wheels. Our study focuses on understanding the impact of roller curvature on vertical vibrations. To achieve this, authors employed top-to-top and quadratic mean values of accelerations and displacements. Additionally, authors described the results of a vertical vibration simulation conducted in SolidWorks. A key element of our research involves the implementation of a spring mechanism within the mecanum wheel's centre to dampen vibrations. Through systematic experimentation and analysis, authors determined the optimal geometric arrangement for minimizing vertical vibrations. Our findings reveal a superior design approach for reducing wheel vibrations and enhancing manoeuverability. By addressing this important issue, authors contribute to the advancement of mecanum wheel technology, making it more efficient and practical for a wide range of applications. Specifically, our results demonstrate an impressive 99.98% reduction in vertical vibrations, marking a significant improvement in the mecanum wheel-chair's efficiency and enhancement in wheel efficiency.

Organ-contour-driven auto-matching algorithm in image-guided radiotherapy.

This study aimed to demonstrate the potential clinical applicability of an organ-contour-driven auto-matching algorithm in image-guided radiotherapy. This study included eleven consecutive patients with cervical cancer who underwent radiotherapy in 23 or 25 fractions. Daily and reference magnetic resonance images were converted into mesh models. A weight-based algorithm was implemented to optimize the distance between the mesh model vertices and surface of the reference model during the positioning process. Within the cost function, weight parameters were employed to prioritize specific organs for positioning. In this study, three scenarios with different weight parameters were prepared. The optimal translation and rotation values for the cervix and uterus were determined based on the calculated translations alone or in combination with rotations, with a rotation limit of ±3°. Subsequently, the coverage probabilities of the following two planning target volumes (PTV), an isotropic 5mm and anisotropic margins derived from a previous study, were evaluated. The percentage of translations exceeding 10mm varied from 9% to 18% depending on the scenario. For small PTV sizes, more than 80% of all fractions had a coverage of 80% or higher. In contrast, for large PTV sizes, more than 90% of all fractions had a coverage of 95% or higher. The difference between the median coverage with translational positioning alone and that with both translational and rotational positioning was 1% or less. This algorithm facilitates quantitative positioning by utilizing a cost function that prioritizes organs for positioning. Consequently, consistent displacement values were algorithmically generated. This study also revealed that the impact of rotational corrections, limited to ±3°, on PTV coverage was minimal.

Comparative Analysis of Set-Back Field Jumps In Multi-Storey Building Structures Due To Earthquake Load

Set-back jumping plane out due to earthquake depends. The purpose of this study is to determine what percentage of set-back field jumps are safe in multi-storey building structures when given earthquake loads, evaluate the behavior of building structures when viewed based on displacement and drift ratio and evaluate the effect of the elevation height of the set-back field jumps on building safety.In this study, the building is modeled as high as 7 floors and 6 floors with elevation heights of 28 m and 24 m using the SAP 2000 program which is used to analyze earthquake forces with the variational response spectrum method. The modeling studied was 8 modeling, namely at a height of 7 floors (building structure with set-back out 50%, 30%, 20% and 10%) and at a height of 6 floors (building structure with set-back out 50%, 30%, 20% and 10%). Based on the results of the research that has been done, the percentage of safe set-back exit plane jumps in the 7-storey high-rise building structure is in the modeling with a 10% set-back exit because the displacement value is below the allowable limit. As for the 20% and 30% set-back modeling, the displacement value of the top floor exceeds the allowable limit value. However, if the number of floors in the set-back section is reduced by 1 floor (to 6 floors) the structure is safe for every percentage of modeling.

Analysis of the Variation in Bearing Estimation Error with Frequency Bands for a Source Beneath the Arctic Ice Using a Geophone

To obtain better frequency bands for source bearing estimation, experiments using an ice-mounted geophone were performed at three sites on the Arctic ice cap. By transforming to the frequency domain, errors of the bearing estimation in a number of frequency bands within 1000 Hz and the horizontal peak displacements received by the geophone in the corresponding frequency bands were obtained. After comparing the variation in errors to the peak displacements in the same frequency band, it was found that the errors are related to the peak displacements, and higher peak displacement values mean smaller errors. When the incident angle of the acoustic source and the ice thickness meet certain conditions, some modes of the Lamb waves of the ice plate are excited, the peak displacements in the same frequency band are increased, the errors of bearing estimation are reduced, and the effective frequency band for bearing estimation is broadened. These results provide some new ideas for the bearing estimation of acoustic sources beneath the Arctic ice.

Bending Behavior Analysis of Box Beams with the Reinforcement of Composite Materials for Wind Turbine Blades

Wind turbine blades in excessive wind conditions present extreme deflection problems. For this reason, an analysis of the structural response of composite reinforced box beams is developed. For this purpose, reinforced box beams were fabricated to improve the bending strength in the flapwise direction of the wind turbine blades. The box beams were analyzed with three-dimensional models using the Finite Element Method (FEM) and validated with bending tests at four-points and two-points. The box beam meets the characteristics of lightness and mechanical strength. Experimental four-point bending results showed that reinforced cross-sections decrease displacements by 30.09% and increase their stiffness to 43.41% for a box beam without structural reinforcement. In addition, the two-point bending results showed a difference of 18.98% between the displacements of the beams with structural reinforcements. In the FEM analysis, a maximum error of 11.24% was obtained when correlating the maximum displacement value with the experimental results of the beams.

Biomechanics of internal fixation in Hoffa fractures – A comparison of four different constructs

ObjectiveCompare the biomechanical effectiveness of four different bone-implant constructs in preventing fracture displacement under axial loading. MethodsTwenty artificial femora had a standardized coronally oriented fracture of the lateral femoral condyle, representing a Hoffa fracture classified as a Letenneur type I. Four different fixation constructs were applied to the synthetic bones for biomechanical testing. The constructs consisted of a posterolateral (PL) buttressing locking plate in conjunction with two cannulated lag screws inserted from posterior to anterior (PA) – Group 1; Two cannulated screws inserted from anterior to posterior (AP) without plating– Group 2; A posterolateral (PL) buttressing locking plate in isolation – Group 3; and a combination of two lag screws from anterior to posterior (AP) in addition to a horizontal one-third tubular locking plate – Group 4. An axial load was applied to the fracture site with a constant displacement speed of 20 mm/min, and the test was interrupted when a secondary displacement was detected determining a fixation failure. We recorded the maximum applied force and the maximum fracture displacement values. ResultsGroup 1 demonstrated the highest overall bone-implant axial stiffness with the lowest secondary displacement under loading. Groups 3 and 4 showed equivalent mechanical behavior. Group 2 presented the lowest mechanical stiffness to axial loading. The combination of the one-third tubular locking plate with anterior-to-posterior lag screws (Group 4) resulted in 302 % increase in fixation stiffness when compared to anterior-to-posterior lag screws only (Group 2). ConclusionsThis study confirms the mechanical superiority of having a plate applied parallel to the main fracture plane in the setting of coronally oriented femoral condyle fractures. The addition of a horizontal plate, perpendicular to the main fracture plane, significantly increased the resistance to shearing forces at the fracture site when compared to constructs adopting just cannulated screws. Level of evidenceBiomechanical study

Reaching Large Strains During Simple Shear Experiments Thanks to Sequential Re-Machining of the Free Edges

BackgroundThe simple shear experiment is widely used for the calibration of plasticity models due to straightforward post processing. The specimen can be as simple as a rectangular strip of sheet metal, but the maximum strain is limited by early initiation of fractures from the free edges. Avoiding this drawback has been a major motivation for the development of new specimens with optimized edge geometries or the in-plane torsion test, but at the cost of a more complex analysis of the test and often a reduction of the gauge section.ObjectiveThe objective of the present work is to overcome the initiation of fracture from the free edges during simple shear experiments. Our goal is to double the achievable maximum strain, while keeping the size of the specimen and the post processing simplicity of a standard simple shear test.MethodsA sequential single shear test is proposed, consisting of several two steps sequences on a notched geometry. First, an interrupted shear test is performed up to a specified displacement value. Then, the damaged free edges of the specimen are removed through milling. The specimen is then ready for the following sequence of shear and re-machining.ResultsExperiments are performed on three engineering materials, with up to five loading-machining sequences. The maximum attained effective strain is up to two times the one reached during a monotonic experiment. Numerical simulations are used to validate the shear stress and strain calculations from experimental measurements. Practical recommendations are derived for the choice of the displacement step size and Digital Image Correlation analysis.ConclusionIt is found that the maximum strain attained before the undesired failure of the specimen during simple shear test can be substantially extended through repeated re-machining of the specimen boundaries, enabling behavior identification at larger strains.

Оценка деформационных процессов фотограмметрическим способом в Agisoft Metashape

Active development of digital cameras and computer software has made close-range photogrammetry an extremely popular way to solve various engineering tasks, in particular, to control deformations of constructions and mining objects. Automated measurement of tie points enables reviving traditional techniques of deformation measurement through single shot photogrammetric approach (a zero basis, pseudo parallaxes) at a qualitatively new level. The paper deals with the contour mapping equal displacement method adaptation offered by the first author in the 1970s for processing in Agisoft Metashape. It is proposed to create a virtual basis for two single multi-temporal images by adding a matrix of empty pixels to them. This enables processing those as stereo pair, building virtual point clouds and altitude matrices. In order to test the technique, the authors considered the deflection deformation of various objects under lab conditions and shot their photos with a non-metric camera before and after loading. The obtained images were processed in Metashape, and then the above products were created and contours of equal deformations were plotted. It was found out that the accuracy of displacement value estimation with this method exceeds the spatial resolution of the images more than three times. The technology is applicable for objects deformations monitoring shifting mainly in a single plane, in future it is planned to test it in field at studying slope processes

Molecular Dynamics Simulation and Viscosity Analysis of Red Mud-Steel Slag Glass-Ceramics.

The preparation of glass-ceramics with red mud and steel slag can not only solve the pollution problem caused by industrial waste slag but also produce economic benefits. It is difficult to analyze the high-temperature melt with the existing test methods, so the simulation experiment with molecular dynamics calculation becomes an important research method. The effects of steel slag content on the microstructure of red mud glass-ceramics were studied by molecular dynamics method. The results show that the binding ability of Si-O, Al-O, and Fe-O decreases with the increase in steel slag content. The number of Si-O-Si bridge oxygen increased gradually, while the number of Al-O-Al, Al-O-Fe, and Fe-O-Fe bridge oxygen decreased significantly. The number of tetrahedrons [SiO4] increased, the number of tetrahedrons [FeO4] and [AlO4] decreased, and the total number of three tetrahedrons decreased. The mean square displacement value of Si4+ and O2- increases first and then decreases, resulting in the viscosity of the system decreasing first and then increasing. The molecular dynamics method is used to analyze the structure of red mud-steel slag glass-ceramics on the microscopic scale, which can better understand the role of steel slag and has guiding significance for the experiment of this kind of glass-ceramics.