Axial Shear Research Articles

Simplified calculation models for evaluating the post-earthquake axial load-carrying capacity of RC bridge piers

This study aims to develop simplified calculation models of the post-earthquake axial load-carrying capacity of reinforced concrete columns to determine the post-earthquake traffic flow capacity of the bridges for the evaluation and design process. To this end, the maximum and residual drift ratios are first determined as the engineering demand parameters for the simplified calculation model for the evaluation and design process, respectively. Then, the optimal models describing the relationships between the maximum/residual drift ratio and the post-earthquake axial load-carrying capacity are selected. The analysis results show the normal cumulative model in the coordinate system of ln(x)-y is the optimal relationship model. On this basis, the effects of high-sensitivity parameters (i.e. the axial compressive ratio and shear span ratio) on the post-earthquake axial load-carrying capacity are investigated. Results indicate that the axial compressive ratio negatively affects, while the shear span ratio positively affects the post-earthquake axial load-carrying capacity. Finally, the simplified calculation models of the post-earthquake axial load-carrying capacity are developed from the optimal model and the effects of the high-sensitivity parameters, and with validated high accuracy. The simplified calculation models provide engineers and policymakers with a tool to predict the post-earthquake traffic flow capacity of bridges.

Design, Evaluation & Implementation of a Novel MRI-compatible Physiologic Loading Simulator for Ex-Vivo Joints.

Quantitative magnetic resonance imaging (qMRI), in combination with mechanical testing, offers potential to investigate how loading is related to joint and tissue function. However, current testing devices compatible with MRI are often limited to uniaxial compression, often applying low loads, or loading individual tissues (instead of multiple), while more complex simulators do not facilitate MRI. Hence, in this work, we designed, built and tested (N=1) an MRI-compatible multiaxial load-control system which enables scanning cadaveric joints (healthy or pathologic) loaded to physiologically-relevant levels. Testing involved estimating and validating physiologic loading conditions before implementing them experimentally on cadaver knees to simulate and image gait loading (stance and swing). The resulting design consisted of a portable loading device featuring pneumatic actuators to reach a combined loading scenario, including axial compression (=2.5 kN), shear (=1 kN), bending (=30 N·m) and muscle tension. Initial laboratory testing was carried out; specifically, the device was instrumented with force and pressure sensors to evaluate loading and contact response repeatability in one cadaver knee specimen. This loading system was able to simulate healthy or pathologic gait with reasonable repeatability (e.g., 1.23 to 2.91 % coefficient of variation for axial compression), comparable to current state-of-the-art simulators, leading to generally consistent contact responses. Contact measurements demonstrated a tibiofemoral to patellofemoral load transfer with knee flexion and large contact pressures concentrated over small sites between the femoral cartilage and menisci, agreeing with experimental studies and numerical simulations in the literature.

Experimental study on the cyclic performance of innovative self-centering three-dimensional isolation bearing

To improve vertical seismic isolation and seismic resilience in isolation bearings, this paper introduces an innovative three-dimensional isolation bearing combining a disc-spring system (DSS), a high-damping rubber bearing (HDR), and a horizontal spring system (HSS). The DSS is designed with low vertical stiffness to enhance vertical isolation, while the HSS provides self-centering force to improve the seismic resilience of the HDR. This study first presents a comprehensive theoretical analysis of the horizontal and vertical stiffness composition. The vertical performance of this three-dimensional isolation bearing is attributed to the DSS, while the HSS and HDR jointly contribute to its horizontal performance. Seven specimens were designed and subjected to shear-compression cyclic tests to assess the horizontal and vertical cyclic performance. Experimental parameters included loading amplitude, loading frequency, vertical pre-load, and DSS combinations for vertical tests, and axial compression force, loading frequency, shear strain, and HSS function in horizontal tests. The cyclic performance parameters for the three-dimensional isolation bearing, including equivalent damping ratio, equivalent stiffness, and energy dissipation, was evaluated. In general, the proposed three-dimensional isolation bearing exhibits stable cyclic performance and advantageous seismic resilience, warranting its promotion to practical engineering applications.

A multitask framework with self-attention mechanism for simultaneous detection of axial pressure, shear deformation, and rupture damage in rubber bearings

Base-isolated structures can effectively control structural response, of which rubber bearings are key components. To ensure the proper functioning of rubber bearings, it is important to accurately detect their state. In previous studies, a smart rubber bearing has been proposed to monitor the axial pressure, shear deformation, and rupture damage of rubber bearings. However, owing to the small dataset and limited ability of the prediction model, two problems exist in previous research: (1) the axial pressure, shear deformation, and rupture damage cannot be detected simultaneously and (2) the detection accuracy is not sufficiently high for practical applications. This study solves these problems in three aspects. First, it addresses the issue of limited data by researching and comparing three data augmentation methods. Second, a multitask framework with a self-attention mechanism is established to simultaneously detect axial compression, shear deformation, and rupture damage. Finally, we introduce a two-stage optimization method based on Bayesian optimization and a grid search for the network structure and optimization. The root-mean-square errors for predicting the axial pressure and shear deformation in the test set are 0.19 MPa and 2.04%, which reduced the error by up to 56.8% and 73.0%, respectively, compared to conventional deep neural network models. In addition, the accuracy of rupture damage detection reached 100%.

Magneto-viscoelastic rod model for hard-magnetic soft rods under 3D large deformation: Theory and numerical implementation

The main purpose of this work is to develop a three-dimensional (3D) viscoelastic rod model for hard-magnetic soft (HMS) rods under large deformation which are widely used active structures in soft robotics. To do so, the Simo’s viscoelasticity theory has been rationally incorporated into the geometrically exact 3D curved rod model. The proposed model includes the deformation modes of axial tension, shear, bending, and torsion, which is applicable to the HMS rods with arbitrarily initial curved and twisted geometries under 3D large deformation. The viscoelastic constitutive equations of the HMS rod in the present formulation are formulated, which include the general relaxation functions. To obtain the expression for the magnetic load, the rotation-based magnetic free energy density is introduced, and the governing equations of the HMS rod with magnetic load and body force are presented. To obtain the numerical implementation, an implicit time integration algorithm that simply extends the generalized-α method for the rotation group, and the corresponding variational formulation and its linearization of the rod model are derived. To validate the model, five numerical examples, including 2D dynamic buckling, 3D static, and 3D dynamic problem are presented. The dynamic problems include the dynamic snap-through behavior of a bistable HMS arch and damped oscillation of a quarter arc cantilever under 3D deformation. The simulation results show good agreement with the results reported in the literature.

Rock failure mechanisms based on rheological dynamics

This paper investigates the mechanisms of rock failure related to axial splitting and shear failure due to hoop stresses in cylindrical specimens. The hoop stresses are caused by normal viscous stress. The rheological dynamics theory (RDT) is used, with the mechanical parameters being determined by P- and S-wave velocities. The angle of internal friction is determined by the ratio of Young's modulus and the dynamic modulus, while dynamic viscosity defines cohesion and normal viscous stress. The effect of frequency on cohesion is considered. The initial stress state is defined by the minimum cohesion at the elastic limit when axial splitting can occur. However, as radial cracks grow, the stress state becomes oblique and moves towards the shear plane. The maximum and nonlinear cohesions are defined by the rock parameters under compressive strength when the radial crack depth reaches a critical value. The efficacy and precision of RDT are validated through the presentation of ultrasonic measurements on sandstone and rock specimens sourced from the literature. The results presented in dimensionless diagrams can be utilized in microcrack zones in the absence of lateral pressure in rock masses that have undergone disintegration due to excavation.

Enhancing the fracture toughness of zirconia via highly oriented graphene arrays

Zirconia matrix composites with well-dispersed and highly-oriented two-dimensional graphene arrays were fabricated successfully using tape casting. This significantly improved the fracture toughness (KIC) of zirconia, i.e., an improvement of 64.1 % in KIC, from 4.3 MPa m0.5 to 7.21 MPa m0.5. The interface strengthened by Zr, O and C bonding between zirconia and graphene plays a crucial role in improving the toughness of zirconia. The catastrophic fracture failure mode is transformed into the stable crack propagation behavior with well-oriented graphene arrays. The interface stress transfer behavior analyzed by the shear-lag theory reveals that the graphene layers have little effect on the maximum axial stress and shear stress at graphene/zirconia interface, but the stress distribution are changed. Due to the weak bonding between inner graphene layer, the energy dissipation by graphene pulling-out decreases with increased graphene layers.

A theoretical model for the load-transfer analyses of load distributive compression anchor integrating DSC-based interface nonlinear model

An innovative anchorage technology named load distributive compression anchor (LDCA) has recently been employed in a multitude of geotechnical engineering. The anchoring structure comprises multiple anchor bodies, thereby overcoming the bearing defects associated with conventional load-concentrated anchors and providing superior bearing performance. The complex structural configuration of LDCA considerably complicates the process of load-transfer theoretical modeling. A lack of relevant studies from theoretical solution perspective is yet evident in previous works. In this paper, a theoretical model was proposed for the load-transfer analyses of LDCA, of which the soil-anchor interface mechanical behavior was specially characterized by a disturbed state concept (DSC)-based nonlinear model. The mechanical simulation for the connections in different anchor bodies was incorporated into the theoretical analysis framework through the utilization of finite difference method. Three groups of 3D finite element (FE) models were established to simulate the load-transfer behaviors of LDCAs with different numbers of anchor bodies. The theoretical calculations agree well with the FE numerical results and the in-situ pullout test data, thereby confirming the applicability of the load-transfer theoretical model. The axial force and interface shear stress distributions, as well as the bearing capacity for LDCAs, were discussed based on theoretical calculations and FE simulations. Sensitivity analysis of several key design parameters was conducted to investigate their effects on the bearing capacity of LDCAs. The findings achieved in this study can provide insights into the understanding of the load-transfer behaviors of LDCA, and contribute to the bearing performance evaluation.

Yield Behaviour of Welded I-Shaped Steel Cross-Sections

The limit behaviour of I-shaped welded steel cross-sections subjected to axial force, shear, and bending moment is a crucial matter to ascertain the reliability of framed structures constituted by non-standard beam elements. International standards provide an approximate solution to the problem, and other studies have proposed improved approximate formulations to ascertain the real features of the relevant cross-sections. The present paper is devoted to enhancing the problem of the limit behaviour of plane I-shaped welded steel cross-sections subjected to axial force N, shear T and bending moment M; therefore, new appropriate formulations are proposed in order to define suitable new domains, both in planes N,T, N,M, and M,T and in the space N,T,M. The material is assumed as elastic–perfectly plastic and the Von Mises limit condition is adopted as the resistance criterion. The elastic stresses are described by the Navier formula and the Jourawski formula. The limit stress condition related to the contemporaneous presence of the acting forces is defined as the one that, at each point of the cross-section, fulfils the Von Mises limit condition as equality. The formulation is rigorously devoted to factory-made welded I-shaped steel cross-sections. Some numerical examples are reported in the application stage and useful comparison are carried out, with the results being obtainable by the application of the classical known standard formulae, proving the reliability and effectiveness of the determined domains.

Surface roughness prediction model and surface topography analysis of 2.5D-Cf/SiC in two-dimensional ultrasonic assisted grinding based on GA-BP neural network

Because of the anisotropy and non-uniformity, the grinding surface quality of Cf/SiC composites is difficult to be accurately predicted. The quality of the surface directly determines the assembly accuracy. To better predict the surface quality of 2.5D-Cf/SiC composites, the BP neural network was optimized by genetic algorithm (GA), and the surface roughness prediction model of fiber orientation, ultrasonic amplitude, and machining parameters was established. The empirical formula prediction model of surface roughness was established by the method of multiple linear regression analysis. The results show that the prediction accuracy of GA optimized BP neural network is the best, followed by the empirical formula, and the prediction effect of the BP neural network is the worst. The average absolute percentage error of these three models is 10.045%, 16.912% and 26.6245% respectively. The kinematic models of conventional and two-dimensional ultrasonic-assisted grinding of single particles were established respectively. Based on the kinematic model, the reasons for the reduction of surface roughness by 2D ultrasonic-assisted grinding are explained. According to the orthogonal test results, the surface roughness decreases the most when vs is 0.66m/s, vw is 100mm/min, ap is 150μm along the fiber orientation of 0°, and the maximum percentage of reduction is 53.18%. Increasing the linear speed, reducing the feed speed, reducing the grinding depth, and applying ultrasound can reduce the extrusion pressure along the axis of 0° fiber, and then reduce the length and depth of cracks and thus reduce the surface defects. The axial shear force of the 90° oriented abrasive particles on the fiber is reduced, thus reducing the surface damage caused by torsional deformation. Reduce 3D surface profile and improve surface quality. The maximum percentage reduction of each parameter index is as follows: root mean square height decreased by 28.8%, skew decreased by 88.61%, kurtosis decreased by 48.97%, maximum crest height decreased by 48.55%, maximum sag height decreased by 40.09%, maximum height decreased by 43.93%, and arithmetic mean height decreased by 26.06%.

The performance of waste glass aggregate concrete GFRP-steel double-skin tubular columns under axial compression: Experimental study

In an attempt to alleviate the problem of growing waste glass and fully utilize the excellent material properties of fiber-reinforced polymer (FRP), a novel composite structure, waste glass aggregate concrete glass fiber reinforced polymer (GFRP)-steel double-skin tubular column (WGAC-DSTC), was proposed based on the FRP-concrete-steel double-skin tubular column (DSTC). In the present research, eight WGAC-DSTCs and four waste glass aggregate concrete-filled GFRP tubular columns (WGAC-CFFTs) were investigated to explore their mechanical performance under axial compression. Effects of diverse replacement ratio of waste glass aggregate, GFRP tube thickness, and hollow ratio of column on the mechanical performance of twelve columns were investigated. Meanwhile, this research analyzed and discussed the failure characteristics of columns, load-displacement relationship, ductility coefficient, stiffness coefficient, parameter analysis, ultimate bearing capacity, load-strain relationship and constraint factor. Besides, predicted formulae for estimating the ultimate bearing capacity of WGAC-CFFTs and WGAC-DSTCs were proposed. The research results indicated that (1) Failure mode of the WGAC-DSTCs displayed axial compression failure or shear failure and failure mode of WGAC-CFFTs exhibited mainly axial compression failure; (2) WGAC-DSTCs with 10 % replacement ratio of waste glass aggregate and hollow ratio of 0.4 indicated an increase in the ultimate bearing capacity by 17.24 % and 45.78 %, respectively, as the GFRP tube thickness increased from 1.5 mm to 2 mm and 3 mm. As the column's hollow ratio enhanced from 0.27 to 0.68, the column's ultimate bearing capacity significantly decreased by 7.08 %-60.55 %. The ultimate bearing capacity of WGAC-CFFTs showed a trend of first increasing by 8.33 %-9.41 % but then decreasing by 1.52 % when the replacement ratio of waste glass aggregate rose from 0 % to 30 %; (3) WGAC could replace natural aggregate concrete in traditional DSTC and the bearing capacity could be guaranteed. Besides, it's recommended to utilize 20 % replacement ratio of waste glass aggregate for the WGAC-DSTC whose ultimate bearing capacity enhanced by 15.17 % and possessing optimal mechanical performance; (4) The results calculated utilizing predicted formulae matched well with results of experiment. The application of waste glass aggregate concrete in DSTC can contribute to economic growth and environmental protection and meet the concept of sustainable development.

Experimental Investigation on the Seismic Performance of Novel Prefabricated Composite RC Shear Walls with Concrete-Filled Steel Tube Frame

The present study proposed novel prefabricated composite RC shear walls with a concrete-filled steel tube frame (CCRCSW-CFST) because of the superior seismic performance of shear walls incorporating CFSTs as boundary-restrained members. One cast-in-place reinforced concrete shear wall (RCSW) and seven CRCSW-CFSTs, each varying in axial compression ratios, concrete strengths, and shear span ratios, were designed for experimental analysis. Cyclic loading tests were performed on these specimens, yielding the following results: (1) Compared to reinforced concrete shear walls, CCRCSW-CFSTs demonstrated superior seismic performance, with 14.2% increased ductility and 47.5% greater energy dissipation capacity. (2) Elevating the axial compression ratio in CCRCSW-CFSTs resulted in increased yield strength, peak strength, and stiffness. Conversely, this adjustment also expedited the degradation of stiffness with displacement and decreased both ductility and ultimate deformation. (3) The peak displacement and ultimate displacement of CCRCSW-CFSTs were both increased with an increase in concrete strength. Increasing the axial compression ratio enhanced the initial stiffness of CCRCSW-CFSTs and mitigated the rate at which stiffness deteriorated with increasing displacement. (4) The stiffness, peak and ultimate displacements, peak and ultimate loads, and shear span ratio of CCRCSW-CFSTs were significantly reduced as the shear span ratio was increased. (5) The minor slip between the reinforced concrete panel of the precast slab and the encasing C-shaped steel contributed to an increase in early-stage energy dissipation of the CCRCSW-CFSTs.

A generalized Timoshenko beam with embedded rotation discontinuity coupled with a 3D macroelement to assess the vulnerability of reinforced concrete frame structures

A generalized finite element beam with an embedded rotation discontinuity coupled with a 3D macroelement is proposed to assess, till complete failure (no stress transfer), the vulnerability of symmetrically reinforced concrete frame structures subjected to static (monotonic, cyclic) or dynamic loading. The beam follows the Timoshenko beam theory and its sectional behavior is described in terms of generalized forces and generalized strains. The beam response up to the peak is described by a macroelement, based on plasticity theory, that adopts a 3D failure criterion expressed in terms of axial force, shear force and bending moment. The Embedded Finite Element Method is then adopted to reproduce bending dominated failure, with a global cohesive model that links the cohesive moment to a rotational jump. The formulation allows for remedy of localization phenomena and significant reduction of the necessary computational time. The performance of the proposed simplified strategy is illustrated by comparison with experimental results.

Flexural behaviour of shallow-embedded steel column bases

This paper investigated the flexural behaviour (the initial rotational stiffness and ultimate moment resistance, in particular) of the shallow-embedded column bases through experimental and numerical approaches. Three full-scale tests with different embedded depth ratios (i.e., 0.5, 1.0 and 1.5) were carried out, from which the moment-resisting mechanisms were identified and the effects of the embedded depth ratio on the initial stiffness, moment resistance and ductility were evaluated. The test results were further used to evaluate the accuracy of the available resistance and stiffness models for the shallow-embedded column bases. The resistance models codified in design codes GB 50017-2017 and AISC 341-16 are highly conservative, with an average prediction accuracy of 0.268 and 0.451, respectively; by contrast, the resistance models recently reported in the published articles show better accuracy. The stiffness models are fewer in number and are also inaccurate for the shallow-embedded column bases. Complementary finite-element models were developed and validated. Subsequently, systematic parametric finite-element analyses were performed to investigate the effects of axial force and shear force in the steel column, as well as those of the structural details such as the presence of base plate, arrangement of anchor bolts and width of concrete foundation. Shear force has an adverse effect on both the initial stiffness and moment resistance, and this effect becomes more significant with the increase in the embedded depth ratio; axial compression force leads to an increase in both the initial stiffness and moment resistance, which is more pronounced for embedded column bases with smaller η-values. Among all structural details, the presence of the base plate has the most notable influence on the flexural behaviour of the shallow-embedded column base, increasing both its initial stiffness and moment resistance; comparatively, the effects of the other structural details are minor or even could be ignored.

Comprehensive sex-specific and age-dependent analysis of 4D-flow MRI assessed aortic blood flow-related parameters in normal subjects using single-vendor MR systems and single-vendor software.

Aortic blood flow characterization by 4D flow MRI is increasingly performed in aneurysm research. A limited number of studies have established normal values that can aid the recognition of abnormal flow at an early stage. This study aims to establish additional sex-specific and age-dependent reference values for flow-related parameters in a large cohort of healthy adults. 212 volunteers were included, and 191 volunteers completed the full study protocol. All underwent 4D flow MRI of the entire aorta. Quantitative values for velocity, vorticity, helicity, as well as total, circumferential, and axial wall shear stress [WSS] were determined for the aortic root [AoR], ascending aorta [AAo], aortic arch [AoA], descending [DAo], suprarenal [SRA], and infrarenal aorta [IRA]. Vorticity and helicity were indexed for segment volume (mL). The normal values were estimated per sex- and age-group, where significant differences between males (M) and females (F) were found only for specific age groups. More specifically, the following variables were significantly different after applying the false discovery rate correction for multiple testing: 1) velocity in the AAo and DAo in the 60-70 years age group (mean±SD: (M) 47.0 ± 8.2cm/s vs. (F) 38.4 ± 6.9cm/s, p=0.001 and, (M) 55.9 ± 9.9cm/s vs. (F) 46.5 ± 5.5cm/s, p=0.002), 2) normalized vorticity in AoR in the 50-59 years age group ((M) 27539 ± 5042s-1mL-1 vs. (F) 30849 ± 7285s-1mL-1, p=0.002), 3) axial WSS in the Aao in the 18-29 age group ((M) 1098 ± 203 mPa vs. (F) 921 ± 121 mPa, p=0.002). Good to strong negative correlations with age were seen for almost all variables, in different segments, and for both sexes. This study describes reference values for aortic flow-related parameters as acquired by 4D flow MRI. We observed limited differences between males and females. A negative relationship with age was seen for almost all flow-related parameters and segments.

Analysis of Tall Building by using Different Dimensions Under Wind Load Effects

Abstract: The expense of land is increasing day by day because of rapid increase in the population whereas vegetation is diminishing, due to diminished vegetation contamination is expanded. In this Research paper, we analyze the various types of the dimensions of the building considering them side ratios too and the effect of windward forces on the building in mainly X and Z direction. This paper is about the study of four-building models as Dimensions (30m*30m), (40m*25m), (55m*20m), (80m*15m) having their horizontal Aspect ratios viz. 1, 1.6, 2.75 & 5.33 at an angle of 0 degrees. The height of the building is 90m. Therefore, the research is proceeding to balance out the structure from an increasingly affordable perspective. To find out the best performance and economical for the lateral wind-force resisting system of different models of 25 storey buildings are modelled in STAAD-PRO, assuming the site location as AGRA (Uttar Pradesh), India. For the different structural systems that are compared for minimum and maximum storey displacement, storey drift. The structural system used is prototype. The axial force, shear force, moment, and reactions at various windward sides are used to compare the best performance of the structure. Above all, wind forces in x- direction shows the adequate displacement and drift values when compared to z- direction but from the economic point of view Model-2 gives the satisfactory result from all the above.

Study on Mechanical Properties of Moso Bamboo in Jian'ou City, Fujian Province, China

The original bamboo material of 3 to 4-year-old moso bamboo in Jian'o City, Fujian Province, was used as the research object. Study the change of mechanical properties such as axial compressive strength, bending strength, tensile strength, shear strength, and hardness test. The main work and results of this paper include:Forty-five longitudinal compression specimens on moso bamboo tubes were tested to investigate the effects of different sizes and bamboo knots on the axial compressive strength of the moso bamboo tubes. The mean tensile strength of moso bamboo was found to be 165.13 N/㎟. A total of 27 shear specimens of 5cm moso bamboo tubes were tested, and their average shear strength was 2.61Mpa; he average flexural strength of moso bamboo was 172.48N/㎟. The hardness of moso bamboo specimens was tested using the Janka hardness method. The hardness of each part of Moso bamboo was significantly different.Comparing the mechanical properties of moso bamboo with other wood timber, moso bamboo showed better mechanical properties, the research hoped to provide a theoretical basis and scientific evidence for a comprehensive understanding of the complex mechanical properties of Fujian moso bamboo and the use of moso bamboo in high value-added applications.

Modeling of milling forces in facing process of aluminum alloy AL7075 using the square inserts

Cutting forces play very important in designing the tool machine, cutting tool, and in optimization of machining processes. Modeling and prediction of cutting forces by theoretical methods are quite difficult, so, this study was focused on modeling the cutting force in face milling process using combination of theoretical and experimental methods. This study was performed to model the milling forces (MFs) and determine the milling force coefficients (MFCs) in the face milling process of aluminum alloy Al7075 using square inserts. From theoretical and experimental methods, the relationship of average milling forces (AMFs) and feed per flute (ft) were determined as the linear regression. Using experimental data, the linear regressions of AMFs and feed per flute were determined with high values of determination coefficients (larger than 95 %). MFCs were determined including shear and edge MFCs (tangential shear MFC (Ktc) of 538.127 N/mm2, radial shear MFC (Krc) of 185.967 N/mm2, axial shear MFC (Kac) of -691.297 N/mm2, tangential edge MFC (Kte) of 11.253 N/mm, radial edge MFC (Kre) of 6.991 N/mm, and axial edge MFC (Kae) of –32.971 N/mm. The MF models were successfully verified by comparing the measured and predicted MFs in face milling process of Al7075. The tendency and shape of predicted MFs were quite close to the measured ones. The differences between the predicted and the measured MFs can be due to the several reasons such as the influence of vibrations, the influence of cutting heat, etc., and these are also the limitations of this study. The modeling and prediction methods of this study can be used to model and predict the cutting forces in face milling of other milling types and other pairs of cutting tool and workpiece material as well

Atypical lesional association (Talus Fracture + Pilon Fracture): A case report

Background: Talus fractures represent 3% to 6% of all foot and ankle fractures and are frequently associated with significant morbidity and poor outcomes. They typically result from high-energy trauma, such as motor vehicle accidents or falls from heights. The combination of talar body and tibial plafond fractures is particularly rare, with few cases reported in the literature. Case Report: We present the case of a 20-year-old female who sustained a closed injury to her right ankle after a 6-meter fall. Clinical examination revealed swelling, pain, and bruising without skin opening or neurovascular disturbances. Radiographs and a CT scan identified a non-displaced fracture of the tibial plafond, a medial malleolus fracture, and a posterior process talus fracture. The patient underwent closed reduction and internal fixation with percutaneous screws. At six months post-surgery, she exhibited a good functional outcome with minimal residual pain and slight limitations in ankle movement. Discussion: Talar body fractures commonly result from falls that exert axial compression or shearing forces. Severe cases involve comminution of the ankle and subtalar joints, often accompanied by malleoli fractures. The concomitant fracture of the tibial plafond and talus, as seen in this case, is rare. Managing such injuries is challenging due to high risks of avascular necrosis, subtalar arthritis, and restricted ankle motion. Thorough radiographic and clinical assessments are crucial for effective management, emphasizing the need for careful preoperative planning, precise anatomical reduction, and stable fixation. Conclusion: This rare case of combined talus body and tibial plafond fractures highlights the importance of comprehensive evaluation and appropriate management to minimize serious complications.

Strain localization by diffusion creep of Bridgmanite-Ferropericlase mixture: Application of self-consistent method

In this study, we investigate the finite deformation of a polycrystalline mixture of bridgmanite (Br) and ferropericlase (Fp) by diffusion creep at the lower mantle-like temperature and pressure by using the self-consistent approach. We explore the influence of volume fraction of Fp, viscosity contrast, and strain dependence (effect of shape change) under both axial (coaxial deformation) and simple shear (non-coaxial deformation). Our present study shows: i) the strength (viscosity) contrast between Fp and Br increases with strain since the viscosity of Fp significantly decreases as Fp grain elongates, and (ii) deformation starts from nearly homogeneous strain to finally nearly homogeneous stress under simple shear whereas deformation behavior remains nearly homogeneous strain under axial deformation. A more substantial creep rate partitioning occurs in simple shear than in axial deformation. These results imply that strain localization via diffusion creep might occur in the lower mantle, particularly in regions where the simple shear is dominated (i.e., in the boundary layers (e.g., the D″ layer)).