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This study focuses on calibrating the linear Drucker-Prager yield criterion for polypropylene under multiaxial loading conditions, using the Arcana fixture to achieve a wide range of triaxiality states. The Drucker-Prager criterion has been adapted for polymers, composites, and metals due to its ability to reflect the influence of hydrostatic pressure on yield stress. This study employs the Arcana fixture, which allows for testing flat plate samples under various angles, thereby simulating different stress states from pure shear to biaxial tension. Additionally, uniaxial compression tests were conducted to extend the range of triaxiality. The material used in this study is Sabic 83MF10, a polypropylene polymer. Samples were prepared by injection moulding and cut to specific dimensions. Tests were performed using a universal testing machine with the Arcana fixture, and the results were analysed to determine the yield strength, pressure, and triaxiality for each sample. The results showed a linear relationship between von Mises stress and hydrostatic pressure, with a friction angle (ß) of 20.65° and material cohesion (d) of 27.81. The numerical simulations in Abaqus confirmed the validity of the DruckerPrager model, accurately reflecting the moment of yielding for the tested samples.

Megathrusts at convergent plate boundaries generate the largest and some of the most hazardous earthquakes on Earth. However, their physical properties, including those influencing fault slip accumulation and release and earthquake‐related surface displacements, are still poorly constrained at critical depths. Here, we combine seismic imaging and geodetic modeling to investigate the structure and mechanical behavior of the Main Himalayan Thrust fault (MHT) in the center of the 2015 Mw 7.8 Gorkha rupture in Nepal. Our results from two independent observations consistently suggest the presence of a channel associated with the MHT with high compliance (shear modulus as low as ∼4 GPa) and strain anisotropy (stiffer in the vertical orientation than in the horizontal), likely arising from a weak subducting layer with north‐dipping foliation. Such mechanical heterogeneity significantly influences the quantification of short‐term fault kinematics and associated earthquake potential, with implications on across‐scale dynamics of plate boundaries in Himalaya and elsewhere. Plain Language Summary The Main Himalayan Thrust fault marks the boundary where the Indian continent slides beneath the Eurasian plate, causing earthquakes like the 2015 magnitude 7.8 event in Nepal. Subsurface images constructed using seismic waves suggest a weak layer surrounding the fault. However, we show that the seismic signature of this layer changes depending on the direction in which the seismic waves travel through it. We compare this information on the subsurface structure to insights from static surface motions during the earthquake. We find that the fit to the motion is poor when we assume the subsurface rock around the fault has the same strength in both horizontal and vertical orientations. The fit improves when we assume the near‐fault rock is stronger under vertical compression than under horizontal compression. This assumption also helps explain the images constructed using seismic waves. We suggest that a strong oriented rock fabric develops in a channel around the plate boundary. The presence of this fabric may have influenced our estimates of fault slip before, during and after great earthquakes. Accurately describing this behavior is crucial for understanding the earthquake potential of plate boundary faults. Key Points Seismic imaging suggests a Main Himalayan Thrust‐associated low‐velocity channel with north‐dipping anisotropic foliation Modeling of InSAR and GNSS data together suggests a weak channel with anisotropic rigidity whose orientation matches seismic constraints The weak anisotropic plate boundary may be related to S‐C fabrics and influence the margin geodynamics on different time scales

Duplex stainless steels (DSSs) are a group of austenitic - ferritic stainless steels featuring an excellent resistance to corrosion and mechanical strength, which makes them the most suitable material to be used in highly corrosive environments. The superior chemical and mechanical properties of DSSs are a result of excessive alloying which renders them very poor machinability. Low machinability combined with high hardness of DSSs generate high temperatures during machining. Exposure to elevated temperatures induces embrittlement, the formation of unwanted intermetallic precipitates and microstructural changes. The high amount of heat generated also shortens the tool life, leads to higher surface roughness and dimensional sensitivity. Hence it is important to study the temperature distribution generated during machining of DSS. In this work, Finite Element modelling and simulation (ABAQUS) for orthogonal and oblique cutting of DSS 2205 was developed using explicit temperature dynamic analysis and meshing was based on Lagrangian formulation. Johnson-Cook material model has been utilized for defining flow stress of the work material. The model developed was validated by experiments conducted using coated WC cutting inserts and the temperatures were measured using thermal camera and thermocouple setup. It was found that the simulated values were able to follow the pattern of the experimental results. The change in temperature distribution due to the coating on the tool was studied.

The presented paper describes accurate distance measurement for a field-sensed magnetic suspension system. The proximity measurement is based on a Hall effect sensor. The proximity sensor is installed directly on the lower surface of the electro-magnet, which means that it is very sensitive to external magnetic influences and disturbances. External disturbances interfere with the information signal and reduce the usability and reliability of the proximity measurements and, consequently, the whole application operation. A sensor fusion algorithm is deployed for the aforementioned reasons. The sensor fusion algorithm is based on the Unscented Kalman Filter, where a nonlinear dynamic model was derived with the Finite Element Modelling approach. The advantage of such modelling is a more accurate dynamic model parameter estimation, especially in the case when the real structure, materials and dimensions of the real-time application are known. The novelty of the paper is the design of a compact electro-magnetic actuator with a built-in low cost proximity sensor for accurate proximity measurement of the magnetic object. The paper successively presents a modelling procedure with the finite element method, design and parameter settings of a sensor fusion algorithm with Unscented Kalman Filter and, finally, the implementation procedure and results of real-time operation.

The endoscopy is the most direct and effective means for digestive tract diseases. Medical workers can conduct a series of manipulations with the help of endoscope, including checking, removing, stripping the diseased tissue or placing the stent. In order to understand the frictional behaviour at the endoscope–oesophagus interface, the finite-element model was analysed by Abaqus in this study. Considering the different modelling conditions, the total force due to frictional stress, frictional dissipation and the maximum Mises stress for the whole model were studied. Results showed that with the increasing amplitude, coefficient of friction and decreasing diameter, the total forces due to the frictional stress and the FD increased obviously. It did not present a clear difference with the variable distance for overlapping parts (region L). The positions of maximum Mises stress for the whole model under different conditions mainly focused on the initial part of the region R. The maximum Mises stress between different diameters showed a big difference. The results can provide the basic data for the finite-element modelling of frictional behaviour of human tissue.

State-of-the-art slim floor systems are a newest addition to the composite construction industry and several types are currently being used for building and construction purposes. Asymmetric slim floor beams are a type of slim floor systems which consist of a rolled section with a larger bottom flange. The larger bottom flange induces asymmetry and offers an efficient use of the material strength as a composite beam. It also offers a larger area to support the steel decking and pre-cast slab units during the construction of floor. Experimental and analytical investigations on response of asymmetric slim floor beams have shown that these beams offer a higher fire resistance in comparison to the conventional composite systems with down-stand steel beams. Previous investigations on these beams have been conducted in standard fire exposure conditions, hence, their response to natural fire scenarios still deems further examination. This study addresses response of asymmetric slim floor beams in natural fire exposure conditions. For this purpose, finite element models developed and verified by the authors are employed to study the thermal and structural response of slim floor beams in fast and slow parametric-fire exposures. Results obtained show that the asymmetric slim floor beams behave differently in parametric-fires in comparison to that in standard fire exposure conditions. Asymmetric slim floor beams continued to support the loads for the whole duration of parametric fires without undergoing excessive deflections and offering a better fire resistance. Unlike in case of the standard fire where the temperatures keep on increasing throughout the duration, temperatures on the slim floor beams decrease after reaching a maximum point in parametric-fires. It was found that for fast parametric-fires, the thermal gradient across the section is more severe as compared to that for the slow parametric-fires at earlier stages of fire exposure. In case of the fast parametric-fires, the rise and fall of temperatures on the slim floor beams are rapid while in case of the slow parametric-fire, these variations in temperatures are subtle. It was observed that the structural response of slim floor beams in standard and parametric fires depends on the average temperature across the steel section. Deflections predicted for the beams were found to be directly related to these average temperatures. Outcomes of this study will benefit in understanding the response of asymmetric slim floor beams in natural fire conditions and will aid to develop simple fire design methods for future use.

The Benedictine Monastery of São Miguel de Refojos, located in Cabeceiras de Basto (Portugal), is a monumental complex and a distinctive example of the 18th century Portuguese Baroque architecture. This study addresses the state of conservation of the church as well as the evaluation of its structural behavior and seismic performance. An initial inspection and diagnosis campaign revealed that the structure presents low to moderate damage and other non-structural issues generally associated with high levels of moisture and water infiltration. In order to study the structural performance, a three-dimensional (3D) numerical model was prepared based on the finite element method. This model was calibrated with respect to dynamic identification tests and nonlinear static analyses were then performed to evaluate the seismic behavior. Capacity curves, deformations, crack patterns, and failure mechanisms were used to characterize the structural response. Additionally, the safety evaluation for horizontal actions was verified by means of limit analysis. An overall good agreement was found between the results of the pushover and the limit analyses. To conclude, the present work provides a comprehensive evaluation of the state of conservation of the church and verifies the safety condition of the structure for seismic actions.

Finite Element simulations are a robust way of investigating cardiac biomechanics. To date, it has only been performed with the left ventricle (LV) alone for fetal hearts, even though results are likely different with biventricular (BiV) simulations. In this research, we conduct BiV simulations of the fetal heart based on 4D echocardiography images to show that it can capture the biomechanics of the normal healthy fetal heart, as well as those of fetal aortic stenosis better than the LV alone simulations. We found that performing LV alone simulations resulted in overestimation of LV stresses and pressures, compared to BiV simulations. Interestingly, inserting a compliance between the LV and right ventricle (RV) in the lumped parameter model of the LV only simulation effectively resolved these overestimations, demonstrating that the septum could be considered to play a LV-RV pressure communication role. However, stresses and strains spatial patterns remained altered from BiV simulations after the addition of the compliance. The BiV simulations corroborated previous studies in showing disease effects on the LV, where fetal aortic stenosis (AS) drastically elevated LV pressures and reduced strains and stroke volumes, which were moderated down with the addition of mitral regurgitation (MR). However, BiV simulations enabled an evaluation of the RV as well, where we observed that effects of the AS and MR on pressures and stroke volumes were generally much smaller and less consistent. The BiV simulations also enabled investigations of septal dynamics, which showed a rightward shift with AS, and partial restoration with MR. Interestingly, AS tended to enhance RV stroke volume, but MR moderated that down.

There is a great interest in improving mechanical testing of small samples produced in the laboratory. Plane strain compression is an effective test in which the workpiece is a thin sheet. This provides great potential for testing samples produced by high-pressure torsion. Thus, a custom tool was designed with the aim to test 10 mm diameter discs processed by this technique. Finite element analysis is used to evaluate the deformation zone, stress and strain distribution, and the accuracy in the estimation of stress–strain curves. Pure magnesium and a magnesium alloy processed by high-pressure torsion are tested using this custom-made tool. The trends observed in strength and ductility agree with trends reported in the literature for these materials.

This paper deals with the improvement of fatigue life of AISI 1040 steel components by using a High Power Diode Laser (HPDL). First, the meaningfulness of each operational parameter was assessed by varying the experimental laser power and scan speed. After laser treatment, fatigue tests were performed to investigate the influence of laser processing parameters on the material resistance. The fatigue tests were carried out by using a rotating bending machine. Wöhler curves were obtained from the analysis of experimental results. Second, in the light of experimental findings, a 3D transient finite element method for a laser heat source, with Gaussian energy distribution, was developed to predict the temperature and the depth of the heat affected zone on the workpiece. The model allows us to understand the relationship between the laser treatment parameters and the fatigue enhancement of the components. HPDL was found to significantly increase the fatigue life of the irradiated workpieces, thus revealing its suitability for industrial applications.