Shear Stress Distribution Research Articles

Research on ultrasonic testing method for tangential contact stress based on equivalent medium theory

As a weak link, the joint surface of machine tools directly affects the stiffness and machining accuracy of the entire machine tool. However, obtaining the distribution of contact stress is a key problem that urgently needs to be solved in exploring the mechanical properties of joint surface connections. In this paper, a tangential contact stress ultrasonic testing method based on the equivalent medium theory is proposed, providing data support for accurately characterizing the contact state of the joint surface. A virtual material model of rough contact interface based on fractal theory is established to explore the coupling relationship between the propagation speed of ultrasonic critical refracted longitudinal waves, the tested object’s material parameters, and stress. Moreover, the expression of the equivalent material parameters of the ultrasonic critical refracted longitudinal wave propagation layer with stress variation is derived. An ultrasonic acoustic time difference model considering changes in contact surface material parameters is constructed based on the principle of acoustic elasticity of ultrasound. Furthermore, a critical refractive detection model for longitudinal wave’s tangential contact stress is established based on equivalent medium theory. Experimental specimens and stress detection plans are designed, and the tangential contact stress of the specimens is measured based on the division of surface grids. The equivalent stress value of each node is calculated based on the von Mises stress by measuring the stress in the X/Y direction. In addition, a shear stress distribution cloud map of the contact surface is drawn. Finally, the accuracy of the detection results is confirmed by combining theory, simulation, and experimental methods. The proposed tangential contact stress detection method based on critical refractive longitudinal waves is significant for low-stress assemblies.

Effect of Blade Thickness on Hemodynamics and Hemolysis: A Case Study of Pediatric Centrifugal Blood Pumps.

Blood pumps have become popular whether for use as an implantable ventricular assist device or as extracorporeal membrane oxygenation. The quality of these pumps is assessed according to their ability to reduce the risk of blood damage thanks to an optimal choice of their geometric and operating properties. Lack of the research focused on the geometrical optimization of impellers has prompted this study. This study evaluated a computational and experimental analysis comparing the hemolytic performance of three centrifugal pumps. For this purpose, methods of Eulerian and Lagrangian are respectively used for hemodynamic and hemocompatibility investigations. Referring to the pediatric demands, these pumps function under clinically applicable pressure-flow conditions: 1 l/min of blood flow and a pressure differential of 60 mm Hg. These three pumps all use the same volute, but their impellers differ in terms of blade thickness. The objective is to examine how surface area affects the generation of hemolysis. In silico simulations were employed for both of the following tasks: first, identifying the distributions of velocities, pressures, and shear stresses; second, applying the Lagrangian approach to estimate the hemolysis index. Results showed the importance of the flow passage and the surface of the clearance on the hemocompatibility of the pumps. However, it was observed that there is not a linear effect of the blade thickness on the shear stress or index of hemolysis. Additionally, this work can provide information to develop an optimal design of a more hemocompatible blood pump.

Rolling Contact Fatigue Behaviors of 20CrNi2Mo Steel by a New Carbon and Nitrogen Composite Infiltration Process

ABSTRACTIn this paper, a new type of composite infiltration process was adopted for 20CrNi2Mo steel. Rolling contact fatigue (RCF) tests were carried out on the specimens treated with carburizing (C) and composite infiltration with carburizing and nitriding (C‐N). The results showed that after C and C‐N treatments were performed, the surface microhardness was increased by 78% and 114%, respectively, and the maximum CRS were −220 and −530 MPa. Moreover, the residual austenite volume fraction was controlled to approximately 10% for each treated sample. The fatigue limit of the C‐N sample was 11.3% higher than that of the C sample. The fatigue failure mechanisms are caused by the maximum shear stress distribution and surface roughness. The surface layer of the C‐N sample with higher hardness and more compressive residual stress inhibited the initiation of fatigue cracks, and the appropriate residual austenite in the carbon‐nitrogen infiltrated layer inhibited the propagation of fatigue cracks.

Capillary Orientation and Morphology Dictated Oscillatory Electro-magneto-imbibition of Viscoelastic Electrolytes.

We explore the intricate dynamics of imbibition by a viscoelastic electrolyte within an arbitrarily oriented, nonuniform microcapillary, while under the stimulus of external electromagnetic fields and internal electroviscous forces stemming from streaming potential. The microcapillary walls are envisaged to be tapered relative to each other, with the entire system inclined with respect to the horizontal plane. The rheological behavior of the electrolyte is characterized using the Phan-Thien-Tanner (PTT) model. To manipulate the imbibition dynamics, external transverse magnetic and electric fields are imposed. Incorporating all contributing forces, we obtain semianalytical formulations for the velocity and shear stress distributions. We identify distinct stages during the imbibition process: (i) initial, (ii) filling, (iii) oscillatory, and (iv) stagnation stages. Moreover, we scrutinize the impact of four pivotal parameters, namely, the Weissenberg number (Wi), the Hartmann number (Ha), the transverse electric to viscous force (EVF) number (S), and the electric Reynolds number (Ree), on the imbibition dynamics across different inclinations and taper angles. We also delineate the parameter space for these four parameters, identifying where the onset of oscillations occurs. Finally, through scaling analysis, we establish the existence of four distinct regimes corresponding to the aforementioned stages: (i) the linear regime, (ii) the Washburn regime, (iii) the oscillatory regime, and (iv) the equilibrium regime. Our findings are anticipated to enhance the understanding of capillary imbibition under such complex flow conditions and contribute significantly to the advancement of capillarity-driven microfluidic devices.

Evaluation of Wellbore Stability by Small Parameter Perturbation Nonlinear Elastoplastic Model

Abstract Wellbore instability is a frequent occurrence during drilling and a popular research topic among petroleum workers. Most of the previous studies simplified the hardening stage and ignored or classified it into the elastic stage. Engineering practice shows that the total stress–strain process of rock can more truly reflect the bearing and deformation characteristics of rock. This study establishes a total stress–strain constitutive model by combining the perturbation index equation with the linear elastic equation. Additionally, the physical model of rock around the well is presented using the total deformation theory for the plastic zone. The stress field of the rock surrounding the well is analyzed based on the physical model of the rock surrounding the well, taking into account the influence of rock strength and geostress state. The relationship between rock strength, geostress state, drilling fluid density, and plastic radius is given. The calculation method of drilling fluid density limit is also given. The practical application demonstrates that the stability of a borehole wall can be evaluated by analyzing the size and direction of the plastic radius, as well as the distribution of radial, tangential, and shear stress for various combinations of stress states and rock strengths. The maximum shear stress is always found in the softening zone, which is also the region where wellbore instability is most likely to happen. Therefore, the area within the softening radius is regarded as an unstable area, and the softening radius can be used to determine the range of wellbore instability.

The implantation of a left ventricular assist device causes changes in the aortic miRNome and proteome - an integrative analysis

Abstract Background Left ventricular assist devices (LVAD) have been widely used and accepted to treat patients with end-stage heart failure. LVAD non-physiological blood flow velocity, wall shear stress distribution, vorticity current intensity, and vorticity flow generation affect the pathophysiology of vascular changes in aortic tissue. Purpose In this study, we performed multi-omics-based analysis of the aorta to identify molecular markers that could clarify vascular remodeling during LVAD support. Methods Aortic specimens from 48 patients (pair matched samples N=96) were excised during implantation and explantation of LVAD. Small RNA-Seq screening using Next Generation Sequencing and proteomic profile using Data-Independent Acquisition mass spectroscopy were conducted. Experimental and computational approaches, proteomics and transcriptomics data, were integrated and bioinformatics analyses were performed. Results The principal component analysis of miRNome and permutational multivariate analysis of variance of proteomic profile clearly segregated samples before and after LVAD support. We identified a total of 113 differently expressed (DE) miRNAs (61 up-regulated; Padj<0.05 and log2 fold change>|0.5|) after long-term LVAD support. Proteomic analysis identified in total 93 protein significantly changed (47 increased; Padj<0.05 and log2 fold change>|0.5|). Correlation analysis identified strong association between 270 proteins and 66 DE-miRNAs (Padj<0.05 and correlation coefficient>|0.7|). Gene Set Enrichment Analysis revealed, that predicted target genes of DE-miRNAs were mainly engaged in axon guidance, regulation of actin cytoskeleton, endocytosis, and MAP signaling pathway (Padj<0.05). DE-proteins participated mainly in ECM-receptor interaction, focal adhesion, and platelet activation (Padj<0.05). Conclusion Our study presents a network-based method of integrating microRNAs and proteome data and reveals molecular signatures that reflects aortic vascular remodeling due to LVAD treatment.PCA of miRNA DESeq2PCA of protemic profile

Experimental and numerical study of a novel inbuilt helical ridge small-caliber graft for artery bypass surgery

Small-caliber (≤ 6 mm) vascular grafts are commonly used to treat vascular diseases, yet intimal hyperplasia at the distal end-to-side anastomosis remains a significant complication with long-term use. Helical flow has been shown to reduce the risk of cardiovascular complications effectively. Integrating helical flow through an inbuilt helical ridge in vascular grafts is intended to improve hemodynamic performance and mitigate issues such as flow-induced thrombosis and intimal hyperplasia. However, inadequate helical flow strength may limit its effectiveness. This study proposes a novel design for an inbuilt helical ridge in small-caliber grafts to achieve enhanced helical flow. Two novel small-caliber vascular grafts with variable-pitch helical ridges, incorporating both decreasing and increasing pitches, were designed. Their effectiveness was assessed through numerical simulations and in vitro experiments to evaluate their performance in arterial graft applications. The small-caliber vascular grafts incorporating variable-pitch helical ridges significantly improved helical flow structure and distribution, optimized wall shear stress distribution, and reduced platelet adhesion compared to conventional and constant-pitch helical ridge grafts. Among the various new designs, the small-caliber vascular graft featuring decreasing variable-pitch helical ridges has demonstrated better performance. This design is well-suited for small-caliber bypass surgeries, as it is effective in improving hemodynamic performance by improving helical flow into asymmetric structures and increasing helical flow density distribution.

Time-dependent simulation of blood flow through an abdominal aorta with iliac arteries.

Atherosclerosis is one of the important diseases of the circulatory system because atherosclerotic plaques cause significant disruption of blood flow. Therefore, it is very important to properly understand these processes and skillfully simulate blood flow. In our work, we consider blood flow through an abdominal aorta with iliac arteries, assuming that the right iliac artery is narrowed by an atherosclerotic lesion. Blood flow is simulated using the laminar, standard and standard models. The obtained results show that despite the use of identical initial conditions, the distribution of velocity flow and wall shear stress depends on the choice of flow simulation model. For the model, we obtain higher values of speed and wall shear stress on atherosclerotic plaque than in the other two models. The laminar and models predict larger areas where reverse blood flow occurs in the area behind the atherosclerotic lesion. This effect is associated with negative wall shear stress. These two models give very similar results. The results obtained by us, and those reported in the literature, indicate that model is the most suitable for blood flow analysis.

Shearmetry of Fluids with Tunable Rheology by Polarized Luminescence of Rare Earth-Doped Nanorods.

Shear stress plays a critical role in regulating physiological processes within microcirculatory systems. While particle imaging velocimetry is a standard technique for quantifying shear flow, uncertainty near boundaries and low resolution remain severe restrictions. Additionally, shear stress determination is particularly challenging in biofluids due to their significant non-Newtonian behaviors. The present study develops a shearmetry technique in physiological settings using a biomimetic fluid containing rare earth-doped luminescent nanorods acting in two roles. First, they are used as colloidal additives adjusting rheological properties in physiological media. Their anisotropic morphology and interparticle interaction synergistically induce a non-Newtonian shear-thinning effect emulating real biofluids. Second, they can probe shear stress due to the shear-induced alignment. The polarized luminescence of the nanorods allows for quantifying their orientational order parameter and thus correlated shear stress. Using scanning confocal microscopy, we demonstrate the tomographic mapping of the shear stress distribution in microfluidics. High shear stress is evident near the constriction and the cellular periphery, in which non-Newtonian effects can have a significant impact. This emerging shearmetry technique is promising for implementation in physiological and rheological environments of biofluids.

A Multichamber Pulsating-Flow Device With Optimized Spatial Shear Stress and Pressure for Endothelial Cell Testing.

Design and analysis are presented for a new device to test the response of endothelial cells to the simultaneous action of cyclic shear stresses and pressure fluctuations. The design consists of four pulsatile-flow chambers connected in series, where shear stress is identical in all four chambers and pressure amplitude decreases in successive chambers. Each flow chamber is bounded above and below by two parallel plates separated by a small gap. The design of the chamber planform must ensure that cells within the testing region experience spatially uniform time-periodic shear stress. For conditions typically encountered in applications, the viscous unsteady flow exhibits order-unity values of the associated Womersley number. The corresponding solution to the unsteady lubrication problem, with general nonsinusoidal flowrate, is formulated in terms of a stream function satisfying Laplace's equation, which can be integrated numerically to determine the spatial distribution of shear stresses for chambers of general planform. The results are used to optimize the design of a device with a hexagonal planform. Accompanying experiments using particle tracking velocimetry (PTV) in a fabricated chamber were conducted to validate theoretical predictions. Pressure readings indicate that intrachamber pressure variations associated with viscous pressure losses and acoustic fluctuations are relatively small, so that all cells in a given testing region experience nearly equal pressure forces.

Comparative biomechanical analysis of a conventional/novel hip prosthetic socket.

The aim of this study was to investigate and compare the biomechanical properties of the conventional and novel hip prosthetic socket by using the finite element and gait analysis. According to the CT scan model of the subject's residual limb, the bones, soft tissues, and the socket model were reconstructed in three dimensions by using inverse modeling. The distribution of normal and shear stresses at the residual limb-socket interface under the standing condition was investigated using the finite element method and verified by designing a pressure acquisition module system. The gait experiment compared and analyzed the conventional and novel sockets. The results show that the simulation results are consistent with the experimental data. The novel socket exhibited superior stress performance and gait outcomes compared to the conventional design. Our findings provide a research basis for evaluating the comfort of the hip prosthetic socket, optimizing and designing the structure of the socket of the hip.

Estimation of aerodynamic entrainment in developing wind-blown sand flow.

Understanding aerodynamic entrainment, a critical process in wind-blown sand dynamics, remains challenging due to the difficulty of isolating it from other mechanisms, such as impact entrainment. Aerodynamic entrainment initiates the movement of surface particles, influencing large-scale processes like sediment transport and dune formation. Previous studies focused on average aerodynamic shear stress to estimate entrainment, but the role of impulse events, which cause significant shear stress fluctuations, remains under-explored. We used 12 hot-film shear sensors to measure the spatiotemporal distribution of aerodynamic shear stress during wind-blown sand flow development. We identified impulse events exceeding the entrainment threshold and analyzed their intensity, classifying particle movement as rocking, rolling, or saltation. Results indicate that after a 2-m fetch, sediment mass flux stabilizes, with aerodynamic shear stress decreasing to 78% of the entrainment threshold. We identified key trends, including the stabilization of rocking events beyond x = 4.5 m and a significant decrease in saltation frequency, indicating fully developed wind-blown sand flow. Impulse characteristics stabilize at a greater distance (4.5 m) than sediment transport (2 m) because turbulent airflow evolves more slowly. Our findings show that impulse events significantly influence aerodynamic entrainment. These insights enhance understanding of sediment transport dynamics and improve modeling of sand dune movement.

Topology optimization of coronary artery stent considering structural and hemodynamic parameters

In the present study, the impact of geometric variables and structural features of stents on hemodynamic parameters is investigated. Intravascular stent implantation is a treatment method whose success largely depends on the geometric structure of the stent and its effect on hemodynamic parameters. Medical devices called stents are inserted into arteries to restore blood flow when an artery is blocked. In this research, an optimal stent was designed and its effect compared to the common commercial stent used for coronary arteries was investigated and compared. It has been found that the geometry of the stent has an effective impact on the wall shear stress in the stented artery. Therefore, in this article, the importance of stent structures in the treatment of the coronary artery disease is discussed. For this purpose, first, an optimal stent is created with the topology optimization technique to find the best structure in the stent design. Finally, the optimized stent is numerically verified with ANSYS software and compared with existing commercial stents, and then the prototype is fabricated using additive manufacturing techniques. Commercial software ABAQUS, SolidWorks, and ANSYS are used in this research. The results showed that in optimizing a square plate, a sample with a minimum residual volume limit equal to 10 and 7 % can be selected as the optimal state. The results indicate that the new design can improve the distribution of wall shear stresses to reduce the adverse hemodynamic changes. Therefore, the proposed stent geometric structure can help improve the treatment. Finally, the optimized stent along with a commercial stent was made with the 3D printing method.

A Field‐Based Estimation of the Variability of Particle Entrainment in Coarse‐Bed Rivers

AbstractThe determination of critical shear stresses is fundamental to bedload sediment transport prediction in gravel‐bed rivers. Due to the heterogeneous shape and arrangement of the individual clasts in a riverbed, critical shear stresses typically show a large spatial variability, which is not adequately captured by the reach‐averaged description followed in common studies. In this regard, there is a general paucity of field data on this spatial variability of the critical shear stress, largely due to the lack of a standardized measurement method. In an attempt to fill this gap, we propose a field‐based workflow to estimate the frequency distribution of dimensionless critical shear stress (also named critical Shields number), which is based on the measurement of a series of variables related to the position, orientation and resistance to motion of individual clasts in a gravel‐bed river, combined with a probabilistic approximation to drag and lift coefficients. Following this workflow, the patch‐scale variability of particle incipient‐motion conditions was determined in a gravel bar of the Upper Cinca River, Spain. The results are consistent with what is known about sediment entrainment in gravel‐bed rivers. We consider this method to have great potential to advance our understanding of particle initiation of motion in gravel‐bed rivers as it provides valuable systematic field information.

Stress transfer paths and damage modes of layered coal-rock mass under static loading

In order to explore the distribution characteristics of nonlinear mechanical behavior and the tendency of damage and failure of deep in situ coal-rock mass, a layered composite thin plate coal-rock mass model is established based on thin plate theory and finite element method. The continuity of interlayer stress and displacement is maintained by transfer matrix function, and the maximum shear stress is calculated by Mohr-Coulomb strength criterion. The distribution characteristics of stress, displacement, energy and maximum shear stress of coal-rock mass under static load are obtained. The analysis results are as follows : ① The torsional stress concentration areas of τxz and τyz are formed on the boundary of coal-rock interface, and the principal stress concentration areas of σx, σy and σz are formed in the center and center of the boundary, and the shear stress distribution of τxy is formed on the diagonal line. ② The maximum shear stress of the long axis has a strengthening effect on the shear failure, and each layer forms a stress state of alternating tension-shear-compression-shear. It first destroys in the middle of the coal-rock interface and boundary, and then destroys along the long side and short side. ③ The coal-rock mass presents a ′ X ′ -type shear zone along the radial and axial. The shear failure occurs first, followed by the principal stress compression failure. The cracks are preferentially developed in the direction perpendicular to the minimum principal stress, and the stepped ′ V ′ -shaped failure characteristics are formed under the action of shear and tensile stress.

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.

Exploring hemodynamic mechanisms and re-intervention strategies for partial false lumen thrombosis in Stanford type B aortic dissection after thoracic aortic endovascular repair

ObjectivesFalse lumen (FL) thrombosis status for Stanford type B aortic dissection (TBAD) after thoracic endovascular aortic repair (TEVAR) is critical for evaluating aortic remodeling and long-term prognosis. This study aimed to monitor the morphology evolution of partial FL thrombosis (PFLT) and its hemodynamic conditions through an innovative approach, providing a re-intervention strategy from both morphologic and hemodynamic perspectives. MethodsThree-dimensional geometries are extracted from a five-year follow-up of CTA images for TBAD after TEVAR. The morphology and hemodynamics of PFLT are comprehensively analyzed based on patient-specific reconstructions and computational fluid dynamics (CFD). The impact of various strategies treating risk factors of PFLT, including proximal entry closure, left renal artery stenting, or accessory renal artery embolism on hemodynamics is assessed. ResultsThe introduced morphologic approaches appropriately reflected the evolution of PFLT. Gradual dilation of FL (surface area from 82.63cm2 to 98.84cm2, volume from 45.12 mL to 63.40 mL, increase in distal tear (from 3.72 cm to 4.32 cm), and fluctuation of thrombosis-blood lumen boundary are observed. For further surgical preparation in the absence of unanimously recognized re-intervention indicators, velocity and wall shear stress distributions reveal different simulated re-interventions have distinctly suppressive effects on hemodynamic conditions within the PFLT, providing valuable insights for further surgical preparation. ConclusionsThe present study demonstrates a re-intervention strategy for PFLT in TBAD patients after TEVAR utilizing morphologic and hemodynamic analyses. Acknowledging the deterioration of PFLT may result in adverse long-term outcomes, this strategy might offer an alternative approach for clinical monitoring and management of related patients.

Investigations on rigid–flexible coupling multibody dynamics of 5 MW wind turbine

AbstractThe flexible system of wind turbines refers to the components such as blades, towers, and rotor shafts that are subjected to external forces such as wind loads, inertial forces, and gravity during operation, resulting in deformation and vibration. This paper proposes that dynamic response analysis of the flexible system, through the response data, put forward improvement measures to improve the stability. The flexible dynamic response of wind turbine was analyzed. The fluid dynamics and structural dynamics of wind turbine are analyzed by the finite element method, and the flow chart is combined to get the wind turbine velocity, pressure, shear stress, and vorticity distribution nephogram. The results provide a reference value for monitoring structural state dynamics parameters of large wind turbines. Wind power generation technology is relatively mature, and its proportion in the field of power generation is gradually increasing. Wind energy is inexhaustible and can occupy a place in the development and utilization of new energy for a long time. This study provides an important reference for determining the dynamic parameters of wind turbine operation and improves the stability and reliability of wind turbine operation. The results provide a reference value for monitoring structural state dynamics parameters of large wind turbines.

Numerical prediction of passive speed and performance for multistage pump without power drive in natural flow process

With the development of engineering applications and the increase in system complexity, some particular fields, such as liquid rocket engine turbopumps, aircraft engine fuel systems, and marine natural flow cooling systems, are increasingly focusing on the performance characteristics of pumps under natural flow conditions. The pump is in the form of resistance components under natural flow conditions without a power drive. The impeller undergoes passive rotation by the impact of inlet flow. Due to the specificity of its operating conditions and performance indicators, the pump's natural flow performance cannot be evaluated by regular methods. Therefore, this paper proposed a numerical prediction method for pump natural flow performance based on a coupled computational fluid dynamics coupled with six-degrees-of freedom model. The performance of a multistage pump with guide vanes was evaluated under different natural flow conditions, and the accuracy was verified by experimental measurements. The transient variation mode of pump performance parameters with time at the initial stage of natural flow impact was analyzed. The flow field's transient evolution characteristics and the wall shear stress variation during natural flow were investigated. It was found that the impeller's passive rotational speed increases linearly with the natural flow rate, while the hydraulic loss shows an exponentially increasing trend. Meanwhile, the natural flow loss coefficient shows an exponentially decreasing trend and gradually tends to a stable value. The high turbulent kinetic energy inside the impeller is mainly distributed in the flow separation region and large velocity gradients. The distribution of shear stresses is closely related to the flow behavior inside the pump and the geometrical features of the hydraulic components.

Precise analysis of the static bending response of functionally graded doubly curved shallow shells via an improved finite element shear model

Doubly curved shallow shells, common in aerospace and civil engineering, pose significant challenges in predicting bending responses due to their complex geometry and material properties. Therefore, this research focused on the development of an efficient eight-node quadrilateral isoparametric element model based on a new improved first-order shear deformation theory (IFSDT) to analyze the bending deflection and stresses distribution of Functionally Graded (FG) doubly curved shallow shells. The present IFSDT obviates the necessity of a shear correction factor, which has challenges in determining for FG doubly curved shallow shells, by adopting a simpler assumption about transverse shear stresses. This assumption guarantees that the model precisely predicts the parabolic shear stresses distribution throughout the thickness of the FG shell while also meeting the requirements for free traction conditions on the top and lower surfaces of the shell. In the present analysis, five distinct types of FG doubly curved shallow shells are modeled: flat plates, spherical shells, hyperbolic parabolic shells, cylindrical shells, and elliptical paraboloid shells. A power law is employed to describe the gradual changes in material properties through the thickness direction. Numerical results for displacements and stresses are obtained for various shell types, materials, power-law factors, radii of curvature, and boundary conditions under uniform and sinusoidal loads. Comprehensive comparison and convergence studies are conducted to assess the robustness and accuracy of the proposed numerical model. This study also contributes new numerical results that are valuable for future research. Ultimately, the proposed numerical model offers a robust and straightforward tool for engineers and researchers engaged in the design and analysis of complex shell structures.