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This paper is focused on a new structural type - sandwich shell, which includes inner and outer shells connected by hoop connectors to achieve composite action; and a functional layer in the middle. Considering that the hoop connectors are not completely rigid, there will be limited slip between the inner and outer shells, which will lead to partial Degree of Composite Action (DCA). Due to the existence of the hoop connectors and shear lag effect, the stress distribution along the width direction of the shell is uneven, which can be described by effective width. Considering all these factors, this paper first develops an analytical model for sandwich shells with different configurations of connectors; and uses finite element analysis results to verify the analytical model. Next, a parametric study is conducted using the analytical model to study the effects of material strength, the ratio of the thickness of the functional layer to the thickness of the single layer shell, and the ratio of the arc length to the width of the sandwich shell on the effective width. It is found that DCA can significantly affect the stress and strain distributions of the sandwich shell. The effective width for 100% DCA can be used as a conservative value to represent those of other DCAs. Finally, a simplified calculation formula, which can be used in practical design, is derived based on the effective width for 100% DCA. [ABSTRACT FROM AUTHOR]

In recent years, reinforced thermoplastic composite pipe (RTP) is widely sought after because of its high strength and corrosion resistance. The development of a connector that is easy to install and highly reliable is essential for the successful application of RTP. In this paper, the mechanical properties of a butt-welding armoured joint between composite pipes were investigated by theoretical calculation method and finite element method. A plane strain model was established to study the mechanical response of the joint under internal pressure. In order to verify the theoretical results, a finite element model was established to analyse the stress distribution of the joint. Moreover, the finite element results are in good agreement with the theoretical results. The research of this paper provides a valuable reference for the engineering application of the joint in the pipeline system. [ABSTRACT FROM AUTHOR]

This paper introduces a highly efficient computational approach using the extended finite element method to model three-dimensional mechanics of holes and voids. The defect is encapsulated within a single element with a tailored exponential enrichment function that captures the behavior near the discontinuity boundary and can account for the pressure acting on the void's surface through an equivalent nodal force vector. The method's results were compared against analytical solutions and conventional finite element method results for problems involving single and multiple holes. The comparison demonstrated that the method provides accurate stress concentration estimates while adhering to computational constraints. [ABSTRACT FROM AUTHOR]

This paper aims to assess the mechanical characteristics of the orthotropic steel deck (OSD) in heavy-haul railway bridges. Taking the Dongting Lake Bridge as an example, to simulate the transfer effect of the track structure and get mechanical characteristics of the OSD under the service load, the refined segmental finite element model (FEM) of the OSD in a heavy-haul railway bridge was established. Moreover, the Chinese C80 heavy-haul train (the C80) was selected as the applied load to make the analysis results close to the actual situation. And then, the stress influence lines of critical components in OSD were analyzed. Notches at diaphragms of the OSD are more likely to produce stress concentration. Due to the dense distribution and high stiffness of the longitudinal ribs of OSD, the final load influence range of OSD is limited. Since the T-shaped longitudinal ribs (T-Ribs) are located under the position of each rail, and its stiffness is greater than the adjacent U-shaped longitudinal ribs (U-Ribs), so that the T-Ribs are important load-bearing components of the OSD in heavy-haul railway bridges. Furthermore, the influences of the stiffness ratio of T-Rib to U-Rib on the mechanical characteristics of the OSD were analyzed. [ABSTRACT FROM AUTHOR]

Deposition path patterns play an important role in controlling residual stresses and deformation in direct energy deposition-arc (DED-arc) process. In this paper, the effects of various path patterns on the evolution of the temperature history, residual stress distribution, and substrate deformations are investigated through experiments and finite element analysis. The predicted results of temperature fields and substrate deformations are verified experimentally by the infrared thermal imager and the laser profile scanner, respectively. It is found that the path patterns have significant effects on the stress distribution in the first few layers, and the minimum substrate deformation is obtained by the zigzag path along the short edge of the block. The proposed finite element method and measuring method are confirmed to be effective and feasible, providing valuable insight into the residual stresses and deformations control in the DED-arc process. [ABSTRACT FROM AUTHOR]

Although Friberg's theoretical analysis is frequently used to analyse the dowel bar-concrete interaction in jointed plain concrete pavement (JPCP) system, the compressive stress concentration at top and bottom of the dowel slot cannot be explained with this theory. In this paper, two modifications including the elastic deformation of concrete support and the stress distribution factor considering the sinusoidal contact stress distribution are proposed to improve the Friberg's theoretical analysis. Modifications are then validated against elastic finite element analysis (FEA) results in terms of the contact stress distribution, the maximum compressive stress as well as the range of compression zone. To further investigate the maximum compressive stress at the joint surface, relevant parameters including the dowel bar diameter, the modulus of elasticity of concrete as well as the joint width are studied through elastic finite element analysis (FEA). Apart from proposing referenced moduli of dowel support, a close relationship between the modified modulus of dowel support and dowel bar diameter is also found and verified. Finally, differences between the Friberg's theoretical analysis and the modified method are summarised in a flow chart at the end of the paper. [ABSTRACT FROM AUTHOR]

Repeated wet–dry cycle exposure to seawater during ballasting processes hastens the surface corrosion rate. Moreover, the larger volumetric changes of corroded ballast tanks generate lower pitting severity. This paper models the pitting severity of corroded ballast tanks of varying roughness and volumes. Seven rectangular finite elements models with Gaussian rough surfaces are examined. The surface roughness modelling is analyzed with correlation among corrosion-statistical parameters at various corroded specimen volume changes. Additionally, the paper elaborates the severity of pitting corrosion characteristics using the pitting factor and the relationship between the maximum and average pit depth. The pitting severity – volumetric changes scenario investigates the model's stress distribution, showing that the greater change in volume and lower pitting severity tend to have a lower stress distribution, which is randomly concentrated on the larger area. Comparison of the theoretical results with physical test data using 3D laser scans indicates a close match. [ABSTRACT FROM AUTHOR]

Since ancient times, pipeline has been widely used in human production and life. As the most critical link in the pipeline network, the reliability of joints greatly affects the piping system. Therefore, the research on joints is very necessary and meaningful, especially for the joints of composite pipelines. In this paper, an electric fusion joint was designed for perforated steel pipe reinforced thermoplastic composite pipe. Firstly, the key parameters of the joint were determined by the median diameter formula in the elastic failure theory. Secondly, the finite element model of the joint and the composite pipe was established. The stress distribution of the joint under the limit internal pressure was analysed by the finite element method and the correctness of the theoretical calculation was verified. Finally, the influence of structural parameters on the strength of the joint are revealed. [ABSTRACT FROM AUTHOR]

The paper presents the analysis of birdstrikes using SPH bird impacts model, 4 lb and 8 lb, on a small bay of a leading edge of an aircraft. Theoretical and numerical investigations were dedicated to three different configurations chosen for defining the leading edge's layups: a sheet metal with a thickness of 2.54 mm, a composite FML configuration with a thickness of 1.4 mm, and a sandwich-FML flexcore configuration that consists of an outboard skin in composite FML, a honeycomb core and an inboard metallic skin, with a total thickness of 8.05 mm. The paper presents a methodology, based on the use of analytical finite element modelling and analysis, to certify an aircraft in full compliance with the birdstrike requirement, using the nonlinear finite element code LS-Dyna. The results, including the displacements, stress distribution, damage predictions and the entire impact process during the birdstrike, were obtained from the simulations for each configuration. In order to validate the bird impacts model, firstly, the birdstrike simulation was carried out on a rigid plate and was referred to a selected experimental result, then, these validated results were extended to investigate 4 lb and 8 lb birdstrikes on three different bay's layups. These obtained numerical results on the leading edge were validated through an experimental result. The parametric studies were carried out by characterizing the material for the aircraft leading edge, and the results can be utilised in the initial designing phase as well as for the 'certification by analysis' of the aeronautical structures. [ABSTRACT FROM AUTHOR]

In the present study, the fracture analysis of functionally graded materials (FGMs) of various material distributions with discontinuities (crack and inclusion) under localized loadings is carried out by the extended finite element method (XFEM). In the present work, the effect of discontinuities and material distributions like exponential, power law, Mori–Tanaka, and sigmoidal in FGMs is also presented, where the different material distributions are compared for the fracture analysis of FGM plates and beams. This present work will be helpful for the researchers to understand the effect of different material distributions on FGMs under localized ladings. The XFEM-based numerical analysis is carried out to find stress intensity factors (SIFs) and stress distributions. The MATLAB code is developed for this analysis and is validated with a previously published research paper. [ABSTRACT FROM AUTHOR]

Present study develops the experimental and finite element analysis of an auxetic piezoelectric energy harvester consisting of a cantilever, auxetic substrate, and piezoelectric layer. Firstly, five auxetic models with 1, 4, 9, 16, and 25 honeycomb auxetic cells are presented. Harvested power and stress distribution of the piezoelectric layer for these models are compared with plain piezoelectric energy harvester. All the analysis has been performed using the experimental tests and finite element method. Mesh size sensitivity analysis of the finite element model is presented, and it is verified by previous experimental studies. The model with 25 auxetic cells harvests more power than other models. Furthermore, comparing stress distribution on the piezoelectric layer of these models indicates that increasing the number of auxetic cells leads to increasing the average stress on the piezoelectric layer. The present investigation illustrates that harvested power of an auxetic energy harvester in resonant frequency could improve to twenty times more than a plain harvester. Besides, the new auxetic model with trapezoidal geometry is presented in the present paper. Utilizing this model as the substrate in a piezoelectric energy harvester leads to increasing the efficiency of the energy harvester by 82.5%. The damping ratio of the auxetic energy harvester has been measured by experimental investigation. Also, experimental analysis has been performed to find the optimum energy harvester circuit resistor. The density of the harvested power for the trapezoidal energy harvester with an optimum circuit resistor is 107% more than the rectangular energy harvester. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of stress developed in flex-gear (FG) cup with conventional strain wave generating (SWG) cam and split-cam SWG in strain wave gear/harmonic drive (HD), using initial load distribution by tooth pairs as a boundary condition in finite element method (FEM). The initial load distribution by tooth pairs is achieved with the assembly of ring gear (RG) and deformed FG before the application of any external load. A closed-form solution to the analytical method describes the exact initial load distribution by tooth pairs in the presence of secondary contacts. However, with spit-cam SWG the phenomenon of secondary contact is completely eradicated. Therefore, the load is distributed by contacting tooth pairs that lie only in the line of action and the tooth pair that lies along the major axis of split-cam SWG experiences maximum load compared to conventional SWG. The strain developed in FG cup based on the load distribution with both SWG cams obtained from FEM is verified with the experiment. The comparison shows a rise of 44 microns in circumferential strain around the major axis of deformed FG, when RG is assembled. This testifies the presence of initial load, which is distributed among all interfering tooth pairs before applying external load. [ABSTRACT FROM AUTHOR]

This paper aimed to investigate the biomechanical changes during the talus impact with the calcaneus at varying velocities. Various three-dimensional reconstruction software was utilized to construct a finite element model that consisted of the talus, calcaneus, and ligaments. The explicit dynamics method was used to explore the process of the talus impacting on the calcaneus. The velocity of impact was altered from 5 m/s to 10 m/s with a 1 m/s interval. Stress readings were collected from the posterior, intermediate, and anterior subtalar articular (PSA, ISA, ASA), calcaneocubic articular (CA), Gissane Angle (GA), calcaneal base (BC), medial wall (MW), and lateral wall (LW) of the calcaneus. The changes in the amount and distribution of stress in the different regions of the calcaneus that varied with velocity were analysed. The model was validated through comparison with findings from the existing literature. During the process of impact between the talus and calcaneus, the stress in the PSA reached its peak first. Notably, stress was concentrated mainly in the PSA, ASA, MW, and LW of the calcaneus. At varying impact velocities of the talus, the mean maximum stress of the PSA, LW, CA, BA, and MW exhibited statistically significant differences (P values were 0.024, 0.004, <0.001, <0.001, and 0.001, respectively). However, the mean maximum stress of the ISA, ASA, and GA was not statistically significant (P values were 0.289, 0.213, and 0.087, respectively). In comparison with the velocity at 5 m/s, the mean maximum stress increases in each region of the calcaneus at a velocity of 10 m/s were as follows: PSA 73.81%, ISA 7.11%, ASA 63.57%, GA 89.10%, LW 140.16%, CA 140.58%, BC 137.67%, MW 135.99%. The regions of stress concentration were altered, and the magnitude and sequence of peak stress in the calcaneus also varied according to the velocity of the talus during impact. In conclusion, the velocity of the talus during impact had a significant influence on the magnitude and distribution of stress within the calcaneus, which was a crucial factor in the development of calcaneal fractures. It was possible that the magnitude and sequence of stress peaks played a vital role in determining the emergence of fracture patterns. [ABSTRACT FROM AUTHOR]

To explore the dynamic crack propagation behaviour in the fracture zone and the damage characteristics of the rock mass around the blasthole during eccentric uncoupled blasting of a deep-level rock mass, theoretical analysis, model experiments and numerical simulation studies have been described in this paper. Firstly, the stress state of the crack and the stress distribution state and failure mechanism of the rock mass around the blasthole under the influence of the in-situ stress, and the pressure distribution of blast shock wave on the blasthole were analysed. Secondly, with the help of a new digital laser caustics experimental system, the eccentric uncoupled blasting model experiment under the action of the in-situ stress was carried out. The fractal damage theory is used to quantitatively evaluate the damage degree of the rock mass in different areas around the blasthole, and the blast-induced crack propagation mechanical behaviour characteristics in the fracture zone are analyzed from the perspective of dynamics. Then, based on the LS-DYNA software, a numerical simulation study was conducted on the eccentric blasting of deep rock mass. Finally, some discussions and suggestions are provided for the analysis of blasting mechanisms in a deep-level rock mass. [ABSTRACT FROM AUTHOR]

In this paper, a new approach for measurement of the fracture toughness of concrete using the edge cracked semi-cylinder disk (ECSD) specimens has been rendered. The critical stress intensity factor (fracture toughness) of concretes was determined by using the edge cracked semi-cylinder disk (ECSCD) type specimens. The normalized Mode I stress intensity factor of concrete was measured and estimated through a new formula. The versatile finite element method (FEM) was used to derive this appropriate formula and the Mode I fracture toughness of the specimens determined with a reasonable accuracy. In the laboratory, the notched Brazilian disks (NBD) were tested to evaluate the accuracy of the ECSCD method. A discrete element analysis of the ECSCD tests was also carried out to numerically simulate these experiments and validate the accuracy of the fracture toughness values. Finally, very good agreements gained by comparing the crack extension patterns obtained from the experimental tests with the numerical simulations' results. However, the toughness values obtained through ECSCD experiments were lower than those measured from the NBD tests. This is due to the smooth distribution of tensile stress around the notch in the ECSCD concrete specimens. [ABSTRACT FROM AUTHOR]

Scarf patching is the preferred technique for repairing physically damaged aircraft composite structures. The commonly used patch design is a circular conical frustum with a 3°optimized scarf angle. However, for this repair patch design the volume of material removed from the repaired composite panel can be quite large. This paper examines the effects of the different parameters on the stress state in the patch adhesive, such as ply orientation, stacking sequence, ply thickness and scarf angle. It explores an adaptive design of the repair patch for orthotropic materials and composite laminates, using 3D Finite Element Analysis. The design optimization approach is based on the evaluation of a Failure Criterion Index (FCI) and the minimization of its Relative Standard Deviation (RSD). An optimized scarf shape, which takes into account biaxial tensile loading conditions, fiber direction, and stacking sequence, is an elliptical conical frustum that induces a variable scarf angle along the sweeping angle. This design showed that less parent material is removed than that of the circular shape (decreased by up to 41%) and that the shear stress dispersion in the adhesive was significantly reduced (RSD decreased by up to 18%). The optimization method and the improved shapes are presented and discussed with respect to the influencing parameters. [ABSTRACT FROM AUTHOR]

Field evidence revealed that buried cast iron water pipes can deteriorate through large localized corrosion patches with lengths greater than 1 m, formed by a cluster of small pits. This study investigated the effect of large corrosion patches on the performance of large-diameter cast iron pipes. Although large corrosion patches are highly irregular in nature, they were idealized as semi-ellipsoids. To validate the approximation of corrosion patch geometries with semi-ellipsoids, comparison of finite element models of scanned corroded pipe geometries with the approximated semi-ellipsoidal patches on the same pipes were conducted. Following this validation, parametric studies were performed, which covered a wide range of the pipe and patch dimensions. Based on the finite element analysis, an equation for stress concentration factors was derived and is presented in this paper. This development will significantly assist the pipe engineers and asset managers in the condition assessment of corroded cast iron pipelines. [ABSTRACT FROM AUTHOR]

In this paper, a numerical axisymmetric elastic stress wave propagation analysis of the 2D-FGM hollow thick finite cylinder has been performed. The new accurate material distribution model based on Mori-Tanaka scheme and third-order transition function for 2D-FGMs has been implemented in the graded finite element method with higher-order quadrilateral elements. A non-uniform impulsive pressure has been applied on the one-third of the top inner cylinder wall. Consequently, different wave velocities and reflections from the boundaries have been observed due to the graded distribution of material along with two directions. Moreover, the effects of two-dimensional material property distributions on the stress wave propagations and displacements through the cylindrical wall at different locations have been studied systematically. Normalized effective stresses based on von-Mises criteria has been performed in comparison with the internal impulsive pressure amplitude to provide a measure of the cylinder wall response to the mechanical impact loading, the effective stresses are nearly 2.5 times the internal pressure loading amplitude, closed to the impact location. According to the results, 2D material property gradations has effected the stresses significantly. Alternatively, desired stress values can be achieved through optimal design and appropriate choice of property distribution. [ABSTRACT FROM AUTHOR]

Due to improvements in diesel engine power and performance, the piston in the combustion chamber is subjected increasingly higher thermal and mechanical loads. The cyclic changes in thermal and mechanical stresses seriously affect the piston fatigue life. Therefore, it is necessary to analyze the strength of the piston in the design process. In this paper, the finite element analysis of piston under thermal, mechanical and thermo-mechanical loads coupling is carried out by using the ANSYS software. By analyzing the heat and force distributions on the piston, the stress and strain distributions on the piston can be obtained, so as to determine the maximum stress concentration areas and check whether the piston strength meets the requirements. Results indicate that the highest temperature on the piston appears at the top of the combustion chamber bulge, where the deformations of the piston and combustion chamber are the most serious. There is a large stress concentration in the contact between the piston pin seat, the piston pin hole and the piston. The minimum number of piston cycles is 1.2×106 times, which meets the piston cycle number from starting, running, and to stopping process. Thus the strength of the diesel engine piston meets the requirements. [ABSTRACT FROM AUTHOR]

This paper aims to study the effect of stress corrosion on the electrochemical behavior and corrosion mechanism of epoxy zinc-rich coating/steel substrate. The electrochemical impedance spectroscopy (EIS) was applied to characterize the corrosion behavior of the system under different stress conditions (σ1 = 0MPa; σ2 = 120MPa; σ3 = 180MPa and σ4 = 240 MPa), and appropriate equivalent circuits were established. Additionally, the von Mises stress distribution and potential distribution around the pitting pit at the coating-substrate interface were quantified by means of finite element analysis. The approach used different tensile strains and the depths of the pitting pit to relate the corrosion current density and corrosion rate to the corrosion process. The EIS results demonstrate that, given the same time, the failure time of the epoxy zinc-rich coating/steel substrate system with 240 MPa is shortened by 27.8% compared to the system without stress. Meanwhile, the finite element model confirms that the uneven potential distribution around the pitting pit is responsible for coating failure. In-depth profile of the corrosion rate shows an increasing trend over the distance from the opening. Then this local corrosion acceleration will cause further stress concentration, which in turn accelerates the corrosion process of the system. [ABSTRACT FROM AUTHOR]

This paper discussed the size of 3 D-printed personalized titanium plates that can gain maximum stability of mandibular fracture and minimize stress shielding through finite element analysis. A 3 D virtual model of mandible with mandibular angle fracture was created from the CT data of patient. 3 D-printed personalized titanium plates varying in length and thickness were designed, and finite element analysis was performed under different loading conditions and fracture healing periods. After that, the stress distribution and deformation of the mandible with gonial fracture could be observed, and the stress shielding rate could be obtained. Finally, SPSS21.0 was used for statistical analysis. The results of finite element analysis indicated that as the thickness of titanium plates and the healing time decreased, the maximum displacement increased, under a certain condition in which the pore size, the width, the hole distance and the bridge spacing were 2.0 mm, 4.0 mm, 6.0 mm, 12.0 mm, respectively. What's more, in this condition, the thicker the titanium plate and the shorter the healing time were, the higher the stress shielding was at central occlusion. When the thickness of the personalized 3 D-printed titanium plate was 1.0 mm, the maximum displacement tended to be stable and the stress shielding was minimized. It can not only improve the bone stability after tension band fixation, but also minimize the stress shielding, which is expected to expand the indications of tension band fixation. [ABSTRACT FROM AUTHOR]

This paper proposes a novel method to impart intelligence to metal parts using additive manufacturing. A sensor-embedded metal bracket is prototyped via a metal powder bed fusion process to recognise partial screw loosening or total screw missing or identify the source of vibration with the assistance of artificial intelligence (AI). The digital metal bracket can recognise subtle changes in the screw fixation state with 90% accuracy and identify unknown sources of vibration with 84% accuracy. The von Mises stress distribution in the prototyped metal bracket is evaluated using a finite element analysis, which is learned by AI to match the real-time deformation analysis of the metal bracket in augmented reality. The proposed prototype can contribute to hyper-connectivity for developing next-generation metal-based mechanical components. [ABSTRACT FROM AUTHOR]

Composite lap joints have been extensively used due to their excellent properties and the demand for light structures. However, composites exhibit weak mechanical properties in their thickness, which may cause failure in composite lap joints. Various reinforcement methods that delay fracture by dispersing stress concentration have been discussed to overcome this problem, such as z-pinning and conventional stitching. After several studies and publications, the I-Fiber stitching process is a promising technology that combines the advantages of both z-pinning and the conventional stitching process. In this paper, the reinforcing effect of the I-Fiber stitching process was verified by fabricating composite single-lap joint specimens with different thicknesses, number of I-Fibers, and stitching angles to evaluate the lap shear strengths. Experimental results showed an improvement of up to 52.1% using the I-Fiber stitched process compared with the unstitched specimens. In addition, a better ratio of improvement in the reinforcement was observed with thinner composite adherends, and a higher failure load was achieved using a 45° stitching angle compared with 0°. Finally, through finite element analysis, it was possible to study the behavior and predict the interface failure of the single-lap joint. The results obtained showed good agreement with the experimental data and supported the failure mechanism's understanding using the I-Fiber stitching process. [ABSTRACT FROM AUTHOR]

Traditional jointed plain concrete pavement (JPCP) systems cannot be reused after grouting fast-setting materials in the dowel slot. To achieve demountability, a removable dowel bar connection system is proposed in this paper. The severe stress concentration occurring in JPCP systems is mitigated by applying a stainless steel ring at the pavement joint surface. In the monotonic loading tests, different stainless steel ring thicknesses, lengths and the stainless steel tube thicknesses were considered. The effect of the stainless steel ring on the structural performance of the removable dowel bar connection system was studied in terms of the failure mode, the deflection response, ductility and the strain distribution and development. Besides, after being validated against experimental test results, the developed finite element model was used to conduct the extended parametric analysis, in which a close relationship was found between the ultimate load and the stainless steel ring length. To prevent the localised crushing failure, the maximum compressive stress at the joint surface was compared with the allowable bearing stress under service load. By using FEA data, an empirical equation was finally proposed to predict the ultimate loads of specimens with the proposed connection system. [ABSTRACT FROM AUTHOR]

Because of its characteristics of good rigidity and strong ant-vibration, heavy-duty welding turning tools are widely applied in the rough machining of water chamber heads. However, welding residual stress is induced around the welding seam of the tool. During the heavy-duty machining, cracks easily occur due to an influence of impacts, high-temperature and thermal-mechanical loading, which causes tools failure. In this paper, ANSYS finite element model of heavy-duty cutting tools is established based on thermal elastic-plastic theory in order to analyze thermal stress field distribution in welding process. Secondly, actual welding residual stress distribution is obtained by the nano indentation experiment, verifying that the model can effectively analyze the stress and strain distribution. The welding tool failure mechanism is explored further. Finally, vibration aging and ultrasonic impact treatment methods are adopted to reduce welding residual stress of heavy-duty cutting tools. Two methods are compared for the influence of welding residual stress. Through the above research, finite element model can exactly reflect the welding residual stress distribution. The ultrasonic impact treatment is better than vibration aging treatment to reduce the welding residual stress and then extend their service life. [ABSTRACT FROM AUTHOR]

In the present work, a fully coupled thermo-mechanical analysis is presented to obtain the desired bend angle in the sheet made of AM30 magnesium alloy. The finite element method (FEM) based software ABAQUS 6.10 is employed to estimate the temperature, stress and strain distribution with time for different laser bending process parameters. An FEM proposed model is validated with the experimental results. Some parametric study has been performed to see the influence of laser process parameters on AM30 alloy. Single and multi-passes laser line heating is employed, and observed that the bend angle achieved in multi-passes is approximately 430% higher than the single pass. Hence, the results presented in this paper can be used to assess the applicability of AM30 magnesium alloy in laser-based forming industries. [ABSTRACT FROM AUTHOR]

Lining is gaining acceptance in underground excavations because of its reinforcing and protecting capacities. The purpose of this paper was to derive an analytic expression based on the complex variable method to describe the behaviour of a tunnel with a liner of finite thickness. The stress functions have been expressed as Laurent series where the infinite undetermined coefficients are obtained using force and displacement boundary conditions at the inner face, liner–rock interface and far-field boundaries. The finite element method has been used to verify the proposed solution; a good agreement has been obtained both in the surrounding rock mass and within the liner. In addition, based on the verified solution, the liner effect on the critical position of the interface has been investigated by applying Mohr-Coulomb's failure criterion. A detailed parametric study shows that the relative liner thickness, relative stiffness and lateral stress coefficient have a great influence on the failure position, while the internal friction angle of the rock has a slight effect on the results. The proposed analytical solution is not restricted to the liner thickness, and the stress distribution within the liner is obtained accordingly; the solution can be generalised to other applications such as backfill analysis by setting the liner thickness equal to the radius of the opening. [ABSTRACT FROM AUTHOR]

This paper puts forward a new method to predict the bearing strength of single bolt joint based on characteristic length method (CLM) and progressive damage model (PDM). Instead of performing the whole campaign of PDM-based CLM on whole structure of joint, the characteristic length and stress distribution of the sub-laminates obtained by dividing the original laminate are used. Stress gradient along the thickness, which is caused by the secondary bending effect of single-lap joint, can be taken into consideration. 3D progressive damage models are established for obtaining the bearing response of sub-laminate with emphasis on fiber kinking theory, where an interpolation algorithm is adopted to find the kinking plane and corresponding kinking angle. Both numerical models and experiments are utilized to verify our scripts of new method. It is concluded that the bending effect can be successfully considered and the proposed method shows advantages for the structural design of mechanically joints. A new method is put forward by dividing the original laminate into sub-laminates to account for secondary bending effect. A progressive damage model based characteristic length method is employed to predict failure of each sub-laminate. The kink band theory is used for the interpretation of the mechanism of fiber compressive damage and a zero-thickness cohesive method is used for interlaminar damage. An interpolation algorithm is adopted to find the kinking plane while a graphic method is used to obtain the kinking angle. [ABSTRACT FROM AUTHOR]

As people pay more attention to the aesthetics of teeth, the adhesion of brackets in the orthodontic process received a wider application in recent years. In this paper, experiments and finite element method (FEM) were combined to study the mechanical behaviour of adhesively bonded orthodontic brackets, as well as fracture performance in the adhesive layer. The tensile, shear and mode I/II fracture testing were carried out first to determine reliable parameters of the adhesive for numerical simulation. Quasi-static tensile-shear loading was applied to determine the failure strength of bracket bonded with enamel. Bi-linear cohesive element was inserted to simulate the failure process of the adhesive layer. The failure strength obtained by experiments and FEM were 8.25 MPa and 9.15 MPa, respectively, with deviation of 9.8%. The load–displacement curves obtained by simulation and experiment were in acceptable agreement. The damage propagation and stress distribution in the adhesive layer and enamel during tensile-shear loading were then analysed. The proposed FE method can be used to predict the bonding strength of brackets, and thus provide reliable reference for the force applied during clinical treatment and possible fracture mechanism during daily use of orthodontic brackets. [ABSTRACT FROM AUTHOR]

The question of the thickness and diameter report on the performance of the structures is approached in detail in this scientific work. This paper focuses on the stress-strain characteristics, geometry imperfections, damage and deformations that occur inside the materials structure properties. Finite element analysis and experimental results show that, as loading progressed, the strain distribution in the shaft lining structure became approximately uniform indicating the formation of a tied arch mechanism. Concrete strain distribution is nonlinear and non-conform to Bernoulli’s assumptions for strain and stress distribution; this nonlinearity is due to the shear deformations inside the structural element. The study can provide certain reference for practical engineering calculation. [ABSTRACT FROM AUTHOR]

In this paper, an incremental finite element model (IFEM) for the transient analysis of viscoelastic solids is developed. The viscoelastic constitutive response is modeled based on the hereditary integral. Two new incremental constitutive forms suitable for finite element implementation are derived; creep-based (CB) and relaxation-based (RB) and, as a consequent, the difficulties associated with the interconversion from the relaxation modulus to the creep compliance and vice versa are avoided. Creep compliance and relaxation modulus are, respectively, modeled using generalized Kelvin–Voigt model and generalized Wiechert's model. To check the validity, the computational procedure, semi-analytical solution is derived for simple viscoelastic cases using Laplace and inverse Laplace transform techniques. The obtained results from the computational procedure are compared with that obtained from the derived semi-analytical solution. To show the validity and applicability of the developed model, two different applications under different excitation patterns are presented. In each application, the time response for displacements and stresses, especially for the dynamic stress concentration factor for both elastic and viscoelastic analyses are investigated. Moreover, the dissipative recoverable nature of the viscoelastic solids under different loading-unloading excitation patterns is illustrated. [ABSTRACT FROM AUTHOR]

This paper presents an experimental and numerical model of carbon fiber reinforced polymer (CFRP) retrofitted concrete beams with and without intermediate notches, developed to predict the impact load, energy response, cracking pattern and interfacial stress distribution under drop-weight impact. Considering a drop-weight falling from different heights, a CFRP sheet was bonded to the bottom surface of the beam. The specimen's drop-weight impacts were established for retrofitted and un-retrofitted simply-supported notched concrete beams. A nonlinear finite element model was developed and calibrated to analyze the interfacial stress field, failure modes, cracking patterns and damage sequences. The results obtained numerically in terms of load-time, load-displacement and energy-time curves were compared to those given by the authors' experimental tests and also to those given in the literature. For un-retrofitted beams, the impact time was very short, with failure at the center of the beam. For notched beams, the impact load decreased as notch depth increased, owing to the local loss of rigidity at the center of the concrete beam. For the retrofitted beam, however, the impact time was quite long, with a very high impact load, because the beam was more resistant, with rebound. [ABSTRACT FROM AUTHOR]

Based on the theory of digital image processing, geometric vector transformation and the principle of automatic generation of finite element meshes, a finite element-discrete element analysis method for digital image of geotechnical engineering materials is proposed. Combining the digital image technology with the finite element-discrete element method (FDEM) coupling analysis method proposed by Munjiza, a FDEM analysis system is developed to characterize the real heterogeneity of rock mass, which provides a new way to model rock mass and study the fracture mechanism of rock mass from a meso-scopic point of view. With the help of digital image technology, the system obtains the real meso-structure of rock material from the image of rock section. With the help of mature mesh generation technology, it maps it to the FDEM computational grid, thus overcoming the shortcomings of the original FDEM in considering material heterogeneity. Using this system, the Brazilian disk splitting test is simulated numerically, and the real fracture process of granite under load is reproduced. And we examined how transparency and task type influence trustfulness, perceived quality of work during human-autonomous system interaction. The numerical simulation results show that the stress distribution of rock samples considering heterogeneity is asymmetric, and the micro-structure of rock has an important influence on the crack propagation and stress distribution in rock. [ABSTRACT FROM AUTHOR]

The aims of the study were to determine the effect of different types of endodontic sealers and the presence of a horizontal glass fiber post (HGFP) on the fracture resistance and fracture pattern of mesio-occluso-distal (MOD) restored upper premolars and to analyze the stress distribution. Sixty extracted upper premolars received root canal treatment (RCT) and a MOD cavity preparation. All MOD cavities were restored with the same composite resin (CR). The 60 teeth were divided randomly into 6 groups (n = 10); Group1= AH Plus sealer; Group 2= TotalFill BC sealer; Group 3= BioRoot RCS sealer; Group 4= AH plus sealer + HGFP; Group 5= TotalFill BC sealer + HGFP; and, Group 6= Bio Root RCS sealer + HGFP. All specimens were thermocycled and subjected to cyclic loading. Next, the specimens were subjected to a static load using a universal testing machine. Data were analyzed using two-way ANOVA. Two micro-CTs of the same upper premolar, one without the HGFP and later one with HGFP inserted were made and used to create two finite element (FE) models. For the fracture resistance, two-way ANOVA revealed significant differences for the effect of HGFP (p = 0.029), but no differences for the effect of root canal sealer type (p = 0.561). The HGFP groups showed higher restorable fracture compared to groups without HGFP (p = 0.013). Finite element analysis showed that the inclusion of HGFP reduces stress concentration at the occlusal interface and cervical region. Therefore, it can be concluded that HGFP significantly increased the fracture resistance of endodontically treated upper premolars with MOD cavities and reduced the risk for non-restorable fractures. The FE analysis supports the mechanical test results. [ABSTRACT FROM AUTHOR]

This investigation delves into the dynamics of stress distribution during particle impacts on Incisor teeth, revealing the significant roles of particle size, impact angle, and standoff distance. An explicit dynamics study highlights a crucial revelation: optimal outcomes are achieved with a particle size of 250 µm, a 5 mm standoff distance, and an 80-degree impact angle, resulting in maximal stress manifestation. The analysis highlights a direct relationship between particle size and stress distribution, where larger particles amplify stress levels, emphasizing its pivotal role in determining stress distribution patterns. Additionally, an investigation of the Signal-to-Noise (SN) ratio reaffirms this trend, validating the direct correlation between stress distribution magnitude and abrasive particle size. Interestingly, variations in standoff distance and impact angle exhibit relatively minor effects. The ANOVA further strengthens these findings, with lower p-values for particle size and impact angle, highlighting their substantial contributions to stress distribution. Exploring interactions uncovers significant relationships between abrasive particle size and impact angle, as well as impact angle and standoff distance, with implications for stress distribution optimization. This study offers a broad investigation of the effects of abrasive particle size, standoff distance, and handle angulation on stress distribution during air abrasive procedures in dentistry. Through advanced computational modelling techniques, we interpret the complex interactions between these parameters and their impact on tooth surface integrity. The research findings not only provide valuable insights into optimizing procedure parameters for enhanced safety and efficacy but also contribute to the advancement of knowledge in the field of dental materials and techniques. [ABSTRACT FROM AUTHOR]

This study investigates the vibration characteristics of spinning annular disks with various boundary conditions aiming to investigate the effect of radius ratio parameter and the rotation speed on natural frequencies of a spinning disk analytically for nine different types of boundary conditions. The stress distributions on the disks are obtained for all boundary conditions. The Galerkin method is employed with polynomial functions as approximate displacement functions. Analytical results are presented and compared to the results of the finite element analyses as well as experimental ones. [ABSTRACT FROM AUTHOR]

One of the effects of creep phenomena in structures is stress relaxation. Owing to this effect, the stiffness of each point is inversely related to the stress at that point, which causes a stress redistribution, a reduction of the maximum stress, and an increment in the displacement field. By contrast, for structural optimization, it is a practical and challenging problem to consider the maximum stress as a failure criterion or objective function. In the present study, the stress relaxation effect was investigated in stress-based topology optimization. The so-called solid isotropic material with penalization method and a nonlinear finite element analysis are utilized for this purpose. The maximum von Mises stress and the total volume of the structure are selected as the objective function and constraint, respectively. The main novelty of this research is to find the optimized topology with the least maximum stress by developing and implementing a time-dependent adjoint method for sensitivity analysis. Implementing the calculated sensitivity for stress-based problems in a gradient-based optimization method, such as the optimality criteria, is quite challenging, and some numerical instabilities in the optimization process are addressed. Several examples are solved with and without considering the stress relaxation effect. The results reveal that the influence of stress relaxation in the reduction of stress concentration makes the optimized layout more similar to the optimized layout obtained by minimizing the compliance for the linear structures. [ABSTRACT FROM AUTHOR]

Localized damage may occur due to the fact that laminated bamboo lumber (LBL) has a lower compressive strength perpendicular to the grain direction than it does parallel to the grain. In this study, the transverse compressive performance of LBL under entire-surface compression and local-surface compression is investigated. Load–displacement curves, stress–strain relationship, detailed failure modes, and basic mechanical properties are obtained. The results show that despite the compressive strength and elastic modulus being nearly the same in the two transverse orientations, the failure patterns are distinct due to the layer structure. Ramberg-Osgood relation is utilized to fit the stress–strain curves. Proportional limit strength is determined indicating that specimens compressed locally have a greater load-bearing capability. Based on the finite element analysis and theoretical study, the mechanism of the enhancement in proportional limit strength is revealed. Equations for determining the bearing load of a specimen under local compression in the elastic stage are derived from the simulation data and logit model, considering the contact length and geometric size of the specimen. Additionally, parametric tests are conducted to determine the effect of bearing shape, bearing area, and loading mode on the stress distribution and bearing capacity. [ABSTRACT FROM AUTHOR]

When a penstock serves a water supply purpose for multiple hydrogenerators in a hydroelectric power plant (HPP), a bifurcation structure should be installed between the main pipe and the branch pipes. This study focuses on a rib-strengthened steel bifurcation structure (RSSBS) with an emphasis on its hydraulic load-bearing mechanism. The finite element method is used with the contact and material non-linearities considered. The numerical simulation results agree reasonably well with in-situ measured data. Our research has underlined the critical role of the crescent-shaped rib (CSR) in lessening the stress-concentration at the bifurcation. The CSR is found to separate from the surrounding concrete under the internal water pressure (IWP), thus causing less IWP to be transmitted to the concrete. Despite the fact that the CSR is not in tension-stress-only status, however, the tensile-stress level is well within an acceptable range. In this context, the CSR should not necessarily be in tension-stress-only status, which is recognized as an ideal stress state in the conventional design philosophy. The findings also suggest that the importance of the concrete should not be stressed too much in the structural design of RSSBSs considering its backfilling role. The role of the crescent-shaped rib in strengthening local stiffness is underlined. The rib is found to separate from the concrete under the internal water pressure. The simulation results agree reasonably well with in-situ measured data. [ABSTRACT FROM AUTHOR]

Bond and anchorage are the basis to conduct performance analysis on reinforced-concrete structures. The strain-hardening property makes the bond-slip behaviour of rebars in ultra-high-performance concrete (UHPC) different from that in ordinary concrete. This study investigates the anchorage performance of straight rebars in UHPC based on its material properties. First, the anchorage failure process is revealed using pull-out test combined with computed tomography scanning. Thereafter, a finite element model is established to analyze the effects of strain-hardening property on failure mechanism and anchorage performance. The regularity of bond stress distribution along the rebar is also obtained. Subsequently, parametric analyses are developed to analyze the effects on bond stress, including the embedded rebar length, concrete cover thickness, and tensile strength and ductility of UHPC. Expressions for the non-uniform distribution of bond stress are established. Finally, a calculation formula is proposed for the anchorage-bearing capacity considering the strain-hardening property of UHPC material. [ABSTRACT FROM AUTHOR]

In order to study the seismic performance of full-scale straight-tenon joint, a precise finite element analysis has been conducted based on the orthotropic constitutive relationship of wood and a modified Coulomb friction model. The hysteretic and skeleton curve, stiffness degradation, energy dissipation capacity, deformation capacity, and stress distribution are obtained through the finite element model and test results are utilized for calibration. Besides, parameter analyses considering size effect, friction coefficients, material properties, and axial loads on the column are performed. Results demonstrate that the precise finite element model can well reflect the seismic behavior of the straight-tenon joints. The hysteretic curves in simulation and test results are both anti-"Z" types with an obvious pinching effect. The initial stiffness is large, and stiffness degrades obviously with the increment of rotation. At the same rotation, the larger the scale of the model is, the greater moments and stiffness of the joints are, but the relationship is not linear. Friction coefficients and compressive strength in the parallel-to-grain direction mainly influence flexural capacity of the joint but have little effect on rotational stiffness. The rotational stiffness and flexural capacity are slightly affected by elastic moduli and axial loads. [ABSTRACT FROM AUTHOR]

Prediction of stresses in adhesively bonded joints requires high effort in determination of relevant material properties, which change during cure. In addition, the computational effort using complex viscoelastic finite element (FE) models impends efficient prediction of stress build-up. Rotational and oscillatory rheometry can help to reduce the experimental effort by measuring of modulus of elasticity (MoE) and axial shrinkage along curing. In this publication, shrinkage, development of MoE and Poisson's ratio of a curing adhesive were numerically modelled between two parallel rheometer plates in order to calculate cure-induced stresses using finite element analysis (FEA). To identify effects of different material properties on stress distribution, a parameter study was carried out and the reciprocal influence of the varied parameters was investigated. Consequently, resulting stresses within the adhesive layer and occurring deformations were investigated with respect to curing time as well as their location. The results showed that final shrinkage and MoE need to be considered not only in final values but also in terms of course of shrinkage and reaction. Stress build-up led to deformation of the rheometer plates, which has to be considered when using rheometry for determination of cure shrinkage. [ABSTRACT FROM AUTHOR]

Panel pad bending is a critical process to improve the screen-to-body ratio of an active-matrix organic light-emitting diode (AMOLED) panel. The failure analysis of the metal wirings is the key to ensure the reliability of signal transmission when the pad be bent to the back of the panel. In the present work, the sub-modeling technique combined with the periodic boundary condition was used to simulate the stress distribution of the bending area of the pad. The progressive failure of bent metal wirings was investigated by the extended finite element method. It is proved to be rational to prevent the wirings damage if the interlayer dielectric is replaced by an organic layer. In order to reduce stress of metal wirings, it is a measure to replace the original ultraviolet (UV) curable adhesive with a higher-modulus UV adhesive. The simulated results also show that rectangular perforations can avoid the stress concentration caused by the holes compared with circular perforations. For better stress distribution of metal wirings, it is necessary to increase the lengths of the rectangular holes and decrease the widths of that to a certain extent, which is helpful for restraining crack propagation by means of low-stress zones and holes. [ABSTRACT FROM AUTHOR]

Residual stresses distributions induced by heat treatment of AA 7075-T6 alloy were modeled and simulated. Models of quenching followed by tempering were developed and simulated using the Finite Element Method (FEM). To determine the convection coefficients used in these models, an inverse method coupled with optimization algorithms was developed. The simulated residual stresses distributions were validated by comparing these stresses with those determined experimentally using layer removal and contour methods. The layer removal method consisting into remove successive layers of material by milling was also modeled and simulated using FEM to predict not only the residual stresses, but also part distortion. The predicted part distortion was close to that measured experimentally, which proves the hypothesis that the residual stresses induced by the layer removal method do not affect part distortion. The contour method was used to validate the residual stresses determined by layer removal, and to evaluate the effects of the temperature gradient on the residual stress distribution. [ABSTRACT FROM AUTHOR]

The effect of a rectangular convex/concave shape formed on adherend surfaces in terms of preventing the crack growth of adhesively bonded joints was analytically investigated. The finite element method was used to evaluate crack growth resistance along the crack path by simulating a double cantilever beam test in which a single convex/concave shape was formed on the adherend material. The obtained crack growth resistance clearly demonstrated that both concave and convex shapes improved the apparent fracture toughness; i.e., the convex/concave shape functioned as a crack arrester. We identified the cause of the improvement as the dispersion of energy allocated to crack propagation due to the accumulation of the strain energy or the reduction of the stress concentration at the crack tip. It is noteworthy that the crack growth was arrested even when the convex shape did not interrupt the crack path. [ABSTRACT FROM AUTHOR]

Residual stresses, related distortions and cracks are detrimental in metallic Additive Manufacturing (AM). Previously developed stress-control strategies based on reducing thermal gradients hardly diminish the stress concentrations at the built basement and easily affect other physical phenomena involved in AM. To overcome this, a novel strategy, named as Smart-Substrate, consisting of optimising the inner structure and local stiffness of the substrate is proposed to avert stress accretion and related part deformations. To demonstrate its advantages, a coupled thermomechanical finite element model for AM, experimentally calibrated with in-situ temperature and displacement measurements, is employed to analyse the thermal and mechanical behaviour of three groups of different structures with increasing geometrical complexity (single-wall, rectangular and block parts) fabricated by Directed Energy Deposit (DED) on the standard and smart substrates, respectively. Through using Smart-Substrate, the generation of residual stresses, especially the stress concentrations at the bottom corner of DED-builds being highly sensitive to cracks, and the induced deflections, are fundamentally throttled, and contrariwise for the standard substrate. More importantly, the use of Smart- Substrate is almost without prejudice to the temperature field, metallurgy and resulting mechanical hardness. This provides a possibility for addressing different physical problems individually, enlarging the AM process window. [ABSTRACT FROM AUTHOR]

The effects of screw diameter, pilot hole, and material type on withdrawal load resistance (WLR) of screw driven in medium density fibreboard (MDF) and particleboard (PB) were investigated through using experimental and numerical methods. Meanwhile, the results of experimental tests and numerical analysis were compared with the empirical equations. The results showed that (1) the material type and the diameter of screw had significant effects on the WLR, but the pilot hole was not; (2) the equations proposed in Eurocode 5 had better performance in predicting WLRs of screw in both MDF and PB than the other equations; (3) density distributions of wood-based materials affected the mechanical behaviours of WLR of screw; (4) finite element model (FE-model) established could be used to simulate the WLR of screw in wood-based samples; (5) the complex FE-model considering threads of screw can reflect the stress distributions on threads in detail, which contributes to optimal design of threads geometry of screws. And the simplified FE-model without considering threads of screw had advantages in predicting the WLR with higher accuracy. [ABSTRACT FROM AUTHOR]

Instability failure of rock masses containing joints has always been a hot topic in rock mechanics. To study the mechanical failure mechanism of rock masses containing internal joint under impact loading, a digital laser dynamic caustic system combined with high-speed photography was used to perform drop hammer impact experiments. The mechanical parameter of dynamic fracture of polymethyl methacrylate (PMMA) beams and physical parameters such as crack extension trajectory and extension velocity were obtained. The extended finite element method was adopted to simulate the propagation process of the internal joint in the PMMA beam, then the von Mises stress distribution and crack extension velocity were obtained. The research results show that: the fracture mode of the three-point bending beam containing internal prefabricated crack is Mode-I; the lower end of the internal crack starts to crack firstly and the initiation toughness shows a tendency to increase and then decrease as the distance between the crack and the specimen boundary ascends; the "unloading stress wave" excited by the prefabricated crack lower end can significantly increase degree of the stress concentration at the crack upper end and promote the cracking. For specimens containing internal crack at different positions, the initiation toughness of the crack upper end increases by 152%, 62%, 88%, 250%, and 176% compared with lower end, respectively. The dynamic failure mechanism of a three-point bending beam containing internal joint has been proposed based on experiment results and numerical simulation. The proposed dynamic failure mechanism facilitates better understanding of failure process of rocks containing joint and for engineering applications related to rock mass fracture. [ABSTRACT FROM AUTHOR]

Efforts have been made to streamline the abstract as follows. If further changes are made we are concerned that the integrity of the content may be compromised. We hope you will understand. This study aimed to investigate the impact damage experienced by Pucheng crisp pears during various stages, including harvest, transportation, and processing. Drop impact tests were conducted on pears, considering drop height and collision contact material as factors influencing damage. The bruise area was used as an indicator for damage evaluation. Additionally, the pressure-sensitive film technique was employed to measure the contact stress distribution characteristics of Pucheng crisp pears after the drop impact. The relationship between contact stress distribution and damage area was examined, and the stress area range close to the damage area was determined. The results revealed that the damage area of pears increased linearly with the increasing drop height. Among the four contact materials, foam board exhibited the best cushioning properties, with a maximum safe drop height of 20 cm. The pressure distribution tended to follow a normal distribution, with a pressure range of 0.2-0.3 MPa covering the largest area, corresponding to the majority of the bruise area on the pears. Furthermore, the pressure area and average pressure were found to be related to the severity of bruising. When pears were dropped onto steel, rubber plate and corrugated board, for the former two the stress area exceeding 0.2 MPa closely approximated the damage area, with an average relative error of 7.2%. For the latter, the closest range was above 0.3 MPa, with an average relative error of 3.6%. However, when dropped onto foam board, the average relative error was 75%. This research provides valuable insights for designing packaging tools to minimize damage and serves as a theoretical basis for predicting and assessing pear bruise area using finite element analysis. [ABSTRACT FROM AUTHOR]

This study investigates the bearing capacity of strip footings resting on unsaturated soils subjected to combined loading using the lower-bound limit analysis coupled with the finite element discretization approach. In this regard, second-order cone programming (SOCP) is exploited to simulate the nonlinear form of the universal Mohr-Coulomb yield criterion during the process of stress field optimization. The significant influence of matric suction induced below the surface footing was accounted for by adopting the suction stress concept under the no-flow and steady-state infiltration/evaporation flow conditions. The eccentricity and inclination of the foundation loading are introduced into the equilibrium equations along the strip footing so as to render various combinations of moment (M), vertical (V) and shear (H) forces. The results stemming from the lower-bound finite element limit analysis are compared with several previous studies throughout the literature for verification of the model. The substantial contribution of suction stress to the evolution of failure loci and the distribution of subsurface stresses for the shallow foundation subjected to inclined and eccentric loadings is thoroughly discussed. A general three-dimensional failure envelope is presented for shallow foundations resting on partially saturated soils under combined vertical, horizontal and moment loadings. [ABSTRACT FROM AUTHOR]