Search

Some of the main applications of geosynthetics include use as a hydraulic barrier in sanitary landfills, as a reinforcement element and in pavement engineering. In most cases, these materials are subject to the overlapping effects of tensile strength and puncture. This paper presents a review of indirect methods for calculation of stress and strain averages by means of the California Bearing Ratio (CBR) puncture strength test. In addition, a new calculation method is proposed based on the Kirchhoff plate theory, which interprets the behavior of thin circular plates subjected to a uniform normal loading. This new method enables analysis of the stress-strain in each stretch of the geosynthetic. The methodology is applied to four woven geotextiles of different weights. The results of the new calculation method yielded a better stress-strain correlation with direct tensile strength tests, presenting the smallest relative errors compared to the other indirect calculations reviewed. With the aid of a disk and pins, vertical displacement values at different points in the geotextiles were measured and showed good agreement with analytical predictions. Therefore, the static puncture test combined with the new proposed calculation method is a good alternative for determining the stress-strain parameters of geotextile.

Boilers are one of the most used units for both heat generation plants and industry systems. Their operation is subjected to different working loads and maintenance requirements. Exploitation experience points out critical boiler zones where failures and break downs typically occur. This paper analyzes critical zones in hot water fire-tube boiler. Experimental procedure was performed on the model of this type of boilers and its critical element. The tube plate of hot water boiler was identified as the most critical one. Experimental analysis and numerical model verification were performed using Aramis system based on 3D Digital Image Correlation method. Numerical analysis was done in Ansys Software Package and verification of results was done based on measurements obtained by strain gauges and local measurements performed by the Aramis system. Stress-strain analysis indicates the critical zones of boiler tube plate. The character of change parameters such as strain and stress occurring in the critical zones can be verified both by experimental and numerical data. The paper presents a novel approach in experimental and numerical analyses that can be conducted in similar units and used for existing unit optimization, as well as for new product testing on different loads and provide opportunity for further development and improvement for practical industrial application.

Corrugated steel beams represent a promising area of research in the fi eld of structural engineering today. The article studies the behavior of a metal beam with a corrugated wall of an I-profi le under bending conditions. Beam considered span of 12 m. A fi nite element model of the calculated structure was built in the LIRA-SAPR software package. The analysis of the stress-strain state of a corrugated beam of variable stiff ness, which has a fl at fragment in the central part of the wall, is carried out. The beam thus obtained has a number of advantages over beams with only a fl at or fully corrugated wall. The conclusions based on the results of the analysis of the calculation are presented.

The stress–strain characteristics of reinforced masonry (RM) under axial compression should be correctly understood to effectively analyse and design RM elements. However, past studies have overlooked this aspect and mainly focused on assessing the stress–strain behaviour of grouted or confined masonry. An experimental programme was executed in this research by constructing and testing RM wallettes under uniaxial compression to understand the stress–strain behaviour of RM. The effects of grout strength and lateral restrainer configurations on the compression behaviour were also studied. The experimental outcome revealed that the grout plays a major role in the axial capacity of the RM, while change in the configurations of the lateral restraining reinforcement did not significantly affect the axial capacities and axial stress–strain behaviour of RM wallettes. The predictability of the axial capacity of the RM wallettes were validated through the expressions given in the three masonry design standards. It was observed that all considered standards conservatively predicted the axial capacity of the RM. Moreover, the applicability of the existing analytical models in the literature for the RM were verified against the experimental data and an improved stress–strain model is proposed in this research.

To investigate the seismic performance of underground structures under the action of the structure-soil interface, in this study, experiments were performed using plexiglass structures (two pieces) and a concrete structure (one piece) as the research objects. The surface of one plexiglass structure was prepainted with a layer of cement mortar as the contact surface between the structure and soil, and the other plexiglass structure was not treated and used for comparison. A rigid model box measuring 2.25 m × 2.25 m × 1.5 m was placed on a 3 m × 3 m shaking table, and the box was filled with the configured model soil and the underground structure prepared in advance. Input transverse uniform excitation was imparted to the whole system. A shaking table model test was performed on the underground structures to analyse the acceleration response, stress strain, and earth pressure changes in the underground structure, and the influence of the contact surface on the seismic dynamics of the underground structure was evaluated. The test results showed that under uniform excitation, the dynamic characteristics of the underground structures were greatly affected by the intensity and depth of the seismic waves. (1) When the soil-structure contact was considered, the stress and strain of the structures increased significantly, and the stress-strain value was significantly greater than the stress-strain value of the soil-structure interface in a fully bonded state. (2) There were inconsistencies between the acceleration peak curve of the plexiglass structure considering the contact effect and the acceleration peak curve of the plexiglass structure without considering the contact effect. The difference between the two lies mainly in the corresponding maximum peak acceleration and the Fourier spectrum amplitude. With respect to the value and frequency composition, regardless of whether the input acceleration intensity was 0.2 g or 0.5 g, the peak acceleration of the organic structure was greater when the contact surface effect was considered than without the contact surface effect. Therefore, the structure-soil interface needs to be considered in actual engineering. The presence of the contact surface improves the safety of the structure and is helpful for seismic design. The results of this study provide a basis for further research on the influence of soil-pipe contact on the seismic response of underground structures.

Each structure is exposed to different influences during operation. As a result, there are various defects and damages of these elements that affect their safe operation. The article presents the results of experimental studies of reinforced concrete beams with damages to stretched reinforcement made with and without initial load application. As the damages were accepted one or five Ø5.6 mm holes. In one case, the damage was made until the beam destruction (up to the 8.4 mm opening) Control samples of both series were destroyed due to crushing of the compressed zone of concrete. Samples that were damaged without initial loading collapsed due to rupture of the stretched reinforcement. The same type of failure was identified for damages at the operational load level.

PurposeIn this paper the use of classical strain measures in analysis of trusses at finite deformations will be discussed. The results will be compared to the ones acquired using a novel strain measure based on the Hyperbolic Sine function. Through the evaluation of results, algebraic development and graph analysis, the properties of the Hyperbolic Sine strain measure will be examined.Design/methodology/approachThrough graph plotting, comparisons between the novel strain measure and the classic ones will be made. The formulae for the implementation of the Hyperbolic Sine strain measure into a positional finite element method are developed. Four engineering applications are presented and comparisons between results obtained using all strain measures studied are made.FindingsThe proposed strain measure, Hyperbolic Sine, has objectivity and symmetry. The linear constitutive model formed by the Hyperbolic Sine strain and its conjugated stress presents an increasing stiffness, both in compression and tension, a behavior that can be useful in the modeling of several materials.Research limitations/implicationsThe structural analysis performed on the four examples of trusses in this article did not consider the variation of the cross-sectional area of the elements or the buckling phenomenon, moreover, only elastic behavior is considered.Originality/valueThe present article proposes the use of a novel strain measure family, based on the Hyperbolic Sine function and suitable for structural applications. Mathematical expressions for the use of the Hyperbolic Sine strain measure are established following the energetic concepts of the positional formulation of the finite element method.

In recent years, with the development of aerospace field, composite materials show its importance and particularity in many fields and have a wide range of application potential because of its light weight structure. The application of composite materials to UAV blades can reduce the structural weight and improve the impact resistance. The mechanical properties, damage performance and failure mechanism of laminate under high strain rate are the fundaments for high-speed impact mechanics analysis. In this paper, a kind of fiber composite blade is designed independently, and the optimal laying angle is determined. Fluent is selected as the CFD calculation software to carry out the fluid–solid coupling analysis of the composite fixed wing. By changing the wing angle (0°, 10°, 17°, 24°), the flutter performance of the fixed wing under the condition of 45 m/s velocity flow is studied. The results show that the laminated laminate designed in this paper has longer action time under impact load, better protection for structure and better effect of resisting impact, and the trend and inflection point of stress and deformation of fixed wing are similar. Flutter occurs, the stress on the lower side of the fixed wing is larger than that on the upper side, and the stress on the outside is larger than that on the inside, and with the increase of time, the stress gradually spreads to both sides along the direction of the fixed wing. There is no correlation between the stress and strain of the fixed blade, and there is a threshold for the wing angle. When the wing angle is 10°, the blade has the smallest strain and the strongest wind resistance.

Tunnels are generally designed for a sustained usage of 80 to 100 years, during which the safety of tunnel structures must be guaranteed. A common supporting form utilized in contemporary tunnel engineering is composite lining. To derive applicable parameters of the supporting form and therefore ensure the long-term safety of the tunnel structure, it is imperative to determine the extra acting force exerted onto the composite lining by the creep of the rock surrounding the tunnel and to calculate the stress-strain characteristics of composite lining. In the current study, this paper proposes an approach termed surrounding reinforcement, which is based on the homogenization method. Specifically, this paper defined the bolt force as the internal force of the surrounding rock, analyzed their viscoelastic-plastic properties using the unified strength theory, and derived an equation for calculating the stress-strain relationship of the composite lining. To further validate the method in tunnel structures, this paper applied the derived equation to a representative instance. The results of this paper show that the initial support force has also increased during the creep process of the surrounding rock, indicating that engineers should pay close attention to the coordination between the strength of initial support and the secondary lining and thus ensure an optimal distribution of the pressure from the surrounding rock when designing composite lining tunnel within weak strata. This paper proposes that the initial support not only would guarantee the tunnel safety during the construction stage but also could cooperate with the secondary lining to brace the stress caused by the creep, ensuring that the supporting structure stays stable across the whole period of tunnel operation. This paper provides an alternative to previous methods that is more comprehensive, with simpler calculations, and more applicable to the composite lining supporting design within weak strata.

Engineering machines and components are proneto structural failures during their service time due to certaintechnical reasons and also due to some unforeseencircumstances. The technical breakdowns sometime lead tohigh economic imbalance and can also be fatal to life andproperty. Predicting the failure and evaluating the breakagecharacteristics of engineering components are crucial indetermining the life of the component and also increasetheir maintenance and safety in daily life. This research study deals with the modelling andnumerical simulations of an aluminium alloy specimen in3D stress-state and thereby predicting the fatigue failure ofthe material subjected to external cyclic loadings. Topredict the failure of a component, a specimen with aninduced crack can be evaluated through cyclic loadingprocess. It is based on the fact that the presence of a crackstends to modify the stresses present locally on thecomponent that the elastic deformation and the stressesattributed with them are totally insufficient for the designagainst fracture. It is based on the assumption that thespecimen undergoes complete fracture when the crackreaches its critical size even though the stress at the criticalcrack tip is much lower than the yield stress of thecomponent. The critical size of the crack is based on theapplication of the load and the number of load cycles itundergoes.The main aim of this research is to present andvalidate the numerical method for the study of theinfluence of cracks present in the engineering components.Finite element method was applied for numericalsimulation. In this study the tension, torsion, combined tension-torsion and fatigue loads was applied. Theexperimental testing data of mechanical properties wasused in numerical simulation as input data. This researchstudy investigates the three-dimensional stress-strain stateand fatigue prediction of D16T aluminium alloy which ispredominantly used in the aerospace and automobileindustries for their high strength-to-weight ratio and muchbetter physical properties. The different specimen modelsare then analysed and the most efficient one was selectedfor the preliminary experimental tests.

Relevance. In recent years, composite materials have become widespread in the construction of reinforced concrete structures for industrial, civil and transport structures. It is proposed to strengthen the reinforced concrete structures of hydraulic structures with prestressed basalt composite rebar. It took an experimental and theoretical substantiation of technical solutions to strengthen the reinforced concrete structures of hydraulic structures with prestressed basalt composite reinforcement. The aim of the work was to carry out a set of experimental and theoretical studies of the stress-strain state and internal forces in low-reinforced concrete structures of hydraulic structures reinforced with prestressed basalt composite rebar. Methods. Experimental studies of the stress-strain state and internal forces were carried out on the basis of low-reinforced concrete beam-type models with interblock construction joints, harden with prestressed basalt composite reinforcement in the stretched (compressed) zones of the models. Theoretical studies of the stress-strain state and internal forces were carried out on the basis of the theory of reinforced concrete and structural mechanics. Results. As a result of the research carried out on typical low-reinforced concrete structures of hydraulic structures with interblock construction joints, the main stages of the stress-strain state of hydraulic reinforced concrete structures were formulated. Based on the data of experimental and theoretical studies, taking into account the reinforcement with prestressed basalt composite rebar, as well as with prestressed clamps in the shear zone, a method was developed for calculating the strength of low-reinforced hydrotechnical reinforced concrete structures with interblock construction joints.

This paper mainly studies the stress and strain characteristics of electric vehicle cables under tensile state and its influence law on the electromagnetic characteristics. Firstly, the structure and characteristics of new energy vehicle cables are analyzed, and the three-dimensional solid model of the cables is established. The finite element method is used to analyze the deformation law and stress change characteristics of cables under different tensile load conditions, so as to achieve the resistance change law of cables. Then the equivalent modeling method is established to simulate the electromagnetic characteristics of the cable. It is found that the tensile deformation increases the electromagnetic field intensity of some parts of the cable, leading to the irregular distribution of electromagnetic field in the entire cable. Finally, the variation law of electromagnetic field during the cable deformation is summarized.

Providing accurate constitutive stress–strain relationships for confined concrete can increase the reliability of the moment curvature (MC) analyses in the displacement-based seismic design of reinforced concrete (RC) columns. This paper presents a new stress–strain model for high-strength concrete (HSC) tied square columns which exhibit a more brittle behavior than normal strength concrete (NSC) members. Introducing the concept of least confined volume in the damage localization zone at the middle of the concrete core, a new approach is developed for the confinement stress distribution of lateral ties. In order to determine the lateral stresses acting on the vertical surfaces of the least confined volume, the effective confinement stresses are reduced considering the tie configuration. The peak strength and the ductility of the column should therefore be calculated for the confined concrete in this region. A concrete failure criterion applicable to multi-axial compression due to the reduced confinement stresses in two orthogonal directions, is then used to determine the ultimate strength of HSC columns. Moreover, plotting the compression meridian of the failure criterion, a simple and design-oriented formula is proposed for the ultimate strength of HSC tied columns. The validity of the proposed approach and the performances of two well-known analytical models are verified against the test results of eighty-six HSC columns from five different experimental studies for both the axial stress–strain behavior and the ultimate strength. Besides, the implementation of the concept of the reduced confinement stress in the Mander’s model leads to a significant improvement in its capability of predicting the triaxial strength of HSC.

Based on bilinear hardening material model, the swage autofrettage technology of steel sleeve for pump is analyzed. The theoretical calculation formulas of stress, strain, residual stress and strain and punch thrust of swage autofrettage steel sleeve are derived by the elastic-plastic analysis. The accuracy of the theoretical formulas is verified by the swage autofrettage experiment. The result of theoretical calculation is consistent with that of the experiment, and the process of the second loading does not affect the autofrettage result. The theoretical calculation formulas can be used to guide the swage autofrettage technology design of the steel sleeve for the pump.

The present study deals with the extended version of our previous research work. In this article, for predicting the entire weld bead geometry and engineering stress–strain curve of the cold metal transfer (CMT) weldment, a MATLAB based application window (second version) is developed with certain modifications. In the first version, for predicting the entire weld bead geometry, apart from weld bead characteristics, x and y coordinates (24 from each) of the extracted points are considered. Finally, in the first version, 53 output values (five for weld bead characteristics and 48 for x and y coordinates) are predicted using both multiple regression analysis (MRA) and adaptive neuro fuzzy inference system (ANFIS) technique to get an idea related to the complete weld bead geometry without performing the actual welding process. The obtained weld bead shapes using both the techniques are compared with the experimentally obtained bead shapes. Based on the results obtained from the first version and the knowledge acquired from literature, the complete shape of weld bead obtained using ANFIS is in good agreement with the experimentally obtained weld bead shape. This motivated us to adopt a hybrid technique known as ANFIS (combined artificial neural network and fuzzy features) alone in this paper for predicting the weld bead shape and engineering stress–strain curve of the welded joint. In the present study, an attempt is made to evaluate the accuracy of the prediction when the number of trials is reduced to half and increasing the number of data points from the macrograph to twice. Complete weld bead geometry and the engineering stress–strain curves were predicted against the input welding parameters (welding current and welding speed), fed by the user in the MATLAB application window. Finally, the entire weld bead geometries were predicted by both the first and the second version are compared and validated with the experimentally obtained weld bead shapes. The similar procedure was followed for predicting the engineering stress–strain curve to compare with experimental outcomes.

An analytical method for determining the compliance of gear teeth, the load distribution factors, and the bending stresses is proposed. To solve the problem about the stress–strain state of the gear tooth, the latter is represented as a wedge with the angle of the roll corresponding to the pressure angle of the involute tooth. The mathematical model of the loaded tooth is given in the form of an inhomogeneous Volterra integral equation with the kernel depending on the difference in the arguments solved by the method of operational calculus. Using the results of the study in strength evaluation of gear trains allows more accurate determination of their loading capacity.

SUMMARYEarthquake ruptures and seismic sequences can be very complex, involving slip in various directions on surfaces of variable orientation. How is this geometrical complexity in seismic energy release, here called mechanism complexity, governed by tectonic stress? We address this question using a probabilistic model for the distribution of double couples that is consistent with three assumptions commonly used in regional stress inversions: the tectonic stress is constant, slip vectors are aligned with the maximum shear traction in the plane of slip, and higher shear traction promotes more seismic energy release. We characterize the moment-tensor field of a stress-aligned source process in terms of an ordered set of principal-stress directions, a stress shape factor R, and a strain-sensitivity parameter $\kappa $. The latter governs the dependence of the seismic moment density on the shear-traction magnitude and therefore parametrizes the seismic strain response to the driving stress. These stress–strain characterization (SSC) parameters can be determined from moment measures of mechanism complexity observed in large earthquakes and seismic sequences. The moment measures considered here are the ratio of the Aki moment to the total seismic moment and the five fractions of the total-moment defined by linear mappings of the moment-tensor field onto an orthonormal basis of five deviatoric mechanisms. We construct this basis to be stress-oriented by choosing its leading member to be the centroid moment tensor (CMT) mechanism and three others representing orthogonal rotations of the CMT mechanism. From the projections of the stress-aligned field onto this stress-oriented basis, we derive explicit expressions for the expected values of the moment-fraction integrals as functions of R and $\kappa $. We apply the SSC methodology to a 39-yr focal mechanism catalogue of the San Jacinto Fault (SJF) zone and to realizations from the Graves–Pitarka stochastic rupture model. The SJF data are consistent with the SSC model, and the recovered parameters, $R = {\rm{ }}0.45 \pm 0.050$ and $\kappa = {\rm{ }}5.7 \pm 1.75$, indicate moderate mechanism complexity. The parameters from the Graves–Pitarka realizations, $R = {\rm{\ }}0.49 \pm 0.005,{\rm{\ \ }}\kappa = {\rm{\ }}9.5 \pm 0.375,$ imply lower mechanism complexity than the SJF catalogue, and their moment measures show inconsistencies with the SSC model that can be explained by differences in the modelling assumptions.

The multiaxial character of high-speed railway brake disc thermomechanical fatigue damage is studied in this work. Although the amplitudes and distributions of temperature, strain and stress are similar with uniform and rotating loading methods, the multiaxial behavior and out-of-phase failure status can only be revealed by the latter one. With the help of a multiaxial fatigue model, fatigue damage evaluation and fatigue life prediction are implemented, the contribution of a uniaxial fatigue parameter, multiaxial fatigue parameter and out-of-phase failure parameter to the total damage is discussed, and it is found that using the amplitude and distribution of temperature, stress and strain for fatigue evaluation will lead to an underestimation of brake disc thermomechanical fatigue damage. The results indicate that the brake disc thermomechanical fatigue damage belongs to a type of multiaxial fatigue. Using a uniaxial fatigue parameter causes around 14% underestimation of fatigue damage, while employing a multiaxial fatigue parameter without the consideration of out-of-phase failure will lead to an underestimation of about 5%. This work explains the importance of studying the thermomechanical fatigue damage of the brake disc from the perspective of multiaxial fatigue.

This paper reports the development and verification of a new procedure for formation of a complete stress-strain curve of concrete with a downward region of strain by using a digital image correlation method. A new technique to build spectle patterns on the surface of concrete is described. That makes it possible to accurately enough reproduce the spectle patterns on the surface of concrete and perform a high-quality analysis of strains involving digital image correlation. The advantages of this research technique have been established when predicting the formation of internal cracks in concrete followed by their propagation. In addition, using the digital image correlation methodology makes it possible to obtain strains of the entire studied plane of the sample at each stage of loading. This procedure provides an opportunity to investigate a change in strains and the movement of individual points or areas when studying concrete surfaces. That is a relevant issue as it enables more detailed diagnostics of existing reinforced concrete structures. To check the accuracy of this procedure application, a mechanical gauge with an accuracy of 0.001mm was additionally installed. 2 high-speed monochrome CCD cameras with different lenses were used in determining concrete strains involving the digital image correlation technique. The deformations were controlled with a period of time every 250ms. The load was controlled by an additional third camera with a speed of 50frames/second. The result of the experimental study is the formed full concrete destruction diagram with a downward region of strain. The deviation of the results of strains based on the mechanical gauge with an accuracy of 0.001mm with a base of 200mm from those acquired by the digital image correlation procedure was mainly up to 10%, which confirms the reliability of the results. The results of this work allow a more accurate calculation of reinforced concrete structures in the practice of design, inspection, or reinforcement of existing structures

Predicting the behavior of concrete in a Concrete-Filled Steel Tubular (CFST) column is challenging due to the sensitivity to input parameters such as the size of the cross-section, the material modeling, and the boundary conditions. The present paper proposes a new modified finite element model to predict the behavior and strength of a CFST subjected to axial compression. The development is based on the concrete damaged plasticity model, with its stress-strain relationship revised from the available model. The predicted accuracy of the modified model is verified via a wide range of experimental tests. The proposed model has more accuracy than the available models in predicting the ultimate compression strength. The results show good agreement with the test data, allowing its use in modeling CFST columns.

Generally, confinement models of the steel-fiber concrete were very ductile because the fiber has a significant influence on the increase of the concrete deformability. Nevertheless, the existing steel fibrous confined models now have significant differences between each other, especially the peak stress value and post peak behavior. It is some of the different reviewed design parameters that affect the stress-strain equation of developed confined steel-fiber concrete. This paper investigated the existing confinement models to evaluate pre- and post-peak behavior of experimental results of confined steel fiber concrete for square sections. This paper has discussed models of existing steel fibrous concrete restraints compared to the results of experiments. In general, it can be concluded that the Hsu model is able to predict the best K value and ascending branch curve toward the experiment results. However, in the unfettered concrete ductility of the descending branch curve, the predicted values of e' cc and e50cc, it can be said that all the models reviewed are still not able to model properly. The difference is mainly due to the parameters reviewed to lower the restraints of each model are not the same. The comparison results presented in this paper recommend the need for more complete experimental research with broader parameters such as cross-sectional shape, fiber ratio, and restraint bone characteristics, in order to lower the model of restraint more generally.

The determination of mobility of the concrete foundation on a natural subgrade is rather relevant for the strength analysis of multistory brick buildings with a spatial cross-wall structural system. During the inelastic soil behavior, its ultimate limit and elastoplastic states are allowable along the concrete foundation perimeter, the bearing capacity of the foundation being provided as a whole. In this case, it is important to adhere to the standard conditions of the foundation deformation and mobility. The finite element modeling of the stress-strain state of the concrete foundation and the building superstructure of the base-foundation-building system is performed in the MicroFe software package. A consideration of inelastic soil deformations in the natural subgrade results in unacceptable displacements of the concrete foundation.

Concrete-encased concrete-filled steel tube (CECFST) columns and partially encased composite (PEC) beams are both steel-concrete composite members which have outstanding advantages and have been applicated in some engineering constructions. This paper makes an attempt to employ blind bolting technique to assemble CECFST columns to PEC beams. For the purpose of exploring the mechanical performance of this type of assembled joints, firstly, a nonlinear finite element (FE) model was established and validated, where complicated contact interaction was taken into consideration. Plenty of parametric analysis were adopted to find out the effect of ten parameters on strength and initial stiffness of the assembled joint. Numerical analysis showed that mechanic behavior is notably affected by axial load ratio, width and thickness of end-plate, bolt pretension force, bolt diameter, and steel ratio of CECFST column. Full-range analysis was then carried out to observe stress and strain developments and failure modes. Load transfer mechanism in CECFST column was also studied. Design methods to estimate the flexural capacity and initial stiffness of the connections were proposed in accordance with the component models. In comparison, it could be concluded that the calculation results fit well with the analytical results, which confirms that the design formulas could provide a favorable basis in practical design.

The article discusses the calculations of some structures under various laws of deformation. Three laws are adopted: linear, non-linear exponential, non-linear with a falling direction, taking into account the creep of concrete. As a result of the calculation, results are given for various efforts, comparative characteristics are given, and conclusions are drawn about the work of structures and about the work of materials.

Object and purpose of research. This paper discusses numerical simulation possibilities in terms of stress-strain monitoring for marine engineering structures. This approach can simulate the behavior of strain gauges for both elastic and plastic material behavior. Materials and methods. FEM-based simulation of strain gauge operation process taking into account geometric and physical non-linearity. Main results. Development of refined FE models for sensor installation area of stress-strain monitoring system. Numerical simulation of uniaxial and triaxial strain gauge operation. Time histories of strain gauge readings for linear and non-linear behavior of material. Sensitivity analysis of strain gauges in terms of various strain types. Update of strain gauge arrangement for the best description of structural strains. Conclusion. These results demonstrate and confirm a strong potential of numerical models in development of stress-strain monitoring systems for engineering structures. Simulating strain gauge operation, these models make it possible to determine global strained state of given structure as per strain gauging data for some of its areas.

The present study involves the smart precast box culvert, which can sense the strain and stress achieved based on the fiber optic sensor embedded into the fiber-reinforced polymer. These culverts (2.00 × 2.00 × 2.00 m) was investigated experimentally with different seven trial load tests subject to join the dual box culvert using two steel strand and two smart steel strand (CH2&CH3) which is connected to fiber-reinforced polymer strain sensor for analyzing deformation sensor, line load strain, stress region, and stress–strain self-sensing of the culverts. From the monitored results in this self-sensing static load test, the maximum deformation sensor was 131.75 µɛ at the lower smart steel strand (CH3) and the cracks (0.10 mm) initiated on the roof slab of the culverts for a specimen due to bending moment in the culvert not exceeded its moment capacity because the applied load was smaller than the ultimate load. This paper proposes a series of fiber-reinforced polymer strain sensors to connect to the smart strand to completely meet the culvert’s requirements, and their sensing performance is come out. This study, therefore, implied that the experimental finding of the fiber-reinforced polymer strain sensors has the potential to monitor the structural health over time.

This report presents results of calculations of the service life of blood pumps based on energy criteria of dissipative failure for pneumatic ventricular assist systems. Calculations were carried out using mathematical modeling of the stress–strain state of diaphragms of thicknesses 0.3 and 0.5 mm. The effects of diaphragm thickness on service life were assessed using symmetrical and sawtooth loading cycles. The amplitudes of the maximal equivalent stress and the coefficients of residual strength (safety factor) for different diaphragm thicknesses were determined.

An algorithm is proposed for optimizing the internal structure of a sample obtained by 3D printing, while maintaining the mechanical strength and rigidity. The basis is the pre-calculated stress-strain state of the sample in an elastic isotropic setting. Numerical simulation results are obtained showing the performance of the optimized design using the example of the three-point bending problem. Comparison of the results of numerical modeling, optimized and monolithic samples, in elastic isotropic formulation is presented

Evaluation of the building element technical state relies on verification calculations using estimated construction material properties. Physical and mechanical properties are estimated predominately by using non-destructive test methods. The accuracy of these methods is affected by the level of stress-strain state of the structural element and present structural defects. The variability of the concrete properties over time under constant loads is a determining factor for the durability and reliability of the structural element. The influence of the physical and mechanical characteristics of a construction material on the deformation process of the local area of the structural element adjacent to the structural defect has been investigated. The research has been performed on structural models using software systems "LIRA SAPR" and "SOLIDWORKS". A structural model having dimensions of 100 x 100 x 400 mm was used for the study. Materials of concrete grades C12/15 through C25/30 with corresponding properties have been used. Load parameters for modeling of the deformation process varied from 0.1 to 0.5 of the ultimate loads. Performed calculations made it possible to obtain fields of stress, deformation and displacement under different model parameters and stress levels.

The paper presents basic approaches to assessment of strength, service life, and survivability of structural components of technical systems subjected to various types of operating loading regimes. These include: (i) thermo-mechanical loading regimes of normal operation inducing the states of stress and strain that can be considered using traditional stress-based methods and criteria; (ii) extreme design basis loading regimes related to design basis emergency situations that require a transition to design according to strain-based fracture criteria with accounting for temperature, force and frequency factors, and (iii) loading regimes induced by beyond design basis (accident and catastrophic) situations that should be analyzed using equations and criteria of nonlinear deformation mechanics in its most complex thermally coupled formulation.

Finite element analysis is a popular method used to characterize crack tip stress and strain fields in fracture mechanics problems. In a constraint-based elastic-plastic fracture mechanics, the crack tip stress and strains are essentially dependent on the accurate crack tip finite element configuration. Typical finite element software does not provide control of node and elemental numbering order and sequence which caused difficulty to examine different crack configuration state of stress–strain using automated post-processing codes. A method to automate the creation of finite element mesh of arbitrary lengths and shapes of standard and nonstandard fracture mechanics geometries using a geometric progression technique is described. A list of equations was proposed to develop nodal and elemental model data that represented a defined region of a cracked geometry. Assembly of the regions produced a finite element mesh representing a fracture mechanics cracked geometry which can be incorporated into a typical finite element program. The approach can eliminate the modeling processes of finite element of cracked specimens and offers the ability to control the nodal and elemental numbering system to allow systematic stress and strain elucidation for large degrees of freedom mesh and history-dependent incremental plasticity crack tip analysis. The approach used to develop the finite element mesh was discussed, and examples of the finite element mesh generated by the approach were compared to established two-parameter elastic-plastic fracture mechanics results. Finally, the algorithm codes used to develop the cracked models are supplied as supplementary files to interested users.

This paper presents an analysis of data resulting from the same material constitutive model, based on experimental data and model developed by Johnson and Cook. The same case of impacting a cylindrical body on a perfectly rigid target was run with four different mesh size (2 mm, 1 mm, 0.5 mm and 0.25 mm). Here, the comparing criterion was the maximum value of von Mises stress and the authors pointed out that the finest mesh here presented is closer to reality. Depending on the case application the engineers could adopt a finer or coarse mesh, but not so coarse to denaturate the reality of body deformation and failure. How to decide? Having performant computer resources (hardware and software) and running several mesh in order to notice the convergence of one parameter or, more reliable, a set of criteria that could include qualitative resemblance with actual bodies as concerning failure and deformation, experimental dat on strain, yield and failure of the involved materials, values of stress and strain, at the same time moments. From this study the following conclusions were formulated: finer mesh presents a earlier failure in time and calculated a higher stress for these moment.

Two-point incremental forming (TPIF) shows higher forming limits than single-point incremental forming (SPIF) especially for producing complex industrial functional components. However, unexpected failure still occurs occasionally under certain forming conditions in TPIF. In this paper, the applicability of six damage models for failure prediction in TPIF is evaluated. The procedure of damage parameter calibration and finite element modelling are presented. The predicted failure depth and location with these damage models are evaluated under different loading conditions. Furthermore, the stress and strain and damage evolution in TPIF are provided and discussed in detail. It is concluded that the failure location and depth can be predicted more accurately by the Ayada model than others in this work. It is noted that once double-sided contact occurs in TPIF, it reduces the variation of triaxiality through the thickness, altering the accumulation of damage.

The safety and stability of lining structures are core concerns of tunnel and underground engineering. It is crucial to determine whether a lining structure would crack and which direction the crack would expand with seismic excitation. In previous literature, the principle based on stress and strain has been widely used to predict the seismic damage of lining structures, whereas it cannot specify the cracking modes. Taking account of that deficiency, this paper introduces the strain energy density ratio (SEDR) principle and proposes a seismic damage prediction method for lining structures, which can precisely predict the crack positions and expansion directions. Moreover, numerical simulations of the typical seismic damage sections of two tunnels in the Great Wenchuan Earthquake and a calculating example of the theoretical equations are conducted to verify the proposed method. In summary, the numerical simulation results show that the arch springing cracks first, and the invert cracks next; then the cracks expand to the spandrel, and finally, they form oblique cracks, annular cracks, and longitudinal cracks, whose positions and patterns are in accordance with the field investigation results. In terms of the calculating example results, the obtained two-fold SEDR and cracking angle θ are 1.87 and −6.28°, respectively, which are consistent with the numerical simulation results. Therefore, one can see that the proposed seismic damage prediction method based on the SEDR principle is quite accurate. This method can be used to predict the seismic damage of lining structures and provide a reference for the research of the damage mechanism of tunnels.

A quadcopter is a widely used type of Unmanned Aerial Vehicle (UAV) due to its simple structure and vertical take-off and landing capability. The material and geometrical properties, affect significantly the performance of a quadcopter flight. This paper deals with the material optimization of quadcopter’s body frame, through Finite Element Analysis (FEA). A 3-D CAD model of quadcopter body frame has been designed analyzed using FEA. The Quadcopter body frame was analyzed for three different materials to find out the best suited materials namely, copper alloy, aluminium, and carbon fiber reinforced polymer (CFRP) to find out the best suited material for heavy transportation application. The vibrational frequencies are evaluated based on the modal analysis. In addition, the static structural analysis has been performed to determine the maximum stress and strain developed in the frame under static loading condition.

This paper focuses on the design and simulation of the hip joint prosthesis to validate the feasibility with Ti-6Al-4 V and TiNbZrTaFe high entropy alloy. The main precondition for the selection of these materials is its compatibility with the human body. Conventional metallic implants create several problems to patients, which include the systematic toxicity of released metallic ions due to corrosion, wear of joint replacement due to movement and fatigue failure of the structural component due to repeated loading. In this paper, a 2D/3D CAD model of an artificial hip joint was designed according to the ISO 7206 using SolidWorks Software program. The finite element (FE) method was used to obtain a solution for the stress and strain distribution throughout a series of the adjacent element. The static design was analysed using SolidWorks Simulation Software with loading condition of 250 N, 350 N and 450 N to check the durability of the design. Static behaviour of these functionally graded biocompatible materials, the properties which affect biocompatibility and mechanical integrity were discussed in detailed.

This scientific article is concerned with an effect of a technology factor that consists in the number and characteristics of microcracks resulted from grinding and polishing on the stress-strain behaviour and displacements of the sensing element’s moving parts. Microcrack dimensions, sizes, and relative positions after processing finishing operations were determined using an atomic-force microscope. An effect of a single microcrack was studied; its affected zone was established. The microcrack arrangement was set in 10 different ways. The most typical microcrack arrangements having the greatest impact on the item’s stress-strain behaviour in their location zone were selected. The item fixing conditions were the same for all cases. This was followed by calculation by the finite element method, for each individual case; the results were recorded in a table. Calculations were carried out for the second mode of the sensing element’s oscillations. The obtained results were used to build plots and draw conclusions on the effect of microcracks formed during the item fabrication. It was established that the farther the microcrack from the SE axis of symmetry, the lower the stresses in its location zone. The tangential arrangement of the microcrack had a greater impact than the radial one. A conclusion was drawn that it was necessary to increase the SE processing quality in the vicinity of a leg where the effect of microcracks is at the maximum. Thereafter, tasks were determined for further study of microcracks’ impact on the item reliability. In the end, a reference list consisting of 12 titles was compiled.

For an efficient use of adhesive joints, reliable prediction techniques should be made available to the designer. Simulation is usually accomplished by the Finite Element Method (FEM). However, in adhesive joints, the adhesive thickness is much smaller than that of the adherends, thus requiring a refined mesh to produce good results. Linked to this, the adhesive has to withstand high strains, causing mesh distortion and making difficult to attain solution. In these cases, meshless methods can be a good alternative, although these are not sufficiently validated yet. This work aims to implement the von Mises (vM) and Exponent Drucker-Prager (EDP) criteria into a user-built meshless method software based on the Radial Point Interpolation Method (RPIM), for the strength prediction of adhesively-bonded single-lap joints (SLJ). Validation with experiments is undertaken for a medium-ductile adhesive (Araldite® 2015) with varying overlap lengths (LO). Stress and strain distributions were plotted in the adhesive layer, and the failure load (Pm) was assessed by continuum mechanics failure criteria. The meshless method showed to be promising in predicting the behavior of bonded joints, although limitations were found by using continuum mechanics criteria.

The article discusses the features of the work of thin-walled profiles of light steel thin-walled structures (LSTS), used for the construction of prefabricated buildings. A brief description is given of the theory of stability of thin-walled rods based on the law of flat sections (Euler bending forms), the necessity of taking into account the seventh degree of freedom (deplanation of the cross section) when calculating LSTS for stability is revealed. The results of experimental studies of the stress–strain state (SSS) of LSTS under the influence of static compressive loads are presented. Relative deformations were monitored using strain gages and the digital image correlation method implemented in the Vic-3D digital optical system. The dependences of the main compressive stresses of the rack shelves on the applied compressive load and the field distribution of the relative longitudinal deformations of the rack walls as a result of speckle image processing in the Vic-3D system are presented. It was established that the loss of the bearing capacity of the studied LSTS from the loss of stability occurred from actual deformations, the values of which are significantly larger than the values ​​of the calculated deformations obtained from the calculation of stability based on the application of the law of flat sections.

This paper introduces the mathematical modelling method of geomechanical processes, for which the parameters are provided by surface displacement surveys and seismic data.

Flanges are vital component used in power generation plants for linking, closing and connecting of pipes to the boiler and turbine compartments. The linking of piping networks via this approach has limited the use of welding in the industry. High temperature, pressure and thermal transitions are presumed to influence the behaviour of bolted flange assemblies in service. Sadly, the behaviour of bolted steam pipe-flange assembly under these conditions have not been sufficiently studied. Thus, the usage, maintenance and replacement of the steam pipe flanges are based on assumptions which can have detrimental consequences. In order to investigate this under-researched area, the thermo-mechanical behaviour of a bolted X20 (12Cr-1MoVNi) steam pipe-flange assembly subjected to a typical power generation plant operational condition was determined using finite element analysis code, Abaqus CAE/2019. The stress and strain distribution across the assembly were computed and the maximum stress in the assembly was developed on the low temperature, high compressive stress side of the bolt’s shank while the maximum strain was developed on the interior surface of the pipe. Also, the value of the maximum stress (331.8 MPa) developed on the bolts is below the operational limiting stress of the assembly material, thus, indicating that the assembly is operating within the acceptable stress, but with the bolts being identified as the component most prone to failure.

This study evaluates the Concrete filled steel tubular sections (CFST) which is chosen based-on the features of its high capacity, economic, fire resistant and the better seismic act than steel structures. It utilizes the gain of both concrete and steel; it is preferred for its large energy inclusion capacity and degradation due to lower strength. CFST uses Steel tubes structures have sections thinner which are compared with normal columns made of steel. But members get deteriorated owing to environmental factors like ageing and corrosion. Under thought of these feasibilities a relative study has been made between square and circular section for different concrete mixes Nominal concrete (NC), Recycled aggregate concrete (RAC), high performance concrete (HPC)). The effectiveness and act regarding Stress strain, load deflection behavior, collapse pattern are studied in investigational models and resemblance with mathematical model which is done in ANSYS workbench module. In order to avoid degradation due to environmental effects Anti-corrosion agent is used while fabrication.

In order to solve the problems of rolling forming accuracy and fillet thinning of alloy steel rim, a three-dimensional model of three pass rolling process was established, and the influence of different process parameters on forming quality was analyzed by using the finite element software, and the optimal process parameter combination was obtained. On this basis, the simulation results of wheel rim stress and strain for each pass rolling are analyzed, and the particle tracking technology is introduced to analyze the variation rule of stress in each incremental step. Finally, the simulation and experimental results show that the simulation thickness is basically consistent with the actual thickness, which improves the accuracy of rim rolling forming, and further verifies the correctness of rolling process simulation.

Stress-Strain relations are graphical measures to determine the mechanical properties and morphology of engineering materials. In engineering universities, stress-strain curves are introduced in the introductory course of materials science for the mechanical, metallurgical and civil engineers. Stress-strain diagrams can be easily plotted from experimental data obtained from the uniaxial tensile testing of specimens made as per standards of engineering material. However, understanding of the metal’s deformation, dislocation behaviour, as well as the microstructure, is considered challenging. Common teaching aids present stress-strain diagrams as a working tool but does not explain how to relate various attributes like microstructural characteristics and mechanical behaviour with its engineering properties. This accumulated difficulty leads to a decreased level of motivation among first-year engineering students. The article presents CC maps an instructional strategy to gain sustainable knowledge on how to read stress-strain characteristics, interpret engineering properties and promote cognitive transfer in learning. The results obtained indicated that intervention of CC maps has improved conceptual understanding, learning interest and performance of students in the class.

The paper presents the review and evaluation of the containment prestressing system within reinforced concrete structures under seismic loads and severe accidents. Given the complex design of the containment, the detailed finite element model has been developed and used to describe real containment behavior. Containment stress and strain state was calculated by modern LIRA software. The first stage analyzed the results of WWER-1000/320 containment stress and strain state calculation under a combination of loads caused by maximum design basis accident (MDBA) and safe shutdown earthquake (SSE) and defined minimum acceptable tension of tendons. The research determines the minimum acceptable tension of tendons in the containment prestressing system, and evaluates the strength and reliability of containment structures under a combination of loads in normal operation + design-basis accident + maximum design earthquake (NO + DBA + MDE). The verification calculations have been performed using tendon tension of 780 ton-force in the cylindrical part of the containment and 760 ton-force in the containment dome. The second stage covered the analysis of severe accident parameters (pressure and temperature) and the results of calculation. Stress and strain state in ZNPP-1 containment has been calculated, parameters (pressure and temperature) under which the containment can loss its protective and isolation functions have been identified, calculation results have been analysed and conclusions of containment structural integrity and ensuring the implementation of the design confining functions have been made. Based on the calculation results, it can be concluded that strength of the containment cylindrical part during a beyond design-basis accident cannot be ensured under parameters t (temperature) = 120°С, p (pressure) = 0.6 MPa.

Wooden-composite plate-ribbed bent panels with structural plywood and oriented strand board sheathing with breaks are considered. An overview of studies researching and improving the effectiveness of different types of panels is presented. On the basis of the theory of calculation of composite rods by A.R. Rzha- nitsyn, a mathematical model has been compiled, which makes it possible to calculate the stress-strain state of these structures, taking into account the pre- sence of breaks in the sheathing and the flexibility of the mechanical fasteners of the sheathing and ribs. An equation for finding the coordinates of the most dangerous section of wooden ribs in the presence of breaks in the sheathing, which may not match with the middle of the span, is obtained. Panels with sheathing in a compressed zone with different locations of joints, symmetrically relative to the middle of the panel span are considered. Panels without joints in the skin are considered to compare the results. The graphs of the dependence of the maximum tensile stresses in the ribs in the most dangerous section and the maximum vertical displacements from the stiffness coefficient of the shear ties and the location of the breaks in the sheathing are presented. The values of the coefficients for the engineering design of panels, taking into account the decrease in the strength and deformation characteristics of the composite section of panels with breaks in the sheathing, as compared to panels with a solid sheathing, are obtained. The conclusions and recommendations, based on the results of the investigations, which can be used in the design of wooden-composite plate-ribbed structures, are formulated.

"During the shipbuilding processes carried out in the shipyards, there is a need to transport the sections of ship structure, from the place where they are built to the assembly location. When the shape and structure of the sections allow, they are built in an inverted position, and after finishing all the works that can be performed in this type of placement, the section will have to be turned to continue the section building process and subsequent the assembly. Loads that appear in the structure during these maneuvers are different from those that appear during the operation and from those for which calculations were made at the stage of the initial project. Therefore, it is necessary to calculate them and design a lifting / turning installation, which should also contain stiffening elements where required, in order to prevent both accidents and deformations or detachments that could occur at the section level. From this necessity appears the plan generically called ""lifting plan"" and which contains the installations, the schemes, the necessary instructions to remove the units from the section building hall, turn it to the gantry cranes and brought into the mounting position."