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The present work is the subject of an identification of the viscoelastic behavior of olive wood in creep. Creep bending tests are applied to a cantilever beam fixed at the left end and subjected to a concentrated load at its free end. The applied loads are sufficiently small that they cannot produce viscoplastic strain. A four-parameter viscoelastic model was adopted to reproduce the viscoelastic creep of wood. The elastic modulus is determined directly from the deflection creep curves. It increases with increasing load. The viscoelastic parameters of the studied model are identified using an inverse analysis technique. These parameters increase with increasing load. The test model creep curves show satisfactory consistency. [ABSTRACT FROM AUTHOR]

For bulk material it is very well known, that the material properties differ between the material near the surface and the inner material (i.e. segregations). However, for sheet material a gradient of material properties in depth direction and its influence on forming processes was not yet investigated. Within experiments on sheet steel 1.0338 (DC04) a gradient in material properties was proven by hardness measurements for both unprocessed material as well as after conducting forming and milling processes. The characterisation shows a gradient in material hardness over the entire sheet thickness. The experimental results regarding forming processes, such as rolling and bending, additionally show an increase of the materials hardness due to work hardening. The problem from the inhomogeneous material properties leads to an inaccurate prediction of the forming behaviour of the workpiece in further processing. Machining experiments were conducted for transferring the knowledge of modified surface and subsurface layers onto forming processes and their simulation. The bending experiments and the corresponding process simulation of the spring back behaviour show, that the implementation of an inhomogeneous material property increases the prediction accuracy. Notably the prediction of the spring back behaviour of thinner sheet metals is highly improved. Therefore, an analysis of sheet metal properties in thickness direction and their consideration in forming process simulations is inevitable for the implementation of accurate material models. [ABSTRACT FROM AUTHOR]

In this paper, the bending, buckling, and free vibration of functionally graded porous (FGP) beams are studied based on two beam theories (with or without considering thickness stretching, respectively). The effect of thickness stretching is obtained by comparing the results of the two theories. Two symmetrical distributions and one asymmetrical distribution of pores are considered. Both Young’s modulus and mass density of the FGP beams are in gradient variation in the thickness direction. The governing equations are constructed using Hamilton’s principle. The analytical solutions are obtained by Navier’s method. The effects of slenderness ratios, pore distribution, porosity and thickness stretching on FGP beams have been investigated. The results show that the inhomogeneity of FGP beams in the thickness direction is positively correlated with the effect of thickness stretching. [ABSTRACT FROM AUTHOR]

The study of cellular structures and their properties represents big potential for their future applications in real practice. The article aims to study the effect of input parameters on the quality and manufacturability of cellular samples 3D-printed from Nylon 12 CF in synergy with testing their bending behavior. Three types of structures (Schwarz Diamond, Shoen Gyroid, and Schwarz Primitive) were selected for investigation that were made via the fused deposition modeling technique. As part of the research focused on the settings of input parameters in terms of the quality and manufacturability of the samples, input parameters such as volume fraction, temperature of the working space, filament feeding method and positioning of the sample on the printing pad were specified for the combination of the used material and 3D printer. During the experimental investigation of the bending properties of the samples, a three-point bending test was performed. The dependences of force on deflection were mathematically described and the amount of absorbed energy and ductility were evaluated. The results show that among the investigated structures, the Schwarz Diamond structure appears to be the most suitable for bending stress applications. [ABSTRACT FROM AUTHOR]

Predicting a component's fatigue life requires information on not only the number of stress cycles the component will undergo but also the kind and frequency of those stress cycles, as well as information about the surrounding environment and the intended purpose of the component. Models that can forecast lifespan by utilizing available experimental data are preferred since fatigue investigations are costly and time-consuming. Therefore, this work focuses on fatigue testing of S355 mild steel specimens under multiaxial loading conditions involving bending and torsion. The impact of phase-shifted loading conditions on material behavior, considering in-phase and with angles 0°, 45°, and 90°, has been studied. Then, the data of fatigue tests involve variations in loading amplitudes, and configurations used in different ML algorithms such as lazy k-nearest neighbors (Lazy-KNN), linear regression (LR), and random forest (RF) were employed for predictive modeling. These models are evaluated based on their ability to predict nominal stresses, torsion, and bending moments under varying loading configurations. The predictive modeling results are visually presented, showcasing the effectiveness of Lazy-KNN in accurately predicting material responses. Quantitative analyses further confirm the robustness of Lazy-KNN in predicting bending, nominal stress, and torsion under different loading conditions. The study provides valuable insights into the fatigue behavior of S355 mild steel and highlights the significance of considering multiaxial loading configurations in material testing and design. [ABSTRACT FROM AUTHOR]

The paper presents a critical review and new accomplishments on the equivalence of the first-order displacement-based zigzag theories for laminated composite and sandwich structures. Zigzag theories (ZZTs) have widely spread among researchers over the last few decades thanks to their accuracy in predicting the response of multilayered composite and sandwich structures while retaining the simplicity of their underlying equivalent single-layer (ESL) theory. The displacement field consists of two main contributions: the global one, able to describe the overall structural behaviour, and the local layer-wise one that considers the transverse shear continuity at the layer interfaces that describe the "zigzag" displacement pattern typical of multilayered structures. In the framework of displacement-based linear ZZTs, various assumptions have been made on the local contribution, and different theories have been deduced. This paper aims to provide a unified formulation for first-order ZZTs, highlighting some common aspects and underlying equivalencies with existing formulations. The mathematical demonstrations and the numerical examples prove the equivalence of the approaches to characterising local zigzag enrichment. Finally, it is demonstrated that the kinematic assumptions are the discriminants of the ZZTs' accuracy. [ABSTRACT FROM AUTHOR]

Demand for bent pipe profiles in various industrial sectors is increasing due to considerations necessitating lightweight construction, safety, as well as space and cost savings. Lightweight construction is becoming increasingly important for economic and ecological reasons. This can be seen in the automotive and aerospace industries, as well as in civil engineering, where curved structures are often required. In order to reduce the weight of the aircraft, the aviation industry often uses spatial truss structures with bent elements. The challenge is to meet all of the stringent requirements regarding design, safety, structure, size, cost, etc., without compromising a structure's stiffness. Profiles with complicated cross-sections and so-called tailored tubes are increasingly used in the production of automotive and aircraft structures (General Aviation). Pipe and profile bending technologies are constantly being improved upon to meet the growing expectations of customers and ensure greater process efficiency. Currently, efforts are being made to increase the level of automation in this area by combining the functionality of modern bending machines with the capabilities of industrial robots. CNC bending machines currently dominate the industrial pipe bending process. A technologically advanced bending machine allows for the production of increasingly complex shapes and profiles. [ABSTRACT FROM AUTHOR]

Copper alloys are extensively used in the manufacture of electrical and electronic components, which strength depends on the material mechanical properties, which in turn depend on the metallurgical state. Even though the mechanical properties remain within the specifications, the subsequent formability limits may depend strongly on the material batch. Considering the forming stage to manufacture plug-in type connectors made of CuSn6P thin sheets, a crack may appear in the components, in the bent area subject to high strains, when changing the material batch. The aim of this study is to take account of these variations of the mechanical behavior through a probabilistic approach, to predict the formability limit. The mechanical properties of the materials from the two batches were characterized in tension, to highlight the differences. The initial yield stress and the tensile strength are higher for one material, while the maximum equivalent plastic strain at rupture, determined through a hybrid experimental-numerical approach, is lower. And a significant difference in the transverse anisotropy coefficient is evidenced. A 3D parametric finite element model of the forming stage is developed to investigate the role of some mechanical properties and process parameters on the formability limit in bending. The range of the parameter values comes from the experimental data. Their influence is evaluated through a design of experiments, with the aim of highlighting the influence of the variations of the mechanical properties and process parameters on the fracture criterion, using a probabilistic approach with Gauss’s law. [ABSTRACT FROM AUTHOR]

This paper presents a simple refined plate theory (S-RPT) which contains only three unknown variables in the displacement field for bending and buckling analysis and only one unknown variable in the displacement field for free vibration analysis. Unlike other simplified plate theories, S-RPT in its simplification (1) takes into account the Poisson's ratio variation along the thickness direction (2) takes into account the full coupling of in-plane and transverse displacements. These features make S-RPT applicable to the analysis of bending, buckling, and free vibration of functionally graded porous plates reinforced with graphene platelets (FGP–GPLs). Some simplified plate theories already available in the literature can be regarded as special cases of S-RPT. The S-RPT is first used in isotropic and metal–ceramic functionally graded plates to verify its accuracy. Then, the effect of pore distribution, GPLs distribution, porosity coefficient, aspect ratio, thickness ratio, and GPLs weight fraction on the bending, buckling, and free vibration behaviors are investigated based on S-RPT. [ABSTRACT FROM AUTHOR]

The present article explores static bending and natural oscillation characteristics of double-layer non-uniform thickness functionally graded (FG) plates that are equipped with shear connectors. The fundamental equations are comprehensively described and developed by the utilization of the finite-element method (FEM), in conjunction with the widely recognized and straightforward first-order shear deformation plate theory (FSDT). The current hypothesis and computational framework have been validated through a comparative analysis of the numerical findings from this study with those reported in other esteemed publications. Parametric research is undertaken to explore the impact of geometrical and physical features on the structural response of the FG plate, with particular emphasis on the variation in thickness and distribution of shear connectors. The numerical findings obtained from this study can serve as a valuable point of reference for further orientation endeavors in the same domain. Furthermore, the proposed complex structural model can be referred to as an important idea for application in the fields of aerospace, nuclear, and military technology. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach for assessing the uncertainty in vibration and static responses of laminated composite beams resulting from uncertainty in material properties and distributed loads. The proposed method utilizes surrogate models developed using polynomial chaos expansion (PCE) based on a relatively small sample size. These training samples are computed using a high-order shear beam model in which the governing equations are derived using Hamilton's principle, and solved by Ritz's approach using a trigonometric series approximation. The proposed PCE model's coefficients are estimated using the spectral projection and linear regression techniques. The first four statistical moments and probability distributions of the mid-span displacement and the fundamental frequency of laminated composite beams are predicted. Global sensitivity analysis is also conducted to assess how material property variation and stochastic loads affect the beam's deflection and the fundamental frequency. The accuracy and efficiency of the proposed PCE models are compared with those from Monte Carlo simulation (MCS). A remarkable reduction in the computational cost of PCE models compared to MCS is observed without compromising the predictions' accuracy. As most real-world systems are subjected to multiple sources of uncertainty, this study provides a state-of-the-art method to quantify such uncertain parameters more efficiently and allow for a better reliability assessment in composite beam design. [ABSTRACT FROM AUTHOR]

In the companion paper, test results were presented to explore the flexural performance of cold-formed ferritic stainless steel (FSS) closed built-up beams. Each specimen was fabricated by joining two lipped channels in a face-to-face configuration and securing them with spot welds at intermediate points along the beam span. Sectional aspect ratio, compression flange's sectional slenderness and moment gradient were the key parameters varied to explore their influence on the flexural response of such members through tests. The current paper establishes a simplified finite element (FE) model of cold-formed FSS closed built-up beams and verifies it against the test results. Further, an extensive parametric study is carried out using the validated FE model to generate a large pool of data points. A wider database comprising of test results, numerical results obtained from this study and numerical results available in the companion paper were used to critically examine the adequacy of the current Australian Specifications (AS/NZ), American Standard (SEI/ASCE-8), European Code (EN 1993-1-4), Modified Eurocode approach suggested by Gardner and Theofanous, and Direct Strength Method (DSM) in North American Specification (AISI-S100: 2016), Modified DSM approach proposed by the authors in the literature and Continuous Strength Method (CSM) for cold-formed steel (CFS) flexural members. This makes the current study the first to extensively assess the accuracy of the various design guidelines available in the codes and other relevant literature, which explicitly highlighted their grave limitations. Accordingly, through suitable modifications and recommendations, new design rules are proposed to reliably and safely predict the flexural capacity of cold-formed FSS closed built-up beams. [ABSTRACT FROM AUTHOR]

Based on higher-order shear deformation theory (HSDT), the bending of China Railway Track System type II (CRTS-II) track laminated plates on elastic foundations and interlayer shearing performances are analyzed by meshfree radial point interpolation method (RPIM), which has the properties of the Kronecker function and discretizes the governing equations derived from HSDT. To verify the applicability of the model, the geometric configuration and key parameters of the CRTS-II slab ballastless track structure are analyzed, and the interlaminar slip model of the track structure is derived as a benchmark solution when calculating the track structure using HSDT-RPIM. The accuracy of the derivation is verified by comparing the HSDT-RPIM model with a double-layer slab model considering bidirectional interlayer slip. Then, the effect of resistant slip coefficient on the bending deformation of the track structure was analyzed using the bidirectional interlaminar slip model. The effect of elastic foundation coefficient on the bending of the track structure and the interlayer slip of the track structure (track slab – base slab) was analyzed. Finally, the effects of boundary conditions and elastic foundation coefficients on the interlaminar stresses of the track structure are investigated using HSDT-RPIM, and some interlaminar damages of the track structure are explained. It is for the first time that the CRTS-II track composite slab was newly model by high-order shear deformation and laminated theory, which is of great progress on the composite structures of CRTS-II track slabs. The HSDT-RPIM theory can be used to consider both symmetric and asymmetric laminates in the thickness direction. The interlaminar forces and slip between the layers of the CRTS-II track structure are analyzed and validated with experiments. [ABSTRACT FROM AUTHOR]

In this study, a new mixed-field zigzag shell model is proposed in terms of Reissner's Mixed Variational Theorem (RMVT) for the composite laminates with curvature. In this model, refined zigzag theory (RZT) is employed to improve the accuracy and efficiency by introducing through-the-thickness piecewise linear warping functions. Moreover, the shear correction factors are eliminated. It is also different from the published models for composite laminated shells, the continuity conditions of interlaminar transverse shear stresses (TSSs) are satisfied a priori based on RMVT. The equilibrium equations and related boundary conditions are also derived from RMVT. Subsequently, the static performance, natural frequencies, and critical loads of composite laminates with curvature are verified by comparing them with the 3D elastic solutions and other existing ones. It is observed that the present model accounts for not only the efficiency of the low-order models but also the accuracy of the high-order models. Finally, it is shown that the ply stacking, side-to-thickness ratios, and side-to-radius ratios play an important role in percentage errors between the present model and the previous ones. [ABSTRACT FROM AUTHOR]

This article considers a bidirectional functionally graded (BDFG) beam with various distributions of volume fraction. The impact of these distributions on the buckling and bending response of BDFG beam with general boundary conditions is investigated via a quasi-3D solution. It is assumed that the beam is exposed to a set of in-plane varying compressive loads and there mechanical characteristics change in both directions. Also, the BDFG beam is considered to be exposed different external mechanical loads. Hamilton's principle is employed to derive the governing equations, which are then solved using analytical solution to obtain buckling and bending characteristics. The precision of the current formulation is investigated via a comparison with available data in literature. Some numerical results are presented and discussed to assess the effect of different parameters such type of volume fraction, boundary condition, varying load, and beam geometry on the buckling and bending of BDFG beam. [ABSTRACT FROM AUTHOR]

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Introduction: Electrical transmission lines are normally composed of large spans that have large displacements and are subject to complex three-dimensional motions. The dynamic behavior can be analyzed through non-linear mathematical models obtained by the finite element method that can be validated by experimental data. Materials and Methods: The analyses consisted of obtaining experimental data for two different tests, bending and torsion, using accelerometers placed along samples of three different cables and with varying mechanical tension. The experimental data were compared with numerical data obtained by computer simulation of mathematical models obtained by the finite element method and using 3d frame elements. For the bending tests, the natural frequencies of the first five modes of vibration were compared and for the torsion tests, the torque angle was compared. Data were adjusted using the particle swarm optimization method (PSO). Results: For all situations analyzed (different cables, tensile loads and positioning of sensors and excitation) an excellent agreement between numerical and experimental values was noted. For bending tests, numerical and experimental values of the first five natural frequencies were compared using PSO method. Differences lower than 0.5% were noted for low loading values where the nonlinear behavior of the first modes is evident. The torsional behavior was analyzed using a bench containing a lever manually excited. By minimizing a function taking into account the difference between numerical and experimental values of the twist angle, the shear modulus is adjusted using PSO method. For all situations, it was possible to obtain good agreement between numerical and experimental values of the twist angle with deviation lower than 1%. Conclusions: It was evident that the non-linear mathematical model presented good results for both the bending and torsion tests. The differences between numerical and experimental values were small with rapid convergence using the PSO method. The proposed methodology for torsion tests using a manually operated lever proved to be efficient for adjusting torsional stiffness. It was noted that the shear modulus is influenced by the position of the lever and direction of the torsion. [ABSTRACT FROM AUTHOR]

Purpose: This paper proposes a novel shear deformation theory to study the static bending and buckling of nanoplates subjected to flexomagnetic influence. This is done using the revolutionary shear strain theory and establishing finite element formulations based on the finite element technique. Methods: This study uses a finite element method to solve the nanoplate bending and buckling problem while taking into consideration the flexoelectromagnetic effect. Results: The investigation's novel aspects are summarized: since the flexomagnetic effect makes the plate stiffer, the maximum deflection is lowered when this effect is included. This effect also has varying influences on the plate under various boundary conditions, particularly the maximum position of the deflection, stress, Hz, and Bz responses. The thinner the plate thickness, the more pronounced the flexomagnetic effect. The flexomagnetic effect causes the thickness distribution of the stress components, Hz, and Bz to diverge from that of conventional structures (where this effect is disregarded), particularly for plates with CFFF boundary conditions. The longer the length of the compression zone increases, the lower the critical buckling load of the plate. The greater the stiffness of the elastic foundation, the better the plate can withstand compressive loads. Conclusion: The findings of this work provide a significant scientific foundation for the computation and development of nanoplates with magnetic properties. To design a structure that meets the necessary criteria, it is crucial to carefully choose geometric characteristics, boundary conditions, and stiffness parameters of the elastic foundation. According to this study, potential areas for additional research include investigating the impact of the flexomagnetic effect on nanoplates including fractures, optimizing nanostructures that exhibit flexomagnetic effects, and calculating the influence of flexomagnetic effects and temperature on nanostructures. [ABSTRACT FROM AUTHOR]

Mechanically lined pipe (MLP) is often used for offshore oil and gas transport because of its low cost and corrosion resistance. During installation and operation, the pipe may undergo severe bending deformation, which causes the liner to separate from the outer pipe and buckles, affecting the stability of the whole line. In this paper, the buckling response of MLP subjected to bending is investigated to clarify its bending characteristics by employing both experiments, numerical simulation, as theoretical methods. Two types of MLPs were manufactured with GB 45 carbon steel (SLP) and Al 6061 (ALP) used as the outer pipe material, respectively. The hydraulic expansion and bending experiments of small-scale MLPs are conducted. In addition to the ovalized shape of the cross-section for the SLP specimens, the copper liner was found to wrinkle on the compressive side. In contrast, the liner of ALP remains intact without developing any wrinkling and collapse mode. In addition, a dedicated numerical framework and theoretical models were also established. It was found both the manufacturing and bending responses of the MLP can be well reproduced, and the predicted maximum moment and critical curvatures are in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

This study is centered on examining the static bending behavior of sandwich plates featuring functionally graded materials, specifically addressing distinct representations of porosity distribution across their thickness. The composition of the sandwich plate involves a ceramic core and two face sheets with functionally graded properties. Mechanical loads with a sinusoidal distribution are applied to the sandwich plate, and a four-variable shear deformation theory is employed to establish the displacement field. Notably, this theory involves only four unknowns, distinguishing it from alternative shear deformation theories. Equilibrium equations are derived using the virtual work concept, and Navier's method is applied to obtain the solution. The study addresses the impact of varying porosities, inhomogeneity parameters, aspect ratios, and side-to-thickness ratios on the static bending behavior of the sandwich plates. The influence of various porosities, inhomogeneity parameter, aspect ratio, and side-to-thickness ratio of the sandwich plates are explored and compared in the context of static bending behavior. The three porosity distributions are compared in terms of their influence on the bending behavior of the sandwich plate. The findings indicate that a higher porosity causes larger deflections and Model A has the highest central deflection. Adopting the four-variable shear deformation theory demonstrated its validity since the results were similar to those obtained in the literature. Several important findings have been found, which could be useful in the construction and application of FG sandwich structures. Examples of comparison will be discussed to support the existing theory's accuracy. Further findings are presented to serve as benchmarks for comparison. [ABSTRACT FROM AUTHOR]

Demand for bent pipe profiles in various industrial sectors is increasing due to considerations necessitating lightweight construction, safety, as well as space and cost savings. Lightweight construction is becoming increasingly important for economic and ecological reasons. This can be seen in the automotive and aerospace industries, as well as in civil engineering, where curved structures are often required. In order to reduce the weight of the aircraft, the aviation industry often uses spatial truss structures with bent elements. The challenge is to meet all of the stringent requirements regarding design, safety, structure, size, cost, etc., without compromising a structure's stiffness. Profiles with complicated cross-sections and so-called tailored tubes are increasingly used in the production of automotive and aircraft structures (General Aviation). Pipe and profile bending technologies are constantly being improved upon to meet the growing expectations of customers and ensure greater process efficiency. Currently, efforts are being made to increase the level of automation in this area by combining the functionality of modern bending machines with the capabilities of industrial robots. CNC bending machines currently dominate the industrial pipe bending process. A technologically advanced bending machine allows for the production of increasingly complex shapes and profiles.

In this work, multilayer graphene was chosen and modeled in ANSYS software. In the software, it was subjected to bending forces through various bend angles. In order to test for bending, the model is subjected to rigid support on the base side. Then a force is applied on the side on which the angle is provided to simulate Bending. Stress–strain plots were analyzed for various bending angles. The graphene sheet was also subjected to twist forces within the software. In order to test for torsion, the model is subjected to rigid support on both sides. Then a couple is applied on the opposite sides to simulate torsion. Torsional stress and strain measurements were analyzed. The trends were studied and correlations with the material properties of graphene were established. The quest is to identify a magic angle for bend and twist. [ABSTRACT FROM AUTHOR]

The flexural behavior of hybrid timber–steel encased beams comprising coniferous radiata pine (Pinus radiata) (MGP10) and Douglas fir (Pseudotsuga menziesii) (F8) timber lamellae with bonded-in steel bars is studied. The effect of cross-section depth, steel bar size, timber species/grade, and steel bar arrangements (only bottom and top-and-bottom) on the hybrid beams' stiffness, failure mode, ductility, and load-carrying capacity were investigated. The flexural capacity and stiffness of the doubly (top-and-bottom) reinforced beams are increased by 127% and 71%, respectively. However, in the singly (bottom) reinforced beams, the flexural capacity and stiffness are increased only by 41% and 25%, respectively, highlighting the important role of the compressive bars. The failure of all beams was associated with tensile flexural failure of timber, but the steel bars improved the ductility of the beams. The maximum coefficient of variation of the peak load in hybrid beams (CoV=14.3%) is lower than that of the bare timber beams (CoV=21.7%). Two analytical models were developed based on a linear and a bilinear stress–strain relationship for timber. The analytically predicted peak load and stiffness agree well (less than 13% and 12% difference) with the experimental results. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the feasibility of using yellow poplar as a structural member by determining allowable bending properties. Full-size lumber was classified by machine grading and the knot diameter ratio on the wide surface of lumber. The majority of machine grades of yellow poplar lumber with a cross-section of 38 × 89 mm2 were E8, E9, and E10. It was confirmed that the size of the knot diameter ratio tended to be smaller for higher machine grades. In the lowest grade, E8, of most machine grades, the allowable bending strength was lower than the corresponding design value in Korean standards. Application of 0.5 knot diameter ratio to the E8 grade lumber increased the bending strength to 3 MPa of the allowable value to suit the design value. All the allowable modulus of elasticities values of the majority of machine grades were higher than the design values. From the results of this study, it was expected that Korean yellow poplar could be utilized for structural bending members.

This study investigates the effect of characteristics and distribution of Mg17Al12 precipitates on the uniaxial tensile and three-point bending properties of extruded Mg alloys containing high Al contents. The extruded Mg–9Al–1Zn–0.3Mn (AZ91) alloy contains lamellar-structured Mg17Al12 discontinuous precipitates along the grain boundaries, which are formed via static precipitation during natural air cooling. The extruded Mg–11Al–1Zn–0.3Mn (AZ111) alloy contains spherical Mg17Al12 precipitates at the grain boundaries and inside the grains, which are formed via dynamic precipitation during extrusion. Due to inhomogeneous distribution of precipitates, the AZ111 alloy consists of two different precipitate regions: precipitate-rich region with numerous precipitates and finer grains and precipitate-scarce region with a few precipitates and coarser grains. The AZ111 alloy exhibits a higher tensile strength than the AZ91 alloy because its smaller grain size and more abundant precipitates result in stronger grain-boundary hardening and precipitation hardening effects, respectively. However, the tensile elongation of the AZ111 alloy is lower than that of the AZ91 alloy because the weak cohesion between the dynamic precipitates and the matrix facilitates the crack initiation and propagation. During bending, a macrocrack initiates on the outer surface of bending specimen in both alloys. The AZ111 alloy exhibits higher bending yield strength and lower failure bending strain than the AZ91 alloy. The bending specimens of the AZ91 alloy have similar bending formability, whereas those of the AZ111 alloy exhibit considerable differences in bending formability and crack propagation behavior, depending on the distribution and number density of precipitates in the specimen. In bending specimens of the AZ111 alloy, it is found that the failure bending strain (εf, bending) is inversely proportional to the area fraction of precipitates in the outer zone of bending specimen (Appt), with a relationship of εf, bending = –0.1Appt + 5.86.

Aiming at the problem that large sheet metal bending parts cannot be processed by single robot, and the manual assisted bending method has high labor intensity and low work efficiency; double robots work together to complete the handling of the plate; Firstly, according to the actual production requirements of sheet metal bending, the process planning and three-dimensional modeling of the production line are completed. Secondly, the kinematics analysis and base coordinate system calibration of the dual robot are completed. Then, by establishing the mathematical model of each unit, the end pose matrix in the local coordinate system of the robot is finally obtained, and the joint angles of the robot machine are obtained by inverse kinematics. Finally, the production line simulation is completed by Rapid offline programming. The research results show that the kinematics model is correct, and the production line can complete the sheet metal bending work without collision, which can provide reference for the research of large sheet metal bending.

Introduction/purpose: This article presents the bending examination of advanced-generation composite structures with specific properties exposed to different loads. Methods: This paper thus proposes and introduces a new generalized five-variable shear strain theory for calculating the static response of functionally graded rectangular plates made of ceramic and metal. Notably, our theory eliminates the need for a shear correction factor and ensures zero-shear stress conditions on both the upper and lower surfaces. Numerical investigations are introduced to interpret the influences of loading conditions and variations of power of functionally graded material, modulus ratio, aspect ratio, and thickness ratio on the bending behavior of FGPs. These analyzes are then compared to the results available in the literature. Results: Preliminary results include a comparative analysis with standard higher-order shear deformation theories (PSDPT, ESDPT, SSDPT), as well as Mindlin and Kirchhoff theories (FSDPT and CPT). Conclusion: Our theory contributes alongside established theories in the field, providing valuable insights into the static thermomechanical response of functionally graded rectangular plates. This encompasses the influence of volume fraction exponent values on non-dimensional displacements and stresses, the impact of aspect ratios on deflection, and the effects of the thermal field on deflection and stresses. Numerical examples of the bending examination of advanced-generation composite structures with specific properties exposed to different loads demonstrate the accuracy of the present theory.

A novel approach to monitor the degree of bending via flexible photonics devices, using ratiometric power variation in a few-mode optical waveguide, is proposed. To demonstrate its feasibility, a sensor exploiting a Bragg grating, approximately aligned to the neutral axis, is designed, fabricated and characterized. The reduced thickness of the proposed planar photonic sensor is uniquely limited by optical confinement requirements, enabling for an ultra-thin and highly flexible planar device, based on all-glass platform. Finite Element Method, Beam Propagation Method and Coupled Mode Theory are employed in the design to model the electromagnetic and mechanical phenomena occurring during the three-point bending test. The experiment demonstrates that the planar device withstands tight curvature without mechanical failure. The device shows that by increasing the bending the reflected power from the fundamental mode decreases and the reflected power from the higher order mode increases. The measured ratiometric power sensitivity versus displacement is $K_{P_{R}}=-0.78 \mathrm {dB/mm}$ with negligible variation over a 40°C thermal range. Therefore, exploiting both the Bragg wavelength shift and the mode optical power change, the proposed sensor can be employed for multiparameter sensing purposes, e.g. simultaneous temperature and curvature monitoring.

The study focused on the potential use of agricultural waste (corn cob) in the manufacturing of composite materials. In the first stage, composite materials were manufactured and tested using synthetic matrices (epoxy and acrylic) and hybrid matrices based on dammar resin (50% dammar, 60% dammar, and 70% dammar). Since it was observed that the samples had low mechanical properties under tensile and bending loads, the study was expanded to the production of sandwich-type composites with silk fabric facings. It was found that, by utilizing silk fiber, both tensile and bending strength increased from a few hundred percent up to a few thousand percent, compared to the samples that are only reinforced with crushed corn cob.

Highlights Drilling glass fiber reinforced polymer matrix (GFRP) composites typically causes burrs, splintering, and microcracks within the GFRP structure, as well as delamination, fiber pull‐out, and thermal degradation of the polymer matrix. Designing and manufacturing molded‐hole GFRP components, as opposed to drilling, has recently been proposed as a promising method for overcoming the issues associated with drilling, for which there is limited research. Specifically, the mechanical response of molded‐hole GFRP has not been fully addressed in the literature. In the present study, molded and drilled GFRP composites with epoxy matrix were fabricated by hand lay‐up, and then the samples were analyzed utilizing experimental and numerical analysis techniques. Stress and strain analyses of GFRP samples were performed in Ansys Transient Structural Analysis. Although the fiber orientations of the layer geometries [0°/90°] and 3D models were the same, an additional layer was defined in the direction of the fiber orientation [45°/−45°] of molded‐hole composites to simulate the fiber accumulation effect. Experimental findings revealed that the flexural strength of molded composites was 12% greater than that of drilled composites. According to the numerical analysis, 98.7% proximity was achieved between the experimental and numerical results. Thus, the present study has provided numerical modeling to understand the flexural strength of molded composites for the first time, which will contribute to the increased use of molded composites in numerous applications in the fields of aerospace, automotive, and marine. Drilled‐ and molded‐hole GFRP composites were produced by hand lay‐up. Flexural properties of the composites were examined via 4P bending tests. Flexural strength of molded composites was higher than that of drilled ones. 98.7% proximity was achieved between the experimental and FEM results. A unified FEM method is proposed for the molded‐hole composites. [ABSTRACT FROM AUTHOR]

The flexible memristor synapses based on binary metal oxides have significant potential in building artificial neural networks to meet people's demands. To obtain flexible memristor synapses with high linearity of conductance update, herein, the effect of Al doping and SiOx layer adding on the flexible TiOx‐based memristor synapse even under bending is studied. The results show that the doping Al and adding SiOx layer improves the linearity of conductance update by 3 times. The bending test results of the SiOx/Al:TiOx‐based memristor synapse show that the linearity decreases slightly with the decrease of the bending radius. When the bending radius is reduced to 5 mm, the total nonlinearity (NL) value of the device is about 0.42. It is still much smaller than the total NL value of TiOx‐based memristor synapse in flat state (about 0.76). The test results of conducting atomic force microscopy show that the improvement of linearity is due to the optimization of conductive filaments. The results provide a feasible program for improving linearity of TiOx‐based flexible memristor synapse even under bending, which can support for the development of high‐performance binary metal oxide flexible memristor synapse. [ABSTRACT FROM AUTHOR]

The bending analysis of isotropic, laminated composite and cylindrical sandwich shells was carried out using a higher order shear deformation theory which incorporates undetermined integral in the displacement field. The model proposed involves only four variables. Moreover, unlike the conventional FSDTs, the shear correction factor is not necessary. The Hamilton's principle and the Navier's method are employed to determine and solve the equations of motion. The present analytical model was compared with other higher-order theories in the literature. In addition, finite element analysis methods were designed to calculate displacements and stresses of shells. Shells are subjected to uniform loads. Results are given for shallow and deep shells and thick to thin. According to the analysis, kinematics, based on the indeterminate integral component, are very effective and enable researchers to investigate laminated plates and shells more accurately than traditional models. [ABSTRACT FROM AUTHOR]

Picking objects off the floor is provocative for people with chronic low back pain (CLBP). There are no clinically applicable methods evaluating movement strategies for this task. The relationship between strategy and multidimensional profiles is unknown. Develop a movement evaluation tool (MET) to examine movement strategies in people with CLBP (n = 289) picking a pencil off the floor. Describe those movement strategies, and determine reliability of the MET. Explore differences across multidimensional profiles and movement strategies. An MET was developed using literature and iterative processes, and its inter-rater agreement determined. Latent class analysis (LCA) derived classes demonstrating different strategies using six movement parameters as indicator variables. Differences between classes across multidimensional profiles were investigated using analysis of variance, Kruskal-Wallis, or chi-squared tests. Six movement parameters were evaluated. There was substantial inter-rater agreement (Cohen's Kappa = 0.39–0.79) across parameters. LCA derived three classes with different strategies: Class 1 (71.8%) intermediate trunk inclination/knee flexion; Class 2 (24.5%) greater forward trunk inclination, lower knee flexion; Class 3 (3.7%) lower forward trunk inclination, greater knee flexion. Pain duration differed across all classes (p ≤.001). Time taken to complete forward bends differed between Class 3 and other classes (p =.024). Movement strategies can be reliably assessed using the MET. Three strategies for picking lightweight objects off the floor were derived, which differed across pain duration and speed of movement. [ABSTRACT FROM AUTHOR]

The nonlinear deflection response of the sandwich shell panel with cutout is analyzed, numerically in the present article. The numerical model of the said curved panel is derived using higher-order shear deformation theory and finite element approximations. The geometrical nonlinearity is being considered via Green-Lagrange's strain-displacement relation. The governing equation of the nonlinear bending analysis is derived using the energy approach and variational principle. Model accuracy is analyzed as a first step by matching current model responses with previously available data. Further, the model's capability is explored by solving various new numerical examples and discussed in detail. [ABSTRACT FROM AUTHOR]

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