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Copyright of Journal of Engineering Sciences & Information Technology is the property of Arab Journal of Sciences & Research Publishing (AJSRP) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Packages made of corrugated paper are fundamental to the protection, transportation and handling of the appliance product market. During the storage and sales stages of a product, the package must resist compressive loads in different directions beyond moderate impacts. In this context, the objective of this work is to develop and implement a post-processor that allows the simultaneous analysis of two of the most common failure modes of packages made of corrugated paper: failure due to tensile or compressive stress limit, and failure due to local buckling, when the buckling of the faces of the corrugated paper between two peaks of the fluting waves occurs. It was realized that the current procedure proposed by the literature expend a series of operations, what became the failure analysis for corrugated boxes too lengthy for the immediacy of the industry. Thus, it was chosen to apply a procedure to simplify the failure limit surface. Tensile tests were performed for the characterization of corrugated material used in numerical simulations. Experimental tests were performed on corrugated boxes used on household appliance products. The Tsai-Wu criteria for the material failure evaluation was applied and a modified Nyman-Gustafsson criteria for the local buckling analysis on the numerical simulations was proposed. A good correlation between experimental tests and numerical results was obtained. This work brings high expectations to the agility requested by the industry in the launching of new products. [ABSTRACT FROM AUTHOR]

Polypropylene fiber reinforcement is an effective method to enhance the durability of concrete structures. With the increasing public interest in the widespread use of polypropylene fiber reinforced concrete (PFRC), the necessity of evaluating the mechanism of polypropylene fiber (PF) on the permeability of concrete has become prominent. This paper describes the influence of PF on the concrete permeability exposed to freeze-thaw cycles under compressive and tensile stress. The permeability of PFRC under compressive and tensile loads is accurately measured by a specialized permeability setup. The permeability of PFRC under compressive and tensile loads, the volume change of PFRC under compressive load, and the relationship between compressive stress levels at minimum permeability and minimum volume points of PFRC are discussed. The results indicate that the addition of PF adversely affects the permeability of concrete without freeze-thaw damage and cracks. However, it decreases the permeability of concrete specimens exposed to freeze-thaw cycles and cracking. Under compressive load, the permeability of PFRC initially decreases slowly and follows by a significant increase as the compressive stress level increases. This phenomenon correlates with the volume change of the specimen. The compressive stress level of the minimum permeability point and compressive stress level of the minimum volume point of PFRC exhibit a linear correlation, with a fitted proportional function parameter γ ≈ 0.98872. Under tensile load, the permeability of PFRC increases gradually with radial deformation and follows by a significant increase. The strain-permeability curves of PFRC under loading are studied and consist of two stages. In stage I, the permeability of PFRC gradually decreases with the increase of strain under compressive load, while the permeability increases with the increase of strain under tensile load. In stage II, under compressive load, the permeability of PFRC increases with the increase of freeze-thaw cycles, whereas under tensile load, the permeability gradually decreases with the increase of freeze-thaw cycles. The reduction of PF on the permeability of PFRC under tensile load is greater than that under compressive load. In future research, the relationship between strain and permeability of PFRC can be integrated with its constitutive relationship between stress and strain to provide a reference for the application of PF in the waterproofing of concrete structures. [ABSTRACT FROM AUTHOR]

This paper presents a mesoscale damage model for composite materials and its validation at the coupon level by predicting scaling effects in un-notched carbon-fiber reinforced polymer (CFRP) laminates. The proposed material model presents a revised longitudinal damage law that accounts for the effect of complex 3D stress states in the prediction of onset and broadening of longitudinal compressive failure mechanisms. To predict transverse failure mechanisms of unidirectional CFRPs, this model was then combined with a 3D frictional smeared crack model. The complete mesoscale damage model was implemented in ABAQUS®/Explicit. Intralaminar damage onset and propagation were predicted using solid elements, and in-situ properties were included using different material cards according to the position and effective thickness of the plies. Delamination was captured using cohesive elements. To validate the implemented damage model, the analysis of size effects in quasi-isotropic un-notched coupons under tensile and compressive loading was compared with the test data available in the literature. Two types of scaling were addressed: sublaminate-level scaling, obtained by the repetition of the sublaminate stacking sequence, and ply-level scaling, realized by changing the effective thickness of each ply block. Validation was successfully completed as the obtained results were in agreement with the experimental findings, having an acceptable deviation from the mean experimental values. [ABSTRACT FROM AUTHOR]

Lattice structures have emerged as promising materials for aerospace structure applications due to their high strength-to-weight ratios, customizable properties, and efficient use of materials. These properties make them attractive for use in anti-ice systems, where lightweight and heat exchange are essential. This paper presents an extensive experimental investigation into mechanical compression properties of lattice trusses fabricated from AlSi10Mg powder alloy, a material commonly used in casted aerospace parts. The truss structures were manufactured using the additive manufacturing selective laser melting technique and were subjected to uniaxial compressive loading to assess their performance. The results demonstrate that AlSi10Mg lattice trusses exhibit remarkable compressive strength with strong correlations depending upon both topology and cells' parameters setup. The findings described highlight the potential of AlSi10Mg alloy as a promising material for custom truss fabrication, offering customizable cost-effective and lightweight solutions for the aerospace market. This study also emphasizes the role of additive manufacturing in producing complex structures with pointwise-tailored mechanical properties. [ABSTRACT FROM AUTHOR]

Distributed nonstructural elements (NSEs), such as piping systems, are restrained against seismic actions using proprietary or, at times, custom-designed braces. The strengths of these elements are provided in the component brochures published by the manufacturers, with no information on their deformation capacities. Previous research on the seismic performance of NSEs provide several formulations to calculate possible reductions in design force by relying on ductility capacity of their seismic restraints. However, designers require a realistic estimate of the ductility capacity of the seismic restraints to use these formulations. This paper discusses the results of a test program on the behavior of brace assemblies under monotonic tensile and compression loading. The results are used to identify the potential failure modes of the tested brace assemblies and to quantify their ductility capacity. Further, design examples are presented to highlight the need for the use of capacity design principles in the design of brace assemblies and their anchors. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Petroleum Research & Studies is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Reinforced concrete interfaces, either cracks within monolithic elements or joints between concretes cast at different times may become critical under cyclic actions, due to stiffness and interface resistance degradation. Among the numerous parameters affecting the behavior of interfaces, this paper focuses on the effect of externally applied compressive stress. In conjunction with this parameter, the diameter of the reinforcing bars crossing the interface, their embedment length, and the anchorage of the interface reinforcement, by bond or using epoxy resin, are investigated. Roughened concrete interfaces crossed by reinforcing bars were subjected to cyclic shear slips, with or without compressive stress normal to the interface. The presented experimental results prove the beneficial effect of the external compressive stress on the ultimate shear resistance of interfaces, accompanied by the reduction of the effect of small embedment length of the interface reinforcement, due to its reduced contribution: the externally imposed compression leads to smaller crack openings at the interface, in most cases smaller than 0.40 mm, and to reduction of the reinforcement clamping effect. The shear resistance is activated at reduced shear slip values (0.20 mm–0.40 mm compared to 0.20–0.80 mm for interfaces under zero external compression), while the interface resistance degradation is also reduced (e.g., during the second load cycle, to 15% on average, compared to 30% for interfaces under zero external compression). Finally, an equation previously proposed by the authors is applied for the prediction of the shear resistance of interfaces under normal force, leading to satisfying accuracy. [ABSTRACT FROM AUTHOR]

In this paper, an analytical solution for exploring the buckling characteristics of functionally graded (FG) plate is presented based on a quasi-3D shear deformation theory. It is considered that the plate is subjected to different types of in-plane compressive load. The FG plate is placed on three-parameter foundation WinklerPasternak-Kerr. The overall material properties of FG plate are assumed to be varied across the thickness and are estimated through the Voigt micromechanical model. The governing equations are obtained on the base of the quasi-3D deformation theory that contain undetermined integral forms and involves only four unknowns to derive. Equations of motion are derived from the principal of virtual work and the analytical solution is used to determine the critical buckling loads. By the discussion of numerical examples and the comparison with those of the reports in the literature, the convergence and the reliability of the present approach are validated. Finally, the parametric investigations of the in-plane buckling are carried out, including the influence of boundary conditions, elastic foundation, plate geometric parameters and power law index. The results reveal that the critical buckling loads are strongly influenced by several parameters such as boundary conditions, elastic foundation parameters and geometric shape of the plate. [ABSTRACT FROM AUTHOR]

This paper experimentally investigates the influence of saturation on dynamic behaviors of concrete under both tension and compression stress states. Two grades of concrete were saturated to 0%, 50%, and 100% by oven drying and water soaking procedures. Split Hopkinson pressure bar (SHPB) tests, reaching the highest strain rate of about 170 s−1 , were carried out for dynamic compression. Dynamic splitting tensile tests were carried out by an Instron high-speed test machine, achieving the highest strain rate of about 40 s−1. The test results show that concrete specimens with different saturation ratios are all strain rate-sensitive. Under tensile loading, the effect of free on viscosity is only found to affect concrete's behavior when the strain rate is not very high. The strain rate sensitivity increases with water content when the strain rate is lower than about 3 s−1. However, when the strain rate is greater than 3 s−1 , strain rate sensitivity of concretes with different saturations become similar. Under compressive loading, free water in pores reduces the rate effect because it increases the hydrostatic pressure inside the specimen and leads to hydraulic fracturing. The microcracks caused by the hydraulic fracturing effect in the specimen result in macroscopic strength degeneration. [ABSTRACT FROM AUTHOR]

Interlocking Inter-Module Connections (IMCs) in Modular Steel Buildings (MSBs) have garnered significant interest from researchers. Despite this, the optimisation of plate thicknesses in such structures has yet to be extensively explored in the existing literature. Therefore, this paper focuses on optimising the thickness of interlocking IMCs in MSBs by leveraging established experimental and numerical simulation methodologies. The study developed various numerical models for IMCs with plate thicknesses of 4 mm, 6 mm, 10 mm, and 12 mm, all subjected to compression loading conditions. The novelty of this study lies in its comprehensive parametric analysis, which evaluates the slip prediction model. A random forest regression model, trained using the 'TreeBagger' function, was also implemented to predict slip values based on applied force. Sensitivity analysis and comparisons with alternative methods underscored the reliability and applicability of the findings. The results indicate that a plate thickness of 11.03 mm is optimal for interlocking IMCs in MSBs, achieving up to 8.08% in material cost reductions while increasing deformation resistance by up to 50.75%. The 'TreeBagger' random forest regression significantly enhanced slip prediction accuracy by up to 7% at higher force levels. [ABSTRACT FROM AUTHOR]

This article compares the two most used strain determination experimental techniques, the strain gauges and the digital image correlation (DIC), which are used here to determine the static Poisson's ratio of rock-like materials under a compressive loading. While the strain gauge technique measures the strains on the small patch of the underlying material on the spot, where the strain gauge is applied, DIC is a novel optical full-field technique that can measure the strains over the entire region of interest of the specimen. The key research question presented in this paper and research significance is to what extent the measurement of Poisson’s ratio is improved by leveraging the richness of the full-field measurements compared to the conventional strain gauge technique. To this purpose, the hypothesis was tested through virtual experiments in which a numerical simulation of a uniaxial compression test with a cylindrical, rock-like sample was created to mimic the strain gauge and DIC measurement techniques, as well as by conducting an actual compression test on a sandstone material. In contrast to conventional strain gauges, novel optical techniques such as stereo DIC proved to be able to capture the macroscopic Poisson coefficient with higher precision, thus reducing the margin of error. [ABSTRACT FROM AUTHOR]

This paper is focused on the mechanical performance of the Dou-Gong bracket at the corner under vertical load. A full-scaled specimen was tested under the static compressive load. The load-displacement curves, load distribution law and displacement of components were discussed. A finite element model was established and validated with test results. The deformation and stress of the whole Dou-Gong bracket and main components were analyzed, and the influence of the wood properties and friction coefficients was studied. The results show that there are four stages in the load-displacement curve and the plastic stiffness is 76.36% lower than that in the elastic stage. The components in the oblique 45° direction mainly transfer the force, while the load distribution ratios in the width and oblique 45° directions of the lower layer is closer to 1. The displacements of the components in oblique 45° direction in the No. 2 and No. 3 layers are smaller than those of the components in width direction. With the increase of the compressive strength, the elastic moduli in the radial direction and the friction coefficients, the stiffness in the plastic stage increases and the maximum displacement decreases. However, the compressive strength and the elastic moduli in the longitudinal direction have little effect on the load-displacement curves. [ABSTRACT FROM AUTHOR]

This paper presents a numerical approach for investigating fatigue delamination propagation in composite stiffened panels loaded in compression in the post-buckling field. These components are widely utilized in aerospace structures due to their lightweight and high-strength properties. However, fatigue-induced damage, particularly delamination at the skin–stringer interface, poses a significant challenge. The proposed numerical approach, called the "Min–Max Load Approach", allows for the calculation of the local stress ratio in a single finite element analysis. It represents the ratio between the minimum and maximum values of the stress along the delamination front, enabling accurate evaluation of the crack growth rate. The methodology is applied here in conjunction with the cohesive zone model technique to evaluate the post-buckling fatigue behavior of a composite single-stringer specimen with an initial delamination. Comparisons with experimental data validate the predictive capabilities of the proposed approach. [ABSTRACT FROM AUTHOR]

Fused Filament Fabrication (FFF) is one of the frequently used material extrusion (MEX) additive manufacturing processes due to its ability to manufacture functional components with complex geometry, but their properties depend on the process parameters. This paper focuses on studying the effects of process parameters, namely infill density (25%, 50%, 75%, and 100%), on the mechanical and thermal response of the samples made of poly(lactic acid) (PLA) reinforced with short glass fibers (GF) produced using FFF process. To perform a comprehensive analysis, tensile, flexural, compression, differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA) tests were used. The paper also aims to manufacture by FFF process of composite structures of the fuselage section type, as structural elements of an unmanned aerial vehicle (UAV), and their testing to compression loads. The results showed that the tensile, flexural and compression strength of the additive manufactured (AMed) samples increased with the increase of infill density and therefore, the samples with 100% infill density provides the highest mechanical characteristics. The AMed samples with 50% and 75% infill density exhibited a higher toughness than samples with 100% infill. DSC analyses revealed that the glass transition (Tg), and melting (Tm) temperature increases slightly as the infill density increases. Thermogravimetric analyses (TGA) show that PLA-GF filament loses its thermal stability at a temperature of about 311 °C and the increase in fill density leads to a slight increase in thermal stability and the complete degradation temperature of the AMed material. The compression tests of the fuselage sections manufactured by FFF made of PLA-GF composite showed that their stiffening with stringers oriented at an angle of ±45° ensures a higher compression strength than the stiffening with longitudinal stringers. [ABSTRACT FROM AUTHOR]

Mechanical behaviors at fatigue crack tips of cracked specimens under negative loading ratios are studied in detail by the finite element method in this paper. Three factors induced by specimen type and loading type on fatigue crack field are discussed, including constraint, compressive loading effect (CL effect) and crack contact closure. For mode I crack under negative loading ratios, the effects of the CL effect and crack contact closure on plastic strain accumulations are dominant, with the constraint effect being minor. The constraint effect has effects on the monotonous plastic zone, while the CL effect and contact closure both have effects on the reversed plastic zone (RPZ) and residual tensile plastic zone (RTPZ). That is, the higher the constraint, the smaller the size of the monotonous plastic zone; the greater the CL effect, or the smaller the contact degree, the larger the size of RPZ and RTPZ. For mode II crack, there is only CL effect on the crack tip field without the effect of constraint and contact closure, so plastic strain accumulation at the mode II crack tip is much greater than that at the mode I crack tip when they are under the same loading level. [ABSTRACT FROM AUTHOR]

This paper presents a proposed static test and numerical study on the mechanical properties of steel-shell–concrete-structure-immersed tunnel nodes, which is used to investigate the seismic performance and damage mechanism of steel-shell–concrete-structure-immersed tunnel nodes. The test is based on the immersed tube tunnel project in the deep China channel, and the nodes representing the outermost and innermost vertical walls of the immersed tube tunnel, i.e., L-shaped and T-shaped node specimens, were designed and fabricated at a scale of 1:5, and the specimens were mainly subjected to the combined effect of vertical axial compression and lateral displacement loads. The test results show that the L-shaped node will exhibit brittle damage characteristics with high lateral load carrying capacity and energy dissipation capacity during the ultimate load phase, while the T-shaped node exhibits bending damage with better ductility, so the outermost vertical wall should be locally reinforced to ensure the necessary ductility of the structure in the actual project. In addition, by comparing the numerical calculation and experimental results, it is found that there is good agreement in terms of load–displacement curves and crack distribution, which shows that the modeling method proposed in this paper can accurately simulate the mechanical properties of immersed tunnel nodes and can guide the section design of immersed tunnels with steel shell–concrete structures. [ABSTRACT FROM AUTHOR]

This paper evaluates the various approaches to strength and stiffness analysis of fracture osteosynthesis using a headless Herbert screw. The problem has been extensively addressed using several scientific approaches, namely the analytical approach, stochastic approach, experimental approach, and (marginally) using the finite elements method. The problem is illustrated on the use of a prototype headless screw Ti: 4.0/1.4 × 30/7 (manufacturer: Medin, Czech Republic) and the surgical treatment of the fifth metatarsal fracture. Mathematical equations for the analytical calculation of the maximum stresses in the screw were established for tensile/compression loading. This problem is also interesting because of its static indetermination in tension and compression; for this reason, it was necessary to use the deformation condition, i.e., the relationship between screw extension and bone contraction. The stochastic (probabilistic) approach, i.e., application of the Monte Carlo method, takes advantage of the mathematical equations derived during the analytical solution by respecting of the natural variabilities and uncertainties. The analytical and stochastic approaches were validated by measurements on porcine bones and by the finite element method. The data measured experimentally were also processed and used for deriving an equation, appropriately approximating the data. The main part of the measurement was to determine the axial force generated during osteosynthesis with a headless screw. The obtained compressional force was used to determine the maximal stress in the screw and bone. Finally, the methods were compared. In this paper, comprehensive and original approaches based on the authors' experience with multiple methods are presented. Obtained results are necessary for headless screw designers during optimalization of the implants and are also useful for surgeons developing new surgical techniques. This biomechanical problem was solved in cooperation with the engineering industry and physicians to improve the quality of care for patients with trauma in orthopedics and surgery. [ABSTRACT FROM AUTHOR]

A method for the determination of mechanical properties under compressive load is presented in this study. The short-span compression test is standardized for paper-based materials and was adapted for veneer in this study. Rotary cut veneer and solid wood of European beech (Fagus sylvatica L.) was tested parallel and transversal to fiber direction. The veneer thickness was varied between 1 and 3 mm. The mechanical properties Young's modulus, Poisson's ratio, yield point and compressive strength were measured. The results show that the correct determination of Poisson's ratio depends on the veneer thickness as well as on the fiber direction. For veneer with a thickness of at least 3 mm, it is suitable in fiber direction, but not transversal to the fiber direction. The comparison of the mechanical properties between veneer and solid wood confirms that the lathe checks mainly influence the veneer properties transversal to the fiber direction. [ABSTRACT FROM AUTHOR]

This paper focuses on the finite element analysis simulation of the impact properties of composite sandwich structures made of carbon fiber-reinforced polymer lamina. In the existing studies, the composite sandwich structures with A-shaped cores have superior mechanical properties under quasi-static plane compression loads compared to W-shaped, Y-shaped, and X-shaped cores. However, there is limited research on the impact resistance of this structure. This paper studied the resistance of a composite A-shaped core structure to ballistic impact. Using ABAQUS/explicit finite element analysis software, ballistic impact tests for the composite A-shaped core structure were simulated based on the Hashin and Yeh failure criteria with a progressive damage model introduced in the user-defined subroutine VUMAT. First, the composite Y-shaped core sandwich structure was verified via experiments and simulations to determine the accuracy of the method, and then the composite A-shaped sandwich structure was subjected to a series of ballistic impact simulations. With varied impact velocity, the damage to the front and rear face sheet and cores via ballistic loads was simulated to illustrate the overall dynamic response process of the sandwich structure. Subsequently, a curve was fitted using a ballistic limit velocity equation, which was used as the criterion to evaluate the impact resistance of the composite A-shaped core structure. The results showed that, under the same relative density and the same number of component layers, the ballistic limit velocity of the composite A-shaped core sandwich structure was bigger than the composite Y-shaped core sandwich structure. The composite A-shaped core structure had 12.23% higher ballistic limit velocity than the composite Y-shaped core, indicating the impact resistance capabilities of the A-shaped core structure. In addition, the impact location's effect on the impact response was investigated. [ABSTRACT FROM AUTHOR]

Few works investigate the fatigue of short fiber reinforced thermoplastics under cyclic compression. Furthermore, the heat buildup approach to quickly predict the fatigue lifetime of these materials has not yet been investigated for compression–compression loadings. This paper first describes an experimental protocol to perform well‐controlled cyclic compression tests without anti‐buckling device that may induced bias. The uniaxiality of the global loading is checked during the test based on kinematic and thermoelastic coupling field measurements. Then, the paper compares the results from fatigue and heat buildup tests performed on polyetheretherketone reinforced with 30 wt% of short carbon fibers for several load ratios. It is shown that the fatigue lifetime is higher in compression than in tension and depends on the compression load ratio. The heat buildup approach appears to be relevant to quickly predict the fatigue lifetime of the material for the different loading ratios studied, including compression–compression. Highlights: Protocol to perform well‐controlled compression tests based on field measurements.Influence of load ratios on fatigue lifetime of PEEK CF30 under compression loadings.Quick prediction of fatigue lifetime from heat buildup measurements in compression. [ABSTRACT FROM AUTHOR]

The electrical contact resistance between the Gas Diffusion Layer (GDL) and the BiPolar Plate (BPP) used in Polymer Electrolyte Membrane Fuel cells (PEMFCs) is responsible for a substantial amount of Ohmic losses in the electrical power generator. This contact resistance was measured for a variety of carbon paper GDLs under cyclic mechanical compression between 0 and 8 MPa according to the Transmission Line Method (TLM). Contact resistance and strain hysteresis were noticed as a result of cyclic compression. The effect of GDL structure and composition on the electrical contact resistance and its cyclic behaviour has been evaluated. The contact resistance was found to decrease non-linearly with compression; more than 75% of reduction was attained at 2.5 MPa. The electrical contact resistance's difference between the different cycles of compression decreased with compression loads. Graphitised straight fibre Toray GDLs demonstrated the smallest contact resistance followed by the MicroPorous Layer (MPL) and the felt fibre substrate. The SGL straight fibre substrates exhibited the highest contact resistance. The felt fibre structure exhibited the smallest difference rates between the cycles of compression. • GDL - BPP electrical contact resistance is measured under cyclic compression. • A non-linear decrease of the contact resistance is observed with compression. • Contact resistance difference between cycles decreases with higher compression loads. • Graphitised carbon paper GDLs exhibit the smallest contact resistance. • The felt structure GDL is the least sensitive to cyclic compression. [ABSTRACT FROM AUTHOR]

In Recognition of the 90th Birthday of Millard Beatty Professor Beatty has contributed a wide variety of research papers and book articles on topics in finite elasticity, continuum mechanics and classical mechanics, including some fundamental experimental work. Finally, Professor Beatty's passion for teaching is exhibited in a number of his didactic related articles on classical mechanics and is emphasized further in two volumes on the principles of engineering mechanics. In a series of fundamental papers, the first of which, Part 1, appeared in 1992 in this journal, Beatty, together with Michael Hayes, developed the constitutive theory of an isotropic Bell constrained material. While this three-part work concluded their joint research on Bell materials, later, in 2005, Beatty and Hayes got together again and arranged for the production, and served as co-editors of, the special volume: "Mechanics and Mathematics of Crystals - Selected Papers of J. L. Ericksen". Along the way, Beatty also developed a number of special mathematical results which dealt with: determinants having complex conjugate elements; general integrals arising in plane finite elasticity; and an integral identity applicable to continuum mechanics. [Extracted from the article]

One of the important directions for green development in the world today is to expand the application methods of recycled concrete, improve the utilization rate of waste aggregates, and slow down the consumption of natural resources. The column structure with a large length and slenderness ratio is the most widely used compression unit in practical engineering, which conforms to the principle of sustainable development. In this paper, we study the mechanical properties and failure modes of long columns fabricated from steel tubes filled with recycled large aggregate self-compacting concrete (RLASCC-ST-LC) under compression load. Moreover, we examine the influence of steel tube thickness, recycled large-aggregate particle size, the strength of self-compacting concrete, and the length-to-diameter ratio on the performance of the members through finite element modelling. The results indicated that RLASCC-ST-LCs exhibited different degrees of buckling damage, and the damage processes were basically the same as that of steel tube concrete. When the thickness of steel pipe increased from 4 mm to 5 mm, the ultimate bearing capacity of the component increased by 12.1%; when the strength of self-compacting concrete increased from 30 MPa to 40 MPa and 50 MPa, the ultimate loads of the component increased by 6.96% and 12.4%, respectively. However, the increase in the aspect ratio weakened the bearing capacity of the component, and the ultimate bearing capacities reduced by 4.78% and 10.51% when the aspect ratios were 8, 10, and 12. Finally, based on the existing design codes, the theoretical calculation formulas are proposed for the ultimate bearing capacities of RLASCC-ST-LCs. These findings have significant implications for the widespread application of RLASCC-ST-LCs. [ABSTRACT FROM AUTHOR]

The new-type stainless steel–concrete–carbon steel double-skin tubular (SCCDST) members, characterized by their exceptional corrosion resistance and mechanical bearing capacity, have promising applications in ocean engineering, particularly in deep-water engineering. The external hydraulic pressure and interfacial action of various materials intensify the complexity of composite performance of SCCDST members. This paper describes an analytical investigation on the concentric compressive performance of SCCDST members under external hydraulic pressure. The full-range mechanism, including load–displacement response, bearing capacity contribution, and contact pressures, was investigated through the finite element (FE) model that was validated by the failure mode, bearing capacity, and response of axial load versus strain. Subsequently, influences of key geometric–physical parameters were analyzed, e.g., diameter-to-thickness ratios (Do/to, Di/ti), material strengths (fyo, fyi, and fc), hollow ratios (χ), and water depths (H). Typical results indicate that: the initial active confinement action derived from the hydraulic pressure can enhance the interfacial contact pressure and axial compression capacity of SCCDST members due to the tri-axial compression state; the enhancement of confinement effect is mainly from the interfacial interaction between outer stainless steel tube and concrete infill; influence of water depth on bearing capacity cannot be ignored, e.g., the bearing capacity of an SCCDST member with larger hollow ratio (χ = 0.849) is not enhanced under a higher hydraulic pressure (H = 900 m) because of the cross-sectional buckling failure risk. Finally, a modified method considering the effect of water depth was proposed and verified for SCCDST members under hydraulic pressure. [ABSTRACT FROM AUTHOR]

The woven structure made of naturally curved (in-plane) ribbons has smooth geometry and fewer geometric imperfections, but there is no study of its buckling mechanical properties under vertical loads. The aim of this paper is to investigate buckling mechanical properties of spherical woven structures. Three spherical woven structures with different ribbon types and six new spherical woven structures with different ribbon widths and thicknesses were designed and the quasi-static vertical compression tests were carried out. The buckling load of spherical woven structures were studied by nonlinear finite element and ring buckling theory. Results indicate that the failure mode of the spherical weave structure under vertical loading can be divided into two stages, where a flat contact region forms between the spherical weave structure and the rigid plate and inward dimple of ribbons. Spherical weave structures using naturally curved (in-plane) ribbon weaving have better buckling stability than those woven with straight ribbon. Based on theoretical and finite element analysis, we propose a buckling load equation and buckling correction factor equation for the new spherical weave structure under vertical compression load. The formula is validated and has good agreement with the test results, which could help to design the stability of spherical weave structures with in-plane ribbons. [ABSTRACT FROM AUTHOR]

This paper presents the results of experimental and numerical investigations aimed at enhancing the flexural capacity of Precast Concrete Corbel Beam–Column Connections (PC-CBCCs) using Fiber-Reinforced Plastic (FRP) sheets. The experimental study primarily focused on assessing the flexural capacity of pinned PC-CBCCs reinforced with FRP layers, comparing them to a moment-resisting connection. A series of half-scale specimens, including three PC-CBCCs with varying FRP configurations, were tested alongside one in situ concrete fixed connection. The first specimen (PC-1) utilized L-shaped and full-wrap FRPs, whereas PC-2 and PC-3 employed both U-shaped and full-wrap layers. The objective is to quantify the ultimate flexural capacity of PC-CBCCs reinforced by FRP sheets. In PC-3, the external anchorage is introduced to assess its influence on delaying the FRP layer debonding under lateral loading. The effects of the FRP layer thickness, locations, and potential debonding are examined under unidirectional static tests while applying a constant axial compressive load to the columns and subjecting the beams to lateral loads until fracture. The test results illustrate that strengthening the corbel connection with L-shaped FRP or spiral U-shaped FRP sheets without mechanical anchorage cannot result in a significant bending capacity due to debonding. However, with the incorporation of mechanical anchors, the connection manages to enhance the moment capacity to 81% of a fixed connection's flexural capacity. Additionally, a finite element model of the PC-CBCCs and a fixed joint is developed to simulate nonlinear static analyses of the connections using ANSYS 19.2 software. The simulation model is precise in predicting the initial stiffness and ultimate capacity of the beam–column joints, as verified by the experimental results. A comprehensive comparison is conducted to determine their responses by employing various FRP configurations and properties. Moreover, design parameters such as bond length and thickness of the FRP sheets, along with appropriate mechanical anchorage, are identified as effective in preventing debonding, and delamination. However, wrapping the beam far away from the joint interface has a minimal impact on the failure mode, stress reduction, and load-bearing capacity. [ABSTRACT FROM AUTHOR]

It is known that ceramic–polymer composite materials can be used to manufacture spherical bodies in the category of balls. Since balls are frequently subjected to compression loads, the paper presents some research results on the compression behavior of balls made of ceramic composite materials with a polymer matrix. The mathematical model of the pressure variation inside the balls highlights the existence of maximum values in the areas of contact with other parts. Experimental research was carried out on balls with a diameter of 20 mm, manufactured by 3D printing from four ceramic–polymer composite materials with a polymer matrix: pottery clay, terracotta, concrete, and granite. The same ceramic–polymer composite material was used, but different dyes were added to it. A gravimetric analysis revealed similar behavior of the four materials upon controlled heating. Through the mathematical processing of the experimental results obtained by compression tests, empirical mathematical models of the power-type function type were determined. These models highlight the influence exerted by different factors on the force at which the initiation of cracks in the ball materials occurs. The decisive influence of the infill factor on the size of the force at which the cracking of the balls begins was found. [ABSTRACT FROM AUTHOR]

Although there are currently many types of lattice shell joints with different characteristics, assessing the flexural capacity of lattice shell joints is always a great challenge. In this paper, a fan-shaped assembled joint and a welded joint for comparison were subjected to bending tests to investigate the flexural behavior and rotational stiffness of the assembled joint. The strain distribution, load–displacement curve, moment–rotation curve, and damage modes of key parts were analyzed to determine the vulnerable parts of the joints. Our test results show that, with an initial rotational stiffness of about one third of that of the welded joint, the assembled joint specimen exhibits the obvious characteristics of a semi-rigid joint. The finite element analysis results were in good agreement with the experimental results. The results of our parametric analysis show that the rotational stiffness and ultimate moment of the assembled joint increase with increases in the spacing of the bolts and the number of bolts. The performance of the high-strength bolts had a significant influence on the flexural stiffness of the assembled joints. The spacing of the bolts and the number of bolts for the assembled joint are suggested to be greater than the height of the member section and more than three, respectively. The proposed theoretical formula can approximately simulate the initial rotational stiffness of the joint. More in-depth investigations are required in the future for assessing the mechanical behavior of FSA joints subjected to combined bending–compression loads. [ABSTRACT FROM AUTHOR]

Post-filling coarse aggregate concrete (PFCC) is a new type of concrete that achieves energy-saving and emission-reduction goals through optimizing material proportions. The post-filled coarse aggregates can save the amount of cement material used, improve the strength and elastic modulus, prolong the service life of the material, and reduce expenses. We conducted a biaxial tension–compression test on PFCC cubic specimens, analyzed the strength and stress–strain curve regularity under different post-filling ratios (PFRs) and stress ratios, and proposed a new failure criterion suitable for PFCC. The results demonstrated that the tensile strength and compressive strength of each post-filling ratio concrete specimen under biaxial tension–compression action are lower than its uniaxial tensile and uniaxial compressive strength under the same post-filling ratio. Under the same stress ratio, the variation pattern of the post-filling ratio was the same as that under uniaxial stress, with the maximum value occurring at a PFR of 20%. The strength change rule was affected by both the stress ratio and the post-filling ratio. From the stress–strain curve, it can be seen that the presence of tensile stress significantly reduces the stiffness and ductility of PFCC under biaxial tensile and compressive loading. The strain corresponding to the peak strength of the σ3/fc-ε3 curve was much smaller than the peak strain under uniaxial compression. For example, at a stress ratio of (0.05:1), the strain ε3 in the compression direction was on average about 50% to 60% of the uniaxial compression strain under the same PFR. The stress–strain curve of PFCC under biaxial tensile and compressive loading was approximately linear throughout the loading process. A failure criterion for PFCC under biaxial tension–compression loading was established, and the calculated values agreed well with the test values. This paper provides references and research data for the study of PFCC under complex stress conditions. [ABSTRACT FROM AUTHOR]

Thin-walled galvanized helical corrugated steel tubes (HCSTs) filled with concrete are promising composite members, consisting of concrete, an anti-corrosion shell, and a multifunctional exterior corrugated steel tube. To investigate the synergistic working mechanism of concrete-filled HCSTs (CFHCSTs), six specimens were designed for axial compression tests, with the inner diameter of the column and the volumetric steel ratios of the longitudinal reinforcement as the variation parameters. The results show that HCSTs can better confine the concrete core and increase its strength. The failure mode of HCSTs is significantly influenced by the column's diameter, and those with a smaller diameter are prone to slide failure and lock seam tearing. The strains and stresses on HCSTs are discussed in detail to elucidate the confinement effect. This paper proposes a suitable design method to predict the ultimate axial compression load capacity of CFHCST columns based on early studies on steel tube-confined concrete. [ABSTRACT FROM AUTHOR]

This paper presents size dependent stability analysis a cantilever micro laminated beam embedded in elastic medium by using the modified coupled stress theory which includes the length scale parameter. The micro beam subjected to compressive load is considered as three composite laminas and embedded in elastic medium which is modelled in the Winkler foundation model. In the obtaining of the governing equations, the energy principle is used. In the solution of the buckling problem, the energy based Ritz method is implemented with algebraic polynomials. In order to accuracy obtained expressions and used method, a comparative study is performed. Many parametric studies are presented in order to investigate the buckling of laminated micro beams. For this purpose, effects of stacking sequence of laminas, geometric parameters, length scale parameter, fiber orientation angle, the parameter of elastic medium on critical buckling loads of laminated micro beams are investigated. [ABSTRACT FROM AUTHOR]

This paper focuses on the study of the strength of facade sandwich panels used in building construction. The paper describes the results of experimental and numerical research on the behavior of sandwich panels made of polyisocyanurate core (PIR) and their structural connections when exposed to tensile and compressive loads. In the initial phase of this study, laboratory tests were performed to determine the physical and mechanical characteristics of the material from which the sandwich panels are made. Laboratory tensile and compression tests were performed on small samples of sandwich facade panels. In order to verify the obtained results, they were compared with the numerical analysis performed in the ANSYS software. The numerical model was found to accurately predict the results of the laboratory tests, suggesting that the model can be used to predict the behavior of these panels under different loads in service. The study showed that the foam core sandwich panel exhibits excellent mechanical properties. The results indicate the suitability of foam-based composite structures in the construction industry for various applications, such as roof and wall structures. The findings of this study may help in the development of lightweight and durable construction materials for the industry. [ABSTRACT FROM AUTHOR]

Compression of paperboard is a common procedure during industrial package forming and better knowledge of the material response is needed to avoid defective packages and waste. To go beyond current modelling approaches, experimental identification of mechanisms underlying the macroscopic stress–strain responses is needed. In this study, in-situ uniaxial compression of paperboard is studied through synchrotron tomography at high spatiotemporal resolutions. Both the microstructural evolution of the fibre network and the actual boundary conditions of the loading were quantified and analysed. At the microscale, the loading equipment plates were not perfectly flat resulting in an increasing sample-equipment contact area with loading. This is, however, shown to only have a small effect on the form of the macroscopic stress–strain curves. The evolution of 3D strain fields showed that strain accumulated close to the sample surfaces in the early part of the compression process, whereafter the main deformation zone shifted to the out-of-plane centre. Both fibre walls and pore volumes were observed to decrease during loading (and recover partly after unloading). Regarding the pore volume, the main reduction mechanism was seen to be closure of layers between fibres. Even if the total pore volume reduction was seen to be the dominant deformation mechanism in a second stage of compression, the volumetric change of fibre walls was non-negligible. Fibre wall compression is not commonly considered in theoretical treatments of paperboard compression, but this work suggests that the stored elastic energy could be a driver for the elastic recovery of the fibre network during unloading. [ABSTRACT FROM AUTHOR]

This paper introduces a novel type of buckling restrained braces (BRBs) called core-separated assembled BRBs (CSA-BRBs). These braces are comprised of two single BRBs that are confined by lightweight concrete-infilled tubes, which are longitudinally connected by two continuous webs. The CSA-BRBs utilize materials more efficiently by increasing the height of the webs to create a large inner cavity, leading to an economical design. This paper predicts the threshold of the restraint ratio of CSA-BRBs approximately. This is achieved by assuming that the maximum moment resulting from applied loads at mid-height is less than the moment-bearing resistance that is conducted according to the outermost fiber of the external restraining section reading yielding. Elastic-plastic numerical analysis is conducted using FEM with beam elements for CSA-BRBs that are subjected to both monotonic and cyclic axial loads. The load resistance, hysteretic performance, and failure mechanism of CSA-BRBs are investigated by varying their restraining ratios. It is recommended that the restraint ratio threshold of CSA-BRBs under monotonic axial compression is used as a bearing type and the restraint ratio threshold of CSA-BRBs under axially compressive-tensile cyclic loads as an energy-dissipation type. This method provides a complete design for CSA-BRBs. [ABSTRACT FROM AUTHOR]

Nominated for Eurosteel 2021 Best Paper Award The paper addresses the instability of large angle columns in high‐strength steel subjected to compression loads. It presents a number of compression tests on such columns with different eccentricities and slenderness and the resulting different buckling failure modes observed. The experimental campaign is intended to widen our understanding of the behaviour of high‐strength steel columns with large angle sections in compression and bending and so to complement previous experimental studies. The tests were accompanied by numerical analyses and calculations of the load carrying capacities based on current Eurocode 3 design recommendations. The numerical simulations were conducted using the FEM software FINELG, which takes into account the influence of geometrical and material non‐linearities. The numerical and analytical results are compared with the corresponding experimental ones. The experimental campaign and the numerical simulations were conducted as part of the ANGELHY project funded by the European Commission's Research Fund for Coal and Steel (RFCS). [ABSTRACT FROM AUTHOR]

As part of the ongoing revision of the Eurocodes, design provisions in EN 1999‐1‐1 on the buckling of longitudinally welded aluminium compression members have been subjected to a critical review. The numerical investigations described in part 1 of the paper were conducted because a need for improvement was identified. In part 2 of the paper, the main observations are presented in qualitative terms. Those observations are: the influence of the allocation of the materials to buckling classes, the influence of the imperfections plus the cross‐section geometry including the position and size of the HAZ within the cross‐section. Part 3 will conclude this paper by discussing the proposed design approaches in detail. [ABSTRACT FROM AUTHOR]

Buckling analysis of functionally graded porous nano conical shell subjected to axial compression is studied in this paper. The porous material properties vary across the thickness by a special function. First order shear deformation theory and modified couple stress theory are used to obtain the governing equation. Shells' nonlinear equilibrium and linear stability equations are obtained by Euler's relations and Treftz principles. To solve the stability equations, the differential quadrature method (DQM) is used. The accuracy and the reliability of this paper are compared with reported studies. Finally, the effect of shell's porous parameters, boundary condition, vertex angle and length scale on the amount of critical buckling force is discussed. [ABSTRACT FROM AUTHOR]

Natural porous materials adjust their resulting mechanical properties by the optimal use of matter and space. When these are produced synthetically, they are known as mechanical metamaterials. This paper adds degrees of tailoring of mechanical properties by producing double levels of gradation in lattice structures via cross-section variation in struts in uniformly periodic lattice structures (UPLS) and layered lattice structures (LLS). These were then additively manufactured via material extrusion (ME) and vat photopolymerization (VP). Their effective mechanical properties under compressive loads were characterized, and their stiffness contrasted with finite element models (FEM). According to the simulation and experimental results, a better correlation was obtained in the structures manufactured via VP than by ME, denoting that printing defects affect the correlation results. The brittle natural behavior of the resin caused a lack of a plateau region in the stress–strain curves for the UPLS structures, as opposed to those fabricated with ME. The LLS increased energy absorption up to 244 % and increased the plateau stress up to 100 % compared to the UPLS. The results presented in this paper demonstrate that the mechanical properties of lattice structures with the same base topology could be modified by incorporating variations in the strut diameter and then arranging these differently. [ABSTRACT FROM AUTHOR]

In this paper, precast lightweight Concrete Sandwich Panels (CSP) with reinforced concrete skins/wythes, truss shear connectors and expanded polystyrene core are proposed to be a good alternative for replacing conventional load bearing brick masonry walls. Literature review indicated that studies examining the failure modes of concrete sandwich panels under axial compression are not reported. Towards filling this gap and for developing design guidelines for practical applications, in this paper, failure modes of CSP are theoretically defined. Experimental investigations are conducted to determine the actual failure modes, strength and behaviour of the panels under axial compression. The failure modes observed from the experimental study are compared with the theoretical failure modes. Test results indicated that CSP can be used for practical applications as an alternative to conventional brick masonry walls. Attempts are also made to find the applicability of available strength predicting formulas of sandwich members/RC walls for concrete sandwich panels. Results showed that the available formulas have to be modified for predicting the axial compressive strength of CSP with reasonable accuracy. [ABSTRACT FROM AUTHOR]

The present study investigates torsional and compressive loading of a paperboard package. Finite element (FE) analyses simulating the tests were performed to improve understanding of the stresses and deformations in the paperboard during loading. A simple experimental characterization of the necessary material properties could be performed to represent the multi‐ply paperboard as a single‐ply structure. The results from the single‐ply model were compared with a laminate model, and the differences between the models were small. Comparing experimental and FE simulations of box compression and torsion showed that the FE models could accurately predict the response curves. However, in the simulations, there was an overprediction of the maximum compressive force and maximum torque, which was expected since geometrical imperfections and the heterogeneous internal structure of the material were not accounted for in the material model or the FE model. Local yield lines formed at the onset of non‐linearities in the package load–displacement curves. Therefore, the strength of the paperboard affects the maximum compressive strength and maximum torque, and the bending stiffness of the paperboard only had a minor effect. When a first local maximum was reached, the number of FE that reached the failure stress increased exponentially. The simulations also showed that box compression was not an effect of package height, but higher packages had a lower maximum torque. [ABSTRACT FROM AUTHOR]

In the present paper, thermo‐mechanical stability analysis of geometrically imperfect porous functionally graded plates (FGP) with geometric nonlinearity is presented. The equilibrium, stability, and compatibility equations are derived using Logarithmic structural kinematics in conjunction with the von‐Karman type of geometric nonlinearity. A logarithmic‐based shear‐strain function has been used for the first time for the buckling response of functionally graded material (FGM) plates. Generic imperfection function has been implemented to incorporate the various imperfection modes like sin‐type or global type in the formulation. The effective materials properties of the plates with porosity inclusion have been computed using modified power law. The plate is subjected to uniaxial and biaxial compression as well as combined compression and tension along with thermal loading. An exact expression for the critical buckling load and critical buckling thermal load of geometrically imperfect porous FGM plate for each loading case has been developed. After confirming the excellent accuracy of the current exact solutions, the effect of geometric imperfection, porosity inclusion, and geometric configurations on the nonlinear stability of the FGM plate have been discussed extensively. The results presented in this paper will be used as a benchmark for future research. [ABSTRACT FROM AUTHOR]

Based on fracture mechanics theory, a finite element method was used to determine the stress intensity factors of the inclined crack on the inner surface of the pipe under axial compression load and external pressure. The effects of different influencing factors on the stress intensity factor along the crack front considering crack closure were systematically explored, which were different to those under internal pressure. The effects of high aspect ratio on KII, the crack inclination asymmetry caused by curvature and the effects of the friction coefficient on the stress intensity factors of the pipe with an inclined inner surface crack under axial compression load and external pressure were explored in this paper. To be fit for defect assessment, the solutions for stress intensity factors KII and KIII were derived, and new correction factors fθ and fμ were proposed in the empirical solutions to accommodate the crack inclination asymmetry and the friction coefficient, respectively. [ABSTRACT FROM AUTHOR]