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AbstractIn this paper, a static and free vibration analysis of functionally graded porous shallow shells with double curvature containing an even distribution of porosity is investigated using a trigonometric shear and normal deformation theory. Both the effects of transverse shear and normal strains are included in the present theory to investigate their effects on the responses of FGM porous shells. The theory satisfies zero transverse shear stress conditions at the top and bottom surfaces of the shell. Hamilton’s principle is used for obtaining governing equations and boundary conditions of the present theory for functionally graded porous shallow shells. The FGM porous shell is assumed isotropic at any point within the shell domain, with its elastic properties varying across its thickness by a power law in terms of the volume fractions of the shell constituents. The simply-supported FG porous shell is analyzed in the present study using the Navier method. The numerical results of FGM porous plates are obtained and compared with other higher-order theories available in the literature to verify the present theory. Further, the numerical results are presented for the FGM porous shells with double curvature. The effects of a/h ratios, porosity distribution factor, and radii of curvature on deflections, stresses, and fundamental frequencies are presented. The solution of hyperbolic and elliptical FGM porous shells is presented for the first time in this paper. [ABSTRACT FROM AUTHOR]

According to the requirement of "structural design and manufacturing feasibility" of the electric vehicle battery pack, the design of carbon fiber composite material instead of metal material is studied in this paper. Firstly, the cross-section performance of the composite battery pack was determined by the principle of equal stiffness. Moreover, the different layups were verified from a manufacturing point of view and the advantages and disadvantages of the three improvements, linear shear, V-shear, and V-shear + linear shear, were compared. Secondly, the three steps of free size optimization, size optimization, and layup sequence optimization were carried out for the lower box to find the lightest structure; the upper box was directly reinforced with a "King" type to alleviate the excessive amplitude. The total mass of the final pack is 14.09 kg, with a weight reduction rate of 56%. Finally, the volume-of-fluid (VOF) method in ANSYS Fluent is chosen to simulate the curing process. The molding results of four injection methods are discussed, while resin viscosity and pressure are considered to find the optimal process parameters. The work in this paper provides a reference for the lightweight application of composite materials in new energy vehicles. [ABSTRACT FROM AUTHOR]

AbstractShaped charges are extensively utilized in various rock engineering fields for directional fracturing. Numerous scholars have conducted extensive research on this topic, yielding significant results and widespread application in engineering projects. Efforts have focused on improving the directional fracture effects and fully utilizing the energy generated by the explosion to enhance the directional blasting effects of shaped charges and minimize damage to the rock mass in areas not targeted by the shaped energy. This approach aims to preserve the integrity and stability of the rock mass in the areas unaffected by the directional fracture, thereby reducing damage to the surrounding rock. This study builds on the foundations of explosion mechanics. It incorporates a novel digital laser dynamic caustic line experiment system and pressure fields, and numerical analysis techniques. The research systematically analyzes the process of explosive action in shaped charges and proposes a new type of dual polymer charge. This novel charge is compared to traditional and common charges. The findings revealed that, compared to standard-shaped charges, the new dual-shaped charge achieves a more effective directional fracturing, The rock damage is less in the direction of non-gathering energy. Under the conditions of the same amount of explosive and the same decoupling coefficient, The crack propagation length of common charge is 1.34 times of the diameter of the gun hole, the crack propagation length of shaped charge is 10.17 times of the hole diameter, The crack propagation length of the new dual-charge is 19.67 times of the hole diameter.HIGHLIGHTSIn this paper, a new type of dual-charge is proposed. The findings revealed that, compared to standard-shaped charges, the new dual-shaped charge achieves a more effective directional fracturing, The rock damage is less in the direction of non-gathering energy. Under the conditions of the same amount of explosive and the same decoupling coefficient, The crack propagation length of common charge is 1.34 times of the diameter of the gun hole, the crack propagation length of shaped charge is 10.17 times of the hole diameter, The crack propagation length of the new dual-charge is 19.67 times of the hole diameter.1.Following the charge explosion, influenced by the shaped charge tube, the detonation wave and explosive gas alter, expanding outward in an approximate "elliptical" shape. The explosion stress field distribution is approximately "one"-shaped in the direction of energy concentration. The primary explosive crack expands along the direction of energy accumulation, while the secondary cracks predominantly distribute in the perpendicular direction. The seam width and the transmission coefficient (material) influence the condenser’s concentration effect.2.Compared to ordinary charge blasting, shaped charge blasting exerts a pronounced guiding effect on the explosion stress field. The stress field primarily transfers along the direction of energy concentration, with the stress being markedly greater in this direction than in the direction of non-concentrated energy. In comparison, dual charge blasting undergoes two convergence effects, with longer durations and distances of convergent action. The stress field generated by dual-charge blasting is significantly greater than that of the shaped and common charges, offering enhanced effects.3.Agglomeration length is a crucial factor in the agglomeration effect. Explosion energy directly transfers to the solid medium via the coalseam, minimizing explosion energy loss in the air medium and controlling the detonation wave shape and explosive gas flow in the energy accumulation direction, resembling "one." The dipolymer charge notably extends crack propagation length in the polymer direction and mitigates damage in the non-polymer direction.In this paper, a new type of dual-charge is proposed. The findings revealed that, compared to standard-shaped charges, the new dual-shaped charge achieves a more effective directional fracturing, The rock damage is less in the direction of non-gathering energy. Under the conditions of the same amount of explosive and the same decoupling coefficient, The crack propagation length of common charge is 1.34 times of the diameter of the gun hole, the crack propagation length of shaped charge is 10.17 times of the hole diameter, The crack propagation length of the new dual-charge is 19.67 times of the hole diameter.1.Following the charge explosion, influenced by the shaped charge tube, the detonation wave and explosive gas alter, expanding outward in an approximate "elliptical" shape. The explosion stress field distribution is approximately "one"-shaped in the direction of energy concentration. The primary explosive crack expands along the direction of energy accumulation, while the secondary cracks predominantly distribute in the perpendicular direction. The seam width and the transmission coefficient (material) influence the condenser’s concentration effect.2.Compared to ordinary charge blasting, shaped charge blasting exerts a pronounced guiding effect on the explosion stress field. The stress field primarily transfers along the direction of energy concentration, with the stress being markedly greater in this direction than in the direction of non-concentrated energy. In comparison, dual charge blasting undergoes two convergence effects, with longer durations and distances of convergent action. The stress field generated by dual-charge blasting is significantly greater than that of the shaped and common charges, offering enhanced effects.3.Agglomeration length is a crucial factor in the agglomeration effect. Explosion energy directly transfers to the solid medium via the coalseam, minimizing explosion energy loss in the air medium and controlling the detonation wave shape and explosive gas flow in the energy accumulation direction, resembling "one." The dipolymer charge notably extends crack propagation length in the polymer direction and mitigates damage in the non-polymer direction. [ABSTRACT FROM AUTHOR]

AbstractThe paper explores the increasing concern over environmental vibrations resulting from machine operation and rail transit. Notably, low-frequency vibrations generate surface waves with characteristics like significant energy carrying capacity, long-distance propagation, and slow attenuation. The primary challenge in ground vibration attenuation lies in addressing low-frequency vibrations. The study employs the finite element method to investigate the vibration attenuation of a three-component local resonance pile in three-dimensional space. The analysis delves into the impact of the unit cell structure’s geometry size on bandgaps, and the influences of the period number on the Attenuation Zones (AZs) are also discussed. Furthermore, a comparison is made regarding the vibration attenuation performance of a two-component local resonance pile. The findings reveal that the appropriate design of a three-component local resonance pile can generate low-frequency complete bandgap. The concrete radius, rubber layer thickness, and buried depth of the pile significantly affect Rayleigh wave bandgap. Frequency domain analysis indicates that an increase in period number expands AZs into the bandgap range. Time domain analysis demonstrates a noticeable decrease in ground acceleration amplitude within the bandgap range. The research results presented in this paper offer a novel approach to address the low-frequency vibration attenuation. [ABSTRACT FROM AUTHOR]

AbstractWe develop a new model called C-311 for laminated composite beams based on a new zig-zag theory that is firstly proposed in this paper. The in-plane displacement field of the model includes two parts: part one is regarded as the global displacement field which is made of third-order polynomial about z, part two is the local displacement field which is the new zig-zag theory. By satisfying inter-laminar transverse stress continuity and the free surface conditions, the local displacement unknown variables can be eliminated, and the final displacement field should be expressed by the fixed number of unknown displacement variables. For testing the ability of C-311, the classical example about a simply supported laminated beam is investigated under mechanical loading in this paper. In comparison with other models of laminated composite beams, the numerical results show that the present model can give more accurate analysis, and are closer to the exact solutions. Especially the accurate transverse shear stresses are able to be directly obtained from the constitutive equations without any processing, and that is never done for other zig-zag models existing in the literature and benefit for practical engineering applications in the finite element method. [ABSTRACT FROM AUTHOR]

Despite the complex punching shear behavior of reinforced concrete slabs have been comprehensively addressed in the literature, it is further essential to develop a universal design model comprising high accuracy and the simplicity for design practicability, adaptable to diverse conditions encountered in practice. Artificial intelligence applications, artificial neural networks (ANN), and more recently, various machine learning (ML) and deep learning (DL) techniques veer off in a new direction in structural engineering context with improved accuracy and efficiency. The paper begins with the assessment of the capabilities of various artificial intelligence applications in predicting the punching shear strength of slab-column connections without shear reinforcement through the extensive database using 650 punching shear experiments from the literature. Critical parameters influencing the punching shear strength as well as the precision of the current code provisions in predicting this feature were then thoroughly examined in the paper. The results shown in this paper validated the competency of artificial intelligence applications in predicting the punching shear strength of such connections with increased accuracy and improved simplicity in practical terms. The proposed models utilizing the artificial intelligence applications encourage the ultimate rehabilitation policies to be proposed and improved code provisions to be developed for contemporary structures. [ABSTRACT FROM AUTHOR]

With the increasing of tunnel mileage, one of the most vital problems of broad-scale structures is the intelligent identification and location of structural defects, which require massive data storage capacity and high data processing efficiency. The full-field point cloud data collected by terrestrial laser scanning (TLS) can be extracted to construct three-dimensional measured models more accurately, therefore, the fusion of TLS and the finite element method (FEM) is particularly beneficial to the deformation analysis of tunnel structures. This paper combines numerical simulation and full-field measurement to interactively verify the reliability of deformation analysis based on FEM simulation and point cloud processing. The innovation of this paper is that a three-dimensional FEM is validated through the measured point cloud data of the tunnel structure. The result of this study indicated that FEM simulation and the structural health monitoring analysis are consistent. [ABSTRACT FROM AUTHOR]

In order to further improve the crashworthiness, this paper introduces hierarchies and gradients into thin-walled structures, and designs a new type of rhombic hierarchical gradient multicellular hexagonal tube (RHGMHT), which has the characteristics of hierarchies and gradients in structure. Experimental analysis showed that the mean crashing force (MCF) of 2nd order RHGMHT is greatly improved, and its crushing force efficiency (CFE) is increased by 104.91% compared with 0th order hexagonal tube (HT). The finite element model validated by the experiment is simulated to analyze its deformation mechanism and crashworthiness. Compared with other structures at the same mass, RHGMHT has higher specific energy absorption (SEA) and no increase in initial peak force (IPF). The parametric analysis shows that the SEA of 2nd order RHGMHT is 57.89% higher than that of the 0th order HT. In addition, increasing the mass of the structure can further improve the plateau force, but the IPF also increases with the mass. By comparing the thickness ratios of different rib plates, the analysis shows that different rib plate thicknesses significantly affect the deformation mode and thus the crashworthiness of the structure. Finally, according to the simplified super folded element (SSFE) theory, the MCF theoretical prediction model is established. The results show that the MCF predicted by theory is in good agreement with the MCF obtained by numerical simulation. The hierarchical gradient design proposed in this paper provides a certain guiding significance for the design of new energy absorbers. [ABSTRACT FROM AUTHOR]

According to the traditional blasting theory and practice, the slotted cartridge blasting can form straight cracks extending along the slot direction and achieve directional fracture. In this paper, an experimental study has been carried out to determine the influence of incident stress waves and reflected stress waves. Under the influence of stress waves, the propagation path of the main crack in slotted cartridge blasting is not straight, and the directional fracture effect is inadequate. Under the experimental conditions in this paper, the propagation of main cracks mainly experienced three stages: directional propagation stage, counterclockwise deflecting propagation stage, and clockwise deflecting propagation stage. The difference between incident stress waves and reflected stress waves results in the difference in the deflecting direction, transforming the main crack into a wing shape. In rock roadway drilling and blasting engineering, the propagation path of main cracks produced by peripheral boreholes using the slotted cartridge blasting is also affected by the incident and reflected stress waves. These stress waves are inevitably generated from free faces and adjacent boreholes; however, these are rarely considered in the design of blasting parameters. Therefore, the design and optimization of blasting parameters considering the interaction of stress waves and main cracks in the slotted cartridge blasting need to be further developed. [ABSTRACT FROM AUTHOR]

AbstractSeismic surface waves possess detrimental characteristics of low frequency and significant amplitude, posing a threat to buildings and structures. This paper proposes a novel combined wave barrier, referred to as the periodic WIB-trench barrier, which is designed specifically for the purpose of isolating seismic surface waves. The periodic WIB-trench barrier consists of wave impeding blocks (WIB) and infilled trenches. The surface wave bandgaps of the periodic WIB, infilled trench, and the combined wave barrier have been compared, while the vibration modes of these three barriers have also been acquired to reveal the mechanism of the bandgaps of surface waves. Subsequently, a finite barrier transmission model has been established to analyze the vibration isolation performance of the periodic WIB-trench barrier in both the frequency domain and time domain. The results demonstrate that the proposed combined wave barrier exhibits larger bandgap widths and lower boundary frequencies when compared to the periodic WIB and periodic infilled trenches. Specifically, the bandgaps of the periodic WIB-trench barrier ranges from 4.5 to 6 Hz, 9.5 to 12.8 Hz, and 15 to 20 Hz. Through the confinement of surface wave energy within the barrier unit cells or the conversion of surface waves into body waves, an effective vibration mitigation approach proposed in this paper can be achieved. This research offers a novel perspective on the design of periodic barriers for seismic surface waves isolation purpose. [ABSTRACT FROM AUTHOR]

The difficulties in establishing an analytical model for plain woven fabric composites (PWFC) and its implementation are well-accepted due to the complexity of yarn architecture, approximations assumed, and lack of experimental validations. In this paper, a practical engineering approach is proposed to predict the tensile properties of PWFC. The approach assumes PWFC as cross-ply, the undulation angle an elliptical shape. The approach tremendously simplifies the calculation keeping a close agreement with the tensile experimental results of PWFC. The approach is remarkably compatible with other theoretical models and experiments that existed in the literature. [ABSTRACT FROM AUTHOR]

This paper presents a numerical method to solve the non-linear vibration problem of composite structures made of many unidirectional fibers/matrix layers. To take into account damping properties of structures, fractional derivative Zener model for complex moduli is used in each layer. The frequency dependence of these models leads to a non-linear vibration problem. To solve it, a High Order Newton (HON) solver based on homotopy and perturbation techniques is proposed. Thus, the initial non-linear problem turns into a set of linear systems, easier to solve. Numerical results obtained by the HON solver are compared with experimental and numerical results of literature. [ABSTRACT FROM AUTHOR]

AbstractThere are many types of lenses in tailings ponds that have important influences on stability. Lens types of more than 150 tailings dams were analyzed in China’s severely cold regions, cold regions, hot summers and cold winters (the civil building thermal design code (GB50176-2016)). The mechanism of lens formation is discussed in this paper. Triaxial tests of tailings were carried out with fine mud tailing lenses, notched lenses, ice lenses and soft plastic soil lenses. Moreover, a three-dimensional triaxial test model with a flexible boundary is constructed to study the influence of different lenses on the mechanical properties of the tailings. The lens can change the failure mode of the tailings. These faults can change the dilatancy failure of tailings to failure along the “lens-tailings” interface. With increasing confining pressure, the ability of the lens to weaken the strength of the tailings increases. At 500 kPa, the strengths of the samples with fine mud tailing lenses, notched lenses, ice lenses and soft plastic soil lenses are 95.28%, 88.79%, 76.99% and 5.49%, respectively, of those of the sample without lenses. In addition to soft plastic soil lenses, other lenses provide space to accommodate the deformation of tailings, thereby reducing the bulk strain of tailings. The conclusions of this study can provide theoretical support for studying the failure mode of tailings dams under the influence of lenses and improving the local stability of tailings ponds. [ABSTRACT FROM AUTHOR]

AbstractThe growing global demand for sustainability has led bio-sourced fibers to be identified as an alternative to synthetic fibers. In this paper, micromechanics and multiscale modeling approaches are used to predict the thermomechanical behavior of thermoplastic (polypropylene PP matrix) composites reinforced with four different natural fibers: flax, vegetal-technic, woodforce and a hybrid of flax and vegetal-technic, for random and aligned fiber orientations. Different microstructural orientations (0°, 45°, 90° and random) are generated and computed using the finite element method. Besides, an analytical modeling based on the Mori-Tanaka homogenization scheme is used to validate numerical results. The thermomechanical results showed a good agreement between the numerical computation and analytical approach for the aligned fiber orientations. In addition, the mechanical results obtained for the random fiber orientation remain in agreement with the experimental and analytical results reported in the literature. Besides, a user-defined material (UMAT) is implemented on tensile, compression and shear specimens. Through a virtual characterization, a material card for a 50% volume fraction of fiber is established for a flax-PP composite. Finally, an application made on a quadcopter frame, gives the failure indicators under thermomechanical loads at −20 °C and 55 °C, demonstrating the capability of plant fibers composites to withstand extreme conditions. [ABSTRACT FROM AUTHOR]

AbstractConcurrent multiscale damage analysis is still a challenge in woven composite structural level due to its extremely high computational cost. In this paper, a novel efficient concurrent multiscale framework for woven composite structures is proposed based on data-driven reduced order model, and the multiscale damage behavior of 4-H satin weave carbon/carbon composites is investigated using this framework. The elastic properties of yarn are predicted using the information from fibers and matrix. The mesoscale anisotropic damage behaviors of the open hole plate under uniaxial tension are simulated using this framework. The simulation results have good agreement with the experiment. [ABSTRACT FROM AUTHOR]

A novel damage tolerance design method of discrete interleaved toughening for laminated composite was proposed. In this paper, discrete thermoplastic Polyamide-6,6 (PA 66) films were deployed at between the selected adjected layers, and three toughening dimensions were considered. Besides, three impact positions of specimens were tested under 5 J, 10 J, and 15 J, respectively. The impact behavior and compression after impact (CAI) of specimens were discussed and compared. Experimental results showed that delamination damage was suppressed in the process of propagation outwards across the toughened region, and the path of delamination crack propagation was changed and swerved. Therefore, the delamination damage projected area (DDPA) of all specimens were reduced by 21.09%–62.85%, compared with the non-toughened plate (base plate). In addition, the finding demonstrated that CAI strength is influenced by the delamination position and DDPA. The proposed method could improve the CAI strength by suppressing delamination and swerving the propagation path of delamination. Moreover, the CAI strength of all toughened plates were improved by 16.35%–61.94% in contrast to the related base plates. [ABSTRACT FROM AUTHOR]

This paper discusses the fracture analysis of FG structures reinforced by CNT exposed to thermo-mechanical load by means of the XIGA framework. The equivalent properties of functionally graded structures reinforced by CNT (SWCNT & MWCNT) are computed using micro-mechanics models. The volume fraction of CNT has an impact on the mechanical and thermal properties. Then, a preexisting crack is considered in the CNT reinforced FG square structure to perform the fracture analysis. The SIFs are calculated by the interaction integral method. It is noted that delaying of the fracture is possible with the increase of CNT content in FG structure. [ABSTRACT FROM AUTHOR]

This paper presents a multiscale progressive fatigue damage model to predict the fatigue life of composite laminates. The multi-level damage model was employed considering the interfacial debonding effect, and effective material properties were calculated through homogenization. Damage variables and damage slopes were defined at the constituent level, and fatigue damage parameters were obtained using the residual stiffness data with the chaotic firefly algorithm. The model was implemented into ABAQUS, then validated with flat-bar and pin-loaded specimens of AS4/3501-6 composite. The numerical results corresponded well with the experimental data and showed the ability to capture the failure propagation of composite laminates. [ABSTRACT FROM AUTHOR]

Despite the common use of the standard linear solid model (SLSM) in viscoelasticity, the physical significance as well as the difference between the Maxwell and Kelvin forms of SLSM are still not clear. This paper demonstrates that each parameter of those two models has its specific physical meaning, and introduces the relationships allowing the transformations between those parameters. Regardless of their physical significance, those two models are equivalent in terms of their mathematical properties. Hence, no matter which model is chosen, consistent analysis results can always be obtained as long as the physical meaning of each parameter is accurately interpreted. [ABSTRACT FROM AUTHOR]

AbstractThe dynamic response of concrete structures reinforced with nanocomposites to supersonic airflow represents a critical aspect in aerospace and defense applications, necessitating accurate predictive models for enhanced structural integrity and performance. In this study, we introduce innovative deep neural networks (DNNs) as a novel approach to predict the dynamic behavior of such structures under supersonic airflow conditions. Traditional modeling techniques often face challenges in capturing the intricate interactions between material properties, structural geometry, and airflow dynamics, particularly in the presence of nanocomposite reinforcements. DNNs offer a promising solution by leveraging their ability to learn complex patterns and nonlinear relationships from extensive datasets. This paper presents a comprehensive framework for developing and deploying DNN-based models for dynamic prediction, encompassing network architecture design, training strategies, and data preprocessing techniques tailored to the unique characteristics of nanocomposite-reinforced concrete structures. Through a series of case studies and comparative analyses, we demonstrate the effectiveness and accuracy of DNNs in capturing the dynamic response of such structures to supersonic airflow, including phenomena such as vibration, flutter, and aerodynamic instability. Furthermore, we discuss the potential advantages and challenges associated with the adoption of DNNs in aerospace and defense applications, including model interpretability, computational efficiency, and data requirements. Finally, we outline future research directions and opportunities for further advancing the application of DNNs in addressing dynamic challenges in aerospace engineering and beyond. [ABSTRACT FROM AUTHOR]

AbstractEngineering problems, such as fire and explosion caused by mechanical damage, have restricted the further development of lithium-ion batteries (LIBs). The paper aims to present an effective method for studying the impact responses of cylindrical LIBs under localized impact loadings. An impact model in which the cell is simplified to a beam is developed considering the interaction between bending and stretching. The membrane factor (fn) of the beam with a circular cross-section is introduced, and then the motion control equations for the cell with large deformation are derived. The accuracy of the theoretical method is verified based on the results from the mass block impact experiment and finite element simulation. A method for cell failure detection is established based on the force-displacement-voltage response from the impact experiment. It is shown that higher impact velocities and smaller punch widths increase cell deformation. Moreover, a larger punch mass results in greater displacement when the impact energy remains unchanged, and the strengthening tendency increases with the punch width. The research will provide theoretical guidance for the safety assessment and dynamic optimization design of LIBs. [ABSTRACT FROM AUTHOR]

AbstractAfter conducting three World-Wide Failure Exercises (WWFEs), it has become apparent that existing strength theories or criteria have certain deficiencies, and no single theory can accurately match all experimental results. As a result, there is a growing focus on the uncertainties present in the macrocosm test data of composite materials. The paper introduces the concept of uncertainty into the collection of test data for the classical Tsai-Wu failure criterion and Hashin criterion. The method proposed involves fitting the coefficients of the failure criteria by treating experimental data as random variables, a technique that diverges significantly from the conventional method of using composite allowable values to define these coefficients. It also uses the probability of success as a constraint and defines the fitted error as an optimization objective. Monte Carlo sampling is employed to perform a reliability analysis, and six sigma is used for a reliability-based optimization of the failure criteria. The Multi-Island Genetic Algorithm is utilized to search for the optimal value. The approach presented in this study provides the ability to predict future failures in composite materials by considering the uncertainty of the test data. By incorporating uncertainties into the analysis and design process, a more accurate and reliable assessment of the performance of composite materials can be achieved. Moreover, there seems to be a significant difference in the fitting error between the mean data and the normal distribution data. Additionally, when Hashin criterion is modified, the test data matches the failure envelope more closely and the degree of fit between the experimental data and the failure envelope is higher. [ABSTRACT FROM AUTHOR]

AbstractThis paper carried out a theoretical research on multi-physics coupling problems of functionally-graded lead-free piezoelectric rectangular thin plates. Firstly, the perturbation theory was used to study the bending problem of functionally-graded lead-free piezoelectric rectangular thin plates, and the nonlinear governing equations for this bending problem were established. Then, the three piezoelectric coefficients reflecting the piezoelectric property were taken as the perturbation parameters, and the nonlinear governing equations were transformed into multiple sets of linear equations by the multi-parameter perturbation method. Finally, the solutions of these linear equations were solved by the semi-inverse solving method. Based on the finite element simulations, the effectiveness of the perturbation solutions obtained here was verified. The research results showed that it was reasonable to choose three piezoelectric coefficients as perturbation parameters, which was accord with the basic idea of perturbation theory. The analysis results indicated that there was a cross transfer relationship between external loads and perturbation solutions of every order, which could be used to simplify the perturbation expansion. Moreover, the deformation of the functionally-graded lead-free piezoelectric thin plate was less than that of the functionally-graded thin plate, that is, piezoelectric properties in lead-free piezoelectric materials had a piezoelectric enhancement effect. [ABSTRACT FROM AUTHOR]

AbstractThe pile-caisson composite structure (PCCS) is an innovative underground anchorage foundation used to support large-span suspension bridges. This paper presents the displacement and the load transfer mechanism of the PCCS. The bearing responses of each individual pile in the PCCS were analyzed employing the finite element method, which was verified by the model test results. The peak bending moments borne by pile P11 and pile P53 in the PCCS exhibit the most significant disparity, with a difference that can reach up to 133.97%. Moreover, a parametric study utilizing numerical simulations indicates that augmenting the pile diameter and length, while reducing the pile spacing, can mitigate the displacements of the PCCS. However, there is an upper limit (i.e. S = 3.5d) for the pile spacing beyond which marginal benefits could be obtained. The findings of this study can provide guidance for the design and construction of the PCCS. [ABSTRACT FROM AUTHOR]

AbstractThis paper studies the free vibration and harmonic response of Functionally Graded Graphene/Epoxy composite plates, considering the First Order Shear Deformation Plate Theory. The weight fraction of graphene variation along the thickness direction with graphene homogeneous dispersed in a polymer matrix. The effective Young Modulus of the plate is predicted by a new micro-mechanical model. The model includes the aspect ratio and weight fraction of nanoplatelets embedded into the matrix. The modal and harmonic of Graphene/Epoxy plates are obtained by the Boundary Element Method formulation for composite plates. The Young modulus calculated from the proposed micro-mechanical model highly agrees with those obtained from experimental results reported in the literature. Results demonstrate a high correlation of the micromechanical model with experimental results and other analytical models. Graphene weight fraction and ratio aspect increase the effective Young modulus of the composite. Boundary Element results show high agreement with Finite Element solutions. Numerical results for modal and harmonic analysis show concentrating graphene near the top and bottom surfaces of the plate is the most effective way to reinforce the plate for increased natural frequencies. The results demonstrate the BEM formulation and micromechanical model can be used as reliable engineering tools for the vibrational analysis of functionally grade graphene composite plates. [ABSTRACT FROM AUTHOR]

AbstractThree-dimensional orthogonal woven composites (3DOWCs) offer significant advantages in engineering applications due to their designability for spatial structures and ability to minimize delamination damage. As primary load-bearing structures, 3DOWCs are always in preloading conditions prior to potential low-velocity impact (LVI) events. This paper presents a macro-meso coupled finite element (FE) model for investigating the response of preloaded 3DOWCs subjected to LVI. The accuracy of the proposed numerical model is validated by a comparison with available experimental data in terms of impact performance and damage state. Furthermore, the influence of preload and impactor shape on the LVI performance of 3DOWCs is examined, and detailed analysis is provided regarding the associated damage mechanisms. This study offers a transferable numerical approach that can be applied to studying the coupling problems of LVI and preload in other textile composite structures. [ABSTRACT FROM AUTHOR]

AbstractIn this paper, impact attenuation and blast-wave mitigation are effectively realized by the dissipative stratified metamaterials with negative mass mechanism due to the coupling of the different resonators. To create a broad bandgap of the metamaterials, the dispersion curve and effective negative mass property are investigated. It is found that the coupling effect of different resonators produced by the relative movement of different main masses can create a broad bandgap and make the original bandgap by starting with a lower frequency, and thus impact input waves could be blocked effectively. Simulation results show that a stratified elastic metamaterial containing 25 units can reduce the amplitude of the load by two thirds under impact loading and almost completely impede its further propagation. Furthermore, the bandgap is broadened by optimization of the structure parameters and dissipative coefficient for blocking transient shock waves propagation. It is shown in numerical experiment that the wider bandgap produced by the new elastic metamaterials can effectively absorbed the energy of the blast and impact waves. Therefore, the results of this study provide a remarkably novel strategy for the design of new blast-resistant materials. [ABSTRACT FROM AUTHOR]

Piezoelectric quasicrystals have attracted the tremendous attention of researchers for their unique properties. In this paper, the semi-analysis solutions of the functionally graded multilayered two-dimensional decagonal piezoelectric quasicrystal plates are investigated for mixed boundary-value problems. Based on the quasicrystal linear elastic theory, the state-space method is employed to derive the state equations composed of partial differential along the thickness direction. The differential quadrature method is utilized to discretize state variables to satisfy the mixed boundary conditions in the horizontal plane. Different from the conventional propagator matrix, a new propagator relationship is proposed to study numerical instability caused by extensive discrete points. Comprehensive numerical results are shown for the sandwich quasicrystal plate with four different stacking sequences. The numerical results reveal the effect of the functional gradient index factors, and boundary conditions on the electric potential, electric displacements, stresses, and displacements under the mechanical/electric loadings. [ABSTRACT FROM AUTHOR]

Acoustic black hole (ABH) with extraordinary properties of wave manipulation and energy focalization has been drawing growing attention in mechanical metamaterial, and the development of topological phenomena provides a novel way for investigation of ABH characteristics. This paper explores the physical mechanism of dispersion curves of three metabeams with embedded periodic ABHs and studies the topological phenomena of the compound metabeam for energy localization. First, the mass-spring models are employed according to lattice dynamics method to clarify the formation mechanism of bandgaps and the effect of the parameters on dispersion relation. Meanwhile, the diatomic mass-spring model provides an analytical framework to investigate the band inversion and the displacement distribution of topological states. Furthermore, numerical analyses are carried out to investigate the band structures, eigenmodes, transmission, and the achievement of topological interface state by proposed compound metabeam. The adjustment of structural parameters, changing the mass and stiffness of the mass-spring model, can broaden the bandgap in low frequency for better vibration attenuation performance. Besides, the modal formation in low frequency is explained by masses vibration distribution. The correctness of the method is verified by comparing the transmission numerically with previous experiments. This work enriches the existing knowledge of ABH on wave manipulating and energy harvesting. [ABSTRACT FROM AUTHOR]

This paper presents a numerical framework for implementation of cohesive zone model with smoothed floating node method (SFNM) for failure analysis of quasi-brittle materials. The nonlinear behavior of material inside the fracture process zone in front of the crack tip is modeled with a potential-based intrinsic cohesive zone approach. Here, SFNM is used to represent the kinematics of crack and the crack front inside the domain without the requirement of remeshing and discontinuous enrichment functions during crack growth, hence resolves the issues associated with the existing discrete numerical methods. A strain smoothing technique is adopted over the domain through which classical domain integration changes to line integration along each boundary of the smoothing cell, hence derivative of shape functions are not required in the computation of the field gradients, thus resolves the issue of element distortion. The proposed numerical framework is firstly verified using the patch test of the two-dimensional specimen under mode I and mode II loading conditions and subsequently extended for solving the two-dimensional standard fracture problems. The effectiveness of the proposed framework is checked by comparing the computational results with the available literature results. [ABSTRACT FROM AUTHOR]

AbstractThe industrial applications of singly curved shells significantly increased in modern engineering structures and several of those have non-uniform boundary conditions. A detailed relative performance study for the non-uniformly restricted shells can popularize their use further among practicing engineers. The literature review confirms that there is dearth of research studies in this area. This paper aims to fill up that void. A finite element code of C0 continuity combining von-Karman strains, first order shear deformation theory and eight noded curved elements is proposed. Wide variety of shell problems are solved for different boundary conditions, laminations, radii of curvatures, thickness, and plan dimensions. Relative nondimensional deflections and fundamental frequencies are studied for varying boundaries. It is concluded that although the performances of shells are comparable for different boundaries, the shells with CCCC edges offer better performances. These shells should have longer span along the arch direction, a symmetric 16°/-16°/-16°/16° laminate, side/thickness = 100, and radius of curvature/plan = 0.75 to achieve minimum deflection and maximum fundamental frequency. [ABSTRACT FROM AUTHOR]

AbstractThis paper evaluates Enhanced Vibrating Particle System (EVPS) and Grey Wolf Optimizer (GWO) algorithms for Reliability-based Design Optimization (RBDO) of steel frames. The two-loop RBDO method minimizes frame weight while satisfying strength, drift, and reliability constraints, considering uncertainties in material properties and loads. Both EVPS and GWO effectively reduce structure weight and ensure required reliability levels, demonstrating their applicability in sustainable steel frame design. [ABSTRACT FROM AUTHOR]

In this paper, the contact heating technology was combined with the warm and hot stamping process of high-strength aluminum alloy, and the corresponding experimental device was developed. For the contact heating-warm stamping process, it's found that as the heating temperature increases, the mechanical properties of the parts first decrease and then increase, while the springback decreases. Meanwhile, for the contact heating-hot stamping process, it's found that the aluminum alloy sheets experience large plastic deformation during contact heating, resulting in the refinement of microstructure and the increase in dislocation density, and the performance of the formed parts is improved. [ABSTRACT FROM AUTHOR]

In this paper, the contact behavior of silicone rubbers under spherical and conical indenters is investigated by simulation and experiment. The accuracy and applicability of seven hyperelastic constitutive models are discussed for the contact behavior of silicone rubbers. The stress-strain curves obtained by uniaxial tension/compression experiments are used to fit parameters of hyperelastic constitutive models. Indentation experiments are carried out to compare with simulation results. The fitting accuracy of constitutive models under different strains is analyzed. It is found that the constitutive parameters fitted by the uniaxial compression experiments are the best for simulating the contact behavior of silicone rubbers. [ABSTRACT FROM AUTHOR]

AbstractThe increasing interest in adhesives, such as pressure-sensitive adhesives (PSAs), is often held back by uncertainties regarding their long-term behavior, which includes creep behavior. However, little information exists in the literature regarding creep behavior of PSAs. In this paper, a unified phenomenological creep model for PSAs is applied in SLJs for static and cyclic creep, seeking to develop a tool to predict creep behavior of PSAs. The model was validated by comparing the predicted creep curves with experimental data. It captured the three creep phases and predicted the creep curves for different stresses and temperatures, which is uncommon in literature. [ABSTRACT FROM AUTHOR]

AbstractIsogrid structures offer an excellent balance between mass and rigidity, making them a crucial component in various industrial sectors. However, like all types of structures, isogrids are susceptible to performance degradation due to uncertainties in geometrical and material parameters arising from manufacturing errors and exposure to critical service environments. This paper addresses the effects of parameter uncertainty on the structural behavior of isogrid tube structures. To this end, a Sobol index is employed to assess the sensitivity of the tube’s natural frequency, axial buckling, torsional buckling, and overall mass to three geometrical and one material parameter, each subject to a 10% random variation. The data for this analysis were generated using a parametrized numerical model specifically developed for this purpose. To optimize computational costs further, an artificial neural network predictive model is proposed, which accurately replicates the behavior of the numerical model. The results indicate that the angle between helicoidal ribs is the most influential parameter. [ABSTRACT FROM AUTHOR]

AbstractThis paper demonstrates a thorough examination of the bending behavior of sandwich concrete building structures that are reinforced with graphene nanoplatelets (GPLs). The analysis is confirmed using a machine learning technique. Sandwich structures have notable benefits in terms of strength, longevity, and thermal insulation, making them well-suited for many building applications. Integrating GPLs into the concrete matrix improves the mechanical characteristics and performance of these structures, especially in terms of bending behavior. This study utilizes a machine learning technique to verify the characterization of the temporary bending behavior of a concrete building structure reinforced with graphene nanoplatelets. The approach utilizes a dataset consisting of simulated bending data to create a prediction model that can reliably estimate the temporary bending response of the reinforced structure under different loading situations. The machine learning algorithm’s effectiveness and dependability in optimizing the design and performance of graphene nanoplatelets reinforced sandwich concrete building structures are demonstrated through validation against simulated results. This provides engineers and designers with a powerful tool. This study enhances the comprehension and use of machine learning approaches in analyzing and designing sophisticated structural materials and systems. [ABSTRACT FROM AUTHOR]

ABSTRCTTo enhance the bird strike resistance of fixed-wing aircraft wings, a combined computational approach integrating nonlinear solid mechanics and fluid dynamics was employed to analyze the bird strike characteristics of both traditional aluminum alloy skins and novel composite materials skins. Additionally, a standardized procedure was established to simulate aircraft structural damage more comprehensively, swiftly, and accurately during bird strikes, along with diagnostic analysis of flow field changes near the wing post-impact. This method not only quantifies wing strength damage but also establishes corresponding relationships between damage severity and aerodynamic performance degradation. The research findings indicate that the deformation of composite material skin wings is only a quarter of that of aluminum alloy skin wings. Composite material skins absorb less harmful energy compared to aluminum alloy skins, with consistently lower stiffness reduction rates at various bird strike velocities. Velocity distribution on deformed wings with composite material skins exhibits minimal deviation compared to normal wings, thereby preventing airflow separation. The research results provide more comprehensive guidance for the selection of materials for bird strike resistance of aircraft wings and the airworthiness evaluation after bird strikes.This paper establishes a standardized procedure that enables a more comprehensive, faster, and higher-precision simulation of structural damage to the aircraft during a bird strike on the wing and allows for the diagnostic analysis of the flow field changes near the wing after bird strike.By coupling nonlinear solid mechanics and fluid dynamics computational methods, the aerodynamic performance of the wings at different angles of attack post-deformation is investigated. This approach not only quantifies the strength damage to the wings but also establishes corresponding relationships between the degree of damage and the deterioration in aerodynamic performance.The research yields insights into the aerodynamic performance degradation patterns with varying angles of attack for both composite material skin and aluminum alloy skin deformed wings. These findings can serve as valuable references for pilots in emergency situations, aiding in their decision-making regarding aircraft control. [ABSTRACT FROM AUTHOR]

AbstractFlexible rolling (FR) is a novel process for manufacturing doubly curved shallow shells with various shapes based on a pair of small-diameter bendable rolls. In this paper, the fundamental reason for bi-directional bending of the sheet metal in FR is explained. For the purpose of predicting the forming radii in the transverse and longitudinal directions more effectively, the exit velocity is divided into linear velocity and interference velocity, with the latter so small as to be considered to cause only elastic deformation of the sheet. The theoretical calculation model of the pre-curvature radius resulted from linear velocity is established. Using the mechanical theory of the doubly curved shallow shell, the transverse and longitudinal curvature changes caused by the interference velocity are derived and solved by the analytical approach, which are added to the transverse and longitudinal pre-curvatures respectively so that the actual curvature radii are obtained. In order to verify the reliability of the proposed shape prediction method of FR, numerical simulations and forming experiments for convex and saddle-shaped parts are carried out. Through measurement and comparison, it is found that the simulated and experimental results are extremely consistent with the theoretical data. Besides, the effect of important parameters on elastic deformation is investigated by means of the deduced formulas. [ABSTRACT FROM AUTHOR]

In this study, a high-strength bolted prefabricated concrete beam-column junction is presented, and the prefabricated concrete beam-column joint parts are put through eight quasi-static tests. The axial compression ratio and the steel plate hoop thickness were used in extended parameter research using finite element software to completely examine the seismic performance of the construction. According to the findings, this node's ductility coefficient ranges from 2.57 to 3.69, which is bigger than 3. The specimen loses part of its bearing capacity and constantly loses ductility as the axial compression ratio rises. The failure displacement of the specimen decreases with an increasing axial compression ratio, but the yield displacement of the specimen is very slightly affected by the axial compression ratio. This node has an excellent energy dissipation capacity despite having a low viscous damping coefficient between 0.2 and 0.4, and when the axial pressure ratio rises, the capacity grows in response to the elevated pressure. Despite this, the energy consumption of the beam-column member is not significantly affected by the steel plate hoop thickness. Additionally, according to the variable-angle truss-arch model and taking into account the representation of the truss-arch model under different conditions, this paper presents the equation for the shear load capacity of diagonal sections of prestressed high-strength spiral hoop-restrained concrete beams under various conditions. [ABSTRACT FROM AUTHOR]

The analytical and numerical treatments of horizontal and vertical forced time-harmonic vibrations of a rigid circular foundation in a transversely isotropic elastic half-space ground are presented. A complete discussion on the boundary conditions and elastic wave propagation due to horizontal and vertical vibrations of the foundation on the half-space is presented and a comparison is made with the full-space problem. With the aid of appropriate dynamic Green's functions reported in the literature, the horizontal and vertical vibrations of the foundation are treated analytically, and the results are expressed in terms of the solutions of several Fredholm integral equations. For these two vibration modes, the relations for the contact normal and shear stresses, the resultant forces acting on the foundation, and the dimensionless impedance and compliance functions are given. To validate the analytical formulations, the results obtained in this paper are reduced to static responses for transversely isotropic half-space, and to dynamic responses for isotropic half-space; and compared with the results reported in the literature. An efficient numerical procedure is presented to evaluate the semi-infinite integrals appeared in the analytical solutions utilizing some features of the Mathematica software. The Fredholm integral equations and impedance and compliance functions are solved and evaluated numerically using the Gaussian quadrature method. Some graphical results are provided to present the impedance and compliance functions for different transversely isotropic materials. The effects of material anisotropy, as well as the frequency of excitation on the responses are discussed. The differences between vibrations of rigid foundations in the half-space and full-space mediums are emphasized in view of the Rayleigh wave propagation. Moreover, the difficulties related to numerical procedures needed for handling the strong singularities due to propagation of Rayleigh waves in the half-space media are presented. [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]

AbstractThe nonlinear geometrically exact (GeX) hybrid-mixed four-node solid-shell element under non-conservative loading, developed in the companion paper, is here extended to the stress analysis of functionally graded material (FGM) shells. The term GeX means that the middle surface is described by analytical functions, including spline functions, and, therefore, the coefficients of the first and second fundamental forms can be taken exactly at element nodes. The FGM solid-shell element formulation is based on the choice of N sampling surfaces (SaS) parallel to the middle surface and located at Chebyshev polynomial nodes within the shell as well as on the outer surfaces, to introduce the displacements of these surfaces as basic unknowns. The use of Lagrange polynomials of degree N–1 in the distributions of displacements, strains, stresses, and elastic coefficients through the thickness of the shell leads to an efficient 3N-parameter shell formulation. To develop the FGM four-node solid-shell element based on the hybrid-mixed method, in which strains and stresses are utilized as primary variables, the Hu-Washizu variational principle is applied. Due to the analytical integration used to evaluate the tangent stiffness matrix, the developed FGM solid-shell element subjected to displacement-dependent loads shows superior performance in the case of coarse meshes and allows the use of only one load step in most of the considered benchmark problems. It has been established that the difference between the second Piola-Kirchhoff and Cauchy stress tensors in non-conservative problems for FGM shells undergoing moderately large strains can be significant. [ABSTRACT FROM AUTHOR]

AbstractIn this paper, the Gyroid triply periodic minimal surface is prepared by liquid crystal display photopolymerization technology, and 10 models of the periodic parameter T in [1/5, 2] are designed. Using the method of finite element method and experimental verification, when T = 1/3, there are fewer stress concentration areas on the Gyroid surface, the number of grids is moderate, the compression crush rate is the smallest, and the porosity error is reasonable. Through the microscopic morphology, it is found that the surface, after printing, forms gear shape and resin residue so that the actual volume is larger than the theoretical volume, and the porosity is minor. Keeping periodic parameter T = 1/3 and porosity of 50%, four kinds of Gyroid surface structures were designed by changing the parameter surface offset, wall thickness, offset thickness, and gradient arrangement. The effects of different loading directions on its mechanical properties, deformation behavior, and energy absorption were discussed through compression experiments. The results show that the vertical load is applied to form a fault zone from the upper left angle to the lower right angle of 45°, and the parallel load is applied to create a fault zone from the upper right angle to the lower left grade of 45°. When the load is used in the vertical direction, the energy absorption and energy efficiency of the surface offset Gyroid surface are the largest. When the load is applied in the parallel order, the energy absorption curves of the four structures change similarly, and the deformation amplitude of the wall thickness Gyroid surface during the compression process is relatively stable. The energy efficiency of gradient arrangement Gyroid surface increases fastest in the compaction stage. [ABSTRACT FROM AUTHOR]

AbstractThis paper investigates the effects of multiple materials configurations on the buckling performance, total mass, and manufacturing cost of an existing omega stiffened composite panel. The buckling response of omega stiffened composite panel is predicted and verified using available data in literatures. The multiple materials are introduced into the omega stiffened composite panel. The material distribution, stacking sequences of panel skin, T sub-stiffeners and omega sub-stiffeners are optimized to improve the critical buckling load with reducing the total mass and manufacturing cost. During the optimization process, three classical loading conditions of the stiffened panel are considered, while ensuring compliance with the constraints imposed by ply manufacturing. A generalized optimization design framework for stiffened panels is employed, and NSGA-II algorithm is utilized to achieve the optimum design of stiffened panels. Results demonstrate that the introduction of multiple materials to the omega stiffened composite panel can lead to improved buckling performance, along with reduced manufacturing cost and total mass. Additionally, the proposed multiple-material optimization design framework can be further applied to the structural design of other types of stiffened composite panels in the future. [ABSTRACT FROM AUTHOR]

A novel high-temperature resistant carbon fiber/bismaleimide resin composite shell is proposed and its bistable characteristics are studied in megathermal environment. Bistable structures are prepared with epoxy resin composites conventionally, which prone to undergone glass transition at high temperature. The study of high-temperature resistant bistable structure become necessary to suit aerospace field. In this work, the effect of elevated temperatures and different ply angles were investigated on curvatures and snap behaviors of carbon fiber/bismaleimide resin composite bistable shells through experiment and finite element analysis. These results provided significant understanding of morphing behaviors for the carbon fiber/bismaleimide bistable structure in megathermal environment. A novel high-temperature resistant carbon fiber/bismaleimide resin composite shell is proposed and its bistable characteristics in megathermal environment are studied in this paper. Bistable structures are prepared with epoxy resin composites conventionally, which prone to undergone glass transition at high temperature. The study of high-temperature resistant composite bistable structure become necessary to suit the actual working conditions. In this work, the anti-symmetric bistable shells with different ply angles (40°, 45°, 50°) are fabricated using T700/QY8911 prepreg. The effect of elevated temperatures and different ply angles were investigated on the principal curvatures and twisting curvatures of carbon fiber/bismaleimide resin composite bistable shells through experiment and finite element analysis. The snap behaviors of the bistable shells with different ply angles at different temperatures were obtained. Furthermore, a novel two-point tensile loading method was applied to the snap-back processes of carbon fiber/bismaleimide resin composite bistable shells with the subtended angles greater than 180°. It is noticed that the bistable shells have better high-temperature stability than carbon fiber/epoxy bistable shells. These results provided significant understanding of morphing behaviors for the carbon fiber/bismaleimide bistable structure in megathermal environment. [ABSTRACT FROM AUTHOR]

In this paper, the plastic behavior of metal sandwich beams with foam-filled sinusoidal corrugation is studied theoretically and numerically. The yield criterion of foam-filled sinusoidal corrugation sandwich cross-section is established, considering the effects of metal foam strength and sinusoidal corrugation strength. Based on the yield criterion, an analytical model for the plastic behavior of fully clamped foam-filled sinusoidal corrugation sandwich beams under transverse loading is developed, considering the interaction of axial force and bending moment. Finite element calculations are carried out to verify the analytical model. The influences of geometrical and material parameters on the load-carrying capacity and energy absorption of foam-filled sinusoidal corrugation sandwich beams are discussed. The results show that, with the increase of foam strength, face-sheet thickness, sinusoidal corrugation strength, sinusoidal corrugation sheet thickness, sinusoidal amplitude, sinusoidal half wavelength and punch width, the load-carrying capacity and energy absorption of foam-filled sinusoidal corrugation sandwich beams increase. In addition, when the loading position moves from the midspan to the clamped ends, the load and absorbed energy for the same deflection increase obviously. [ABSTRACT FROM AUTHOR]

As a result of the advantages of the steel fiber reinforced concrete pavement structure, which includes high strength, high stiffness, and high stability, a large number of steel fiber concrete pavements will be used for highway construction in China. As a result, numerous cracks develop, which significantly reduces the life of the road; therefore, the study of the jointing problem is vital. As concrete research on the influence of the load transfer capacity and service life of prefabricated steel fiber reinforced concrete joints on the structural design and use function of the whole and pavement panels, the paper proposes two joint forms, tongue-and-groove and overlap. Using experiments and software, the stress and reflection of prefabricated road panels of the two joint forms are analyzed for different axial loads. The analysis reveals that the maximum tensile stress, shear stress, and deflection of the precast panels of both joint forms increase linearly as the axle load of the vehicle increases, while the service life decreases relatively. The load transfer capacity is independent of the axle load magnitude, and the load transfer capacity difference between the two types of joints is minimal and excellent. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) is a key technology for the individualized and resource-efficient production of structural components. Recent developments in manufacturing technologies enable improved quality of additively manufactured components and therefore they become more and more important in lightweight constructions. An example is the substitution of solid material by porous lattice structures. Those embedded lattice structures lead to highly weight-efficient structures. Most recent investigations focus on numerical and experimental studies to describe the mechanical behavior of lattice structures. In this paper, a method to determine analytical expressions for the axial stiffness properties of lattice structures is presented. The displacement method and direct stiffness method are used to derive symbolic parameter-dependent formulas for the axial stiffnesses and effective Young's moduli for f2cc,z, and bcc unit cells. Furthermore, an empirical approach based on Finite Element simulations is presented to describe the stiffness reduction for non-embedded or rather free lattice structures. The results are further validated by physical experiments. Stereolithography is used for specimen production. f2cc,z, and bcc lattice structures are embedded in thin-walled rectangular aluminum tubes and tested under compression load. Furthermore, lattices without a surrounding tube are tested. The analytical and empirical solutions are in good agreement with the experimental and numerical results. [ABSTRACT FROM AUTHOR]

This paper deals with the problem of the uncertainties interaction in the design parameters of a two-stage gearbox of a wind turbine. The purpose of the dynamic study is to minimize the linear displacements in order to have more stability. The uncertainty consideration using a unique parameter, allowed the identification of the influence of this latter on the dynamic response, in addition to its extreme values. The examination of multivariate parameters investigates the interaction of these parameters. Thus, the gear system dynamic behavior was studied by taking into account the uncertainty with a suggested diagram: uncoupled form to evaluate the impact of each parameter and coupled form based on the progressive interaction of uncertain dynamic parameters using the multivariate uncertainty method. For this purpose, the generalized polynomial chaos approach (GPC) was applied to simulate the dynamic behavior of the wind turbine gearbox. The obtained results were then verified using Monte Carlo simulations. [ABSTRACT FROM AUTHOR]