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Dewatering on the paper machine takes place by gravity, suction, pressing, and evaporation. Optimizing the operation of the vacuum system is important, since the electricity consumption of the vacuum pumps might be one-fifth of the total electricity consumption of the paper machine. Vacuum dewatering involves large volumes of air penetrating the web. The present study presents four sets of measured air flow rates useful for designing industrial equipment. The mass flux of air increases with increasing applied vacuum and decreases with increasing basis weight. Paper technological parameters, such as fiber size and fiber flexibility, also influence the mass flux. [ABSTRACT FROM AUTHOR]

Columns in traditional timber structures are commonly seen resting on stone bases and are very important in resisting lateral loads. This paper numerically modeled the lateral resistance of the columns combined with experimental investigation. Different numerical models were developed, based on which sensitivity analyses were performed. A practical numerical modelling strategy was further proposed and verified. The analysis results indicated that instead of material properties and contact area, the columns' lateral performance was much more sensitive to the variation of surface curvature at bottom surface. Without consideration of the surface curvature, the modeling error in the initial stiffness and peak load of a column was more than 607% and 8%, respectively. By best matching the load–displacement curves of tested column specimens, the optimal surface curvature was identified as 1/20306.5 mm−1. Then, a practical finite numerical model, characterized by the optimal curvature at the bottom surface, was proposed. This modelling method was validated by use of existing test results of traditional timber columns with different diameters and vertical compression loads. The modelling load–displacement curves agreed well with experimental curves both in terms of the initial lateral stiffness and peak load. Detailed simulation results based on the practical modelling strategy were presented and discussed. [ABSTRACT FROM AUTHOR]

AbstractTo dampen the loading sequences in the constructions, using the shear walls is recommended. Shear walls, which withstand the lateral forces (i.e., parallel to the plane of the wall) of wind and seismic activity, prevent buildings from collapsing while columns and load-bearing walls support the structure’s compression load all the way to the foundation. Besides, some new techniques are innovated for strengthening the structure like outrigger system. The steel shear walls are mostly used in the steel structures due to their high strength, ductility, and low weight. Recently, implementing Corrugated Steel Shear Walls (CSSWs) has gained more attention because they can absorb much amount of energy compared to flat steel shear walls. There are two important parameters in the CSSWs that play crucial roles in controlling their strength; corrugation geometry and orientation. Therefore, the current research paper aims to study numerically the effects of four corrugation geometries (trapezoidal, square, zigzag, and curved) with two orientations on the cyclic behavior of the CSSWs. Finite Element Analysis (FEA) is used to simulate the seismic loading conditions and finally, this procedure is validated through the comparison of the modeled flat shear wall with the experimentally published results. The difference between the peak loads of hysteresis curves obtained numerically and experimentally is about 8.5%. The stated FEA procedure in this paper can be regenerated by other researchers. The results confirmed the applicability of the CSSWs compared to the flat shear walls. Also, the vertical corrugation infill patterns result in higher strength in comparison to the horizontal ones. For instance, in the zigzag and square corrugation shapes, the plastic energy dissipation of the vertically oriented specimens (13.84 and 14.01 KJ, respectively) is higher around 7% and 29%, respectively than the horizontally oriented ones (12.9 and 10.84 KJ, respectively). Besides, the trapezoidal and curved corrugation geometries show the highest cumulated energy and plastic energy dissipation. [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]

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]

Installation of un-trenched marine pipelines on an uneven seafloor usually leads to many free-span formations along the pipeline. Also, offshore pipelines may be subjected to high longitudinal forces that can change pipeline behaviour in diverse loading states. In this paper, the effect of axial force on pipeline deformation at the free-span location and associated hazards are assessed. The excessive compressive force which can result in global buckling is evaluated. Pipeline behaviour over a depression in response to axial force variations is investigated using an analytical method presented in this research. MATLAB software is utilised for the numerical solution based on the case study data. Allowable loading state so as to avoid buckling of the pipe under a compressive load together with maximum allowable stress on pipe section based on the Von-Mises yield criterion are the two limitations considered for the pipe subjected to combined loading conditions. The results revealed in this paper specify free-span allowable lengths for several longitudinal load situations to avoid buckling failure and over stress on the pipe's section. [ABSTRACT FROM AUTHOR]

A cylindrical structure used in a space launch vehicle should endure the compressive load and it must satisfy the requirement of compressive strength. For the light-weight of the structure and improving the performance of launch vehicle, a cylindrical structure reinforced by composite lattice can be used. Therefore, a compressive strength prediction technique of the cylindrical composite lattice structure is required. In this paper, the failure criterion was proposed using the compression test of a composite lattice subelement and a simple finite element analysis for the subelement. The failure criterion was introduced using the effect of the out-of-plane and in-plane bending deformation of the rib constituting the grid of structure on the compressive strength. The subelement specimen was prepared from two different structures and the compression test was performed using several fixture jigs which can generate various deformation of the specimen. The test results and finite element model were used to examine the effect of out-of-plane and in-plane bending deformation of the rib on the compressive strength and the failure criterion which can predict the compressive strength was derived using the relationships between each parameter. The compressive failure load of the cylindrical composite lattice structure was predicted by using the proposed method and the validity and accuracy of this method were verified through a comparison of the predicted results with the test results. It was possible to predict the compressive strength within a 5% error of the experimental result. [ABSTRACT FROM AUTHOR]

The aim of this paper is to propose a new approach permitting the investigation of the 3D pore variation of kaolin K13 in relation with mechanical loading. A mechanical loading consisting of one-dimensional compression and oedometric loading is applied to a sample of centimeter scale. A postmortem protocol using scanning electron microscopy (SEM) coupled with Focused Ion Beam (FIB) was carried out to observe and then obtain a large number of slices of an extracted sub-volume from the small sample. Image analysis using a new processing method enabled the reconstruction of the observed and extracted sub-volume in the form of a rebuilt sub-volume. The segmentation of pores and particles was carried out using an approach based on machine learning and the pore space properties can be quantified. Pore morphology was identified based on two parameters namely the flatness and the elongation. Spatial orientation can also be locally determined. The proposed treatment enabled the distribution of pore size (termed Im_PSD) to be deduced and these were then compared with the results of Mercury intrusion porosimetry technique. [ABSTRACT FROM AUTHOR]

Origami crash tubes have concerned nowadays due to their superior crashworthiness behaviour by controlling the initial buckling force and collapse modes. In this paper, a new multi-layered origami pattern is proposed and fabricated, and a numerical study is performed under quasi-static axial compressive loading and validated by the experimental result of the fabricated origami crash box. To compare the energy absorption efficiency of this proposed origami tube, its mechanical responses are normalised with the conventional octagonal tube. Moreover, the crashworthiness behaviour of 64 samples is investigated for the dihedral angle 2θ, outer layer height e, and module number M in the parametric study. It is demonstrated that by increasing M for tubes with a constant value of e, the critical angle of θ decreases. By increasing the value of e for tubes; while, considering the values of M and θ constant, the mechanical responses of the tubes increase, and these trends are valid as long as θ is below the critical angle. The number of modules M, angle θ, and outer layer height e have the highest effect on the mechanical responses. Finally, the results show that by maintaining the specific energy absorption of the conventional octagonal tube, the initial peak force can be reduced about 55%. In consequence, the proposed pattern reduces the initial peak force while maintaining the specific energy absorption. [ABSTRACT FROM AUTHOR]

This paper presents a detailed numerical investigation of behavior of cylindrical tube-shaped textile-reinforced cementitious composites (TRCCs) under monotonic lateral compression loading, and experimental verification. Effects of different thickness and number of layers, different textile materials on behavior of cylindrical tube-shaped TRCCs are investigated numerically. Numerical results are obtained by finite element (FE) simulation. The deformations and damages of TRCC tubes have also been investigated and analyzed with material models identified in the FE simulation. As results of numerical analysis, load-displacement curves of TRCC tubes, basic mechanism of their deformations, and the effects of textile material and the number of TRCC layers on the deformation behavior and load-carrying capacities of the TRCC tubes were presented. In this study, it was found that TRCC tubes could be an alternative to conventional pipes due to ductility, manufacturing feasibility according to their desired load-carrying capacity, energy absorption and ductility. Analytical solution based on an energy method was also presented to estimate the strength of different type of TRCC tubes. The results obtained from the FE simulation were compared with test data of monotonic lateral compression experiment for verification. Finally, parametric analysis was conducted using geometrical variables and the effects on tube strengths were examined. [ABSTRACT FROM AUTHOR]

The main aim of this paper is to investigate the postbuckling and buckling of functionally graded graphene-reinforced composite (FG-GRC) laminated cylindrical shells strengthened by stiffeners under axial compression with the uniform temperature change effect. The stiffener design option for FG-GRC cylindrical shells under axial compression is presented and a suitably smeared stiffener technique for GRC laminated stiffener system is developed. Basing on the von Kármán Donnell shell theory, the Galerkin's procedure, and the three-term solution of deflection, the explicit forms of critical buckling and expression of load-deflection postbuckling curves relation are obtained. Effects of the GRC laminated stiffeners, the environment temperature, the graphene-reinforced parameters on the compressed buckling behavior are validated. [ABSTRACT FROM AUTHOR]

Composite sandwich panels are commonly considered as lightweight materials for structural design in many applications including automotive, aerospace and defence systems. These panels must be developed and validated for its mechanical strength characteristics under different loading conditions before deploying them for the practical application. Hence, the present paper deals with the experimental and numerical studies on composite sandwich panels subjected to quasi-static edgewise and flatwise compression loads. The composite face sheet was developed using 2 × 2 bi-directional 200GSM twill carbon fibre with hot cure benzoxazine resin. Sandwich panels were made using the developed composite face sheets with aluminium honeycomb core. The developed composite face sheets were tested for tensile and flexural conditions and the sandwich panels for edgewise and flatwise compression loads. Three samples for each of these tests were conducted in Shimadzu UTM with 50 kN capacity machine. A consistent load-displacement profile and the failure pattern were observed for all the samples tested in each test category. It is noted from these tests that the composite face sheets exhibited an ultimate tensile strength of 444 MPa and a flexural strength of 842 MPa which is pretty to close to the epoxy based composites used in the aerospace applications; sandwich panels showed an edgewise compressive strength of 610 MPa and flatwise compressive strength of 3.5 MPa. Tensile test coupons initially had undergone certain delamination before failure and failed close to the specimen holding end. Flexural test specimens were shown delamination of only one layer at the loading face. However, the specimen was well intact together even after failure. Bending mode of failure was noted during edgewise compression test of the sandwich; severe delamination was seen in the tension side of the sandwich whereas a line-folding crack with failure was exhibited at the mid-plane of the specimen. In case of flatwise compression, no evident of damage was observed in the sandwich structure. The second part of the paper describes the numerical simulations of these test cases including tensile, flexural, edgewise compression and flatwise compression using an explicit finite element solver viz. LS-DYNA. Material type 22 and 26 was selected to define the material behaviour of composites and honeycomb respectively. The delamination was modelled using *CONTACT_AUTOMATIC_SURFACE_SURFACE_TIEBREAK card with option 9 that works under B-K linear fracture mechanics law to define the normal and shear failure of cracks. The numerical results were found to match well with experimental observations for the individual coupons as well as the sandwich samples. Therefore, it is concluded from this study that the developed LS-DYNA simulation methodology can be used as a tool for composite sandwich panels based lightweight structural design. [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]

Piles are widely used in marine projects where inappropriate soils are present and soil replacement is not justified economically. Among various pile types, helical piles have been considered as a potential substitution for driven piles in offshore applications. The present paper investigates numerically the effects of tapered helices and inter-helix spaces to achieve the maximum compression capacity in homogeneous and in-homogeneous soil profiles. Both individual and cylindrical failure mechanisms were studied. Tapered helices with decreasing diameters from the top to bottom instead of the same number of identical helices were also studied. Results show that the best inter-helix spacing to helix diameter ratio is two to achieve the greatest pile capacity. Also, the compression load corresponding to 10% of the pile head settlement was found to be reasonable for computing the pile capacity. The results show that tapered helix piles offer better compression capacity than uniform helix piles with the same number of identical helices. In addition, tapered helix piles have almost similar load-settlement variation to solid frustum shape helix piles while in the latter more steel is consumed. In general, the present research highlights that using tapered helices due to their technical and economic performance is advantageous. [ABSTRACT FROM AUTHOR]

Although it is well known that the slamming-induced whipping can significantly increase the structural loading of ships, its consequence on the hull girder's collapse is still unclear. Moreover, the whipping-induced stresses are having a higher frequency than the wave-induced stresses. Hence some doubts are cast on the probability that the dynamic effects may provide additional strength reserves. This paper aims to investigate in a parametric way the dynamic ultimate strength of a stiffened panel, subjected to axial compression and lateral loads. The load amplitude curves for the axial stress are defined analytically by superimposing different components associated with several dominant load parameters, such as wave and whipping periods. In order to derive realistic loading scenarios, a broad range for each dominant load parameter is determined by analysing the hydro-elastic response of multiple container ships. The dynamic load factors are derived as the ratio between the dynamic capacity and the quasi-static one. Furthermore, it is shown that the dynamic effects are already existent in the wave loading scenarios, and this fact is attributable to some limitations of the Cowper–Symonds model. Thus the last section of this paper is dedicated to developing a new strain rate sensitivity model, which describes more accurately the strain rate sensitivity at low strain rates. [ABSTRACT FROM AUTHOR]

In this paper results on the evolution of Poisson's ratio under tensile and cyclic compression on low-density soft open-cell polyurethane foams (85, 63, 46 kg/m3) up to 80% of strain are presented as obtained by full-field deformation measurements. The Poisson's ratio was investigated using a Poisson's function and a tangent Poisson's function formulation, more capable to capture the instantaneous behavior of the foam and a possible auxetic behavior. The displacements' maps and the stress-strain curves obtained experimentally by digital image correlation are compared with the numerical results of the FEM analysis obtained for ν = 0 and ν ≠ 0. [ABSTRACT FROM AUTHOR]

The additional confinement loss caused by external loads has so far restricted the wide applications of photonic crystal fibers (PCFs). With the rapid development of metamaterials, there is an increasing interest in negative Poisson's ratio (NPR) composite structure due to its outstanding advances in energy and vibration absorption capabilities. In this paper, a novel design concept of PCF with NPR air holes composite structure is proposed. The feasibility of this novel PCF structure is verified by photo-elastic theory and finite element method under compression and impact loads to test the mechanical and optical properties of the fiber. The results show that the PCF with NPR air holes structure effectively suppresses the fiber deformation caused by external loads, thereby reducing the additional fiber confinement loss. Meanwhile, this novel concept displays structural diversity. The macro effective Poisson's ratio of the fiber can still be reduced by maintaining the generalized NPR holes cladding structure, which provides support for the flexible core layer design of PCF under different application requirements. In sum, this design concept subverts the traditional design method of photonic crystal fibers with complex structures and looks promising for future applications in optical fiber sensors. [ABSTRACT FROM AUTHOR]

This paper presents a series of novel hybrid columns incorporating emerging materials, being the alternative to pumpable standing supports used in underground mines. The infill material of these hybrid columns is the cementitious grout material while the exterior containers are either made of polyvinyl chloride (PVC), fibre-reinforced polymer (FRP) composite, geogrid or the combination of each two materials. To investigate the mechanical response of these columns under the uniaxial compression loading, the systematic laboratory tests covering eight large-scale tubular columns were conducted and the test results showed that: (1) the strain constant behaviour of PVC-confined cementitious grout (PCC) column is mainly attributed to the relatively low confinement after the yielding of the PVC tube; (2) the high strength-to-weight ratio and linear tensile behaviour of FRP leads to the stress-hardening behaviour of FRP-confined cementitious grout (FCC) column and the enhanced compressive behaviour of FCC is mainly related to FRP thickness; (3) both the FRP-PVC confined cementitious grout (FPCC) columns and FRP-geogrid confined cementitious grout (FGCC) columns exhibited the superior compressive behaviour either in terms of the large axial deformation or the load carrying capacity, compared with the unconfined cementitious grout material (UCM) under uniaxial compression loading. [ABSTRACT FROM AUTHOR]

In this paper, fatigue response under cyclic loading of a high-modulus asphalt mixture (EME14) is numerically investigated based on a coupling approach between damage mechanics and visco-elastoplasticity. The DBN (Di Benedetto-Neifar) model along, an isotropic damage, and a fatigue damage law are adopted to implement both visco-elastoplastic and damage constitutive equations. A set of laboratory experiments are conducted to calibrate the numerical model parameters. In the small deformation domain, complex modulus test results (complex modulus and viscosity) were experimentally fitted based on the 2S2P1D model. Direct tension parameters (stress levels in tension and in compression) were identified through the Di Benedetto viscoplastic criterion. Then, the experimental results of the fatigue test were interpreted to evaluate the damage amount associated with each cycle N and accordingly processed by the DGCB method, developed at the ENTPE (École Nationale des Travaux Publics de l'Etat), to eliminate parasitic effects commonly present in fatigue tests. Hence, a MATLAB program was implemented for uniaxial tension and compression load to estimate damage and fatigue modulus. The consistency between the numerical model outcomes and the experimental measurements showcased the capability of our coupling approach to accurately predict fatigue response under cyclic loading of a high-modulus asphalt mixture (EME14). [ABSTRACT FROM AUTHOR]

The aim of the paper was to develop a test database of the ultimate strength characteristics of full-scale steel stiffened plate structures under axial compressive loading at a temperature of −80°C. This paper is a sequel to the authors' articles (Paik et al. 2020a, and Paik et al. 2020b, ). In contrast to the earlier articles associated with room temperature or cryogenic condition, this paper investigated the effect of a low temperature at −80°C which is within the boundary range of temperature of the ductile-to-brittle fracture transition for carbon steels. A material model representing the test conditions was also proposed to capture the characteristics of carbon steels at low temperatures both in tension and in compression, and it was used in finite element method simulations of the full-scale experiment. A comparison between numerical analyses and experiments showed that the proposed model could successfully predict the failure modes and ultimate strength characteristics at low temperatures for stiffened plate structures under axial compressive loading conditions. [ABSTRACT FROM AUTHOR]

This paper reports on an investigation into the relationship between stiffness and applied force of an advanced biological composite structure using four techniques: experimental observation; finite element analysis (FEA); regression learner analysis; and, artificial neural networks (ANNs). The entire hydrated third metacarpal bones (MC3) from 16 thoroughbred horses were loaded in compression in an MTS machine. The stiffness was then determined from the applied force, MC3 displacement, and load exposure time. A variety of mathematical functions were fitted to the sample data points using MATLAB to demonstrate force-dependent stiffness. Two functions were found that exhibited a strong correlation between force and stiffness (R2 = 0.75). Additionally, a power function was found that demonstrated a stronger correlation between the stiffness and force (R2 = 0.81) if the exposure time was also incorporated. FEA considered the calculated force-dependent stiffness when assigning material properties. FEA results were compared with experimental data (for verification and validation), and a good agreement was found for the displacement (RMSE = 0.032 mm) and strain (RMSE = 61.85 με). Machine learning regression models were also employed to predict the stiffness of this complex structure. Applied force, exposure time, MC3 geometry (length and area of cross sections), and age were defined as the independent variables. The regression learner offered excellent reliability (R2 = 0.98) for the prediction of stiffness. Also, feedforward back-propagation artificial neural networks were employed to improve and generalize the stiffness prediction ability to a wider population. ANN regression analysis showed R = 0.992 for training, R = 0.99 for testing, and R = 0.991 for the all datasets. To confirm its accuracy, the ANN was used to predict stiffness of specific samples that were not used in its training. This offered excellent reliability in predicting real-world data that ANNs have not seen before (R = 0.976). [ABSTRACT FROM AUTHOR]

Timber structure is a mainstream form of ancient Chinese architecture. However, owing to factors such as weathering and long-time duration, most of the wooden structures have been damaged badly. Using iron hoops to enhance the original structures is the traditional method for pier reinforcement, which produces limited effects. In this paper, the new reinforcement materials carbon fibre-reinforced polymer used for strengthening short pier column have been studied. We designed nine timber columns, among which eight applied the carbon fibre-reinforced polymer for reinforcement. With the maximum bearing capacity of the hoop reinforcement columns increased by 20·7%, the research proved that hoop carbon fibre-reinforced polymer has reinforcement effect on axial compression columns. Finally, this paper analysed the short pier column strengthen by carbon fibre-reinforced polymer in theory and derived the calculation formula. In compression with test results from experiments and combining the theoretical analysis, the paper concludes the feasibility of using carbon fibre-reinforced polymer for timber structure reinforcement. [ABSTRACT FROM AUTHOR]

An approach to simulate the hysteresis loops of an unidirectionally SiC fiber-reinforced titanium matrix composite during tension-compression(T-C) fatigue loading has been developed in this paper. The T-C fatigue process of one cycle was divided into four stages of tension loading (TL), tension unloading (TU), compression loading (CL) and compression unloading (CU). It is assumed that fiber sliding relative to matrix occurs in the whole interfacial debonding area during TL. And there exists a closure stage of matrix crack during CL. Based on the BHE model, the stress–strain relationships during four stages have been derived. By combining the experimental normalized stiffness with the stress–strain relationship during TL, the average matrix crack spacing during various cycles are obtained. Combining the matrix cracking evolution law with another two damage evolution laws, the fatigue hysteresis loops of various cycles under T-C fatigue loading have been acquired. The theoretical results have been compared with experimental data of an unidirectionally SiC fiber-reinforced titanium matrix composite. And the effects of different damages on the hysteresis loops of TMCs have been investigated. [ABSTRACT FROM AUTHOR]

All explosions emit both thermal and blast energy. In recent years there have been several accidental explosive events that have emitted high thermal loads with the potential to cause thermo-mechanical damage to structures. Attempts to experimentally simulate these thermal loads and observe the response of structures to combined thermal and blast loads have not proven successful. This paper focuses on the design of, and results from a series of experimental trials investigating the response of steel columns to combined thermal loads from ceramic heating elements and long-duration blast loads within an Air Blast Tunnel (ABT). The combined effect of compressive loads from heavy-duty springs is also shown. The trials concluded that the ceramic heating elements were suitable to heat steel columns to levels initiating thermo-mechanical damage. Results from the tests showed an increased structural response in the columns subject to high thermal, compressive and blast loads compared to the isolated blast load. Numerical modelling of the columns is detailed and compared to trial results, providing validation for the computational methods. The experimental trials set a benchmark for future trials and provided results to validate the synergistic response of steel structures to combined blast and thermal loads from explosive events. [ABSTRACT FROM AUTHOR]

The increasing number of studies on the behaviour of stent placement in recent decades provides a clear understanding of peripheral artery disease (PAD). The severe mechanical loads (axial tension and compression, bending, radial compression and torsion) deformation of the femoropopliteal artery (FPA) is responsible for the highest failure rate of permanent nickel-titanium (Nitinol) stents. Therefore, the purpose of this article is to review research papers that examined the deformation of the natural load environment of FPA, the properties of Nitinol and mechanical considerations. In conclusion, a better understanding of mechanical behaviour for FPA Nitinol stents contributes to increased mechanical performance and fatigue-life. [ABSTRACT FROM AUTHOR]

Norms and guidelines on passive safety currently provide insufficient guidance on restoration, customisation or post-accident repair of vehicles. Vehicle rollover is usually considered to be one of the most complex cases. The analysis has shown very complex loads acting on the vehicle roof structure. Practice of vehicle post-accident servicing and design shows that the joint between roof structure and A-pillar is subjected to the most extreme damages. The paper pursues the aim of identifying rollover damages on roof structural elements and the influence of weld layout resulting from repair of vehicle roof A-pillar on the strength of safety frame during vehicle rollover. The methodology of strength test on vehicle roof support structure is presented in the body of the paper. Results generated during application of static compressive load to the vehicle roof structure are discussed in detail in the paper section dealing with the results. [ABSTRACT FROM AUTHOR]

The initiation and propagation of microcrack damage in concrete under compressive load have a great influence on structures that require high durability. This paper theoretically analyzed the nonlinear acoustic modulation mechanism in concrete at the initial stage of compressive cracking and explored the relationship between microcrack density and nonlinear response variation. Nonlinear behavior and microcrack development of concrete were simulated. The opening/closing state of microcracks under different cracking states and the propagation characteristics of nonlinear acoustic modulated signals were investigated. It was found that the change in microcrack density measured by the DI (damage index) of the nonlinear acoustic field technology was much more significant than that measured by DIC (digital image correlation). The experimental results showed the good feasibility of microcrack detection with width of 13–80 μm. Moreover, the experiment found that when the peak value of DI is between 0.02 and 0.2, microcracks occur in concrete. [ABSTRACT FROM AUTHOR]

This paper presents the geometry and material distribution influence on energy absorption systems and failure mode of glass epoxy tubes and carbon epoxy tubes in order to improve the structural performances. Experiments were carried out on different types of composite tubes subjected to axial compression load. After collecting the results of the crushing and drawing the load–displacement curve, the initial failure load, maximum crushing load and average load were found. From these parameters, the crashworthiness parameters were calculated. The comparison results between the parameters showed that the best structure of the glass epoxy tubes was the circular tube with eight layers, where produced the highest specific energy absorption at a value of 21.23 kJ/kg. [ABSTRACT FROM AUTHOR]

Most energy absorbing structures in automotive applications consist of metals. Those are characterised by high absolute energy absorption (EA) values yet low mass-specific energy absorption (SEAm). In contrast carbon fibre reinforced polymers (CFRP) reach higher SEAm values. The difference however is not a direct consequence of the density, weight specific stiffness or strength. Instead, the failure progression and hence the energy dissipation characteristics of metallic and CFRP structures are different. Whether a combination of the two material types leads to an increase or decrease of the SEA depends on the crash characteristics of the laminate which supposedly depends on the lay-up. The present paper reports on an experimental investigation on the crash behaviour of omega-shaped fibre-metal laminates (FML) composed of unidirectional CFRP prepreg layers and steel-foils under compressive axial loads. A potential of the tested hybrid laminates is proven by an increase of the mass-specific energy absorption value (SEAm) of 58%, compared to CFRP. [ABSTRACT FROM AUTHOR]

Plate buckling is a primary criterion for plated-structural design. In current structural design practice, the edges of plate elements are assumed to be simply supported. In reality, however, the plate edges are supported by longitudinal stiffeners and transverse frames, and thus there are some degrees of rotational restraints along the plate edges that are neither zero nor infinite but rather dependent on the torsional rigidity of the support members. The objective of this paper is to develop a method for implementing the rotational restraint effects into the plate buckling strength design. It aims to minimise the structural weight while maximising the plate buckling strength. In this paper, the buckling strength of plate elements subjected to compressive loads is calculated using design formulations. Examples are shown for the buckling strength design of steel plates in a Very Large Crude Carrier class tanker and a naval ship, demonstrating that the structural weight can be reduced by implementing the rotational restraint effects while meeting the plate buckling strength requirements associated with the structural safety design criteria. [ABSTRACT FROM AUTHOR]

In this paper, a new type of non-pneumatic tire is designed. The pneumatic parts of standard pneumatic tire are replaced by gradient anti-tetrachiral structure. Firstly, the in-plane mechanical properties and elastic limit load of anti-tetrachiral structures with different gradient factors are studied by experiment, finite element method and theory. Based on this, the structural design of non-pneumatic tire is carried out, and its mechanical properties under compression load are studied by finite element method. Results show that the gradient anti-tetrachiral structure and the non-pneumatic tire based on this structure have certain similarities in the deformation mode. The basic research of gradient anti-tetrachiral structure is of guiding significance to the design of non-pneumatic tire. It also shows that the non-pneumatic tire with the gradient anti-tetrachiral structure has good load-carrying capacity, and has a wide engineering application potential. [ABSTRACT FROM AUTHOR]

This paper studies the seismic performance of composite shear walls with concrete-filled square steel-tube boundary element and innovative shear connections. Eight specimens were investigated by reversed cyclic load tests. The test parameters were the type of the shear connections, the arrangement of a steel beam in the middle of wall body, the concrete strength and the axial compressive load ratio. The failure mode, hysteretic behaviour, ductility, stiffness and strength degradation, energy dissipation capacity and strains development were studied. The test results show that the hysteresis curves of the composite shear walls were plumper compared with traditional concrete shear walls. Composite shear walls with concrete-filled square steel-tube boundary element have good seismic performance. The strong shear connections had a considerable effect on the seismic performance of this composite shear walls. There was no considerable difference in the effect on seismic performance for the arrangement of a steel beam in the middle of wall body. Finally, the restoring force model for composite walls with concrete-filled square steel-tube boundary element was developed with adequate accuracy. [ABSTRACT FROM AUTHOR]

This paper deals with the experimental study devoted to cyclic compressive loading of three tropical species (Aucoumea Klaineana Pierre (AKP), Milicia Excelsa (ME) and Pterocarpus Soyauxii (PS)) at different moisture content (MC) levels. According to the French requirement, NF EN 408, 90 samples are taken from these three species. The experimental campaign consists of static tests concerning 15 samples and cyclic tests performed on 75 samples. First, the samples are loaded into the static compressive test until their collapse to obtain the mechanical characteristics of each species in terms of (i) the modulus of elasticity, (ii) the maximal strength and (iii) the stress at the yield point. Then, each sample is loaded five times in cyclic compressive loading, following the paths of loading-unloading-reloading, at different MC levels. The maximal load applied for each cycle corresponds to 10% of the collapse load of the AKP species. The results show a stiffening of the samples with the loading cycles. The stiffening is faster from the densest species to the least dense species. Besides, the phenomenon of densification, which occurs during the five loading cycles, is carried out with the constancy of compressive strength in the three species. [ABSTRACT FROM AUTHOR]

In the present paper, the effect of joint geometry and collar plate size is investigated on the structural behavior of the strengthened X-joints subjected to compression. In the first step, the developed finite element (FE) model is verified using experimental data of six collar plate strengthened and un-strengthened X-joints conducted in the present authors' previous study. After that, a total of 138 collar plate strengthened and un-strengthened FE models of tubular X-joints was conducted and analysed. Results show that the propagation of the plastic zone in strengthened connections with a big collar plate length is larger than the propagation of the plastic zone in strengthened connections with a small collar plate length. Finally, a theoretical equation is proposed based on the yield volume model to predict the ultimate capacity of X-connections strengthened with collar plates under brace compression. [ABSTRACT FROM AUTHOR]

This paper focuses on the elastic buckling strength of typical stiffened panels under bi-axial compression. Three levels of assumptions for stiffeners are investigated: (1) Vlasov assumption; (2) stiffeners’ web plate assumed deformable; (3) both stiffeners’ web and flange plates assumed deformable. The bi-axial buckling strengths for deck and bottom stiffened panels in typical merchant ships are obtained by minimum potential energy principle, and the results are compared with corresponding finite element analysis results. It shows that Vlasov assumption should be corrected, while the other two assumptions yield similar satisfactory results. Sensitivity analysis is made for scantlings of the stiffened panel. Above three assumptions all exhibit high efficiency. [ABSTRACT FROM PUBLISHER]

This paper describes compressive static load tests of concrete driven piles confined by Carbon Fibre Reinforced Polymer (CFRP). The tested piles include one concrete pipe pile and one concrete rectangular pile which are all partially confined by CFRP, and other two piles with the same dimensions without CFRP application. Tests program was performed to obtain the behaviours of these composite piles. Four Static Loading Tests (SLTs) were conducted and the results shown that those two types of composite pile demonstrate less vertical displacement with the same loading of traditional concrete piles. Furthermore, the traditional methods of Load-settlement (Q-s) curves, Settlement-lg (Load) (s-lgQ) curves and Settlement-lg (Time) curves are analysed. Due to un-plunging condition, the interpretation methods of Davisson's, DeBeers, Double-Tangent as well as Chin's methods are demonstrated for the ultimate bearing capacity of these four piles. It is concluded that the CFRP confinement increased the ultimate bearing capacity and this composite material can be perfectly applied in geotechnical condition. [ABSTRACT FROM AUTHOR]

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This paper outlines an experimental study on the static and dynamic compressive creep behaviour of structural silicone adhesively bonded joints. The silicone adhesives are subjected to dynamic compressive loading, which is a common case for structural façade and hybrid glazing system. Typical crack propagation of adhesives, relations between compressive load (stress) and displacement (creep strain) are examined experimentally. It is shown that the test specimen with adhesives featured by lower hardness and higher elongation at break exhibit notable crack distribution concentrated in the middle of the crack surface. The compressive behaviour consists of three regions as initial elastic, nonlinear transition and post linear, in which the latter has notable strength increase with the increase of compressive deformation. The secant compressive modulus are measured based on compressive stress and creep strain relations. It is demonstrated that the joint has higher secant compressive modulus due to less crack propagation. All test joints exhibit significant degradation of strength and energy absorption, which can be well fitted in similar exponential forms with normalized cycle numbers for test joints with different adhesives. [ABSTRACT FROM AUTHOR]

Sandwich structures with Miura-ori cores have been studied especially in aerospace industry. However, by removing the face sheets one can obtain esthetical, multifunctional, self-supporting structures for various applications, such as packaging. This study focuses on the mechanical performance of planar, self-supporting Miura-ori structures under compressive loads. Through systematic variations of both origami geometry and base material orientation, this study performs linear stress and stability analyses by utilizing the finite element method. The results reveal the effects of the geometric parameters and the material orthotropy on the structural performance, finally resulting in parameter ranges forming a basis for structural design. [ABSTRACT FROM AUTHOR]

Changes in Australian Masonry Standards and National Code of Construction for reinforced masonry (RM) under compression impress the need of a grout annulus and vertical bar confinement using 6 mm tie bars. Maintaining the verticality and centricity of reinforcement and restraining them with the tie bars is challenging and time consuming. BlockAid have designed masonry bar chairs to align and restrain the reinforcing bars central in the block cores. This paper presents an investigation to ascertain the performance of BlockAid bar chairs in supporting the reinforcing bars in the RM walls subject to vertical compression and out-of-plane loads. The mean compressive strength in the fully grouted RM walls with BlockAid bar chairs was determined equivalent to the control specimen which sustained maximum load of 3100kN, compared to 3030kN for the BlockAid sample. Strain in the vertical steel bars, with BlockAid bar chairs, remained compressive throughout the loading with no evidence of buckling. The out-of-plane test results of BlockAid walls were similar in terms of failure modes, load-displacement behaviour and steel strain variations. These observations conclude that BlockAid bar chairs are effective in restraining the vertical bars against buckling and do not compromise the compression and bending capacity of RM walls. [ABSTRACT FROM AUTHOR]

This paper presents experimental studies on the behaviour of a thin layer polymer mortared concrete masonry under combined shear–compression. Thirty thin layer mortared concrete masonry panels with five bed joint orientations were constructed and tested under vertical compression to generate a wide range of compression to shear ratios from zero to infinity at each of the bed joints of the panels. The strength and deformation characteristics are discussed in this paper. Unlike the conventional 10 mm thick cement mortared masonry, the thin layer polymer mortared masonry failed in a combined mechanism involving both the block and the mortar in some combination of shear–compression; however, similar to the conventional masonry, its strength and deformation were affected by the orientation of the bed joint to the direction of the applied loading. This paper reports a comparative study of the experimental results with a number of shear–compression tests on varied masonry systems reported in the literature; the thin layer mortared concrete masonry is shown trending towards isotropic behaviour compared to conventional masonry, which is distinctly orthotropic. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the bending behaviour of a reinforced concrete (RC) beam with different non-uniform frost damages. A multi-scale poromechanical approach is developed to build a bridge between the material deterioration process and the structural mechanical performance by considering the global heat and moisture transport and rebar confinement, as well as the local phase changes and poromechanical deformation. The real-time frost damage process is first simulated and experimentally validated for different depths of exposure on both the compression and tension sides and then used for testing the residual bending behaviour. The failure modes, load-carrying capacity and strain distribution of the reinforcement are fairly consistent with the experimental results. The bearing capacity decreases with the increment of the freeze-thaw cycles (FTC) and the frost exposure depth. Reinforcing bars can restrain not only crack propagation but also frost damage. Thus, the bearing capacity of the damaged beam on the compression side drops more than that on the tension side for the same exposure depth. Finally, an indirect method for the use of the equivalent deteriorated mechanical properties is compared with the detailed real-time simulation, and a simple design method is proposed for RC beams with partial frost damage. [ABSTRACT FROM AUTHOR]

Buckling and postbuckling behaviors of two models of sandwich plate reinforced by carbon nanotubes (CNTs) resting on elastic foundations and subjected to uniaxial compressive and thermomechanical loads are investigated in this paper. Material properties of all constituents are assumed to be temperature dependent and effective properties of CNT-reinforced composite layer are determined according to extended rule of mixture. Governing equations are established within the framework of first-order shear deformation theory taking into account von Kármán nonlinearity, initial geometrical imperfection, plate-foundation interaction and tangential elastic constraints of unloaded edges. Three types of loading are considered including uniaxial compression, preexisting thermal load combined with uniaxial compression and preexisting mechanical load combined with thermal load. Approximate analytical solutions are assumed to satisfy simply supported boundary conditions and the Galerkin method is used to derive nonlinear load-deflection relations from which buckling loads and postbuckling equilibrium paths are determined. The most important findings are that tangential constraints of unloaded edges significantly lowers buckling loads and postbuckling load capacity of sandwich plates and, in contrast, buckling loads and postbuckling strength are considerably enhanced as sandwich plate is constructed from CNT-reinforced composite core layer and homogeneous face sheets. [ABSTRACT FROM AUTHOR]

Geotechnical strata are often treated as horizontally homogeneous for hydromechanical analysis due to the vertical deposition of geological layers; however, such a treatment becomes no longer valid when vertical drilling or construction causes the localized disturbance of subsurface, which would result in radial heterogeneity of geomaterials. This paper presents a poroelastic solution for the saturated multilayered cylinder where multilayer is used to represent radial heterogeneity. After the application of Laplace transform, the governing equations in cylindrical coordinates are derived to obtain the stiffness matrix between stresses, displacements, and pore water pressure. The global matrix is assembled by the boundary conditions and the compatibility of interfaces between adjacent layers. Under time-dependent horizontal compression loads, a parametric study is performed for a cylinder comprised of two layers with distinct properties, and the results show that the load frequency and radial heterogeneity play a significant role in hydromechanical behavior of geomaterials: (1) the time-varying loading can induce a negative pore pressure, and the influence of cyclic loading with a high frequency is limited near the outer surface; (2) the radial heterogeneity due to permeability and compressibility affects the development of pore pressure. [ABSTRACT FROM AUTHOR]

Compressive load can directly influence the frost resistance and compressive strength degradation of concrete under freeze-thaw cycles. In this paper, the deterioration in the compressive strength of concrete under the both compressive load and freeze-thaw cycles was explored experimentally. Based on the experimental data, a predictive model of the deterioration process of concrete compressive strength under external load during freeze-thaw cycles was established. The comparison of the predicted results with reported experimental and in situ inspection results, revealed good agreement between our predicted results and those reported in the literature. It was concluded that based on the degradation model, an evolution model for the failure of the concrete surface under compressive load during freeze-thaw cycles was established. [ABSTRACT FROM AUTHOR]

The flow behavior and deformation mechanisms of the [001]-oriented single-crystal nickel-based superalloy PWA1483 are investigated under quasi-static compressive and tensile loading conditions at 750°C. We found that the tensile yield strength is larger as compared to the compressive strength, and the serrated flow only appears on the compressive stress–strain curves. Microstructural observations uncover that stacking fault shearing and microtwinning are prone to initiate in PWA1483 during tensile deformation, and the appearance of the Protevin–Le Châtelier effect in compression derives from the abrupt frequent bursts of the two mechanisms on a mesoscale, rather than the simple occurrence of these procedures. [ABSTRACT FROM AUTHOR]

In order to promote the research and development on evaluating the seismic performance of structures, China State Construction Engineering Corporation (CSCEC) planned to construct a large-scale loading testing facility, the Multi-Function Testing System (MFTS). This facility can perform full-scale, real-time, 6-degree-of-freedom static and dynamic testing of rubber bearings and many types of structural components including long columns, shear walls and cross shape joints. The basic performances of the MFTS are a clearance of 9.1 m × 6.6 m × 10 m for specimen installation, maximum x-directional displacement 1500 mm, maximum y-directional velocity 1570 mm/s and maximum z-directional compressive load 108 MN. The system configuration and performance specifications of the MFTS are presented in this paper. The inverse kinematics model and the nonlinear model of the hydraulic servosystem of the MFTS are built. A modified feedback forward kinematics algorithm is developed for real-time control of the MFTS. Internal force characteristics of the loading system are analyzed. The internal force control method based on real-time solution of basis of internal force space is proposed for the system with large motion ranges. The motion controller combining position control loop and internal force control loop is developed. To meet the requirement of simultaneously imposing vertical compressive load and horizontal displacement, a mixed load and displacement controller is designed, where a direct force control loop is used to improve the response speed of the force control and reduce spatial dynamic coupling effects. Finally, a dynamic bearing testing is performed. The test results demonstrate that the system using the proposed controller has good abilities on position tracking, force balance, and load following. [ABSTRACT FROM PUBLISHER]

This paper investigates the influence of heterogeneity on mechanical and acoustic emission (AE) behaviours of stratified rock specimens under uniaxial compression using a digital image processing (DIP)-based finite difference method (FDM). In the DIP, a developed image segmentation algorithm based on seeded region growing (SRG) is proposed to fully acquire the mesostructure of stratified rock specimens, instead of the traditional threshold value method. To sufficiently capture the heterogeneity of stratified rock, Weibull statistical manner is adopted to describe mechanical properties of each material component. Three schemes are adopted to study the effect of heterogeneity with different homogeneity index and different mesostructure under two compression loading conditions. The results show that heterogeneity has a great influence on the mechanical and AE behaviours of stratified rock. As the homogeneity of material components increases, the peak strength and brittleness of rocks increase, and the macro elastic modulus improves as well. Simultaneously, the AE modes change from swarm shock to main shock. Under the same component content, the macro-property is better while the component distribution is concentrative relatively, especially to the property of strength. For the coupling effect of mesostructure and heterogeneity arising from material components, mesostructure is considered to cause the visible increase of AE counts. And the numerical results agree well with the previously numerical results and experimental data. [ABSTRACT FROM AUTHOR]

Fatigue cracks were found at the diaphragm cutouts in the orthotropic steel deck (OSD) of a self-anchored suspension bridge while the in-service time of the bridge was less than 10 years. The causes of fatigue cracks of the diaphragm cutout are investigated in this study. The fatigue cracks initiated from the intersections of the arc curves and the straight lines, which form the geometrical discontinuity to the cutout edge. The in situ monitoring and finite element analysis under fatigue load model indicate that the cracking region in the cutout is in bidirectional compression. However, the thermal-structural analysis and tests show that the rib-to-diaphragm welding process produces high tension residual stress at the cracking points of the cutouts. The cutouts are under tension-compression cyclic loading because of the coupled stress, which is derived from the vehicle-induced stress and the welding residual stress. The results show that the strain energy method can present a reasonable fatigue life estimation for the diaphragm cutouts with full consideration of the residual stress. [ABSTRACT FROM AUTHOR]

Static compression is a well-known method to achieve very high pressures in ‘cold’ (degenerate) condensed matter. Because dynamic compression is adiabatic, it achieves both high pressures and temperatures, which are tunable by choice of pressure-pulse shape. Dynamic compression uses supersonic hydrodynamic variables, which are straight forward to measure, to achieve a wide range of extreme thermodynamic states in degenerate condensed matter. Because dynamic compression developed primarily in national laboratories, it is relatively unknown to a significant portion of the high pressure community. This paper is a brief review of (i) dynamic compression itself, (ii) its application to making metallic fluid H (MFH) and (iii) implications of data generated at extreme conditions with dynamic compression for understanding the unusual magnetic fields of Uranus and Neptune, which are made primarily by convection of semiconducting and MFH. Metallic hydrogen made under dynamic and static compression is compared. [ABSTRACT FROM PUBLISHER]