Axial Compressive Load Research Articles

Cross-sectional mechanical characteristics and sensitivity analysis of unbonded flexible risers under axial loads

Unbonded flexible risers exhibit complex structures. Different structural layers can withstand axial loads and exhibit different degrees of coupled deformation. Based on the different material properties and structural forms of each layer of an unbonded flexible riser, the structural layers are divided into three types: cylindrical, steel helical, and polymer helical layers. This study establishes a theoretical model of flexible risers under axial loads based on the law of conservation of energy and the geometry of deformation, and deduces theoretical expressions for the axial load and axial stiffness of flexible risers. MATLAB was used to compile calculation programs to calculate the cross-sectional mechanical properties of flexible risers under axial tensile and compressive loads and to compare the calculation results with the experimental results and the results of other researchers to verify the reliability of the theoretical derivation and calculation programs. By further calculating the cross-sectional force distribution of each structural layer of the flexible risers under axial tensile loads, it is clarified that the tensile armor layer is the main component that can withstand axial tensile loads. A sensitivity analysis of the helix angle and number of helical strips of the tensile armor layer on the tensile properties of flexible risers was conducted; the results show that the helix angle had a more obvious influence on the tensile properties of flexible risers. The results of this study can provide a reference for the structural design and optimization of flexible risers.

Behaviour of polymer-filled–concrete–steel double-skin tubular columns under combined lateral impact and axial compression loading

The paper presents a study on the suitability of using a Polymer as a protective layer for critical structural elements prone to impact damage. Conventional damage mitigation methods include using an outer steel jacket with a void, protecting the inner concrete-steel composite column. Whilst it is usually found that the outer steel jacket can partially negate the impact load, the inner column still experiences a significant brunt of the impact load. In order to minimise the damage to the overall critical structural element, a concept of a Polyurethane Polymer-Filled–Concrete–Steel Double-Skin Tubular Column is proposed. Scaled-down versions of two polymer-filled double-skin column configurations were tested under low-velocity impact using a drop tower. The pre and post-damage columns were tested for their axial capacities. These polymer-filled columns were critically compared to their nominal samples without the Polyurethane fill. It was shown that the mid-span deflection and localised indentations were reduced by 17%, and the localised deformations (at the point of impact) were reduced by up to 70% overall. The columns with Polyurethane also showcased retention of 70% of axial capacity post-impact, whilst the nominal sample was only capable of retaining 48%. Finally, the intrinsic properties of Polyurethane were discussed along with a critical discussion on its ability and mechanism on how energy is dissipated by comparing mechanical and chemical properties.

Effects of Kerr-type viscoelastic coupling layer with different stiffnesses on stochastic stability of Rayleigh double beams

This paper discusses the stochastic stability of a double Rayleigh beam system connected by a Kerr-type three-parameter elastic layer with two different stiffnesses, under compressive axial loads. The beams are modeled using the Rayleigh beam theory, and the axial forces consist of a constant component and a time-dependent stochastic function. The study investigates the almost-sure and moment stability of the double beam system subjected to stochastic compressive axial loading, utilizing the Lyapunov exponent and moment Lyapunov exponents. In the case of weak noise excitations, a singular perturbation method is employed to derive second-order expansions of the moment Lyapunov exponent and the Lyapunov exponent. Monte Carlo simulation is included to validate the obtained results. A numerical study is conducted for selected parameters, and the almost-sure and moment stability in the first and second perturbation are graphically presented. The results provide insights into the influences of different stiffnesses, damping, and the shear parameter of the Kerr-type layer on the stochastic stability of the coupled Rayleigh beam mechanical system, considering the effects of rotational inertia. It is quantitatively and qualitatively determined that reducing the stiffness of one part of the Kerr-type layer leads to a decrease in the stable region of stochastic stability, while reducing the shear parameter results in an increase in the stable region of stochastic stability. Furthermore, a quantitative relationship between different dampings of the Kerr-type viscoelastic layer is determined, where increasing either of the two damping parameters leads to an expansion of the stable region of stochastic stability. The inclusion of rotational inertia effects through the Rayleigh beam theory contributes to more accurate approximations of the obtained solutions.

Stiffened Hollow Structural Section Joints in Fire

This research examines the ability of stiffened Hollow Structural joints to withstand elevated temperatures when subjected to axial compressive loads on the brace. Extensive numerical simulations were conducted to assess the impact of geometrical factors in the main members and reinforcing plate on the fire resistance of SHS T-joints. The accuracy of the numerical models was verified by comparing them to existing test results. The findings demonstrate that the use of stiffener significantly enhances the ability of SHS T-joints to withstand elevated temperatures. The fire resistance of the reinforced joints primarily relied on the brace-to-chord width ratio and the reinforcing plate thickness to chord wall thickness ratio. However, increasing the reinforcing plate thickness beyond 1.5 times the chord wall thickness did not yield any beneficial effects on fire resistance. Additionally, factors such as half-width to thickness ratio of the chord, reinforcing length, and reinforcing type had negligible effects as long as they adhered to the required limit values based on Eurocode 3 EN 1993-1-8.

Effects of structural size and confinement on CFST column plastic hinge length

The objectives of this work are to study the influence of structural size on the plastic hinge length of square concrete-filled steel tubular (CFST) columns and to discover the influence of confinement generated by steel tubes on the plastic hinge length. A total of 24 square CFST columns were designed and tested with different column widths (i.e., 200 mm ∼ 800 mm) and different confinement effects (described by width-to-thickness ratio, i.e., 50, 80 and 100). The failure behavior and the curvature distributions of the tested columns subjected to axial compression loads and horizontal cycling loads were reported, and the corresponding plastic hinge lengths of the columns were obtained. The test results indicate that, as the column width increases, the plastic hinge length increases linearly, about 0.6– 0.9 times the column cross-sectional widths. Also, as the confinement effect increases, namely, the magnitude of the width-to-thickness ratio decreases, the plastic hinge length decreases slightly. Moreover, the non-dimensional plastic hinge length, defined as the ratio of plastic hinge length and column width, was proposed. The non-dimensional plastic hinge length decreases with increasing the column width, showing a significant size effect. An empirical formula for predicting the magnitude of the plastic hinge length of CFST columns was established.

Structural Performance of Strengthening of High-Performance Geopolymer Concrete Columns Utilizing Different Confinement Materials: Experimental and Numerical Study

The objective of this study was to investigate the effectiveness of different confinement materials in strengthening geopolymer concrete (GP) columns subjected to axial compression loading. This research encompassed both experimental and numerical analyses. The experimental phase involved testing seven circular GP columns, while the numerical phase involved developing 3D finite element (FE) models using ABAQUS software. The primary focus of this study was to assess the impact of using outer and inner steel tubes, as well as an outer polyvinyl chloride (PVC) tube and a carbon-fiber-reinforced polymer (CFRP) sheet. To validate the FE models, the experimental results were utilized for comparison. The findings of this study revealed that the outer steel tube provided superior confinement effects on the GP column’s concrete core compared to the PVC tube and CFRP sheet. The axial capacities of the columns confined with steel, PVC, and CFRP materials were observed to increase by 254.7%, 43.2%, and 186%, respectively, in comparison to the control specimens. Furthermore, the utilization of all confinement materials significantly enhanced the absorbed energy and ductility of the columns. The FE models demonstrated a reasonably close match to the experimental results in terms of load–displacement curves and deformation patterns. This correspondence between the numerical predictions and experimental data confirmed the reliability of the FE models and their suitability for generating further predictions. In summary, this study contributes to the field by exploring the efficacy of various confinement materials in strengthening GP columns. The results highlight the superior performance of the outer steel tube and demonstrate the positive influence of PVC and CFRP materials on enhancing the structural behavior of the columns. The validation of the FE models further supports their reliability and their potential for future predictions in similar scenarios.

Reducing Effects of Initial Imperfection by Investment in the Orthotropic Characteristics of Laminated Composite Plate

The target of this study is to reduce the impact of initial imperfection on the nonlinear dynamical performance of laminated composite plates by taking advantage of the orthotropic characteristics of laminated composite plates by changing carbon fiber sawing in the mass matrix and fiber orientation with different patterns and studying the effect of this optimization without and with initial imperfection (Wo) and different aspect ratios (W/L) and various boundary conditions through analyzing the load-displacement responses for plates under axial in-plane compressive loads by using the FORTRAN 94 programming language. Von-Karman's assumptions are utilized to include geometric nonlinearity for nine node isoperimetric quadrilateral components with five degrees of freedom into the structural model, which is based on first-order shear deformation theory. The Newmark’s implicit time integration method and Newton-Raphson iteration concurrently are employed to solve the nonlinear governing equation in conjunction. The study proved the effectiveness of the carbon fiber's varying geometric distribution and the difference in its directions in reducing the negative effects of the initial imperfection on the large elastic-plastic displacement and critical buckling. To highlight the veracity of the results, some of them have been validated against those found in the literature review. Doi: 10.28991/CEJ-2023-09-07-03 Full Text: PDF

Test on Compressive Performance of Hollow Concrete-Filled Sandwich Circular Steel Tubes Connected by Thread

The connection method of lengthening the steel tube of hollow concrete-filled sandwich circular steel tubes and threaded connections is proposed. The length, depth and position are the basic parameters. Twelve hollow concrete sandwich circular steel pipes with threaded connections were designed and subjected to axial compression tests. The axial compressive loading–longitudinal compressive displacement curves, axial compressive loading strain of steel tube curves and failure mode of the specimens are analyzed, and the effects of different parameters on the axial compressive-bearing capacity and stiffness of the specimens are studied. The results showed that within the range of parameters studied, the axial compression load–longitudinal compression displacement curves of the specimens were the linear elastic stage and the elastic–plastic stage, which can be divided into a yield-strengthening stage and a decreasing stage. The bearing capacity and strength of the lined threaded connection specimen are not inferior to those of the ordinary specimen or the welded specimen. The bearing capacity and strength of the specimen increase with the increase of the thread length. The bearing capacity and strength of the specimens connected with inner liner screws at the ends are higher than those connected with inner liner bolts at the middle.

Biomechanical analysis of tibial plateau posterolateral fracture fragment fixation and introduction of a lateral tibia plateau hook plate system

BackgroundFixing the posterolateral fragments of tibial plateau fractures has been challenging owing to potential neurovascular injuries and fibular head blocks. Several surgical approaches and fixation techniques have been reported, with distinct limitations. We propose a novel lateral tibia plateau hook plate system and compare its biomechanical stability with other fixation methods. MethodsTwenty-four synthetic tibia models were simulated to present posterolateral tibial plateau fractures. These models were randomly assigned to three groups. Group A models were fixed with the lateral tibia plateau hook plate system, Group B with variable-angle anterolateral locking compression plates, and Group C with direct posterior buttress plates. The models’ biomechanical stability was evaluated using static (gradually increased axial compressive loads) and fatigue (cyclically loaded from 100 to 600 N for 2000 cycles each) tests. ResultsGroups A and C models exhibited comparable axial stiffness, subsidence load, failure load, and displacement in the static test. Group A model exhibited higher subsidence and failure loads than Group B model. Groups A and C models exhibited comparable displacement at 100 N cyclic loading in the fatigue test. Group C model was more stable at higher loads. Group C model endured the highest subsidence cycle numbers, followed by Groups A and B models. ConclusionsThe lateral tibia plateau hook plate system provided similar static biomechanical stability as the direct posterior buttress plates and comparable dynamic stability under limited axial loading. This system is a potential posterolateral treatment choice owing to its convenience and safety, in treating tibia plateau fractures.

Experimental examination of the axial compression conduct of filament-wound cylindrical composite tubes at different wall thicknesses and orientation angles

This study presents the results of experimental research on the behavior and stretching of hollow cylindrical epoxy tubes made of glass, carbon, and kevlar fibers subjected to axial compression load. Hollow cylindrical tubes were fabricated by fiber winding method using glass, carbon, and kevlar fiber-reinforced composite materials. In this study, hollow cylindrical composite tubes with constant outer (Ø17 millimeters), two different inner diameters (Ø12 and Ø13 millimeters; 2 ve 2,5 millimeters wall thickness), and 80 millimeters in height. Experimental research was carried out for two dissimilar wall thicknesses and four fiber orientation angles. The compressive strengths of all samples were investigated experimentally by applying loads in the axial direction. Twenty-four configurations of composite specimens were fabricated (three reinforcement materials, four winding angles, and two wall thicknesses) to research the impact of axial compression stress. Experimental results revealed that polymer reinforcement material, fiber winding angle, and wall thickness have a significant impact on the compressive stress of cylindrical composite tubes as a result of applied load in the axial direction. The conclusions show that the compressive stress of all reinforcement rises as the orientation angle and wall thickness increase under an axial compression load, and the compressive stress reaches a maximum when the orientation angle is 90° under an axial compression load. It was observed that the axial compressive stress was highest in glass/epoxy samples with 217 MPa, followed by carbon/epoxy samples with 173 MPa and kevlar/epoxy samples with 145 MPa, respectively. The axial compressive stress of all samples was highest at a 90° orientation angle and lowest at a 15° orientation angle. were found to have low values. It was observed that the axial compressive stress value increased in all reinforcement materials as the wall thickness increased.
 *CRITICAL: Do Not Use Symbols, Special Characters, Footnotes, or Math in Paper Title or Abstract.

Performance analysis and optimization of square tubes with different shapes, sizes, and patterns of holes under axial compression loading

Tubular structures are common in vehicles in the form of crash energy absorbers. Inevitably, these tubes contain holes for assembling fasteners and heating sources. Though the introduction of holes in the surface of the tube minimizes the initial peak crushing force (IPF), their structural stability also gets affected, which leads to a reduction in energy absorption capacity (EA). Therefore, the shape, dimension, and patterns of the holes in the tubular structure are to be scrutinized to minimize its unstable response during the crash event. This paper addresses the hole’s position, shape, and dimensional effects on the performance characteristics of aluminum square tubes subjected to axial quasi-static compression experimentally. Numerical models were initially created using ABAQUS/CAE® code for simulating the quasi-static structural response of square tubes (without holes) and validated against experiments. Further, numerical analysis was explored to investigate the hole’s position, shape, and dimensional effects on IPF and EA. The performance characteristics of all the examined specimens were quantified based on the best performance with the help of the TOPSIS method. Finally, Response Surface Methodology (RSM) was carried out to determine the best optimal square tube with holes. It was observed that, with an increase in the hole size, the IPF gets minimized. Among all the specimens, the diamond-shaped hole exhibits the best performance characteristics. The study also reveals that the EA varied greatly with the arrangement of holes (patterns). The research findings can provide ample guidance when designing crash tubes in the automotive protective system.

Experimental residual capacity of steel-reinforced concrete-filled steel tubular stub columns after fire exposure

Technological advances in the development of steel–concrete composite structures have led to the introduction of novel types of sections in the sought of higher load-bearing capacities. Particularly for composite columns, the axial capacity of concrete-filled steel tubular (CFST) sections may be enhanced by the introduction of an open steel profile embedded within the concrete infill, forming the so-called steel-reinforced concrete-filled steel tubular (SR-CFST) columns. An important aspect that should be revised, in order to safely use these sections in design, is their performance after a fire. In this experimental program, six SR-CFST stub columns are tested in the post-fire situation. Two series of columns comprising three circular and three square sections with the same steel usage are tested for comparison purposes. The size of the inner steel profile is varied in order to investigate its effect over the post-fire capacity of the columns. The specimens were initially exposed to elevated temperatures inside an electric furnace, and then cooled to ambient temperature; afterwards compressive axial load was applied gradually until failure, to ascertain their residual capacity. The experimental results show the high ductility of the SR-CFST stub columns after heating, with the circular specimens reaching higher post-fire peak loads than their square counterparts. This load increases with the size of the embedded steel profile. The post-fire capacities of the columns are evaluated through the Residual Strength Index, showing similar values for both circular and square SR-CFST columns. Finally, a design equation is proposed to facilitate the evaluation of the post-fire compression resistance of SR-CFST columns, as an extension of the existing room temperature design equation in Eurocode 4 Part 1–2 for CFST columns, accounting for the degradation of the steel and concrete after fire exposure through the corresponding residual factors.

Testing on global stability performance of multi-celled CFST walls with three simply-supported edges

Multi-celled concrete-filled steel tubular wall (MCFSTW) is a composite structural system. In engineering practice, MCFSTWs are always orthogonally arranged to form wall limbs with different section forms. For slender wall limbs, their global stability is widely concerned and deserves further investigation. To evaluate their global stability performance, the single wall limb isolated from the whole wall limb is commonly regarded as a wall member with lateral edges constrained by simple supports. In this study, experimental and numerical studies were conducted to predict the global stability resistance of MCFSTWs with three simply-supported edges. Firstly, three specimens were tested under axial compressive load. Based on the test results, the failure modes were discussed and summarized. Secondly, a refined FE model considering boundary constraints and deformations was developed. According to the orthotropic plate theory, the theoretical formula of the elastic buckling load for MCFSTW with three simply-supported edges was derived and validated. Then, the existing stability curves were verified by comparing them with numerical results. The results indicated that they are not adequately accurate for practical engineering applications. Finally, a stability curve was proposed by fitting the FE points and validated against the modified test points, indicating that the proposed curve is capable of predicting the global stability resistance of MCFSTWs with three simply-supported edges.

Numerical analysis and design of cold-formed high strength steel RHS X-joints at elevated temperatures

A numerical program is carried out in this study with an aim to investigate the static performance of cold-formed high strength steel (CFHSS) X-joints with square and rectangular hollow section (SHS and RHS) braces and chords at elevated temperatures. The numerical investigation was performed through the finite element (FE) method using mechanical properties at elevated temperatures. The FE models developed and validated by the authors for identical CFHSS X-joints at room temperature and post-fire conditions were used in this study to perform numerical investigation at elevated temperatures. The SHS and RHS X-joints were subjected to axial compression loads through brace members. The validated FE models were used to perform a comprehensive FE parametric study at 400°C, 500°C, 600°C and 1000°C that comprised in total 756 FE specimens. Using mechanical properties at elevated temperatures, nominal resistances were predicted from design rules given in European code and Comité International pour le Développement et l'Etude de la Construction Tubulaire (CIDECT) and compared with the residual strengths of the investigated X-joints. Overall, SHS and RHS X-joint specimens were failed by chord face failure, chord side wall failure and a combination of these two failure modes. Generally, predictions from design rules given in European code and CIDECT are quite conservative but scattered and unreliable. Therefore, economical and reliable design equations are proposed in this study for predicting the resistances of cold-formed steel RHS X-joints made of S900 steel grade at elevated temperatures.

A method to evaluate the axial buckling load of periodic Vierendeel beams

This paper presents some closed form solutions for the buckling problem of periodic Vierendeel girders subjected to compressive axial loads. These are obtained by studying a geometrically non-linear ideal discrete beam, composed of cells or panels that deform only according to the inner forces transferring modes of the girder unit cell. In particular, the recursive equations governing the equilibrium of this discrete system are derived by the virtual works principle. Then, they are exactly solved and formulae for the critical loads are achieved. Although the ideal girder deforms with geometrically not compatible longitudinal shear strains, it gives very accurate predictions in a wide range of conditions of technical interest. These theoretical results are used as starting point for the analysis of the stiffening effect yielding a Euler critical load significantly higher than the buckling load evaluated on the basis of the classical Engesser’s assumptions. Specifically, by an ideal girder auxiliary solution, the discrete systems of self-equilibrated inner bending moments (self-moments) restoring the longitudinal shear strains compatibility are studied and it is shown that the axial loads under which these moments exist are accurate critical loads estimates of the real girder. Closed form solutions are obtained also for this problem and a simplified formula is derived for evaluating real girders buckling loads. The applicability of the reported solutions is verified by a validation study based on a series of finite element girder models.

Experimental investigation of AAC masonry walls reinforced with steel wire mesh embedded in bed and bed-head joint under axial compressive loading

Masonry buildings are the most common building type in Northeast India. For the last 4–5 years, low strength Autoclaved Aerated Concrete (AAC) blocks have been widely used in most new construction. Masonry buildings are fragile and sustain significant damage when subjected to seismic excitation due to their low tensile strength and lack of earthquake-resistant features. Steel wire mesh is a low-cost, readily available material that is commonly adopted to strengthened unreinforced masonry by wrapping the entire surface of the wall. However, it is very un-economical in large scale construction. Embedding steel wire mesh to the bed and bed-head joint mortar of low-strength masonry units, such as AAC, has received little attention and possibly act as an earthquake-resistant feature in masonry buildings. The present study attempts to investigate the compression behaviour of AAC masonry walls when embedding three different types of steel wire mesh. The steel wire mesh was embedded using two methods, i.e., embedding steel wire into the masonry bed joint and the masonry bed-head joint. Three strengthening configurations were adopted for both the method and all three types of steel wire mesh, i.e., (−) straight configuration, L configuration, and Z configuration. The test result indicated that the inclusion of steel wire mesh in the masonry bed joint and bed-head joint enhanced the failure patterns, axial load-carrying capacity, stiffness, ductility, and energy dissipation for both strengthening methods, with bed-head joint specimens outperforming bed-joint and URM masonry.

Optimal design of composite cylindrical shells subject to compression buckling strength

PurposeThe objective of the present work is to present the design optimization of composite cylindrical shell subjected to an axial compressive load and lateral pressure.Design/methodology/approachA novel optimization method is developed to predict the optimal fiber orientation in composite cylindrical shell. The optimization is carried out by coupling analytical and finite element (FE) results with a genetic algorithm (GA)-based optimization scheme developed in MATLAB. Linear eigenvalue were performed to evaluate the buckling behaviour of composite cylinders. In analytical part, besides the buckling analysis, Tsai-Wu failure criteria are employed to analyse the failure of the composite structure.FindingsThe optimal result obtained through this study is compared with traditionally used laminates with 0, 90, ±45 orientation. The results suggest that the application of this novel optimization algorithm leads to an increase of 94% in buckling strength.Originality/valueThe proposed optimal fiber orientation can provide a practical and efficient way for the designers to evaluate the buckling pressure of the composite shells in the design stage.

Axial Compressive Behavior of Cross-Shaped CFST Stub Columns with Steel Bar Truss Stiffening.

Concrete-filled steel tube (CFST) columns have been widely used in residential buildings due to their high bearing capacity, good ductility, and reliable seismic performance. However, conventional circular, square, or rectangular CFST columns may protrude from the adjacent walls, resulting in inconvenience in terms of the arrangement of furniture in a room. In order to solve the problem, special-shaped CFST columns, such as cross-shaped, L-shaped, and T-shaped columns, have been suggested and adopted in engineering practice. These special-shaped CFST columns have limbs with the same width as the adjacent walls. However, compared with conventional CFST columns, the special-shaped steel tube provides weaker confinement to the infilled concrete under axial compressive load, especially at concave corners. The parting at concave corners is the key factor affecting the bearing capacity and ductility of the members. Therefore, a cross-shaped CFST column with steel bar truss stiffening is suggested. In this paper, 12 cross-shaped CFST stub columns were designed and tested under axial compression loading. The effects of steel bar truss node spacing and column-steel ratio on the failure mode, bearing capacity, and ductility were discussed in detail. The results indicate that the columns with steel bar truss stiffening can change the final deformation mode of the steel plate from single-wave buckling to multiple-wave buckling, and the failure modes of columns also subsequently change from single-section concrete crushing failure to multiple-section concrete crushing failure. The steel bar truss stiffening shows no obvious effect on the axial bearing capacity of the member but significantly improves the ductility. The columns with a steel bar truss node spacing of 140 mm can only increase the bearing capacity by 6.8% while nearly doubling the ductility coefficient from 2.31 to 4.40. The experimental results are compared with those of six design codes worldwide. The results show that the Eurocode 4 (2004) and the Chinese code CECS159-2018 can be safely used to predict the axial bearing capacity of cross-shaped CFST stub columns with steel bar truss stiffening.

The Performance of Isolated Half-Scissor Like Elements Mechanism Under Compression Axial Load

Half-Scissor Like Elements (H-SLEs) deployable mechanism is the prefab scissor based structural mechanism consists of two bars with bolted connection to enable structure change shape. An experimental investigation on the isolated H-SLEs deployable mechanism under compression axial load was presented. A total of twelve specimens were fabricated in two series with six specimens each series were tested on their strength and stability at deployed configuration. The test specimens in series 1 mm thick C75 section were namely S1, S2, S3, S4, S5 and S6 while series 0.75 mm thick C 75 section were namely S7, S8, S9, S10, S11 and S12. The test specimens consist of C 75 and C 100 section which connected with M6, M8 and M10 bolt in grade 8.8. The compression axial load was applied at the center of 3 mm thick loading platform. The experimental results obtained indicated that four types of failure modes observed, i.e. bolt bending failure, section bearing failure, member buckling failure and instability due to horizontal displacement at mid-height of H-SLEs deployable mechanism (Bolted joint area). Among these failure modes, bolt bending failure was dominated the overall structure stability and impacts others failure modes indirectly while section thickness has impacted the buckling and bearing failure. The ultimate load capacity over BS EN 1993 design bearing resistance ratio obtained for M10 bolt was satisfactory. Besides, twisted effect observed during load applied also contributed to the failure modes identified. Thus, the H-SLEs deployable mechanism with stiffener with M10 bolt connection is necessary for future research in the application of spatial deployable structure purposes.

Experimental and theoretical study on an innovative energy absorption structure comprised of composite materials with necked‐down section subject to axial compressive load

AbstractEnergy absorption structure with necked‐down section possesses great application prospect owing to superior energy absorption ability. However, rare studies on this innovation structures were conducted. Therefore, an innovative energy absorption structure which consists of a composite tube and a trigger structure was proposed. In the trigger structure, necked‐down section is included. To investigate effect of thickness of composite tube, diameter variation and angle variation of the necked‐down section on energy absorption performance, 56 kinds of parameter configuration were generated, each of which was repeatedly tested three times. From the results of comprehensive experimental study, it can be concluded there were five different energy dissipation patterns for the proposed energy absorption structure. Different energy dissipation patterns were related to different failure modes. Brittle failure was featured by energy dissipation pattern I and II at stable energy dissipation stage while energy dissipation pattern III and IV played important role in progressive failure. Compared to the brittle failure mode, the SEA and force fluctuation ratio of the progressive failure mode increased and decreased by 48% and 52%, respectively. Energy absorption ability can be described by average compressive load capacity at stable energy dissipation stage, for which the theoretical model was developed. Effectiveness of proposed theoretical model was validated by comparing predicted average compressive load capacity with that obtained from experiment.