Quasi-static Axial Compressive Loading Research Articles

Performance of tri-tubular conical energy absorber under axial compression

Quasi static axial compression loading on tri-tubular cone (TC) has been carried out using LS-DYNA finite element analysis method. Tri-tubular cones of three arrangements; the first arrangement (model TC-1) consists of cone heights of 50 mm, 75 mm and 100 mm where the inner cone is the maximum height. The second arrangement (model TC-2) consists of cone heights of 100 mm, 75 mm, and 50 mm where the outer cone is the maximum height. The third arrangement (model TC-3) consists of three cones of the same height of 100 mm. Cone semi vertex angle of 20o was maintained for all tri-tubular cones tested. Materials used for this research are glass, jute and jute-glass/epoxy. Crashworthiness analyses were performed to investigate the effect of material used, and tri-tubular cone arrangement on peak load. Crush efficiency, and absorbed energy were drawn and discussed. Failure mechanism of the fractured specimens was also discussed. Effect of number of layers and fiber stacking sequence were also investigated. Results show that the cone arrangement TC-3 gives better performance than the cone arrangement TC-2 followed by the cone arrangement TC-1. Maximum load obtained by tri-tubular cone type TC-3 was found higher 7.09% and 14.96% than TC-2 and TC-1 respectively for glass/epoxy. Material saving was achieved by using tri-tubular cones of different heights under compression. Material used has significant influence on the absorbed energy. Failure mode of tri-tubular conical energy absorber was presented and discussed.

Crashworthiness performance of filament wound GFRP composite pipes depending on winding angle and number of layers

The main goal of this study is to enhance the crashworthiness performance of tubular composites to absorb more energy by optimizing the winding angle of their fibers. The crashworthiness performance of glass fiber-reinforced polymer composite pipes manufactured using the filament winding is investigated in detail. The effects of the winding angle of the fibers and thickness of the tube wall on the energy absorption were examined through quasi-static compression tests. The composite pipes were produced with 1200 tex E-glass fibers and Epikote 828 resin as the matrix material. The winding angles of ± 30°, ± 45°, ± 55°, ± 75°, and ± 90° were evaluated, and the number of the winding layers, ranged from 1 to 3, was also assessed. Quasi-static axial compressive loading was applied to 15 specimens using a hydraulic actuator. The results revealed that the one-layer specimens experienced buckling damage at low load levels, while an increase in the number of the layers led to higher load-carrying capacity and different types of damages. Furthermore, as the number of the layers increased, the load-carrying capacity and energy absorption of the specimens significantly improved. Progressive failure was observed in the specimens [± 90] for all the layers' configurations, with the specimen [± 90]3, having three layers, exhibiting the highest performance in terms of the load-carrying capacity and energy absorption. The failure modes indicated a combination of the fibers' separation, buckling, diagonal shear failure, and crushing in the upper and lower heads.

Energy absorption of diamond lattice cylindrical shells under axial compression loading

A mapping method was proposed to construct the lattice cylindrical shell (LCS) based on the triply periodic minimal surfaces (TPMS). The diamond lattice cylindrical shell (D-LCS) was designed using the proposed method and fabricated by selective laser melting (SLM). The experimental tests were conducted to investigate the energy absorption performance of these structures under quasi-static axial compression loading. The finite element (FE) models were established and validated using experimental results. Furthermore, the influence of the design parameters on the deformation modes and energy absorption performances of the D-LCSs were studied by parametric studies. The results showed that the D-LCS exhibited superior energy absorption performances compared with its counterparts. The relative density, cell size, radial variation coefficient, and mapping angle had significant effects on the deformed modes and energy absorption performances of the D-LCS structures. The findings of this study were expected to facilitate the design of the D-LCS structures for energy absorption applications.

Energy absorption investigation of octagonal multi-layered origami thin-walled tubes under quasi-static axial loading

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.

Effect of layering layout on the energy absorbance of bamboo-inspired tubular composites

Gradient distribution of vascular structure made the bamboo wall structure so effective which improved the load-bearing capacity of such bio-mimicked energy absorption structures and modify the crush behavior of thin-walled composite tubes. In this research, the influence of the layering design and stacking sequence on the crush behavior, failure mechanism and absorbed energy of bamboo-inspired GFRP composite tubes is assessed experimentally and numerically. Quasi-static compression tests were conducted to explore seven permutations of Coarse Woven (CW), Fine Woven (FW), and Unidirectional (UD) E/glass fiber sheets, taking into account the longitudinal vascular bundles strengthened by organic matrix. Samples were fabricated employing a modified hand laying up method by using mechanical pressure to obtain better surface finishing and interlaminar adhesion compared to conventional hand layering up methods. To evaluate the corresponding crashworthiness parameters and characterize the crushing behavior of composite tubes, quasi-static axial compressive loading was done. The numerical simulations were validated versus experiments by a commercial finite element (FE) LS-DYNA integrating material model 54. The predicted load-displacement curves and failure mechanisms of FE analysis demonstrate acceptable correlations with visual observations during experimentation. Furthermore, the parametric numerical was performed to examine the effect of different distributions of vascular bundles. The FE analysis results revealed that the crushing behavior of bio-inspired composite tubes depended substantially on layering configuration and the stacking sequence design. The outcomes showed that the combination of woven and unidirectional fibers, respectively, located in the inner layer and hoop direction provide the optimal layering configuration design in terms of crush length efficiency, crush load efficiency, Specific energy absorption, stable progressive crushing, and better manufacturing quality.

Investigations on crush behavior and energy absorption characteristics of GFRP composite conical frusta with a cutout under axial compression loading

The changes in energy-absorption and deformation characteristics of thin-walled E-glass fiber reinforced composite conical frusta upon introduction cutouts were studied through quasi-static axial compression loading. The 15°, 18° and 21° semi-apical angled conical frusta with a circular, square, and elliptical cutout were axially compressed, and its crush-force-efficiency, energy-absorption, and specific-energy-absorption (SEA) characteristics were analyzed. Further, the ABAQUS® finite element software was used to simulate the crush behavior of perfect and imperfect conical frusta, and the corresponding results were compared with the experimental results, and the results are reported in this article.

Experimental studies on quasi-static axial crushing of additively-manufactured PLA random honeycomb-filled double circular tubes

The Voronoi-based random honeycomb cylindrical shell with specific mesostructures was constructed programmatically and additively manufactured on material of polylactide (PLA). Then, a new PLA random honeycomb-filled double circular tube (PLA-RHFDCT) was proposed. The mechanical performance of the PLA-RHFDCTs in terms of deformation mode, crushing response and energy absorption was studied experimentally by carrying out the quasi-static axial compression loading. A parametric study was performed to evaluate the influence of tube sizes and the mesostructures of honeycomb cores on the crushing resistance and energy absorption capacity of the PLA-RHFDCTs. Results indicate that the cell configuration dominates the deformation modes of PLA honeycomb cylindrical structure. For the PLA-RHFDCTs, the deformation and the bearing capacity are mainly determined by the wall thicknesses of tubes. The introduction of PLA honeycomb core enhances the mechanical performance and affects the localized buckling of the PLA-RHFDCTs due to both the in-plane and out-of-plane crushing resistance of honeycomb core structures. Compared with the parameter of cell irregularity, the relative density of honeycomb cylindrical cores exhibits a higher influence on the energy absorption performance of the PLA-RHFDCTs, though the relatively low crushing strength of PLA honeycomb cylindrical structures.

Effect of infill pattern, density and material type of 3D printed cubic structure under quasi-static loading

The present research work is aimed to investigate the effect of infill pattern, density and material types of 3D printed cubes under quasi-static axial compressive loading. The proposed samples were fabricated though 3D printing technique with two different materials, such as 100% polylactic acid (PLA) and 70% vol PLA mixed 30% vol carbon fiber (PLA/CF). Four infill pattern structures such as triangle, rectilinear, line and honeycomb with 20%, 40%, 60%, and 80% infill density were prepared. Subsequently, the quasi-static compression tests were performed on the fabricated 3D printed cubes to examine the effect of infill pattern, infill density and material types on crushing failure behaviour and energy-absorbing characteristics. The results revealed that the honeycomb infill pattern of 3D printed PLA cubic structure showed the best energy-absorbing characteristics compared to the other three infill patterns. From the present research study, it is highlighted that the proposed 3D printed structures with different material type, infill pattern and density have great potential to replace the conventional lightweight structures, which could provide better energy-absorbing characteristics.

Improvement of energy absorption of expanded metal tubular structures under compressive loads

Herein, several approaches with the aim of improving the crashworthiness performance of expanded metal tubes were assessed experimentally and numerically. In this regard, various expanded metal tubes were produced out of expanded metal sheets including expanded metal tubes, stiffened expanded metal tubes, foam-filled expanded metal tubes and multi-layered expanded metal tubes. Their crashworthiness performance was evaluated under quasi-static axial compressive loading. The effect of cross-sectional type (square and circular) and cell size (large and small) were also evaluated. Results showed the significant effect of cell size on the crashworthiness performance of expanded metal tubes, while the cross-sectional type had negligible effect. Moreover, the energy absorption properties of expanded metal tubes improved through welding expanded metal sheets in the core (stiffened expanded metal tubes), embedding expanded metal tube in foam, and placing several expanded metal tubes concentrically. Among the studied approaches, the foam-filled expanded metal tubes exhibited the most stable compressive load-displacement response, which is desirable for energy dissipation. Furthermore, the load-displacement responses of prepared expanded metal tubes were also predicted acceptably by the proposed finite element modeling. Finally, the effects of expanded metal tube parameters on the crashworthiness performance of tubes were investigated numerically.

Experimental and numerical studies on failure and energy absorption of composite thin-walled square tubes under quasi-static compression loading

Abstract To analysis the failure and energy absorption of carbon fiber reinforced polymer (CFRP) thin-walled square tube, the quasi-static axial compression loading tests are conducted for [±45]3s square tube, and the square tube after test is scanned to further investigate the failure mechanism. Three different finite element models, i.e. single-layer shell model, multi-layer shell model and stacked shell mode, are developed by using the Puck 2000 matrix failure criterion and Yamada Sun fiber failure criterion, and three models are verified and compared according to the experimental energy absorption metrics. The experimental and simulation results show that the failure mode of [±45]3s square tube is the local buckling failure mode, and the energy are absorbed mainly by intralaminar and interlaminar delamination, fiber elastic deformation, fiber debonding and fracture, matrix deformation cracking and longitudinal crack propagation. Three different finite element models can reproduce the collapse behaviours of [±45]3s square tube to some extent, but the stacked shell model can better reproduce the failure mode, and the difference of specific energy absorption (SEA) is minimum, which shows the numerical simulation results are in better agreement with the test results.

Energy Absorption Analysis and Multi-objective Optimization of Tri-layer Cups Subjected to Quasi-static Axial Compressive Loading

In this paper, the energy absorption features of tri-layer explosive-welded deep-drawn cups subjected to quasi-static axial compressive loading are investigated numerically and experimentally. To produce the cups, tri-layer blanks composed of aluminum and stainless steel alloys were fabricated by an explosive-welding process and formed by a deep drawing setup. The quasi-static tests were carried out at a rate of 2 mm/min. Based on the structure of the tri-layer cups and to calculate the energy absorption features of these structures, a numerical model was established and validated by experimental findings. Moreover, based on a surrogate model and using non-domain sorting genetic algorithm II, multi-objective optimizations were performed on specific energy absorption and initial peak load. The results indicated that the total absorbed energy and mean crush force of the pure stainless steel tri-layer cup were about 5.8 and 5.7 times the values of those for the pure aluminum specimen, respectively.

Quasi-static crushing response of square hybrid carbon/aramid tube for automotive crash box application

One of the essential automotive parts is a crash box, which is essential for initial kinetic energy absorption. However, both vehicle weight and energy-absorbing performance of crash box requirements have to achieve. Recently, crash boxes made of hybrid materials have increasingly studied regarding their better crash performance and weight reduction effects compared to conventional metallic materials. Therefore, the aim of this study is to fabricate a hybrid carbon/aramid composite crash box with a hollow structure and to determine its mechanical properties under quasi-static axial compressive and tensile loading. This study shows that square hybrid carbon/aramid tubes provide an average 57.94 J energy absorption, average 0.72 kJ/kg specific energy absorption, average 62.46 kN crushing peak load, average 748.40 MPa compressive modulus and average 36.29 MPa maximum stress under quasi-static compressive loading. It is suggested that a square hybrid carbon/aramid tube could have the promising potential to replace aluminium or metallic structure to use as an automotive crash box for lightweight applications.

Effect of strut length and orientation on elastic mechanical response of modified body-centered cubic lattice structures

Lattice structures (LSs) have been exploited for wide range of applications including mechanical, thermal, and biomedical structures because of their unique attributes combining the light weight and high strength. The main goal of this research is to investigate the effect of strut length and orientation on the mechanical characteristics of modified body-centered cubic (BCC) LS subjected to a quasi-static axial compressive loading within linear elastic limit using finite element analysis. In this study, two sets of LS were built and analyzed in commercial finite element software, ABAQUS/CAE/EXPLICIT 6.16, using a “smart procedure,” which was developed for this research to reduce the computational time and increase the accuracy of results by creating hexahedral mesh elements. The first set comprises 13 models having fixed strut length with strut angle variation from 40° to 100° with a step of 5°. The second set also includes 13 models; however, having variant strut length, kept constant for a single unit cell and through the entire model but varied from one model to another, with the same strut angle variation as the first set. In addition, the BCC LS with a strut angle of 70.53° was replicated in both sets because it was considered as a reference model to compare the results with it. Furthermore, specimens of the reference model were fabricated by a fused deposition modeling- (FDM) based 3D printer using acrylonitrile butadiene styrene (ABS) material and tested experimentally under compression. Experimental results are observed to be in good agreement with those of the finite element simulation, hence the same loading and boundary conditions were adopted for all other models. It was observed that the fixed strut length BCC LS with a strut angle of 100° offers the highest modulus. However, the highest specific strain energy absorption and specific stiffness as well as the least value of weight were dictated by a variant strut length BCC LS with a strut angle of 40°.

Investigation of the numerical, experimental, statistical and optimization of thin-walled energy absorber with novel configuration using response surface method under axial loading

In this study, aluminum thin-walled cylindrical absorbers for crashworthiness are investigated to introduce a novel system with better energy absorption and crushing characteristics under quasi-static axial compressive loading. The inside of the thin-walled cylinders is meshed with a square welded from vertices to the thin-walled cylinder. Here, the response surface method, which is one of the design of experiments techniques has been used to examine the effect of the parameters on energy absorption, initial peak crushing force, specific energy absorption per unit mass and energy absorption per length. The variables of thickness (t), height (h) and length of square (l) of the thin-walled cylinder were considered in three levels and initial peak crushing force, specific energy absorption per unit mass and energy absorption per length were selected as response. The specimens were analyzed under a quasi-static compressive test at a constant speed of 10 mm/min. Subsequently, for further investigation, the experimental results were compared with those obtained from the finite element simulation using Abaqus software, which indicated desirable accuracy. To decrease the solution time in this numerical analysis, the speed was set at 0.5 m/s. Finally, the experimental results were compared with the simulation ones, which showed acceptable compatibility. Further, there are the equations obtained from the multi-objective optimization testing design. The results indicated a linear relationship of thickness with responses, nonlinear relationship of height with responses, linear relationship of length of square with initial peak crushing force, and nonlinear relationship with specific energy absorption per unit mass and energy absorption per length.

A novel method for enhancing the energy absorption characteristics of circular tubular structures under axial splitting

The present research is an attempt to introduce a novel method for axial splitting of brazen tubes in order to eliminate the dependency of the conventional splitting mechanism on a hardened steel die and improve the energy absorption capability of the presented method. Some circular tubular samples were cut out from commercial brazen tubes and the specimens were then filled with natural rubbers with different shore hardness. For this purpose, the tubes were filled by raw rubbers and placed in an autoclave for a specific time at a controlled temperature to complete the curing process of rubbers. Some slits were created on one side of the rubber-filled tubes and the specimens were compressed during quasi-static axial compression loading between two rigid plates. Based on the experimental results, the effects of diameter and wall-thickness of the tubes, length and number of initial slits, rubber shore hardness and length of initial extra rubber on the energy absorption characteristics of the specimens are investigated. Also, experimental results of the presented splitting method are compared with those of the conventional splitting method (using conical dies for splitting of empty tubes) to find an optimized energy absorber. It was found that in comparison with the conventional splitting method, the presented technique eliminates the restrictions of using almost heavy dies which significantly decrease the overall mass of the system and moreover increases total energy absorption and keeps crush force efficiency in the range of classical splitting.

Quasi-static Axial Crushing Behavior of Thin-walled Circular Aluminum Tubes with Functionally Graded Thickness

In this paper, the crushing behavior of circular aluminum thin-walled tubes with functionally graded thickness (FGT) are investigated experimentally. To this aim, three different thickness grading patterns are introduced to the longitudinal direction of tubes using a grading function, and then specimens are tested by universal testing machine under quasi-static axial compression loading. In addition, to show the efficiency of FGT tubes, the quasi-static axial crushing performance of FGT tubes are compared with their uniform thickness (UT) counterparts at the same weight. The test specimens have been made of commercial quality 6060 aluminum alloy and manufactured with computerized numerical controlled (CNC) machining workbench. Initial crush force (ICF), total energy absorption (EA), specific energy absorption (SEA) and mean crush force (MCF) values are measured from the tests to infer the quasi-static axial crushing performance of the tubes. The test results showed that the energy absorption characteristics of FGT tubes are better than the UT counterparts and FGT tubes allow effective control of the energy absorption parameters when compared with the UT tubes due to their varying stiffness along their longitudinal direction.

Axial crushing analysis of empty and foam-filled brass bitubular cylinder tubes

To reduce loss from collision, energy absorbers are used which dissipate energy upon deformation and folding in order to prevent damage to critical parts of a structure. In this study, the empty and polyurethane foam-filled bitubular tubes made from brass with circular section were subjected to quasi-static axial compression loading. Nonlinear dynamic finite element analyses are carried out to investigate the details concerning crushing process by using explicit finite element code ABAQUS. Satisfactory agreements are achieved between the finite element and the experimental results. The validated finite element model was then used for the parametric studies, in order to determine the effect of the empty and filler tube geometry parameters (i.e. wall thickness, semi-apical angle) and loading parameters (i.e. impact mass, impact velocity) on the Dynamic Amplification Factor. The results highlight the advantages of using the brass bitubular circular tubes as energy absorber.

Crushing behavior of metallic thin-wall tubes with triggering mechanisms due to quasi-static axial compression

The current work is concerned with the axial crushing behavior of metallic thin-wall tubes containing prescribed through-hole triggering mechanisms. A square tube without any defects was studied in order to verify the accuracy and adequacy of the simulated crushing response of the tube due to quasi-static axial compression loading. The power law plasticity strain hardening model was utilized to describe the stress strain relationship for the metallic tubes in question. Implicit nonlinear finite element solvers in LS-DYNA were used to simulate the quasi-static compression behavior for the AA6060-T4 aluminum square tubes. The SHIMAZDU AG-X material tester was used to conduct quasi-static compression tests. The associated sensing facilities were used to measure the quasi-static crushing force and the axial crushing length of the aluminum square thin-wall tubes loaded at a stroke-rate of 10 mm/min. Furthermore, the quasi-static crushing behavior of square aluminum tubes with through-holes was also numerically studied. In comparison with the compression response of square tubes without holes, it was reported that an 11.7% decrease in the initial peak force for the square thin-wall aluminum tubes with a pair of circular holes was found. A modified circular-hole triggering mechanism located on the 1.5-mm pre-indented square tubes was also introduced, and this proposed design is found to be able to diminish the initial peak force by 14.6% when compared with that for an aluminum thin-wall tube without hole-defects.

Bitubular square tubes with different arrangements under quasi-static axial compression loading

This paper attempts to present new methods for improving the crashworthiness parameters of square thin-walled energy absorber components. Experimental and finite element analyses were performed on bitubular square thin-walled tubes with different arrangements under quasi-static axial compression loading. 15 tests were conducted on single and bitubular square aluminum tubes. To investigate the energy absorption capacity of bitubular tubes and assess the effect of different parameters on crashworthiness characteristics of these tubes, finite element code LS-DYNA was utilized. At first, single tubes were investigated, and then bitubular tubes with two different arrangements including Parallel and Diamond arrangements were studied. Results show that absorbed energy by bitubular tubes is more than the sum of the energy absorbed by inner and outer tubes loaded separately which is due to the interaction effects between inner and outer tubes. Diamond arrangement was used to highlight the role of interaction effect in energy absorbing as progressive buckling modes of the tubes change because of the interaction. Also, the effect of length difference in inner and outer tubes was inspected and the main advantage of bitubular tubes is introduced when the inner tube is shorter than the outer. In this case, the peak load remains the same as that of the outer tube while mean load increases considerably.

Numerical and Experimental Investigations on the Expansion Tube Energy Absorber

Expansion tube energy absorber is of interest in bumper device on the spacecraft, for example the seat-bumper and its crushing characteristics have shown an excellent performance. This paper contributes to the analysis and investigation of the crushing characteristics of the expansion tube energy absorber, by simulating the response of the 2Al2T4 expansion tube subjected to quasi-static axial compressive loading, using the LS-DYNA finite element code. Corresponding tests were conducted to serve as comparison purpose. Satisfactory level of agreement between simulation and testing results was obtained regarding the main characteristics of the tested expansion tubes such as peak compressive load, energy absorption and the overall compressive response. Formula of the crushing force deduced using plastic mechanic theory was checked. Impact model was also constructed and dynamic simulations were performed to investigate the axial impact response of the expansion tube energy absorber. The simulation results of quasi-static and dynamic compression response of the expansion tube are very similar.