Quasi-static Axial Loading Research Articles

Energy absorption of thin-walled multi-cell tubes with DNA-inspired helical ribs under quasi-static axial loading

Energy absorption of thin-walled multi-cell tubes with DNA-inspired helical ribs under quasi-static axial loading

Local reinforcement of adhesively bonded square shape aluminum energy absorber with CFRP under quasi-static axial loading: An experimental and numerical study

This study presents experimental and numerical investigations on the effects of composite ply angle, thickness and number of layers on energy absorption behavior of adhesively bonded carbon fiber-reinforced plastic/aluminum hybrid structure under quasi-static axial loading. This paper aims to use the advantages of adhesive bonding for the local strengthening of a square shaped aluminum energy absorber by composite and as a result achieving desirable energy absorption behavior prior to failure in the connection and without heterogeneous deformation of the structure while reducing the weight of the structure and usage of material and at the same time obtaining favorable results compared to the traditional ways like reinforcing the aluminum structure with composite globally. For this purpose, two models were made and analyzed; one reinforced with four L-shaped composites adhesively bonded using Araldite 2015 to four outside corners of the aluminum square and the other reinforced locally to four corners from within the square. Finite element model was developed for analysis of these hybrid structures. Five different ply angles for composite and multiple number of composite layers varied from 2 to 8 layers under the same and different thicknesses were investigated. Moreover an alpha factor has been determined to measure the importance of local reinforement of the square shape aluminum energy absorber by L-shaped composites. The results showed that compared to aluminum and aluminum with global composite reinforcement energy absorbers, due to the adhesive connection between aluminum and composite in the locally reinforced CFRP/aluminum specimen, the composite had better energy absorption by following the collapse pattern of aluminum and creating a continuous collapse and failure modes. The results indicated good coordination and agreement between the simulated models and the experimental tests. The findings from this experiment demonstrates significant potential for local reinforcement of structures employing adhesives. Utilizing such connections and the ability to strengthen specific areas based on arbitrary geometry and strengthening location could offer substantial opportunities in constructing lightweight structures with high energy absorption across diverse applications.

Experimental evaluation on the axial crushing performance of BFRP-bamboo winding composite hollow components

In order to study the quasi-static axial crushing performance of BFRP-bamboo winding composite hollow components, considering the cloth ratio of BFRP (0%~14.68%) the number of BFRP layers (0 layer~4 layers) as an influencing factor, 20 tube specimens were designed for quasi-static compression tests. In this paper, the failure modes of the specimens under quasi-static axial compressive load are presented with the relevant load-displacement curves. The deformation types were carefully studied to evaluate the compressive crushing indicators of the specimens. The test results showed that when the cloth ratio of BFRP increased from 0 to 14.68%, the specific energy absorption (SEA), the mean crushing force (MCF) and the crushing load efficiency (CFE) increased to some extent, whilst the initial peak crushing force (PCF) did not show any trend. When compared with those of the bamboo winding hollow components (BT), the SEA, MCF and CFE of BFRP-bamboo winding composite hollow components with four layers of BFRP winding outside of BT (BBT4) increased by 87.53%, 194.37% and 255.59% respectively. Compared with other composite hollow components such as composite wrapped hollow components (CWT) and carbon reinforced composite hollow components (CRCT), BFRP-bamboo winding composite hollow components (BBT) showed superior crushing resistance while offering the advantages of light weight.

Numerical and experimental study of energy absorption in multilayer tubes manufactured through spinning forming process under quasi-static axial loading

Currently, dual-layer tubes play a pivotal role in sectors like nuclear, oil, gas, and steam generation. Recent research focuses on enhancing energy absorption in these tubes using the spinning forming process. This thin-walled nature benefits their application as efficient energy absorbers in transportation like trains and aircraft. A novel approach integrates coarse and fine-threaded ridges between steel and aluminum layers to create a mechanical interlock using the spinning forming technique. This interlock enhances the bond through flow forming, resulting in robust dual-layer tubes. Interlayer connection strength is rigorously tested through shear tests, pre and post flow forming, indicating a significant post-flow forming enhancement. This process substantially bolsters the overall structural integrity of dual-layer tubes. In crush tests, both single-layer and dual-layer steel and aluminum tubes undergo pressing through flow forming. Comparative analysis of energy absorption parameters—specific energy and crushing percentage—reveals notable performance differences. An annealed version of the tube with an aluminum layer is also included due to prior aluminum layer failures. Among dual-layer samples, the flow formed variant with fine-threaded ribs exhibits superior energy absorption and bonding. Finite element simulation of the pressed dual-layer sample demonstrates an 8.42 % deviation between simulated and experimental energy absorption outcomes. The study highlights that tightly bonded layers result in enhanced bonding characteristics.

Preparation and mechanical properties of in-situ aluminum foam-filled SS304 corrugated tubes with metallurgical bonding

In this work, AlSi10Ca3Mg0.5 alloy foam-filled SS304 corrugated tubes (FFCTs) were prepared by melt route with surface modification of the tube substrate prior to in-situ foam filling. Results showed that successful metallurgical bonding can be achieved between aluminum foam and the tube with surface modification. Under quasi-static axial loading, the foam core within FFCTs were compressed densely from top to bottom in sequence, showing an axisymmetric deformation mode. Due to the enhanced bonding between the foam and the tube, FFCTs with surface modification demonstrated approximately ∼19 % increase in specific energy absorption compared to FFCTs without surface modification.

Investigating the impact of cross-sectional area on the crushing characteristics of axially-loaded hemispherical composite shells

The research focus has shifted towards lightweight structures with high energy absorption capabilities due to advancements in automotive safety technology. This study specifically investigates the impact of cross-sectional area on the energy absorption characteristics of hemispherical composite shells. The experimental phase involves characterizing a glass fiber epoxy composite, followed by the manufacture of hemispherical composite shell specimens with varying cross-sectional areas. These specimens undergo quasi-static axial compressive loading, and the energy absorption parameters are analyzed. The results indicate a significant influence of the composite cross-sectional area on the crushing behavior of hemispherical shells, with a observed decrease in specific energy absorption as the cross-sectional area increases. Additionally, a 3D Finite Element (FE) model is created using ABAQUS FE code to numerically simulate the crushing process. The model’s predictions are compared and validated against experimentally measured values, demonstrating a satisfactory correlation.

Kinematics, kinetics, and new insights from a contemporary analysis of the first experiments to produce cervical facet dislocations in the laboratory.

The first experimental study to produce cervical facet dislocation (CFD) in cadaver specimens captured the vertebral motions and axial forces that are important for understanding the injury mechanics. However, these data were not reported in the original manuscript, nor been presented in the limited subsequent studies of experimental CFD. Therefore, the aim of this study was to re-examine the analog data from the first experimental study to determine the local and global spinal motions, and applied axial force, at and preceding CFD. In the original study, quasistatic axial loading was applied to 14 cervical spines by compressing them between two metal plates. Specimens were fixed caudally via a steel spindle positioned within the spinal canal and a bone pin through the inferior-most vertebral body. Global rotation of the occiput was restricted but its anterior translation was unconstrained. The instant of CFD was identified on sagittal cineradiograph films (N = 10), from which global and intervertebral kinematics were also calculated. Corresponding axial force data (N = 6) were extracted, and peak force and force at the instant of injury were determined. CFD occurred in eight specimens, with an intervertebral flexion angle of 34.8 ± 5.6 degrees, and a 3.1 ± 1.9 mm increase in anterior translation, at the injured level. For seven specimens, CFD was produced at the level of transition from upper neck lordosis to lower neck kyphosis. Five specimens with force data underwent CFD at 545 ± 147 N, preceded by a peak axial force (755 ± 233 N) that appeared to coincide with either fracture or soft tissue failure. Re-examining this rich dataset has provided quantitative evidence that small axial compression forces, combined with anterior eccentricity and upper neck extension, can cause flexion and shear in the lower neck, leading to soft tissue rupture and CFD.

Effect of Aspect Ratio, Rotation, and Eccentricity of Square Section Nested Thin-Walled Tubes on Their Energy Absorption Characteristics Under Quasi-Static Load

In this research, energy absorption characteristics of nested thin-walled aluminum structures with square cross-section have been investigated, and the effect of the three parameters: eccentricity, rotation, and tube aspect ratio on the energy absorption characteristics of the structure has been studied. The properties investigated were the specific energy absorption and crush force efficiency. An aluminum 1050 sheet was used to build the tubes. After making the samples and determining how the tubes were placed with each other, the structures were subjected to quasi-static axial loading. Also, for parametric investigations, the behavior of the structures was simulated using LS-Dyna software. The results showed that the simultaneous effect of the three desired parameters has increased the specific absorbed energy and the crushing force efficiency. When the tubes were at maximum eccentricity, the specific energy absorption and crushing force efficiency increased by reducing the aspect ratio and rotation angle. On average, the best sample’s specific energy absorption and crush force efficiency increased by 41.9% and 22.2%, respectively, compared to the single tube.

Energy absorption of central self-similar honeycombs under quasi-static axial load

At present, improving the energy absorption capacity of lightweight degradable polymer honeycombs is crucial for one of the future engineering applications and bio-inspired strategy based on hierarchy is considered an efficient method for designing honeycomb structures. To improve the energy absorption performance and stability of polymer honeycombs, this study develops three central self-similar bio-inspired honeycombs combining the microstructure of horsetails and designs different connections between the two walls and connecting structures for the central self-similar honeycombs. Bio-inspired honeycombs are fabricated using toughened polylactic acid (PolyMax™ PLA) through fused deposition modelling and subjected to axial compression tests. The finite element (FE) models of the bio-inspired honeycombs are developed to simulate the axial compression process and verified with experimental results. Results show that the connecting structures distributed on the outer wall of the central self-similar honeycombs considerably improve the energy absorption performance of the bio-inspired honeycombs. In the double-cell honeycombs, connecting structures interact with the cell walls, leading to the formation of more folding lobes on the cell walls and increased cell wall utilisation. Furthermore, the effects of geometrical parameters on the energy absorption performance of the bio-inspired honeycombs are investigated. Suitable connecting structure size and cell wall thickness can improve the energy absorption performance and stability of the honeycombs. In addition, the theoretical calculation models of the three bio-inspired honeycombs are established, and the errors with the FE calculation results are within 6 %, which verifies the accuracy of the theoretical models.

Peridynamic correspondence model with strain gradient elasticity for microstructure dependent size effects

This study presents a peridynamic (PD) correspondence model with strain gradient elasticity (SGE) to capture size effect on strength of nano- and micro-scale structures. The classical elasticity theory lacking a length scale parameter does not account for the microstructure-dependent size effects. Strain Gradient (SG) elasticity is an extension of the classical elasticity with a length scale parameter(s) which can be linked to the microstructure of the material. Peridynamic theory introduces damage into the constitutive relations in a natural way by allowing for interactions of a material point within its horizon which is referred to as the internal length parameter. The correspondence model of the PD theory permits the incorporation of the constitutive relationship of SG theory. Therefore, the present approach combines the effects of PD and SGE length scale parameters on the stiffness and strength of the material. The resulting equations present two length parameters: the horizon of a material point in PD theory and the characteristic length in SGE theory. The PD equation of motion with SGE (PDSG) is free of spatial derivatives and allows for the imposition of classical and nonclassical boundary conditions. The PDSG is first applied to investigate the deformation response of a one-dimensional nanoscale film subjected to a quasi-static tensile load and a dynamic load through an initial constant strain. The static response is compared with the analytical solution for varying ratio of SG length parameter to PD horizon. The dynamic response is compared with a computational solution while satisfying the nonclassical boundary conditions. Subsequently, the PDSG is applied to study the deformation response of a two-dimensional nanoscale film subjected to a quasi-static axial load and a specified tangential end displacement. These two cases are considered under special displacement constraints to compare with the available analytical solutions. Subsequently, a two-dimensional nanoscale film with or without an internal crack is subjected to uniform tensile loading. Finally, crack propagation is simulated under incremental displacement loading. The results capture the analytical predictions and the expected increase in stiffness with increasing ratio of SG length parameter to PD horizon.

Experimental investigation of 3D printed bio-inspired Xylotus lattice structure for energy absorption under quasi-static axial loading conditions

The demand for robust, lightweight polymer components in various industries has prompted researchers to turn to nature's structures for inspiration. Leveraging Polymer Additive Manufacturing (PAM), specifically Fused Filament Fabrication (FFF), complex bio-inspired lattice polymer structures have been successfully realized. This experimental study focuses on the development of novel 3D printed bioinspired Xylotus lattice structure with elements inspired by xylem and lotus. The primary goal was to evaluate the deformation behaviour and energy absorption characteristics of 3D printed Xylotus lattice structure under quasi-static compressive loading and compare the results with existing research. The hybrid (Xylotus) structure of xylem and lotus exhibited a sequential failure pattern, starting with axial cracks and followed by buckling. Furthermore, an analysis of energy absorption showed that the xylem lattice outperformed the lotus lattice, thanks to its robust tubular elements. Notably, the Xylotus lattice displayed the highest energy absorption capabilities, capitalizing on features from both lotus and xylem. The energy absorption of the Xylotus lattice structure surpassed that of the xylem and lotus structures by 13% and 29.2%, respectively. The xylotus lattice structure exhibited 38% higher energy absorption compared to the existing research. Moreover, the specific energy absorption of the Xylotus lattice structure outperformed the lattice structures reported in the existing research by 37%. This study offers valuable insights into the structural behaviour, energy absorption, and specific energy absorption of bio-inspired lattice Xylotus structure. The findings contribute significantly to the design of resilient, lightweight components, supporting the advancement of bio-inspired structures for diverse applications in various industries.

Experimental & numerical study on hybrid aluminium/GFRP thin-walled column under quasi-static axial loading

This paper discusses a research study to examine the behaviour of a circular thin-walled column subjected to quasi-static axial loading. Pure aluminium and hybrid aluminium/GFRP thin-walled column were experimentally tested, then a numerical simulation model using LS-Dyna approached the results. A parametric study was investigated with several material model parameters for a deeper understanding of the woven prepreg GFRP composite modelling. It was found that the failure mode and crashworthiness parameters result would be affected by parameter variations. Therefore, the values used for these parameters were obtained by doing parameter calibration so that the load-displacement response of the thin-walled column is similar to experimental results. The further parametric study result showed that the composite layers wrapped around the outer wall could increase the capacity of the energy absorption thin-walled column. Adding thickness to the composite layers would increase crashworthiness parameters, including mean crushing force, energy absorption, and specific energy absorption under quasi-static loading. Furthermore, the proposed modelling strategy developed in this work can be used as a reference for modelling the thin-walled column made of hybrid material due to the limited comprehensive numerical parametric studies on hybrid thin-walled column.

Effect of 3D-Printed Honeycomb Core on Compressive Property of Hybrid Energy Absorbers: Experimental Testing and Optimization Analysis.

This paper presents an innovative method of constructing energy absorbers, whose primary function is to effectively transform kinetic energy into strain energy in events with high deformation rates. Hybrid specimens are proposed considering thin-walled windowed metallic tubes filled with 3D-printed hexagonal honeycombs made of PET-G and ABS thermoplastic. The patterned windows dimensions vary from 20 × 20, 20 × 30, 15 × 20 and 15 × 30 mm2. Although using polymers in engineering and thin-walled sections is not new, their combination has not been explored in this type of structure designed to withstand impacts. Specimens resist out-of-plane quasi-static axial loading, and test results are analyzed, demonstrating that polymer core gives the samples better performance parameters than unfilled samples regarding energy absorption (Ea), load rate (LR), and structural effectiveness (η). An optimization procedure using specialized software was applied to evaluate experimental results, which led to identifying the optimal window geometry (16.4 × 20 mm2, in case) and polymer to be used (ABS). The optimized sample was constructed and tested for axial compression to validate the optimization outcomes. The results reveal that the optimal sample performed similarly to the estimated parameters, making this geometry the best choice under the test conditions.

Grooves and Cross Section Effects on Energy Absorption of S-Shaped Tubes Under Axial Quasi-Static and Impact Loading

Grooves and Cross Section Effects on Energy Absorption of S-Shaped Tubes Under Axial Quasi-Static and Impact Loading

Phase-field crystal simulation of the evolution of voids in polycrystalline Au–Al bonds with elastic interaction and the Kirkendall effect

In this paper, the modified phase-field crystal (MPFC) model is employed to study the evolution of Kirkendall voids in polycrystalline Au–Al bonds under mechanical loading. The MPFC model can simulate the structural evolution of deformed pure nanocrystalline materials considering instantaneous elastic interactions. Therefore, coupling a concentration field evolved by the Cahn-Hilliard equation with a density field evolved by the existing MPFC model makes it possible to study the phase transformation of a binary system in the presence of mechanical deformation. Using this modified model, we focus on the morphology evolution of the voids in Au–Al bonds under different mechanical loadings. The semi-implicit Fourier spectral algorithm is applied to solve the six-order coupling dynamics equations. The Kirkendall porosity of the diffusion couple is computed and analyzed. The effects of quasi-static and cyclic axial tensile loads on the morphology of voids, and porosity of the system are investigated. It is found that the morphology of Kirkendall voids that result from applying a quasi-static load is different from those that result from applying a cyclic load.

Optimization of the octagonal origami tube energy absorption using the artificial neural network and heuristic method

This article presents a hybrid optimization approach for improving the crashworthiness characteristics of thin-walled metallic tubes using a unique multilayered origami pattern. In the quasi-static axial loading condition, a total of 120 thin-walled tube samples were simulated using the full factorial design method to assess the impact of geometric parameters on their crashworthiness behavior, including the dihedral angle, module number, and outer layer height. Additionally, based on the input parameters, an artificial neural network was implemented to estimate the mechanical response of the tubes. Then, to determine the ideal design parameters, a hybrid multi-objective optimization approach was used. The Technique for Order of Preference by Similarity to Ideal Solution technique was utilized to extract the optimal design to balance the objectives of energy absorption and initial peak force. The specific energy absorption of the optimal tube was discovered to be 68% higher than that of the base tube. The simulation results demonstrate that the proposed multilayered origami pattern provides a unique structure that improves the crashworthiness properties of the thin-walled metallic tubes.

RETRACTED: 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.

Crash Box Impact Energy Absorption

Abstract: Crashworthiness parameters like internal energy absorption and crush force efficiency are the key constants in evaluating the component crashworthiness and its safety in the design of automotive structures for crashworthiness, there is an immense requirement for null strain sub modules that provide a rigid room of survival area for the occupants and deformable sub modules. Which can dematerialize the kinetic energy effectively? The front crash box of an automotive car is one of the most important deformable components which dissipate kinetic energy while frontal crash, which is the most persistent crash situation, affects the entire automotive structural behavior. In this research, quasi-static axial loading response and crashworthiness characteristics of empty hollow tube have been investigated through experimental and numerical simulations. The axial quasi-static loading was executed at a feed rate to evaluate the crashworthiness constants of each sample against quasi-static loading. The supremacy of feed rate empty hallow structures were pursued. The numerical simulation of quasi-static test was performed in accordance with explicit finite element algorithm of LS-DYNA in order to investigate and justify the crashworthiness of each variety of specimens with experimental results.

Mesoscopic analysis and intra-layer progressive failure model of fused filament fabrication 3D printing GFRP

The deficiency of failure analysis methods severely hinders the civil engineering application of Fused Filament Fabrication (FFF) 3D printing composites. In order to comprehensively investigate the failure process, this paper innovatively proposes the concept of continuous printing filament hypothesis based on mesoscopic analysis. This hypothesis serves to characterize the interconnection status between glass fiber reinforced polymer (GFRP) filaments during FFF 3D printing. Building upon this hypothesis, a progressive failure model is established, which can predict the intra-layer failure process under axial quasi-static load accurately. In the failure model, both Mode-2D and Mode-3D failure criteria are employed to pinpoint intra-layer damage initiation, while damage evolution is depicted using a stiffness reduction mode based on the fracture energy criterion. Simultaneously, the fundamental orthotropic mechanical parameters are examined, and 24 variations of printing laminates are meticulously designed. The ultimate tensile strengths (UTS), encompassing both cross-stacking (2/8, 4/6, 5/5) and angle-stacking (30°, 45°, 60°), are tested and simulated using the progressive failure method established during this study. Experimental results show that the lower layers of composites exhibit stronger ultimate resistance due to their layer-by-layer characteristics. Compared to the experimental results, all the relative errors of UTS predicted by Mode-3D are less than 15%. Therefore, the accuracy and predictive capacity of the progressive failure model are affirmed by the experimental data.

Experimental and numerical investigation on crashworthiness of composite reinforced auxetic cellular tubes

This study aims to investigate the crashworthiness properties of thin-walled foam-filled Auxetic metal/composite cellular tubes under quasi-static and low-velocity impact axial loading. The specimens were fabricated using thin-walled steel tubes and Glass Fiber Reinforced Composite (GFRC) laminates. The crashworthiness characteristics including peak load, absorbed energy, specific absorbed energy, and failure mechanisms of the hybrid structures were studied and compared with individual hollow section and foam-filled Auxetic tubes. In addition, detailed FE simulations were performed using LS-DYNA software, which was verified by the experiments.