Crush Load Efficiency Research Articles

Investigating the mechanical properties and crashworthiness of hybrid PLA/GFRP composites fabricated using FDM-filament winding

The failure and crashworthiness performance of hybrid Polylactide (PLA)/Glass Fiber Reinforced Polymer (GFRP) composite tubes subjected to axial and radial quasistatic compression loads were investigated in the present study. The composite tubes are fabricated using hand lay-up and Fused Deposition Modeling (FDM)-filament winding processes. The crashworthiness performance was studied using parameters such as the peak load, energy absorption, crush load, crushing load efficiency, and specific energy absorption. The highest peak loads from the compression test results in the axial and radial directions are calculated using variations in the filament winding PLA/GFRP (FPG) specimen, whose values were 16130.50 N and 12077.33 N, respectively. The highest mean crush load is found in the material variation with the FPG specimen, which is 5734.43 J/mm for axial loading and 4886.75 J/mm for radial loading. The highest energy absorption (EA) value is found in the material variation with the FPG specimen, which is 262.18 J for axial direction loading and 94.02 J for radial direction loading. The highest specific energy absorption (SEA) value is found in the material variation with the specimen Filament Winding PLA/GFRP, which is 16.92 J/g for axial loading and 10.98 J/g for radial loading. There are three main types of failure of the composite: matrix cracking, fiber damage, and folding. The study showed that by combining Additive Manufacturing and composite lamination, the hybrid PLA/GFRP specimen outperformed the existing structures.

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.

Energy absorption characteristics of stepped multi-cell columns subjected to transverse loading

Automotive bumper beam is a vital component that shields passenger and vehicle from harm and damage generated by catastrophic collapse. Previous investigations on its bending behavior have largely concentrated on multi-cell tubes with the same length, whereas stepped multi-cell structures have received less attention. In this paper, a novel stepped multi-cell configuration is proposed to improve the energy absorption characteristics of thin-walled structures under transverse loading. The finite element method is employed to analyze the crushing behaviors of the stepped multi-cell tubes. The numerical results reveal that the stepped multi-cell structures (SM2 to SM5) can reduce the initial peak force by 23.44–45.91% while increasing the energy absorption capacity, crush load efficiency, and specific energy absorption by 5.87–29.51, 38.29–139.45, and 5.87–29.51%, respectively, when compared to a conventional square tube (M1). In addition, the effects of wall thickness, section width, load angle, punch radius, and punch shape on the bending behaviors and energy absorption characteristics are examined. The results indicate that these factors have a considerable influence on the deformation features of M1 and SM2, which leads to a significant reduction in their bending energy absorption characteristics. These variables have no influence on the deformation modes of SM3, SM4, and SM5, and they present local indentation deformation with a high energy absorption efficiency. Increasing the number of layers improves the comprehensive performance of stepped multi-cell tubes, with SM5 exhibiting the best energy absorption characteristics under transverse loading.

Effect of stacking angles on crashworthiness of CFRP square tubes considering low-velocity impact damage

To enhance the residual energy‐absorption (EA) of low-velocity impact-damaged CFRP square tubes, this study investigates the influence of stacking angles on the damaged tubes' residual EA. Through simulation and theoretical analysis, a well-designed stacking angles is proposed to optimize the residual EA. Initially, a simplified method of low-velocity impact damage of composite materials is proposed, by which a discontinuous damage mechanics finite element model is established and experimentally verified. Subsequently, various layup sequences are examined, and their impact on energy absorption is evaluated using several performance indices, including initial peak load, average load, energy absorption, specific energy absorption, and crushing load efficiency. The findings demonstrate that the designed stacking angles significantly enhances the residual energy absorption of low-velocity impact-damaged square tubes. Moreover, the study verifies the efficacy of the stacking angles design by investigating actual damage conditions, encompassing factors such as damage size, location, and stress concentration.

THE EFFECT OF DIFFERENT WINDING CONFIGURATIONS ON THE CRUSHING RESPONSE OF HELICAL WOUND WOVEN GLASS/EPOXY COMPOSITE TUBES

The crushing behavior of polymer matrix composite tubes depends on several factors, such as diameter, fiber orientation, wall thickness, and winding configuration. The current work aims at understanding the effect of winding configuration with different helical overlap portions (none, quarter, and half) and the number of layers on the crushing response of woven glass/epoxy composite tubes subjected to quasi-static compression and impact loading. The length-to-diameter ratio is kept constant, for all the cases of the specimen considered. Crashworthiness parameters, such as mean crushing load, initial peak load, specific energy absorption, and crush load efficiency are compared for different cases. Damage and failure characteristics of different helical wound composite specimens are examined and compared with straight wound composite tubes made with a winding angle of 0°. The study shows that the energy absorption capacity of helical wound specimens increases in almost the same proportion as the helical overlap portion increases from no overlap to half overlap. Also, experimental results for composite tubes having different helical overlap portions suggest that the helical overlap portion can be an important parameter in achieving tailor-made energy absorption properties with inbuilt triggering features.

Effects of Temperature on Axial Crushing Behavior of Circular Multi-Walled Tubes

In this work, the impact of temperature on the crushing performance of multi-walled tube (MWT) were investigated using a combined experimental, theoretical and numerical method. The MWT was fabricated using extrusion technology, and the temperature-dependent axial crushing experiment was performed on a hydraulic testing machine. The results show that the peak crushing force (PCF), the mean force (Pm) and the specific energy absorption (SEA) decreased near-linearly by 21.7%, 30.7% and 30.7% as the temperature increased from 25 °C to 250 °C, while the crushing load efficiency (CLE) was insensitive to temperature. The average forces obtained via numerical prediction, theoretical analysis and experimental testing were basically consistent. The numerical results indicate that varied temperature alters the number of dominant wavelets and the relative lateral deflections of MWT. In addition, compared with the competitive structures, the energy absorption property of MWT is excellent at high temperatures.

Energy absorption capability of laterally loaded glass/epoxy tubular components containing halloysite nanotubes

The crashworthiness capability of laterally loaded glass/epoxy (GFRE) tubular components containing halloysite nanotubes (HNTs) was explored in this article. GFRE components filled with 0, 1, 2, 3, and 4 weight percent (wt.%) of HNTs were created using wet-wrapping by hand lay-up technique. For the laterally loaded tubes, the crushing load and the energy absorption versus displacement responses were presented. In addition, distortion histories were tracked. The crashworthiness analysis was carried out by evaluating different indicators, i.e., initial crush load [Formula: see text], average crush load ([Formula: see text]), crush load efficiency (CFE), energy absorption (U), and specific absorbed energy (SEA). Two parameters of the Weibull distribution were employed to assess the experimental findings statistically. In addition, mathematical regression models were built to predict the energy absorption indicators. Experimental results demonstrated that an unfilled tube demonstrated the largest CFE of 1.84, while the maximum [Formula: see text] was demonstrated by a tube filled with 2 wt.% of HNTs with a value of 3.70 kN. Additionally, the tube filled with 4 wt.% of HNTs represents the extremes [Formula: see text], U, and SEA with values of 4.26 kN, 128.82 J, and 3.84 J/g, respectively. Due to their improved crashworthiness characteristics, GFRE filled with 4 wt.% of HNTs is suitable for use as a crashworthy device in automobiles.

Improving the crashworthiness of carbon fiber-reinforced composite channel section structure through controllable failure mechanisms

To improve the crashworthiness of the composite channel section structure (CCSS), three external triggers including ditch plug trigger (DPT), trapezoidal groove trigger (TGT), and v-groove trigger (VGT) are proposed. A progressive damage model for CCSS is developed considering the damage initiation and evolution of intra- and inter-ply. Based on the model, the effects of the size of the external trigger and the friction coefficient between the external trigger and the structure on the axial energy absorption characteristics and failure modes of CCSS are investigated. The results show that the external trigger has a large influence on the failure process. The increase in ditch height of DPT is beneficial to improve the load-bearing capacity of the structure in the middle stage of crushing. Compared to DPT and TGT, VGT is more effective in decreasing the initial peak load and increasing the crushing load efficiency. The failure mechanisms of CCSS induced by the external trigger are revealed. The proposed external trigger can induce specific failure modes, and the structure tends to slide toward the middle after contact with TGT and VGT. The increase of the friction coefficient between CCSS and TGT or VGT can improve energy absorption. The results of the study can provide a reference for the design of external triggers for CCSS.

A Novel Lattice Structure for Enhanced Crush Energy Absorption

the energy absorption capacity of a few common lattice structures printed out of PLA using fused deposition modeling and proposes an improved lattice structure. Simple cubic (SC), honeycomb (HC), body-centered cubic (BCC), and novel PeckGy80 (PG80) lattice structures were subjected to compressive tests. The quasi-static load-displacement behavior of lattice specimens was characterized in terms of specific energy absorption and crush load efficiency. The damage mechanisms were then related to energy absorption. Cracks and brittle fractures occurred in all lattice structures during the crush test. Different lattice structures induced different damage mechanisms, significantly affecting their energy absorption. SC lattice structure showed structural separation at a small displacement, rendering it an ineffective energy absorber. BCC and HC lattice structures demonstrated almost identical shear band failure modes. The PG80 lattice structure, although made of brittle PLA, displayed progressive failure from the bottom layer to the upper layers, exhibiting both a high peak load and stable post-yield behaviour. This damage mode enabled the PG80 lattice to be far superior in terms of specific energy absorption to HC, SC, and BCC lattice structures.

A bi-factorial hierarchical honeycomb with promising crushing resistance

A bi-factorial hierarchical strategy is proposed to obtain a superior crushing resistance by optimizing the network section of honeycomb materials. A novel honeycomb named bi-factorial hierarchical honeycomb (BFHH) is developed, and its promising energy dissipation mechanism and progressive folding deformation are revealed by a compressive experiment. In the crashworthiness comparison, the material utilization and the crushing load efficiency of the BHFF-c16-h2 are superior to those of honeycombs with other hierarchical types with the same mass. Furthermore, a crashworthiness design on the bi-factorial hierarchical honeycomb is conducted to explore the effect of geometric parameters on crushing resistance. The increasing hierarchical factor h can improve the energy dissipation mechanism of the BFHH. The thickness-length ratio t/l can determine the deformation mode of the BFHH, which further controls the crushing loading efficiency of the BFHH. In addition, a dynamic matching strategy for the effective crushing distance coefficient is proposed to optimize the accuracy of theoretical analysis. The error of theoretical derivation is controlled to within 7%. Research findings can provide a guiding significance for the crashworthiness design of honeycomb materials.

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.

Dynamic crushing behaviors and enhanced energy absorption of bio-inspired hierarchical honeycombs with different topologies

In order to pursue good crushing load uniformity and enchance energy absorption efficiency of conventional honeycombs, a kind of bio-inspired hierarchical honeycomb model is proposed by mimicking the arched crab shell structures. Three bio-inspired hierarchical honeycombs (BHHs) with different topologies are designed by replacing each vertex of square honeycombs with smaller arc-shaped structures. The effects of hierarchical topologies and multi-material layout on in-plane dynamic crushings and absorbed-energy capacities of the BHHs are explored based on the explicit finite element (FE) analysis. Different deformation modes can be observed from the BHHs, which mainly depend upon hierarchical topologies and impact velocities. According to energy efficiency method and one-dimensional (1D) shock theory, calculation formulas of densification strains and plateau stresses for the BHHs are derived to characterize the dynamic bearing capacity, which is consistent well with FE results. Compared with conventional honeycombs, the crushing load efficiency and energy absorption capacity of the BHHs can be improved by changing the proper hierarchical topology and multi-material layout. These researches will provide theoretical guidance for innovative design and dynamic response performance controllability of honeycombs.

Crashworthiness of Circular Tubes with Rhombus Star Grooving Pattern

Thin-walled structures are widely used as energy absorbers in aircraft and automobiles. They have a high load-bearing capacity despite their small thickness. Due to their lightweight and high energy absorbing capacity, their application is becoming increasingly diverse. In this study, the structural response and crashworthiness performance of circular thin-walled grooved tubes were investigated under axial loading. Rhombus star grooving patterns were introduced to relatively short and thin tubes to enhance crashworthiness performance. The optimum crashworthy performance should provide a proper initial stiffness and a stable crushing force after the initial collapse. Experimental and numerical analyses have been conducted to investigate the influence of various geometrical patterns on crushing behavior and crashworthiness parameters. It was found that several multi-lobe diamond deformation modes can be triggered for a tube with a constant diameter to thickness ratio (D/t = 59.25). An increased number of lobes and folds led to higher specific energy absorption (SEA) and crushing load efficiency (CLE), up to 31% and 34.5% respectively. Parametric studies showed that groove depth can be used to achieve a desirable deformation mode that increases both SEA and CLE simultaneously. The proposed tubes would apply to the crashworthiness design of helicopter subfloor structures and vehicle bodies.

Study on the Effect of Geometrical Parameters of a Hexagonal Trigger on Energy Absorber Performance Using ANN.

Thin-walled structures are commonly used as energy absorbers in motor vehicles. Their function is to protect the structural components of vehicles and to absorb energy completely during collisions up to 20 km/h. This paper focuses on maintaining crush axiality during research. To verify the numerical analyses, physical specimens were made and then subjected to dynamic crushing. Force and shortening values as well as high-speed camera images were used for data analysis. Through time-lapse shots, plastic deformation within the crush initiator was observed. Such detailed analysis allowed the determination of the influence of hexagonal triggers in the form of notches on the post-buckling progressive analysis. In this paper, neural networks were used to examine the importance of each variable. Data from numerical analyses were used for this purpose. Based on the analyses performed, the effects of both the width and height of the triggers on the crush load efficiency (CLE) and total efficiency (TE) ratios can be seen. The width of the crush initiator has the greatest influence on Crash-box performance. Nevertheless, increasing both the height and the width of the initiator can result in crush non-axiality and underperformance of the energy absorber.

Energy-absorbing characteristics of hollow-cylindrical hierarchical honeycomb composite tubes inspired a beetle forewing

This paper investigates the superior energy-absorbing characteristics of hollow-cylindrical-joint hierarchical honeycomb composite tubes under axial quasi-static crushing. Biomimetic multi-cell tubes (BMCTs), inspired by the forewing of a beetle, were manufactured using the vacuum bag moulding method. Quasi-static compression tests were conducted to characterize the force–displacement response, the progression of failure, the crashworthiness characteristics, and the corresponding energy absorbing mechanisms. The experimental results show that the fiber orientation (α) has a significant effect on the energy-absorbing characteristics of these structures. The crush load efficiency (CLE) and specific energy absorption (SEA) tend to initially decrease and then increase with increasing α. It has also shown that the SEA of the BMCTs can be significantly affected by employing different fiber orientations. The highest SEA value measured on these structures, 77.3 J/g, is more than double of 34.9 J/g measured on the single circular tube counterpart. The energy-absorbing capacity of the composite structures is devisable and can be enhanced by integrated biomimetic design.

The Influence of Different Length Aluminum Foam Filling on Mechanical Behavior of a Square Thin-Walled Column

The demand for lightweight, strong structural profiles is currently high in the transport industry, mechanical engineering, and construction. Therefore, it is important to evaluate their properties, especially mechanical properties. The main objective of this paper is to determine energy absorption coefficients and evaluate the crush resistance of thin-walled aluminum profiles using numerical simulation and empirical verification. This paper presents the compression results of testing of thin-walled aluminum profiles filled with a porous material (cast aluminum foam). The numerical analysis was conducted using the software Abaqus/CAE. Aluminum material data were obtained from a static tensile test performed on a Shimadzu machine. The experiment was performed on an Instron CEAST 9450HES dynamic hammer. Profiles with three shapes of crush initiators filled with aluminum foam measuring 40 mm–200 mm in 20 mm increments were numerically tested. A sample with a concave initiator filled with foams of 40 mm, 60 mm, 80 mm, and 120 mm in length was used to verify the numerical analyses. Energy absorption coefficients were determined from the analyses. The results of both analyses were tabulated to show the percentage differences. The study showed an increase in the Crush Load Efficiency (CLE) index by up to 33% for samples with the same crush initiator. In addition, it was noted that the use of porous fill does not increase the value of initiating Peak Crushing Force (PCF), which indicates the generation of much smaller overloads dangerous for vehicle passengers.

Energy absorption analysis of square-circle hybrid section tubes under axial loading

Square-circle hybrid section (SCHS) tubes under axial loading which combine the advantage of square tubes and circular tubes are investigated. Firstly, effective finite element models of SCHS tubes are established to study the crashworthiness characteristics. Through a series of finite element models, the influence of the geometry on the behaviour of crashworthiness is studied, including relative size of square and circular sections in SCHS tubes and the position of connecting plates. The results show that compared with corresponding traditional multi-cell tubes, SCHS tubes improve the performance in energy absorption, with a maximum increase of 40.49%, while reducing peak force and improving crushing load efficiency. Moreover, the deformation of elements constituting the SCHS tube is analysed, and deformation of arc-plate elements could be classified into three typical modes. According to the observed deformation modes, the theoretical model is proposed to predict the mean crushing force of SCHS tubes. The theoretical results show that it is in good agreement with the numerical results.

Influence of layup, stacking sequence and loading rate on energy absorption of tension-absorber joints

“Tension-absorber” joints are bolted joints designed to absorb energy in a survivable crash landing, through an extended version of bearing failure. They have been proposed for use in future transport aircraft narrow-body composite fuselages. Herein, the influence of layup (percentage of each ply orientation), stacking sequence (exact location of each ply) and loading rate, on energy absorption is examined. Quasi-static and dynamic (3 m/s) tests are performed on pin-loaded IM7/8552 carbon-fibre/epoxy laminates. Seven layups and 11 stacking sequences are tested, with key variables being the percentage of 0° plies (from 12.5% to 62.5%), the position of the 0° plies, and the changes in orientation at ply interfaces. Performance measures include ultimate bearing strength (UBS), mass-specific energy absorption (SEA) and crush load efficiency (CLE). Computed tomography is used to examine damage progression in the quasi-static tests. It is found that the most important factor in maximising SEA is having small changes in orientation at ply interfaces. This is even more important than 0° content. A laminate with only 12.5% 0° plies, performed remarkably well due to its low changes in ply orientation. Laminates with a high SEA tend to have a low UBS. Highest UBS was for quasi-isotropic laminates. Increased loading rate results in increased UBS but decreased SEA. The results allow selection of a stacking sequence with a desired combination of UBS and SEA, and provide a valuable database for validation of composites damage models.

Crashworthiness analysis of multi-configuration thin walled co-axial frusta tube structures under quasi-static loading

Abstract In the present study crashworthiness performance of monolithic and co-axial multi-wall (double, triple, and four layered) frusta tube structures was investigated under the quasi-static axial loading. The developed layered frusta tubular structures having a total equivalent thickness of 2.3 mm were made of aluminium alloy AA-1080 sheet. A series of layered configurations were simulated and analysed using non-linear finite element analysis code LS-DYNA, keeping volume approximately the same as the monolithic frusta tube. For the effectiveness of the simulated results, double-tubular structure was examined through experimental results. A parametric study was performed by keeping taper angle constant as 5.71° with the variation in height (91.6 and 82 mm for double layered, 91.6, 86 and 78 mm for triple layered and 91.6, 87, 82 and 77 mm for four layered), thickness (2.3–0.4 mm) and diameter (smaller end diameter in the range of 42.8 mm–48.4 mm while larger end diameter varied from 61 mm to 64 mm) to analyse the crushing performance of layered structures. The crashworthiness performance indicator like peak force (PF), mean force (MF), energy absorbing capacity (EAC), specific energy absorption (SEA) and crush load efficiency (CLE) which is defined as the ratio of MF to the PF, were studied for the various layered frusta tubular structures. Moreover, optimization technique GRA (Grey Relational Analysis) was employed to obtain a better combination of multi-wall layered structures. With the increase in the layer, the initial peak force was reduced compared to the monolithic frusta. The optimization technique suggested the triple-layer configuration showed better crashworthiness performance.

Investigation on the temperature dependent out-of-plane quasi-static compressive behavior of metallic honeycombs

Abstract This study investigates the effect of temperature on the out-of-plane quasi-static compressive behavior of metallic honeycombs by numerical and theoretical methods. Adopting a temperature dependent elastic-perfectly plastic constitutive relation, the temperature dependent out-of-plane quasi-static compressive mechanical performance of Al5052 honeycomb is studied with the finite element method. The results show that the plateau stress, peak stress and specific energy absorption (SEA) of Al5052 honeycomb decrease gradually with increasing temperature, while the crush load efficiency (CLE) and deformation pattern are temperature insensitive. Then, based on the numerical results in this study and super folding element theory, the temperature dependent theoretical models without fitting parameters for the plateau stress and SEA of metallic honeycombs are developed, respectively. These theoretical models are successfully verified against numerical simulations and experiments. Based on these theoretical models, the effects of parent material properties on the plateau stress and SEA at different temperatures are discussed. The results in this study provide useful guidelines in optimizing the choice of parent materials to fabricate metallic honeycombs with better energy absorption efficiency at different temperatures.