Quasi-static Axial Compression Research Articles

Breaking mechanical performance trade-off in 3D-printed complex lattice-inspired multi-cell tubes under axial compression

It is a long-standing challenge to balance the structural load capacity and toughness in the design of lightweight multi-cell tubes. To tackle this challenge, we provide two kinds of complex lattice-inspired composite multi-cell tubes. The composite multi-cell tubes consist of inner polylactic acid (PLA) complex lattice-inspired multi-cell tubes and outside aluminum tubes. The energy absorption capacity of these multi-cell tubes was evaluated under quasi-static axial compression. The effect of cross-sectional topology and thermal exposure were considered in the experiment. The results show that the integration of PLA tubes within aluminum tubes significantly enhances their energy absorption performance, effectively addressing the limitations posed by the low fracture strain of PLA. The synergistic effect between the aluminum and PLA tubes mitigates the fracture instability and distributes the load more evenly, resulting in improved specific energy absorption (SEA) and mean crushing force (MCF) up to 103.32% and 184.38%, respectively. In these composite tubes, a global self-similar layout can markedly enhance its energy absorption. However, their mechanical properties decrease significantly at 323K compared to room temperature. Overall, this research provides a novel approach to enhancing the mechanical performance of PLA tubes, paving the way for their application in engineering fields requiring lightweight and high-strength structures.

Study on the evolution rules of coal deformation and failure characteristics caused by multiple mining disturbances

During coal mining operations, the coal will be deformed and damaged due to multiple mining disturbances (MMD), often resulting in disasters, like rock burst. To understand the evolution rules of coal deformation under MMD and its final fracture characteristics after impact dynamic load loading, reduce the adverse effects of mining disturbances, and improve disaster prevention and control capabilities, quasi-static uniaxial cyclic loading-unloading (L-U) and dynamic axial compression tests were conducted on large-sized coal-like samples. During the tests, three-dimensional (3D) laser scanning and acoustic emission (AE) monitoring technology were utilized to accurately capture the full-field deformation and AE response data, facilitating a systematic analysis of deformation and fracture characteristics. The results show that: (1) Under the cyclic L-U effect induced by MMD, each loading cycle causes compression deformation with partial recovery during unloading, presenting an overall “wavy” variation trend. (2) The maximum load is the most critical factor affecting the damaged coal deformation, with smaller load resulting in less overall sample deformation. (3) After the impact dynamic loading, the damaged samples suffered large-scale impact splitting failure, with the compressive-shear layer failure mainly occurred inside the holes. (4) Lower loading during cyclic L-U process correlate with reduced damage degree, and smaller debris particles with a higher fractal dimension when impact failure occurs, indicating a more severe impact failure. (5) With multiple cycles of L-U, the cracks inside the sample gradually extend and expand from around the hole to the outside. The greater the load and the number of cycles, the more serious the crack damage will be. (6) In the practical mining process, it is crucial to reinforce roadway interiors while minimizing low-loading cyclic disturbances induced by MMD. The study has obtained the deformation evolution rules and failure characteristics of coal under MMD, providing a theoretical basis for the prevention and control of corresponding engineering disasters.

Crushing behavior of GFRP composite-reinforced PVC tubes: Experimental testing and numerical simulation

This paper introduces glass fiber reinforced polymer (GFRP)-reinforced Polyvinyl Chloride (PVC) tubes, both corrugated and non-corrugated, designed as energy absorber devices. The PVC tubes were externally and internally reinforced with GFRP composite oriented at ±45∘ and subjected to quasi-static axial compression tests. Results indicated that all reinforced tubes exhibited significantly higher load-bearing capacity, energy absorption capability, and crushing force efficiency compared to standard PVC tubes. Among the tested specimens, externally reinforced corrugated tubes demonstrated the highest specific energy absorption (SEA), surpassing other configurations by 17.5 kJ/kg when considering both pre- and post-crushing stages combined. However, these corrugated specimens showed instability during crushing, reflected in poor instantaneous crush force efficiency (iCFE) and the lowest iCFE among the composite tubes, with an average decrease of 43.59%.The corrugation notably increased the initial peak load, enhancing energy absorption in the pre-crushing stage without compromising the stability of crush force efficiency (CFE). Additionally, the combination of external and internal reinforcement significantly improved CFE and iCFE. Consequently, the PVC tubes combining corrugation with both external and internal reinforcement emerged as the best-performing configuration among all tested tubes.Furthermore, a 3D Finite Element (FE) model was developed using ABAQUS FE code with user-defined subroutines to simulate the crushing process. The constitutive models and numerical procedures employed are detailed. The FE model’s predictions showed a satisfactory correlation with experimental results, providing valuable insights into the crushing mechanics and offering a predictive tool for future design optimizations.

An experimental investigation into crashworthiness of filament wound intra-yarn hybrid glass/jute epoxy composites tubes under quasi-static axial and lateral compression

The increasing demand for sustainable materials in the automotive industry has driven the research towards exploration of natural fiber composites for crash structures. This study investigates the quasi-static axial and lateral crushing behavior of hybrid glass/jute fiber epoxy tubes. Intra-yarn hybrid mixing ratios of jute and glass fibers were tested to evaluate the feasibility of using natural fibers as eco-friendly alternatives to traditional synthetic composites. A total of five different configurations were fabricated using filament winding process. The experimental results were analyzed for collapsing behavior, failure modes, and energy absorption characteristics. The hybrid epoxy tubes revealed fiber-matrix fracturing, local buckling, and delamination as three primary failure modes under crushing tests. The hybrid configuration with 25 % jute fiber and 75 % glass fiber demonstrated optimal crashworthiness performance, achieving the highest specific energy absorption (SEA) values of 15.85 J/g under axial loading and 2.96 J/g under lateral loading. The configurations with higher jute content of 50 % and 75 %, showed decreasing SEA and crush force efficiency (CFE) values, with brittle fracturing and delamination as dominant failure modes, indicating a trade-off between weight and energy absorption efficiency. The neat glass fiber configuration maintained nearly consistent CFE values of 0.55 and 0.56, between axial and lateral loadings respectively, demonstrating isotropic behavior in energy absorption. Conversely, the neat jute fiber configuration improved SEA to 12.14 J/g under axial loading but exhibited significant limitations under lateral loading, with SEA decreasing to 0.69 J/g. Visual examination of crushed samples highlighted local buckling in GF configurations and brittle fracturing in hybrid and neat jute fiber configurations. The scanning electron microscope (SEM) analysis provided detailed insights into the microstructural characteristics and failure mechanisms, highlighting the inter-laminar debonding between the jute and glass fibers in hybrid configuration. By evaluating the combined effects of hybridization and loading conditions, the present study contributes to developing eco-friendly and efficient materials for automotive safety, aligning with industry sustainability goals.

Improving the crashworthiness of bi-tubular architectures with ABS cores under axial loading: Experimental and numerical investigation

In this study, quasi-static axial compression tests were conducted on mild steel bi-tubular architectures with rectangular nested tube (RNT) and square nested tube (SNT) geometries to evaluate their crushing and crashworthiness performance. A multi-criteria decision-making approach was employed to identify the optimal energy-absorbing architecture. The SNT structure, with the smallest gap size between the inner and outer tubes, exhibited the most desirable energy absorption characteristics among the considered cases. Acrylonitrile butadiene styrene (ABS) cores, with either rhombic or square cell configurations, were used to enhance the energy absorption performance of the SNT structure. A finite element model was created to evaluate the responses of the SNT structure filled with ABS cores. The validity of finite element simulations of the ABS cores and optimal architecture under axial compression were confirmed by comparing them with experimental results. The integration of the cores into the nested architecture enhanced crashworthiness performance and contributed to the control of the structure deformation. The SNT structure filled with rhombic ABS core exhibited superior crashworthiness performance compared to the counterpart filled with square core. The energy absorption of nested SNT structures filled with rhombic ABS core can be 116.93% greater than the corresponding non-filled structure. The crashworthiness indices of ABS-filled structures were highly sensitive to the number of cells and wall thickness of the core. A nested architecture with an ABS core could serve as a novel architecture for energy-absorbing devices.

Multi-objective optimization through desirability function analysis on the crashworthiness performance of thermoplastic/thermoset hybrid structures

This paper aims to optimize the crashworthiness capability of glass-reinforced epoxy composites (GFRE) over wrapped polyvinyl chloride (PVC) circular tubes with cutouts. The intended tubes were prepared by a wet wrapping method; then subjected to quasi-static axial compression. To compute crashworthiness indications, three design parameters, each at three levels, were used. The design parameters are the hole diameter (d), the hole's number (n), and the hole position (L). A few runs were accompanied by the L9 orthogonal array based on the Taguchi technique. With the lowest initial peak crash force (Fip) and the largest absorbed energy (U), the optimal parameters were found. Furthermore, the main effect, signal-to-noise ratio (S/N), as well as the analysis of variance (ANOVA), have been studied using the commercial software program MINITAB 18. Furthermore, to optimize the process parameters in terms of the crashworthiness indicators, desirability function analysis (DFA) was applied. Lastly, tests for confirmation were performed to verify the predicted values in light of the experimental results and compare them with the intact tubes. Regarding the single optimization, the optimum Fip tube is smaller than the intact PVC tube and intact hybrid tube, at 24.01 and 72.85 %, respectively. Nonetheless, the optimal U was 21.43 % lower than the intact hybrid tube and 152.75 % greater than the intact PVC tube. While, for Fip and U, the multi-objective optimization specimen achieves 5.13 and 70.02 % greater than the intact PVC tube. But it was 62.44 % and 47.14 % less than what the intact hybrid tube had accomplished.

Performance and failure modes of continuous fibre-reinforced energy absorption tubes by cylindrical layered 3D printing

ABSTRACT Precisely controlling the distribution of continuous fibres on a cylindrical surface is crucial for manufacturing high-performance continuous fibre-reinforced composite (CFRC) tubular structures. Existing manufacturing processes are complex, hindering the regulation of fibre orientation and content. Therefore, this study achieved unrestricted control of 3D-printed continuous fibres in terms of content and arbitrary orientation on a cylindrical surface using a cylindrical layered path planning strategy. The study investigated the impact of different fibre orientations and printing parameters on the compressive performance and energy absorption of 3D-printed CFRC tubes under quasi-static axial compression by analysing fibre distribution and failure modes. Compared to the flat layered printing strategy, the cylindrical layered printing strategy showed significant increases in compressive strength and energy absorption, by 44.3% and 85.2%, respectively. A cusp height analysis model demonstrated that the cylindrical layered printing strategy significantly enhances forming accuracy compared to the conventional flat layered method. The CFRC lightweight energy absorption tubes fabricated with this strategy demonstrated the viability of the manufacturing process. This new manufacturing technology has significant potential for producing high-performance and high-precision CFRC energy absorption tubes, applicable in aeronautics and astronautics.

Energy absorption characteristics of a bio-inspired prepreg carbon fiber crash box under quasi-static axial compression

Reducing vehicle weight is crucial for enhancing fuel efficiency and reducing emissions in transportation. Traditional composite materials offer improved energy absorption over metals yet are limited by brittleness. This study introduces an innovative approach, inspired by the mantis shrimp's natural defense mechanisms, to enhance the crashworthiness and energy absorption of composite structures, optimizing safety and performance. Utilizing a bio-inspired design, we developed corrugated Carbon Fiber Reinforced Polymer (CFRP) crash box structures, aiming to optimize their energy absorption capabilities and crash force efficiency (CFE) for potential applications in transportation safety. Through a series of quasi-static axial compression tests, the corrugated structures' performance was evaluated against traditional crash box designs. The experimental results demonstrate that the bio-inspired configurations improved crashworthiness characteristics. Strategic manipulation of layer numbers and corrugations led to superior CFE values, indicative of safer, more controlled collision behavior. The “7N-6L” configuration featuring seven corrugations with six layers of CFRP demonstrated the highest efficacy, achieving an optimal CFE of 1.08. This configuration demonstrated a Specific Energy Absorption (SEA) of 1.56 J/g and an Energy Absorption (Ea) of 42.56 J. Furthermore, compared to conventional steel crash boxes, the CFRP crash box with 7N-6L corrugated structure showcased competitive energy absorption capabilities with significantly reduced mass, absorbing 2850 J with a CFE of 0.91, nearly matching the ideal CFE and highlighting its superior lightweight performance. These results underline the potential of integrating bio-inspired designs to develop robust, lightweight structures for improved crashworthiness, paving the way for safer and more sustainable transportation solutions.

Novel interaction effects enhance specific energy absorption in foam-filled CFRP tapered tubes

This study unveils a novel interaction effect in the foam-filled CFRP tapered tubes that enhances their specific energy absorption (SEA), challenging the conventional understanding that foam fillers decrease the SEA of structures like foam-filled CFRP straight tubes and foam-filled metal tapered tubes. Quasi-static axial compression tests were conducted on foam-filled CFRP tubes with varying taper angles (0°, 5°, 10°, 15°) to confirm and quantify this newfound interaction effect. The energy absorption characteristics and interaction effect due to the foam filler in the foam-filled CFRP tapered tubes were thoroughly evaluated and compared to 3D-printed 316L stainless steel tubes and unfilled CFRP counterparts. Contrary to expectations, our results indicate that the foam-filled CFRP tubes consistently outperform both steel and unfilled CFRP tubes in energy absorption. Intriguingly, the CFRP foam-filled tapered tubes in this study demonstrated higher SEA compared to CFRP tubes without foam filler, underscoring the remarkable effectiveness of CFRP materials in foam-filled tapered tube applications. Our comprehensive interaction effect analysis highlights the substantial contribution of the unique synergy between the foam filler and the debris of the CFRP tapered tube to this increased SEA. Additionally, we propose a novel hybrid design that integrates straight and tapered CFRP tubes with foam fillers, leveraging the newfound interaction effect to further enhance the energy absorption of tapered tubes. This research not only emphasizes the advantages of foam fillers in enhancing CFRP tapered structures but also introduces innovative possibilities for energy absorption applications across various industries.

Crashworthiness analysis and optimization of a novel thin-walled multi-cell structure inspired by bamboo

The sophistication and regularity of natural materials continuously provide inspiration for mankind. Mimicking biological materials to devise advanced energy absorption structures remains grand challenges. Herein, we demonstrate a new type of thin-walled multi-cell structure, based on the shape and distribution characteristics of bamboo cross-sections. Numerical simulations of the proposed structure under quasi-static axial compression, lateral compression, and three-point bending are conducted through the finite element method. The crashworthiness of the new structure is compared with that of two other classic bamboo-inspired structures and an ordinary circular tube, and the results show that the present has superior specific energy absorption (SEA), compression efficiency, and deformation mode. Besides, our study also investigates the effects of the wall thickness of bamboo-inspired cell elements and the bio-inspired inner shell on the axial crashworthiness of the proposed structure. An optimal design of the bamboo-inspired structure was obtained by particle swarm optimization and the results reveal that, with the initial peak force (IPF)/SEA almost unchanged, the associated performance in SEA/IPF is significantly improved. Along with this guideline, it may provide a meaningful avenue towards the design of new bio-inspired energy absorption structures.

Geometric Accuracy and Energy Absorption Characteristics of 3D Printed Continuous Ramie Fiber Reinforced Thin-Walled Composite Structures

The application of continuous natural fibers as reinforcement in composite thin-walled structures offers a feasible approach to achieve light weight and high strength while remaining environmentally friendly. In addition, additive manufacturing technology provides a favorable process foundation for its realization. In this study, the printability and energy absorption properties of 3D printed continuous fiber reinforced thin-walled structures with different configurations were investigated. The results suggested that a low printing speed and a proper layer thickness would mitigate the printing defects within the structures. The printing geometry accuracy of the structures could be further improved by rounding the sharp corners with appropriate radii. This study successfully fabricated structures with various configurations characterized by high geometric accuracy through printing parameters optimization and path smoothing. Moreover, the compressive property and energy absorption characteristics of the structures under quasi-static axial compression were evaluated and compared. It was found that all studied thin-walled structures exhibited progressive folding deformation patterns during compression. In particular, energy absorption process was achieved through the combined damage modes of plastic deformation, fiber pullout and delamination. Furthermore, the comparison results showed that the hexagonal structure exhibited the best energy absorption performance. The study revealed the structure-mechanical property relationship of 3D printed continuous fiber reinforced composite thin-walled structures through the analysis of multiscale failure characteristics and load response, which is valuable for broadening their applications.

Failure modes and energy absorption mechanism of CFRP thin-walled square tubes filled with gradient foam aluminum under axial compression

Carbon Fiber Reinforced Plastic (CFRP) thin-walled square tube filled with gradient foam aluminum represents a novel component known for its exceptional energy absorption capabilities. This paper investigates the failure modes and energy absorption mechanisms of CFRP thin-walled square tubes filled with gradient foam aluminum using a combination of numerical simulations and quasi-static axial compression tests. The influences of some factors, including lay-up angles, lay-up sequences, and lay-up thicknesses have been analyzed. Additionally, the impact of the gradient foam aluminum filler on the crashworthiness characteristics has been scrutinized. The results reveal that the samples with lay-up angles below 45° showed a failure mode characterized by layer bundle buckling during axial compression. Conversely, the samples with lay-up angles exceeding 45° exhibited lateral shear failure during axial compression, with the latter demonstrating notably higher energy absorption efficiency. Increasing the proportion of circumferential angle and setting the circumferential angle on both the inner and outer sides of the axial lay-up, the energy-absorption capacity of the filled CFRP tubes under axial compression can be improved. This study demonstrates the potential of CFRP tubes filled with gradient foam aluminum to be used as energy absorbers.

Quasi-static compression tests of overwrapped composite pressure vessels under low velocity impact

Pressure vessels are being utilised in different applications that are indispensable including automobile, aerospace, underwater vehicles, oil and gas, chemical engineering among other applications. However, there is lack of knowledge on the influence of induced damage and the resulting performance of such vessels under quasi-static loading and axial compression. Specifically, the vessels studied in this study is made up of a high-density polyethylene liner and glass fibre overwraps. Therefore, this research investigated the load bearing capacities and the energy absorbed of the indented vessels in axial and hoop directions to determine the resistance of the vessels after such damaged using experiment, and damage characterisation microscopy, non-destructive testing and analysis.Quasi-static transverse and axial compression testing was performed on composite cylinders made of polyethylene liner and glass fibre overwraps. Both quasi-static and axial compression tests were performed with Universal testing Machines at crosshead speed of 500 mm/min 2.5 mm/min respectively. Microstructural damage characterisation was conducted using microscopy and Dolphicam2 ultrasonic non-destructive testing equipment.This study provides a new understanding on the performance of composite pressure vessel under damaged and undamaged conditions has established the reliability and residual strength capabilities of composites under the scenarios investigated. The results shows that the damage profile and the effect on compressive strength of the composite damaged and non-damaged cylinders was found to be relatively similar. However, when the cylinders are subjected to quasi-static compression, the polyethylene absorbs enough elastic strain energy to recover from the applied compressive load and recover without being plastically deformed. Additionally, the results demonstrate that the quasi-static compression have little or no influence on the axial strength of the cylinders. The damage characterisation on the cylinders revealed fibre break and delamination and local bucking and brooming failure at the bottom of the cylinders. This study has direct impact in composite overwrapped pressure vessels (COPVs) safety design tolerances, manufactururing strategy and operational failure conditions.

Crashworthiness of Hybrid Pipes with Triggering Mechanism Under Quasi-static Axial Compression

Crashworthiness of Hybrid Pipes with Triggering Mechanism Under Quasi-static Axial Compression

Hydrothermal aging effect on crushing characteristics of intraply hybrid composite pipes

In this study, the crushing properties of hybrid glass, basalt, and carbon fiber-reinforced composite pipes under a hydrothermal aging environment were investigated. Hybrid and non-hybrid composite pipes manufactured by filament winding technique were immersed in distilled water and seawater at 30 °C for four months. The water sorption parameters of the samples were calculated theoretically and weighed experimentally. Dry and aged pipes were subjected to quasi-static axial compression to examine aging effects on the crushing properties. The experimental weighing results showed that all composites exhibited a Fickian-like water absorption line. The non-hybrid basalt pipes were the most water-absorbing among all groups. In addition, the results proved that the hybridization effect in pipes is highly effective on water absorption parameters. In line with the results of non-hybrid pipes, hybrid pipes containing basalt fiber absorbed more water than other hybrid ones. Additionally, pipes aged in different environments showed that composite pipes absorbed more distilled water compared to seawater. Also, it was found that hydrothermal aging having adverse effects on the crushing characteristics of the pipes led to significant decreases. This can be explained by the degradation of the fiber–matrix interphase due to aging. However, maximum specific energy absorptions were achieved from non-hybrid carbon pipes regardless of environmental conditions. Also, the hybridization enhanced the crushing properties of the non-hybrid pipes that have lower characteristics. Additionally, it can be said that hybrid samples providing better stability in crushing showed better mean crushing load values since they mostly had a progressive crushing mode. The maximum mean crushing loads were obtained from the unconditioned hybrid GC samples as 36.2 kN which was 9.5 % and 34 % higher than unconditioned hybrid CB and BG samples. In conclusion, the study proved that the samples with low crushing properties can be improved by hybridization even if they are subjected to harsh environmental conditions.

Study on Quasi-Static Axial Compression Performance and Energy Absorption of Aluminum Foam-Filled Steel Tubes.

To study the axial compression performance of aluminum foam-filled steel tube and empty steel tube as objects, such tubes are studied in this paper, which explores the carrying capacity and deformation behavior of aluminum foam-filled steel tube with different lengths under a quasi-static axial load through experimental research. The carrying capacity, deformation behavior, stress distribution, and energy absorption characteristics of empty steel tubes and foam-filled steel tubes are compared through finite element numerical simulation. The results indicate that, compared with the empty steel tube, the aluminum foam-filled steel tube still presents a large residual carrying capacity after the axial force exceeds the ultimate load, and the whole compression process reflects steady-state compression. In addition, the axial and lateral deformation amplitudes of the foam-filled steel tube decrease significantly during the whole compression process. After filling the foam metal, the large stress area decreases and the energy absorption capacity improves.

Mechanical and energy absorption properties of 3D-printed honeycomb structures with Voronoi tessellations

3D printing technology is the new frontier in building construction. It is especially useful for making small structures within a short period. Full construction, including interior partitions and exterior façades, can be achieved with this technology. This paper proposes a parametric Voronoi tessellations model for quickly generating and fabricating 3D-printed hexagonal honeycomb partitions for interior design. Comprehensive experimental testing was conducted to characterize the mechanical properties and investigate the energy absorption characteristics of the proposed 3D-printed hexagonal honeycomb while comparing it to alternative hexagonal honeycomb structures. The tests included tensile testing (ASTM-D638) of the printed Polylactic Acid (PLA) material, especially with the almost total absence of conducted research that reported mechanical properties for 3D printed material with low infill percentages such as 10%. In addition, an in-plane quasi-static axial compression testing of the lightweight honeycomb structures was also conducted on the printed structure with the same low infill percentage. Compared to non-Voronoi honeycomb structures, the Voronoi honeycomb resulted in superior mechanical and energy absorption properties with energy absorption values ranging from 350 to 435 J and crash force efficiency being 1.42 to 1.65.

Influence of density gradient and hybrid effect on quasi-static axial crushing behavior of lattice cylindrical structures

Uniform/gradient lattice cylindrical structures (ULCS/GLCS) and hybrid uniform/gradient lattice cylindrical structures (HULCS/HGLCS) are innovatively designed and fabricated. The axial crushing behaviors of these four-type cylindrical structures are investigated by the quasi-static axial compression experiments and numerical simulations. The influence of the density gradient and the hybrid effect (metal skin+ABS core) on the deformation mode, loading capacity, and energy absorption of the lattice cylindrical structures are elaborated systematically. The results show that the gradient design realizes the function of regulation and controllability of the structural deformation. The softer layers (with smaller relative density) in GLCS begin to deform first and then gradually extend to the harder layers (with larger relative density). And it effectively reduces the initial peak compression force (PCF), and makes the load more stable on the premise of energy absorption. However, unstably catastrophic failures are observed before the final densification in both ULCS and GLCS during the compression due to the brittleness of the ABS material and the compression–expansion​ deformation of structure. For HULCS/HGLCS, it presents progressive crushing mode and overcome the unstably catastrophic failure due to the ductility and constraint of the metal skins. The effect of “1 ＋ 1 > 2” on energy absorption from hybrid effect is achieved in HULCS/HGLCS, in which the EA of HULCS and HGLCS increases by 74.62% and 100.78% comparing the sum of all components individually compressed. Moreover, the progressive peak with increasing trend of HGLCS demonstrated that the hybrid design enhances the advantages of gradient design in sandwich structures.

Study on quasi-static axial compression performances and energy absorption of four-star double arrow honeycomb

A four-star double arrow honeycomb (FS-DAH) is proposed. Firstly, representative cell of FS-DAH is chosen by adopting asymptotic homogenization method. Then, in-plane large deflection equations along X and Y compression directions are constructed by utilizing elliptic integral approach, elastic modulus, Poisson's ratio and platform stress of FS-DAH are derived.Subsequently, finite element model (FEM) of FS-DAH is constructed, and quasi-static axial compression simulation analysis is executed. To further verify the accuracy of theoretical predictions and FEM, samples with PLA material are manufactured by employing 3D printing technology, and quasi-static compression test is conducted. The results indicate that FS-DAH exhibit “zigzag” deformation mode along transverse direction and “wave” deformation mode along longitudinal direction under Y compression and “><” deformation mode appears under X compression, which are both consistent with simulation analysis. Moreover, there exist two platform regions and one platform zone along Y and X directions for stress–strain curves accordingly, the errors of simulation and theoretical results are within allowable range compared with test in terms of elastic modulus, platform stress and Poisson’s ratio. Eventually, FEMs with various concave angles and cell number are investigated, and its unit mass energy absorption decreases with the increment of concave angle and cell number.

Quasi-static compressive behaviors of large-size titanium lattice sandwich structure based on pulse hot-wire arc additive manufacturing

Large-size lattice sandwich structure (LSS) has broad application prospects in the industrial field because of its specific stiffness and high strength. Quasi-static compression behavior is one of the basic mechanical properties of LSS. In this paper, large size titanium pyramid lattice sandwich structures were fabricated by pulse hot-wire arc additive manufacturing (PHWAAM). The mechanical properties and failure modes of pyramid LSS were studied by quasi-static axial compression tests. Theoretical and experimental analyses showed that the compression strength of 4-cells LSS differs greatly from that of 5-cells LSS, and the specific strength and specific stiffness also differ significantly. 5-cells LSS has better compression behavior, strength is 608.23 MPa higher than the 4-cells LSS. The process of lattice damage during the experiment was observed, and the failure mode was analyzed by theoretical calculation together with metallography and fracture. The main failure mode is brittle fracture, but there is plastic deformation in some lattice cells. The compression properties of the two kinds of LSS are studied by finite element method (FEM) and compared with the theoretical and experimental results. The research findings presented in this study provide a concise and effective guidance for quasi-static compressive behaviors of large-size LSS. The proposed conclusion is of great significance to the explore of the mechanical properties of LSS manufactured by WAAM.