Reusable 3D-Printed Thermoplastic Polyurethane Honeycombs for Mechanical Energy Absorption

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.

In this paper, a hybrid thin-walled tube with multiple cells and multiple materials is proposed to achieve lightweight, high energy absorption efficiency, and low cost of structures. Energy absorption characteristics and crushing deformation of the hybrid structures are investigated by experimental testing and numerical analysis. Meanwhile, theoretical prediction models of the mean crushing force for hybrid structures are developed and its accuracy was verified. It is found from the sensitivity analysis that the parameters of the multi-cell structure have significant effects on energy absorption. Furthermore, the multi-objective optimization including surrogate models is performed to obtain optimal crashworthiness of the multi-cell hybrid tube. The same optimal results were obtained using the full factor response mapping optimization algorithm and the non-dominated sorting genetic algorithm with elite strategy algorithm for multi-objective optimization solution. Compared with the original multi-cell hybrid tube and multi-cell pure aluminum (Al) tube, the optimized structure showed an increase of 0.25% and 25.31% in specific energy absorption, an increase of 16% and 77.34% in average crushing force, and an increase of 3.89% and 23.08% in energy absorption efficiency, respectively.

Three-dimensional (3D) parts are widely gaining popularity in industries like automotive, aerospace, medical healthcare, consumer goods, and electronics. The properties and performance of these parts vary depending on the parameters chosen at the design and manufacturing stages. This study experimentally evaluates the impact of topology on energy absorption and structural stability of eight strut-based lattice topologies fabricated using Fused Deposition Modeling (FDM) with Polylactic Acid (PLA). Quasi-static compression tests were conducted in accordance with ASTM D695. Specific Energy Absorption (SEA), crush force efficiency (CFE), and newly defined metrics—Peak-to-Plateau Load Ratio (PPLR) and Structural Efficiency (SE)—were used to determine collapse behavior and load stability. All lattices were manufactured within a narrow relative density range (0.29–0.30) to ensure topology-driven assessment. The Double Octagon lattice showed superior performance, achieving a maximum SEA of 6653.18 J kg⁻¹ , total absorbed energy of 57.55 J, and the highest structural efficiency among the investigated configurations. Substantial energy dissipation and trustworthy collapse mechanisms were shown by the Hex Truss and Kelvin cell; however, the Face Centered and Face Diagonal structures showed comparatively lower energy absorption. The proposed PPLR metric quantifies initial peak load severity relative to sustained collapse response, complementing conventional SEA and CFE measures. The findings highlight the critical role of topology optimization in balancing stiffness, weight, and energy absorption in guiding lightweight crashworthy lattice design.

Lightweight cellular materials are engineered to enhance performance attributes such as energy absorption, specific stiffness, negative Poisson's ratio, negative thermal expansion coefficient, etc. However, self‐sensing functionality of such architected materials is seldom explored. Herein, a combined experimental and numerical study on additive manufacturing (AM)‐enabled self‐sensing cellular composites processed via fused filament fabrication, utilizing in‐house engineered multiwall carbon nanotube (MWCNT)/polypropylene random copolymer (PPR) filament feedstocks, is reported. The tunable self‐sensing and enhanced mechanical performance of PPR/MWCNT lattices are experimentally demonstrated by varying their architectural parameters in addition to the MWCNT content. The lattices reveal strain and damage sensitivity gauge factors of 12 and 1.2, respectively, comparable to bulk materials’ commercial gauge factors. Furthermore, self‐sensing lattices exhibit 200%, 155%, 153%, and 137% increase in stiffness, energy absorption capacity (as high as 4.7 MJ m−3), specific energy absorption (20.5 J g−1), and energy absorption efficiency (90%), respectively, compared with their non‐reinforced counterparts. The tunable multifunctional performance of AM‐enabled cellular composites demonstrated here provides guidelines for the design and development of composite lattices with advantaged structural and functional properties for an array of applications such as patient‐specific biomedical devices capable of measuring comfort in prosthetics.

Energy absorption characteristics of bio-inspired hierarchical multi-cell bi-tubular tubes

Damage and energy absorption behavior of CFRP/aluminum hybrid open-section thin-walled columns subjected to quasi-static loading

The utilization of additive manufacturing in producing tubular honeycomb (THC) structures, leveraging capabilities of fused filament fabrication, enables the introduction of attributes, such as buckling initiators, to augment energy absorption characteristics. Increasing crush efficiency and/or energy absorption efficiency of THC structures bolsters payload and occupant protection in vehicular systems during impact scenarios such as collisions for ground vehicles or harsh landings for aircraft. In this investigation, THC structures composed of acrylonitrile butadiene styrene (ABS) plastic were additively manufactured so that buckling initiators (BIs) could be efficiently incorporated in the THC structure and readily positioned at the top, 3/4 height, or half height of the samples. Each configuration was subjected to quasi-static (0.03 mm/s) and constant (0.5 m/s) velocity testing employing an MTS machine, with three specimens manufactured for each test condition. Results demonstrated a notable 12.60% increase in energy absorption efficiency and a 15.75% increase in crush efficiency for specimens featuring BIs at the top of the sample as compared to those without BIs under quasi-static conditions. Furthermore, substantial improvements were also observed under constant velocity testing, indicating the efficacy of BIs at the top of the sample in promoting structural folding and progressive collapse, thereby increasing crush energy absorption and crush efficiency.

Purpose This study aims to enhance a decision-support system that offers optimum solutions to obtain the optimal topology using a sheet-based triply periodic minimal surface (TPMS) and carbon fiber-reinforced polymer (CFRP). Design/methodology/approach Within the scope of this study, the mechanical responses resulted by changing the orientation, type, size, relative density and graded relative density of the unit cells likewise the number of composite layers were examined. Wrapped around the sheet-based TPMSs, the CFRP allowed the lattices to absorb more energy during deformation, maintaining their shape integrity. An artificial neural network (ANN) was trained to reveal the relationships between the design parameters and mechanical properties. Findings According to SHAP values, the highest significance in the ANN model was determined as mass, graded relative density, cell size and number of composite layers. The significance of mass was greater than the sum of the importance of the other design parameters. An approximately linear relationship existed between the design parameters and peak crushing force, mean crushing force, energy absorption and plateau stresses, whereas specific energy absorption (SEA) and crushing load efficiency (CLE) had a complex relationship. Originality/value The non-dominated sorting genetic algorithm-II (NSGA-II) was used to find the optimum solution from the complex relationship between the design parameters and SEA and CLE. Design parameters for optimum crashworthiness were determined using NSGA-II, a heuristic optimization method using an ANN as the objective function.

Energy absorption of bio-inspired multi-layered graded foam-filled structures under axial crushing

Investigation on the microstructure and compressive behavior of open-cell copper- Al2O3 composite foams

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

The radiation absorption profiles on the surfaces of TiO2 films in a corrugated‐plate photocatalytic reactor were modeled based on first principles. A new term, the local‐area‐specific rate of energy absorption (LASREA), was adopted to describe the catalyst surface radiation in heterogeneous photoreactors. The LASREA and the energy absorption efficiency were both quite sensitive to the dimensions of the corrugated plates. Due to the multiple photon reflections between the opposing surfaces, corrugated plates possess a superior capability for recapturing longer wavelength photons that would otherwise be reflected out of some reactor designs. This results in higher energy absorption efficiency and more uniform LASREA on the catalyst films. Compared to a flat plate, corrugations are predicted to enhance the energy absorption efficiency by up to 50% for UV‐A fluorescent‐lamp‐powered systems and more than 100% for solar‐powered systems.

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.

Crashworthiness design draws considerable attention and interest in energy absorption systems. An optimal design of circular stepped tubes based on free inversion is presented in the current work to improve and enhance the crashworthiness characteristics under axial impact loading. Circular tubes have been known to be efficient energy absorbers per unit weight, and may be considered as the main part of energy absorbing devices even for frequently impact operation like landing gear or for sudden accidents like other vehicles. The precise choice of the circular tubes' material, shape, and mechanism may save a person life or save a valuable equipment from damage. Adaptive Multiple-Objective Optimization (AMO) can obtain more light and efficient section. An optimization of variable parameters, which represent the shape of a stepped tube under axial impact, is performed using the platform of ANSYS-DESIGN-EXPLORATION linked with LSDYNA code. The analysis leads to 16% reducing in mass with corresponding 31% improving in energy absorption.

High energy absorption efficiency and biodegradable polymer based microcellular materials via environmental-friendly CO2 foaming for disposable cushioning packaging